JPH03282312A - Method and instrument for measuring separation distance of mobile object - Google Patents

Abstract

PURPOSE:To measure the separation distance between mobile objects by regressively reflecting light emitted from a following mobile object in the preceding mobile object and forming an image on the light receiving surface of the following mobile object with the reflected light, and measuring the size of the image. CONSTITUTION:A detector 10 consists of a light projection part 11 and a light receiving part 12. The projection part 11 emits the light forward, i.e. to the preceding mobile object 1. At the light receiving part 12, the light receiving surface 16 consisting of a photosensor array is arranged and in front of the light receiving surface, i.e. on the side of the preceding mobile object 1, a lens system 17 consisting principally of a light receiving lens is disposed. The light emitting from the projection part 11, therefore, irradiates regressive reflection points P1 and P2 and is regressively reflected by the surface. The regressively reflected light is made incident on the light receiving surface 16 through the lens system 17 to form two bright point images on the surface. The distance between those two bright points is measured by the light receiving surface 16, i.e. photosensor array to know the angle theta of the regressively reflected light from the relation shown by a specific expression, so the separation distance L1 between the following mobile object 2 and preceding mobile object 1 is measured.

Description

[Detailed Description of the Invention] [Technical Field Subject to the Invention] The present invention relates to measuring the separation distance between a preceding moving object and a moving object following this moving object when a plurality of moving objects are moving. It is particularly applicable to objects in which a leading moving object and a following moving object move independently or at variable speeds, or at a predetermined distance from each other, such as flying objects, flying objects, vehicles, or unmanned vehicles. It is something that will be done.

[Prior Art and its Problems] Conventionally, when a moving object such as an unmanned vehicle is preceded by a vehicle following a preceding vehicle, it goes without saying that it is necessary to prevent a collision between the two vehicles. In particular, vehicles that run on tracks mounted on the ceiling can travel at high speeds without the risk of colliding with people, and the speeds are increasing year by year.

For this reason, there is an increasing need to prevent a collision between a following vehicle and an unmanned vehicle traveling in front, and it is necessary to constantly detect the relative distance between the two vehicles while the vehicle is running energetically.

However, since increasing the speed depends on the extent to which the relative distance of the vehicle can be detected, a distance detector with higher performance is required.

Generally, as a distance measurement technique, as shown in FIG. The image is formed, and the distance L1 is determined by this image forming position.
There is a way to find out.

This method is a type of distance measurement by triangulation, and if the distance L2 between the light emitter 11 and the light receiver 12 is small, it is difficult to increase the distance. The angle θ between the two planes becomes infinitesimal, and even if the distance changes, the change in θ is extremely small, and very sophisticated equipment is required to accurately measure this. Therefore, increasing the distance between the light emitter 11 and the light receiver 12 alleviates the above problem, but on the other hand, it is extremely difficult to integrate the detector 10, and when using such a detector,
It is troublesome to align the tip of the shaft. Further, it is necessary to adjust the relative angle between the light projecting section 11 and the light receiving section 12, and there are other problems such as the alignment of the axes is delicate and difficult.

Furthermore, all of the above methods have the following common problems.

First, these methods are vulnerable to disturbance light noise.

In other words, when the light beam emitted from the light projector 11 hits the object to be measured, a bright spot is formed on the surface of the object, but the light from the bright spot is scattered light and is therefore weak (especially when measuring long distances). It will be affected by disturbance light noise.It is possible to use laser light to counteract this effect, but the output of laser light is naturally limited for safety reasons. In the conventional method, the detector 10 has extremely strong directivity.In other words, the moving object to be measured, such as an unmanned vehicle, is constantly receiving the light beam from the light projector. In other words, the object to be measured needs to be on the optical axis of the detector 10.For example, in the case of a moving object running on the track 3, if the trajectory is curved, the unmanned vehicle to be measured will be exposed to the projected light beam. As a result, the distance between the preceding moving object 1 and the following moving object 2 cannot be measured.

However, in this case, this drawback can be solved by scanning the projected beam from the light projecting section 11 in a movable manner;
becomes more complex and larger, and requires highly accurate optical components.

Generally, the method of scanning the projected light beam is extremely expensive;
Its uses will also be limited.

Further, as shown in FIG. 11, when the trajectory 3 is curved and there is an object 20 such as a pillar in front of the moving object, the object is irradiated with the projection beam from the light projection section 11. Since the detector 10 detects the reflected light from this, the reflected light clearly becomes an erroneous signal.

That is, the detector IO will respond to everything that falls within its limits and will each time issue a distance signal depending on the projected beam.

[Object of the Invention] In view of these conventional problems, the present invention is capable of accurately and reliably measuring even when the distance between a moving object in front and a moving object following it is relatively long. The purpose is to provide a compact and inexpensive measuring method and device that can perform stable distance measurements even when the object to be measured is slightly off the optical axis of the detector without causing erroneous measurements due to objects other than the detector. That is.

[Summary of the Invention] This invention emits light toward a preceding moving object from another moving object following it, and the preceding moving object reflects the light back. This retroreflected light is imaged on the light-receiving surface of the following moving body via a lens system. Then, by measuring the size of the image of the formed light, the distance between the two moving bodies is measured.

[Embodiment] A case where an embodiment of the present invention is applied to an unmanned vehicle will be described below with reference to the drawings.

That is, in FIG. 1, a pair of moving bodies 1. For example, unmanned vehicles move at variable speeds. Then, on the rear wall surface of the preceding moving body 1, there are a plurality of retroreflection points P, that is, Pl, P2,
In order to obtain P3 . In this embodiment, the retroreflection means is composed of two retroreflection plates 7a and 7b, which are mounted at a predetermined distance from each other. On the other hand, a detector 10 is attached to the front wall surface of a moving body 2 following the preceding moving body 1.

It should be noted that if the retroreflection points P1, P2, P3, .

In addition, in FIG. 2, the detector IO includes a light emitter 11 and a light receiver 1.
Consisting of 2. The light projector 11 then emits light toward the front, that is, the preceding moving object l. This light does not need to be converged into a narrow beam like the light from the light emitting part of a well-known coaxial reflective photoelectric switch; for example, the light becomes weaker by about 50% at a position offset by ±IO degrees from the optical axis. It may have the directivity of Further, the light receiving section 12 includes a light receiving surface 16 consisting of an optical sensor array called a line sensor, and a lens system 17 mainly including a light receiving lens in front of this light receiving surface, that is, on the side of the preceding moving body 1.

Therefore, the light emitted from the light projector 11 is irradiated onto the retroreflection point P, and is retroreflected on this surface. This retroreflected light then enters the light receiving surface 16 via the lens system 17 and forms two bright spot images on the surface. Therefore, if the distance between these two bright spots is measured by the light-receiving surface 16, that is, the optical sensor array, then from the following relationship, the angle θ formed by the retroreflected light is
Since this is known, the distance L1 between the following moving body 2 and the preceding moving body 1 is measured. Here, the angle θ formed by the retroreflection light is Ll, which is the separation distance between the preceding moving body 1 and the following moving body 2, and L2, which is the distance between the retroreflection points P1.22, that is, the distance between the outer ends of both retroreflection plates. , when the distance between the bright spots measured by the light receiving surface 16, that is, the optical sensor array is L3, and the distance between the lens system 11 and the light receiving surface 16 is L4, the following equation is obtained.

Note that this method is essentially conventional triangulation.

According to experiments, a light emitting diode that emits near-infrared light was used as the light projector 11, and a 512-element 25μ light-receiving surface 16 was used.
Using Pitzchi's CCD line sensor and its light receiving surface 1
A lens with a diameter of 30 mm and a focal length of 30 mm is placed at the front part L4 = 30 mm of the lens 6, and two retroreflectors 7a and 7b are placed at a point L1 = 10 m from the light projector 11.
2=300 mm, a sufficient optical signal was obtained from the light receiving surface 16, that is, the sensor array.

At this time, Ll, L2, and L4 are L1=10m=10'm
m,, L2=300mm, so from equation (1), L3=
It becomes 0.9mm.

FIG. 3 shows the output of the detection unit IO, that is, the light-receiving surface 16, and in this figure, the distance from the first point p1 to the second point p2 is the distance L3 between bright lines on the light-receiving surface I6.

Note that when the trajectory 3 is curved and there is another object, such as a pillar 20, in front of the moving object, as shown in FIG. Since the light is not reflected back depending on the object, the light does not substantially reach the light receiving section 12.

If the trajectory 3 is straight, the two bright spots on the light receiving surface 16 will be located near the optical axis with a distance of L3, but if the trajectory 3 is curved, Two bright spots will exist at a distance from the optical axis O depending on the degree of illumination.

In FIG. 4, the light entering the light receiving surface 16 is detected in the detection zone Zl.
must be inside. Therefore, the presence of two reflecting plates 7a17b in the detection zone Zl is a condition for detection. It is therefore necessary that the trajectory 3 lies within the detectable trajectory zone z2.

If the track 3 is curved in only one direction, for example in a 0-shape, a retroreflector 7 is used as shown in FIG. 4(a).
It is effective to provide a and 7b asymmetrically with respect to the optical axis. The detection zone z2 of the orbit at this time is the fifth
It will look like the figure.

On the other hand, if the trajectory 3 is curved to the left or right, like a figure 8 shape, for example, the retroreflectors 7a and 7b may be provided symmetrically with respect to the optical axis 0, as shown in FIG. 4(b). It is valid. The detection zone of the trajectory at this time is as shown in FIG. In addition, when two retroreflectors 7 are used, long-distance measurement is possible by widening the interval between the retroreflection points, but when the measurement target approaches, the distance between the bright spots on the light receiving surface 16 increases. becomes wider, and finally the bright spot reaches the light receiving surface 16
In other words, there is a risk that it may protrude outside the line sensor.

This state is the same as when the object to be measured is extremely far away and there is no signal, and not only is it virtually impossible to measure, but it is also extremely dangerous. To deal with this, one of the retroreflection plates 7a is provided on the optical axis, and when both moving bodies 1 and 2 come very close, one of the retroreflection plates 7a
What is necessary is to ensure that the bright spot caused by a is always present on the line sensor. Although this method makes the retroreflector 7a17b asymmetrical with respect to the optical axis, it is an effective means in the case of a zero-shaped trajectory, for example.

If the trajectory is curved to the left or right, such as in the case of a figure-8 shape, it is better to install the two retroreflectors 7a and 7b symmetrically with respect to the optical axis, so the above method is not appropriate. Therefore, a photoelectric switch or the like may be provided to detect the presence or absence of a moving object in front at a close distance, but the configuration would be a double track. Therefore, it is more effective to provide a third regressive reflector separately from the first and second regressive reflectors 7a and 7b. According to this method, it is possible to not only know the presence or absence of a moving object in front at a close distance, but also to know the distance. That is, as shown in FIG. 10(a), a third recurrent reflection point, that is, a recurrent reflection plate 7c is provided between the two recurrent reflection plates 7a and Tb. This third
The recurrent reflector is located near the optical axis of the light-receiving surface 16, in reality directly facing the optical axis of the lens system 17, that is, the light-receiver lens, and there are two recurrent reflectors 7a, ie, the first and second recurrent reflectors.
7b. It is desirable that these three retroreflectors have equal intervals.

When measuring a long distance, that is, when the preceding moving object 1 and the following moving object 2 are in a long-distance area that is shorter than a preset detection limit distance by a predetermined distance, the distance between the leading moving object 1 and the following moving object 2 on the light-receiving surface 16 is If the distance between the farthest light images, that is, the distance between the two outer bright spots among the three bright spots, is measured, it will be substantially the same as when there are two retroreflection points.

When the measurement target approaches further, the third retroreflector 7
Since C directly faces the light receiving section 12, the corresponding third bright spot on the light receiving surface 16 gradually becomes larger.

So, this time, the size of this bright spot, for example, the first point p
1 to the second point p2, actually the distance between both ends of the bright spot in the detection direction, that is, the size L3 of the light image itself.
Measure. Further preceding moving body 1 and following moving body 2
Assuming that the distance when the two moving bodies 1.2 approach and the size of the light image itself increases to a point equal to the light receiving surface 16, that is, the effective area L5 of the line sensor array is the approach limit distance, then both moving bodies 1.2 reach this approach limit. The state of the optical signal when the object is closer than the distance is completely different from the state of the optical signal when it is further away than the detection limit distance, so the presence or absence of a preceding moving object can be determined.

In other words, this measurement method can measure from a long-distance area Zf to a short-distance area Zn that is continuous with this long-distance area, and furthermore, the separation distance between the preceding moving object 1 and the following moving object 2 is a preset approach limit distance. , the distance can be measured when it is in a short range area Zn that is a predetermined distance away from it,
It can also determine when the object is closer than the close-range area of the parentheses. The state of the detected trailing orbit zone Z2 at this time is the seventh
It will look like the figure.

In order to further secure this detectable trajectory zone, a middle-range region Zm is provided between the long-range region Zf and the short-range region Zn so as to overlap both regions.

In this case, instead of measuring the outermost bright spot as in the case of the long-distance area Zf, the measurement is performed by measuring the recurrent reflection points adjacent to each other, that is, the first recurrent reflection plate 7a and the third recurrent reflection plate or The distance between the bright spots on the light receiving surface 16 is measured, which corresponds to the distance between the second regressive reflector 7b and the third regressive reflector 7C. In this measurement, the regression reflection point outside the rainfall amount is
It does not need to be within the detection zone; it is sufficient that two adjacent retroreflection points are within the detection zone. In this case, the detectable trajectory zone Z2 has a medium range area Zm added thereto as shown in FIG. 8, and the detection zone between the long range area Zf and the short range area Zn can be expanded. In this explanation, the case where there are three retroreflection points, that is, three retroreflection plates has been described, but if the number of retroreflection points is further increased, the distance between adjacent retroreflection points will be shortened, and the detection zone will be expanded accordingly.

Note that if measurement of the short distance area is not necessary, the measurement of the detection area may be performed only in the long distance area 2f and the middle distance area Zm as shown in FIG.

Furthermore, as shown in FIGS. 10(b) and 10(c), the retroreflector 7
By increasing , those areas are further subdivided. - Measurement target located at a long distance of the blade, that is, the preceding moving object 1
When the separation distance between the moving body 2 and the following moving body 2 is in the long distance region Zf, it is necessary to prevent strong disturbance light from entering the light receiving surface 16. In this case, by lighting the light source in pulses and extracting a signal corresponding to the pulse, malfunctions due to ambient light can be prevented.

Moreover, the plurality of retroreflection points provided on the preceding moving body l are determined by the ratio of the interval between the farthest apart retroreflection points to the interval between the adjacent retroreflection points, and the interval between the adjacent retroreflection points. and the size and ratio of one retroreflection point itself are set to be equal.

As a result, when the separation distance of the removable body is in the long-distance region 2f, the size of the light image on the light receiving surface 16 corresponds to the light image of the retroreflection point which is far away from each other, and from this state the removable object is moved again. When the bodies relatively approach and reach the middle distance region Zm, the size of the light image on the light receiving surface 16 corresponds to the light image of the adjacent retroreflection point, and from this state, the image of the moving body 1.2 relatively approaches and reaches the short distance area, the size of the light on the light receiving surface 16 corresponds to the image of the light of one retroreflection point, respectively.

In other words, when the separation distance between the removable bodies 1 and 2 is in the middle distance region, the recursion reflection point located on the outside is the detection surface 16.
The distance is measured by the retroreflection points that are adjacent to each other even if they deviate from the distance, and when the separation distance of the re-moving object 1.2 reaches the short distance area Zn and the number of retroreflection points is finally one. The distance is measured from the size of the image of light from one retroreflection point.

[Effects of the Invention] As described above, when at least two moving bodies move back and forth, the following moving body emits light to the preceding moving body, and this light is transmitted to the preceding moving body. The distance between the re-moving objects is measured by reflecting the light back and forming an image on the light-receiving surface of the following moving object using a lens system, and measuring the size of the image of the light on the light-receiving surface. Since the angle formed by the retroreflected light is large, it is possible to measure the distance from the following moving object to the preceding moving object over a long distance, and also when the re-moving object approaches extremely. It can be easily determined, and furthermore, it does not respond to anything other than the preceding moving object, and has the effect of ensuring reliable measurement even if the measurement target is slightly deviated from the optical axis of the light receiving section. In particular, when a moving object moves forward in a curve, even if there is another object such as a pillar in front of it, the distance between that object and the moving object is not measured. In other words, it is possible to skillfully improve points that cannot be measured using normal distance measurement technology.

On the other hand, it is not necessary to particularly enhance the directivity of the light from the following moving object as in the prior art, and even if the directivity is relatively wide, it is easy to measure. Therefore, it is less necessary to align the optical axes of the light emitting part and the light receiving part, and therefore the light emitting and receiving part can be easily integrated.

In particular, since the light-receiving surface detects retroreflected light, this method has the advantage of being less susceptible to disturbance light noise than methods that detect scattered light.

[Brief explanation of drawings]

Figures 1 to 11 show an embodiment of this invention.
Fig. 1 is a perspective view showing the running state of the moving body, Fig. 2 is a principle diagram showing the measurement principle in this invention, Fig. 3 is a waveform diagram showing the output of the detector, and Figs. 4 to 9 are moving objects. Fig. 10 is a plan view showing the arrangement of the retroreflector, and Fig. 11 is a plan view explaining the method of measuring the separation distance when the moving body is running. , 12th
The figure is an explanatory diagram showing a conventional distance measuring method. z2 ・ Zn ・ Zf φ Zm ・ Detectable orbit zone Near range area Long range area Middle range area Leading moving object Following moving object Trajectory Regression reflector, detector, light emitter, light receiver, light receiver, light receiving surface, lens system Retroreflection point/detection zone 2 Figure 3 Figure 4 Figure 1 Figure Clear Figure Figure Figure 10 /a'/C 0 e /D

Claims (26)

[Claims] (1) When there is a moving object following the preceding moving object, the following moving object emits light in front of it, and the light returns at multiple points at the rear of the preceding moving object. Reflect the light, form an image on the light-receiving surface of the following moving object via a lens system, and measure the size of the light image on the light-receiving surface from the first position to the second position. 1. A method for measuring separation distance of a moving object, characterized in that the distance from a following moving object to a preceding moving object is calculated by doing so. (2) The moving body according to claim 1, wherein the preceding moving body, the following moving body, and the succeeding moving body move along one predetermined line. Separation distance measurement method. (3) The separation of the moving bodies according to claim 1, characterized in that the light emitted from the following moving body is reflected back at two points separated from each other at the rear of the preceding moving body. Distance measurement method. (4) The light emitted from the following moving body is reflected back at three or more odd-numbered points spaced apart from each other at the rear of the preceding moving body. A method for measuring the distance between moving objects. (5) The movement according to claim 1, characterized in that the light emitted from the following moving body is reflected back at points spaced apart from each other by equal distances at the rear of the preceding moving body. How to measure distance between bodies. (6) The light emitted from the following moving body is reflected back at a point symmetrical about the optical axis of the light-receiving surface at the rear of the preceding moving body. Distance measurement method for moving objects described above. (7) The light emitted from the following moving body is reflected back at a point asymmetrical about the optical axis of the light receiving surface at the rear of the preceding moving body. Distance measurement method for moving objects described above. (8) The size of the light image formed on the light-receiving surface is measured from the first position to the second position in the detection direction of the light-receiving surface. A method for measuring the separation distance of a moving object according to scope 1. (9) The distance between the retroreflection points, the magnification of the lens system, and the size of the light image on the light-receiving surface are determined by the distance between the preceding moving object and the following moving object, which is the approach limit distance or the detection distance. 2. The method for measuring separation distance of a moving body according to claim 1, characterized in that a value at a critical distance is measured. (10) When the following moving object approaches the preceding moving object to a preset approach limit distance, the light emitted from the following moving object returns to the rear of the preceding moving object. When reflected, at least 1
2. The method for measuring the separation distance of a moving body according to claim 1, wherein the two reflection points are located near the optical axis of the light receiving surface. (11) When the preceding moving object and the following moving object are in a long-distance area that is shorter than a preset detection limit distance by a predetermined distance, the light that is farthest from each other on the light receiving surface The distance between the images of the preceding moving object and the following moving object are measured, and when the preceding moving object and the following moving object are in a preset approach limit distance and a near-range area that is a predetermined distance away from this distance, the light on the light receiving surface is measured. 2. A method for measuring a separation distance of a moving body according to claim 1, characterized in that the size of the image itself is measured. (12) When the preceding moving object and the following moving object are in a long-distance area that is shorter than a preset detection limit distance by a predetermined distance, the light that is farthest from each other on the light receiving surface a distance between images of the preceding moving object and the following moving object is shorter than the long distance area, and a preset approach limit distance between the preceding moving object and the following moving object; When in a medium-distance area between a short-distance area that is a predetermined distance away from the
2. The method for measuring the separation distance of a moving body according to claim 1, wherein the distance between adjacent light images on the light receiving surface is measured. (13) When the preceding moving object and the following moving object are in a long-distance area that is shorter than a preset detection limit distance by a predetermined distance, the light that is farthest from each other on the light receiving surface The distance between the images of the preceding moving object and the following moving object are measured, and when the preceding moving object and the following moving object are in a preset approach limit distance and a near-range area that is a predetermined distance away from this distance, the light on the light receiving surface is measured. The size of the image itself is measured, and when the preceding moving object and the following moving object are at an intermediate distance between the long distance area and the short distance area, the size of the image itself is measured. Claim 1, characterized in that the distance between adjacent light images is measured.
Method for measuring separation distance of moving objects as described in . (14) The movement according to claim 1, wherein the light emitted from the succeeding moving body toward the preceding moving body is reflected by a return reflection means at the preceding moving body. How to measure distance between bodies. (15) a plurality of retroreflection plates provided on a preceding moving body; provided on a moving body following the preceding moving body;
a light projecting section that emits light to the retroreflector; a light receiving section that has a light receiving surface that forms an image of the light emitted from the projecting section and reflected by the retroreflector; and a light receiving section that emits light on the light receiving surface. a detection unit that detects the length of the image from the first position to the second position; and a distance between the following moving body and the preceding moving body is calculated based on the output of this detection unit. A separation distance measuring device for a moving object, comprising a calculation section. (16) The moving body separation distance measuring device according to claim 15, wherein the preceding moving body and the following moving body move along one predetermined line. (17) The distance measuring device for a moving body according to claim 15, wherein the regression reflector is disposed at two points separated from each other at the rear of the preceding moving body. (18) The separation distance of the moving body according to claim 15, characterized in that the retroreflector is disposed at three or more odd-numbered points spaced apart from each other at the rear of the preceding moving body. Measuring device. (19) The separation distance measuring device for a moving object according to claim 15, wherein the retroreflection plates are disposed at the rear of the preceding moving object at equal distances from each other. (20) The separation of the moving body according to claim 15, wherein the retroreflector is disposed at a point symmetrical about the optical axis of the light-receiving surface at the rear of the preceding moving body. Distance measuring device. (21) The separation of the moving bodies according to claim 15, wherein the retroreflector is disposed at a point symmetrical about the optical axis of the light-receiving surface at the rear of the preceding moving body. Distance measuring device. (22) The above-mentioned retroreflector plate has the following effects on the above-mentioned preceding moving body:
Claims characterized in that at least one retroreflector is disposed in the vicinity of the optical axis of the light-receiving surface when the following moving object approaches a preset approach limit distance. 16. The moving body separation distance measuring device according to item 15. (23) The size of the light-receiving surface is set to a size that will block the light from the regression reflector when the distance between the preceding moving object and the following moving object is within the detection limit distance. A separation distance measuring device for a moving body according to claim 15, characterized in that: (24) The size of the light receiving surface is such that when the separation distance between the preceding moving object and the following moving object is within a preset approach limit distance or detection limit distance, the light from the retroreflector is 16. The apparatus for measuring the separation distance of a moving body according to claim 15, wherein the apparatus is set to a size that allows an image to be imaged. (25) Among the above-mentioned retroreflectors, the ratio of the distance between the farthest apart retroreflectors and the distance between the outer ends of the retroreflectors adjacent to each other, and 16. The separation distance measuring device for a moving body according to claim 15, wherein the distance between the outer ends of adjacent retroreflectors is equal to the size of one retroreflector itself. (26) A plurality of movable bodies, a plurality of retroreflection plates provided at the rear of each of these movable bodies, and a plurality of retroreflection plates provided at the front portion of each of the movable bodies, and radiating light to the retroreflection plates. a light projecting section; a light receiving section having a light receiving surface that forms an image of the light emitted from the light projecting section and reflected by the retroreflector; A detecting section detects the length to the second position, and based on the output of this detecting section, the distance between the following moving object and the preceding moving object is detected. A separation distance measuring device for a moving object, comprising: a calculation unit that calculates a separation distance from a moving object to the preceding moving object.