JPH07301673A - Speedometer, speed detection method, and displacement information detection device - Google Patents

Abstract

PURPOSE:To provide a speedometer that can detect the speed information of a moving object with high accuracy utilizing a Doppler signal and an index signal. CONSTITUTION:Luminous flux from a light source means 101 is made enter the detected face of a moving object 107. Scattered light subjected to Doppler shift from the moving object 107 is detected by a photo detector 1, and the speed information of the moving object 107 is detected from a signal obtained by inputting a signal from the photo detector 1 into a Doppler signal processing circuit 21. In addition, the signal from the photo detector 1 is inputted to an index signal processing circuit 22 to obtain an index signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a speedometer, a speed detecting method,
Alternatively, with respect to the displacement information detecting device, for example, a moving object, a fluid, or the like (hereinafter referred to as “moving object”) is irradiated with laser light, and the frequency of scattered light subjected to Doppler shift according to the moving speed of the moving object is detected. It can be successfully applied to a speedometer using the Doppler effect, which measures the displacement information about the displacement of the moving object and the moving speed of the moving object in a non-contact manner by detecting the index signal that is the reference for the deviation and the measurement position. It is a thing.

[0002]

2. Description of the Related Art Conventionally, a laser Doppler velocimeter has been used as an apparatus for measuring the moving speed of a moving object in a non-contact and highly accurate manner. The laser Doppler velocimeter irradiates a moving object with a laser beam, and the frequency of scattered light from the moving object shifts in proportion to the moving speed of the moving object (Doppler effect) is utilized, that is, It detects the Doppler signal and measures the moving speed of a moving object.

When detecting movement information of a moving object, a reference signal of a measurement start position may be used. At this time, conventionally, in addition to the photodetector for detecting the Doppler signal, a photodetector for obtaining an index signal serving as a reference of the measurement start position is provided.

[0004]

Conventionally, in addition to the photodetector for detecting the Doppler signal, a photodetector for obtaining the index signal is separately provided. For this reason, when two photodetectors are provided to face a moving object, the whole device tends to be complicated when the moving object is small.

The present invention detects scattered light including a Doppler signal and an index signal from a moving object with one photodetector for detecting the Doppler signal, and processes the signal from the photodetector with a proper configuration. An index signal is obtained together with a Doppler signal by processing using a circuit, whereby a speedometer, a speed detection method, and a displacement information detection device capable of highly accurately detecting movement information of a moving object with a simple configuration. For the purpose of provision.

[0006]

The speedometer of the present invention comprises: (1-1) a light beam from a light source means is made incident on a surface to be inspected of a moving object, and scattered light from the moving object which has undergone a Doppler shift is generated. The signal from the photodetector is detected, the speed information of the moving object is detected from the signal obtained by inputting the signal from the photodetector to the Doppler signal processing circuit, and the signal from the photodetector is index signal processed. It is characterized in that the index signal is obtained by inputting to the circuit.

In particular, the index signal processing circuit has a frequency filter, and the control unit changes the cutoff frequency of the frequency filter based on the velocity information of the moving object to obtain the index signal. It has a feature.

According to the velocity detecting method of the present invention, (1-2) the light beam from the light source means is incident on the surface to be inspected of the moving object, and the scattered light which has undergone the Doppler shift from the moving object is detected by the photodetector. Then, when detecting the velocity information of the moving object using the signal from the photodetector, a part of the moving object has a diffuse reflectance different from the diffuse reflectance of the test surface,
Further, it is characterized in that an index mark smaller than the diameter of the light flux incident on the surface to be inspected is formed.

In particular, the photodetector detects scattered light from an index mark provided on the moving object and obtains an index signal from the scattered light.

(1-3) The light beam from the light source means is made incident on the surface to be detected of the moving object, the scattered light which has undergone the Doppler shift from the moving object is detected by the photodetector, and the scattered light from the photodetector is detected. While detecting the velocity information of the moving object from the signal obtained by inputting the signal to the Doppler signal processing circuit, a diffuse reflectance different from the diffuse reflectance of the test surface provided in a part of the moving object is set. Scattered light from the index mark that has and is smaller than the diameter of the incident surface incident light beam is detected by the photodetector, and the signal from the photodetector is input to the index signal processing circuit to obtain the index signal. It is characterized by being.

In particular, the index signal processing circuit has a low-pass filter, a high-pass filter, an amplifier, a level detector and an index generator, and the cutoff frequencies of both filters are controlled by the control unit based on the velocity information of the moving object. The feature is that the index signal is obtained from this.

The displacement information detecting apparatus of the present invention comprises (1-4) making the light beam from the light source unit incident on the surface to be inspected of the moving object, and the scattered light which has undergone the Doppler shift from the moving object being detected by the photodetector. The signal from the photodetector is input to the Doppler signal processing circuit to detect information related to the displacement of the moving object from the signal obtained, and the signal from the photodetector to the index signal processing circuit. The feature is that an index signal is obtained by inputting.

[0013]

Embodiment 1 FIG. 1 is a block diagram of the essential parts of Embodiment 1 of the present invention. The present embodiment shows a configuration for obtaining an index signal in a speedometer utilizing the Doppler effect.

In the figure, 21 is a Doppler signal processing circuit, 2
Reference numeral 2 is an index signal processing circuit. Reference numeral 1 denotes a photodetector, which detects both the scattered light that has undergone the Doppler shift from the test object (moving object) irradiated with the speed measurement light beam and the scattered light from the index mark, and outputs the output signal. It is output as S. A first amplifier 2 amplifies the output signal S from the photodetector 1. The amplifier 2 includes a Doppler signal and an index signal according to the speed of the object to be inspected, and outputs the signal as a signal according to the amount of diffused reflected light from the object to be inspected.

A second amplifier 3 amplifies the Doppler signal from the first amplifier 2 to a certain level.
Reference numeral 4 denotes a bandpass filter, which removes noise of the Doppler signal from the second amplifier 3. A waveform shaper 5 binarizes the Doppler signal from the bandpass filter 4. Reference numeral 6 denotes a frequency oscillator, which outputs the binarized Doppler signal from the waveform shaper 5 as a continuous signal.

In this embodiment, the Doppler signal processing circuit 21
From the binarized Doppler signal (Doppler frequency F) from, the movement information of the moving object is detected based on the equation described later.

Reference numeral 7 is a high-pass filter (HPF), which removes a variation of the signal due to the surface property of the object to be inspected from the signal corresponding to the light quantity of the diffuse reflection light including the index signal from the first amplifier 2. . A low pass filter (LPF) 8 removes the Doppler signal and high frequency noise from the high pass filter (MPF) 7. A third amplifier 9 amplifies the index signal from the low pass filter 8. 10 is a detector, the third
The index signal from the amplifier 9 is detected.

Reference numeral 11 is an index generator, which outputs an index signal of a certain width from the index signal from the detector 10. A control unit (control unit) 12 controls each of the elements 7 to 11. Control unit 1
Reference numeral 2 indicates, for example, the cutoff frequency of the high-pass filter 7 or the low-pass filter 8 (bandpass filter) based on the velocity information of the moving object from the Doppler signal processing circuit 21. Is getting

FIG. 3 is an explanatory view of the size of the index mark to be written on the test object when the index forming means forms the index mark on the test object in the present invention.

In the figure, 30 is an index mark, and 114a and 114b are the spot diameters of the laser beams that irradiate the object to be inspected. Index mark 3
0 is made smaller than the spots 114a and 114b where the two light fluxes of the laser Doppler velocimeter intersect.

3A shows the index mark 30 which is horizontally long in the moving direction, FIG. 3B shows the index mark 30 which is vertically long in the moving direction, and FIG.
Shows an example in which the index mark 30 is round. Further, the index mark to be written is such that its diffuse reflectance is low or high, which is different from the diffuse reflectance of the test object.

Next, a method of detecting and generating the index signal in this embodiment will be described. In FIG. 1, the first
The signal that includes the index signal from the amplifier 2 and that corresponds to the light amount of the diffuse reflected light includes the fluctuation of the low frequency signal due to the change of the reflected light amount due to the surface property of the object to be inspected, as shown by the signal waveform 2a in FIG. .

Therefore, the HPF 7 removes the fluctuation of the signal due to the surface property of the object to be inspected, and the LPF 8 removes the high frequency noise due to the Doppler signal or the like. Then, the index signal is efficiently amplified by the third amplifier 9 to obtain a signal like the signal waveform 2b in FIG.

Then, the setting of the index signal detection level in the detector 10 for detecting the level becomes easy based on the output level of the third amplifier 9, and malfunction can be eliminated. The index generator 11 sets the output width t of the index signal detected by the detector 10, and outputs the index signal from this.

Further, in the present invention, the velocity information of the object to be detected is detected based on the Doppler signal from the frequency oscillator 6, and the control unit 12 controls the HPF 7 and the LPF 8 based on the velocity information.
The cutoff frequency of is determined. Thus, the amplifier 9 can efficiently amplify the index signal. The cutoff frequency can be easily determined by knowing the size of the index mark, the diameter of the laser beam, and the speed of the object to be measured, because the width of the index signal in the graph 2a of FIG. 2 can be calculated.

Further, the index mark is made smaller than the spot diameter at which the two light beams intersect, which has almost no effect on the level of the Doppler signal and prevents deterioration of the measurement accuracy.

FIG. 4 is a schematic view of the essential parts of the optical system of the speedometer according to the present invention.

In the figure, 100 is a speedometer using the Doppler effect. 101 is a laser, 102 is a collimator lens, 107 is an object to be measured as a moving object, 110 is a diffraction grating with a grating pitch d, 121 and 122.
Is a convex lens having a focal length of f and has an arrangement configuration as shown in the figure. When the distance from the diffraction grating 110 to the lens 121 is a and the distance from the lens 122 to the object 107 to be measured is b, a and b satisfy the relationship of a + b = 2f.

Laser light from the laser diode 101 having a wavelength λ of about 0.68 μm is collimated by the collimator lens 10.
2 becomes a parallel light flux 103 with a diameter of 1.2 mmφ,
The light enters perpendicularly to the grating arrangement direction of the transmission type diffraction grating 110 having a grating pitch d of 3.2 μm. At this time, the ± 1st-order diffracted lights 105a and 105b are emitted at a diffraction angle θ ₁ = 12 °.

The light beams 105a and 105b have a focal length f (=
When incident on a 15 mm) convex lens 121, light fluxes 113a and 113b as shown in the figure are obtained. Luminous flux 113a, 1
When 13b enters another convex lens 122 separated by 2f (= 30 mm), parallel rays 114a and 114b are obtained again, and a spot diameter of 1.2 mmφ is formed at an angle equal to the diffraction angle θ ₁ from the diffraction grating 110 described above. Become speed V (m
The object to be measured 107 of (m / sec) is irradiated.

The light scattered by the object 107 to be measured is efficiently detected by the convex lens 122 and the condenser lens 108.
The light is collected on the light receiving portion 1a, and the optical signal containing the Doppler signal shown in the expression (a1) is detected. Then, the velocity information of the moving object 107 is obtained through a calculation unit (not shown) that receives an output from the Doppler signal processing circuit having the configuration shown in FIG.

F = 2V / d = V / 1.6 (kHz) (a1) Here, a = 10 mm and b = 20 mm, where b is relatively long and the working distance is large. The speed of installation of the speedometer is increased.

If the wavelength λ of the laser light from the laser diode 101 changes, the diffraction angle θ changes corresponding to dsin θ = λ, but the Doppler signal does not change. Further, in this device, the positions of the two light flux spots are also immovable. That is, the object 107 to be measured is set in the arrangement shown in FIG. The crossing condition is maintained and good Doppler and index signals are obtained.

[0034]

According to the first and seventh inventions, as described above,
The scattered light including the Doppler signal and the index signal from the moving object is detected by one photodetector for detecting the Doppler signal, and the signal from the photodetector is processed by using a signal processing circuit having an appropriate configuration. As a result, the index signal is obtained together with the Doppler signal, which makes it possible to achieve a speedometer or displacement information detection device that can detect movement information of a moving object with high accuracy with a simple configuration.

Further, according to the third to fifth inventions, when such an apparatus is used, it is possible to prevent the Doppler signal from being influenced even if the index mark is formed on the object to be inspected. Further, according to the second and sixth inventions, the effect that the index signal can be accurately obtained even if the velocity information of the object to be inspected changes can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an index signal detection method according to the present invention.

FIG. 3 is an explanatory diagram showing a relationship between an index mark and a spot light flux according to the present invention.

FIG. 4 is a schematic view of a main part of an optical system of a speedometer according to the present invention.

[Explanation of symbols]

 1 Photodetector 2 1st amplifier 3 2nd amplifier 4 Bandpass filter 5 Waveform shaper 6 Frequency oscillator 7 Highpass filter 8 Lowpass filter 9 3rd amplifier 10 Detector 11 Index generator 12 Controller 21 Doppler signal processing circuit 22 Index Signal processing circuit 100 Speedometer 101 Light source means 107 Moving object

Claims (7)

[Claims] 1. A light beam from a light source means is incident on a surface to be inspected of a moving object, a scattered light subjected to a Doppler shift from the moving object is detected by a photodetector, and a signal from the photodetector is detected by Doppler. The speed information of the moving object is detected from the signal obtained by inputting to the signal processing circuit, and the signal from the photodetector is inputted to the index signal processing circuit to obtain the index signal. Speedometer. 2. The index signal processing circuit has a frequency filter, and a cutoff frequency of the frequency filter is changed by a control unit based on velocity information of the moving object, and an index signal is obtained from this. The speedometer according to claim 1, which is characterized in that 3. A light beam from a light source means is made incident on a surface to be inspected of a moving object, and scattered light which has undergone the Doppler shift from the moving object is detected by a photodetector, and a signal from the photodetector is used. When detecting the velocity information of the moving object, an index mark having a diffuse reflectance different from the diffuse reflectance of the test surface and smaller than the diameter of the light flux incident on the test surface is provided on a part of the moving object. A speed detection method characterized by being formed. 4. The speed detecting method according to claim 3, wherein the photodetector detects scattered light from an index mark provided on the moving object and obtains an index signal from the scattered light. 5. A light beam from a light source means is incident on a surface to be inspected of a moving object, a scattered light subjected to a Doppler shift from the moving object is detected by a photodetector, and a signal from the photodetector is Doppler. While detecting the velocity information of the moving object from the signal obtained by inputting to the signal processing circuit, having a diffuse reflectance different from the diffuse reflectance of the test surface provided in a part of the moving object, And the scattered light from the index mark smaller than the diameter of the light flux incident on the test surface is detected by the photodetector, and the signal from the photodetector is input to the index signal processing circuit to obtain the index signal. Characteristic speed detection method. 6. The index signal processing circuit includes a low-pass filter, a high-pass filter, an amplifier, a level detector, and an index generator, and a cutoff frequency of both filters is controlled by a control unit based on velocity information of the moving object. 6. The speed detecting method according to claim 5, wherein the index signal is obtained from the index signal. 7. A light beam from a light source means is incident on a surface to be inspected of a moving object, a scattered light subjected to a Doppler shift from the moving object is detected by a photodetector, and a signal from the photodetector is detected by the Doppler. Information related to the displacement of the moving object is detected from the signal obtained by inputting to the signal processing circuit, and the signal from the photodetector is input to the index signal processing circuit to obtain the index signal. Displacement information detection device.