JPH0833766B2 - Self-propelled vehicle steering position detection device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering position detecting device for a self-propelled vehicle, and in particular,
The present invention relates to a steering position detection device for an automobile, an unmanned mobile transportation device in a factory, a self-propelled vehicle such as an agricultural machine or a civil engineering machine.

(Prior Art) Conventionally, as a device for detecting the current position of a moving body such as the above-mentioned self-propelled vehicle, means for scanning a light beam generated by the moving body in a circumferential direction around the moving body, An apparatus has been proposed which is fixed to at least three locations apart from the body and includes a light reflecting means for reflecting light in the incident direction and a light receiving means for receiving the reflected light from the light reflecting means (Japanese Patent Laid-Open No. 2004-242242). Akira
59-67476 publication).

The device detects an opening angle between the three light reflecting means viewed from a moving body based on a light receiving output of the light receiving means, and the detected opening angle and each light reflecting means set in advance. It is configured to calculate the position of the moving body based on the position information of.

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

On the other hand, for example, in Japanese Patent Laid-Open No. 59-104503, a method for detecting the position of a moving body is devised so that the light beam can be reliably irradiated onto the light reflecting means by changing the scanning speed and the scanning angle of the light beam. Is proposed.

Further, in Japanese Patent Laid-Open No. 59-211816, it is possible to distinguish the irradiation light from the light from other light sources by making the irradiation light generated by the moving body intermittent and periodic. A position detecting device for a moving body devised in the above has been proposed.

(Problems 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 change the drive current of the optical scanner frequently, so that intermittent and periodic irradiation light is generated. In the latter device described above, there is a problem in that the system configuration is complicated in both cases, such as requiring a complicated light source unit for generating the irradiation light.

Furthermore, in addition to obstacles caused by the inclination and vibration of the self-propelled vehicle, dirt on the reflecting surface of the light reflecting means, or the emergence of a sudden shield such as a person or other object passing in front of the light reflecting means. However, there is also a problem that the reflected light cannot be reliably received, and these problems cannot be solved by the above-mentioned prior art.

An object of the present invention is to solve the above-mentioned problems of the prior art and to prevent the self-propelled vehicle from traveling in the wrong direction even when the reflecting means serving as a reference point for position detection is lost temporarily. An object is to provide a steering position detecting device for a self-propelled vehicle.

(Means and Actions for Solving the Problem) In order to solve the above-mentioned problems and achieve the object, the present invention scans a light beam in a circumferential direction around a self-propelled vehicle, and at least three points are provided. In a steering position detecting device for a self-propelled vehicle configured to receive the reflected light of the light beam from the light reflecting means arranged at the reference point, and to detect the position of the self-propelled vehicle, Means for detecting the azimuth angle of each of the reflecting means as seen based on the received light signal of the reflected light, and predicting the azimuth angle of the light reflecting means to be detected in the next scan based on the detected azimuth angle. Means, means for making an identification judgment of the light reflecting means for each azimuth in which the scanning of the light beam has proceeded from the predicted azimuth angle by a predetermined angle, and prediction of incident light detected between the respective identification judgment azimuths. Incident light from an angle closest to the azimuth angle And a azimuth angle of the reflecting means calculated based on the received light signal, which is determined based on the received light signal. The first feature is that it is configured to be used for position detection of.

Further, the present invention provides an identification angle range based on the predicted azimuth angle, and when incident light from an angle closest to the predicted azimuth angle is within the identification angle range, The second point is that the received light signal of the incident light is determined to come from the expected reflecting means, and the azimuth angle of the reflecting means calculated based on the received light signal is used for position detection of the vehicle. There are features.

Further, according to the present invention, in the configuration having the first or second feature, when the incident light that can be determined to be the reflected light from the scheduled reflecting means is not detected, the predicted azimuth angle is set to the predicted azimuth angle. A third feature is that the vehicle is configured to be used for detecting the position of a self-propelled vehicle.

In the present invention having the above configuration, not only the noise source in the direction largely deviated from the predicted azimuth angle, but also the incident light from the noise source in the direction close to the predicted azimuth angle from the scheduled light reflection means. It can be distinguished from the reflected light.

Embodiment 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 a light reflector disposed in a traveling area of the self-propelled vehicle. In the figure, the self-propelled vehicle 1 is a self-propelled vehicle for agricultural work such as a lawn mower. A rotary table 4 driven by a motor 5 is provided above the self-propelled vehicle 1. The rotary table 4 has a light emitting device 2 for generating a light beam 2E and a light receiving device 3 for receiving the reflected light 2R of the light beam.
Is installed.

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

Reflectors 6a to 6c are arranged around the work area of the vehicle 1. Each of the reflectors 6a to 6c has a reflecting surface that reflects incident light in the incident direction, and a known light reflecting means such as a so-called corner cube prism can be used.

With the above configuration, the reflected light from the reflectors 6a to 6c is detected by the light receiver 3, and the steering position control is performed by detecting the self-position of the vehicle 1 with respect to the reflectors 6a to 6c based on the detection signal. Be seen.

By the way, if there is no reflecting object or light emitting object other than the reflector in or near the traveling area of the self-propelled vehicle 1, there is no problem because only the light from the planned reflector is detected. The light receiver 3 may detect light from another object, or may not be able to detect the reflected light from a planned reflector.

Therefore, in the present embodiment, whether or not the detected light is light from the intended reflector is identified by the following processing.

FIG. 2 is an explanatory diagram of the reference point identification processing. In the figure, reference points A to C around a work area 22 have the reflector 6a.
~ 6c are arranged respectively. The arrow 29 indicates the scanning direction of the light beam emitted from the vehicle 1.

In the arrangement shown in the figure, in the self-propelled vehicle 1, the light receiver 3
The azimuth angle of each reference point viewed from the self-propelled vehicle 1 is calculated based on the signal received by the vehicle 1, and the azimuth angle of the reference point to be detected in the next scan based on the azimuth angle detected up to the present time. Corners are predicted. Predicted azimuth (predicted azimuth)
Denotes the angles θpa to θpc. The reference point identification azimuths pa to pc are set in the azimuths in which the scanning advances from the predicted azimuth angles θpa to θpc by the angle θh in the light beam scanning direction. This reference point identification azimuth
Every time the scanning of the light beam progresses from pa to pc, the incident light from the direction closest to the predicted azimuth angle among the lights detected from the immediately preceding reference point identification azimuth to the current azimuth is set at the planned reference point. It is determined that the light is from the reflected reflector.

For example, when light from the noise sources N1 and N2 and the reflector 6a installed at the reference point A is detected from the immediately preceding reference point identification azimuth pc to the present in the reference point identification azimuth pa, Therefore, light from a direction close to the predicted azimuth angle θpa, that is, light from the reference point A can be identified.

Further, the following processing can be added to improve the reference point identification accuracy. That is, a planned range (angle equal to or smaller than the angle θh) is provided before and after the predicted azimuth, and even if light from the direction closest to the predicted azimuth is out of the range, the planned range is set. It is determined that the reference point has been lost, and the position of the vehicle 1 in the processing cycle is detected using the predicted azimuth angle.

Next, the functional configuration of the control device of this embodiment will be described with reference to the block diagram shown in FIG. In the figure, the light beam 2E emitted from the light emitter 2 is the rotary table 4
Is scanned in the rotating direction of 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 the pulses output from the rotary encoder 7 as the rotary table 4 rotates. The count value of the pulse is transferred to the azimuth angle detection unit 11 every time the light receiver 3 detects light. In the azimuth angle detector 11, the azimuth angles of the reflectors 6a to 6c are calculated based on the number of supplied pulse pulses.

The azimuth detected by the azimuth detector 11 is the azimuth memory 12
The data which has been transferred and stored in the azimuth storage unit 12 so far 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 azimuth indicated by the predicted azimuth calculated by the azimuth prediction calculation unit 27 at a point in time when the scanning has advanced to the azimuth that has passed the predetermined angle θh, that is, the reference point identification azimuths pa to pc. It is output when the scanning of the beam progresses. For this reason, the identification timing generation unit 23 outputs the identification timing signal at the time when a predetermined number of output pulses of the rotary encoder 7 corresponding to the predicted azimuth angle calculated by the azimuth angle prediction calculation unit 27 are fetched.

The azimuth angle identifying unit 24 detects, from among the supplied azimuth angles, the light detected in the direction closest to the predicted azimuth angle calculated by the azimuth angle prediction calculation unit 27 from the reflector arranged at the predetermined reference point. Judge as reflected light. The azimuth data of the reflector determined by this determination is used when the azimuth prediction calculation unit 27 predicts the azimuth of the reflector to be detected in the next scan. That is, the predicted azimuth angle is obtained by an experimentally obtained function of the azimuth angle determined by the azimuth identification unit 24. The predicted azimuth is not limited to the method of obtaining the predicted azimuth based on a predetermined function, and the difference between the present and previous azimuths obtained by the azimuth identifying unit 24 may be added to the present azimuth.

The azimuth angle detected by the azimuth angle identification 24 is input to the opening angle calculation unit 10 and the opening angle between the reflectors 6a to 6c viewed from the vehicle 1 is calculated.

The position / traveling direction computing unit 13 computes the current position coordinates of the traveling vehicle 1 based on the opening angle and the traveling direction of the traveling vehicle 1 based on the azimuth angle. This calculation result is input to the comparison unit 25. The comparison unit 25 compares the data representing the traveling course set in the traveling course setting unit 16 with the coordinates and traveling direction of the self-propelled vehicle 1 obtained by the position / traveling direction calculation unit 13.

The comparison result is input to the steering unit 14, and the steering motor 28 connected to the front wheels 17 of the vehicle is driven based on the comparison result. The steering angle of the front wheels 17 by the steering motor 28 is detected by the steering angle sensor 15 provided on the front wheels of the self-propelled vehicle 1, and the steering section
Feedback on 14. The drive control unit 18 is the engine 19
It controls the start and stop of the engine and the operation of the clutch 20 that transmits the power of the engine 19 to the rear wheels 21.

The following functions are added to improve the reference point identification accuracy. That is, the range discriminating unit 26 discriminates whether or not the azimuth determined by the azimuth discriminating unit 24 is within the predetermined range. According to this determination result, if the azimuth angle is within the planned range, the azimuth angle is used to calculate the opening angle, and if the azimuth angle is outside the planned range, the prediction calculated by the azimuth angle prediction calculation unit 27 is calculated. Use the azimuth angle to calculate the opening angle.

Whether the open angle is calculated by using the azimuth angle determined according to the determination result of the range determining unit 26 or the azimuth angle determined by the azimuth angle identifying unit 24 is used by the vehicle 1.
It may be arbitrarily selected according to the degree of accuracy required depending on the work form or type.

It should be noted that, of the constituent elements shown in FIG. 1, a portion surrounded by a chain line can be constituted by a microcomputer.

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

In FIGS. 7 and 8, the reference points A, B, C on which the reflectors 6a to 6c are respectively arranged and the positions of the self-propelled vehicle 1 are:
With reference point B as the origin, a straight line connecting reference points B and C is x
Expressed in an xy coordinate system as an axis.

As can be seen from the figure, the position T of the self-propelled vehicle 1 is a triangle.
It is on the circumscribed circle of ATB and at the same time on the circumscribed circle of BTC. Therefore, the position of self-propelled vehicle 1 is triangular AT
It is obtained by calculating the two intersections of the circumscribed circles Q and P of B and the triangle BTC, respectively.

As shown, a reference point B, which is one of the intersections of the circumscribed circles Q and P, is set as the origin, and the other intersection T of the circumscribed circles Q and P is used as the origin.
The position of the self-propelled vehicle 1 can be determined by calculating the following procedure.

The calculation formula for determining the position of the self-propelled vehicle 1 according to the basic principle is described in detail in Japanese Patent Application Nos. 63-116689 and 63-149619, and therefore omitted.

The traveling direction of the self-propelled vehicle 1 is calculated using the following formula. In FIG. 7, an angle between the traveling direction of the self-propelled vehicle 1 and the x axis is θf, and reference points A, B, and
When the azimuth angles of C, are θa, θb, and θc, θf = 360 ° −tan ⁻¹ {y / (xc−x)} − θc (1).

The position and traveling direction of the self-propelled vehicle 1 are calculated by the position / traveling direction calculation unit 13 using the above-described calculation formula and the 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 a positional relationship between the traveling course of the self-propelled vehicle 1 and the reference point, and FIG. 3 is a flowchart of steering control.

In FIG. 6, the reference point B is set as the origin, and the reference points B and C are set.
The position of the self-propelled vehicle 1 and the work area 22 by the self-propelled vehicle 1 are shown in a coordinate system having a straight line passing through as the x-axis.

The point R (Xret, Yret) indicates the return position of the self-propelled vehicle 1 and is connected by points indicated by coordinates (Xst, Yst), (Xst, Ye), (Xe, Yst), (Xe, Ye). The area is the work area 22. Here, the position T of the self-propelled vehicle 1 is indicated by (Xp, Yp).

Note that, in FIG. 6, an example in which the four sides of the work area 22 are parallel to the x-axis or the y-axis is shown for simplification of description, but the reference points A, B, C are arranged around the work area 22. If is arranged, the shape of the work area 22 and the directions of the four sides of the work area 22 are arbitrary.

The control procedure will be described with reference to the flowchart of FIG.

First, in step S1, the mobile vehicle 1 is moved from the point R to the work start position by radio control. In step S2, Xst is set as the x coordinate Xn of the traveling course to determine the traveling course.

 In step S3, the traveling of the self-propelled vehicle 1 is started.

In step S4, it is determined whether or not the light receiver 3 has received light from a reference point or another light source. When the light is detected, the process proceeds to step S5, and the light receiving process described later is performed. When the light is not detected, the process proceeds to step S6.

In step S6, it is determined whether or not it is time to perform the reference point identification process for determining which of the received incident light is the light from the predetermined reference point. The determination is made based on whether or not the scanning has advanced by a predetermined angle from the predicted azimuth calculated by the azimuth prediction calculation unit 27.

Steps S4 to S6 are repeated until the determination in step S6 is affirmative, and if the determination is affirmative, the process proceeds to step S7, and the reference point identification process shown in the subroutine described below is executed. When the azimuth angle of the planned reference point is determined by the reference point identification processing, the process proceeds to step S8.

In step S8, the position T (Xp, Yp) of the vehicle 1 and the traveling direction θf are calculated.

In step S9, the amount of deviation from the traveling course (ΔX = Xp
−Xn, Δθf) is calculated, and in step S10, the steering angle control is performed in the steering unit 14 according to the calculated shift amount.

In step S11, it is determined whether the vehicle 1 is traveling in the y-axis direction in a direction away from the origin (going direction) or in a direction approaching the origin (returning direction).

If it is for directions, it is determined in step S12 whether or not the one stroke has been completed (Yp> Ye). If it is in the return direction, in step S13 whether or not the one stroke has been completed (Yp <Yst). Is judged. If it is determined in step S12 or S13 that one stroke has not ended, step S4
~ The processing of S11 is performed.

If it is determined in step S12 or S13 that one stroke is completed, then it is determined in step S14 whether or not the entire stroke is completed (Xn> Xe-L).

If the entire process is not completed, the process proceeds from step S14 to step S15, and the U-turn control of the vehicle 1 is performed.
The U-turn control is different from the steering control for the straight travel distance performed by the processing of steps S8 to S10 for feeding back the position information of the vehicle 1 calculated by the position / travel direction calculation unit 13 to the steering unit 14. Done in a manner.

That is, in the turning stroke, the steering angle of the self-propelled vehicle 1 is fixed to a preset angle and allowed to travel. Then, when at least one of the azimuth angles 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,
The steering control for the straight travel is performed by the processing in steps S8 to S10.

In step S16, Xn is set to Xn + L, and the next course of travel is set. When the traveling course is set, the process returns to step S4 and the above process is repeated.

When the entire process is completed, the vehicle returns to the return position R (Xret, Yret) (step S17) and the traveling is stopped (step S).
18).

Next, the light receiving process and the reference point identifying process in steps S5 and S7 will be described.

A flowchart of the light receiving process is shown in FIG. In the figure, in step S50, "1" is set to a light receiving flag to store that light has been detected.

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

FIG. 4 shows a flowchart of the reference point identification processing. The flowchart shows an example of a procedure in which the range determination unit 26 further narrows down the detection result. In the figure, in step S70, a value of a pole counter for distinguishing a reference point to be identified (hereinafter, simply referred to as a pole counter) n
Is incremented. The pole counter is associated with each reference point. That is, the pole counter “1” corresponds to the reference point A, the pole counter “2” corresponds to the reference point B, and the pole counter “3” corresponds to the reference point C.

If the initial value of the pole counter is "0", step S7
By the processing of 0, the poll counter becomes "1", and the reference point corresponding to this becomes A. In this embodiment, the initial value is "0".

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

In step S72, among the azimuths of the light sources stored in the azimuth storage unit 12, the azimuth closest to the predicted azimuth θpn (the predicted azimuth θpa since the pole counter is “1”) Is assumed to be the azimuth of the planned reference point, and the value is stored as the angle θs.

In step S73, the presence or absence of noise is determined by determining whether the number of received light is “2” or more, that is, whether or not a plurality of azimuth angles are stored in the azimuth angle storage unit 12.

If the determination in step S73 is affirmative, it is determined that noise has been detected, the process proceeds to step S74, and the fact that noise has been detected is stored as noise processing. This stored data gives a clue to know the condition of the work environment later, and it becomes easy to take measures such as removal of noise sources.

If the determination in step S73 is negative, the process proceeds to step S75, and it is determined whether or not the difference between the temporarily determined azimuth angle θs and the predicted azimuth angle θpn (predicted azimuth angle 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 step S78
And the same noise processing as in step S74 is performed.

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

On the other hand, if the difference is smaller than the angle θh, the assumed azimuth θs is determined as indicating the azimuth of the predetermined reference point, and the process proceeds to step S76.

In step S76, the azimuth θ determined in the previous process
Based on n and the azimuth angle θs determined in this processing, the predicted azimuth angle at which the same reference point should be detected in the next processing is calculated using the calculation formula {θs + (θs−θn)}.

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

In step S80, as the next reference point identification azimuth pn + 1 (that is, the reference point identification azimuth pb), an angle obtained by adding the expected angle θh to the predicted azimuth θpn + 1 calculated when the reference point B was detected in the previous scan is set. To do.

 In step S81, the light receiving flag is reset.

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

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

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

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

 Hereinafter, the identification process of the reference point C is performed in the same manner.

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

In addition, when the user loses sight of the planned reference point, the predicted azimuth is determined by using the position detection of the vehicle 1.

In the present embodiment, all of the light detected between the reference point identification azimuths is stored in the azimuth angle storage unit, and the reference points are identified for these objects. It is also possible to provide a predetermined target angle range, store the azimuth data of only the light detected therein, and identify the reference point with the stored data as the target.

(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 reflected light can be distinguished from the light from other light sources from the reflector arranged at the reference point, the position detection control of the self-propelled vehicle by the light reflecting object or light emitting source in the work area and its surroundings It is possible to eliminate the adverse effect on.

(2) Even if the reference point is temporarily lost, the position of the self-propelled vehicle can be detected by using the predicted azimuth, so that the traveling of the self-propelled vehicle is not interrupted. Therefore, the work can be performed even in an area where the self-propelled vehicle rolls to some extent or in an area where the self-propelled vehicle has a large ups and downs, and the applicable range of the work by the self-propelled vehicle can be expanded.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory view 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. Fig. 6 is a flowchart of the light receiving process, Fig. 6 is a diagram showing the traveling course of the self-propelled vehicle and the arrangement of reflectors, Fig. 7 is an explanatory view of the principle of the position detection of the self-propelled vehicle, and Fig. 8 is the FIG. 9 is a perspective view showing the principle of detecting the traveling direction, and FIG. 9 is a perspective view showing the arrangement state of the vehicle and the reflector. 1 ... self-propelled vehicle, 2 ... light-emitting device, 3 ... light-receiving device, 6, 6a-6c
...... Reflector, 11 …… Azimuth detection unit, 12 …… Azimuth storage unit, 13 …… Position / travel direction calculation unit, 14 …… Steering unit, 23 ・ ・ ・
… Identification timing generation part, 24 …… Azimuth angle identification part, 25 ……
Comparison unit, 26 ... 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 around the self-propelled vehicle, and the light beam is reflected from light reflecting means arranged at at least three reference points. In a steering position detecting device for a self-propelled vehicle that receives light and detects the position of the self-propelled vehicle, means for detecting the azimuth angle of each light reflecting means viewed from the self-propelled vehicle based on reflected light, Based on the azimuth angle detected by the azimuth angle detection means, a means for predicting the azimuth angle of each light reflecting means to be detected in the next scan, and a predetermined angle from the predicted azimuth angle of each light reflecting means A reference point identification azimuth is set for each azimuth in which the scanning of the light beam has progressed, and in the reference point identification azimuth, the incident light detected from the immediately preceding reference point identification azimuth to the current azimuth is the closest to the predicted azimuth angle. Incident light from an angle is reflected from a reflection means arranged at a predetermined reference point. Self-propelled vehicle steering position detecting device being characterized in that and means for determining that the Shako. 2. When the incident light from an angle closest to the predicted azimuth is light from an angle range provided with the predicted azimuth as a reference, the incident light is set to a predetermined reference point. 2. The steering position detecting device for a self-propelled vehicle according to claim 1, further comprising means for determining that the light is reflected light from the light reflecting means arranged at. 3. When the incident light that can be judged to be the reflected light from the reflecting means arranged at the predetermined reference point is not detected, the position of the vehicle is detected based on the predicted azimuth angle. The steering position detection device for a self-propelled vehicle according to claim 1 or 2, wherein the steering position detection device is configured to perform the operation. 4. A means for storing only the azimuth angle of light detected within an angle range provided with the predicted azimuth angle as a reference, and the azimuth angle stored in the storage means is used as the reference point identification. The steering position detecting device for a self-propelled vehicle according to any one of claims 1 to 3, wherein the steering position detecting device is treated as an identification target in the azimuth. 5. The means for predicting the azimuth angle of each light reflecting means to be detected in the next scan predicts the azimuth angle based on the difference between the azimuth angles of the light reflecting means detected in the previous and latest scans. It is a means to do, The Claims 1-4 characterized by the above-mentioned.
A steering position detecting device for a self-propelled vehicle according to any one of 1.