JP2002131017A - Apparatus and method of distance measurement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus of distance measurement using a light-down method enabling to image a slit light precisely with making brightness distribution of the slit light to be imaged uniform. SOLUTION: In the apparatus of distance measurement to image a reflected light of a laser light emitted by itself and to measure a distance to a measured object with a position relation between a light-emitting position of the laser light and an imaging position, a laser light-emitting means to emit the laser light, a beam diffusion means to make the laser light emitted from the emitting means become the slit light with diffusion of the laser light in one direction, an image capture means to image the reflected light of the slit light on an object surface and an adjusting means of light intensity distribution mounted between the diffusion means and the object to adjust light intensity distribution of the slit light in the direction of beam diffusion of the slit light are equipped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device for imaging a reflected light of a laser beam emitted by itself and measuring a distance to an object based on a positional relationship between a light emitting position of the laser light and the image capturing position, and a distance measuring device. About the method.

[0002]

2. Description of the Related Art In recent years, with the development of CCD cameras and computer image processing, three-dimensional measurement using images has become popular. One of the three-dimensional measurements using a CCD camera and computer image processing is a light sectioning method. This light cutting method projects slit light on the object to be measured, as if cutting the object with a band of light,
The cross section is observed from another direction by the light. In addition, with the advent of lasers, very fine and high-luminance luminous fluxes can be obtained. Therefore, three-dimensional measurement by the light-section method can perform high-speed, high-precision measurement even for an object having a free-form surface. It has become.

[0003]

In the light cutting method, reflected light of the slit light on the surface of the object is imaged by a CCD camera provided in the self, and the direction of the emitted slit light and the light source The distance between itself and the object is measured from the position of the camera and the position of the CCD camera. Therefore, it is desirable that the reflected light intensity of the slit light captured by the CCD camera is constant.

By the way, the intensity of the reflected light varies depending on the distance to the object and the reflection characteristics of the surface of the object, even if the intensity of the slit light emitted by itself is constant. The light section method requires that the slit light be continuously imaged by a CCD camera due to its measurement principle. Normally, in three-dimensional measurement using the light section method, since the approximate distance to the object and the state of the surface of the object to be measured are known to some extent, the emission intensity of the slit light and the CCD camera during calibration before measurement are measured. In general, measurement is performed by adjusting the dynamic range.

However, when detecting the floor surface and obstacles existing on the floor surface by applying the light section method as a visual sensor of an autonomous mobile robot or the like, the distance to the object to be measured and the reflection characteristics of the object surface are unknown. Therefore, it is not practical to adjust the emission intensity of the slit light and the dynamic range of the CCD camera in advance. Therefore, it is necessary to perform measurement using a laser beam having a predetermined light emission intensity with a dynamic range covering from weak light to strong light. However, there is a problem that the dynamic range of the camera cannot cover the distance depending on the distance to the object and the reflection characteristics of the object. In particular, the light-section method is for recognizing the shape of the object or measuring the distance in accordance with the state of the captured slit light, so if the slit light cannot be captured, the image cannot be captured due to the influence of the dynamic range, or There is a problem that it is impossible to judge whether an image cannot be captured behind a shadow of an object, and as a result, it is not possible to accurately recognize the object and measure the distance.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has a distance measurement using a light-section method which makes it possible to uniformly image the slit light by making the brightness distribution of the slit light to be imaged uniform. It is an object to provide an apparatus and a distance measuring method.

[0007]

According to the first aspect of the present invention, a reflected light of a laser beam emitted by the self is imaged, and a distance to an object to be measured is determined from a positional relationship between a light emitting position of the laser light and the imaging position. A distance measuring device for measuring, wherein the distance measuring device is a laser emitting means for emitting the laser light, and a beam diffusing means for diffusing the laser light emitted by the laser emitting means in one direction to slit light. An image acquisition unit that captures the reflected light of the slit light on the object surface; and a light intensity distribution of the slit light that is provided between the beam diffusing unit and the object in a beam diffusion direction of the slit light. Light intensity distribution adjusting means.

The invention according to claim 2 is characterized in that the light intensity distribution adjusting means makes an intensity distribution determined based on the reflection characteristics of the object.

According to a third aspect of the present invention, the light intensity distribution adjusting means changes the light intensity distribution by changing the transmittance of the laser light according to an external control signal.

According to a fourth aspect of the present invention, there is provided a distance measuring method for imaging a reflected light of a slit light emitted by the self, and measuring a distance to an object from a positional relationship between a light emitting position of the slit light and the imaged position. In the distance measuring method, the laser light emitted from itself is diffused in one direction to form slit light, which is irradiated onto an object to be measured, and the luminance distribution of the reflected light of the slit light on the imaged object surface is uniform. The measurement is performed by adjusting the light intensity distribution of the slit light in the beam diffusion direction of the slit light to be irradiated.

According to a fifth aspect of the present invention, in the distance measuring method, a slit light having an intensity distribution determined based on a reflection characteristic of the object is irradiated.

According to a sixth aspect of the present invention, in the distance measuring method, the intensity distribution of the slit light to be irradiated is changed according to the luminance distribution of the reflected light of the slit light on the surface of the imaged object. I do.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a distance measuring device according to an embodiment of the present invention will be described with reference to the drawings. First, FIG.
A bipedal walking robot to which the distance measuring device is attached will be described with reference to FIG. In FIG. 3, reference numeral 1 denotes an autonomous bipedal walking robot (hereinafter simply referred to as a robot). Reference numeral 2 denotes an optical system device of the distance measuring device attached to the waist height of the robot 1. Symbol 3 is
The irradiation range of the laser beam irradiated by the distance measuring device 2,
The laser light is diffused by 60 ° in one direction, and is radiated to the floor 4 as slit light. Furthermore, the direction of the optical system device 2 is adjusted so that the slit light irradiates the floor surface in front of the robot 1 from the toe.

FIG. 1 is a block diagram showing the configuration of the embodiment. In this figure, reference numeral 11 denotes a laser light source that emits a laser beam for irradiating an object to be measured.
Reference numeral 12 denotes a short base line length camera having a short arrangement distance from the laser light source 11, and is constituted by a CCD camera. The short base line camera 12 has a feature that, since the base line length is short, the distance measurement accuracy is low and the front of the robot 1 can be seen over a wide distance range. Symbol 13 is
This is a long-baseline camera having a long arrangement distance from the laser light source 11, and is constituted by a CCD camera. This long baseline camera 1
No. 3 is characterized in that the distance measurement accuracy is high because the base line length is long, but the distance range over which the robot 1 can be seen is limited. Reference numeral 2 denotes an optical system device shown in FIG. 3 and includes a laser light source 11, a short base length camera 12, and a long base length camera 13. Reference numeral 14 denotes the laser light source 11
Is a light emission control unit that controls the laser light source by outputting a control signal for controlling the emission of laser light. Symbol 15
Is an image capturing unit provided with an image memory for capturing image signals output from two cameras.

Reference numeral 16 denotes a height estimating unit for estimating the height of the foreground object based on the image data captured by the image capturing unit 15. Reference numeral 17 denotes a moving path determining unit that determines the moving path of the robot 1 according to the state of the object estimated by the height estimating unit 16. Symbol 18 is
The landing position determination unit determines the landing position of the foot of the robot 1 from the path determined by the movement path determination unit 17 and the object height estimated by the height estimation unit 16. Sign 1
Reference numeral 9 denotes a leg control unit that controls the landing of the foot at the landing position determined by the landing position determination unit 18.

Next, the detailed configuration of the laser light source 11 shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration of the laser light source 11 shown in FIG. In FIG. 2, reference numeral 21 denotes a laser emitting unit that emits laser light. Reference numeral 22 denotes a condensing lens that condenses the laser light emitted from the laser light emitting unit 21 into a thin beam. Reference numeral 23 denotes a diffraction grating that divides the laser beam formed into a narrow beam by the condenser lens 22 into a plurality of beams, and divides the beam in a direction perpendicular to the plane of FIG. Reference numeral 24 denotes a beam diffusion lens composed of a cylindrical lens or the like, which generates a slit light by diffusing a laser light beam in one direction. Each of the plurality of beams is formed by the beam diffusion lens 24.
The diffusion angle should be 60 °. Reference numeral 25 denotes an intensity adjustment filter for adjusting the light intensity of the slit light.

In FIG. 2, when the positional relationship of the floor surface is shown, the straight line indicated by reference numeral 4 is the floor surface, and the point indicated by reference numeral A is the position of the toe of the robot 1. FIG. 5 is a schematic diagram showing a state in which the optical system device 2 is attached to the waist of the robot 1 and emits laser light. In FIG. 5, reference numeral 11 denotes a laser light source. Reference numeral 3 indicates an irradiation range of the laser light emitted from the laser light source on the floor 4. Here, the beam is divided into five beams by the diffraction grating 23, and the five beams are diffused by 60 ° by the beam diffusion lens 24. These laser beams are applied to the floor surface 4 and the reflected light is imaged by the baseline camera 12 and the long baseline camera 13. In FIG. 5, the number of beams divided by the diffraction grating 23 is set to “5” for easy understanding of the drawing. However, in actuality, the angle B shown in FIG. 5 is 32 ° and the angle C is 1.6. °. Therefore, the number of beams is “21”.

Next, with reference to FIG. 6, a general reflection characteristic of the floor surface will be described. FIG. 6 is an explanatory diagram showing the reflection characteristics of the floor surface. In general, the reflection characteristic of a surface has the highest intensity of the regular reflection component even if it is not a mirror surface unless the surface has perfect diffuse reflection characteristics. In the optical system device 2 attached to the position of the waist of the robot 1, the light emitting point and the observation point are almost the same. Therefore, when the reflected light at the reflection point 1 is received at the observation point, the regular reflection component is received. On the other hand, the specular reflection component at the reflection point 2 does not return to the observation point, and similarly, the specular reflection component at the reflection point 3 does not return to the observation point. Further, the angles D and E formed between the reflection direction of the specular reflection component at the reflection points 2 and 3 and the observation point direction increase as the distance from the observation point increases. The received light intensity of the reflected light becomes weaker as the angle between the reflection direction of the specular reflection component and the observation point direction becomes larger. Also, even if the emission intensity at the emission point is constant,
Since the intensity decreases in inverse proportion to the square of the distance, the light reaching the reflection point decreases as the distance from the light-emitting point to the reflection point increases. Therefore, the reflected light is reflected from the CC placed at the observation point.
When imaging with a D camera, there is a problem that it is difficult to observe a distant laser beam.

That is, as shown in FIG. 6, when the floor surface is irradiated with a laser beam and the reflected light is to be imaged,
Assuming that the reflection light at the reflection point 3 is “1”, the reflection light at the reflection point 1 is about “10”, which is a ten-fold difference. When this difference in light intensity is imaged in one dynamic range and quantized for digital processing is performed, in normal digital processing, since the number of quantizations is fixed, a small change in luminance is detected. Becomes difficult.

Based on the reflection characteristics of the floor surface, the intensity adjustment filter 2 controls the reflected light of the slit light to be imaged to have a constant received light intensity regardless of the position of the floor surface.
5 FIG. 4 shows the transmittance characteristics of the intensity adjustment filter 25. In FIG. 4, the y-axis is the transmittance in the wavelength range of the laser light emitted from the laser emitting unit 21. The x-axis is 0 ° in the direction perpendicular to the floor from the light emitting point and 60 ° forward.
Is the maximum angle of elevation. As shown in FIG. 4, the intensity adjustment filter 25 has a transmittance of 100% at an elevation angle of 60 ° (a direction reaching the farthest point from the light emitting point) and an elevation angle of 0 °.
Is 8%. Further, between 0 ° and 60 °, the transmittance is set so that the received light intensity at the observation point becomes constant in proportion to the change in the reflection characteristic of the floor surface and the change in the distance to the floor surface. In particular, the transmittance is lowered near the elevation angle of 0 ° in order to receive the specular reflection component. By attaching such a filter to the laser emitting unit 21,
Since the dynamic range of the CCD camera at the observation point can be small, it is possible to easily measure the distance from near to far.

FIG. 7 shows the configuration of the intensity adjusting filter 25. FIG. 7 is a view of the intensity adjustment filter 25 shown in FIG. In FIG. 7, reference numeral 3 is divided into five beams by the diffraction grating 23,
Further, a beam irradiation range of the obtained slit light diffused by the beam diffusion lens 24 is shown. The intensity adjustment filter 25 is located at the lower end of all beam irradiation ranges 3 (elevation angle 0).
) Is 8%, and the transmittance of the laser light at the upper end (60 ° elevation) is 100%. Then, between the lower end and the upper end, the transmittance changes so as to satisfy the transmittance characteristics shown in FIG. However, there is no change in transmittance in the horizontal direction (horizontal direction) on the paper surface of FIG. That is, the intensity adjustment filter 25 is configured such that the transmittance at the bottom is low, and the transmittance is increased toward the top.

When the light transmitted through the intensity adjusting filter 25 shown in FIG. 7 and reflected on the floor surface is imaged by the short base length camera 12 and the long base length camera 13, one slit light can be picked up with uniform brightness. Can be. This makes it possible to narrow the dynamic range for imaging the slit light, and as a result, it is possible to detect a small change in luminance.

The intensity adjustment filter 25 may use a liquid crystal filter to change the transmittance in each direction based on an external control signal. When a liquid crystal filter is used, the transmittance can be changed based on the control signal. Therefore, when the optical system device 2 is calibrated, the slit light illuminated on the floor surface is scanned by the short baseline length camera 1.
2 and the long baseline camera 13, and based on the imaging state, it is possible to adjust the transmittance so that the luminance distribution of the slit light becomes uniform, and to adjust the light emission intensity. In this case, it is not necessary to know the reflection characteristics of the floor surface in advance, and the distance can be measured even in an unknown environment.

Further, when the intensity adjustment filter 25 using a liquid crystal filter is used, the transmittance can be changed according to the reflection characteristics of the obstacle and the distance to the obstacle, so that the obstacle recognition processing is performed. It can be made easier.

As described above, since the brightness distribution of the reflected light is made uniform, it is possible to avoid a situation in which the dynamic range of the camera cannot be covered, and it is possible to accurately perform object recognition and distance measurement. Become.

[0026]

As described above, according to the first and fourth aspects of the present invention, the reflected light of the self-generated slit light is imaged, and the object is determined based on the positional relationship between the slit light emission position and the imaging position. When measuring the distance to, the laser light emitted by itself is diffused in one direction to form slit light, which is illuminated on the object to be measured, and the brightness distribution of the reflected light of the slit light on the imaged object surface is Since the light intensity distribution of the slit light is adjusted in the beam diffusion direction of the irradiated slit light so as to be uniform, the brightness distribution of the slit light to be imaged becomes uniform and the slit light is reliably imaged. The effect that it can be obtained is obtained. As a result, the distance accuracy can be improved, and the distance measurement process can be simplified.

According to the second and fifth aspects of the present invention, the slit light having the intensity distribution determined based on the reflection characteristics of the object to be measured is irradiated, so that the reflected light to be imaged is emitted. Since the brightness distribution can be reliably made uniform, an effect is obtained that the measurement can be performed even if the dynamic range of the imaging camera is not wide.

According to the third and sixth aspects of the invention, the intensity distribution of the slit light to be applied is changed according to the luminance distribution of the reflected light of the slit light on the surface of the imaged object. The effect is obtained that even if the object is unknown, the luminance distribution of the reflected light can be surely made uniform.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a laser light source 11 shown in FIG.

FIG. 3 is an explanatory diagram showing an appearance of the bipedal walking robot 1.

FIG. 4 is an explanatory diagram showing transmittance characteristics of the intensity adjustment filter 25 shown in FIG.

FIG. 5 is a schematic view showing a state where laser light is emitted from the optical system device 2.

FIG. 6 is an explanatory diagram showing reflection characteristics of a floor surface 4;

FIG. 7 is a view of the intensity adjustment filter 25 shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Robot, 2 ... Optical system apparatus, 3 ... Laser irradiation range, 4 ... Floor surface, 11 ... Laser light source, 12 ... Short baseline camera, 13 ... Long Baseline length camera, 14: Light emission control unit, 15: Image capture unit, 16: Height estimation unit, 17: Moving route determination unit, 18: Landing position determination unit, 19 ...・ Leg control unit, 21 ・ ・ ・ Laser emitting unit, 22 ・ ・ ・ Condenser lens, 23 ・ ・ ・ Diffraction grating, 24 ・ ・ ・ Beam diffusion lens, 25 ・ ・ ・ Intensity adjustment filter.

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2F065 AA06 AA24 AA51 CC00 EE04 FF01 FF02 FF09 GG04 GG08 HH05 HH06 JJ03 JJ05 JJ26 LL04 LL08 LL25 LL42 NN02 NN08 NN17 NN20 PP25 QQ03 FA13 DA03 FA03 DA03 FA08 AA05 AD05 AD07 BA04 BA34 BB02 BB07 CA03 EA04

Claims (6)

[Claims] 1. A distance measuring device which captures reflected light of laser light emitted by itself and measures a distance to an object to be measured from a positional relationship between a light emitting position of the laser light and an imaging position, wherein the distance measuring device A laser light emitting unit that emits the laser light, a beam diffusing unit that diffuses the laser light emitted by the laser light emitting unit in one direction into slit light, and captures reflected light of the slit light on the object surface. Image acquisition means, and light intensity distribution adjustment means provided between the beam diffusion means and the object, for adjusting the light intensity distribution of the slit light in the beam diffusion direction of the slit light. And a distance measuring device. 2. The distance measuring apparatus according to claim 1, wherein the light intensity distribution adjusting means sets an intensity distribution determined based on a reflection characteristic of the object. 3. The distance measuring apparatus according to claim 1, wherein the light intensity distribution adjusting means changes the light intensity distribution by changing a transmittance of the laser light according to an external control signal. apparatus. 4. A distance measuring method for imaging a reflected light of a slit light emitted by the self, and measuring a distance to an object from a positional relationship between a light emitting position of the slit light and an imaging position, wherein the distance measuring method comprises: The laser light emitted by itself is diffused in one direction to form slit light, which is illuminated on the object to be measured, and illuminated so that the luminance distribution of the reflected light of the slit light on the imaged object surface becomes uniform. A distance measuring method, wherein the measurement is performed by adjusting the light intensity distribution of the slit light in the beam diffusion direction of the slit light. 5. The distance measuring method according to claim 4, wherein the distance measuring method irradiates a slit light having an intensity distribution determined based on a reflection characteristic of the object. 6. The distance measuring method according to claim 4, wherein the intensity distribution of the illuminating slit light is changed according to the luminance distribution of the reflected light of the slit light on the surface of the imaged object. Distance measurement method.