JP7107234B2 - Velocity measuring method and velocity measuring device - Google Patents

Description

The present invention relates to a speed measuring method and a speed measuring device.

In steel product manufacturing sites, it is necessary to measure the distance to an object to be measured with high precision and calculate its dimensions and shape for the purpose of quality control of products and automation of manufacturing processes. As a distance measuring device for measuring the distance to the object to be measured and measuring the shape of the object to be measured in such a bad environment, for example, as shown in Patent Document 1, an FSF laser (frequency shift feedback laser (Frequency-Shifted Feedback Laser) A distance measuring device using a light source is known.

Generally, in a distance measuring device using a laser beam whose frequency is modulated with respect to time, the frequency-modulated light emitted from a laser oscillator is split into a reference beam and a measurement beam, and the measurement The object to be measured is irradiated with light, and the reflected light that has returned after being reflected by the surface (measurement surface) of the object to be measured is made incident on the photodetector. On the other hand, the reference light is incident on the photodetector through a path having a predetermined optical path length. Therefore, the path from the light exiting the laser oscillator to the light detection section as reflected light through the reflection on the measurement surface of the object to be measured, and the light detection section after the light exiting the laser oscillator as the reference light. The optical path length is usually different from the path leading to . Therefore, the time required for the light to reach the photodetector after leaving the laser oscillator is also different between the reflected light and the reference light.

The frequency of the light emitted from the laser oscillator constantly changes with time at a predetermined frequency modulation speed based on a predetermined rule (triangular wave, comb wave, sine wave, etc.) grasped in advance by the operator. Therefore, the frequencies of the reflected light and the reference light that enter the photodetector are different. Therefore, in the photodetector, a beat signal having a frequency equal to the frequency difference between the reflected light and the reference light is detected due to interference between the reflected light and the reference light.

The frequency of the beat signal (beat frequency) is the time required for the measurement light to reach the photodetector as reflected light after leaving the laser oscillator, and the time required for the reference light to reach the photodetector after leaving the laser oscillator. It is equal to the amount of change in the oscillation frequency of the laser oscillator in the time difference from the required time. Therefore, in a distance measuring device using a laser beam whose frequency is modulated with respect to time (preferably, a laser beam whose frequency is linearly modulated), the beat frequency is converted into a difference in optical path length. , the distance to the object to be measured can be measured.

By knowing the distance to the object to be measured, it is also possible to know the shape of the object to be measured from the position information, speed information, etc. of the measurement surface. Therefore, the distance measuring device can also be used as a shape measuring device.

Here, for example, an example of using a distance measuring device at a manufacturing site of steel products will be described. When the steel sheet is conveyed in one direction along the length of the steel sheet, the measuring surface of the steel sheet moving at a predetermined speed (also referred to as sheet threading speed) is irradiated perpendicularly with the measuring light from the measuring head of the distance measuring device. The reflected light that has returned after being reflected by the measuring surface of the steel plate is received by the measuring head and sent to the photodetector.

The distance measuring device detects a beat signal with a frequency equal to the frequency difference between the reflected light and the reference light, and converts the beat frequency to the difference in optical path length to measure the moving steel plate. distance is measured in real time.

JP 2016-80409 A

Here, in a manufacturing site of steel products, various steel plates are conveyed, and the speed at that time may be different. High-precision speed measurement at the manufacturing site improves the dimensional quality of thickness and length, and high-precision tracking of cutting and welding positions speeds up lines and improves manufacturing efficiency. effective for For that purpose, it is necessary to measure the speed on-line with high accuracy. It is necessary to match the focal position (depth of focus).

However, since the surface position of the steel plate fluctuates due to vibration accompanying transportation and changes in its own size and shape, it is not easy to adjust the focus position, and as a result, it becomes difficult to measure the speed. It is also conceivable to press a contact-type rotating roller against the steel plate surface and measure the speed from the number of rotations of the roller. However, it is difficult to measure the velocity.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a speed measuring method and a speed measuring device capable of measuring the relative speed of an object to be measured.

The speed measuring method of the present invention is a speed measuring method for measuring the relative speed of an object to be measured, in which a laser oscillation step of oscillating a laser beam modulated at a predetermined frequency modulation speed with respect to time by a laser oscillator. a branching step of dividing the laser beam into a reference beam and a measurement beam; Using a first light receiving step of receiving the reflected light and a second measuring head, the object to be measured is irradiated with part of the measurement light, and the reflected light reflected by the surface of the object to be measured is received. detecting a first beat frequency based on the reflected light received by the first measuring head and the reference light; and detecting a first beat frequency based on the reflected light received by the second measuring head and the reference light. a frequency analysis step of detecting two beat frequencies; the first beat frequency detected when the object to be measured is relatively stationary at a reference position or moving at a reference speed; and the object to be measured calculates a first frequency difference, which is a frequency difference from the first beat frequency detected when the object is relatively moving at a speed other than the reference speed, and determines that the object to be measured is relatively stationary at the reference position Alternatively, the second beat frequency detected while moving at the reference speed and the second beat frequency detected while the object to be measured is relatively moving at a speed other than the reference speed a frequency difference calculating step of calculating a second frequency difference, which is a frequency difference between the two; In the plane formed by the direction and the optical axis of the first measuring head, a first optical axis angle formed by the direction perpendicular to the moving direction and the optical axis of the first measuring head, and the relative position of the object to be measured. a second optical axis angle formed by a direction perpendicular to the moving direction and the optical axis of the second measuring head, and the first frequency; Based on the difference and the second frequency difference, the relative velocity of the object to be measured with respect to the first measuring head and the second measuring head is measured.

A speed measuring device according to the present invention is a distance speed measuring device for measuring a relative speed of an object to be measured, wherein a laser oscillation unit for oscillating laser light modulated at a predetermined frequency modulation speed with respect to time; a splitter for dividing a laser beam into a reference beam and a measurement beam; a head, a second measuring head that irradiates the object to be measured with part of the measurement light and receives the reflected light reflected by the surface of the object to be measured, and the reflected light received by the first measurement head and the reference light to detect a first beat frequency; and a second frequency analysis unit to detect a second beat frequency based on the reflected light received by the second measuring head and the reference light. and the first beat frequency detected when the object to be measured is relatively stationary at a reference position or is moving at a reference speed, and the object to be measured is relatively at a speed other than the reference speed a first frequency difference calculator that calculates a first frequency difference that is a frequency difference from the first beat frequency that is detected while moving; , a frequency between the second beat frequency detected when the object is moving at the reference speed and the second beat frequency detected when the object to be measured is moving relatively at a speed other than the reference speed; A second frequency difference calculator for calculating a second frequency difference, which is a difference, and a speed calculator. In the plane formed by the direction and the optical axis of the first measuring head, a first optical axis angle formed by the direction perpendicular to the moving direction and the optical axis of the first measuring head, and the relative position of the object to be measured. a second optical axis angle formed by a direction perpendicular to the moving direction and the optical axis of the second measuring head, and the first frequency; Based on the difference and the second frequency difference, the relative velocity of the object to be measured with respect to the first and second measuring heads is measured.

According to the speed measuring method and the speed measuring device of the present invention, it is possible to easily measure the speed when the object to be measured moves by using the laser beam used when measuring the distance to the object to be measured. can. Further, according to a speed measuring method having a distance change amount calculation step and a speed measuring device having a distance change amount calculation unit, the distance to the object to be measured ( More directly, the difference in distance from the reference position to the object to be measured can be measured.

It is a schematic diagram showing the configuration of a first measurement head and a second measurement head. 1 is a block diagram showing the overall configuration of a speed measuring device of the present invention; FIG. It is the schematic which represented the chirp frequency comb output of FSF laser light typically. FIG. 10 is a schematic diagram for explaining the irradiation of the first measurement light and the second measurement light to a steel plate that is stationary at a predetermined position; 1 is a block diagram showing a circuit configuration of an arithmetic processing device according to a first embodiment; FIG. It is a block diagram which shows the circuit structure of the arithmetic processing unit which concerns on 2nd embodiment. FIG. 2 is a schematic diagram for explaining an embodiment; FIG. 8A is a graph showing the relationship between the distance change amount (movement distance) and the distance measurement value, and FIG. 8B is a graph showing the relationship between the distance change amount and the distance measurement error. FIG. 9A is a graph showing the relationship between the velocity and the velocity measurement value when the velocity of the object to be measured is changed at the reference position, and FIG. 9B is a graph showing the velocity measurement error obtained from FIG. 9A. , and FIG. 9C is a graph showing the relationship between the velocity and velocity measurement value error when the distance change amount is -50 mm and the velocity of the object to be measured is changed. FIG. 10A is a graph showing the relationship between speed and speed measurement error when the distance change amount is −100 mm and the speed of the object to be measured is changed. FIG. 10C is a graph showing the relationship between the speed and speed measurement error when the speed of the object to be measured is changed. 4 is a graph showing the relationship between , and speed measurement error. FIG. 10 is a schematic diagram showing the configuration of a speed measuring device provided with a first measuring head, a second measuring head, and a third measuring head according to a third embodiment; It is a schematic diagram for explaining a first projection angle, a second projection angle and a third projection angle. It is a block diagram which shows the circuit structure of the arithmetic processing unit which concerns on 3rd embodiment. It is a block diagram which shows the circuit structure of the arithmetic processing unit which concerns on 4th embodiment.

The present inventors measured the distance to the measuring surface S of the moving steel plate P using a distance measuring device using a general FSF (Frequency-Shifted Feedback) laser. It was confirmed that the obtained measurement distance changed. Therefore, the present inventors have made intensive studies on the cause of such changes in the measurement distance.

As a result, the present inventors found that the apparent shift in the measured distance when measuring the distance to the moving steel plate P using a laser oscillator is due to the Doppler shift of the laser beam. I found out what I thought was received. More specifically, as a cause of the shift in the measurement distance, it was presumed that the optical axis of the FSF laser was tilted with respect to the measurement surface S of the steel plate P, and that the Doppler shift affected the measurement distance.

Based on these assumptions, a method and an apparatus for measuring the velocity V of the steel plate P with high accuracy were investigated by eliminating the apparent shift of the measured value. At the same time, the measurement of the distance to the steel plate P was also examined.

(1) <First Embodiment>
A first embodiment of the present invention will be described in detail below with reference to the drawings.
(1-1) <Configuration of measuring head according to the present embodiment>
FIG. 1 shows a first measuring head 5a and a second measuring head 5b provided in a velocity measuring device according to this embodiment. The first measuring head 5a and the second measuring head 5b have the same configuration. The speed measuring device of the present invention includes a laser oscillator that oscillates FSF (Frequency-Shifted Feedback) laser light modulated at a known frequency modulation speed, and the FSF laser light (hereinafter also simply referred to as laser light) is The measurement surface (surface of the object to be measured) S of the moving steel plate P is irradiated with the first measurement light and the second measurement light from the first measurement head 5a and the second measurement head 5b, respectively.

Here, the inclination of the optical axis _ax1 of the first measurement light emitted from the first measuring head 5a (hereinafter referred to as the _first optical axis angle θ1) means the direction in which the steel plate P moves (moving direction X). and the optical axis _ax1 of the first measurement light, the angle formed between the direction perpendicular to the moving direction X and the optical axis _ax1 of the first measurement light. The inclination of the optical axis _ax2 of the second measurement light emitted from the second measuring head 5b (hereinafter referred to as the _second optical axis angle θ2) is the direction in which the steel plate P moves (moving direction X). It is the angle formed between the direction perpendicular to the movement direction X and the optical axis _ax2 of the second measurement light on the plane formed by the optical axis _ax2 of the second measurement light. The _first optical axis angle θ1 and the _second optical axis angle θ2 are different.

(1-2) <About the speed measuring device according to the first embodiment>
The speed measuring device in the first embodiment measures only the speed of the steel plate P in the movement direction X without measuring the distance to the steel plate P. As shown in FIG. 2, the speed measuring device 1 of this embodiment includes a laser oscillator 2 that oscillates FSF laser light, splitters 3a, 3b, and 3c, circulators (directional couplers) 4a and 4b, and a first measuring head. 5a, a second measuring head 5b, couplers (optical fiber couplers) 6a and 6b, a first photodetector 7a, a second photodetector 7b, and an arithmetic processing unit 11. FIG.

The laser oscillator 2 is a laser oscillator that oscillates FSF laser light. Here, FSF laser light is laser light oscillated by feedback of frequency-shifted light using a resonator (not shown) equipped with an element (frequency shift element) that changes the frequency of light. means

FIG. 3 is a diagram schematically showing the output of FSF laser light. As shown in FIG. 3, the FSF laser light is amplified and attenuated according to the gain curve (frequency-amplitude curve) of the resonator while the light wave in the resonator undergoes a frequency shift for each round, and finally Disappear. In the oscillation output of FSF laser light, a plurality of such instantaneous frequency components exist in a comb shape at regular frequency intervals.

In FIG. 3 , _τRT represents the resonator round trip time, and ν _FS represents the frequency shift amount per round trip. 1/ _τRT indicates the longitudinal mode frequency interval (chirp frequency comb interval) of the resonator, and _rs indicates the amount of change per unit time of the instantaneous frequency of the FSF laser light, that is, the frequency modulation speed.

As shown in FIG. 2, laser light (FSF laser light) output from a laser oscillator 2 is incident on a splitter 3a via an optical fiber. The splitter 3a splits the laser light incident from the laser oscillator 2 into measurement light and reference light. Moreover, the measurement light branched by the branching device 3a is incident on the branching device 3b via an optical fiber. This splitter 3b splits the measurement light into the first measurement light and the second measurement light. Note that the first measurement light and the second measurement light are also simply referred to as measurement light.

The first measurement light branched by the splitter 3b is guided to the first measurement head 5a via the first optical fiber optical path 8a. The first optical fiber optical path 8a has a circulator 4a between the first measuring light exiting the splitter 3b and the first measuring head 5a. The circulator 4a emits the first measurement light from the splitter 3b to the first measurement head 5a, and emits the first reflected light incident from the first measurement head 5a to the coupler 6a.

The first measuring head 5a is internally provided with an end portion 9a of the first optical fiber optical path 8a and a condenser lens 9b. The first measurement head 5a emits the first measurement light transmitted from the laser oscillator 2 via the first optical fiber optical path 8a from the end portion 9a of the first optical fiber optical path 8a, and collects the light through the condensing lens 9b. After condensing, the measurement surface S of the steel plate P is irradiated. The first measuring head 5a moves the measuring surface S of the steel plate P moving at a predetermined speed V in the movement direction X (one direction along the surface direction of the flat measuring surface S of the steel plate P) by a transport roller (not shown). Alternatively, the measurement surface S of the stationary steel plate P is irradiated with the first measurement light.

The first reflected light obtained by reflecting the first measurement light on the measurement surface S of the steel plate P is collected by the condenser lens 9b and then received by the end portion 9a of the first optical fiber optical path 8a. , enter the coupler 6a via the first optical fiber optical path 8a. Specifically, the first reflected light received by the first measuring head 5a is guided to the circulator 4a through the same optical fiber as that through which the first measuring light passed, and from the circulator 4a to the coupler 6a through the optical fiber. be guided.

On the other hand, the reference light branched by the first splitter 3a enters the splitter 3c via an optical fiber. This splitter 3c splits the reference light into a first reference light and a second reference light. Note that the first reference light and the second reference light are also simply referred to as reference light. The first reference light branched by the splitter 3c is guided to the first photodetector 7a through the third optical fiber optical path 8c. Specifically, the first reference light emitted from the splitter 3c is guided to the coupler 6a through an optical fiber having a predetermined optical path length. The coupler 6a causes the first reference light and the first reflected light to enter the first photodetector 7a through optical fibers.

The first photodetector 7a receives the first reflected light and the first reference light. The first reflected light and the first reference light that enter the first photodetector 7a at the same time are the optical path lengths of the respective laser beams that travel from the laser oscillator 2 to the first photodetector 7a. , a beat signal is generated by optical interference between the first reflected light and the first reference light. The first photodetector 7 a detects this beat signal and sends it to the processor 11 .

On the other hand, the second measurement light branched by the splitter 3b is guided to the second measurement head 5b via the second optical fiber optical path 8b. The second optical fiber path 8b has a circulator 4b between the second measuring light exiting the splitter 3b and reaching the second measuring head 5b. The circulator 4b emits the second measurement light from the splitter 3b to the second measurement head 5b, and emits the second reflected light incident from the second measurement head 5b to the coupler 6b.

The second measuring head 5b has the same configuration as the first measuring head 5a, and transmits the second measuring light transmitted from the laser oscillator 2 through the second optical fiber optical path 8b to After being emitted from the end portion 9a of the optical path 8b and condensed by the condensing lens 9b, the measurement surface S of the steel plate P is irradiated. The second measurement head 5b also irradiates the second measurement light toward the measurement surface S of the steel plate P that is moving in the moving direction X at a predetermined speed V or the measurement surface S of the steel plate P that is stationary.

The second reflected light obtained by reflecting the second measurement light on the measurement surface S of the steel plate P is collected by the condenser lens 9b and then received by the end portion 9a of the second optical fiber optical path 8b. , enter the coupler 6b via the second optical fiber optical path 8b. Specifically, the second reflected light received by the second measuring head 5b is guided to the circulator 4b through the same optical fiber as that through which the second measuring light passed, and from the circulator 4b through the optical fiber to the coupler 6b. be guided. Note that the above-described first reflected light and second reflected light are also simply referred to as reflected light.

On the other hand, the second reference light branched by the splitter 3c is guided to the second photodetector 7b through the fourth optical fiber optical path 8d. Specifically, the second reference light emitted from the splitter 3c is guided to the coupler 6b through an optical fiber having a predetermined optical path length. The coupler 6b allows the second reference light and the second reflected light to enter the second photodetector 7b through optical fibers.

The second photodetector 7b receives the second reflected light and the second reference light. The second reflected light and the second reference light, which enter the second photodetector 7b at the same time, are the optical path lengths of the laser beams that travel from the laser oscillator 2 to the second photodetector 7b. , a beat signal is generated by optical interference between the second reflected light and the second reference light. The second photodetector 7 b detects this beat signal and sends it to the processor 11 .

The arithmetic processing unit 11 determines the frequency (first beat frequency) of the beat signal generated by optical interference between the first reflected light and the first reference light in the group of light detected by the first photodetector 7a. within the detection frequency range. In addition, in order to suppress the influence of the temperature change of the optical fiber, instead of the beat frequency generated by the optical interference between the first reflected light and the first reference light, the first beat frequency, for example, the first measurement head A frequency corresponding to the distance D1 from 5a to the measurement surface S of the steel plate P can be used. When calculating this frequency, the beat frequency generated by optical interference between the reflected light from the first measuring head 5a and the reference light is subtracted from the beat frequency generated by the interference between the first reflected light and the reference light. can be found at

Further, the arithmetic processing unit 11 detects the frequency of the beat signal (second beat frequency) generated by optical interference between the second reflected light and the second reference light in the group of light detected by the second photodetector 7b. , within a predetermined detection frequency range. Also in this case, for example, a frequency corresponding to the distance D2 from the second measuring head 5b to the measuring surface S of the steel plate P can be used. When calculating this frequency, the beat frequency generated by the optical interference between the reflected light and the second reference light at the second measuring head 5b is calculated from the beat frequency generated by the optical interference between the second reflected light and the second reference light. It can be obtained by subtracting the beat frequency.

When the first measuring head 5a and the second measuring head 5b are perpendicular to the movement direction X of the steel plate P, or when the steel plate P is stationary, the first beat frequency or the second beat frequency is set to the optical path The distance to the steel plate P can be obtained by converting to length.

In addition to this, when the first measuring head 5a and the second measuring head 5b are inclined, the arithmetic processing unit 11 performs arithmetic processing according to the velocity measuring method described later to obtain the first beat frequency and the The second beat frequency can be used to measure the velocity V as the steel plate P is moving.

(1-3) <Regarding the speed measurement method of the present invention>
Next, the speed measuring method according to the present invention will be described with reference to FIGS. 1 and 4. FIG. In this speed measuring method, the speed V of the moving steel plate P can be measured using a laser beam as in the conventional method. In the velocity measurement method, two of the first measurement head 5a and the second measurement head 5b are used, and the measurement surface S of the steel plate P is irradiated with the first measurement light from the first measurement head 5a, and The measurement surface S of the steel plate P is irradiated with the second measurement light.

At this time, the first measuring head _5a and the second measuring head 5b are arranged at different positions with respect to the steel plate P, and the inclination ( The first optical axis angle θ ₁ ) and the inclination of the optical axis _ax2 of the second measurement light emitted from the second measuring head 5b (the second optical axis angle θ ₂ ) are each set at a predetermined angle. . The _first optical axis angle θ1 and the _second optical axis angle θ2 may be the same angle or different angles.

The angle in this case is perpendicular to the moving direction X on the plane formed by the moving direction X of the steel plate P and the optical axis a _x1 of the first measuring head 5a (the optical axis a _x2 of the second measuring head 5b). It is the angle between the direction and the optical axis a _x1 of the first measuring head 5a (the optical axis a _x2 of the second measuring head 5b), and is the angle of the directional component over which the Doppler effect extends.

1 and 4, for the sake of simplicity, as an example according to the present embodiment, the optical axes a _x1 and a _x2 of the first measuring head 5a and the second measuring head 5b are both aligned with the moving direction X. The case is shown in the plane formed by the vertical direction Z (hereinafter also simply referred to as the direction Z), and the following description will be based on that example.

Here, FIG. 1 shows a steel plate P moving at a speed V along a moving direction X at a predetermined position at a predetermined distance from the first measuring head 5a and the second measuring head 5b. On the other hand, in FIG. 4, in which parts corresponding to those in FIG. 1 shows a steel plate P which has been cut.

That is, since the steel plate P is stationary at the reference position, the Doppler effect does not occur, and even if the distance to the steel plate P is measured using the speed measuring device 1, the above-described apparent shift in the measured distance occurs. true distance can be measured.

Here, in the plane formed by the moving direction X of the steel plate P and the optical axes a _x1 and a _x2 of the first measuring head 5a and the second measuring head 5b, in a direction Z perpendicular to the moving direction X, a predetermined position (Fig. The difference in the distance between the steel plate P at 1) and the steel plate P at the reference position (FIG. 4) is hereinafter referred to as distance variation d. In FIG. 4, as an example, compared to the steel plate P in the moving state, along the direction Z perpendicular to the moving direction X, the distance change amount d shows a steel plate P moved by .

Here, a first beat frequency (first reference frequency) obtained from the first reflected light reflected from the measurement surface S of the steel plate P (FIG. 4) in a stationary state at the reference position and the first reference light, The difference in frequency (hereinafter referred to as the first frequency If the first frequency difference Δf ₁ is affected by the distance variation d and the Doppler shift, the first frequency difference Δf ₁ can be expressed by the following equation (1).

Δf ₁ =k(d/cos θ ₁ )−(2V sin θ ₁ )/λ (1)

θ ₁ indicates the above-mentioned first optical axis angle, and λ indicates the wavelength of the laser. For example, k is a constant that indicates how much the frequency of the laser light changes when the distance of the steel plate P with respect to the first measuring head 5a and the second measuring head 5b is changed.

In the above formula (1), the first term indicates the amount of change in the frequency of the laser light (first reflected light) due to the change in the distance from the first measuring head 5a to the steel plate P. On the other hand, the second term of the above formula (1) is a term indicating the frequency change amount of the laser light (first reflected light) due to the influence of the Doppler shift caused by the movement of the steel plate P along the moving direction X. is.

Further, a second beat frequency (second reference frequency) obtained from the second reflected light reflected from the measurement surface S of the steel plate P (FIG. 4) in a stationary state at the reference position and the second reference light, and a predetermined The difference in frequency between the second reflected light reflected from the measurement surface S of the steel plate P (FIG. 1) moving in position and the second beat frequency obtained from the second reference light (hereinafter referred to as the second frequency difference ) is denoted by Δf2, the _second frequency difference Δf2 is also affected by the distance change amount d and the Doppler shift, so it can be expressed by the following equation ( ₂ ).

Δf ₂ =k(d/cos θ ₂ )+(2V sin θ ₂ )/λ (2)

Since the first measuring head 5a and the second measuring head 5b have the same configuration, the constant k is the same as that of the first measuring head 5a.

When the speed V when the steel plate P moves in the X direction is calculated from the above formulas (1) and (2), it can be expressed by the following formula (3).

V=(λ/2)・(−Δf ₁ cos θ ₁ +Δf ₂ cos θ ₂ )/(sin θ ₁ cos θ ₁ +sin θ ₂ cos θ ₂ ) (3)

Here, the wavelength λ of the laser light can be obtained by measuring in advance using a spectroscope or the like. For the constant k in the above formulas (1) and (2), for example, a distance change amount d is provided, the steel plate P is stopped at different positions, and the first reflected light from the steel plate P at each position ( or the frequency of the second reflected light) is measured and calculated from the frequency change amount of the first reflected light (or the second reflected light) at this time and the distance change amount d.

Specifically, for example, the first measurement head 5a irradiates the steel plate P, which is kept still at the reference position, with the first measurement light, and the frequency of the obtained first reflected light is measured. Further, the steel plate P, which is stationary at a predetermined position shifted by the distance change amount d from the reference position, is irradiated with the first measurement light from, for example, the first measurement head 5a, and the frequency of the obtained first reflected light is measured. do. By calculating the frequency difference Δf ₁₁ of each first reflected light when the steel plate P is at each position, the constant k can be calculated based on the formula k=Δf ₁₁ /d. . Such a constant k can be used when obtaining the distance change amount d described in the second embodiment.

As described above, since the first measuring head 5a and the second measuring head 5b have the same configuration, using either the first measuring head 5a or the second measuring head 5b, It suffices to calculate the frequency difference _Δf11 of the reflected light.

In addition, it is possible to obtain k by calculating k = 2r _S /c without actually performing a test using the steel plate P that is stationary at the reference position or the steel plate P that is shifted by the distance change amount d. be. _rs is the amount of change per unit time of the instantaneous frequency of the laser beam, that is, the frequency modulation speed, and c is the speed of light in air.

In the above equation (3), the first optical axis angle θ ₁ changes the velocity V when the steel plate P moves in the X direction at the same position, and the first reflected light reflected from the steel plate P and the first reference light The first beat frequency obtained from the light is measured at each speed, and each can be calculated from the amount of change in the first beat frequency at this time and the difference between the speeds V. FIG. For the second optical axis angle θ ₂ , similarly to the first optical axis angle θ ₁ , the velocity V when the steel plate P moves in the X direction is changed at the same position, and the second reflection reflected from the steel plate P The second beat frequency obtained from the light and the second reference light is measured at each speed, and each can be calculated from the amount of change in the second beat frequency at this time and the difference in speed V. .

Specifically, the first optical axis angle θ1 can be calculated using the second term of the above equation ( ₁ ), and the second optical axis angle θ1 can be calculated using the second term of the above equation (2). ₂ can be calculated. For example, the steel plate P is moved at a plurality of velocities V ₁ and V ₂ along the movement direction X at the same position, and the difference between the first beat frequencies detected at these velocities V ₁ and V ₂ is called the frequency difference. Δf is calculated as ₂₁ . Also, the speed difference between the speeds V ₁ and V ₂ is calculated as the speed V _D1 for calibration.

As a result, the first optical axis angle θ1 of the _first measurement light is obtained by using the wavelength λ of the laser light, the velocity _VD1 for calibration, and the frequency difference _Δf21 , and the second (ie, Δf ₂₁ =2V _D1 ·Sin θ ₁ /λ).

Similarly, for the second optical axis angle θ2 of the _second measurement light, the wavelength λ of the laser light, the velocity VD1 for calibration, and the frequency difference _Δf22 are used to obtain the above equation ₍ 2). It can be calculated from the second term (ie, Δf ₂₂ =2V _D1 ·Sin θ ₂ /λ).

From the above, the wavelength λ of the laser light, the _first optical axis angle θ1, and the _second optical axis angle θ2 in the above equation (3) can be obtained in advance. Therefore, by measuring the first frequency difference Δf ₁ and the second frequency difference Δf ₂ , the speed V at which the steel plate P moves can be calculated from the above equation (3).

When constructing the velocity measuring device 1, if the _first optical axis angle θ1 and the _second optical axis angle θ2 are known accurately, or if the first optical axis angle When θ1 and the _second optical axis angle θ2 _are known, the velocity V can be calculated directly from the above equation (3) using the _first optical axis angle θ1 and the _second optical axis angle θ2. can be calculated.

In the present embodiment, the _first frequency difference Δf1 is calculated by combining the first beat frequency detected when the steel plate P is stationary relative to the first measuring head 5a at the reference position and the steel plate P at the predetermined position. The first beat frequency detected when P is moving relative to the first measuring head 5a is used to calculate the frequency difference as the _first frequency difference Δf1, but the present invention is limited to this. do not have. For example, a first beat frequency detected when the steel plate P is moving at a reference speed relative to the first measuring head 5a at a reference position, and a first beat frequency detected at a predetermined position when the steel plate P is moving at a speed other than the reference speed relative to the first measuring head 5a. The frequency difference may be calculated as the _first frequency difference Δf1 using the first beat frequency detected during relative movement.

Similarly, when calculating the _second frequency difference Δf2, it is not necessary to use the second beat frequency detected when the steel plate P is stationary relative to the second measuring head 5b at the reference position. For example, the second beat frequency detected when the steel plate P is moving at a reference speed relative to the second measuring head 5b at the reference position and the second beat frequency detected at a predetermined position when the steel plate P is moving at a speed other than the reference speed relative to the second measuring head 5b The frequency difference may be calculated as the _second frequency difference Δf2 by using the second beat frequency detected during relative movement.

In this embodiment, the first frequency difference Δf ₁ and the second frequency difference Δf ₂ are the first beat frequency and the second beat frequency detected when the steel plate P is relatively stationary at the reference position. A case of calculating using frequencies will be described below.

(1-4) <Regarding the processing unit>
Next, the arithmetic processing unit 11 (FIG. 2) for executing the speed measuring method described above will be described below. This arithmetic processing unit 11 can measure the speed V when the steel plate P moves based on the above equation (3) without obtaining the distance. FIG. 5 is a block diagram showing the circuit configuration of the arithmetic processing unit 11. As shown in FIG. As shown in FIG. 5, the arithmetic processing unit 11 includes a first frequency analysis unit 17a, a second frequency analysis unit 17b, a distance calculation unit 18, a calculation unit 13, and a wavelength acquisition unit 16. In addition, in the arithmetic processing unit 11, a frequency analysis unit is configured by the first frequency analysis unit 17a and the second frequency analysis unit 17b.

The first frequency analysis unit 17a receives a beat signal generated by optical interference between the first reflected light and the first reference light from the first light detection unit 7a, and converts the frequency of the beat signal (first beat frequency) into Detection is performed within a predetermined detection frequency range, and the detection result is sent to the distance calculation section 18, the first reference frequency acquisition section 18a, the first frequency difference calculation section 19a, and the first optical axis angle acquisition section 20a.

Further, the second frequency analysis unit 17b receives a beat signal generated by optical interference between the second reflected light and the second reference light from the second light detection unit 7b, and determines the frequency of the beat signal (second beat frequency). is detected within a predetermined detection frequency range, and the detection result is sent to the distance calculation section 18, the second reference frequency acquisition section 18b, the second frequency difference calculation section 19b, and the second optical axis angle acquisition section 20b.

The distance calculator 18 calculates the distance of the steel plate P to the measurement surface S by converting the first beat frequency or the second beat frequency into a difference in optical path length. When the distance calculator 18 measures the distance from the first beat frequency or the second beat frequency, if the steel plate P is moving, the measured distance will apparently shift due to the Doppler effect as described above. Therefore, the distance to the measurement surface S of the steel plate P which is stationary at a certain position is measured, and that position is used as the reference position.

The calculation unit 13 includes a first reference frequency acquisition unit 18a, a second reference frequency acquisition unit 18b, a first frequency difference calculation unit 19a, a second frequency difference calculation unit 19b, a first optical axis angle acquisition unit 20a, and a second optical axis angle acquisition unit 20a. An angle acquisition unit 20b and a speed calculation unit 24 are provided. In the calculation unit 13, the first reference frequency acquisition unit 18a and the second reference frequency acquisition unit 18b constitute a reference frequency acquisition unit, and the first frequency difference calculation unit 19a and the second frequency difference calculation unit 19b It constitutes a difference calculation unit. The first optical axis angle acquisition section 20a and the second optical axis angle acquisition section 20b constitute an optical axis angle acquisition section.

The first reference frequency acquisition unit 18a acquires the first reference frequency used when obtaining the first frequency difference Δf ₁ used in the above equation (3). The first reference frequency acquisition unit 18a stores the first beat frequency in the stationary state and the reference position received from the first frequency analysis unit 17a, that is, the first reference frequency. The first reference frequency acquisition unit 18a sends the first reference frequency to the first frequency difference calculation unit 19a.

The first frequency difference calculator 19a calculates the _first frequency difference Δf1 used in the above equation (3) and, if necessary, the first frequency difference used when obtaining the _first optical axis angle θ1. It is something to do. The first frequency difference calculation unit 19a is connected to the first light detection unit 7a via the first frequency analysis unit 17a. A signal indicative of one beat frequency is received. Also, the first frequency difference calculator 19a is connected to the first reference frequency acquisition unit 18a and receives a signal indicating the first reference frequency.

As a result, the first frequency difference calculator 19a calculates the difference between the first beat frequency detected from the steel plate P in the moving state and the first reference frequency detected from the steel plate P stationary at the reference position as the first frequency. The difference Δf is calculated as ₁ . The first frequency difference calculator 19a sends information indicating the _first frequency difference Δf1, which is the calculation result, to the speed calculator 24 .

The second reference frequency acquisition unit 18b acquires the second reference frequency used when obtaining the second frequency difference Δf ₂ used in the above equation (3). The second reference frequency acquisition unit 18b stores the second beat frequency in the stationary state and the reference position received from the second frequency analysis unit 17b, that is, the second reference frequency. The second reference frequency acquisition unit 18b sends the second reference frequency to the second frequency difference calculation unit 19b.

The second frequency difference calculator 19b calculates the _second frequency difference Δf2 used in the above equation (3) and, if necessary, the second frequency difference used when obtaining the _second optical axis angle θ2. It is something to do. The second frequency difference calculation unit 19b is connected to the second light detection unit 7b via the second frequency analysis unit 17b. A signal indicative of a 2-beat frequency is received. The second frequency difference calculator 19b is also connected to the second reference frequency acquirer 18b and receives a signal indicating the second reference frequency.

As a result, the second frequency difference calculator 19b calculates the difference between the second beat frequency detected from the steel plate P in the moving state and the second reference frequency detected from the steel plate P stationary at the reference position as the second frequency. The difference Δf is calculated as ₂ . The second frequency difference calculator 19b sends information indicating the _second frequency difference Δf2, which is the calculation result, to the speed calculator 24 .

The first optical axis angle acquisition unit 20a acquires the _first optical axis angle θ1 used in the above equation (3). The first optical axis angle acquisition unit 20a may calculate the _first optical axis angle θ1 by arithmetic processing, or measure the _first optical axis angle θ1 by a measuring means to acquire an actual measurement value. Alternatively, the _first optical axis angle θ1 may simply be stored in advance. The first optical axis angle acquisition unit 20a sends information indicating the _first optical axis angle θ1 to the speed calculation unit 24 .

Here, for example, when calculating the first optical axis angle θ ₁ by conducting an actual test, the steel plate P is moved at the same position along the movement direction X at a plurality of speeds V ₁ and V ₂ , and these The first beat frequencies detected at the velocities V ₁ and V ₂ are sent from the first frequency analysis section 17a to the first frequency difference calculation section 19a. The first frequency difference calculator 19a calculates the frequency difference between the first beat frequencies as a frequency difference Δf ₂₁ and sends it to the first optical axis angle acquirer 20a. The first optical axis angle acquisition unit 20a acquires the frequency difference Δf ₂₁ , the calibration velocity V _D1 indicating the velocity difference between the velocities V ₁ and V ₂ , and the wavelength λ. ) (that is, Δf ₂₁ =2V _D1 ·Sin θ ₁ /λ), the first optical axis angle θ ₁ is calculated.

The second optical axis angle acquisition unit 20b acquires the _second optical axis angle θ2 used in the above equation (3). The second optical axis angle acquisition unit 20b may calculate the _second optical axis angle θ2 by arithmetic processing, or measure the _second optical axis angle θ2 by the measurement means to acquire the measured value. Alternatively, the _second optical axis angle θ2 may simply be stored in advance. The second optical axis angle acquisition unit 20b sends information indicating the _second optical axis angle θ2 to the speed calculation unit 24 .

Here, for example, when calculating the _second optical axis angle θ2 by conducting _an actual test, the steel plate P is moved in the moving direction X at a plurality of velocities V ₁ and V ₂ , and the second beat frequencies detected at these velocities V ₁ and V ₂ are sent from the second frequency analysis unit 17b to the second frequency difference calculation unit 19b. do. The second frequency difference calculator 19b calculates the difference between the frequencies of the second beat frequencies as a frequency difference Δf ₂₂ , which is used by the second optical axis angle acquirer 20b. The second optical axis angle acquisition unit 20b acquires the frequency difference Δf ₂₂ , the calibration velocity V _D1 indicating the velocity difference between the velocities V ₁ and V ₂ , and the wavelength λ. ) (that is, Δf ₂₂ =2V _D1 ·Sin θ ₂ /λ), the second optical axis angle θ ₂ is calculated.

The wavelength acquisition unit 16 is, for example, a spectroscope or the like, and acquires the wavelength λ by measuring the wavelength λ of the laser light oscillated by the laser oscillator 2 . The wavelength acquisition unit 16 sends information indicating the wavelength λ to the speed calculation unit 24 .

Further, the velocity calculator 24 uses the acquired first frequency difference Δf ₁ , second frequency difference Δf ₂ , first optical axis angle θ ₁ , second optical axis angle θ ₂ , and wavelength λ of the laser beam. , the velocity V is calculated by arithmetic processing based on the above equation (3). Thus, the speed calculator 24 can measure the speed V of the steel plate P. FIG. At this time, as is clear from the above equation (3), the velocity calculator 24 can calculate the velocity V without using distance values such as the distance change amount d.

(1-5) <Action and effect>
In the above configuration, the velocity measuring device 1 according to the present embodiment oscillates laser light whose frequency is modulated with respect to time (laser oscillation step), and divides the laser light into reference light and measurement light (branching step). ). Using the first measuring head 5a and the second measuring head 5b, the measuring surface S of the steel plate P is irradiated with laser light corresponding to the measuring light from different positions, and the reflected light is sent to the first measuring head 5a and the second measuring head 5b. Light is received using each of them (first light receiving step, second light receiving step).

The velocity measuring device 1 measures and detects a first beat frequency using a beat signal obtained by causing interference between the first reflected light received by the first measuring head 5a and the first reference light. Further, the velocity measuring device 1 measures and detects the second beat frequency using the beat signal obtained by causing the second reflected light received by the second measuring head 5b to interfere with the second reference light (frequency analysis step).

Then, the speed measuring device 1 acquires the first beat frequency and the second beat frequency detected when the steel plate P is stationary at the reference position as the first reference frequency and the second reference frequency, respectively.

In the speed measuring device 1, a first beat frequency which is a difference between a first beat frequency detected when the steel plate P is moving at a predetermined position and a first reference frequency when the steel plate P is stationary at a reference position is detected. Calculate the frequency difference _Δf1 . In the speed measuring device 1, the difference between the second beat frequency detected when the steel plate P is moving at a predetermined position and the second reference frequency when the steel plate P is stationary at the reference position is A _second frequency difference Δf2 is calculated (frequency difference calculation step).

As a result, the speed measuring device 1 obtains information on the wavelength λ of the laser light, the first optical axis angle θ1 of the _first measurement light, and the _second optical axis angle θ2 of the second measurement light. , the calculated first frequency difference Δf ₁ and first frequency difference Δf ₂ can be used to calculate the speed V of the steel plate P from the above equation (3) (speed calculation step).

As described above, the speed measuring device 1 can measure the speed V of the steel plate P using a laser beam without measuring the distance value that is generally required for speed measurement.

Further, in the speed measuring device 1, for example, the above-described frequency difference calculation step is performed prior to the first measurement step and the second detection step, and the first reflected light detected when the steel plate P is stationary at the reference position and the reference frequency information of each frequency of the second reflected light is preferably stored in advance. As a result, when the speed measuring device 1 detects each frequency of the first reflected light and the second reflected light when the steel plate P is moving at a predetermined position, the already stored reference frequency information (reference position ), the first frequency difference Δf1 and the _first frequency difference Δf2 can be immediately calculated using the information on each frequency of the first reflected light and the _second reflected light when the steel plate P is stationary. Therefore, the speed V can be measured in real time while the steel plate P is being moved.

(2) <Second embodiment>
A second embodiment of the present invention will now be described in detail with reference to the drawings. In the following description, the same reference numerals are given to the same configurations as in the first embodiment, and overlapping descriptions will be omitted.

(2-1) <Configuration of measuring head according to the present embodiment>
The second embodiment also has a first measuring head 5a and a second measuring head 5b as shown in FIG. The first measurement head 5a and the second measurement head 5b have the same configuration as the first embodiment described above, and move using FSF laser light (laser light) as the first measurement light and the second measurement light. The measurement surface (surface of the object to be measured) S of the steel plate P to be measured is irradiated. Since the description of the first measuring head 5a and the second measuring head 5b overlaps with that of the above-described first embodiment, the description thereof is omitted here.

(2-2) <About the speed measuring device according to the second embodiment>
FIG. 2 shows the overall configuration of a speed measuring device 31 in the second embodiment. In addition to the speed of the steel plate P in the movement direction X, the speed measuring device 31 in the second embodiment also measures the difference in the distance from the reference position to the steel plate P (distance change amount d) in a series of processes at the same time. It is different from the above-described first embodiment in that it can be measured in a specific manner. A speed measuring device 31 in this embodiment differs from that in the above-described first embodiment in the configuration of an arithmetic processing device 32, and other points are configured in the same manner as in the first embodiment. Therefore, the following description focuses on the arithmetic processing unit 32, which is different from the first embodiment.

In this case, the first photodetector 7a receives the first reflected light and the first reference light, detects a beat signal generated by optical interference between the first reflected light and the first reference light, and processes the beat signal. Send to device 32 .

The second photodetector 7b receives the second reflected light and the second reference light, detects a beat signal generated by optical interference between the second reflected light and the second reference light, and sends it to the arithmetic processing unit 32. Send out.

The arithmetic processing unit 32 determines the frequency of the beat signal (first beat frequency) generated by optical interference between the first reflected light and the first reference light in the group of light detected by the first photodetector 7a. within the detection frequency range. In order to suppress the influence of the temperature change of the optical fiber, instead of the frequency of the beat signal generated by the optical interference between the first reflected light and the first reference light, the first beat frequency may be, for example, A frequency corresponding to the distance D1 from the measuring head 5a to the measuring surface S of the steel plate P can be used. When calculating this frequency, the beat frequency generated by the optical interference between the reflected light from the first measuring head 5a and the first reference light is calculated from the beat frequency generated by the interference between the first reflected light and the first reference light. can be obtained by subtracting

Further, the processing unit 32 detects the frequency of the beat signal (second beat frequency) generated by optical interference between the second reflected light and the second reference light in the group of light detected by the second photodetector 7b. , within a predetermined detection frequency range. Also in this case, for example, a frequency corresponding to the distance D2 from the second measuring head 5b to the measuring surface S of the steel plate P can be used. When calculating this frequency, the beat frequency generated by the optical interference between the reflected light from the second measuring head 5b and the second reference light is calculated from the beat frequency generated by the interference between the second reflected light and the second reference light. can be obtained by subtracting

When the first measuring head 5a and the second measuring head 5b are perpendicular to the movement direction X of the steel plate P, or when the steel plate P is stationary, the first beat frequency or the second beat frequency is set to the optical path The distance to the steel plate P can be obtained by converting to length.

In addition to this, when the first measuring head 5a or the second measuring head 5b is inclined, the arithmetic processing unit 32 performs arithmetic processing according to the distance speed measuring method described later to obtain the first beat frequency and the second beat frequency, the distance to the steel plate P and the speed V at which the steel plate P is moving can be measured.

(2-3) <Regarding the speed measurement method in the second embodiment>
Next, a speed measuring method according to the second embodiment will be described with reference to FIGS. 1 and 4. FIG. In the speed measuring method of the second embodiment, as in the first embodiment, the speed V of the steel plate P can be measured using a laser beam, and the distance to the steel plate P moving at that time can also be measured. They can be measured simultaneously. In the velocity measurement method, two of the first measurement head 5a and the second measurement head 5b are used, and the measurement surface S of the steel plate P is irradiated with the first measurement light from the first measurement head 5a, and The measurement surface S of the steel plate P is irradiated with the second measurement light.

At this time, the first measuring head _5a and the second measuring head 5b are arranged at different positions with respect to the steel plate P, and the inclination ( The first optical axis angle θ ₁ ) and the inclination of the optical axis _ax2 of the second measurement light emitted from the second measuring head 5b (the second optical axis angle θ ₂ ) are each set at a predetermined angle. . The _first optical axis angle θ1 and the _second optical axis angle θ2 may be the same angle or different angles.

The angle in this case is perpendicular to the moving direction X on the plane formed by the moving direction X of the steel plate P and the optical axis a _x1 of the first measuring head 5a (the optical axis a _x2 of the second measuring head 5b). It is the angle between the direction and the optical axis a _x1 of the first measuring head 5a (the optical axis a _x2 of the second measuring head 5b), and is the angle of the directional component over which the Doppler effect extends.

1 and 4, for the sake of simplicity, as an example according to the present embodiment, the optical axes a _x1 and a _x2 of the first measuring head 5a and the second measuring head 5b are both aligned with the moving direction X. The case is shown in the plane formed by the vertical direction Z (simply referred to as the direction Z), and the following description will be based on that example.

Here, FIG. 1 shows a steel plate P moving at a speed V along a moving direction X at a predetermined position at a predetermined distance from the first measuring head 5a and the second measuring head 5b. On the other hand, FIG. 4, in which parts corresponding to those in FIG. A steel plate P resting at a reference position different from the position is indicated by a dotted line.

That is, since the steel plate P is stationary at the reference position, the Doppler effect does not occur, and even if the distance to the steel plate P is measured using the velocity measuring device 31, the above-described apparent shift in the measured distance occurs. true distance can be measured.

Here, in the plane formed by the moving direction X of the steel plate P and the optical axes a _x1 and a _x2 of the first measuring head 5a and the second measuring head 5b, in a direction Z perpendicular to the moving direction X, a predetermined position (Fig. The difference in distance between the steel plate P at 1) and the steel plate P at the reference position (FIG. 4) is referred to as a distance variation d. In FIG. 4, as an example, compared to the steel plate P in the moving state, along the direction Z perpendicular to the moving direction X, the distance change amount d shows a steel plate P moved by .

Here, a first beat frequency (first reference frequency) obtained from the first reflected light reflected from the measurement surface S of the steel plate P (FIG. 4) in a stationary state at the reference position and the first reference light, A frequency difference (first frequency difference) between the first reflected light reflected from the measurement surface S of the steel plate P (FIG. 1) moving at a predetermined position and the first beat frequency obtained from the first reference light. is Δf ₁ , the first frequency difference Δf ₁ is affected by the distance change amount d and the Doppler shift. be able to.

Δf ₁ =k(d/cos θ ₁ )−(2V sin θ ₁ )/λ (1)

θ ₁ indicates the above-mentioned first optical axis angle, and λ indicates the wavelength of the laser. For example, k is a constant that indicates how much the frequency of the laser light changes when the distance of the steel plate P with respect to the first measuring head 5a and the second measuring head 5b is changed.

In the above formula (1), the first term indicates the amount of change in the frequency of the laser light (first reflected light) due to the change in the distance from the first measuring head 5a to the steel plate P. On the other hand, the second term of the above formula (1) is a term indicating the frequency change amount of the laser light (first reflected light) due to the influence of the Doppler shift caused by the movement of the steel plate P along the moving direction X. is.

Further, a second beat frequency (second reference frequency) obtained from the second reflected light reflected from the measurement surface S of the steel plate P (FIG. 4) in a stationary state at the reference position and the second reference light, and a predetermined The frequency difference (second frequency difference) between the second reflected light reflected from the measurement surface S of the steel plate P (FIG. 1) moving at the position and the second beat frequency obtained from the second reference light is , Δf2, the _second frequency difference _Δf2 is also affected by the distance variation d and the Doppler shift. can be done.

Δf ₂ =k(d/cos θ ₂ )+(2V sin θ ₂ )/λ (2)

Since the first measuring head 5a and the second measuring head 5b have the same configuration, the constant k is the same as that of the first measuring head 5a.

When the speed V when the steel plate P moves in the X direction and the distance change amount d of the steel plate P are calculated from the above formulas (1) and (2), the following formulas (3) and (4).

V=(λ/2)・(−Δf ₁ cos θ ₁ +Δf ₂ cos θ ₂ )/(sin θ ₁ cos θ ₁ +sin θ ₂ cos θ ₂ ) (3)
d=(cos θ ₁ cos θ ₂ )/k·(Δf ₁ sin θ ₂ +Δf ₂ sin θ ₁ )/(sin θ ₁ cos θ ₁ +sin θ ₂ cos θ ₂ ) (4)

Here, the wavelength λ of the laser light can be obtained by measuring in advance using a spectroscope or the like. Also, for the constant k, for example, the distance change amount d is provided, the steel plate P is stopped at different positions, and the frequency of the first reflected light (or the second reflected light) from the steel plate P at each position is changed to It can be calculated from the frequency change amount of the first reflected light (or the second reflected light) at this time and the distance change amount d.

Specifically, for example, the first measurement head 5a irradiates the steel plate P, which is kept still at the reference position, with the first measurement light, and the frequency of the obtained first reflected light is measured. Further, the steel plate P, which is stationary at a predetermined position shifted by the distance change amount d from the reference position, is irradiated with the first measurement light from, for example, the first measurement head 5a, and the frequency of the obtained first reflected light is measured. do. By calculating the frequency difference Δf ₁₁ of each first reflected light when the steel plate P is at each position, the constant k can be calculated based on the formula k=Δf ₁₁ /d. .

As described above, since the first measuring head 5a and the second measuring head 5b have the same configuration, using either the first measuring head 5a or the second measuring head 5b, It suffices to calculate the frequency difference _Δf11 of the reflected light.

In addition, it is also possible to obtain k by calculating k = 2r _s /c without performing a test using the steel plate P actually stopped at the reference position or the steel plate P shifted by the distance change amount d. be. Note that _rs indicates the amount of change in the instantaneous frequency of the laser light per unit time, that is, the frequency modulation speed, and c indicates the speed of light in air.

In the above equations (3) and (4), the first optical axis angle θ ₁ changes the speed V when the steel plate P moves in the X direction at the same position, and the first reflection reflected from the steel plate P The first beat frequency obtained from the light and the first reference light is measured at each speed, and each can be calculated from the amount of change in the first beat frequency at this time and the difference in speed V. . For the second optical axis angle θ ₂ , similarly to the first optical axis angle θ ₁ , the velocity V when the steel plate P moves in the X direction is changed at the same position, and the second reflection reflected from the steel plate P The second beat frequency obtained from the light and the second reference light is measured at each speed, and the difference between the second beat frequency change and the speed V can be calculated.

Specifically, the first optical axis angle θ1 can be calculated using the second term of the above equation ( ₁ ), and the second optical axis angle θ1 can be calculated using the second term of the above equation (2). ₂ can be calculated. For example, the steel plate P is moved at a plurality of velocities V ₁ and V ₂ along the movement direction X at the same position, and the difference between the first beat frequencies detected at these velocities V ₁ and V ₂ is called the frequency difference. Δf is calculated as ₂₁ . Also, the speed difference between the speeds V ₁ and V ₂ is calculated as the speed V _D1 for calibration.

As a result, the first optical axis angle θ1 of the _first measurement light is obtained by using the wavelength λ of the laser light, the velocity _VD1 for calibration, and the frequency difference _Δf21 , and the second (ie, Δf ₂₁ =2V _D1 ·Sin θ ₁ /λ).

Similarly, for the second optical axis angle θ2 of the _second measurement light, the wavelength λ of the laser light, the velocity VD1 for calibration, and the frequency difference _Δf22 are used to obtain the above equation ₍ 2). It can be calculated from the second term (ie, Δf ₂₂ =2V _D1 ·Sin θ ₂ /λ).

From the above, the wavelength λ of the laser light, the _first optical axis angle θ1, and the _second optical axis angle θ2 in the above equation (3) can be obtained in advance. Therefore, by measuring the first frequency difference Δf ₁ and the second frequency difference Δf ₂ , the speed V when the steel plate P moves in the X direction can be calculated from the above equation (3).

Similarly, for the above equation ( ₄ ), _{k =2r s /} Since the constant k) calculated from c can be obtained in advance, by measuring the first frequency difference Δf ₁ and the second frequency difference Δf ₂ , from the above equation (4) , the amount of change in the distance d between the steel plates P can be calculated.

When constructing the velocity measuring device 31, if the _first optical axis angle θ1 and the _second optical axis angle θ2 are known accurately, or if the first optical axis angle When θ ₁ and the second optical axis angle θ ₂ are known, using the first optical axis angle θ ₁ and the second optical axis angle θ ₂ directly, the above equations (3) and (4) , the velocity V and the amount of change in distance d can be calculated.

Also in the second embodiment, as in the first embodiment described above, the calculation of the first frequency difference Δf ₁ and the second frequency difference Δf ₂ is performed when the steel plate P is relatively positioned at the reference position. It is not necessary to use the first beat frequency and the second beat frequency detected when the steel plate P is stationary. The frequencies may be used to calculate a first frequency difference Δf ₁ and a second frequency difference Δf ₂ respectively. Here, for the _first frequency difference Δf1 and the _second frequency difference Δf2, the first beat frequency and the second beat frequency detected when the steel plate P is relatively stationary at the reference position are used. A case of calculating using the following will be described.

(2-4) <Regarding the processing unit>
Next, the processing unit 32 (FIG. 2) for executing the speed measurement method described above will be described below. This arithmetic processing unit 32 can measure the speed V when the steel plate P moves based on the laser beam, and based on the above equations (3) and (4), the distance change of the steel plate P from the reference position Quantity d can be measured simultaneously in a series of processes. FIG. 6 is a block diagram showing the circuit configuration of the arithmetic processing unit 32. As shown in FIG. As shown in FIG. 6, the arithmetic processing unit 32 includes a first frequency analysis unit 17a, a second frequency analysis unit 17b, a distance calculation unit 18, a calculation unit 13, a constant acquisition unit 14, and a wavelength acquisition unit 16. . In addition, in the arithmetic processing unit 32, a frequency analysis unit is configured by the first frequency analysis unit 17a and the second frequency analysis unit 17b.

The first frequency analysis unit 17a receives a beat signal generated by optical interference between the first reflected light and the first reference light from the first light detection unit 7a, and converts the frequency of the beat signal (first beat frequency) into Detection is performed within a predetermined detection frequency range, and the detection result is sent to the distance calculation section 18, the first reference frequency acquisition section 18a, the first frequency difference calculation section 19a, and the first optical axis angle acquisition section 20a.

Further, the second frequency analysis unit 17b receives a beat signal generated by optical interference between the second reflected light and the second reference light from the second light detection unit 7b, and determines the frequency of the beat signal (second beat frequency). is detected within a predetermined detection frequency range, and the detection result is sent to the distance calculation section 18, the second reference frequency acquisition section 18b, the second frequency difference calculation section 19b, and the second optical axis angle acquisition section 20b.

The distance calculator 18 calculates the distance of the steel plate P to the measurement surface S by converting the first beat frequency or the second beat frequency into a difference in optical path length. When the distance calculator 18 measures the distance from the first beat frequency or the second beat frequency, if the steel plate P is moving, the measured distance will apparently shift due to the Doppler effect as described above. Therefore, the distance to the measurement surface S of the steel plate P which is stationary at a certain position is measured, and that position is used as the reference position.

The calculation unit 13 includes a first reference frequency acquisition unit 18a, a second reference frequency acquisition unit 18b, a first frequency difference calculation unit 19a, a second frequency difference calculation unit 19b, a first optical axis angle acquisition unit 20a, and a second optical axis angle acquisition unit 20a. An angle acquisition unit 20b and a distance/velocity calculation unit 21 are provided. In the calculation unit 13, the first reference frequency acquisition unit 18a and the second reference frequency acquisition unit 18b constitute a reference frequency acquisition unit, and the first frequency difference calculation unit 19a and the second frequency difference calculation unit 19b It constitutes a difference calculation unit. The first optical axis angle acquisition section 20a and the second optical axis angle acquisition section 20b constitute an optical axis angle acquisition section.

The first reference frequency acquisition unit 18a acquires the first reference frequency used when obtaining the first frequency difference Δf ₁ used in the above equations (3) and (4). The first reference frequency acquisition unit 18a stores the first beat frequency in the stationary state and the reference position received from the first frequency analysis unit 17a, that is, the first reference frequency. The first reference frequency acquisition unit 18a sends the first reference frequency to the first frequency difference calculation unit 19a.

The first frequency difference calculator 19a calculates the _first optical axis angle θ1 and the constant k as needed in addition to the _first frequency difference Δf1 used in the above equations (3) and (4). to calculate the first frequency difference used for . The first frequency difference calculation unit 19a is connected to the first light detection unit 7a via the first frequency analysis unit 17a. A signal indicative of one beat frequency is received. Also, the first frequency difference calculator 19a is connected to the first reference frequency acquisition unit 18a and receives a signal indicating the first reference frequency.

As a result, the first frequency difference calculator 19a calculates the difference between the first beat frequency detected from the steel plate P in the moving state and the first reference frequency detected from the steel plate P stationary at the reference position as the first frequency. The difference Δf is calculated as ₁ . The first frequency difference calculator 19a sends information indicating the _first frequency difference Δf1, which is the calculation result, to the distance/velocity calculator 21 .

The second reference frequency acquisition unit 18b acquires the second reference frequency used when obtaining the second frequency difference Δf ₂ used in the above equations (3) and (4). The second reference frequency acquisition unit 18b stores the second beat frequency in the stationary state and the reference position received from the second frequency analysis unit 17b, that is, the second reference frequency. The second reference frequency acquisition unit 18b sends the second reference frequency to the second frequency difference calculation unit 19b.

The second frequency difference calculator 19b calculates the _second optical axis angle θ2 and the constant k as needed in addition to the _second frequency difference Δf2 used in the above equations (3) and (4). to calculate the second frequency difference used for The second frequency difference calculation unit 19b is connected to the second light detection unit 7b via the second frequency analysis unit 17b. A signal indicative of a 2-beat frequency is received. The second frequency difference calculator 19b is also connected to the second reference frequency acquirer 18b and receives a signal indicating the second reference frequency.

As a result, the second frequency difference calculator 19b calculates the difference between the second beat frequency detected from the steel plate P in the moving state and the second reference frequency detected from the steel plate P stationary at the reference position as the second frequency. The difference Δf is calculated as ₂ . The second frequency difference calculator 19b sends information indicating the _second frequency difference Δf2, which is the calculation result, to the distance/velocity calculator 21 .

The first optical axis angle acquisition unit 20a acquires the _first optical axis angle θ1 used in the above equations (3) and (4). The first optical axis angle acquisition unit 20a may calculate the _first optical axis angle θ1 by arithmetic processing, or measure the _first optical axis angle θ1 by a measuring means to acquire an actual measurement value. Alternatively, the _first optical axis angle θ1 may simply be stored in advance. The first optical axis angle acquisition section 20 a sends information indicating the first optical axis angle θ ₁ to the distance/speed calculation section 21 .

Here, for example, when calculating the first optical axis angle θ ₁ by conducting an actual test, the steel plate P is moved at the same position along the movement direction X at a plurality of speeds V ₁ and V ₂ , and these The first beat frequencies detected at the velocities V ₁ and V ₂ are sent from the first frequency analysis section 17a to the first frequency difference calculation section 19a. The first frequency difference calculator 19a calculates the difference between the first beat frequencies as a frequency difference Δf ₂₁ and sends it to the first optical axis angle acquirer 20a. The first optical axis angle acquisition unit 20a acquires the frequency difference Δf ₂₁ , the calibration velocity V _D1 indicating the velocity difference between the velocities V ₁ and V ₂ , and the wavelength λ. ) (that is, Δf ₂₁ =2V _D1 ·Sin θ ₁ /λ), the first optical axis angle θ ₁ is calculated.

The second optical axis angle acquisition unit 20b acquires the _second optical axis angle θ2 used in the above formulas (3) and (4). The second optical axis angle acquisition unit 20b may calculate the _second optical axis angle θ2 by arithmetic processing, or measure the _second optical axis angle θ2 by the measurement means to acquire the measured value. Alternatively, the _second optical axis angle θ2 may simply be stored in advance. The second optical axis angle acquisition section 20b sends information indicating the _second optical axis angle θ2 to the distance/velocity calculation section 21 .

Here, for example, when calculating the _second optical axis angle θ2 by conducting _an actual test, the steel plate P is moved in the moving direction X at a plurality of velocities V ₁ and V ₂ , and the second beat frequencies detected at these velocities V ₁ and V ₂ are sent from the second frequency analysis unit 17b to the second frequency difference calculation unit 19b. Send out. The second frequency difference calculator 19b calculates the difference between the frequencies of the second beat frequencies as a frequency difference Δf ₂₂ , which is used by the second optical axis angle acquirer 20b. The second optical axis angle acquisition unit 20b acquires the frequency difference Δf ₂₂ , the calibration velocity V _D1 indicating the velocity difference between the velocities V ₁ and V ₂ , and the wavelength λ. ) (that is, Δf ₂₂ =2V _D1 ·Sin θ ₂ /λ), the second optical axis angle θ ₂ is calculated.

The constant acquisition unit 14 acquires the constant k used in the above equation (4). The constant acquisition unit 14 may calculate the constant k by performing an actual test, or simply store the constant k in advance. The constant acquisition unit 14 sends information indicating the constant k to the distance/speed calculation unit 21 .

When calculating the constant k by conducting an actual test, for example, the position of the steel plate P is changed by the distance change amount d, and the frequency difference Δf ₁₁ of the first reflected light detected at each position is calculated as the first It is calculated by the frequency difference calculator 19a. The constant acquisition unit 14 acquires the frequency difference Δf ₁₁ of the first reflected light and the distance change amount d of the steel plate P when the position is changed, and based on the equation k=Δf ₁₁ /d , the constant k is calculated.

The wavelength acquisition unit 16 is, for example, a spectroscope or the like, and acquires the wavelength λ by measuring the wavelength λ of the laser light oscillated by the laser oscillator 2 . The wavelength acquisition unit 16 sends information indicating the wavelength λ to the distance/velocity calculation unit 21 .

The distance/velocity calculator 21 calculates the thus obtained first frequency difference Δf ₁ , second frequency difference Δf ₂ , first optical axis angle θ ₁ , second optical axis angle θ ₂ , constant k, Using the wavelength λ, the speed V and the distance change amount d when the steel plate P moves are calculated based on the above equations (3) and (4). Here, the distance speed calculation unit 21 includes a distance change amount calculation unit 23 that measures the distance change amount d, and a speed calculation unit 24 that measures the speed V of the steel plate P.

Using the acquired first frequency difference Δf ₁ , second frequency difference Δf ₂ , first optical axis angle θ ₁ , second optical axis angle θ ₂ , and constant k, the distance change amount calculator 23 calculates the above Arithmetic processing is performed based on the equation (4) to calculate the distance change amount d. In this manner, the distance change amount calculator 23 can measure the distance change amount d of the steel plate P. FIG.

Since this distance change amount d indicates a relative position with respect to the reference position, when obtaining the distance from the speed measuring device 31, it is possible to use the value of the distance to the reference position that has been measured in advance. , can be calculated.

Further, the velocity calculator 24 uses the acquired first frequency difference Δf ₁ , second frequency difference Δf ₂ , first optical axis angle θ ₁ , second optical axis angle θ ₂ , and wavelength λ of the laser beam. , the velocity V is calculated by arithmetic processing based on the above equation (3). Thus, the speed calculator 24 can measure the speed V of the steel plate P. FIG.

(2-5) <Action and effect>
In the above configuration, the velocity measuring device 31 according to the present embodiment also has a laser oscillation step, a branching step, a first light receiving step, a second light receiving step, a frequency analysis step, a frequency difference step, and a frequency difference step as in the first embodiment. Calculation was performed by executing the calculation step and obtaining information on the wavelength λ of the laser light, the first optical axis angle θ ₁ of the first measurement light, and the second optical axis angle θ ₂ of the second measurement light. Using the first frequency difference Δf ₁ and the first frequency difference Δf ₂ , the speed V of the steel plate P can be calculated from the above equation (3) (speed calculation step).

This velocity measuring device 31 does not simply calculate the velocity V from the second term of the above equation (1), but uses both the first measurement light and the second measurement light to determine the amount of change in the distance of the steel plate P. Since the above formula (3) is obtained by taking d into consideration, the speed V can be calculated accurately.

Further, in the speed measuring device 31, for example, the above-described frequency difference calculation step is performed prior to the first light receiving step and the second light receiving step, and the reference frequency detected when the steel plate P is stationary at the reference position are stored in advance as the first reference frequency and the second reference frequency. As a result, when the speed measuring device 31 detects each frequency of the first reflected light and the second reflected light while the steel plate P is moving at a predetermined position, the speed measuring device 31 detects the first reference frequency and the first reference frequency already stored. Using _two reference frequencies, the first frequency difference Δf1 and the _first frequency difference Δf2 can be calculated immediately. Therefore, the speed V can be measured in real time while the steel plate P is being moved.

Furthermore, in the speed measuring device 31 of the second embodiment, by acquiring the constant k that indicates the relationship between the change in the distance to the steel plate P and the change in the frequency of the laser beam, the first frequency difference Δf ₁ and the first Based on the two-frequency difference Δf ₂ , the first optical axis angle θ ₁ , the second optical axis angle θ ₂ , and the constant k, from the above equation (4), the distance change amount d of the steel plate P is also can be calculated (distance change amount calculation step). Further, by measuring the distance from the speed measuring device 31 to the reference position in advance, not only the distance change amount d but also the distance from the speed measuring device 31 to the steel plate P can be calculated. More specifically, the distance/speed calculation unit 21 receives the distance to the reference position (reference distance) measured by the distance calculation unit 18, adds or subtracts the distance change amount d from the reference distance, By correcting the distance to the reference position with the distance change amount d, the distances D1 and D2 from the speed measuring device 31 to the steel plate P can be calculated.

When measuring the distance change amount d, a constant k obtained by calculation from k=2r _s /c using the frequency modulation speed r _s may be stored in advance and used. Also, the frequency difference Δf ₁₁ of the reflected light detected at each position when the steel plate P is changed in advance by a predetermined distance change amount d, and the distance change amount d of the steel plate P when the position is changed. A constant k obtained by the formula k=Δf ₁₁ /d, which shows the relationship, may be stored in advance and used.

As described above, the speed measuring device 31 can simultaneously measure the speed V of the steel plate P using the laser beam used when measuring the distance to the steel plate P. FIG. Therefore, the speed measuring device 31 according to the second embodiment can measure the speed V of the steel plate P and simultaneously measure the distance to the steel plate P in a series of processes.

(3) <Other embodiments>
The present invention is not limited to this embodiment, and various modifications can be made within the scope of the present invention. For example, although a plate-shaped steel plate P is used as an object to be measured, the present invention is not limited to this, and objects to be measured of various shapes such as a steel plate having a shape such as a rectangular parallelepiped, a cylindrical steel material, and the like. You can apply things. Also, an object to be measured made of a material other than a steel plate may be applied.

Further, in the above-described embodiment, the case where the first measurement light and the second measurement light are generated using one laser oscillator 2 has been described, but the present invention is not limited to this, and the first measurement light is generated. A first laser oscillator and a separate second laser oscillator for generating the second measurement light may be provided.

In the above-described embodiment, the object to be measured moves at a predetermined position relative to the emission positions of the first measurement light and the second measurement light. (ie, the first measuring head 5a and the second measuring head 5b) are fixed, but the present invention is not limited to this. For example, the steel plate P may be fixed at a predetermined position, and each emission position of the first measurement light and the second measurement light may be moved along the moving direction X.

Further, in the above-described embodiment, the case where the object to be measured is at the reference position and is stationary with respect to the emission positions of the first measurement light and the second measurement light has been described. Not exclusively. For example, while moving the steel plate P at a predetermined speed V, each emission position may also be moved at a speed V in the same direction so that the steel plate P is relatively stationary.

Further, in the above-described embodiment, the first frequency analysis unit 17a and the second frequency analysis unit 17b are applied as the frequency analysis unit, and the first reference frequency acquisition unit 18a and the second reference frequency acquisition unit 18b are applied as the reference frequency acquisition unit. is applied, the first frequency difference calculation unit 19a and the second frequency difference calculation unit 19b are applied as the frequency difference calculation unit, and the first optical axis angle acquisition unit 20a and the second optical axis angle acquisition unit are applied as the optical axis angle acquisition unit 20b is applied and two of each are provided. It is also possible to process

Further, in the above-described embodiment, the emission positions of the first measurement light and the second measurement light are fixed, and the steel plate P is moved along the direction Z perpendicular to the moving direction X of the steel plate P by the distance change amount d. Although the case has been described, the present invention is not limited to this. For example, the position of the steel plate P may be fixed, and the emission positions of the first measurement light and the second measurement light may be moved along the direction Z perpendicular to the moving direction X by the distance change amount d.

A first measurement head 5a and a second measurement head 5b are separately provided, and the first measurement light is irradiated from the first measurement head 5a, and the second measurement is performed from the second measurement head 5b separately provided. Although the case of irradiating light has been described, the present invention is not limited to this. For example, one measuring head is provided, and after irradiating the steel sheet P with the first measuring light from the measuring head set to the _first optical axis angle θ1, the angle of the measuring head is changed to set the _second optical axis angle θ2. The steel plate P may be irradiated with the second measurement light from the measuring head. Even if the same measurement head is used to irradiate the first measurement light and the second measurement light at different irradiation timings, the same processing as in the above-described embodiment can be performed. Therefore, one measuring head may be used as both the first measuring head 5a and the second measuring head 5b.

Further, in the above-described embodiment, the FSF laser is used as the laser oscillation unit that oscillates laser light modulated by a predetermined amount of frequency change with respect to time, but the present invention is not limited to this. A variety of laser oscillators, such as a wavelength tunable semiconductor laser whose frequency can be modulated by an injection current, may be used as long as they can oscillate a laser beam whose frequency is modulated by an injection current.

Further, in the above-described embodiment, a beat signal having a frequency equal to the frequency difference between the reflected light and the reference light (for example, the first reflected light and the first reference light) is detected, and using this beat frequency, the steel plate P Although the distance to and the speed at which the steel plate P moves are measured, the present invention is not limited to this. For example, as disclosed in Japanese Patent Application Laid-Open No. 2016-80409, a reflection source is provided in the first measurement head and the second measurement head, and the measurement light is reflected by the reflection source to generate return light, and the reflected light and The frequency of the beat signal of the reference light and the frequency of the beat signals of the return light and the reference light are measured, and the difference between the two beat frequencies is used instead of the beat frequency to move the distance to the steel plate P and the steel plate P. Velocity may be measured.

Further, in the second embodiment described above, the arithmetic processing unit 32 has the distance calculation unit 18 and the distance change amount calculation unit 23 as elements for calculating the distance, but both are not necessary. It is also possible to omit the distance calculator 18 .

Next, the speed V and the amount of change in distance d were examined with θ ₁ =θ ₂ =θ in the above formulas (3) and (4). Assuming that θ ₁ =θ ₂ =θ in the above formulas (3) and (4), the following formulas (5) and (6) can be obtained.

V=(λ/4sinθ)・(−Δf ₁ +Δf ₂ ) …(5)
d=(cosθ/2k)・(Δf ₁ +Δf ₂ ) …(6)

In this case, the velocity V and the distance change amount d can be calculated by multiplying the difference and the sum (average) of the frequency change amounts by a constant, respectively, and can be expressed by a simpler formula. Therefore, when calculating the velocity V and the amount of change in distance d by the distance measuring method of the present invention, it can be seen that the evaluation is facilitated by setting θ ₁ =θ ₂ =θ.

The laser oscillator used as an example had a wavelength λ of FSF laser light of 1550 nm, and a constant k indicating the relationship between frequency and distance was about 44 MHz/m. θ was set to 5 degrees. Further, here, the first frequency difference calculator 19a and the second frequency difference calculator 19b of FIG. 5 are provided with frequency detectors each having a detection range of 40 MHz or less and a resolution of about 1 kHz.

In this case, if the first frequency difference Δf ₁ is 3 MHz and the second frequency difference Δf ₂ is 2.5 MHz, the velocity V is -2.2 m/s from the above equation (5), and the above equation (6) Therefore, the distance change amount d was 62 mm. Also, when the first frequency difference Δf ₁ was -1.6 MHz and the second frequency difference Δf ₂ was -1.5 MHz, the velocity V was 0.4 m/s and the distance variation d was -35 mm. From the above, it has been confirmed that it is possible to determine in which direction the steel plate P is moving in the moving direction X of the steel plate P.

Next, as shown in _FIG . 7, a _disc rotating device having a cylindrical object P2 to be measured and _rotating the object P2 to be measured around the central axis of the object P2 to be measured is prepared. did. Then, in order to confirm the effect of the present invention, a distance and speed measurement test was carried out using this disc rotating device and the speed measuring device 31 of the present invention. Although _FIG . 7 shows the fan _- shaped measured object P2, this only shows a partial cross section of the cylindrical measured object P2.

In this case, the first measuring head 25a and the _second measuring head 25b are fixed side by side on the same base (not shown) so that the base can move in the direction perpendicular to the circumferential surface of the object to be measured P2. made it Thus, by moving the base in the vertical direction, the first measuring head 25a and the second measuring head 25b can be moved in the vertical direction at the same time, and the distance change amount d can be adjusted.

A lens with a focal length of 300 mm was used for each of the first measurement head 25a and the second measurement head 25b. Therefore, a position about 300 mm from the circumferential surface of the object to be measured P2 was used as the reference position of the first measuring head 25a and the _second measuring head 25b. Then, while changing the rotation speed of the object to be measured P2, the first measuring head 25a and the _second measuring head 25b are vertically moved from the reference position, and the first measuring head 25a and the second measuring head 25b are moved several times. The velocity V and the amount of change in distance d were measured by changing the positions one by one.

First, calibration of constant k, first optical axis angle θ ₁ , and second optical axis angle θ ₂ performed before measurement will be described. Regarding the constant k, the positions of the first measuring head 25a and the second measuring head 25b are sequentially changed in the vertical direction, and the first reflected light or the second reflected light (reflected light) detected by the first measuring head 25a or the second measuring head 25b is The amount of change in the frequency of light) was investigated. Then, the change amount of the distance change amount d of the first measuring head 25a or the second measuring head 25b and the first reflected light or second reflected light (reflected light) detected by the first measuring head 25a or the second measuring head 25b When the constant k was calculated from the amount of change in the frequency of , the constant k was calculated to be 43.14 MHz/m.

Next, the _first optical axis angle θ1 and the _second optical axis angle θ2 were calculated. Here, the first measuring head 25a and the _second measuring head 25b are fixed at the reference position, the rotation speed of the object P2 is changed, and the first measuring head 25a and the second measuring head 25b respectively detect the Changes in the frequencies of the first reflected light and the second reflected light were investigated.

The amount of change in rotational speed (velocity V _D1 ) of the object to be measured P2 when the first measuring head 25a and the _second measuring head 25b are fixed at the reference position, and the amount of frequency change Δf ₂₁ of the first reflected light. Then, the first optical axis angle θ ₁ was calculated using the formula Δf ₂₁ =2V _D1 sin θ ₁ /λ. Also, the amount of change in the rotational speed (velocity V _D1 ) of the object P2 to be measured when the first measuring head 25a and the _second measuring head 25b are fixed at the reference position, and the amount of change in the frequency of the second reflected light Δf ₂₂ , the second optical axis angle θ ₂ was calculated using the formula Δf ₂₂ =2V _D1 sin θ ₂ /λ. Note that the wavelength λ of the laser light is 1550 nm as in the above case.

As a result, the _first optical axis angle θ1 was calculated to be 7.71 degrees, and the _second optical axis angle θ2 was calculated to be 6.69 degrees. Here, when installing the first measuring head 25a and the _second measuring head 25b, the vertical direction (perpendicular to the horizontal direction) extending from the center of the object to be measured P2 and the optical axis of the first measurement light The first optical axis angle θ ₁ formed by _ax1 should be set to about 5 degrees, and the vertical direction extending from the center of the object P2 to be measured and the optical axis _ax2 of the _second measurement light are formed. The _second optical axis angle θ2 should also have been set to about 5 degrees.

However, from the above calculation results, it can be inferred that the _first optical axis angle θ1 is not set to 5 degrees, but is actually set to 7.71 degrees. Similarly, it can be assumed that the _second optical axis angle θ2 is not set to 5 degrees but is actually set to 6.69 degrees. As for the mounting accuracy, the optical axis _ax1 of the first measurement light and the optical axis _ax2 of the second measurement light may be tilted by about 7.71 degrees and about 6.69 degrees as obtained above. is quite conceivable.

Next, the measured value of the distance change amount when the first measuring head 25a and the _second measuring head 25b are moved along the vertical direction from the object to be measured P2, and the distance measurement calculated from the above equation (4) A verification test was conducted to compare the value (distance change amount d).

In this verification test, the first measuring head 25a and the _second measuring head 25b are moved in the vertical direction, the rotational position of the object P2 to be measured with respect to the first measuring head 25a and the second measuring head 25b is changed, and each position , the _first frequency difference Δf1 and the _second frequency difference Δf2 were calculated.

Specifically, the object to be measured P2 was held stationary at the reference position, and the _average value of the frequencies for 1S (1000 points) of the first reflected light and the second reflected light was calculated. In addition, the first measurement head 25a and the second measurement head 25b were moved vertically while rotating the object P2 to be measured at a predetermined speed V. _FIG . Then, the first measuring head 25a and the second measuring head 25b are fixed at several positions, and the average value of the frequencies for 1S (1000 points) of the first reflected light and the second reflected light is calculated for each position. Calculated.

When the object to be measured P2 is stationary at the reference position, and when the positions of the first measuring head 25a and the _second measuring head 25b are changed with respect to the _rotating object to be measured P2. , the frequency difference of the first reflected light (first frequency difference Δf ₁ ) and the frequency difference of the second reflected light (second frequency difference Δf ₂ ) are calculated from the positions of the first measuring head 25a and the second measuring head 25b. calculated for each.

Then, the constant k, the first optical axis angle θ ₁ , the second optical axis angle θ ₂ , the first frequency difference Δf ₁ obtained for each position, and the second frequency obtained for each position are obtained as described above. Using the difference Δf ₂ , the distance change amount d was calculated from the above equation (4). In addition, a laser rangefinder was prepared separately from the speed measuring device 31, and the amount of change in distance from the reference position of the first measuring head 25a and the second measuring head 25b was measured as an actual measurement value.

Figure 8A summarizes these results. The vertical axis of FIG. 8A indicates the distance measurement value (distance change amount d) calculated from the above equation (4). The vertical axis of _FIG . 8A represents the above equation ( The distance measurement value (distance change amount d) calculated from 4) is used as a reference.

The horizontal axis of FIG. 8A indicates the measured values of the distance variation of the first measuring head 25a and the second measuring head 25b measured by the FSF laser rangefinder. In FIG. 8A, the positive direction is the direction in which the first measuring head 25a and the _second measuring head 25b move away from the object to be measured P2. As shown in FIG. 8A, the results on the vertical axis and the horizontal axis were in general agreement.

Next, in order to confirm the details, the result (distance measurement value error) was examined by subtracting the value of the horizontal axis of FIG. 8A from the value of the vertical axis of FIG. 8A, and the result shown in FIG. 8B was obtained. rice field. From FIG. 8B, the average distance measurement error was −0.087 mm, and the variation was 1σ=0.19 mm. From these results, when compared with the accuracy of the FSF laser rangefinder, the measurement result of the distance change amount d calculated by the speed measuring device 31 of the present invention is slightly lower, but the variation due to the difference in speed is 1σ=0 at the maximum. It was about 0.037 mm, and it was confirmed that an accuracy equivalent to that of the FSF laser rangefinder could be obtained.

Next, a verification test was conducted to compare the measured value of the speed at which the object P2 to be measured rotates with the speed V calculated from the above equation ( ₃ ). Here, the first measuring head 25a and the _second measuring head 25b were fixed at the reference position, and the speed at which the object P2 to be measured rotates at the reference position is changed. Then, the wavelength λ of the laser beam, the first optical axis angle θ ₁ , the second optical axis angle θ ₂ , the first frequency difference Δf ₁ obtained for each speed, and the Using the _second frequency difference Δf2, the velocity V was calculated from the above equation (3).

Further, the speed was calculated from the _number of revolutions of the object P2 to be measured and the diameter of the object P2 to be measured for _each speed, and these were obtained as actual measurement values. Figure 9A summarizes these results. _The horizontal axis of _FIG . 9A is the actually measured value of the rotation speed of the object P2 to be measured, which indicates the speed calculated from the _number of rotations of the object P2 to be measured and the diameter of the object P2 to be measured. The horizontal axis of FIG. 9A assumes the clockwise direction of FIG. 7 to be positive. On the other hand, the vertical axis of FIG. 9A is the velocity V calculated from the above equation (3). As shown in FIG. 9A, the results on the vertical axis and the horizontal axis were in general agreement.

Next, in order to confirm the details, the value on the horizontal axis in FIG. 9A was subtracted from the value on the vertical axis in FIG. 9A, and the result was divided by the value on the horizontal axis. The results shown were obtained. From FIG. 9B, the velocity measurement error was within ±0.5% error. As described above, it was confirmed that the velocity V can be accurately obtained from the above equation ( ₃ ) simply by changing the velocity V of the object P2 to be measured at the reference position.

Next, the first measuring head 25a and the second measuring head 25b were moved from the reference position by -50 mm, -100 mm, 50 mm, and 100 mm, and the positions of the first measuring head 25a and the second measuring head 25b were changed. 9C, 10A, 10B, and 10C when the rotational speed of the object P2 to be measured was changed for _each position and the speed measurement error was examined for each position in the same manner as in FIG. 9B. The results shown in are obtained.

FIG. 9C shows the result when the amount of change in distance from the reference position is −50 mm, and FIG. 10A shows the result when the amount of change in distance from the reference position is −100 mm. FIG. 10B shows the results when the amount of change in distance from the reference position is 50 mm, and FIG. 10C shows the results when the amount of change in distance from the reference position is 100 mm. From FIGS. 9C, 10A, 10B, and 10C, many values were within the error of ±0.5% in the distance variation range of ±100 mm. Therefore, it has been confirmed that the velocity V can be measured with high accuracy over a wide range when compared with the measured values.

(4) <Third Embodiment>
(4-1) <About the speed measuring device according to the third embodiment>
Next, as a third embodiment, as shown in FIG. 11, a velocity measuring device 51 having a first measuring head 5a, a second measuring head 5b and a third measuring head 5c will be described below. The speed measuring device 51 of the third embodiment first defines an arbitrary direction along the measurement surface S as a reference direction in the surface direction of the measurement surface S of the steel plate P, and a line extending in this reference direction is set as the reference line.

The speed measuring device 51 defines an arbitrary reference direction in which the reference line is set as a first movement direction X, and defines a direction perpendicular to the first movement direction X as a second movement direction Y in the surface direction of the measurement surface S. do. The speed measuring device 51 measures the relative speed VX of the steel plate P with respect to the first measuring head 5a, the second measuring head 5b, and the third measuring head 5c in the first moving direction _X , and the second moving direction Y , the relative velocity _VY of the steel plate P with respect to the first measuring head 5a, the second measuring head 5b and the third measuring head 5c is measured.

The speed measuring device 51 vector-synthesizes the speed VX, which is the first moving direction _X component of the speed V, and the speed VY, which is the second moving direction _Y component of the speed V, and obtains the speed V and the moving direction of the steel plate P. Find a composite vector that indicates . The speed measuring device 51 of the third embodiment can measure the speed V of the steel plate P from the magnitude of the composite vector, and can measure the moving direction of the steel plate P from the direction of the composite vector. Note that the magnitude of the speed V of the steel plate P is the square root of the sum of the squares of the value of the speed V _X and the value of the speed V _Y (that is, √{(V _X ) ² +(V _Y ) ² }), The moving direction of the steel plate P is a direction deviated from the reference line by an angle defined by arctan (Vy/Vx).

Here, the speed measuring device 51 has a laser oscillator 2 that oscillates laser light modulated at a predetermined frequency modulation speed with respect to time. , and further transmit part of the measurement light to the first measurement head 5a, the second measurement head 5b and the third measurement head 5c, respectively.

The first measuring head 5a and the second measuring head 5b provided in the velocity measuring device 51 of the third embodiment have the same configuration as in the above-described first embodiment, and the first moving direction X and the second The measurement surface S of the steel plate P moving at a predetermined speed V in the moving direction Y or the measurement surface S of the steel plate P at rest is irradiated with the first measurement light and the second measurement light.

The third measuring head 5c has the same configuration as the first measuring head 5a and the second measuring head 5b, and is part of the measuring light transmitted from the laser oscillator 2 via the optical fiber path. After the third measurement light is emitted from the end of the optical fiber optical path and condensed by a condensing lens, the measurement surface S of the steel plate P is irradiated with the light. The third measurement head 5c directs the third measurement light toward the measurement surface S of the steel plate P that is moving at a predetermined speed V in a predetermined movement direction or toward the measurement surface S of the steel plate P that is stationary. Irradiate.

The third reflected light obtained by reflecting the third measurement light from the measurement surface S of the steel plate P is guided to the coupler 6 and the splitter 3 in the same manner as the first reflected light and the second reflected light. A third reference light split from the laser light is also guided to the combiner 6 . The coupler 6 causes the third reference light and the third reflected light to enter the third photodetector 7c through optical fibers. The coupler 6 causes the first reference light and the first reflected light to enter the first photodetector 7a, respectively, and causes the second reference light and the second reflected light to enter the second photodetector 7b, respectively.

The third reflected light and the third reference light that enter the third photodetector 7c at the same time are the optical path lengths of the respective laser beams that travel from the laser oscillator 2 to the third photodetector 7c. , a beat signal is generated by optical interference between the third reflected light and the third reference light. The third photodetector 7c, like the first photodetector 7a and the second photodetector 7b, detects this beat signal and sends it to the arithmetic processing unit 33, which will be described later. Note that the first photodetector 7a and the second photodetector 7b are the same as those in the above-described first embodiment, and the description thereof will be omitted here to avoid redundancy.

In the third embodiment, the first measuring head 5a, the second measuring head 5b, and the third measuring head 5c are inclined, and the arithmetic processing unit 33 performs arithmetic processing according to a velocity measuring method described later. , the first beat frequency, the second beat frequency and the third beat frequency, it is possible to measure the velocity V when the steel plate P is moving in a predetermined moving direction.

(4-2) <Speed measurement method according to the third embodiment>
Next, a speed measuring method according to the third embodiment will be described with reference to FIGS. 11 and 12. FIG. In this velocity measurement method, a laser beam is used to measure a velocity VX in a first movement direction X, and a second movement direction Y perpendicular to the first movement direction _X is measured on a measurement plane S (that is, an XY plane). The moving direction of the steel plate P and its speed V can be measured by also measuring the speed _VY of and combining these speeds _VX and _VY . In the speed measurement method, three of a first measurement head 5a, a second measurement head 5b, and a third measurement head 5c are used, and the measurement surface S of the steel plate P is irradiated with the first measurement light from the first measurement head 5a. The measurement surface S of the steel sheet P is irradiated with the second measurement light from the second measurement head 5b, and the measurement surface S of the steel sheet P is irradiated with the third measurement light from the third measurement head 5c.

The first measuring head 5a, the second measuring head 5b, and the third measuring head 5c are arranged at different positions with respect to the steel plate P, and the optical axis a _x1 of the first measuring light emitted from the first measuring head 5a (a first optical axis angle θ ₁ to be described later), an inclination of the optical axis _ax2 of the second measurement light emitted from the second measuring head 5b (a second optical axis angle θ ₂ to be described later), and a third The inclination of the optical axis _ax3 of the third measurement light emitted from the measurement head 5c (a third optical axis angle θ ₃ to be described later) is set at a predetermined angle. The _first optical axis angle .theta.1, the _second optical axis angle .theta.2 and the _third optical axis angle .theta.3 may be the same angle or may be different angles.

Here, in the third embodiment, the inclination (first optical axis angle θ ₁ ) of the optical axis _ax1 of the first measurement light emitted from the first measurement head 5a means the first movement direction X and the second It is the angle formed between the direction Z of the surface normal to the measurement surface S perpendicular to the moving direction Y and the optical axis _ax1 of the first measurement light. Further, in the third embodiment, the inclination (second optical axis angle θ ₂ ) of the optical axis _ax2 of the second measurement light emitted from the second measurement head 5b means the first movement direction X and the second movement direction X It is the angle formed by the direction Z of the surface normal to the measurement surface S perpendicular to the direction Y and the optical axis _ax2 of the second measurement light. Furthermore, the inclination of the optical axis _ax3 of the third measurement light emitted from the third measurement head 5c (third optical axis angle θ ₃ ) means This is the angle formed by the direction Z of the surface normal of S and the optical axis _ax3 of the third measurement light.

In FIG. 11, in the direction Z along the surface normal to the first moving direction X and the second moving direction Y of the steel plate P, the difference in distance between the steel plate P at the predetermined position and the steel plate P1 at the reference position is the distance change amount d. Note that in FIG. 11, as an example of the steel plate P1 at the reference position, the steel plate P in the moving state has a direction Z along a plane normal perpendicular to the first moving direction X and the second moving direction Y , the steel plate P1 moved by the distance change amount d in a direction approaching the first measuring head 5a, the second measuring head 5b and the third measuring head 5c.

FIG. 12 shows the first measuring head 5a, the second measuring head 5b when looking at the first measuring head 5a, the second measuring head 5b and the third measuring head 5c from above the steel plate P (i.e. along the direction Z). and a schematic diagram showing the positional relationship of the third measuring head 5c. In this case, the projection a _x1 ′ of the optical axis a _x1 of the first measuring head 5a onto the measuring plane S, which is a moving plane including the first moving direction X and the second moving direction Y of the steel plate P, and the measurement of the steel plate P The angle formed on the measurement plane S by a reference line a _Φ extending in the reference direction (here, the first moving direction X) defined by the surface direction of the surface S is defined as a first projection angle Φ ₁ . The angle formed on the measurement surface S by the projection a _x2 ′ of the optical axis a _x2 of the second measurement head 5b onto the measurement surface S and the reference line a _Φ is defined as a second projection angle Φ ₂ . Further, the angle formed on the measurement surface S by the projection _ax3 ' of the optical axis _ax3 of the third measurement head 5c onto the measurement surface S and the reference line _aΦ3 is defined as a _third projection angle Φ3.

In this embodiment, the first movement direction X is applied as the reference line _aΦ extending along the surface direction of the measurement surface S, and the angle formed on the measurement surface S by the projection _ax1 ′ and the first movement direction X is a first projection angle Φ ₁ , the angle between the projection a _x2 ' and the first movement direction X on the measurement plane S is a second projection angle Φ ₂ , and the projection a _x3 ' and the first movement direction X are measured Although the angle formed on the plane S is the _third projection angle Φ3, the present invention is not limited to this case. For example, as the reference line a _Φ extending along the surface direction of the measurement surface S, the second movement direction Y or any other direction in the surface direction of the measurement surface S is set as the reference direction, and the reference line extending in this reference direction is May be applied to define a first projection angle Φ ₁ , a second projection angle Φ ₂ and a third projection angle Φ ₃ . In addition, as shown in FIG. 12, the first projection angle Φ ₁ , the second projection angle Φ ₂ and the third projection angle Φ ₃ defined counterclockwise from the reference line a _Φ do not have to be, and the reference line a _Φ may be a first projection angle Φ ₁ , a second projection angle Φ ₂ and a third projection angle Φ ₃ defined clockwise from .

In this case, a first beat frequency (first reference frequency) obtained from the first reflected light and the first reference light reflected from the measurement surface S of the steel plate P1 which is stationary at the reference position, and Letting Δf1 be the frequency difference ( _first frequency difference) between the first reflected light reflected from the measurement surface S of the steel plate P in the state and the first beat frequency obtained from the first reference light, The _first frequency difference Δf1 of the third embodiment is affected by the distance change amount d and the Doppler shift, and can be expressed by the following equation (7).

Δf ₁ =k(d/cos θ ₁ ) + ((2V _X cos Φ ₁ sin θ ₁ )/λ) + ((2V _Y sin Φ ₁ sin θ ₁ )/λ)) … (7)

θ ₁ indicates the above-described first optical axis angle, Φ ₁ indicates the above-described first projection angle, and λ indicates the wavelength of the laser. For example, k is a constant that indicates the relationship between the change in the distance of the steel plate P from the first measuring head 5a, the second measuring head 5b, and the third measuring head 5c and the change in the frequency of the laser light.

In the above formula (7), the first term indicates the amount of change in frequency of the laser light (first reflected light) due to the change in the distance from the first measuring head 5a to the steel plate P. On the other hand, the second term of the above equation (7) indicates that when the steel plate P moves in a predetermined moving direction, the laser light (first The third term indicates the amount of change in the frequency of the reflected light), and the third term indicates the amount of change in frequency in the second moving direction Y perpendicular to the first moving direction X on the measurement plane S when the steel plate P moves in a predetermined moving direction. This term indicates the amount of frequency change of the laser light (first reflected light) due to the influence of the Doppler shift of .

Further, the second beat frequency (second reference frequency) obtained from the second reflected light reflected from the measurement surface S of the steel plate P1 which is stationary at the reference position and the second reference light, and the moving state at the predetermined position. Let Δf2 be the frequency difference ( _second frequency difference) between the second reflected light reflected from the measurement surface S of the steel plate P at the position and the second beat frequency obtained from the second reference light. The _second frequency difference Δf2 of the third embodiment is affected by the distance change amount d and the Doppler shift, so it can be expressed by the following equation (8).

Δf ₂ =k(d/cos θ ₂ ) + ((2V _X cos Φ ₂ sin θ ₂ )/λ) + ((2V _Y sin Φ ₂ sin θ ₂ )/λ)) (8)

Further, a third beat frequency (third reference frequency) obtained from the third reflected light reflected from the measurement surface S of the steel plate P1 in a stationary state at the reference position and the third reference light, and a moving state at the predetermined position If the frequency difference (third frequency difference) between the third reflected light reflected from the measurement surface S of the steel plate P at the position and the third beat frequency obtained from the third reference light is Δf3, then the _third The third frequency difference Δf ₃ of the third embodiment is affected by the distance change amount d and the Doppler shift, so it can be expressed by the following equation (9).

Δf ₃ =k(d/cos θ ₃ ) + ((2V _X cos Φ ₃ sin θ ₃ )/λ) + ((2V _Y sin Φ ₃ sin θ ₃ )/λ)) … (9)

Since the first measuring head 5a, the second measuring head 5b, and the third measuring head 5c have the same configuration, the constant k in equations (8) and (9) is It is the same as the expression (7) for 5a.

Also in the third embodiment, similarly to the above-described first embodiment, the calculation of the first frequency difference Δf ₁ , the second frequency difference Δf ₂ and the third frequency difference Δf ₃ is based on the reference It is not necessary to use the first beat frequency, the second beat frequency and the third beat frequency detected when the steel plate P is relatively stationary at the position. For example, using the first beat frequency, the second beat frequency, and the third beat frequency detected when the steel plate P is moving at the reference speed at the reference position, the steel plate P is moving at a predetermined position at a speed other than the reference speed. A first frequency difference Δf ₁ , a second frequency difference Δf ₂ and a third frequency difference Δf ₃ are calculated from the differences between the first beat frequency, the second beat frequency and the third beat frequency detected at the time. good too.

From the above equations (7), (8), and (9), the velocity VX generated in the first moving direction _X when the steel plate P moves in the predetermined moving direction can be calculated. Equation (10) below can be derived.

_VX = (A1・₍ D2・C3 _{－ C2}・_D3 )＋C1・_{( A2}・_{D3 －} D2・A3) _＋ D1・_{( C2}・A3 _{－ A2}・_{C 3} ))/ ₍ A1・_{( C2}・_{B3 －} B2・C3)
＋B ₁・(A ₂・C ₃ −C ₂・A ₃ )＋C ₁・(B ₂・A ₃ −A ₂・B ₃ )) …（１０）

A _i , B _i , C _i and D _i (i=1, 2, 3) in the above formula (10) are represented by the following formulas.
Ai = k/ _cosθi ( _i =1,2,3)
B _i =(2 cos φ _i sin θ _i )/λ (i=1,2,3)
Ci=( _{2sinφi sinθi} )/λ ( _i =1,2,3)
D _i ＝−Δf _i (i=1,2,3)

Here, the wavelength λ of the laser light can be obtained by measuring in advance using a spectroscope or the like. For the constant k in the above formula (10), similarly to the above-described first embodiment, for example, the distance change amount d is provided, the steel plate P is stopped at different positions, and the steel plate P at each position is The frequency of the first reflected light (or second reflected light or third reflected light) is measured, and the frequency change amount and distance of the first reflected light (or second reflected light or third reflected light) at this time It can be calculated based on the equation k=Δf ₁₁ /d from the amount of change d. It is also possible to obtain k from the equation k=2r _s /c (r _s is the frequency modulation speed and c is the speed of light in air).

In the above equation (10), the first optical axis angle θ ₁ and the first projection angle Φ ₁ change the speed V at which the steel plate P moves at the same position, and the first reflected light reflected from the steel plate P and the first reflected light The first beat frequency obtained from the first reference beam was measured at each speed. It can be calculated from the difference in velocity _VX and the difference in velocity VY in the second moving direction _Y.

Specifically, the first optical axis angle θ ₁ and the first projection angle Φ ₁ can be calculated using the second and third terms of Equation (7) above. For example, first, the steel plate P is moved at a plurality of velocities V _X1 and V _X2 along the first moving direction X as the reference direction at the same position, and each detected at each of these velocities V _X1 and V _X2 The difference between the first beat frequencies is calculated as the frequency difference Δf _X31 . Also, the speed difference between the speeds V _X1 and V _X2 is calculated as the speed V _XD1 for calibration.

As a result, the following equation (12) can be derived from the second term of the above equation (7) using the wavelength λ of the laser light, the velocity V _XD1 for calibration, and the frequency difference Δf _X31 .

Δf _X31 =2V _XD1 · _cosΦ1 ·sin θ1 _/ λ (12)

Next, at the same position, the steel plate P is moved along the second moving direction _Y perpendicular to the first moving direction X in the plane direction of the measurement surface S at a plurality of velocities V _Y1 and V _Y2 . A difference between the respective first beat frequencies detected at _VY2 is calculated as a frequency difference _ΔfY31 . Also, the speed difference between the speeds V _Y1 and V _Y2 is calculated as the speed V _YD1 for calibration.

As a result, the following equation (13) can be derived from the third term of the above equation (7) using the wavelength λ of the laser light, the velocity V _YD1 for calibration, and the frequency difference Δf _Y31 .

Δf _Y31 =2V _YD1 · _sinΦ1 ·sin θ1 _/ λ (13)

Therefore, the first optical axis angle θ ₁ and the first projection angle Φ ₁ can be calculated from the above equations (12) and (13).

Regarding the _second optical axis angle θ2 and the _second projection angle Φ2, similarly to the _first optical axis angle θ1 and the _first projection angle Φ1, the steel plate P moving at the same position in the first moving direction X The speed VX and the speed _VY in the second movement direction _Y were changed, and the second beat frequency obtained from the second reflected light reflected from the steel plate P and the second reference light was measured at each speed. , can be calculated from the amount of change in the second beat frequency at this time, the difference in velocity _VX , and the difference in velocity _VY .

Specifically, the second optical axis angle θ2 and the _second projection angle Φ2 can be calculated using the _second and third terms of Equation (8) above. That is, the steel plate P is moved at the same position along the first movement direction _X at a plurality of velocities VX1 and _VX2 , and the difference between the second beat frequencies detected at these velocities _VX1 and _VX2 is The frequency difference Δf is calculated as _X41 .

Then, using the velocity _VXD1 for calibration, which is the velocity difference between the velocities _VX1 and _{VX2, the wavelength λ of the laser light, and the frequency difference ΔfX41 ,} from the second term of the above equation (8), the following Equation (14) can be derived.

Δf _{X41 =} 2V _XD1 · _cosΦ2 ·sin θ2/λ (14)

Similarly, the steel plate P is moved at the same position along the second movement direction Y at a plurality of velocities _VY1 and _VY2 , and the difference between the second beat frequencies detected at these velocities _VY1 and _VY2 is is calculated as the _frequency difference _{Δf Y41 ,} and the _above equation ( The following equation (15) can be derived from the third term of 8).

Δf _Y41 =2V _YD1 ·sin Φ ₂ ·sin θ ₂ /λ (15)

Therefore, the _second optical axis angle θ2 and the _second projection angle Φ2 can be calculated from the above equations (14) and (15).

Furthermore, for the third optical axis angle θ3 and the _third projection angle _Φ3 , similarly to the _first optical axis angle θ1 and the _first projection angle Φ1, the steel plate P moving at the same position is moved in the first moving direction X and the speed _VY in the second moving direction _Y are changed, and the third beat frequency obtained from the third reflected light reflected from the steel plate P and the third reference light is calculated at each speed as It can be calculated from the amount of change in the third beat frequency at this time, the difference in velocity _VX , and the difference in velocity _VY .

Specifically, the third optical axis angle θ3 and the _third projection angle Φ3 can be calculated using the second and _third terms of the above equation (9). That is, the steel plate P is moved at the same position along the first moving direction _X at a plurality of velocities VX1 and _VX2 , and the difference between the respective third beat frequencies detected at these velocities _VX1 and _VX2 is The frequency difference Δf is calculated as _X51 .

Then, using the velocity V _XD1 for calibration, which is the velocity difference between the velocities V _X1 and V _X2 , the wavelength λ of the laser light, and the frequency difference Δf _X51 , the following is obtained from the second term of the above equation (9): Equation (16) can be derived.

Δf _X51 =2V _XD1 · _cosΦ3 ·sin θ3/λ ₍ 16)

Similarly, the steel plate P is moved at the same position along the second movement direction Y at a plurality of velocities _VY1 and _VY2 , and the difference between the respective third beat frequencies detected at these velocities _VY1 and _VY2 is is calculated _as the _frequency difference _{Δf Y51 ,} and the above equation ( The following equation (17) can be derived from the third term of 9).

Δf _Y51 =2V _YD1 ·sin Φ ₃ ·sin θ ₃ /λ (17)

Therefore, the third optical axis angle θ3 and the _third projection angle _Φ3 can be calculated from the above equations (16) and (17).

From the above, in the above formula (10), the wavelength λ of the laser light, the constant k, the first optical axis angle θ ₁ , the second optical axis angle θ ₂ , the third optical axis angle θ ₃ , The _first projection angle Φ1, the _second projection angle Φ2, and the _third projection angle Φ3 can be obtained in advance. Therefore, by measuring the first frequency difference Δf ₁ , the second frequency difference Δf ₂ and the third frequency difference Δf ₃ , from the above equation (10), the moving steel plate P in the first moving direction X Velocity _VX can be calculated.

When constructing the speed measuring device 51, the first optical axis angle θ ₁ , the second optical axis angle θ ₂ , the third optical axis angle θ ₃ , the first projection angle Φ ₁ , and the second projection angle Φ ₂ and the third projection angle Φ ₃ are known, or if they are known by accurate measurement with a separate measuring instrument, the values can be used directly from the above equation (10) to obtain the velocity _VX can be calculated.

Furthermore, in addition to this, the velocity VY generated in the second moving direction _Y when the steel plate P moves in the predetermined moving direction is calculated from the above equations (7), (8) and (9). , the following equation (18) can be derived.

V _{Y =} -(A1・₍ D2・_{B3 -B2}・_D3 ) _{+ B1}・_{( A2}・_{D3 -D2}・A3) ₊ D1・₍ B2・A3 _-A2・B3)) _{/ (} A1・_{( C2}・_{B3 －} B2・C3)
+B ₁・(A ₂・C ₃ −C ₂・A ₃ )+C ₁・(B ₂・A ₃ −A ₂・B ₃ )) …（18）

A _i , B _i , C _i and D _i (i=1, 2, 3) in the above formula (18) are A _i , B _i , C _i and D _i ( i=1,2,3).

In the above equation (18), the wavelength λ of the laser light, the constant k, the _first optical axis angle θ1, the _second optical axis angle θ2, the _third optical axis angle θ3, and the first projection The angle Φ1, the _second projection angle Φ2, and the _third projection angle _Φ3 can be obtained in advance. Therefore, by measuring the first frequency difference Δf ₁ , the second frequency difference Δf ₂ and the third frequency difference Δf ₃ , the velocity V _Y can be calculated.

(4-3) <Regarding the processing unit>
Next, the arithmetic processing unit 33 that executes the speed measuring method according to the third embodiment described above will be described below. As shown in FIG. 13, the arithmetic processing unit 33 calculates the speed VX of the steel plate P in the first moving direction _X based on the above equation (10) without calculating the distance, and the above equation ( 18) can be used to measure the velocity VY of the steel sheet P in the second moving direction _Y , and the moving direction of the steel sheet P and its velocity V from the velocity VY. FIG. 13 is a block diagram showing the circuit configuration of the arithmetic processing unit 33, and the same components as those of the arithmetic processing unit 11 in FIG. 5 are denoted by the same reference numerals.

As shown in FIG. 13 , the arithmetic processing device 33 includes a frequency analysis section 17 , a distance calculation section 18 , a calculation section 34 , a constant acquisition section 14 and a wavelength acquisition section 16 . Here, points different from the above-described first embodiment will be mainly described, and descriptions of portions that overlap with the first embodiment will be omitted.

Since the third measuring head 5c is provided in the third embodiment, the frequency analysis unit 17 includes the first frequency analysis unit 17a and the second frequency analysis unit 17b, and the third frequency analysis unit 17c. is provided. The third frequency analysis unit 17c receives a beat signal generated by optical interference between the third reflected light and the third reference light from the third light detection unit 7c (FIG. 11), and the frequency of the beat signal (third beat frequency) is detected within a predetermined detection frequency range, and the detection results are sent to the distance calculation unit 18, the reference frequency acquisition unit 35, the frequency difference calculation unit 19, and the angle acquisition unit .

The calculator 34 includes a reference frequency acquirer 35 , a frequency difference calculator 19 , an angle acquirer 36 and a velocity calculator 38 .

The third reference frequency obtaining unit 18c provided in the reference frequency obtaining unit 35 obtains the third reference frequency used when obtaining the _third frequency difference Δf3 used in the above equations (10) and (18). to obtain. The third reference frequency acquisition unit 18c stores the third beat frequency in the stationary state and the reference position received from the third frequency analysis unit 17c, that is, the third reference frequency. The third reference frequency acquisition unit 18c sends the third reference frequency to the third frequency difference calculation unit 19c.

In addition to the _third frequency difference Δf3 used in the above equations (10) and (18), the third frequency difference calculator 19c calculates the third optical axis angle θ3 and the _third projection angle Φ as necessary. ₃ is calculated to calculate the third frequency difference. The third frequency difference calculator 19c is connected to the third photodetector 7c (FIG. 11) via the third frequency analyzer 17c, and detects the moving steel plate detected by the third photodetector 7c. A signal indicative of a third beat frequency associated with P is received. Also, the third frequency difference calculator 19c is connected to the third reference frequency acquisition unit 18c and receives a signal indicating the third reference frequency.

As a result, the third frequency difference calculator 19c calculates the difference between the third beat frequency detected from the moving steel plate P and the third reference frequency detected from the steel plate P stationary at the reference position as the third frequency. The difference Δf is calculated as ₃ . The third frequency difference calculator 19c sends information indicating the _third frequency difference Δf3, which is the calculation result, to the speed calculator 38 .

The angle acquisition section 36 has an optical axis angle acquisition section 20 and a projection angle acquisition section 37 . The third optical axis angle acquisition section 20c of the optical axis angle acquisition section 20 acquires the _third optical axis angle θ3 used in the above equations (10) and (18). The third optical axis angle acquisition unit 20c may calculate the _third optical axis angle θ3 by arithmetic processing, or measure the _third optical axis angle θ3 by the measurement means to acquire the measured value. Alternatively, the _third optical axis angle θ3 may simply be stored in advance. The third optical axis angle acquisition unit 20c sends information indicating the _third optical axis angle θ3 to the velocity calculation unit 38. FIG.

The projection angle acquisition unit 37 includes a first projection angle acquisition unit 37a, a second projection angle acquisition unit 37b, and a third projection angle acquisition unit 37c. The first projection angle acquisition unit 37a acquires the _first projection angle Φ1 used in the above equations (10) and (18), and the second projection angle acquisition unit 37b acquires the above equation (10 ) and equation (18), and the third projection angle acquisition unit 37c acquires the _third projection angle Φ used in equations (10) and (18) above. ₃ is obtained.

The first projection angle acquisition unit 37a, the second projection angle acquisition unit 37b, and the third projection angle acquisition unit 37c obtain the first projection angle Φ ₁ , the second projection angle Φ ₂ , and the third projection angle Φ ₃ by arithmetic processing, respectively. Alternatively, the first projection angle Φ ₁ , the second projection angle Φ ₂ and the third projection angle Φ ₃ may be measured by a measuring means to obtain actual measured values, and the first projection angle The angle Φ ₁ , the second projection angle Φ ₂ and the third projection angle Φ ₃ may simply be stored in advance. The first projection angle acquisition unit 37a, the second projection angle acquisition unit 37b, and the third projection angle acquisition unit 37c obtain information indicating the first projection angle Φ ₁ , the second projection angle Φ ₂ , and the third projection angle Φ ₃ as the velocity. It is sent to the calculator 38 .

Here, for example, when the first optical axis angle θ ₁ and the first projection angle Φ ₁ are calculated by conducting an actual test, the steel plate P is moved at the same position along the first moving direction X at a plurality of speeds V The first beat frequencies detected at the _{velocities V X1 and V X2 are sent from} the first frequency analysis section 17a to the first frequency difference calculation section 19a. At the same position, the steel plate P is moved along the second moving direction Y at a plurality of velocities _VY1 and _VY2 , and each of the first beat frequencies detected at these velocities _VY1 and _VY2 is It is sent from the frequency analysis unit 17a to the first frequency difference calculation unit 19a.

For example, the first frequency difference calculator 19a calculates the difference between the frequencies of the first beat frequencies at the velocities VX1 and VX2 in the first moving direction _X as the frequency difference _ΔfX31 , which is calculated as the frequency difference _ΔfX31 . It is sent to the angle acquisition unit 20a and the first projection angle acquisition unit 37a. The first optical axis angle acquisition unit 20a acquires the frequency difference Δf _X31 , the velocity V _XD1 for calibration indicating the velocity difference between the velocities V _X1 and V _X2 , and the wavelength λ. ) (ie, Δf _X31 =2V _XD1 ·cos Φ ₁ ·sin θ ₁ /λ).

Also, the first frequency difference calculator 19a calculates the frequency difference of the first beat frequency between the velocities V _Y1 and V _Y2 in the second movement direction Y as a frequency difference Δf _Y31 , which is calculated as the frequency difference Δf Y31. It is sent to the angle acquisition unit 20a and the first projection angle acquisition unit 37a. The first optical axis angle acquisition unit 20a acquires the frequency difference Δf _Y31 , the velocity V _YD1 for calibration indicating the velocity difference between the velocities V _Y1 and V _Y2 , and the wavelength λ. ) (ie, Δf _Y31 =2V _YD1 ·sin Φ ₁ ·sin θ ₁ /λ).

As a result, the first optical axis angle acquisition unit 20a obtains the second term (Δf _X31 =2V _XD1 ·cosΦ ₁ ·sin θ ₁ /λ) of formula (7) and the third term of formula (7) ( Δf _Y31 =2V _YD1 ·sin Φ ₁ ·sin θ ₁ /λ), the first optical axis angle θ ₁ is calculated. Specifically, Φ ₁ is eliminated from the above two equations, and from √{(Δf _X31 /V _XD1 ) ² +(Δf _Y31 /V _YD1 ) ² }=2·sin θ ₁ /λ, the first optical axis Calculate the angle _θ1 . If the _first projection angle Φ1 is known, it can be calculated using either or both of the above two equations.

Similarly, in the first projection angle acquisition unit 37a, the second term (Δf _X31 =2V _XD1 ·cosΦ ₁ ·sin θ ₁ /λ) of the above equation (7) and the second term of the above equation (7) The first projection angle Φ ₁ is calculated from the three terms (Δf _Y31 =2V _YD1 ·sin Φ ₁ ·sin θ ₁ /λ). Specifically, θ ₁ is eliminated from the above two equations, and the first projection angle φ ₁ is calculated from (Δf _Y31 /Δf _X31 )=(V _YD1 /V _XD1 )·tan φ ₁ . If the _first optical axis angle θ1 is known, it is calculated using either or both of the above two equations.

When the second optical axis angle θ ₂ and the second projection angle _{Φ 2} are also calculated by performing an actual _test , in the same manner as described above, The frequency difference Δf _X41 of the second beat frequency, the velocity V _XD1 for calibration indicating the velocity difference between the velocities V _X1 and V _X2 , and the wavelength λ are acquired, and the second optical axis angle acquisition unit 20b acquires the above (8) (ie, Δf _X41 =2V _XD1 ·cosΦ ₂ ·sin θ ₂ /λ). Also, a frequency difference Δf _Y41 of the second beat frequency between the velocities V _Y1 and V _Y2 calculated by the second frequency difference calculator 19b, a calibration velocity V _YD1 indicating the velocity difference between the velocities V _Y1 and V _Y2 , and the wavelength λ are acquired, and the third term of the above equation (8) (ie, Δf _Y41 =2V _YD1 ·sin Φ ₂ ·sin θ ₂ /λ) is derived by the second optical axis angle acquisition unit 20b.

As a result, the second optical axis angle acquisition unit 20b obtains the second term (Δf _X41 =2V _XD1 ·cosΦ ₂ ·sin θ ₂ /λ) of formula (8) and the third term of formula (8) ( Δf _Y41 =2V _YD1 ·sinΦ ₂ ·sin θ ₂ /λ), the second optical axis angle θ ₂ is calculated.

In addition, the second projection angle acquisition unit 37b obtains the second term (Δf _X41 =2V _XD1 ·cosΦ ₂ ·sin θ ₂ /λ) of the above equation (8) obtained in this way, and the above equation The second projection angle Φ ₂ is calculated from the third term (Δf _Y41 =2V _YD1 ·sin Φ ₂ ·sin θ ₂ /λ) of (8).

Furthermore, when the third optical axis angle θ ₃ and the third projection angle Φ ₃ are also calculated by performing an actual test, the velocities V _X1 and V The frequency difference Δf _X51 of the third beat frequency at _X2 , the velocity V _XD1 for calibration indicating the velocity difference between the velocities V _X1 and V _X2 , and the wavelength λ are acquired, and the third optical axis angle acquisition unit 20c acquires , leads to the second term of equation (9) above (ie, Δf _X51 =2V _XD1 ·cos Φ ₃ ·sin θ ₃ /λ). Also, a frequency difference Δf _Y51 of the third beat frequency between the velocities V _Y1 and V _Y2 calculated by the third frequency difference calculator 19c, a calibration velocity V _YD1 indicating the velocity difference between the velocities V _Y1 and V _Y2 , and the wavelength λ are acquired, and the third term of the above equation (9) (ie, Δf _Y51 =2V _YD1 ·sin Φ ₃ ·sin θ ₃ /λ) is derived by the third optical axis angle acquisition unit 20c.

As a result, the third optical axis angle acquisition unit 20c obtains the second term (Δf _X51 =2V _XD1 ·cosΦ ₃ ·sin θ ₃ /λ) of formula (9) and the third term of formula (9) ( Δf _Y51 =2V _YD1 ·sinΦ ₃ ·sin θ ₃ /λ), the third optical axis angle θ ₃ is calculated.

Further, the third projection angle acquisition unit 37c obtains the second term (Δf _X51 =2V _XD1 ·cosΦ ₃ ·sin θ ₃ /λ) of the above equation (9) obtained in this way, and the above equation The third projection angle Φ ₃ is calculated from the third term (Δf _Y51 =2V _YD1 ·sin Φ ₃ ·sin θ ₃ /λ) of (9).

The constant acquisition unit 14 acquires the constant k used in the above equations (10) and (18). The constant acquisition unit 14 may calculate the constant k by performing an actual test, as in the second embodiment described above, or may simply store the constant k in advance. . The constant acquisition unit 14 sends information indicating the constant k to the speed calculation unit 38 .

Here, the speed calculator 38 includes a first speed calculator 38a, a second speed calculator 38b, and a combined speed calculator 38c. The first velocity calculator 38a calculates the acquired first frequency difference Δf ₁ , second frequency difference Δf ₂ , third frequency difference Δf ₃ , first optical axis angle θ ₁ , second optical axis angle θ ₂ , Using the third optical axis angle θ ₃ , the first projection angle Φ ₁ , the second projection angle Φ ₂ , the third projection angle Φ ₃ , the constant k and the wavelength λ of the laser light, the calculation is performed based on the above equation (10) Processing is performed to calculate the velocity VX in the first moving direction _X. FIG.

The second velocity calculator 38b also calculates the acquired first frequency difference Δf ₁ , second frequency difference Δf ₂ , third frequency difference Δf ₃ , first optical axis angle θ ₁ , second optical axis angle θ ₂ , the third optical axis angle θ ₃ , the first projection angle Φ ₁ , the second projection angle Φ ₂ , the third projection angle Φ ₃ , the constant k, and the wavelength λ of the laser light, based on the above equation (18) Arithmetic processing is performed on the second movement direction _Y to calculate the velocity VY.

The composite speed calculator 38c obtains a composite vector from the speed VX calculated by the first speed calculator _38a and the speed _VY calculated by the second speed calculator 38b. That is, the combined speed calculator 38c calculates the square root of the sum of the squares of the speed VX in the first moving direction _X and the speed VY in the second moving direction _Y (√{( _VX ) ² +( _VY ) ² }) is calculated, the velocity V of the steel plate P is obtained, arctan (Vy/Vx) is calculated, and the direction shifted by arctan (Vy/Vx) from the reference direction (moving direction X here) is determined as the movement of the steel plate P Seek as a direction.

As described above, the speed measuring device 51 according to the third embodiment uses laser light to determine the direction of movement of the steel plate P and the The velocity V in the direction can be measured.

(5) <Fourth embodiment>
A fourth embodiment of the present invention will now be described in detail. In the following description, the same reference numerals are given to the same configurations as in the third embodiment, and duplicate descriptions will be omitted.

(5-1) <About the speed measuring device according to the fourth embodiment>
In the fourth embodiment, as shown in FIG. 11, a first measuring head 5a, a second measuring head 5b, and a third measuring head 5c are used as in the third embodiment. The velocity measuring device 52 according to the fourth embodiment measures the direction of movement of the steel plate P relative to the first measuring head 5a, the second measuring head 5b, and the third measuring head _5c and the velocity VX thereof. Furthermore, the difference in distance from the reference position to the steel plate P (distance change amount d) can also be measured simultaneously in a series of processes, which is different from the above-described third embodiment.

A speed measuring device according to the fourth embodiment differs from that of the above-described third embodiment in the configuration of an arithmetic processing unit 41, and other points are configured in the same manner as the third embodiment. Therefore, the following description will focus mainly on the arithmetic processing unit 41, which is different from the third embodiment.

(5-2) <Regarding the speed measurement method according to the fourth embodiment>
Here, when the distance change amount d of the steel plate P is calculated from the equations (7), (8), and (9) described in the third embodiment, it is expressed by the following equation (19). can be done.

d＝－( _B1・(D2・C3 _{－ C2}・_D3 ) _＋ C1・₍ B2・D3 _－ D2・_B3 ) _＋ D1・_{( C2}・_{B3 －} B2・_{C 3} ))/ ₍ A1・_{( C2}・_{B3 －} B2・C3)
＋B ₁・(A ₂・C ₃ −C ₂・A ₃ )＋C ₁・(B ₂・A ₃ −A ₂・B ₃ )) …（19）

A _i , B _i , C _i and D _i (i=1, 2, 3) in the above formula (19) are A _i , B _i , Same as C _i and D _i (i=1,2,3).

In the above equation (19), the wavelength λ of the laser light, the constant k, the _first optical axis angle θ1, the _second optical axis angle θ2, the _third optical axis angle θ3, and the first projection The angle Φ1, the _second projection angle Φ2, and the _third projection angle Φ3 can be obtained in advance as described in the _third embodiment. Therefore, by measuring the first frequency difference Δf ₁ , the second frequency difference Δf ₂ and the third frequency difference Δf ₃ , the distance change amount d can be calculated from the above equation (19).

(5-3) <Regarding the processing unit>
Next, the arithmetic processing device 41 according to the fourth embodiment will be described below with reference to FIG. Based on the above equations (10) and (18), the arithmetic processing unit 41 calculates the velocity V _X , _VY are measured, respectively, and the moving direction and speed V of the steel plate P can be measured from the speeds _VX and _VY , which are vector components. In addition to this, the arithmetic processing unit 41 performs a series of processes for measuring the movement direction and speed V of the steel plate P for the distance change amount d from the reference position of the steel plate P based on the above equation (19). can be measured simultaneously in FIG. 14 is a block diagram showing the circuit configuration of this arithmetic processing unit 41. As shown in FIG.

As shown in FIG. 14, an arithmetic processing unit 41 differs from the third embodiment in that a calculation unit 42 is provided with a distance/speed calculation unit 43 . Since other configurations are the same as those of the third embodiment, the distance/velocity calculator 43 will be focused on in the following description, and descriptions of the same configurations as those of the third embodiment will be omitted. In this case, the distance speed calculator 43 includes a first speed calculator 38a, a second speed calculator 38b, a composite speed calculator 38c, and a distance change amount calculator 43a.

The first speed calculator 38a calculates the first frequency difference Δf ₁ , the second frequency difference Δf ₂ , the third frequency difference Δf ₃ , the first optical axis angle θ ₁ , as in the third embodiment described above. , the second optical axis angle θ ₂ , the third optical axis angle θ ₃ , the first projection angle Φ ₁ , the second projection angle Φ ₂ , the third projection angle Φ ₃ , the constant k, and the wavelength λ of the laser light, the above Arithmetic processing is performed based on the equation (10) to calculate the velocity VX in the first movement direction _X.

The second speed calculator 38b calculates the first frequency difference Δf ₁ , the second frequency difference Δf ₂ , the third frequency difference Δf ₃ , the first optical axis angle θ ₁ , the second optical axis angle θ ₂ , the third Using the optical axis angle θ ₃ , the first projection angle Φ ₁ , the second projection angle Φ ₂ , the third projection angle Φ ₃ , the constant k, and the wavelength λ of the laser light, arithmetic processing is performed based on the above equation (18). and the velocity VY in the second moving direction _Y is calculated.

The composite speed calculator 38c obtains a composite vector from the speed VX calculated by the first speed calculator _38a and the speed _VY calculated by the second speed calculator 38b. That is, the combined speed calculator 38c calculates the square root of the sum of the squares of the speed VX in the first moving direction _X and the speed VY in the second moving direction _Y (√{( _VX ) ² +( _VY ) ² }) is calculated, the velocity V of the steel plate P is obtained, arctan (Vy/Vx) is calculated, and the direction shifted by arctan (Vy/Vx) from the reference direction (moving direction X here) is determined as the movement of the steel plate P Seek as a direction.

In addition, the distance change amount calculator 43a calculates the first frequency difference Δf ₁ , the second frequency difference Δf ₂ , the third frequency difference Δf ₃ , the first optical axis angle θ ₁ , the second optical axis angle Using θ ₂ , third optical axis angle θ ₃ , first projection angle Φ ₁ , second projection angle Φ ₂ , third projection angle Φ ₃ , constant k, and laser light wavelength λ, the above equation (19) is expressed as Arithmetic processing is performed based on this to calculate the distance change amount d. As described above, in the speed measuring device according to the fourth embodiment, the moving direction and the speed V of the steel plate P can be measured by the combined speed calculation unit 38c, and the distance change amount calculation unit 43a can calculate the distance from the reference position of the steel plate P. can also be measured simultaneously in a series of processes.

Since this distance change amount d indicates a relative position with respect to the reference position, when obtaining the distance from the velocity measuring device 52, it is possible to use the value of the distance to the reference position that has been measured in advance. , can be calculated.

Note that, in the fourth embodiment, similarly to the above-described first embodiment, frequency differences such as the first frequency difference Δf ₁ , the second frequency difference Δf ₂ and the third frequency difference Δf ₃ are calculated. When doing so, it is not necessary to use the first beat frequency, the second beat frequency and the third beat frequency detected when the steel plate P is relatively stationary at the reference position. For example, using the first beat frequency, the second beat frequency, and the third beat frequency detected when the steel plate P is moving at the reference speed at the reference position, the steel plate P is moving at a predetermined position at a speed other than the reference speed. A frequency difference may be calculated from the difference between the first beat frequency, the second beat frequency, and the third beat frequency detected at that time.

(6) <Other embodiments>
In the third and fourth embodiments described above, one laser oscillator 2 may be used to generate the first measurement light, the second measurement light, and the third measurement light. A first laser oscillator for generating light and a second laser oscillator for generating second measuring light separately provided, and a third measuring light separately for generating a third measuring light. A third laser oscillator may be provided to generate.

Further, in the third embodiment and the fourth embodiment described above, the velocity VX in the first moving direction _X and the velocity VY in the second moving direction _Y are combined to determine the direction of the combined vector, From the direction of this combined vector, the moving direction in which the steel plate P moves is measured, the square root of the sum of squares of the velocities V _X and V _Y is obtained, and the solution of the square root of the sum of squares is the speed of the steel plate P in the moving direction. As V, the speed measuring devices 51 and 52 for measuring the moving direction and speed V of the steel plate P have been described, but the present invention is not limited to this. For example, based on the velocities _VX and _VY , only one of the movement direction and the velocity V of the steel plate P may be measured. Further, the speed VX in the first moving direction _X and the speed VY in the second moving direction _Y are simply measured without finally calculating the moving direction of the steel plate P and the speed V in the moving direction. It may be a speed measuring device only.

Reference Signs List 1, 31, 51, 52 speed measuring device 2 laser oscillator 5a, 25a first measuring head 5b, 25b second measuring head 5c third measuring head 7a first photodetector 7b second photodetector 7c third photodetector Reference Signs List 11, 32, 33, 41 arithmetic processing unit 18 distance calculation unit 17a first frequency analysis unit (frequency analysis unit)
17b second frequency analysis unit (frequency analysis unit)
17c Third frequency analysis unit (frequency analysis unit)
19a first frequency difference calculator (frequency difference calculator)
19b Second frequency difference calculator (frequency difference calculator)
19c Third frequency difference calculator (frequency difference calculator)
21, 43 distance speed calculator 23, 43a distance change amount calculator 24 speed calculator 38a first speed calculator (speed calculator)
38b second velocity calculator (velocity calculator)
P steel plate (object to be measured)
S measurement surface (surface of object to be measured)

Claims (12)

In a velocity measurement method for measuring the relative velocity of an object to be measured,
a laser oscillation step in which a laser oscillation unit oscillates laser light modulated at a predetermined frequency modulation speed with respect to time;
a branching step of dividing the laser light into a reference light and a measurement light;
a first light receiving step of using a first measuring head to irradiate a part of the measurement light onto the object to be measured and receive the reflected light reflected by the surface of the object to be measured;
a second light receiving step of using a second measurement head to irradiate a part of the measurement light onto the object to be measured and receive the light reflected by the surface of the object to be measured;
A frequency for detecting a first beat frequency based on the reflected light received by the first measuring head and the reference light, and a frequency for detecting a second beat frequency based on the reflected light received by the second measuring head and the reference light an analysis step;
The first beat frequency detected when the object to be measured is relatively stationary at a reference position or is moving at a reference speed, and the object to be measured is relatively moving at a speed other than the reference speed. calculating a first frequency difference that is a frequency difference from the first beat frequency detected when the
The second beat frequency detected when the object to be measured is relatively stationary at the reference position or is moving at the reference speed, and the object to be measured is relatively at a speed other than the reference speed. a frequency difference calculating step of calculating a second frequency difference, which is a frequency difference from the second beat frequency detected while moving;
a speed calculation step;
has
The speed calculation step includes:
the wavelength of the laser light;
A first optical axis formed by a direction perpendicular to the moving direction and the optical axis of the first measuring head on a plane formed by the relative moving direction of the object to be measured and the optical axis of the first measuring head angle and
A second optical axis formed by a direction perpendicular to the moving direction and the optical axis of the second measuring head on a plane formed by the relative moving direction of the object to be measured and the optical axis of the second measuring head angle and
the first frequency difference;
the second frequency difference;
A velocity measuring method for measuring the relative velocity of the object to be measured with respect to the first measuring head and the second measuring head based on: having a distance change amount calculation step,
The distance change amount calculation step includes:
the wavelength of the laser light;
the frequency modulation rate;
the first optical axis angle;
the second optical axis angle;
the first frequency difference;
the second frequency difference;
2. The speed measuring method according to claim 1, wherein the distance from said reference position to said object to be measured is measured based on. having a distance change amount calculation step,
The distance change amount calculation step includes:
the wavelength of the laser light;
A frequency difference _Δf11 of the reflected light detected at each position when the object to be measured is changed by a predetermined distance change amount, and the distance change amount d of the object to be measured when the position is changed. and a constant k obtained by the formula k=Δf ₁₁ /d showing the relationship between
the first optical axis angle;
the second optical axis angle;
the first frequency difference;
the second frequency difference;
2. The speed measuring method according to claim 1, wherein the distance from said reference position to said object to be measured is measured based on. In a velocity measurement method for measuring the relative velocity of an object to be measured,
a laser oscillation step in which a laser oscillation unit oscillates laser light modulated at a predetermined frequency modulation speed with respect to time;
a branching step of dividing the laser light into a reference light and a measurement light;
a first light receiving step of using a first measuring head to irradiate a part of the measurement light onto the object to be measured and receive the reflected light reflected by the surface of the object to be measured;
a second light receiving step of using a second measurement head to irradiate a part of the measurement light onto the object to be measured and receive the light reflected by the surface of the object to be measured;
a third light receiving step of using a third measuring head to irradiate a part of the measurement light onto the object to be measured and receive the light reflected by the surface of the object to be measured;
detecting a first beat frequency based on the reflected light received by the first measuring head and the reference light, detecting a second beat frequency based on the reflected light received by the second measuring head and the reference light, a frequency analysis step of detecting a third beat frequency based on the reflected light received by the third measuring head and the reference light;
The first beat frequency detected when the object to be measured is relatively stationary at a reference position or is moving at a reference speed, and the object to be measured is relatively moving at a speed other than the reference speed. calculating a first frequency difference that is a frequency difference from the first beat frequency detected when the
The second beat frequency detected when the object to be measured is relatively stationary at the reference position or is moving at the reference speed, and the object to be measured is relatively at a speed other than the reference speed. calculating a second frequency difference that is a frequency difference from the second beat frequency detected while moving;
The third beat frequency detected when the object to be measured is relatively stationary at the reference position or is moving at the reference speed, and the object to be measured is relatively at a speed other than the reference speed. a frequency difference calculating step of calculating a third frequency difference, which is a frequency difference from the third beat frequency detected while moving;
a speed calculation step;
has
In the speed calculation step,
the wavelength of the laser light;
a first optical axis angle formed by the surface normal of the surface of the object to be measured and the optical axis of the first measurement head;
a second optical axis angle formed by the surface normal and the optical axis of the second measuring head;
a third optical axis angle formed by the surface normal and the optical axis of the third measuring head;
A first projection formed on the surface of the object to be measured by a projection of the optical axis of the first measuring head onto the surface of the object to be measured and a reference line extending in a plane direction along the surface of the object to be measured. angle and
a second projection angle formed on the surface of the object to be measured by the projection of the optical axis of the second measuring head onto the surface of the object to be measured and the reference line;
a third projection angle formed on the surface of the object to be measured by the projection of the optical axis of the third measuring head onto the surface of the object to be measured and the reference line;
the first frequency difference;
the second frequency difference;
the third frequency difference;
a constant k indicating a relationship between a change in the distance of the object to be measured from the first measurement head, the second measurement head, and the third measurement head and a change in the frequency of the laser light;
based on the first measuring head, the second measuring head, and the third A speed measuring method for measuring the relative speed of the object to be measured with respect to the measuring head. having a distance change amount calculation step,
The distance change amount calculation step includes:
the wavelength of the laser light;
the first optical axis angle;
the second optical axis angle;
the third optical axis angle;
the first projection angle;
the second projection angle;
the third projection angle;
the first frequency difference;
the second frequency difference;
the third frequency difference;
the constant k;
5. The speed measuring method according to claim 4, wherein the distance from said reference position to said object to be measured is measured based on the above. The velocity calculating step combines the velocity in the first moving direction and the velocity in the second moving direction to determine the direction of a combined vector, and from the direction of the combined vector, the moving direction in which the object to be measured moves. 6. The velocity measurement method according to claim 4 or 5, wherein In the speed calculation step, the square root of the sum of squares of the speed in the first moving direction and the speed in the second moving direction is obtained, and the solution of the square root of the sum of squares is obtained in the moving direction in which the object to be measured moves. The speed measurement method according to any one of claims 4 to 6, wherein the speed at In a speed measuring device that measures the relative speed of an object to be measured,
a laser oscillator that oscillates laser light modulated at a predetermined frequency modulation rate with respect to time;
a branching device that divides the laser beam into a reference beam and a measurement beam;
a first measuring head that irradiates the object to be measured with part of the measurement light and receives the reflected light reflected by the surface of the object to be measured;
a second measuring head that irradiates the object to be measured with part of the measurement light and receives the reflected light reflected by the surface of the object to be measured;
A frequency for detecting a first beat frequency based on the reflected light received by the first measuring head and the reference light, and a frequency for detecting a second beat frequency based on the reflected light received by the second measuring head and the reference light an analysis unit;
The first beat frequency detected when the object to be measured is relatively stationary at a reference position or is moving at a reference speed, and the object to be measured is relatively moving at a speed other than the reference speed. A first frequency difference is calculated, which is a frequency difference from the first beat frequency detected when the object to be measured is relatively stationary at the reference position, or is moving at the reference speed. and the second beat frequency detected when the object to be measured is relatively moving at a speed other than the reference speed. a frequency difference calculator for
a speed calculator;
has
The speed calculation unit
the wavelength of the laser light;
A first optical axis formed by a direction perpendicular to the moving direction and the optical axis of the first measuring head on a plane formed by the relative moving direction of the object to be measured and the optical axis of the first measuring head angle and
A second optical axis formed by a direction perpendicular to the moving direction and the optical axis of the second measuring head on a plane formed by the relative moving direction of the object to be measured and the optical axis of the second measuring head angle and
the first frequency difference;
the second frequency difference;
A speed measuring device for measuring the relative speed of the object to be measured with respect to the first measuring head and the second measuring head based on: having a distance change amount calculation unit,
The distance change amount calculation unit
the wavelength of the laser light;
the frequency modulation rate;
the first optical axis angle;
the second optical axis angle;
the first frequency difference;
the second frequency difference;
9. The speed measuring device according to claim 8, wherein the distance from the reference position to the object to be measured is measured based on. having a distance change amount calculation unit,
The distance change amount calculation unit
the wavelength of the laser light;
A frequency difference _Δf11 of the reflected light detected at each position when the object to be measured is changed by a predetermined distance change amount, and the distance change amount d of the object to be measured when the position is changed. and a constant k obtained by the formula k=Δf ₁₁ /d showing the relationship between
the first optical axis angle;
the second optical axis angle;
the first frequency difference;
the second frequency difference;
9. The speed measuring device according to claim 8, wherein the distance from the reference position to the object to be measured is measured based on. In a speed measuring device that measures the relative speed of an object to be measured,
a laser oscillator that oscillates laser light modulated at a predetermined frequency modulation rate with respect to time;
a branching device that divides the laser beam into a reference beam and a measurement beam;
a first measuring head that irradiates the object to be measured with part of the measurement light and receives the reflected light reflected by the surface of the object to be measured;
a second measuring head that irradiates the object to be measured with part of the measurement light and receives the reflected light reflected by the surface of the object to be measured;
a third measuring head that irradiates the object to be measured with part of the measurement light and receives the reflected light reflected by the surface of the object to be measured;
detecting a first beat frequency based on the reflected light received by the first measuring head and the reference light, detecting a second beat frequency based on the reflected light received by the second measuring head and the reference light, a frequency analysis unit that detects a third beat frequency based on the reflected light received by the third measurement head and the reference light;
The first beat frequency detected when the object to be measured is relatively stationary at a reference position or is moving at a reference speed, and the object to be measured is relatively moving at a speed other than the reference speed. calculating a first frequency difference that is a frequency difference from the first beat frequency detected when the
The second beat frequency detected when the object to be measured is relatively stationary at the reference position or is moving at the reference speed, and the object to be measured is relatively at a speed other than the reference speed. calculating a second frequency difference that is a frequency difference from the second beat frequency detected while moving;
The third beat frequency detected when the object to be measured is relatively stationary at the reference position or is moving at the reference speed, and the object to be measured is relatively at a speed other than the reference speed. a frequency difference calculator that calculates a third frequency difference that is a frequency difference from the third beat frequency detected while moving;
a speed calculation step;
has
The speed calculation unit
the wavelength of the laser light;
a first optical axis angle formed by the surface normal of the surface of the object to be measured and the optical axis of the first measurement head;
a second optical axis angle formed by the surface normal and the optical axis of the second measuring head;
a third optical axis angle formed by the surface normal and the optical axis of the third measuring head;
A first projection formed on the surface of the object to be measured by a projection of the optical axis of the first measuring head onto the surface of the object to be measured and a reference line extending in a plane direction along the surface of the object to be measured. angle and
a second projection angle formed on the surface of the object to be measured by the projection of the optical axis of the second measuring head onto the surface of the object to be measured and the reference line;
a third projection angle formed on the surface of the object to be measured by the projection of the optical axis of the third measuring head onto the surface of the object to be measured and the reference line;
the first frequency difference;
the second frequency difference;
the third frequency difference;
a constant k indicating a relationship between a change in the distance of the object to be measured from the first measurement head, the second measurement head, and the third measurement head and a change in the frequency of the laser light;
based on the first measuring head, the second measuring head, and the third A speed measuring device for measuring the relative speed of the object to be measured with respect to the measuring head. having a distance change amount calculation unit,
The distance change amount calculation unit
the wavelength of the laser light;
the first optical axis angle;
the second optical axis angle;
the third optical axis angle;
the first projection angle;
the second projection angle;
the third projection angle;
the first frequency difference;
the second frequency difference;
the third frequency difference;
the constant k;
12. The speed measuring device according to claim 11, wherein the distance from the reference position to the object to be measured is measured based on.

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