JP3427187B2 - Distance measuring apparatus and measuring method using modulated light - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring means, and more particularly to a transponder type distance measuring means using modulated diffused light. INDUSTRIAL APPLICABILITY The present invention can be used for position recognition of an object that moves within a limited range, such as an agricultural vehicle in a field or an automatic guided vehicle in a factory, and measures the distance between two vehicles. It can also be used for controlling systems.

[0002]

2. Description of the Related Art Conventionally, as a method of contactlessly measuring a distance between a fixed point and a moving body or a distance between two moving bodies by an electromagnetic wave, (1) a measuring method by a tracking type optical wave rangefinder, (2) There are known a measurement method using a laser scanner, (3) a measurement method using a transponder using a light beam, and (4) a measurement method using a transponder using radio waves.
The transponder generally means a transmission / reception system capable of receiving an interrogation signal from an interrogator and automatically transmitting an appropriate response.

In the method (1), as shown in FIG. 9, the reflector 12 mounted on the moving body 122 from the optical distance measuring instrument 121.
3 is irradiated with the light beam 124, the reflected light 125 is received, and the round trip time of the light is detected from the modulation phase difference between the transmitted and received waves to measure the distance. The irradiation direction of the light beam 124 is the moving body 1.
Since it is necessary to track the reflector 123 that moves along with the movement of the mobile phone 22 and to change it vertically and horizontally,
The use of an automatic tracking device (not shown) to track the 2 is essential.

The method (2) uses a radar.
As shown in FIG. 10, a laser beam or a microwave 127 is emitted from the distance measuring device 126 to scan the moving body 1
The round trip time is measured by reflecting the light with the reflecting plate 128 of 22.
A device that irradiates a laser is often used at a short distance, and is called a laser scanner, a laser radar, or a lidar. In this case, a reflector 128 may be attached to the moving body 122 to be measured in order to specify the reflection position.

The distance measuring method using the light beam transponder of (3) is a method of transmitting the light beams 130 and 131 from the two distance measuring devices 129 and receiving them from each other. As shown in FIG. 11, this method is a method developed for arranging distance measuring devices 129 at fixed points and accurately measuring the distance between them.

In the method (4), as shown in FIG. 12, the radio wave 13 is transmitted between the distance measuring device 134 and the moving body 122 which are in a fixed position.
2, 133 are mutually transmitted and received to measure the distance.

[0007]

However, although the method of (1) above enables highly accurate measurement, the optical rangefinder 121
Since the light beam from the above must always illuminate the reflector 123 of the moving body, a complicated and expensive automatic tracking device is required, and there is a problem that the cost of the system increases. Further, in the method using the scanning method of (2) above,
Shake the light beam or the microwave beam 57 to the left or right,
Or, because it is necessary to rotate in all directions and scan,
Although there is an advantage that multiple objects can be measured, there is a problem in that the distance measurement accuracy is low. On the other hand, the optical beam transponder method of (3) above is a method developed for precisely measuring the distance between fixed points, and when it is used for a moving body, it requires two tracking devices and is not practical. There was a problem that it was low. On the other hand, in the radio wave transponder method of (4), when an omnidirectional radio wave is used, a tracking device is not particularly required and the cost is low. However, measurement error due to multipath of radio waves such as ground reflection becomes a problem. In addition, there is a problem in that the system must be configured under the regulation of the Radio Law, and there are many restrictions.

As described above, the conventionally known distance measuring methods have various peculiar problems as described above, and it is necessary to develop a highly accurate and low cost measuring method which solves these problems. Has been sought.

Therefore, the present invention has been made in view of the above problems in the prior art. For example, the position measurement of an object moving within a relatively narrow and limited range such as in a field or a factory, or 2 An object of the present invention is to solve the above-mentioned various problems in the distance measurement between the moving bodies of the table.

Therefore, an object of the present invention is to provide means for performing highly accurate distance measurement at low cost by a transponder system using diffused light.

INDUSTRIAL APPLICABILITY The present invention can be expected to be applied in a wide range of applications including a position recognition system for agricultural vehicles and factory guided vehicles, traveling control for unmanned vehicles, measurement and control system for relative positions of preceding vehicles and accompanying vehicles. Is.

[0012]

According to the present invention, the distance between a moving body moving within a limited range such as a field or a factory and a predetermined fixed point, or the distance between two moving bodies is accurately determined. The present invention provides a measuring method and device. For this reason, by installing an optical transceiver that is equipped with a plurality of light-emitting diodes that emit diffused light and that is capable of transmitting and receiving in almost all horizontal directions and that is composed of a plurality of or a single optical sensor on both measurement targets, Is an optical transponder type distance measuring device or method that enables distance measurement no matter how changes occur.

The present invention is an optical transponder type distance measuring device, which has a plurality of light emitting diodes arranged so as to radiate a first modulated light modulated at a first frequency over a predetermined angular range. And a light receiving unit arranged so as to be able to receive a second modulated light modulated at a second frequency over a predetermined angle range.

Further, the plurality of light emitting diodes are distance measuring devices arranged so as to be able to emit the first modulated light in the entire circumferential direction in the horizontal direction, and the light transmitting section is in a columnar shape. And a plurality of the light emitting diodes are arranged on the side surface of the light emitting diode holding member.

Further, the light receiving section is a distance measuring device having a plurality of light sensors, and the plurality of light sensors are arranged so as to be able to receive light from all circumferential directions in the horizontal direction, A distance measuring device in which the light receiving unit has a columnar optical sensor holding member, and the plurality of optical sensors are arranged on a side surface of the optical sensor holding member, wherein the light receiving unit is a reflection plate and the reflection plate. An optical sensor for receiving the reflected light reflected by the optical receiver, wherein the light receiving unit converges the second modulated light on the surface of the optical sensor that receives the reflected light by being reflected by the reflector. It is a formed distance measuring device.

Further, the present invention is an optical transponder type distance measuring device, wherein a plurality of light emitting diodes are arranged so that the first modulated light modulated at the first frequency can be horizontally emitted over a predetermined angular range. Optical transmission / reception provided with a first optical transmission section having an optical path and a first optical reception section arranged so as to be able to receive the second modulated light modulated at the second frequency over a predetermined angular range. And a second optical transmitter having a plurality of light emitting diodes arranged so that the second modulated light modulated at the second frequency can be horizontally radiated over a predetermined angular range, and at the first frequency A second optical transceiver including a second optical receiver arranged so as to be capable of receiving the modulated first modulated light over a predetermined angular range, and is a distance measuring device.

The present invention also provides a first measuring unit and a second measuring unit.
An optical transponder type distance measuring device having a measuring unit of:
A first electric signal generating means for generating an electric signal of a frequency, and a first modulated light connected to the first electric signal generating means and modulated by the electric signal of the first frequency in a first angular range. The second measurement unit has a first light transmitting means for horizontally radiating, and the second measuring unit receives the first modulated light, and second electric signal generating means for generating an electric signal of a second frequency. Second optical receiving means for demodulating into an electric signal, and a second beat for mixing the electric signal of the second frequency and the electric signal demodulated by the second optical receiving means to generate a second beat signal. Signal generating means, second adding means for adding an electric signal of a second frequency and the second beat signal to generate an added signal, and a second modulated by the added signal
A second light transmitting means for horizontally radiating the modulated light in the second angular range, wherein the first measuring unit further receives the second modulated light and demodulates it into an electric signal. 1
Optical receiving means, the electrical signal of the first frequency and the first signal
Mixing the electric signal demodulated by the optical receiving means of
First beat signal generating means for generating the beat signal of
From the electrical signal demodulated by the first optical receiving means,
A distance measuring device having demodulation means for generating a demodulated second beat signal and phase comparison means for detecting and outputting a phase difference between the first beat signal and the demodulated second beat signal. is there.

The present invention is also a method for measuring the position of a moving body, wherein the first measuring unit is arranged in a first fixed position, the second measuring unit is arranged in the moving body, and the third measuring unit is arranged.
Arranging the measuring unit in a second fixed position at a predetermined distance from the first measuring unit;
Measuring unit for generating a first high frequency signal of frequency f _{1 and} a second measuring unit for generating a second high frequency signal of frequency f ₂ ; and the first measuring unit for measuring the first high frequency signal. Generating and horizontally radiating a signal-modulated first modulated light, and the second measurement unit generating and horizontally radiating a second modulated light modulated by the second high-frequency signal. And the first measurement unit receives the second modulated light and generates a first low frequency beat signal at a frequency f ₁ -f ₂ , and the second measurement unit causes the first modulated signal to be generated. The light is received and the frequency of f ₁ -f ₂
Generating a second low frequency beat signal, wherein the second measuring unit outputs the second low frequency beat signal to the second
Radiating the modulated light on the modulated light, the step of receiving the second modulated light having the second low-frequency beat signal by the third measuring unit, and the first measuring unit by the first measuring unit. Transmitting the low-frequency beat signal of the first high-frequency signal to only the third measuring unit, and the first low-frequency beat signal including the first low-frequency beat signal.
Receiving the high frequency signal of the third measurement unit, the third measurement unit demodulates the first high frequency signal sent from the first measurement unit, and the second measurement Demodulating the second modulated light sent from the unit to generate a third low frequency beat signal of frequencies f ₁ -f ₂ based on these two demodulated signals; and the third measurement. A unit performing a phase comparison of the first, second and third low frequency beat signals,
A method for measuring the position of a moving body, comprising the step of obtaining the distance between the first and second measurement units and the distance between the second and third measurement units from the phase difference and obtaining the position of the second measurement unit. is there.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An optical transceiver according to the present invention and a distance measuring system using the same will be described below in detail with reference to the embodiments shown in the accompanying drawings. The following description is an example of the invention and is intended to illustrate the general principles of the invention. Therefore, the present invention is not limited to the configuration specifically described in this embodiment. In the following detailed description and description of the drawings, similar elements are represented by similar reference numbers.

The present invention relates to an optical transponder type distance measuring device for exchanging optical signals between two stations, and in particular, by transmitting modulated diffused light over a wide range, it is possible to transmit and receive light over a wide angle range. It makes it possible to do. Therefore, it is possible to measure the distance between two stations that move relative to each other without controlling the directions of the optical transmitter and the optical sensor.

Basic Principle of Distance Measuring System Using Optical Transponder Method FIG. 1 is a schematic diagram for explaining the basic principle of the distance measuring system using the optical transponder method according to the present invention. The ranging system 1 of FIG. 1 consists of two stations A and B, stations 2 and 3, which are respectively attached to the two points whose distances need to be measured. The measuring unit 4 and the measuring unit 5 arranged in the A station 2 and the B station 3 respectively have an oscillator A6 and an oscillator B7.
6 and an oscillator B7 generate high frequency signals of frequencies f ₁ and f ₂ , respectively, and an optical transmitter A8 and an optical transmitter B9 are provided.
Send to. The optical transmitter A8 and the optical transmitter B9 optically modulate these high frequency signals and emit them as modulated light 12 and modulated light 13 to the other station.

Here, the frequencies f ₁ and f ₂ are close to each other but have different values. It does not matter which is larger, but here it is assumed that f ₁ > f ₂ . Let these high-frequency electric signals (functions of time) be y ₁ and y ₂ , respectively, and y ₁ = sin (ω ₁ t-φ ₁ ) y ₂ = sin (ω ₂ t-φ ₂ ) (1). In principle, it is not necessary to consider the amplitude, so the amplitude is 1
And ω ₁ and ω ₂ are angular frequencies, and ω ₁ = 2πf ₁ ω ₂ = 2πf ₂ (2). Note that φ ₁ and φ ₂ represent phases. These are unknowns. The A station 2 and the B station 3 irradiate the opposite stations with the modulated lights 12 and 13 in which the electric signals of y ₁ and y ₂ are added as light modulation signals.

The modulated lights 12 and 13 are received by the optical receivers B11 and A10 of the B station 3 and A station 2 and demodulated into electric signals. Each of the demodulated electrical signals is y
₁ ', y ₂ ' Assuming that the distance between A and B stations is D and the speed of light is C, it takes D / C time for light to propagate between these two stations, so that y ₁ ′ and y ₂ ′ are expressed by the following equations.

Y ₁ '= sin {ω ₁ (tD / C) -φ ₁ } y ₂ ' = sin {ω ₂ (tD / C) -φ ₂ } (3) The amplitude is also set to 1.

At the B station 3, the received signal y ₁ 'and the B station 3
The signal y ₂ generated by the oscillator B7 of ₁ is mixed by the mixer 15. The mixer 15 is a general analog integrating circuit,
The product of the signals y ₁ 'and y ₂ is output as shown in the following equation.

[0026]   y₁’・ Y₂= sin {ω₁(t-D / C) -φ₁} ・ Sin (ω₂t-φ₂)     = − [Cos {(ω₁+ ω₂) t- (φ₁+ φ₂) -ω₁D / C}] / 2+ [cos {(ω₁-ω₂) t- (φ₁-φ₂) -ω ₁ D / C}] / 2                                                                 (4) This signal has a frequency f as can be seen from equation (4).₁+ F
_TwoHigh frequency signal and frequency f₁-F_TwoSum of low frequency signals
Becomes

If this is passed through the low pass filter 17, only the low frequency beat signal can be taken out. Y ₃
Then, y ₃ is expressed by the following equation.

Y ₃ = cos {(ω ₁ -ω ₂ ) t- (φ ₁ -φ ₂ ) -ω ₁ D / C} (5) Here, the change in amplitude is also ignored.

Similarly, at the station A 2, the signal y ₁ internally generated is generated.
And the received signal y ₂ 'are mixed to generate a beat signal y ₄ as shown in the following equation.

Y ₁ · y ₂ '= ・ sin (ω ₁ t-φ ₁ ) ・ sin {ω ₂ (tD / C) -φ ₂ } = − [cos {(ω ₁ + ω ₂ ) t- (φ ₁ + φ ₂ ) -ω ₂ D / C}] / 2+ [cos {(ω ₁ -ω ₂ ) t- (φ ₁ -φ ₂ )-ω ₂ D / C}] / 2 (6) Similar to the low pass filter 16, only the low frequency beat signal is extracted.

Letting this be y ₄ , y ₄ is expressed by the following equation.

Y ₄ = cos {(ω ₁ -ω ₂ ) t- (φ ₁ -φ ₂ ) -ω ₂ D / C} (7) Here also, the change in amplitude is ignored.

Next, the beat signal obtained at station B is sent to station A to compare the phases of the beat signals. Therefore, the low-frequency beat signal y ₃ generated by the B station is sent from the B station to the A station by light or radio waves 22. For example, the signal y ₃ is sent from the beat signal transmitter 19 of the station B to the beat signal receiver 18 of the station A by carrying it on the light or the radio wave 22. In addition, the beat signal y ₃ is modulated by the modulated light 13
It is also possible to carry the signal from the optical transmitter B9 and to transmit it.

The signal y ₃ is transmitted from the A station to the B station by the D / C
Therefore, by substituting t-D / C for t in the equation (5), the equation for the beat signal y ₃ 'received at the A station can be obtained as follows.

Y ₃ '= cos {(ω ₁ -ω ₂ ) (t D / C)-(φ ₁ -φ ₂ ) -ω ₁ D / C} = cos {(ω ₁ -ω ₂ ) t- (φ _1- φ ₂ ) -2ω ₁ D / C + ω ₂ D / C} (8) In order to compare the signal y ₃ 'of equation (8) with y _{4 of} (7) at the station A, the phase comparator 20 Using signal y ₃ 'and signal y
The phase difference of ₄ is obtained. If this phase difference is Δφ, Δφ = 2ω ₁ D / C (9) is obtained.

Phase difference Δ between the beat signals y ₄ and y ₃ '
From φ, it can be seen that the distance D between the A station and the B station is obtained as D = ΔφC / 2ω ₁ (10).

Thus, the detected phase difference Δφ and the distance
The relationship of D is φ in principle₁And φ ₂A, regardless of
Station frequency ω₁Depends only on. That is, in equation (9)
Unknown value φ₁And φ_{2 is}It has been erased. Therefore,
Signal y₃’And signal y_FourBy measuring the phase difference Δφ of
Therefore, the distance D between station A and station B can be accurately measured.
it can.

In order to continuously measure accurately the distance between two stations, at least one of which is moving, using the above-mentioned optical transponder system, the modulated lights 12, 13 and the light, the radio wave 22 are used.
There is a need for a transmitter / receiver and a signal processing system capable of stably performing transmission / reception and signal processing with a small electric power, and easily performing irregular optical movement between two stations to continuously perform optical transmission / reception.

FIG. 2 shows an example of an embodiment of the optical transceiver 37 according to the present invention. The optical transmitter / receiver 37 has a plurality of light emitting diodes 33, which are connected to a signal processing circuit (not shown) and are controlled respectively, on a side surface of a column 32 which is a light emitting diode holding member vertically held by the support column 31. Attach it so that it faces the irradiation direction. FIG. 2 shows an example in which radiation is arranged in the entire circumferential direction in the horizontal direction. The light emitting diode holding member is not limited to the column,
The cross section may be a polygon such as a regular hexagon or a regular octagon.

For example, as shown in FIG. 2, the light emitting directions of the plurality of light emitting diodes 33 are horizontal and omnidirectional (angle range is 3).
(60 degrees) makes it possible to emit the modulated light 12, 13 or 22 in a substantially horizontal direction toward the other measuring unit that moves with respect to each other. It should be noted that the light emitting diode 33 is mounted only in a predetermined angle range of the cylinder 32 so that the light emitting diode 33 is not in all directions but a predetermined angle (for example, the angle range is
It is also possible to irradiate the modulated light only to 0 degree, 90 degree, etc. (see FIG. 4).

Although the wavelength of the light emitting diode 33 is not particularly limited, it is desirable to use near infrared rays in order to avoid the influence of noise due to ambient light or dust as much as possible, and it is particularly desirable to use the wavelength of about 0.8 to 1.5 μm. Then, the signal processing frequency in the measurement units 4 and 5 (for example, 12.8 MH)
It is desirable to use a high speed type light emitting diode capable of modulating the light output in the order of, for example, 10 MHz so that it can easily respond to z).

To receive an optical signal, a plurality of optical sensors 35 are attached to the side surface of a cylinder 34 which is an optical sensor holding member formed coaxially with the cylinder 32. For example, from all horizontal directions (angle range of 360 degrees). The modulated light of can be received. As the optical sensor 35, it is desirable to use an avalanche photodiode capable of high-speed optical response. In addition, the optical sensor 35 is attached only to a predetermined angle range of the cylinder 34,
The desired angle (for example, an angle range of 180
It is also possible to make it possible to receive only the modulated light from a light source (see FIG. 4). Further, the optical sensor holding member is not limited to a column, and its cross section can be a polygon such as a regular hexagon or a regular octagon.

The numbers and arrangements of the light emitting diodes 33 and the photosensors 35 may be determined depending on their light distribution characteristics and required use conditions such as light output. As the optical sensor 35, an ordinary optical sensor having a light receiving range of directivity of 50 ° to 60 ° can be used. It is also possible to house the measuring units 4, 5 in a holding member 32 or 34 formed to have a housing structure.

When the light emitted from the light emitting diode 33 may be directly transmitted to the light sensor 35, it is desirable to attach a light shielding member 36 between the light emitting diode 33 and the light sensor 35 as shown in FIG.

The size of the optical transmitter / receiver 37 (for example, the cylinder 32,
The diameter of 34 depends on the distance between the respective transmitters / receivers used (between the stations), and the larger the distance, the larger the light output and the light receiving area, for example. When the distance between transmitters and receivers is in the order of 10 m, such as in a field or in a factory, the diameter can be set to about 5 cm to 15 cm.

The optical transmitter / receiver 37 configured as described above
Are attached to each of the two points for measuring the distance from each other.
Two points may move both in addition to the case where only one moves. As shown in FIG.
An embodiment in which optical transceivers 43 and 44 are attached to a vehicle A41 and a vehicle B42 is shown. Arrows a45 and b46 in the figure indicate modulated light signals emitted from the vehicle A41 and the vehicle B42, respectively. Since light is radiated in all horizontal directions, modulated light can always be transmitted and received to each other no matter how the vehicle orientation or positional relationship changes on a horizontal plane.

Note that, for example, when the orientations and positional relationships between the objects to be measured are limited and it is not necessary to perform optical transmission / reception in all directions, a part of the light emitting diode and the optical sensor is omitted as shown in FIG. The optical transmitter / receiver 57 may be formed. A plurality of light emitting diodes 53 are attached to a limited side surface of a cylinder 52 vertically held by a support column 51, and emit light at a limited angle. Further, an optical sensor 55 is attached to a part of a side surface of a cylinder 54 coaxial with the cylinder 52 so that only light from a limited direction corresponding to the light irradiation direction can be received. As in the example of FIG. 2, a light shielding plate 56 may be attached between the light emitting diode 53 and the optical sensor 55.

In the above optical transposer system according to the present invention,
Considering only the principle, the transmission frequency f ₁Even stable
Other factors will not affect the distance measurement.
It However, in order to actually make high-precision measurements, there are other requirements.
Is also necessary.

First, assuming that the detection resolution of Δφ is constant, the resolution of distance measurement is inversely proportional to ω _{1, that} is, the transmission frequency f ₁ , as can be seen from equation (10). Therefore, in order to make the resolution of the distance measurement fine, it is necessary to increase the transmission frequency f ₁ . In the present embodiment, f ₁ is set to 12.801M
It was set to Hz. In this case, if the resolution of the phase difference detection is 1/10000 of the cycle, the resolution of the distance measurement is about 1.
2 mm.

F_TwoCan be set in principle
It seems that the ₁Limited in relation to
Be done. Accurate transmission, amplification and phase comparison of beat signals
To do this, the frequency f of the beat signal₁-F_TwoThe electrical
It must be set to a frequency that is easy to handle. Real
In the embodiment, f_TwoTo 12.8MHz and
Signal is set to 1 kHz.

In principle, even if the frequency of the beat signal fluctuates, it does not affect the measurement, but in reality, there is a possibility that the signal processing in the low-pass filter or the phase difference detection circuit may be hindered. Therefore, it is necessary to prevent the value of f ₁ -f ₂ from changing. When the transmission signals from both AB stations are generated by independent oscillators, f ₁ or f
_{Even if 2} is changed slightly, the difference f ₁ −f ₂ changes at a large rate. For example, in the case of the present embodiment, f ₁ −f ₂ is 1.28 due to a change in f ₂ of 1 ppm.
%Change. In order to avoid this, in the present embodiment, the oscillator 87 of the B station is a temperature-compensated crystal oscillator with a small frequency fluctuation (frequency fluctuation: ± 1 ppm), and the oscillator frequency is set so that the beat signal frequency is always 1 kHz at the A station. f ₁
To control.

FIG. 5 is a block diagram showing an embodiment of a signal processing circuit in the distance measuring system 61 between stations A and B according to the present invention. In this embodiment, the ranging system 61 includes at least two measuring units 64 at stations A and B,
65 respectively. For transmission of the beat signal from the B station 63 to the A station 62, an independent transmission system such as the beat signal transmitter 19 of FIG. 1 may be used, but in reality, the optical signal y
Often, the _two optical transmitters 90 are used together. Also in the embodiment shown in FIG. 5, the beat signal of 1 kHz is modulated by the modulated light 81.
The signal is transmitted from the optical transmitter 90 together with the y ₂ signal.

Basically, from the A station 62 and the B station 63, infrared modulated lights 80 and 81 intensity-modulated by electric signals of 12.801 MHz and 12.8 MHz are respectively transmitted from the optical transmitter 68,
90 to transmit to each other. The optical transmitters 68 and 90 are high-speed infrared LEDs (light emitting diodes) generally used for generating optical signals, and the optical receivers 70 and 82 are commonly used APDs (avalanche) capable of sensing high frequency intensity modulation. It is better to use a photodiode.

In the station B 63, it is desirable to use a temperature compensation type crystal oscillator as the oscillator 87 to generate a signal of 12.8 MHz. The 12.8 MHz transmission signal and the reception signal from the A station 62 are mixed by the mixer 83, and the LPF
A (low-pass filter) 84 extracts only the low-frequency beat signal of 1 kHz. This is the waveform shaper 85
Then, the signal is shaped into and input to a VCO (voltage controlled oscillator) 86 to generate a 450 kHz signal frequency-modulated at 1 kHz. Next, adder 88 outputs 12.8 MHz and 4
The voltage fluctuation of 50 kHz is added to generate a signal of 12.8 MHz that is offset-modulated at 450 kHz, and the optical transmitter 90 puts the modulated light 81 on the modulated light 81 and the stations B 63 to A 6.
Send to 2.

At station A 62, the modulated light 81 sent from station B
Is received by an optical receiver (APD) and divided into two, one of which is a BPF (bandpass filter) 71 of 450 kHz.
The other is input to the mixer 69. The signal near 450 kHz passing through the BPF 71 is demodulated by the FM demodulator 72 to reproduce the 1 kHz signal sent from the B station. On the other hand, in the mixer 69, 12.801 MH generated at station A
The z signal and the received signal of 12.8 MHz from the B station are mixed and passed through the LPF 75 to obtain a beat signal of 1 kHz. The two beat signals thus obtained are respectively shaped by the waveform shapers 73 and 76 and their phases are compared. From this phase difference, the distance can be obtained based on the above-mentioned principle.

In order to maintain the frequency of the beat signal at exactly 1 kHz, the frequency of the high frequency signal generated by the A station 62 is controlled. The frequency of the 2 MHz crystal oscillator 77 is divided by the frequency divider 78 to obtain a 1 kHz reference signal. The VCO 66 is controlled by a PLL (phase lock loop) 79 so that the reference signal and the beat signal from the waveform shaper 76 have the same frequency, and 12.801 MHz is generated.
As a result, the beat signal is maintained at 1 kHz even if the transmission frequency at station B fluctuates.

FIG. 6 is an example of a circuit of an embodiment of a part related to the optical transmitters 68 and 90. An electric signal is input through the tuning section 92, and the light emitting diode 95 of the light emitting section 94 is driven through the amplifying section 93 to perform optical transmission. In this example, five light emitting diodes 95 are connected in series to form one set,
The pairs are operating in parallel.

FIG. 7 shows another embodiment of the optical receiver.
The light receiving section may use a reflector to obtain a wide reception angle instead of using a large number of optical sensors 35 arranged over the entire circumference of the cylinder 34 as shown in FIG. FIG. 7 shows a cross-sectional view of an optical receiver 101 that receives light from all horizontal directions using one optical sensor and a reflector.

The container 106 in which the optical sensor 102 is arranged is, for example, a light receiving window 10 formed of an optical filter for shielding noise.
Have three. The light receiving window 103 is not limited to the optical filter and may be formed of a transparent plate such as ordinary glass or plastic. The pillar 10 is provided on the light receiving window 103.
The reflection plate 105 can be attached via 4. Reflector 105
The shape of the modulated light from each direction is the optical sensor 10
There is no particular limitation as long as the light can be condensed to 2, but a parabolic shape as shown in FIG. 7 described below is more preferable.

In FIG. 7, z in the orthogonal coordinate system is vertically upward.
Take the axis and take the x-axis in any direction in the horizontal plane. The z axis is aligned with the center line of the device, and the center of the light receiving surface of the optical sensor 102 is located at the origin of the coordinates. The reflecting surface of the reflecting plate 105 has a shape of a rotating surface which is formed by rotating a part of the parabola d opened in the x-axis direction around the z-axis, with the origin of the coordinates as the focal point. The parabola d is expressed by the following equation.

X = az ² −1 / (4a) (11) a is a constant having a dimension of (length) ⁻¹ . As shown, the distance from the apex of the parabola to the focal point is 1 / (4a), the distance from the intersection of the parabola and the z axis to the focal point is 1 / (2a),
Is. In the embodiment of the present invention, this distance 1 / (2a)
Is 5 to 10 cm.

By applying the distance measuring method described above, not only the distance to the moving body but also the position of the moving body can be measured. The position measuring system 1 shown in FIG.
11 shows an embodiment of the present invention as 11.

Of the distance measuring devices described above, the A unit (A
Station 112 is fixed, and device B (station B) 114 is mounted on a moving body 115 to be measured. Further, a C unit 113 having an optical receiver and a signal processing device equivalent to the A unit or the B unit is connected to the A unit.
It is fixed at a position apart from the device A separately from the device 112.

Between the A unit 112 and the B unit 114, the modulated lights a and b modulated by the high frequency signals of the frequencies f ₁ and f ₂ are exchanged as described above, and the low frequency of the frequency f ₁ -f ₂ is exchanged. Generates beat signals respectively.

The low frequency beat signal obtained by the B unit is the B unit 1
It is sent in all directions on the modulated light b sent from 14. In this way, the low frequency beat signal from the B unit 114 is received not only by the A unit but also by the C unit 113.

On the other hand, the low-frequency beat signal obtained by the A-unit 112 is sent to the C-unit 113 on the high-frequency signal having the frequency f ₁ . The transmission of this signal from the A device 112 to the C device 113 is performed only to the C device 113, for example, by using a light beam or a wire or the like directed only in the direction of the C device 113. Therefore, it does not affect the signal reception of the B unit 114. In this way, the beat signals obtained by the A unit 112 and the B unit 114 are sent to the C unit 113. Furthermore, in C unit 113, A
The high frequency signal f sent from the device 112 and the high frequency signal b sent from the device B are mixed to create a beat signal independently.

By the above method, the C unit 113 can obtain three beat signals, and from the phase difference between them, between AB and B
Two pieces of distance information regarding C are obtained. When the distance between ACs is known, the distance between AB and BC is obtained, so that the position of the B vessel on the horizontal plane can be obtained.

Although several embodiments of the present invention have been illustrated and described above, the embodiments of the present invention described here are merely examples, and various embodiments are possible without departing from the technical scope of the present invention. It is obvious that a modification of is possible.

The invention of the present application is not limited to the above-described embodiment, and can be variously modified at the stage of implementation without departing from the spirit of the invention. Furthermore, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all constituent elements shown in the embodiment, at least one of the problems described in the section of the problem to be solved by the invention can be solved, and it is described in the section of the effect of the invention. If at least one of the effects is obtained, the effect in which this constituent element is deleted can be extracted as the invention.

[0070]

As is apparent from the above description, according to the present invention, the following advantages are obtained when the distance between two points is measured by the optical transponder system using diffused light emitted in a wide angle range. It is a thing.

(1) Even if the relative azimuths of the two objects for which distance measurement is required change, it is not necessary to move the transmitter / receiver toward the other party, so an automatic tracking device is not required, and a scanning device is also required. Therefore, the structure is simpler than that of the conventional optical distance measuring device, and it can be manufactured at low cost.

(2) Since the distance is obtained by measuring the phase difference between continuous waveforms, the distance can be measured with high accuracy.

(3) It is safer in operation and easier to handle than a system using a laser beam with high light intensity.

(4) Since radio waves are not used, the system is not restricted by the Radio Law and has a high degree of freedom in system configuration.

Therefore, according to the present invention, there is provided a distance measuring device which is highly accurate, inexpensive and easy to handle. As a result, it is possible to obtain the effects of measuring the position of the moving body, improving the accuracy of the control system, and reducing the cost.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining the basic principle of an optical transponder distance measuring system according to the present invention.

FIG. 2 is a diagram showing an example of an embodiment of an optical transceiver according to the present invention.

FIG. 3 is a diagram showing an embodiment in which the optical transceiver according to the present invention is attached to vehicles A and B which are moving bodies.

FIG. 4 is a diagram showing an optical transceiver in which a light emitting diode and an optical sensor are arranged only on a part of the circumference.

FIG. 5 is a block diagram showing signal processing in the optical distance measuring apparatus of the present invention.

FIG. 6 is a diagram showing a circuit example of a portion related to an optical transmitter.

FIG. 7 is a sectional view showing an embodiment of an optical receiver having a reflector.

FIG. 8 is a schematic diagram relating to position measurement of a moving body that is an embodiment of the present invention.

FIG. 9 is a schematic diagram showing a distance measuring method by a conventional tracking type lightwave distance measuring device.

FIG. 10 is a schematic diagram showing a distance measuring method using a conventional laser scanner.

FIG. 11 is a schematic diagram showing a distance measuring method using a conventional light beam transponder.

FIG. 12 is a schematic diagram showing a conventional distance measuring method for transmitting and receiving radio waves to measure a distance.

[Explanation of symbols]

1 ... Distance measuring system, 2 ... Station A, 3 ... B
Station, 4 ... Measuring unit, 5 ... Measuring unit, 6 ... Oscillator A, 7 ... Oscillator B, 8 ...
Optical transmitter A, 9 ... Optical transmitter B, 10 ... Optical receiver A, 11 ... Optical receiver B, 12 ... Modulated light, 13 ... Modulated light, 14 ... Mixer, 15
… Mixer, 16… Low-pass filter, 17
... low-pass filter, 18 ... beat signal receiver, 19 ... beat signal transmitter, 20 ... phase comparator, 31 ... pillar, 32 ... light emitting diode holding member, 33 ... light emitting diode, 34 ...
Optical sensor holding member, 35 ... Optical sensor, 36
... light-shielding member, 37 ... optical transceiver, 41 ... vehicle, 42 ... vehicle, 43 ... optical transceiver, 4
4 ... Optical transceiver, 45 ... Modulated optical signal, 46
... modulated light signal, 51 ... pillar, 52 ... cylinder, 53 ... light emitting diode, 54 ... cylinder,
55 ... Optical sensor, 56 ... Shading plate, 57 ...
Optical transceiver, 61 ... Distance measuring system, 62 ...
Station A, 63 ... Station B, 64 ... Measuring unit, 65 ... Measuring unit, 66 ... VCO,
67 ... Amplifier, 68 ... Optical transmitter, 69 ...
Mixer, 70 ... Optical receiver, 71 ... BPF,
72 ... FM demodulator, 73 ... Waveform shaper,
75 ... LPF, 76 ... Waveform shaper, 77
… Crystal oscillator, 78… Divider, 79… PL
L, 80 ... Modulated light, 81 ... Modulated light, 82
... Optical receiver, 83 ... Mixer, 84 ... L
PF, 85 ... Waveform shaper, 86 ... VCO,
87 ... Oscillator, 88 ... Adder, 89 ... Amplifier, 90 ... Optical transmitter, 92 ... Tuning section,
93 ... Amplifying section, 94 ... Light emitting section, 101 ...
Optical receiver, 102 ... Optical sensor, 103 ... Light receiving window, 104 ... Support, 105 ... Reflector,
106 ... Container, 111 ... Position measuring system,
112 ... A instrument, 113 ... C instrument, 114 ...
B instrument, 115 ... Moving body, 121 ... Optical wave rangefinder, 122 ... Moving body, 123 ... Reflector, 124 ... Light beam, 125 ... Reflected light,
126 ... Distance measuring device, 127 ... Microwave, 128 ... Reflector, 129 ... Distance measuring device, 130 ... Light beam, 131 ... Light beam, 132 ... Radio wave, 133 ... Radio wave, 134
… Distance measuring instruments,

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-126028 (JP, A) JP-A-5-273350 (JP, A) JP-A-7-210773 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01S 5/00 G01S ⁷ /00-7/64 G01S 13/00-17/95 G05D 1/00-1/12 H04B 10/00

Claims (3)

(57) [Claims] 1. An optical transponder distance measuring device having a first measuring unit and a second measuring unit, wherein the first measuring unit is a first electrical device that generates an electrical signal of a first frequency. Signal generation means, and first optical transmission that is connected to the first electric signal generation means and emits first modulated light modulated by the electric signal of the first frequency in a predetermined direction in a first angular range. A second electric signal generating means for generating an electric signal having a second frequency, and a second optical receiving means for receiving the first modulated light and demodulating it into an electric signal. Means, second beat signal generating means for mixing the electric signal of the second frequency and the electric signal demodulated by the second optical receiving means to generate a second beat signal, and electric means of the second frequency Signal and the second beat signal A calculation and a pressure calculation unit that generates a sum signal, a second light transmission means for radiating a second light modulated by the sum signal in a predetermined direction at a second angle range, the first The first measurement unit further includes a first optical receiving unit that receives the second modulated light and demodulates it into an electrical signal, an electrical signal of the first frequency, and an electrical signal demodulated by the first optical receiving unit. A first beat signal generating means for mixing a signal and generating a first beat signal; and an electric signal demodulated by the first optical receiving means,
A demodulation means for generating a demodulated second beat signal; and a phase comparison means for detecting and outputting a phase difference between the first beat signal and the demodulated second beat signal. Distance measuring device. 2. A method for measuring the position of a moving body, the method comprising :
Was positioned at a distance spaced position, placing the second measurement unit to the <br/> mobile, the first measurement unit generates a first high-frequency signal of frequency f _1, the second A step of generating a second high frequency signal having a frequency f ₂ by the measuring unit, and a step of generating the first modulated light modulated by the first high frequency signal and radiating the first modulated light in a predetermined direction. And a step in which the second measurement unit generates second modulated light modulated by the second high-frequency signal and emits the second modulated light in a predetermined direction; and the first measurement unit outputs the second modulated light. received to generate a first low frequency beat signal of a frequency f ₁ -f _2, the second of the second low-frequency beat signal measurement unit to receive the first modulated light frequencies f ₁ -f ₂ To generate the second measurement unit. Radiating the second low-frequency beat signal on the second modulated light, and the third measurement unit receives the second modulated light having the second low-frequency beat signal. The step of transmitting the first low-frequency beat signal to the third measurement unit by the first measurement unit adding the first low-frequency beat signal to the first high-frequency signal; and transmitting the first low-frequency beat signal to the third measurement unit. Receiving the first high frequency signal including the first high frequency signal, the third measurement unit demodulating the first high frequency signal sent from the first measurement unit, and The second modulated light sent from the second measurement unit is demodulated, and the frequency f ₁ − is generated based on these two demodulated signals.
generating a third low-frequency beat signal f _2, the steps of the third measuring unit performs phase comparison between the first, second and third low-frequency beat signal from their phase difference A method for measuring the position of a moving body, which comprises the step of obtaining distances between the first and second measurement units and between the second and third measurement units to obtain the position of the second measurement unit. . 3. A method for measuring a distance to a moving body.
Te, the first measurement unit and the third measurement unit given
The second measurement unit is placed at a position separated by a distance.
Arranging in a moving body, said first measuring unit having a first high frequency signal of frequency f ₁ .
Signal is generated by the second measurement unit at a _second frequency of frequency f ₂ .
Generating a high frequency signal, the first measuring unit modulating with the first high frequency signal
Of the first modulated light generated and emitted in a predetermined direction.
And the second measurement unit modulates with the second high frequency signal.
Of the second modulated light generated and emitted in a predetermined direction.
And the first measurement unit receives and monitors the second modulated light.
Generate a first low frequency beat signal of wavenumber f ₁ -f ₂ ,
The second measuring unit receives the first modulated light and
A step for generating a second low frequency beat signal of the number f ₁ −f ₂ .
And the second measurement unit causes the second low frequency beat signal to
Radiating the light on the second modulated light, the second modulated light having the second low-frequency beat signal
Is received by the third measurement unit, and the first measurement unit receives the first low frequency beat signal.
On the first high-frequency signal, the third measurement unit
Transmitting only the bets, the first high-frequency signal including the first low-frequency beat signal
Signal is received by the third measuring unit, and whether the third measuring unit is the first measuring unit.
Demodulates the first high frequency signal sent from the
Demodulates the second modulated light sent from the second measurement unit
Then, based on these two demodulated signals, the frequency f ₁ −
generating a third low-frequency beat signal f _2, the third measuring unit is the first, second and third
The phase comparison of the low frequency beat signals and the phase difference between the first and second measurement units or
Determining the distance between the second and third measuring units;
For measuring the distance to a moving object characterized by having
Law.