JPS5932071A - Object detector for mobile machine - Google Patents

Abstract

PURPOSE:To decide the presence or absence of an obstacle and to obtain accurately the 3-dimensional position of the obstacle, by attaching rotatably a light source outside a region within a picture angle and on a circumference of an axis same as the axis connecting a lens and the center of a photodetecting element in order to set a search region and detecting the reflected light. CONSTITUTION:The line connecting a photoelectric element 3 and the center of a lens 2 is defined as an axis Z, and a point O distant from the element 3 by a distance l2 is defined as an original point. A laser light source 4 moves round on the circumference of a radius l1 centering on the point O and on an XY surface, and the beam passes through a point P. The area of a cone PCD having an apex P is defined as a search region excepting the bottom surface. When an obstacle 6 exists, the reflected light passes through the lens 2 and is detected by the element 3. The point P corresponds to the center of the element 3, and the circumference of a circle CD corresponds to the outer circumference of the element 3. Such a device is mounted and shifted, and the 3- dimensional position of the obstacle 6 within the search region is calculated from various factors shown in the figure. At the same time, the level difference of a road is also detected. Thus it is possible to obtain a detector which contains no mirror nor blind sector and facilitates easy matching of optical axes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an object detection device for a mobile machine, which is used when a mobile machine such as a mobile robot detects an obstacle or a step on a road surface during the movement process. It is something.

Ideally, a mobile robot or the like would use its own visual system to reliably recognize large and small obstacles, differences in ground, etc., and move only within a safe area.

Obstacle detection methods can be broadly divided into passive methods and active methods.As for passive methods, for example, obstacles are detected by taking in external information using an ITV camera, etc. There is a method.This method is sensitive to the shape of outside light and often involves complex pattern recognition work.On the other hand, active methods include ultrasonic!!1 measurement method and infrared light projection. The biggest advantage of this method is that it can freely create and oscillate or project signals that cannot exist in the external environment.However, ultrasonic measurement methods In principle, it is suitable for determining the presence or absence of obstacles and their average position, but is unsuitable for detecting their shape.Also, in the method of projecting infrared rays, etc., the beam diameter is narrowed and scanned. If you do this, you can capture the location and shape of the obstacle quite clearly, but it takes 111 seconds to scan.
It takes time and the signal processing requires mtlt. For these reasons, it is desired to develop an object detection device that can easily and reliably detect the presence or absence of an object to be detected and its three-dimensional position. This newly developed object detection device can optically easily and reliably determine the presence or absence of an object to be detected and its three-dimensional position. However, it is not always easy to align the optical axes, and the presence of a mirror support that changes the optical path of the light from the light source to form and cover the projected light may cause the object to be detected. There are still points that need to be improved in terms of configuring a dead zone that cannot be detected.

This invention was made in view of the above circumstances.C1 The presence or absence of an object to be detected and its three-dimensional position can be detected easily and reliably, and in particular, optical axis alignment is easy,
Moreover, it is intended to provide an object detection device for a mobile machine that does not have a dead zone.

Corresponding to this purpose, a moving area object detection device of the present invention includes an optical system, a light receiving element positioned at the focal point of the optical system, a light source, a power source for the light source, and a light intensity modulation circuit. The light source, the power source for the light source, and the light intensity modulation circuit are configured to rotate around the central axis of the optical system, and the area within both corners determined by the size of the light receiving element and the 1 to detect the object to be detected.
? It is characterized by having achieved one thing.

Hereinafter, details of the present invention will be explained with reference to the drawings showing one embodiment.

The principle 4ri of the object detection device 1 for a mobile machine of the present invention
As shown in FIGS. 1 and 2, the optical system includes an optical system such as a lens 2, a light receiving element 3 located at the focal point of the optical system such as the lens 2, and a light source 4.

The area within the viewing angle 5 is determined by the size of the light receiving element 3.

Here, the area within the angle of view is defined as the 38th area within which the detected object 6 is irradiated with light.
The reflected light from 01' enters the light receiving element 3 through the lens 2.
Tj, that is, an area where the light receiving element 3 can optically detect the object to be detected 6. On the other hand, when the light source 4 is moved along an arbitrary closed curve 10, the beam 7 forms an envelope surface 8 (indicated by diagonal lines). In other words,? ! If the object 6 to be detected is on this envelope surface 8, the object 6 to be detected will receive the illumination m of the beam 7 in accordance with the moving period of the light source 4. Therefore, the search area -11 is determined by the two-cornered inner region 5 of n0 and the above-mentioned envelope surface.
a (the surface excluding the base of a cone with diameter ΔB and apex P), 11b (surface excluding the base of a cone with diameter CD and apex P) are determined, and this search area 11a,
If the detected object 6 exists in 11b, the detected object 6
Since the beam 7 is irradiated and the light receiving element 3 can receive the reflected light of the beam 7, the object to be detected 6 can be detected.

First, we will introduce the area 5 within the field of view formed by the light receiving element 3 with four functions and the lens 2 as a two-dimensional position detecting element.
Consider how to illuminate the area. When projecting light into the field of view area 5 from an arbitrary point, the inspection area is the projection a as shown in Figure 1.
In the case of , the decomposition A corresponds, and in the case of light projection, the half line B corresponds to each other. Therefore, when the light projection position is moved one-dimensionally, the inspection area becomes a plane. Note that the inspection area is defined as an area where, if there is an object in that area, a part of the reflected light from the sub-bottom 1 that hits the object can enter the light receiving element 3. Here, as a simple example, the light projection position, that is, the light source 4
Consider the case where the lens does not move along a circle whose center coincides with the axis of the lens system. There are four possible light projection methods as shown in FIG. Here, the shaded area is a usable area of the light receiving element 3, and the curved area of the shaded area is an area in which the correspondence with the inspection area is 2=1. Since the intensity of reflected light from an object is proportional to the square of the distance nt, it is essentially difficult to detect and cover a distant object. In the case of J, ta, Φ), the position detection element deteriorates to the 1iIi end as it approaches /-■. On the other hand, what are the advantages of case (■)? 1) The efficiency of the light receiving element surface is the highest. (2) The position detection resolution is the best.
(3) Only the reflected light from the object in the finite inspection area enters the light receiving element, so the presence or absence of an object in the limited area can be turned on.
You can check it offline. Therefore, from now on, we will adopt the type of light projection method.

4 and 5 show an object detection system for mobile machines according to an embodiment of the present invention.
In the figure, 1 is a moving FJJ machine object detection device, and the moving machine object detection device 1 is equipped with a lens 2.

Lens 2 is a condensing lens with a focal length f. A light receiving element 3 functioning as a position detecting element is placed at the focal point of the lens 2. A light source 4 is mounted on the rotating ring 2 outside the optical axis of the lens 2.
It is attached and arranged at 1. The light source 4 is oriented in a direction in which its projected light intersects the optical axis at point P. The rotating ring 21 has an annular shape and is rotatably supported by a support ring 23 via a bearing 22, and rotates 11 U around the optical axis.The rotation of the support ring 23 causes the light source 4 to rotate around the optical axis. do. The rotation angles of the rotation ring 21 and the light source 4 are detected by a rotation angle meter 24 attached to the support ring 23. Rotating ring 21
A gear 24 is installed around the
A pinion 26 is engaged with the pinion 26. Pinion 26 is driven by motor 27. A power source 31 and a light intensity modulation circuit 32 for operating the light source 4 are also attached to the rotating ring 21. The above lens 2, light receiving element 3, support ring 23, and motor 27 are fixedly supported by a frame 28. It should be noted that as the light source 4, a ray light with almost no scattering etc. is suitable for E1, and hereinafter a laser will be used as the light source. In this case, it is better to oscillate the laser beam in a pulsed manner in order to clearly distinguish between the reflected light from the laser beam and the external light, unless the laser beam is used in a place where there is no external light. Note that some types of semiconductor lasers are capable of oscillating pulses of several Mt-1z, and even if the rotational speed of the rotating ring 21 is increased to a physically possible OL range, the decrease in the decomposition OL can be ignored.

In such a 41 configuration, the light source 4 rotates at a constant rotation speed.
The beam from the lens is projected into an area 5 within the field of view of the lens system, as shown in FIG. The search area for detecting the object to be detected is the portion of a circle 11 whose apex is the point P and whose diameter is CD, excluding the bottom surface.

- When the angle of the light projection position is O, then X --(ゝ fist cos e
(1) O V = -r -3ill e (
2) 0 z, = (r −1, −r ・(f −12> )/
<f −tanβ−r) (3) where r. =r (1,-(f-12) bow old 1β)/
(f·ta IIβ-rl (4) From the above equation, the detected position IN of the detected object 6 can be determined.

This moving machine object detection wave V! 7, 8, and 9 show how the robot 11 is mounted on the mobile robot 1 to detect objects to be detected or unevenness on the road surface.

First, if there is no unevenness on the road surface, use the previous formula and the 10th
Obstacles 6 are detected according to the process shown in the flowchart of the figure. When the mobile robot approaches the obstacle 6 but is outside the search area 11, even if the laser beam hits the obstacle 6, the reflected light does not enter the light receiving element 3, but the robot moves forward and approaches the obstacle 6. When one part touches a part of the surface of the conical PCD in the search area 11 except for the bottom surface, two parts of the laser reflected light are received by the light receiving element 3 and contain a signal of the same frequency as the emitted light. The output is 19. Further, in order to obtain information on the detected position, the output signal may be converted to rSe and the above-mentioned calculation may be performed.

Next, as shown in FIG. 8, a part of the circle at the bottom of the circle tlt is set so as to intersect with the ground. In this case, when the light source 4 rotates once, the reflected light reaches the light receiving element 3 at the intersection of the cone and the road surface, so if the process shown in the flowchart in Figure 10 is used, the road surface will be regarded as an obstacle. I end up.

On the other hand, if there is no unevenness, the O value of the y-coordinate of the intersection is not J: but is -Y. (See Figure 7). This can be used to investigate road surface irregularities.

However, the strip f1 with no unevenness at e, < 9 < θ2 (intersection) is y, = YQ (5) Rewriting, r = 13/(1 + (Δsin e/Y) ) (6
) Δ−r tanβ, B=1. −(f −12) tan β Therefore, O
If (r, e) deviates significantly from the relationship in equation (6) at <θ<02, it is assumed that there is a step. Also, as shown in FIG. 8, '11J: Even when there is a slope instead of a step, the relationship gradually deviates from the equation (6), but it can be distinguished from a step by the rate of change of yO.

As is clear from the above description, the present invention provides an object detection device that can easily and reliably detect the presence or absence of an object to be detected and its three-dimensional position.

In particular, this object position detection device for a moving machine can emit light directly from the light source and does not require a mirror for changing the optical path, making it extremely easy to align the optical axes.
Since there is no additional support device to support each mirror, no dead zone is formed on the light receiving element (and accurate object detection is possible).

[Brief explanation of drawings]

a'! Figure 1 is an explanatory diagram showing the relationship between the area within the angle of view and the inspection area, and Figure 2 is a perspective view μ showing the relationship between the area within the angle of view and the inspection area.
3 is an explanatory diagram showing a light projection method, FIG. 4 is an explanatory side view of an object detection device for a mobile machine according to an embodiment of the present invention, and FIG. 5 is a front view of the object detection device for a mobile machine. 6 is a perspective explanatory view showing the area within the field of view and the search area formed by the object detection device for a mobile machine; FIG. 7 is a 'TJ' explanatory view showing the state of obstacle detection; The figure is an explanatory diagram showing the state of level difference detection, Fig. 9 is an explanatory diagram showing the state of detecting a slope on the ground, and Fig. 10 is an explanatory diagram showing the procedure of the detection operation.
This is a flowchart. '1...Movement v1 Mechanical object detection 1A''F2 2...
・Lens 3... Light receiving element 4... Light source 5...
・Region within both corners 6...Object to be detected 7...Beam
8... Envelope surface 21... Rotating ring 22... Bearing 23... Support 1 temple 1π 24... Rotation angle reduction 57 Cantilever π “Wish Power 1407!11
No. 2 Name of the invention (!J, Object detection device for mobile machinery I No. 1 (
+14) Name Makoto Ishizaka, Director, Agency of Industrial Science and Technology -5
11 clauses of the +ili and il instructions Voluntary Betsugi Street 8, Attachment HIH4ri [l record] Amendment to the column of detailed explanation of the invention in the attached attached specification (1) 1 in the 3rd line of page 8 of the specification -Support ring 2 @" is corrected to "1 rotation ring 21". (2> light $111111m 8 n 6th row empty ff
! 7 row 1. : [#1 car 24J is replaced with "tooth width 25".
J and MTI. (3) In the specification, page 11, line 3, "Fig. 1-7" has been corrected to "Fig. '' has been revised as ``Figure 9''.

Claims (1)

[Claims] An optical system, a light receiving element located at a focal position n of the optical system, a light source, a power source for the light source, and a light intensity modulation circuit (1&E,
The light source, the power source for the light source, and the light intensity modulation circuit are rotated around the central axis of the optical system (M configuration), and the light source and the inner corner area determined by the size of the light receiving element are A search area is defined by the phase n-body with the envelope surface of the beam when it rotates around the central axis of the optical system, and the beam is reflected from an object to be detected existing within the search area. Object detection device U for a mobile machine, characterized in that the object to be detected is detected by receiving light with the light receiving element.