JP3245284B2 - Self-position detection method for autonomous mobile work vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention recognizes a plurality of signs installed in the vicinity of a specific work area, detects its own position, and performs self-positioning of an autonomous traveling work vehicle that performs work traveling in mowing, lawn mowing work and the like. It relates to a detection method.

[0002]

2. Description of the Related Art Conventionally, for an autonomous vehicle that runs unmanned and autonomously, a technique of burying an electric wire underground and detecting a magnetic field generated by the electric wire with a magnetic sensor is used as a self-position detection for the autonomous driving. It has been proposed, but if the autonomous traveling area is vast, such as an autonomous traveling vehicle that performs unattended work such as mowing and lawn mowing in various fields such as golf courses, river banks, parks, etc. It is difficult to bury the wires, and the installation cost is high.

For this reason, a technology has been developed in which a plurality of signs are installed in the vicinity of an area in which autonomous traveling is performed, and the signs are recognized to detect the position of the own vehicle.
Japanese Patent No. 5606 discloses that a plurality of retroreflective poles (light reflective signs) erected in a specific area are projected, the reflected light is received by an optical sensor, and an angle at which an adjacent reflective pole is faced is detected. There has been disclosed a technology for detecting a self-position by a three-point included angle method (triangulation method) from an angle obtained and known coordinates of a sign.

[0004]

However, in an autonomous traveling work vehicle, since the vehicle inclines or vibrates due to autonomous traveling in a work area having irregular terrain or undulation,
In some cases, the projected light beam may fall off the sign, or it may be difficult to receive the reflected light from the sign, and the self-position may not be detected due to the loss of the sign.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to reliably recognize a sign without being affected by vehicle inclination or vehicle vibration in an uneven terrain or undulating area, and to obtain an accurate sign. It is an object of the present invention to provide a method for detecting a self-position of an autonomous traveling work vehicle capable of detecting a self-position.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for detecting a self-position of an autonomous traveling work vehicle, which recognizes a plurality of signs set around a specific work area and detects a self-position by triangulation. The work vehicle is provided with a rotation mechanism for rotating the imaging means so that the entire circumference can be imaged, and the imaging means sets the rotation speed of the rotation mechanism and the imaging angle of view of the imaging means at each time interval set by the imaging means. A surrounding image including a sign is taken, and the sign is recognized by obtaining a feature amount of the sign from a plurality of taken images.

[0007]

According to the present invention, the image pickup means is rotated via a rotation mechanism provided on the autonomous traveling work vehicle, and the surrounding image including the sign is set at each time interval set based on the rotation speed and the image pickup angle of view of the image pickup means. Is imaged. Then, the characteristic amount of the sign is obtained from the plurality of captured images to recognize the sign, and the self-position is detected by triangulation.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a flowchart of a self-position detection routine, FIG. 2 is a flowchart of a main control routine, FIG. 3 is a schematic explanatory view showing the appearance of a lawn mowing vehicle, and FIG. FIG. 5 is a block diagram showing a circuit configuration of a vehicle position detecting unit, FIG. 6 is an explanatory diagram showing a traveling route and a work area, and FIG. 7 is an explanatory diagram of self-position detection by triangulation.

In FIG. 3, reference numeral 1 denotes an autonomous traveling work vehicle capable of running unmanned and autonomously. In this embodiment, the vehicle is a lawn mowing vehicle that performs grass and lawn mowing work at a golf course or the like. The lawn mower 1 is driven by an engine and can independently control the steering angles of the front and rear wheels.
A cutting blade mechanism 2 such as a mower for grass and lawn mowing work is provided at the lower part of the vehicle body, a dead reckoning sensor for measuring a current position based on a running history, and a sensor for detecting a running obstacle. It is equipped with sensors for obstacle detection, sensors for profiling running along the boundaries of mowing in the grass and lawn mowing work area, and a plurality of signs standing around the grass and lawn mowing work area. And an image pickup means for recognizing a sign from the picked-up image and detecting its own position by triangulation.

As the dead reckoning sensor, a terrestrial magnetism sensor 3 and a wheel encoder 4 are provided in the lawn mowing vehicle 1. As the obstacle detection sensor, a non-contact type sensor such as an ultrasonic sensor or an optical sensor is used. Sensors 5a, 5b
Are attached to the front and rear portions of the lawn mower 1 and have contact type sensors 6a,
6b are attached to the front and rear ends of the lawn mowing vehicle 1.

[0011] Further, as the scanning travel sensor, for example, a sled-shaped plate that moves up and down according to grass and lawn height, and a rotary encoder that detects the rotation angle of a member that supports the sled-shaped plate are assembled. In addition, a cut boundary detection sensor 7 for detecting a cut boundary between the already cut portion and the uncut portion is provided in a lower portion of the vehicle body of the lawn mowing vehicle 1.

As an image pickup means for picking up an image of a sign, for example, a CCD using a solid-state image pickup device (CCD) is used.
Camera is used. This CCD camera is provided on a rotating mechanism 10 erected in front of the lawn mowing vehicle 1 as an image pickup unit 8 integrated with an illumination light covering the field of view of the CCD camera. Is mounted in a state of facing 360 °, and is rotated 360 ° around the mounting axis to enable full-circle imaging.

The self-position detection and autonomous traveling control in the lawn mowing vehicle 1 described above are performed by a control device 30 shown in FIG. 4, and the control device 30 is composed of a detection unit including a plurality of microcomputers and a control unit. Is done.

The detection units for processing the signals of the sensors and actuators include a vehicle position detection unit 31, a cut boundary detection unit 35, and an obstacle detection unit 36, and the detection units 31, 35 , 36 as a control unit for controlling the travel, a work data storage unit 3 storing a work data map referred to by the travel control unit 37.
8. A vehicle control unit 39 for controlling the vehicle in accordance with an instruction from the traveling control unit 37 is provided. Further, the vehicle control unit 39 drives each mechanism unit of the lawn mower 1 based on the output from the vehicle control unit 39. A control unit 40, a steering control unit 41, and a cutting blade control unit 42 are provided.

Further, the own-vehicle-position detecting section 31 calculates a traveling distance by integrating the vehicle speed detected by the wheel encoder 4, and associates the traveling distance with a change in the traveling direction detected by the geomagnetic sensor 3. The dead reckoning position detecting unit 32 that calculates the running history from the reference point and measures the current position of the vehicle, the CCD camera 8a and the light 8b of the imaging unit 8, and the rotation mechanism unit 10 A sign image pickup control unit 33 that outputs each drive signal for sign image pickup to a rotation drive motor 11 such as a built-in step motor or servo motor, and a video signal from the CCD camera 8a is processed to generate a plurality of signals. Recognizing the sign, the rotation angle signal from the rotation angle sensor 12 attached to the rotation mechanism unit 10 and the measurement from the dead reckoning position detection unit 32 The triangulation position detector 34 identifies the individual marker by comparing the data and the pre-stored position data of each marker, and detects the self-position based on the triangulation principle from the pre-stored marker position data. It is composed of

On the other hand, the cut boundary detecting section 35 processes the signal corresponding to the grass / turf height from the cut boundary detection sensor 7 to detect the grass / turf boundary position. As described above, the cut mark boundary detection sensor 7 includes a sled-shaped plate that moves up and down in accordance with grass and lawn height, and a rotary encoder that detects a rotation angle of a member that supports the sled-shaped plate. If the grass
When the vertical displacement of the sled-shaped plate according to the lawn height is converted into a rotation angle and a detection signal is input from a rotary encoder, the cutting boundary detection unit 35 uses this detection signal to perform grass / grass mowing work. The cut area boundary is detected by identifying the completed area and the unworked area, and the position data is output to the travel control unit 37.

The obstacle detecting section 36 detects an unpredictable obstacle by the non-contact sensors 5a and 5b and the contact sensors 6a and 6b, and outputs a detection signal to the traveling control section 37.

The travel control unit 37 stores work data based on information from the dead reckoning position detection unit 32, the triangulation position detection unit 34, the cut boundary detection unit 35, and the obstacle detection unit 36. The error amount between the current position and the target position is calculated by referring to the map of the section 38 (the running map such as the work contents and the terrain data of the work area where the grass and lawn mowing work is performed), and this error amount is calculated. A travel route instruction and a vehicle control instruction are determined for correction, and output to the vehicle control unit 39.

The vehicle control unit 39 converts an instruction from the traveling control unit 37 into a specific control instruction amount, and converts the control instruction amount into the drive control unit 40, the steering control unit 41, and the cutting blade control unit 42. Output to Thereby, the drive control unit 4
0, the hydraulic motor 13 is driven to generate hydraulic pressure for driving each mechanism of the lawn mowing vehicle 1, and the steering control unit 41
The servo control of a front wheel steering mechanism and a rear wheel steering mechanism, not shown, is performed via a front wheel steering hydraulic control valve 14 and a rear wheel steering hydraulic control valve 15, respectively. The cutting blade mechanism 2 is servo-controlled via the cutting blade control hydraulic control valve 16.

FIG. 5 shows a specific circuit configuration of the vehicle position detecting unit 31. The CPU 50 has a RAM 51 for storing work data, and the positions of signs installed around a specific area to be worked. RO in which data and other fixed data for control and a control program are stored
M52, I / O for input / output of various data and control signals
An O interface 53 is formed around a microcomputer connected via a data bus 54 and an address bus 55. The O interface 53 controls imaging by the CCD camera 8a, processes an image stored in the video memory 65, and recognizes a sign. -The vehicle position is detected by triangulation.

That is, the CPU 50 executes a program for a self-position detection routine shown in FIG. 1 described later, and outputs a control signal from the I / O interface 53 to the motor drive circuit 56 and the light drive circuit 57 to turn on the light 8b. The rotation mechanism 10 is driven by the rotation drive motor 11 to rotate the light 8b and the CCD camera 8a,
An electronic shutter control signal is output to the CCD camera 8a at every set time interval to perform imaging of the entire circumference.

The image picked up by the CCD camera 8a is NT
The video signal is sent to the amplifier 58 as an SC video signal, amplified, and supplied to the synchronization circuit 59 and the AD converter 60, respectively. The synchronization circuit 59 separates the synchronization signal from the video signal, generates a timing signal, and supplies the timing signal to the AD converter 60 and the address control circuit 61.

The AD converter 60 converts the video signal from the amplifier 58 into digital image data in synchronization with the timing signal, and outputs the digital image data to the switching circuit 64 via the data bus 62. The address control circuit 61 generates address data in synchronization with the timing signal and supplies the generated address data to the switching circuit 64 via the address bus 63.

The switching circuit 64 selectively connects one of the data bus 54 and the address bus 55 of the CPU 50 and the data bus 62 and the address bus 63 of the AD converter 60 to the video memory 65. While the address data is being supplied from the address control circuit 61 to the switching circuit 64, the data bus 6 on the AD converter 60 side
2 is connected to a video memory 65 so that image data can be written.
5 is prohibited.

When the supply of the video signal from the CCD camera 8a is stopped and the CPU 50 can access the video memory 65, the image data is read from the video memory 65, and the image data is processed and processed in the work area. After a plurality of surrounding signs are recognized, each sign is identified based on each signal from the geomagnetic sensor 3, the wheel encoder 4, and the rotation angle sensor 12 read through the I / O interface 53, and triangulation is performed. The position of the own vehicle is calculated by the I / O interface 53 and the travel control unit 37 is calculated.
The own vehicle position information is output to.

Hereinafter, for a work area as shown in FIG.
A case where grass and lawn mowing work is performed unattended will be described. In this case, it is assumed that the lawn mowing vehicle 1 has been moved by manned driving from an arbitrary preparation position 70 to a grass / grass mowing work start point 74 in the work area 72 before starting work. Fig. 1 and 2
Is performed autonomously according to the program shown in the flowchart of FIG. Then, after the work is completed, the work is again moved from the work end point 75 to the standby position 78 by manned driving.

In FIG. 6, reference characters PA, PB, PC
Is a sign previously set around the work area 72.

FIG. 2 shows a main control routine executed by the traveling control unit 37. In this main control routine, first, in step S101, a self-position detection routine of FIG. Let the signs PA, PB, PC
When self-position is measured by triangulation,
It is confirmed that the lawn mowing vehicle 1 has reached the lawn mowing work start point 74, and in step S102, the hydraulic control valve 1
The valve 6 is opened to supply hydraulic pressure to the cutting blade mechanism 2, and the cutting blade is operated to start grass and lawn mowing work.

Next, the process proceeds to step S103, where the lawn mowing operation is performed for one.
It is checked whether or not it is the first time, and if it is the first step (first column) of the first operation, the process proceeds to step S104, and if it is the second or subsequent line, the process branches to step S109.

Here, this is the first work, and when the process proceeds from step S103 to step S104, the own position detecting routine is executed again by the own vehicle position detecting unit 31, and the vehicle position and the traveling direction of the own vehicle are determined by triangulation and dead reckoning navigation. After detecting
In the following step S105, the error amount from the current position is determined by referring to the work data storage unit 38 and setting the first (first column) end point position in the work area 72 as the target position.

Next, proceeding to step S106,
Each target steering amount of the front and rear wheels is determined according to the error amount obtained in S105, and in the following step S107, the front wheel steering mechanism via the front wheel steering hydraulic control valve 14, the rear wheel steering hydraulic control valve 15, Each of the rear wheel steering mechanisms is driven and controlled to obtain a target steering angle.

Then, in step S108, it is determined whether or not the lawn mowing vehicle 1 has reached the first (first row) end point position.
If the end point position has not been reached, the aforementioned step S104
Return to and continue grass and lawn mowing work, and when the end point is reached,
Proceeding to step S116, it is determined whether all operations have been completed. In this case, since it is the first operation, the above-described steps are performed.
Returning to S103, it is checked again whether the work is the first work or not. When the work is performed for the second time or later, the process branches to step S109 to follow the work path 73 along the cutting boundary.

That is, when the vehicle body is shifted laterally by the width of the cutting blade in step S109 and moved to the next work position, the cut boundary in the previous work is detected by the cut boundary detection sensor 7 in step S110, and in step S111, Then, an error amount for realizing the set lawn mowing overlap amount is obtained by comparing the mound boundary and the vehicle position.

In the following step S112, step S111
The target steering amounts for the front and rear wheels are determined in accordance with the error amounts obtained in step S113, and in step S113, the front-wheel steering hydraulic control valve 1
4. Front wheel steering mechanism via rear wheel steering hydraulic control valve 15,
Each of the rear wheel steering mechanisms is driven and controlled to obtain a target steering angle.

Thereafter, the process proceeds to step S114, in which the own vehicle position detecting section 31 executes the own position detecting routine to detect the vehicle position and the traveling direction of the own vehicle by triangulation and dead reckoning navigation. It is checked whether 1 has reached the end point position after the second time (from the second column).

If the end point position has not been reached, the process returns from step S115 to step S110 described above to continue the tracing along the cut boundary, and reaches the end point position for the second time or later (from the second column onward). Then, the process proceeds from step S115 to step S116, and it is determined whether or not the grass / turf mowing work of the work area 72 has been completed.

As a result, if the grass / mowing work in the work area 72 has not been completed, the process returns from step S116 to step S103 to continue the work. And the vehicle is stopped.

Next, self-position detection by sign recognition and triangulation by the self-position detection routine of FIG. 1 will be described.

This self-position detecting routine is a routine of the own-vehicle position detecting section 31 which is started by the main control routine of the traveling control section 37 described above.
When the lighting light 8b is turned on via the light drive circuit 57, the motor 11 is turned on via the motor drive circuit 56.
To rotate the imaging unit 8 (the light 8b and the CCD camera 8a) via the rotation mechanism 10 at the set speed.

Next, the process proceeds to step S202, and an imaging time interval in which no blind spot is obtained is obtained from the rotational speed of the CCD camera 8a and the horizontal viewing angle of the CCD camera 8a. Is triggered to capture an image of the surrounding landscape over the entire circumference, and the AD converter 6
At 0, it is converted into a digital signal and written into the video memory 65.

When the writing of the image data into the video memory 65 is completed, the switching circuit 64 operates the CPU 50.
Can access the video memory 65 by
In step S203, the captured image data is read, and a sign is detected by obtaining a feature amount corresponding to the sign from the luminance information, color information, shape, or the like of the read captured image.

That is, each of the markers PA, PB, and PC is a light reflection marker, for example, a retroreflective plate pasted over a predetermined length, to increase the brightness of the sign image pickup portion, binarize the image, and form the marker. After the extraction, each sign can be identified by comparing the position of the present position estimated by dead reckoning with the mark stored in advance. Or,
Further, for example, by setting the markers PA, PB, and PC as markers of different colors, the markers can be extracted and identified from the color information of the captured image. Further, for example, by setting the shapes of the respective markers PA, PB, and PC to be different from each other, and examining whether or not the shape extracted based on the luminance information of the captured image matches the shape of each stored marker. , Individual signs can be identified.

In this case, since the image obtained from the CCD camera 8a has an angle of view in the horizontal and vertical directions,
The sign can be reliably detected without losing the sign due to the inclination of the vehicle or the vibration of the vehicle itself in an uneven terrain or undulating work area.

Next, the process proceeds to step S2O4, in which each image of the lawn mowing vehicle 1 obtained when the image of the lawn mower 1 is obtained from the center of gravity of the recognized sign on the image and the rotation angle signal from the rotation angle sensor 12 attached to the rotation mechanism unit 10. The direction of each sign is calculated from the camera angle, and the angle α formed by the sign PA and the sign PB and the angle β between the sign PB and the PC centering on the own vehicle are calculated and stored in advance for each sign PA. , PB,
When the current vehicle position is calculated from the position of the PC by a well-known triangulation method, the calculated self-position data is used in step S2.
At 05, it is sent to the travel control unit 37 and returns to step S202.

That is, as shown in FIG. 7, in the X, Y coordinate system having the marker PA as the origin, the distance from the marker PA (coordinate origin) to the center position of the vehicle is determined based on each data stored in the ROM 52 in advance. The distance L and the angle θ1 between the line connecting the center of the vehicle from the marker PA (coordinate origin) and the line connecting the markers PA and PB are determined by the following equations (1) and (2), and the vehicle position ( X1, Y1) can be obtained by the equations (3) and (4). L = L1 × sin (α + θ1) / sinα (1) θ1 = atn (−L2 × sinα × sin (θB + α + β) / (L1 × sinβ + L2 × sinα × cos (θB + α + β))) (2) L1; Distance between PBs L2; distance between markers PB and PC θB; angle between line connecting markers PA and PB and line connecting markers PB and PC θA; angle of line connecting markers PA and PB to X axis X1 = L × cos (θA−θ1) (3) Y1 = L × sin (θA−θ1) (4)

[0046]

As described above, according to the present invention, the image pickup means is rotated via the rotation mechanism provided on the autonomous traveling work vehicle, and the time set based on the rotation speed and the image pickup angle of view of the image pickup means. Since the surrounding images including the sign are captured at each interval, and the sign is recognized by calculating the feature amount of the sign from the plurality of captured images, the inclination of the vehicle or the vibration of the vehicle itself in an area having irregular terrain or undulations Thus, excellent effects can be obtained, such as being able to reliably recognize the sign by eliminating the influence of the marker and accurately detecting the self-position.

[Brief description of the drawings]

FIG. 1 is a flowchart of a self-position detection routine.

FIG. 2 is a flowchart of a main control routine.

FIG. 3 is a schematic explanatory view showing the appearance of a lawn mower.

FIG. 4 is a block diagram of a control system.

FIG. 5 is a circuit configuration diagram of a vehicle position detection unit.

FIG. 6 is an explanatory diagram showing a traveling route and a work area.

FIG. 7 is an explanatory diagram of self-position detection by triangulation.

[Explanation of symbols]

 1 lawn mowing vehicle (autonomous traveling vehicle) 8a CCD camera (imaging means) 10 rotating mechanism PA, PB, PC sign

Continuation of front page (56) References JP-A-5-46240 (JP, A) JP-A-56-1304 (JP, A) JP-A-5-189033 (JP, A) JP-A-3-171304 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G05D 1/02

Claims (1)

(57) [Claims] 1. A method for detecting a self-position of an autonomous traveling vehicle by recognizing a plurality of signs installed around a specific work area and detecting a self-position by triangulation. A rotation mechanism for rotating the image pickup means as possible, and taking an image of the surrounding area including the sign by the image pickup means at each time interval set from the rotation speed of the rotation mechanism section and the imaging angle of view of the image pickup means A self-position detecting method for an autonomous traveling work vehicle, wherein a feature amount of the sign is obtained from a plurality of captured images to recognize the sign.