JPH0816609B2 - Angle measuring device - Google Patents

Description

The present invention relates to an angle measuring device, and more particularly to an angle measuring device suitable for use in applications such as measuring a joint angle of a propeller shaft of a vehicle.

[Prior Art] A drive system of a vehicle includes an engine, a propeller shaft, a differential gear (hereinafter referred to as a differential), and the like, each having a rotation shaft. These shafts are connected to each other by Hookes joints and have a defined joint angle at the connection. It is well known that this joint angle is related to the noise generated from the drive system. Therefore, it is important to measure the joint angle. A device that uses the Doppler effect of laser light is known as a device that accurately measures an angle, but this method cannot measure the absolute value of the angle, and only measures the relative displacement angle of how much the angle has changed. It was not possible to measure the joint angle because it was not possible. For this reason, the joint angle is currently measured by using a level, a protractor, etc., which has the drawbacks of poor accuracy and reproducibility and a large number of measurement steps. Therefore, a method for easily and accurately measuring the joint angle has been desired.

The present invention has been made in view of the above demands, and an object of the present invention is to provide an angle measuring device which can measure a joint angle and the like with high accuracy and easily and has a compact structure.

[Means for Solving the Problems] The configuration of the present invention will be described with reference to FIGS. 1 and 3. The angle measuring device is provided on one of a pair of base surfaces 1 and 2 that form an angle with each other. It comprises a light emitter 4 which emits a light ray 7 parallel to it along the surface 2 and a light receiver 5 which is provided on the other base surface 1 and which makes said light ray incident. The light emitter 4 is equipped with a light emitting means for emitting a circularly polarized light beam. Further, the light receiver 5 includes a beam splitter plate 11 for passing a part 7a of the light beam 7 incident on the plate surface and reflecting a remaining part 7b in a direction different from the incident direction, and the beam splitter plate 11 A reflection plate 12 provided in the rear in parallel with this to totally reflect the light beam 7a after passing through the beam splitter plate 11, the detection surface is made flat, and the light beam 7b reflected by the beam splitter plate 11 is made incident. The first coordinate detecting means 13 for outputting a coordinate signal according to the two-dimensional coordinates of the incident point and the detecting surface are formed in a plane, and are arranged on the same plane as the detecting surface of the first coordinate detecting means 13, Second coordinate detecting means 14 for making the light rays reflected by the reflecting plate 12 incident and outputting coordinate signals corresponding to the two-dimensional coordinates of the incident point, and outputs of the first and second coordinate detecting means 13, 14 Head amplifier circuit 15 for processing coordinate signals Is output from the head amplifier circuit 15 the first and second coordinate detecting means
The calculation display means 6 for calculating and displaying the angle formed by the two base surfaces from the coordinates of the incident points obtained in 13 and 14, respectively.

[Effect] According to the angle measuring device having the above-described configuration, the first and the first light-receiving surfaces, in which the parallel reflected lights from the light-emitting device 4 and the light-receiving device 5 are juxtaposed on each of the measured base surfaces, form a common plane. Since it is received by the two coordinate detecting means, the angle formed by both base surfaces can be measured with high accuracy and easily. Moreover, the structure becomes compact.

In the device of the present invention, since the circularly polarized light is emitted from the light emitter 4, even if the installation position of the light emitter 4 changes around the optical axis, an accurate measurement can be performed without causing an error. .

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an embodiment in which the present invention is applied to measurement of a joint angle of a propeller shaft of an automobile. Reference numerals 1 and 2 are propeller shafts driven by an engine not shown in the drawing, which are divided into two by a hooks joint 3. Propeller shafts 1 and 2 do not have their central axes on a straight line, and are generally coupled with a joint angle θ other than 10 degrees. Reference numeral 4 denotes a light emitter installed on the propeller shaft 2, and emits a light beam 7 parallel to the central axis of the propeller shaft 2 which is one of the base surfaces. Reference numeral 5 is a light receiver installed on the propeller shaft 1 which is the other base surface, and has a reference axis 5a, and the central axis of the propeller shaft 1 and the reference axis 5a are parallel to each other. The light receiver 5 is connected to an angle calculation display 6 which is an external calculation display means, and the calculation display 6 inputs the output signal of the light receiver 5 and displays the joint angle θ by calculation.

FIG. 2 shows a perspective view of the light emitter 4. The light emitter 4 is a substantially rectangular parallelepiped case 45 that is polished and finished so that each surface becomes a right angle
The case 45 has a laser diode 41, a collimator lens 42, and a linear polarizer 43 arranged along the major axis thereof. The laser diode 41 is driven to emit light by the drive circuit 44.

The laser light emitted from the laser diode 41 generally has a linearly polarized light, and since the light has a divergence angle, it is collimated by the collimator lens 42. The light emitted from the collimator lens 42 does not change its polarization state and becomes linearly polarized light.
The light beam that has passed through the collimator lens 42 passes through the linear polarizer 43. The linear polarizer 43 is a quarter-wave plate and its optical axis forms an angle of 45 degrees with the plane of polarization of the incident linearly polarized light. The light passing through the linear polarizer 43 becomes circularly polarized light having no plane of polarization.

The case 45 has a V groove 4a on the bottom surface and a side surface,
4b is formed, and is adsorbed and fixed to the propeller shaft 2 at the V-grooves 4a and 4b by a built-in magnet. Then
As shown in the figure, when fixed to the propeller shaft 2 with the V groove 4a, the light beam 7 emitted from the light emitter 4 becomes parallel to the axis of the propeller shaft 2. This ray 7 is the propeller shaft 1
The light is incident on the light receiver 5 provided in (FIG. 1).

FIG. 3 is a cross-sectional view showing the structure of the light receiver 5 shown in FIG. 1, which is a rectangular parallelepiped having a V groove like the light emitter 4 shown in FIG. I am doing it.
In FIG. 3, 10 is a filter that passes only light having the same wavelength as the light ray 7 and cuts out disturbance light, and 11 is a beam splitter plate, which reflects a part of the light ray 7 and outputs the reflected light 7b and the light ray 7 And transmits a transmitted light 7a. 12
Reflects the transmitted light 7a by a reflecting mirror. Reference numerals 13 and 14 generate coordinate signals corresponding to the coordinates of the two-dimensional incident point of the light incident on the incident position detector, and a position sensing detector (for example, S1300 manufactured by Hamamatsu Photonics KK) can be used. Incident position detectors 13 and 14 are provided facing the beam splitter 11 and the reflecting mirror 12, respectively, as shown in the figure, and determine the incident point positions of the reflected light 7b and the transmitted light 7a of the beam splitter 11, respectively. As shown in FIG. 3, the incident position detectors 13 and 14 have a flat detection surface and are arranged so that the two detection surfaces are located on the same plane. Fifteen
Is a printed circuit board that constitutes a head amplifier circuit that processes the coordinate signals output from the incident position detectors 13 and 14.
The printed circuit board 15 is provided on the back side of the incident position detectors 13 and 14 so as to closely face them.

FIG. 4 shows the configuration of the head amplifier circuit 15 shown in FIG. 3. The incident position detectors 13 and 14 are provided with the same processing circuits 15a and 15b independently of each other. Processing circuit
In 15a, 151a, 152a, 153a and 154a are known current-voltage conversion circuits composed of resistors and operational amplifiers, and 155a and 156a are subtraction circuits composed of resistors and operational amplifiers. This processing circuit
15a, the respective signals 131a, 131b forming the coordinate signal 131,
131c and 131d are converted into voltage signals and output.

Similarly, the coordinate signal 141 of the incident position detector 14 is constructed 141
The processing circuits 15b having the same circuit configuration as the processing circuit 15a convert a, 141b, 141c, and 141d into voltage signals and output them.

FIG. 5 shows the configuration of the operation display unit 6 shown in FIG. 1. Reference numerals 61 and 62 denote amplifiers A and B having the same circuit configuration. The processing circuit 15 has four known non-inverting amplifier circuits and is an output coordinate signal of the light receiving unit 5.
The output signals of a and 15b (Fig. 4) are amplified respectively. A switch 63 determines the sampling timing of the output coordinate signal of the detection unit 5. Reference numeral 64 is a sample-and-hold circuit, which is well known in the art, but the configuration thereof is omitted. The timing of sampling is determined by the signal of the switch 63, and the output signal of the sample hold circuit 64 is the coordinates of the incident position detectors 13 and 14 at the time when the switch 63 is turned on. 65 is a multiplexer, for example, a well-known multiplexer (MX-808 manufactured by Digital Co., Ltd.) is used. Multiplexer 6
Reference numeral 5 selects and outputs one of the eight output signals of the sample hold circuit. 66 is a known A / D conversion circuit,
For example, a 12-bit A / D converter (ADC80-
AG12) is used. Reference numerals 67, 68, and 69 respectively constitute a microcomputer. 67 is a CPU, 68 is a ROM, 69 is a RAM, and they are connected by a bus line 611. In this example, C
PU67 uses an 8-bit CPU (H6803 manufactured by Hitachi, Ltd.). Also, the signal of the switch 63 is input as an interrupt signal. A program for arithmetic processing is stored in advance in the ROM 68 as machine code. RAM69 is ROM68
It is for the work area to execute the programs stored in. A display device 610 displays the calculated joint angle θ.

Next, the program stored in the ROM 68 shown in FIG. 5 will be described with reference to the flow chart shown in FIG.

The program is composed of two routines, FIG. 6 (1) is an initial routine, and FIG. 6 (2) is an interrupt routine. The initial routine is a routine that is started when the power is turned on. First, in step S1, the memory is initialized. Next, in step S2, the display is cleared, and in step S3 interrupts are enabled. After that, step S3 is repeated to wait for an interrupt. FIG. 6 (2) shows an interrupt routine, which is started when the above-mentioned initial routine executes step S3 and the switch 63 is turned on.

First, in step i1, its own interrupt is disabled, and then in step i2, the channel of the multiplexer 65 is set to CH1. Next, in step i3, the analog data of channel CH1 is read as A / D data and stored in a specific address in RAM 69. Next, at step i4, the multiplexer 65 is set to the next channel CH2. In step i5, it is determined whether the data of channel 8 has been read. If channel 8 has not ended, the result is NO, and the process returns to step i3. When this loop is rotated 8 times, the data of 8 channels (data of CH1 to CH8) are read and stored in the memory, and the process proceeds to step i6. Channels CH1 to CH4 in step i6
The incident coordinates P of the incident position detector 14 using the data of
Calculate (X ₁ , Y ₁ ). Further, in step i7, the coordinates Q (X ₂ , Y ₂ ) incident on the incident position detector 13 are calculated using the data of the channels CH5 to CH8.

Coordinates P and Q are calculated as follows. CH1 ~ CH4
X _1A of data, respectively, and _{X 1B, Y 1A, Y 1B} , respectively X _2A data CH5 to CH8, X _2B, Y _2A, when the Y _2B obtained by the following equation.

Here, L is the maximum value that the coordinates of the incident position detectors 13 and 14 can take.

Furthermore, in step i8, the joint angle θ is calculated from the P and Q coordinates obtained in steps i6 and i7. The calculation formula is calculated by the following formula.

Here, d is defined as the difference between the optical path length of the optical path from the light emitter 4 to the incident position detector 13 and the optical path length of the optical path from the light emitter 4 to the incident position detector 14, and in the above angle measuring device, This is the distance between the beam splitter plate 11 and the reflecting plate 12 because the detection surfaces of the position detectors 13 and 14 are arranged on the same plane, and the distance between the coordinate origins of the incident position detectors 13 and 14.

When measuring the joint angle θ with the angle measuring device having the above-mentioned configuration, the light emitter 4 is fixed to the propeller shaft 2 by suction. At this time, the light beam from the light emitter 4 is emitted from the propeller shaft 2.
It is parallel to the central axis of. The light receiver 5 is fixed by suction onto the other propeller shaft 1 through the hook joint 3.

At this time, the light receiver 5 is appropriately positioned in the axial direction of the propeller shaft 1 so that the light beam incident on the light receiver 5 falls within the effective coordinates of the incident position detectors 13 and 14 incorporated therein. Although not described in detail in the present embodiment, it is determined whether the output of the multiplexer is below a certain level, and if the output of the multiplexer is below a certain level, light is not incident if it is below a certain level. I can judge.

When the switch 63 is pressed, the display unit 610 displays the joint angle θ.

In the angle measuring device, the transmitted light 7a is reflected by the reflection plate 12.
Since the light is reflected in the same direction as 7b and made incident on the position detector 14, the light receiver 5 can be made short in the direction in which the light beam 7 is made incident, and the position detectors 13 and 14 are arranged adjacent to each other. Therefore, the light receiver can be made compact. Also,
Since the detection surfaces of the position detectors 13 and 14 are arranged on the same plane, the light reflected by the beam splitter plate 11 is the position detector 13
The angle of incidence to the position detector and the light reflected by the reflector 12
The angle of incidence on 14 becomes equal. As a result, the correspondence between the two-dimensional coordinates of the incident point and the coordinate signal is aligned between the position detectors 13 and 14, and the angle measurement error can be suppressed.

By the way, when a linearly polarized light beam is used for measurement, an error may occur when the installation position of the light emitter 4 changes around the optical axis due to interference or the like at the beam splitter plate 11. On the other hand, in the present invention, since the circularly polarized light beam is used for measurement, the polarization plane of the light beam is rotated and the light intensity and the like in the beam splitter plate 11 are constant, and the installation position of the light emitter 4 is fixed. There is no error caused by this, and accurate measurement is possible.

[Brief description of drawings]

FIG. 1 is a device configuration diagram showing an example in which an angle measuring device is provided on a propeller shaft of a vehicle, FIG. 2 is a perspective view of a light emitter, and FIG.
FIG. 4 is a sectional view of a light receiver, FIG. 4 is a circuit diagram of a head amplifier circuit, FIG. 5 is a circuit configuration diagram of a calculation display device, and FIG. 6 is a program flow chart. 1, 2 ...... Propeller shaft (base surface) 4 ...... Light emitter 41 ...... Laser diode 42 ...... Collimator lens 43 ...... Linear polarizer 5 ...... Light receiver 11 ...... Beam splitter plate 12 ...... Reflector plate 13 ...... ... Incident position detector (first coordinate detecting means) 14 ... Incident position detector (second coordinate detecting means) 15 ... Head amplifier circuit 6 ... Calculation display

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Miyawaki, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor, Kenichi Yamamoto, 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Go Kaku 1 Toyota-cho, Toyota City, Aichi Prefecture, Toyota Toyota Motor Corporation (56) References Japanese Patent Publication No. 2-4843 (JP, B2) Japanese Patent Publication No. 56-25601 (JP, B2) Japanese Patent Publication 1-39042 (JP, B2) Jikkou 57-26169 (JP, Y2)

Claims (3)

[Claims] 1. A light-emitting device provided on one of a pair of base surfaces forming an angle with each other and emitting a light beam parallel to the base surface, and a light-receiving device provided on the other of the base surfaces for allowing the light beam to enter. And a light emitting means for emitting a circularly polarized light beam, and the light receiving device allows a part of the light beam incident on the plate surface to pass and a remaining part of the light beam to enter. A beam splitter plate that reflects in a direction different from the direction, a reflector plate that is provided in parallel with the beam splitter plate behind the beam splitter plate and totally reflects the light rays that have passed through the beam splitter plate, and the detection surface is a flat surface. First coordinate detecting means for making the light beam reflected by the splitter plate incident and outputting a coordinate signal according to the two-dimensional coordinates of the incident point, and the detecting surface is made flat, and the detecting surface of the first coordinate detecting means Same as Second coordinate detecting means, which are arranged on a plane and which make the light rays reflected by the reflecting plate incident and output a coordinate signal according to the two-dimensional coordinates of the incident point, and the first and second coordinate detecting means. From the head amplifier circuit that processes the coordinate signal output by the head amplifier circuit and the incident point coordinates output from the head amplifier circuit and obtained by the first and second coordinate detecting means, respectively, the angle formed by the two base surfaces is calculated. An angle measuring device comprising: a calculation display unit for displaying. 2. The head amplifier circuit is composed of a printed circuit board, and the printed circuit board is arranged on the back side of the first and second coordinate detecting means so as to closely face the first and second coordinate detecting means. The angle measuring device according to claim 1, which is provided. 3. A laser diode for emitting linearly polarized laser light, the light emitting means being provided in front of the laser diode, and having an optical axis with respect to a plane of polarization of the laser light.
The angle measuring device according to claim 1, wherein the angle measuring device comprises a linear polarizer composed of a quarter-wave plate set at 45 degrees.