JPH03217909A - Steering position detector for self-traveling vehicle - Google Patents

Abstract

PURPOSE:To prevent erroneous detection performed by predicting the phase of reflected light detected this time based on the position of the reflected light detected last time, and employing the reflected light nearest to a predicted position. CONSTITUTION:Light projected from a projector 2 rotating by 360 deg. with a motor 5 is reflected on reflecting mirrors provided at three places, and is received with a receiver 3. An azimuth angle storage part 12 stores an azimuth receiving the reflected light. An azimuth angle prediction arithmetic part 27 calculates an azimuth angle detected this time based on that detected last time. An azimuth angle identification part 24 selects the azimuth angle nearest to a predicted azimuth angle among the azimuth angles stored in the azimuth angle storage part 12, and employs it as a detection azimuth angle. A position and progressive direction arithmetic part 13 calculates the position and the progressive direction of a self-traveling vehicle from those detection azimuth angles, and sets them as data for automatic steering.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a steering position detection device for a self-propelled vehicle, and particularly for self-propelled vehicles such as automobiles, unmanned transport devices in factories, agricultural and civil engineering machinery, etc. The present invention relates to a steering position detection device.

(Prior Art) Conventionally, as a device for detecting the current position of a moving object such as the above-mentioned self-propelled vehicle, a means for scanning an optical beam generated by the moving object in a circumferential direction centering on the moving object, and A device has been proposed that is fixed at at least three locations away from the body and is equipped with a light reflecting means that reflects light in the direction of incidence, and a light receiving means that receives the reflected light from the light reflecting means. Showa 59
-67476).

The device detects the aperture angle between the three light reflecting means as seen from the moving object based on the light receiving output of the light receiving means, and compares the detected aperture angle with each preset light reflecting means. The mobile object position is calculated based on the position information of the mobile object.

In the above system, the light beam may not be able to be irradiated to the light reflecting means due to the tilt or vibration of the self-propelled vehicle, or the light receiving means may receive reflected light from an object other than the light reflecting means. there were. If the reflected light from the scheduled light reflecting means is not reliably received, the position of the self-propelled vehicle will be calculated incorrectly, and as a result, the self-propelled vehicle will not be able to travel along the scheduled course.

On the other hand, for example, in Japanese Patent Application Laid-Open No. 59-104503, the position detection of a moving body is devised to ensure that the light beam is irradiated onto the light reflecting means by changing the scan speed and scan angle of the light beam. A method is proposed.

Furthermore, in Japanese Patent Application Laid-open No. 59-211816, by making the irradiation light generated by a moving body intermittent and periodic light, it is possible to distinguish the irradiation light from light from other light sources. A position detection device for a moving object has been proposed.

(Problem to be Solved by the Invention) In the former method of changing the scanning speed and angle of the light beam, it is necessary to frequently change the drive current of the optical scanner, which generates intermittent and periodic irradiation light. The latter device requires a complicated light source section to generate the irradiation light, and both systems have a problem in that the system configuration becomes complicated.

Furthermore, in addition to the obstacles caused by the tilting and vibration of the self-propelled vehicle,
There is also the problem that the reflected light cannot be reliably received due to dirt on the reflective surface of the light reflecting means or the appearance of a sudden obstruction such as a person or other object crossing in front of the first reflecting means. The above-mentioned conventional technology could not solve the problem.

An object of the present invention is to solve the problems of the prior art as described above, and to provide a method to prevent a self-propelled vehicle from traveling in the wrong direction even when the reflective means serving as a reference point for position detection is temporarily lost. An object of the present invention is to provide a steering position detection device for a self-propelled vehicle that can be used.

(Means and operations for solving the problems) In order to solve the above-mentioned problems and achieve the objects, the present invention scans a light beam in the circumferential direction around the self-propelled vehicle,
In a steering position detection device for a self-propelled vehicle configured to detect the position of the self-propelled vehicle by receiving reflected light of the light beam from a light reflecting means arranged at a reference point, means for detecting the azimuth of each light reflecting means as seen from the vehicle based on the light reception signal of the reflected light; and the azimuth of the light reflecting means to be detected in the next scan based on the detected azimuth. means for making a discrimination judgment of the light reflecting means for each azimuth in which the scanning of the forward beam has progressed by a predetermined angle from the predicted azimuth angle; and a means for detecting the incident light from the angle closest to the predicted azimuth, and determining that the received light signal of the detected incident light is from the intended reflecting means, and detecting the received light. The first feature is that the azimuth angle of the reflecting means calculated based on the signal is used to detect the position of the self-propelled vehicle.

Further, the present invention provides an identification angle range based on the predicted azimuth angle, and when the incident light is from an angle closest to the predicted azimuth angle or is from within the identification angle range, the identification angle range is determined. The second feature is that the received light signal of the incident light is determined to be from the intended reflecting means, and the azimuth of the reflecting means calculated based on the received light signal is used for detecting the position of the self-propelled vehicle. It has characteristics.

Furthermore, in the configuration having the first or second feature, if the incident light that can be determined to be reflected light from the intended reflecting means is not detected, the predicted azimuth angle is The third feature is that it is configured to be used for detecting the position of a self-propelled vehicle.

In the present invention having the above configuration, not only incident light from a noise source located in a direction far away from the predicted azimuth angle, but also incident light from a noise source located in a direction close to the predicted azimuth angle is reflected from the planned light reflecting means. It can be distinguished from reflected light.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 9 is a perspective view showing a self-propelled vehicle equipped with the control device of the present invention and the arrangement of light reflectors disposed in the travel area of the self-propelled vehicle. In the figure, a self-propelled vehicle 1 is, for example, a self-propelled vehicle for agricultural work such as a lawn mower. A rotary table 4 driven by a motor 5 is provided on the top of the self-propelled vehicle 1.

The rotary table 4 includes a light emitter 2 that generates a forward beam 2E.
A light receiver 3 is mounted to receive the reflected light 2R of the light beam.

The light emitter 2 includes a light emitting diode for generating a light beam 2E, and the light receiver 3 includes a photodiode for receiving reflected light 2R and converting it into an electrical signal (both not shown). Further, the rotary encoder 7 is provided so as to be interlocked with the drive shaft of the rotary table 4, and by counting the pulses output from the rotary encoder 7, the rotation angle of the rotary table 4 can be detected.

Reflectors 6a to 6C are arranged around the working area of the self-propelled vehicle 1. The reflectors 6a to 6C are provided with reflective surfaces that reflect incident light in the direction of incidence, and a known light reflecting means such as a so-called corner cube prism can be used.

With the above configuration, the light receiver 3 detects the reflected light from the reflectors 6a to 6C, and the reflectors 6a to 6C detect the reflected light from the reflectors 6a to 6C based on the detection signal.
Steering control is performed by detecting the self-position of the self-propelled vehicle 1 with respect to C.

By the way, if there is no reflective object or light-emitting object other than the reflector in or near the travel area of the self-propelled vehicle 1, is there no problem since only the light from the intended reflector is detected? The light receiver 3 may detect light from another object, or may not detect light reflected from the intended reflector.

Therefore, in this embodiment, whether or not the detected light is from a scheduled reflector is determined by the following process.

FIG. 2 is an explanatory diagram of the reference point identification process. In the figure, the reflector 6 is located at the reference point A-C around the work area 22.
a to 6c are arranged respectively.

An arrow 29 indicates the scanning direction of the light beam emitted from the self-propelled vehicle 1.

In the illustrated arrangement, the self-propelled vehicle 1 calculates the azimuth of each reference point as seen from the self-propelled vehicle 1 based on the signal received by the light receiver 3, and further calculates the azimuth of each reference point detected up to the present moment. Based on the angle, the azimuth angle of the reference point to be detected in the next scan is predicted.

The predicted azimuth angle (predicted azimuth angle) is the angle θpa ~ θpe
Indicated by The reference point identification direction p is set in the direction in which the scanning advances by the angle θh in the light beam scanning direction from each predicted azimuth θpa to θpc.
a-pc is set. This reference point identification direction p
Each time the light beam advances to a-pc, among the lights detected from the previous reference point identification direction to the current direction, the incident light from the direction closest to the predicted azimuth angle is set at the scheduled reference point. It is determined that the light is from a reflected reflector.

For example, in the reference point identification direction pa, if light from the noise sources Nl and N2 and the reflector 6a installed at the reference point A are detected from the previous reference point Takabetsu direction pC to the present, the Among them, light from the direction closest to the pre-MJ azimuth θpa, that is, light from the reference point A can be identified.

Furthermore, the following process can be added to improve the accuracy of identifying reference points. In other words, a predetermined range (an angle equal to or smaller than the angle θh) is set before and after the predicted azimuth, and if the light deviates from the range even if it is from the direction closest to the predicted azimuth, It is determined that the scheduled reference point has been lost, and the position of the self-propelled vehicle 1 in the processing cycle is detected using the predicted azimuth.

Next, the functional configuration of the control device of this embodiment will be explained according to the block diagram shown in FIG. In the figure, light emitter 2
The light beam 2E emitted from the rotary table 4 is scanned in the rotating direction of the rotary table 4, and is reflected by the reflector 6 (6a to 6c). The reflected light 2R from the reflectors 6a to 6c is received by the light receiver 3.

The counter 9 counts pulses output from the rotary encoder 7 as the rotary table 4 rotates. The count value of the pulse is transferred to the azimuth detecting section 11 every time the light receiver 3 detects light. The azimuth detection section 11 calculates the azimuths of the reflectors 6a to 6c based on the number of supplied pulses.

The azimuth detected by the azimuth detection unit 11 is stored in the azimuth storage unit 1.
The data stored in the azimuth storage unit 12 is transferred to the azimuth identification unit 24 in response to the identification timing signal supplied from the identification timing generation unit 23.

The identification timing signal is transmitted to the reference point identification azimuth pa-pc at the time when scanning has progressed to an azimuth that has passed through the azimuth indicated by the predicted azimuth calculated by the azimuth angle prediction calculation unit 27 by a predetermined angle θh. It is output when the beam scan progresses. For this purpose, the identification timing generator 23
Then, when a scheduled number of output pulses from the rotary encoder 7 corresponding to the predicted azimuth calculated by the azimuth angle prediction calculating section 27 are taken in, an identification timing signal is output.

The azimuth angle identification 824 identifies the light detected in the direction closest to the predicted azimuth angle calculated by the azimuth angle prediction calculation unit 27 from among the supplied azimuth angles, and the reflected light from a reflector placed at a predetermined reference point. It is determined that it is light.

The azimuth angle data of the reflector determined by this judgment is used when the azimuth angle prediction calculation unit 27 predicts the azimuth angle of the reflector to be detected in the next scan. That is, the predicted azimuth is determined by a function of the azimuth determined by the azimuth angle identification unit 24 that is expected to be obtained experimentally. The predicted azimuth angle is not limited to the method of calculating it based on a scheduled function.
The current azimuth may be determined by adding the difference between the current and previous azimuths obtained by the azimuth identification unit 24 to the current azimuth.

The azimuth detected by the azimuth angle identification section 24 is determined by the opening angle calculation section 1.
0, and the opening angle between the reflectors 6a to 6c as seen from the self-propelled vehicle 1 is calculated.

The position/progressing direction calculating section 13 calculates the current position coordinates of the self-propelled vehicle 1 based on the opening angle, and also calculates the traveling direction of the self-propelled vehicle 1 based on the azimuth angle. This calculation result is manually input to the comparing section 25.

The comparing section 25 compares the data representing the traveling course set in the traveling course setting section 16 with the coordinates and traveling direction of the self-propelled vehicle 1 obtained by the position/direction calculation section 13.

The comparison result is input to the steering section 14, and the steering motor 28 connected to the front wheels 17 of the self-propelled vehicle is driven based on the comparison result. The steering angle of the front wheels 17 by the steering motor 28 is detected by a steering angle sensor 15 provided on the front wheel of the self-propelled vehicle 1 and fed back to the steering section 14 . Drive control section 1
8 starts and stops the engine 19, and the engine 19
The operation of the clutch 2o that transmits the power to the rear wheels 21 is controlled.

In order to improve the identification accuracy of reference points, the following functions are added. That is, the range determining unit 26 determines whether the azimuth determined by the azimuth identifying unit 24 is within a predetermined range. According to this determination result, if the azimuth is within the planned range, the opening angle is calculated using the azimuth, and if it is outside the planned range, the prediction calculated by the azimuth prediction calculation unit 27 is used. Calculate the opening angle using the azimuth.

The self-propelled vehicle 1 determines whether the opening angle is calculated using the azimuth determined according to the determination result of the range determining unit 26 or the opening angle using the azimuth determined by the azimuth identifying unit 24. It may be selected arbitrarily according to the degree of accuracy required depending on the work style and type.

Of the components shown in FIG. 1, the portions surrounded by chain lines can be constructed by a microcomputer.

The basic principle for detecting the position and traveling direction of the self-propelled vehicle 1 in this embodiment with the above configuration will be explained. 7 and 8 show the positions of the self-propelled vehicle 1 and the reflector 6 in a coordinate system for indicating the working range of the self-propelled vehicle 1. FIG.

In FIGS. 7 and 8, reference points A, B, and C where reflectors 6a to 6c are arranged, and the position of self-propelled vehicle 1, connect reference points B and C with reference point B as the origin. It is expressed in an xy coordinate system with a straight line as the X axis.

As can be seen from the figure, the position T of the self-propelled vehicle 1 is located at the triangle A
It exists on the circumcircle of TB and at the same time on the circumcircle of triangle BTC. Therefore, the position of the self-propelled vehicle 1 is determined by calculating the two intersections of the circumscribed circles Q and P of the triangle ATB and the triangle BTC, respectively.

As shown in the figure, the position of the self-propelled vehicle 1 can be determined by setting the reference point B, which is the intersection of one of the circumscribed circles Q and P, as the origin, and calculating the other intersection T of the circumscribed circles Q and P according to the following procedure. .

The calculation formula for determining the position of the self-propelled vehicle 1 according to the basic principle is disclosed in Japanese Patent Application No. 116689/1989 and Japanese Patent Application No. 14/1983.
Since the details are shown in No. 9619, the details will be omitted.

Further, the traveling direction of the self-propelled vehicle 1 is calculated using the following formula. In FIG. 7, the angle between the traveling direction of the self-propelled vehicle 1 and the
, C, when θa, θb, θC are the azimuth angles of
......(1).

The position and traveling direction of the self-propelled vehicle 1 are calculated by the position and traveling direction calculating section 13 using the above-mentioned calculation formula and the above-mentioned calculation formula (1).

Next, steering control for controlling the traveling direction of the self-propelled vehicle 1 based on the position information of the self-propelled vehicle 1 calculated by the above procedure will be described. FIG. 6 is a diagram showing the positional relationship between the traveling course of the self-propelled vehicle 1 and a reference point, and FIG. 3 is a flowchart of steering control.

FIG. 6 shows the position of the self-propelled vehicle 1 and the work area 22 by the self-propelled vehicle 1 in a coordinate system with reference point B as the origin and a straight line passing through reference points B and C as the X axis. There is.

Point R (Xret, Yret) indicates the return position of the self-propelled vehicle 1, and the coordinates (Xs t, Ys t), (Xst, Ye
), (Xe Yst), and (Xe Ye) is the work area 22.

Here, the position T of the self-propelled vehicle 1 is indicated by (Xp, Yp).

In addition, in FIG. 6, in order to simplify the explanation, an example is shown in which the four sides of the work area 22 are parallel to the X axis or the y axis, but there are reference points A, B, . If C is placed, the shape of the work area 22 and the work area 22
The orientation of the four sides is arbitrary.

The control procedure will be explained according to the flowchart in FIG.

First, in step S1, the self-propelled vehicle 1 is moved from point R to the work start position by radio control.

In step S2, Xs is set as the X coordinate Xn of the driving course.
Set t and determine the driving course.

In step S3, the self-propelled vehicle 1 starts running.

In step S4, it is determined whether the light receiver 3 has received light from the reference point or another light source. A disconnection is made. When light is emitted, the process proceeds to step S5, where a light reception process to be described later is performed, and when no light is detected, the process proceeds to step S6.

In step S6, it is determined whether or not it is time to perform a reference point identification process to determine which of the received incident lights is from the scheduled reference point. This determination is made based on whether or not the scanning has progressed by a predetermined angle from the predicted azimuth calculated by the azimuth angle prediction/incorrection calculation section 27.

Steps 84 to S until the judgment in step S6 is affirmative
Step 6 is repeated, and if the determination is affirmative, the process proceeds to step S7, where a reference point identification process shown in a subroutine to be described later is executed. Once the azimuth of the scheduled reference point is determined by the reference point identification process, the process proceeds to step S8.

In step S8, the position T (Xp, Yp) of the self-propelled vehicle 1
And the direction of travel θf is calculated.

In step S9, the amount of deviation from the driving course (ΔX−X
p-Xn, Δθf) is calculated, and in step SIO,
Steering angle control is performed in the steering section 14 according to the calculated deviation amount.

In step Sll, it is determined whether the self-propelled vehicle 1 is traveling in a direction away from the origin (going direction) or in a direction approaching the origin (returning direction) in the y-axis direction.

If it is in the forward direction, it is determined in step S12 whether one stroke has ended (Yp>Ye); if in the backward direction, it is determined in step S13 that one stroke has ended (Yp>Ye).
It is determined whether or not <Yst)L. If it is determined in step S12 or S13 that one stroke has not been completed, steps 84 to S11 are performed.

If it is determined in step S12 or S13 that one row of culms has been completed, it is then determined in step S14 whether or not all processes have been completed (X n > X e - L).

If the entire stroke has not been completed, the process moves from step S14 to step S15, and U-turn control of the self-propelled vehicle 1 is performed. The U-turn control is different from the straight-line steering control performed by the SIO processing from step 88 to feed back the position information of the self-propelled vehicle 1 calculated by the position/direction calculation unit 13 to the steering unit 14. It is done by method.

That is, during the turning stroke, the self-propelled vehicle 1 travels with the steering angle fixed at a preset angle.

Then, when at least one of the azimuth angles of each of the reference points A, B, and C with respect to the self-propelled vehicle 1 matches within the predetermined angle range, the turning is stopped, and the straight forward movement is performed by the processing of steps 88 to 510. I am trying to return to normal steering control.

In step 816, Xn is set to Xn+L, and the driving course for the next stroke is set. Once the travel course is set, the process returns to step S4 and the above process is repeated.

When the entire stroke is completed, the return position R (Xret.Yre
Returning to step t) (step S17), the traveling is stopped (
Step S18).

Next, the light reception process and reference point identification process in steps S5 and S7 will be explained.

A flowchart of the light reception process is shown in FIG. In the same figure, in step S50, "1" is set in the light reception flag in order to memorize that light has been detected.

In step S51, the azimuth of the detected light source is stored in the azimuth storage section 12.

A flowchart of the reference point identification process is shown in FIG. This flowchart shows an example of a procedure in which the range determination section 26 further narrows down the detection/results.

In the figure, in step S70, a value n of a pole counter (hereinafter simply referred to as a pole counter) for distinguishing a reference point to be identified is incremented. The ball counter is associated with each reference point. That is, the pole counter "1" is at the reference point A, and the pole counter "2' is at the reference point A.
corresponds to reference point B, and pole counter "3" corresponds to reference point C, respectively.

If the initial value of the pole counter is “0”, Stenob S
As a result of the process 70, the poll counter becomes "1", and the reference point corresponding to this becomes "A". In this embodiment, the initial value is set to "0".

In step S71, the light reception flag is determined. If the light reception flag is "1", the process proceeds to step S72, and if the light reception flag is "0", the process jumps to step S79.

In step S72, the predicted azimuth θpn (since the pole counter is set to “1”, the predicted azimuth θp
Assume that the one closest to a) is the azimuth angle of the scheduled reference point, and store that value as the angle θS.

In step S73, the presence or absence of noise is determined by determining whether the number of received lights is "2" or more, that is, whether a plurality of azimuths are stored in the azimuth storage section 12.

If the determination in step S73 is affirmative, it is determined that noise has been detected, and the process moves to step S74, in which the fact that noise has been detected is stored as noise processing.

This stored data will later provide clues about the state of the work environment, making it easier to take measures such as eliminating noise sources.

If the determination in step S73 is negative, the process proceeds to step S75, where the temporarily determined azimuth θS and the predicted azimuth θp are
It is determined whether the difference with n (predicted azimuth θpa) is smaller than the angle θh. If the difference is larger than the angle θh, it is determined that the temporarily determined azimuth θS is not the azimuth of the planned reference point but the azimuth of the noise source, and the process proceeds to step S7g, where the same process as in step S74 is performed. Perform noise processing.

After the noise processing, the process proceeds to step S79, where the predicted azimuth θpn (predicted azimuth θpa
) is set as the azimuth angle θn (θa) of the scheduled reference point.

On the other hand, if the difference is smaller than the angle θh, the assumed azimuth θS is determined to indicate the azimuth of the scheduled reference point, and the process proceeds to step S76.

In step 576, the azimuth θ determined in the previous process is
Based on n and the azimuth θS determined in the current process, the predicted azimuth at which the same reference point should be detected in the next process is calculated using the formula {θs+(θSθnN).

In step S77, the azimuth angle θn is updated with the angle θS.

In step S80, the next reference point identification direction pn+1(
That is, the predicted azimuth θpH+ calculated when the reference point B was detected during the previous scan is used as the reference point identification azimuth pb).
Set the angle obtained by adding the planned angle θh to l.

In step S81, the light reception flag is reset.

In step S82, the data stored in the azimuth storage section 12 is erased.

In step S83, it is determined whether the poll counter is "3" or not. The value "3" is the number of installed reference points, and is set according to the number of installed reference points.

If the number of installed reference points matches the pole counter, the pole counter is set to "0" in step S84 and the process returns to the main routine (processing in FIG. 3).

When the ball counter is "1", in the next process, the pole counter is incremented to "2" in step S70, and the reference point B identification process is performed.

Thereafter, identification processing for the reference point C is also performed in the same manner.

As described above, in this embodiment, when a plurality of lights are detected by the light receiver 3, among the plurality of lights, the light from the direction closest to the predicted azimuth angle, and Light from a direction that does not deviate from the predicted azimuth by more than a predetermined angle is determined to be reflected light from a predetermined reference point.

Further, when the scheduled reference point is lost, the predicted azimuth angle is used to detect the position of the self-propelled vehicle 1.

In this embodiment, all of the light detected between each reference point identification azimuth is stored in the azimuth storage unit, and reference points are identified using these. A predetermined target angle range may be provided, and azimuth data of only the light detected within this range may be stored, and the reference point may be identified using the stored data.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects can be obtained.

(1) Since the light reflected from the reflector placed at the reference point and the light from other light sources can be distinguished, the position of the self-propelled vehicle can be detected using light reflecting objects and light sources in the work area and its surroundings. Negative effects on control can be eliminated.

(2) Even if the reference point is temporarily lost, the position of the self-propelled vehicle can be detected using the predicted azimuth, so there is no need to interrupt the travel of the self-propelled vehicle. Therefore, work can be carried out even in areas where the self-propelled vehicle rolls a little or areas with large ups and downs, and the scope of work by the self-propelled vehicle can be expanded.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of reference point identification processing, FIG. 3 is a flowchart of steering control, FIG. 4 is a flowchart of reference point identification processing, and FIG. The figure is a flowchart of light reception processing, Figure 6 is a diagram showing the traveling course of a self-propelled vehicle and the arrangement of reflectors, Figure 7 is a diagram explaining the principle of position detection of a self-propelled vehicle, and Figure 8 is a diagram showing the position detection of a self-propelled vehicle. FIG. 9, which is a diagram explaining the principle of detecting the traveling direction, is a perspective view showing the arrangement of the self-propelled vehicle and the reflector. 1... Self-propelled vehicle, 2... Emitter, 3... Light receiver, 6
, 6a to 6C... reflector, 11... azimuth angle detection section,
DESCRIPTION OF SYMBOLS 12... Azimuth storage part, 13... Position/progressing direction calculation part, 14... Steering part, 23... Identification timing generation part, 24... Azimuth angle identification part, 25... Comparison Part, 2
6... Range determination unit, 27... Azimuth angle prediction calculation unit

Claims (5)

[Claims] (1) A light beam generated by a self-propelled vehicle is scanned in a circumferential direction centering on the self-propelled vehicle, and reflected light of the light beam from light reflecting means arranged at at least three reference points is detected. A steering position detection device for a self-propelled vehicle that detects the position of the self-propelled vehicle by receiving light, comprising: means for detecting the azimuth of each light reflecting means as seen from the self-propelled vehicle based on reflected light; and the azimuth angle. means for predicting the azimuth of each light reflection means to be detected in the next scan based on the azimuth detected by the detection means; and a light beam for a predetermined angle from the predicted azimuth of each light reflection means. A reference point identification direction is set for each direction in which the scanning has progressed, and among the incident light detected from the previous reference point identification direction to the current direction in the reference point identification direction, from the angle closest to the predicted azimuth. A steering position detection device for a self-propelled vehicle, comprising means for determining that incident light is reflected light from a reflecting means disposed at a predetermined reference point. (2) If the incident light from the angle closest to the predicted azimuth is light from an angular range established with the predicted azimuth as a reference, the incident light is placed at a predetermined reference point. 2. The steering position detection device for a self-propelled vehicle according to claim 1, further comprising means for determining that the light is reflected from a reflected light reflecting means. (3) If no incident light is detected that can be determined to be reflected light from the reflecting means placed at the scheduled reference point,
3. The steering position detection device for a self-propelled vehicle according to claim 1, wherein the device is configured to detect the position of the self-propelled vehicle based on the predicted azimuth. (4) comprising means for storing only the azimuth of light detected within an angular range set with the predicted azimuth as a reference, and the azimuth stored in the storage means is used as the reference point identification azimuth The steering position detection device for a self-propelled vehicle according to any one of claims 1 to 3, characterized in that the device is treated as an object to be identified. (5) The means for predicting the azimuth of each light reflecting means to be detected in the next scan is a means for predicting the azimuth based on the difference between the azimuths of the light reflecting means detected in the previous and latest scans. The steering position detection device for a self-propelled vehicle according to any one of claims 1 to 4.