JPH07151771A - Spatial filter type speed-measuring instrument and speed control system and automobile with the instrument - Google Patents

Abstract

PURPOSE:To provide an inexpensive spatial filter type speedmeasuring instrument which can detect the moving direction of an object to be measured without using any special moving direction detecting device and has a compact constitution and light weight. CONSTITUTION:Moving direction detecting CCDs 16 and 26 are provided in the advancing direction of an object to be measured separately from a speed detecting spatial filter type photoreceptor 5. The correlation peak values VF and VB between the output of one CCD 16 or 26 at a certain time and the output of the other CCD 26 or 16 at another time are computed. When the peak values VF and VB are compared with each other, the moving direction of the object to be measured can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spatial filter type speed measuring device for detecting a ground speed of an automobile or the like in a non-contact manner, and to a function of discriminating a moving direction of the device. Further, the present invention relates to a speed control system and a vehicle equipped with the device.

[0002]

2. Description of the Related Art Conventionally, in this type of spatial filter type velocity measuring device, the velocity is usually measured by utilizing the fact that the center frequency of the spatial filter output is proportional to the velocity. Since the center frequency does not change depending on the positive / negative moving direction, the positive / negative moving direction cannot be discriminated. Therefore, when the speed measuring device of the present method is applied to the traction control system, there is a problem that the controller cannot determine whether the vehicle has started normally on the uphill road or whether the tire has slipped backward while moving backward.

As a solution, for example, Japanese Patent Laid-Open No. 52-
There is a measure as shown in Japanese Patent No. 133265. In this measure, by using a slit row rotor in the spatial filter unit, a carrier component proportional to the rotation speed of the rotor is added to the detection signal by the spatial filter, so that the speed in the positive and negative directions can be detected.

[0004]

However, since the slit row rotor as described above is required to have some flatness, there is a problem that the radius of the rotor becomes large and the size of the apparatus becomes large. Further, since the rotor needs to be rotated at a constant speed, which requires a high-precision motor, there is a problem that the device becomes expensive and heavy.

The present invention has been made in order to solve the above-mentioned problems, and the light intensity distribution is measured twice in the moving direction of the object to be measured, and the correlation peak value is calculated from this measurement result. By making it possible to determine the moving direction of the measurement object, the slit row rotor becomes unnecessary,
An object of the present invention is to provide a compact, inexpensive, and lightweight spatial filter type speed measuring device, a speed control system including the same, and an automobile.

[0006]

In order to achieve the above object, the invention of claim 1 comprises a spatial filter for extracting a signal of a specific spatial frequency component from light from an object to be measured, and the output of this spatial filter In a spatial filter type velocity measuring device for detecting a relative moving velocity of a measuring object based on a signal, a plurality of light receiving element arrays arranged in the traveling direction of the measuring object and one light receiving element array at a certain time And a calculating means for calculating a correlation peak value between the output and another light receiving element array output at a different time, and detecting the moving direction of the measurement object based on the correlation peak value calculated by the calculating means. It is the one. The invention according to claim 2 is provided with a spatial filter for extracting a signal of a specific spatial frequency component from the light from the measuring object, and a spatial filter method for detecting the relative moving speed of the measuring object based on the output signal of this spatial filter. In the speed measuring device,
Correlation between one light receiving element array arranged in the traveling direction of the measurement object and the output of a certain area of the light receiving element array at a certain time and the output of another area of the light receiving element array at another time A calculation means for calculating a peak value is provided, and the moving direction of the measurement object is detected based on the correlation peak value calculated by the calculation means.

According to a third aspect of the present invention, the light-receiving element array is arranged close to the light-receiving element of the spatial filter, and one imaging optical system measures both the light-receiving element of the spatial filter and the light-receiving element array. The spatial filter type velocity measuring device according to claim 1 or 2, wherein an image of an object is formed. A fourth aspect of the present invention is the method according to any one of the first to third aspects, in which the timing at which the light receiving element array output signal is taken in by the calculating means for calculating the correlation peak value is changed according to the detection speed of the speed measuring device. It is a spatial filter type velocity measuring device. In the invention of claim 5, the light receiving element array is CC
The spatial filter type velocity measuring device according to any one of claims 1 to 4, wherein D is D. The invention according to claim 6 has a pulse lighting light source for irradiating the measurement object, and the CCD receives the reflected light from the measurement object in synchronization with the lighting timing of the pulse lighting light source. It is the described spatial filter type velocity measuring device.

According to a seventh aspect of the present invention, there is provided a pulse lighting light source for irradiating the measurement object, and the CCD receives the reflected light from the measurement object at both the lighting and non-lighting points of the pulse lighting light source. The spatial filter type velocity measuring device according to claim 5, wherein the difference is input to the calculating means. The invention according to claim 8 is provided with the spatial filter type speed measuring device according to any one of claims 1 to 7, and the speed is controlled by controlling the brake or the accelerator by the output of this device. System. The invention according to claim 9 is an automobile equipped with the speed control system according to claim 8.

[0009]

According to the first, second and fifth aspects of the invention, the light from the object to be measured is received by the light receiver and the light receiving element array of the spatial filter. Then, the relative moving speed of the measuring object is detected based on the output signal of the light receiver of the spatial filter, and the correlation peak value between one light receiving element array output at a certain time and another light receiving element array output at another time Is calculated by the calculating means, and the moving direction of the measuring object is detected based on the correlation peak value. At this time, when there are a plurality of light receiving element arrays, the correlation peak values are calculated for the outputs of different light receiving element arrays at different times, and when there is one light receiving element array, different areas of the light receiving element array are different at different times. The correlation peak value is calculated for the output of The light receiving element array may be a CCD.

According to the third aspect of the present invention, since the light receiving element array is arranged close to the light receiving element of the spatial filter, both the light receiving element of the spatial filter and the light receiving element array are formed by one imaging optical system. An image of the object to be measured is formed on, the relative moving speed of the object to be measured is detected from the light receiver output of the spatial filter, and the moving direction of the object to be measured is detected from the output of the light receiving element array. According to the configuration of the above-mentioned claim 4, the correlation peak can be reliably captured by changing the timing of capturing the light receiving element array output signal according to the detection speed, and the moving direction of the measurement object can be accurately detected. It

According to the structure of claim 6, the CCD receives the reflected light from the object to be measured in synchronization with the lighting timing of the light source, so that it is less affected by the ambient light. According to the configuration of claim 7, the CCD receives the reflected light from the measurement object both at the time when the light source is turned on and when the light source is not turned on, and the difference between them is calculated to obtain the correlation peak value. The correlation peak value is calculated only for the self-luminous component that is not affected by. According to the configurations of claims 8 and 9,
Based on the speed measurement output of the spatial filter type speed measuring device, the brake is controlled so that the braking distance of the automobile is the shortest, or the accelerator is controlled so that the acceleration of the automobile is the best.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an optical system of a spatial filter type velocity measuring device. This velocity measuring device is located at a position facing the measurement target 1 whose moving speed and movement direction are to be measured, and includes a light source 2 including a light emitting diode or the like for irradiating the measurement target 1 with light, and the measurement target 1 Light receiving lens 3 for receiving the reflected light of the light, telecentric slit 4 arranged on the image side focal plane of light receiving lens 3, and spatial filter type light receiving device 5 for detecting the relative moving speed of measuring object 1.
And two light-receiving element arrays 6 for detecting the positive and negative moving directions of the measuring object 1. Light receiving element array 6
Are arranged close to each other on the same plane as the light receiver 5, and the elements are arranged in a straight line in the traveling direction of the measuring object 1. The detection area A on the measuring object 1 is imaged by the light receiving lens 3 on the imaging area B including the light receiver 5 and the light receiving element array 6. In this way, since the measuring object 1 is imaged on both the light receiver 5 and the light receiving element array 6 by the light receiving lens 3, a new optical system is not required to detect the positive and negative moving directions of the measuring object 1. And is economical.

Since only the light rays parallel to the optical axis reach the image forming area B by the telecentric slit 4, the image forming magnification is constant regardless of the distance between the light receiving lens 3 and the measuring object 1, and no velocity error occurs. . Spatial filter type light receiver 5
Are two generally known comb-teeth shaped light receivers, and the differential output of each light receiver serves as the velocity signal of the measurement object 1. Specifically, the moving speed is detected by utilizing that the center frequency of the differential output is proportional to the speed of the measuring object 1. In addition,
Even if the light receiving element array 6 is a photodiode, CC
It may be D (charge coupled device).

Next, the operation of the above configuration will be described. Light source 2
The light emitted from is reflected by the measuring object 1 that moves relatively, and this reflected light is received by the light receiving lens 3. This light passes through the telecentric slit 4,
The light is received by the spatial filter type light receiver 5 and the light receiving element array 6. Then, based on the output signal of the light receiver 5, the relative moving speed of the measuring object 1 is detected by the speed measuring unit described later, and is measured by the positive / negative moving direction discriminating unit described later based on the output signal of the light receiving element array 6. The positive / negative moving direction of the object 1 is detected.

Next, as an example of the light receiving element array 6, CC
Taking D, the signal processing of the CCD output will be described. FIG. 2 shows a positional relationship between the CCD and the positive and negative moving directions of the measuring object 1. Two CCDs 16 (denoted as CCD (F)), 2
6 (denoted as CCD (B)) are arranged in a line in the moving direction of the object to be measured, and the moving direction is the forward direction from the CCD (B) 26 side to the CCD (F) 16 side. . Further, each CCD 16 and 26 takes in a light reception signal at times T1 and T2.

FIG. 3 shows an embodiment of the positive / negative moving direction discriminating section and the speed measuring section. The positive / negative moving direction discriminating unit uses the CC
The CCDs 16 and 26, including the D16s and 26s, are operated by being timed by the timing control circuit 34, and the output signals of the CCDs 16 and 26 are respectively output from the A / D converter 1.
It is stored in the memories 12, 13, 22, 23 via 1, 21.

Specifically, the CCD at time T1
The output of (F) 16 is stored in the memory (F1) 12, and the CCD
The output of (B) 26 is stored in the memory (B1) 22, and similarly, the outputs of the CCDs 16 and 26 at time T2 are stored in the memories (F2) 13 and (B2) 23, respectively.
Then, the correlator (F) 14 causes the memory (F2) 13
And the correlation peak value of the memory (B1) 22 is calculated, and the correlator (B) 24 calculates the memory (F1) 12 and the memory (B1).
2) The correlation peak value of 23 is calculated. Further, in the comparator 15, the correlation peak value VF which is the output of the correlator (F) 14 and the correlation peak value VB which is the output of the correlator (B) 24 are compared, and when VB <VF, the measurement object 1 Is determined to have moved in the positive direction, and in the negative direction when VB> VF, a determination signal is output.

On the other hand, the velocity measuring unit includes the spatial filter type photodetector 5, the output of the spatial filter type photodetector 5 is amplified by the amplifier 31, the center frequency is extracted by the center frequency estimating circuit 32, and the F / V is obtained. (Frequency / voltage)
The voltage is converted into a voltage by the conversion unit 33, and a voltage proportional to the speed of the measuring object 1 is output. Further, by using the output of the F / V conversion unit 33 as the control signal of the timing control circuit 34 of the positive / negative moving direction determination unit, the times T1 and T2 can be changed according to the moving speed of the measuring object 1, Correlation peaks can be captured with certainty. For example, if the imaging magnification of the optical system is m, the moving speed of the measuring object 1 is v, and the center distance between the CCD (F) 16 and the CCD (B) 26 is d, then T2-T1 = d / mv. As described above, the time T2 may be controlled.

FIG. 4 shows an example of the light intensity distribution on the road surface when the measuring object 1 is moving in the positive direction.
1 is an example of the light intensity distribution at 1, and (b) is an example of the light intensity distribution at time T2. As can be seen from the figure, the memory waveforms of the memory (B1) 22 storing the output of the CCD (B) 26 at time T1 and the memory (F2) 13 storing the output of the CCD (F) 16 at time T2 are almost the same. Similarly, the memory (F1) 12 storing the output of the CCD (F) 16 at time T1 and the CCD at time T2
The stored waveform is different from that of the memory (B2) 23 that stores the output of (B) 26. Therefore, as shown in FIG. 5A, the correlation calculation result of the stored waveforms of the memory (B1) 22 and the memory (F2) 13 shows a high peak value VF (output of the correlator (F) 14). On the other hand, as shown in FIG. 5B, the memory (F1) 12 and the memory (B2) 2
The correlation calculation result of the stored waveform of 3 shows a low peak value VB (output of the correlator (B) 24).

The comparison result of the correlation peak values is VB <VF, and it is determined that the measuring object 1 is moving in the positive direction. In this way, the positive and negative moving directions of the measuring object 1 can be determined by calculating and comparing the respective correlation peak values, so that the slit row rotor and the high-precision motor for rotating the rotor at a constant speed, which have been conventionally required, can be provided. It is not necessary, resulting in a compact, inexpensive and lightweight measuring device. The whole area or a part of each memory may be used for the correlation calculation. When the entire memory is used, an area where data is insufficient can be dealt with by extrapolating (extrapolating) the average value of the data stored in the memory.

Next, a modification of the above embodiment will be described. One light receiving element array, two light receiving element array 6
It may be possible to realize a function equivalent to. That is,
The area of one light receiving element array is divided into two, and the moving direction of the measuring object 1 is detected based on the correlation peak value between the output of one area at a certain time and the output of the other area at another time. In the case of such one light-receiving element array, unlike the case of the two light-receiving element arrays 6, the distance between the two regions cannot be physically separated, so that it is not suitable for detecting the positive / negative moving direction during high-speed movement. However, it is useful when it can be limited to low-speed movement.
The advantage is that the optical adjustment is easier than the case of using.

Further, a pulsed light source is used as the light source 2, and C
The CD may receive the reflected light from the measurement object 1 in synchronization with the lighting timing of the pulse lighting light source. Generally, in an optical measuring device, in order to remove the influence of ambient light, a light source is often pulse-lighted and synchronous detection is performed, so that it can be dealt with.

Further, a pulsed light source is used as the light source 2,
The reflected light from the measurement object 1 may be received at both the time when the light source is turned on and the time when the light source is not turned on, and the difference between them may be calculated and input to the memory as correlation value calculation data. As a result, only the self-luminous component is stored in the memory that stores the CCD output, and the correlation calculation can be performed more accurately.

FIG. 6 shows the structure of an antilock brake system (ABS) equipped with a spatial filter type speed measuring device and a wheel rotation speed sensor. The output of the spatial filter type speed measuring device 51 and the output of the wheel rotation speed sensor 52 are
It is input to the ABS ECU 53. The wheel rotation speed sensor 52 includes a magnetic rotor (tooth shape) 54 attached to a tire, and an electromagnetic pickup type sensor 55 that outputs a pulse according to the number of teeth of the rotor 54. The ECU 53 is a spatial filter type speed measuring device 51.
Output including the moving direction from the wheel and the wheel rotation speed sensor 5
A predetermined calculation is performed based on the output from 2 and an optimum brake control signal is output so that the braking distance becomes the shortest.

FIG. 7 shows an example of an automobile 56 equipped with the above ABS. By using the output signals of the spatial filter type speed measuring device 51 and the wheel rotation speed sensor 52, a speed control system such as an ABS that can control so that the brake does not lock or a traction control system (TCL) that can control the accelerator can be constructed. . Further, by mounting this speed control system on an automobile 56 such as a passenger car, a truck, a trailer, or a bus, efficient braking / accelerating ability can be obtained and the safety of the automobile 56 can be enhanced.

[0026]

As described above, according to the invention of claim 1,
Since the light receiving element array is arranged in the traveling direction of the measuring object and the moving direction of the measuring object is detected based on the correlation peak value calculated from the output of the light receiving element array, it is conventionally necessary to detect the moving direction. The existing slit row rotor is not required, and the device is compact, inexpensive and lightweight. In addition, a high-precision motor for rotating the slit row rotor at a constant speed is not required, and the upper limit of the ambient temperature of the electronic components used in this device is usually higher than that of the motor.
Improves reliability. According to the invention of claim 2, in addition to the above effect, one light receiving element array is useful when the object to be measured moves at a low speed, and is more useful than the case where a plurality of light receiving element arrays are used. , Optical adjustment becomes easy. According to the third aspect of the present invention, the light receiving element array is disposed in the vicinity of the light receiver of the spatial filter, so that the detection area on the measuring object is the light receiver of the spatial filter by one imaging optical system. Since an image is formed on an image forming area including both the light receiving element array for detecting the moving direction and a moving direction, a new optical system is not required for detecting the moving direction, and the cost is reduced.

According to the invention of claim 4, the timing of the two times at which the output of the light receiving element array is detected is changed according to the moving speed, so that the correlation peak can be surely caught and the moving direction of the measuring object. The detection result of will be accurate. According to the invention of claim 5, the light receiving element array is C
Since it is a CD, the size and weight of the device can be reduced. According to the invention of claim 6, since the CCD receives the reflected light from the measurement object in synchronization with the lighting timing of the light source, the influence of the ambient light can be removed, and the accurate movement direction of the measurement object. It can be detected.

According to the invention of claim 7, the reflected light from the object to be measured is received by the CCD at both the time when the light source is turned on and the time when the light source is not turned on, and the difference is input to the calculation means. The correlation peak value is calculated only for the self-luminous component, the correlation peak value can be calculated more accurately, and the moving direction of the measurement target can be detected with high accuracy.
According to the eighth and ninth aspects of the present invention, the output of the spatial filter type speed measuring device can be used to control the brake or the accelerator so that the braking distance becomes the shortest or the acceleration performance becomes the best. A shorter distance or good acceleration can be expected.

[Brief description of drawings]

FIG. 1 is a perspective view of a spatial filter type velocity measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship between a CCD and a positive / negative moving direction of a measurement object.

FIG. 3 is a block diagram of a positive / negative moving direction determination unit and a speed measurement unit.

4A is a diagram showing an example of light intensity distribution on a road surface at time T1, and FIG. 4B is a diagram showing an example of light intensity distribution on a road surface at time T2.

5A is a diagram showing a correlation calculation result of a correlator (F), and FIG. 5B is a diagram showing a correlation calculation result of a correlator (B).

FIG. 6 is a block diagram of an ABS.

FIG. 7 is a configuration diagram of an automobile including the ABS.

[Explanation of symbols]

 1 object to be measured 2 light source 5 spatial filter type light receiver 6 light receiving element array 14, 24 correlator 15 comparator 16, 26 CCD 34 timing control circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Takagi 10 Ouron Co., Ltd., Hanazono Dodocho, Ukyo-ku, Kyoto City, Kyoto Prefecture

Claims (9)

[Claims] 1. A spatial filter type velocity measurement device comprising a spatial filter for extracting a signal of a specific spatial frequency component from light from an object to be measured, and detecting a relative moving velocity of the object to be measured based on an output signal of the spatial filter. In the device, a plurality of light receiving element arrays arranged in the traveling direction of the measurement object, and a correlation peak value between one light receiving element array output at a certain time and another light receiving element array output at another time A spatial filter type velocity measuring device, comprising: a computing means for computing; and a moving direction of the measuring object is detected based on the correlation peak value computed by the computing means. 2. A spatial filter type velocity measurement device comprising a spatial filter for extracting a signal of a specific spatial frequency component from light from a measurement target, and detecting a relative moving velocity of the measurement target based on an output signal of the spatial filter. In the device, one light receiving element array arranged in the traveling direction of the measurement object, output of a certain area of the light receiving element array at a certain time, and output of another area of the light receiving element array at another time And a calculation means for calculating a correlation peak value with the calculation means, and the moving direction of the measuring object is detected based on the correlation peak value calculated by the calculation means. apparatus. 3. A light-receiving element array is disposed close to a light-receiving element of a spatial filter, and an image of an object to be measured is provided on both the light-receiving element of the spatial filter and the light-receiving element array by one imaging optical system. The spatial filter type velocity measuring device according to claim 1 or 2, wherein an image is formed. 4. The timing for fetching the light-receiving element array output signal to the calculating means for calculating the correlation peak value is changed according to the detection speed of the speed measuring device. The spatial filter type velocity measuring device described in 1. 5. The spatial filter type velocity measuring device according to claim 1, wherein the light receiving element array is a CCD. 6. A pulsed light source for irradiating an object to be measured, wherein the CCD receives reflected light from the object to be measured in synchronization with the lighting timing of the pulsed light source. The spatial filter type velocity measuring device according to claim 5. 7. A pulsed light source for irradiating an object to be measured, wherein the CCD receives reflected light from the object to be measured at both times of lighting and non-lighting of the pulsed light source, and a difference between them is calculated. The spatial filter type velocity measuring device according to claim 5, wherein the velocity measuring device is input to a computing means. 8. A spatial filter type speed measuring device according to claim 1, wherein the speed is controlled by controlling a brake or an accelerator according to the output of this device. Speed control system. 9. An automobile equipped with the speed control system according to claim 8.