JPH069011B2 - Travel control system for automated guided vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention is based on image pickup means for repeatedly picking up an image of a work site in front of a vehicle body in a two-dimensional direction, and based on image pickup image information of the image pickup means. First boundary detection means for detecting a first boundary between an unprocessed work site and a processed work site in the vehicle body width direction, and an unprocessed work site and a process in the vehicle body front-rear direction based on imaged image information of the imaging means. Second boundary detection means for detecting the second boundary with the completed work site, distance detection means for detecting the travel distance of the work vehicle, and travel distance of the work vehicle is set to a value shorter than the length of the first boundary. If the distance is smaller than the set distance, the first boundary detecting means is operated, and if the traveling distance is larger than the set distance, the second boundary detecting means is operated, Based on the detection information of the detection means, the first The distance from the current position of the work vehicle to the second boundary is calculated based on the information of the detection boundary selecting means for selectively operating the field detecting means and the second boundary detecting means and the second boundary detecting means. Distance calculation means, steering control means for performing steering control so that the work vehicle automatically travels along the first boundary based on the detection information of the first boundary detection means, the distance calculation means, and the distance detection. When it is determined that the work vehicle has reached the second boundary based on the information of the means, each of the turn control means for moving toward the starting end portion of the first boundary corresponding to the next work stroke. The present invention relates to a travel control device for an automated guided vehicle equipped with the.

[Conventional technology]

The traveling control device for an automatic traveling work vehicle of the above-mentioned type, as the work vehicle automatically travels along the boundary between the unprocessed work site and the processed work site, and reaches the end portion of one work stroke. The vehicle is configured to control the traveling of the work vehicle based on the image information obtained by imaging the front side in the traveling direction of the vehicle body so that the vehicle automatically turns toward the start end of the next work stroke.

Therefore, it is necessary to detect the second boundary on the end side in order to turn toward the start end of the next work stroke as it reaches the end end of one work stroke. If the first boundary and the second boundary on the terminating side are detected, the processing becomes complicated, and it becomes difficult to control in accordance with the traveling speed of the work vehicle. As you reach the set distance, which is also set to small,
The second boundary on the terminal side is detected.

However, conventionally, even after the second boundary on the terminal side is detected, until the detected second boundary on the terminal side is reached,
The steering control is performed based on the detection information of the first boundary on the work stroke side.

[Problems to be solved by the invention]

If the steering control is continuously performed until the second boundary on the terminating side is reached as in the above-described conventional art, the vehicle travels to the detected second boundary due to the meandering of the vehicle body due to the steering control. There is fear.

If the mileage to the second boundary is erroneously detected, there is a risk that the start position of the turn for moving to the next work stroke may be wrong and the next work stroke may not be properly entered.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to smoothly start the movement to the next work process.

[Means for solving problems]

The characteristic configuration of the traveling control device for the automated guided vehicle according to the present invention is as follows.

That is, the steering control means is configured to proceed straight after traveling the set distance or after detecting the second boundary in a state where the steering is stopped until the second boundary is reached. And its action and effect are as follows.

[Action]

In other words, after traveling to the point where the second boundary on the end side of the work stroke is detected or after detecting the second boundary, the vehicle is moved straight while the steering is stopped until the second boundary is reached. It is possible to reduce the detection error of the traveling distance for determining that the traveling has stabilized and the detected second boundary has been reached.

〔The invention's effect〕

Therefore, the detection that the detected second boundary has been reached becomes accurate, and the turn for moving to the next work stroke can be accurately performed, and after the turn,
We were able to properly approach the next work process.

In addition, since the vehicle goes straight in a steering stopped state until it reaches the second boundary, it is a boundary between the unprocessed work site and the treated work site, which is the first boundary in the next work stroke formed with the traveling of the work vehicle. Is improved, the detection accuracy in the boundary detection in the next work stroke is improved, and thus the followability to the boundary in the steering control can be improved.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 6, a pair of left and right front wheels as steering wheels
(1) and a pair of left and right rear wheels (2), a lawn mowing device (3) is vertically movably suspended on the lower abdomen of a vehicle body, and is used for mowing work of lawn and weeds (V) Is configured.

Then, the image sensor (S ₁ ) as an imaging means for imaging the work site on the front side in the traveling direction of the machine body over the two-dimensional direction,
It is attached to the front part of the machine body so that the work site on the front side with respect to the machine body is directed obliquely downward.

If the image pickup field of view of the image sensor (S ₁ ) is further explained, the work vehicle (V) is uncut as unprocessed work land.
In a state in which the first boundary (L ₁ ) in the vehicle width direction between the (B) and the already cut land (C) as the treated work land is in a proper state, the first boundary (L ₁ ) However, it is arranged so as to be positioned at the center of the imaging visual field in the lateral direction.

Explaining the structure of the work vehicle (V), as shown in FIG. 1, a steering hydraulic cylinder (4) for operating the front wheel (1) and a control valve (5) for the steering hydraulic cylinder (4) are provided. A continuously variable transmission (6) is linked to an engine (E), and a transmission motor (7) is a transmission arm of the transmission (6).
Linked to (8).

However, the transmission (6) is linked to both the front and rear wheels (1), (2), and is configured as a so-called four-wheel drive type work vehicle.

A rotation speed sensor (S that outputs a preset number of pulse signals per unit rotation speed) is driven to rotate by the output of the transmission (6).
₂ ) is provided, and the work vehicle is based on the pulse signal.
It is configured so that the traveling distance of (V) can be detected. That is, the rotation speed sensor (S ₂ ) corresponds to the distance detecting means for detecting the traveling distance of the work vehicle.

A steering angle detecting potentiometer (R ₁ ) for detecting the steering angle of the front wheel (1), and the transmission.
A vehicle speed detection potentiometer (R ₂ ) for indirectly detecting the vehicle speed by detecting the operation state of (6) is provided,
Those detection information, information of the boundary (L ₁ ) detected based on the image pickup information of the image sensor (S ₁ ), detection information of the rotation speed sensor (S ₂ ), various traveling controls preset and stored A control device (9) using a microcomputer is provided for controlling the work vehicle (V) to automatically travel along the boundary (L ₁ ) based on the information.

In the figure, (H) is a steering handle for boarding operation,
(R ₀ ) is a potentiometer for detecting its operation position, and (10) is a speed change pedal for boarding and manipulating.

However, a first boundary detecting means (100) for detecting the first boundary (L ₁ ) by image-processing the image pickup information of the image sensor (S ₁ ).
A), the end of the work process, that is, uncut land in the front-back direction of the vehicle (B)
Second boundary detecting means (100B) for detecting a second boundary (L ₂ ) between the ground and the already cut land (C), and the first boundary detecting means (100B) based on the traveling distance detected by the rotation speed sensor (S ₂ ). 100A) and the second boundary detecting means (100B) for selectively operating the detection boundary selecting means (10
1), distance calculation means (102) for calculating a distance to the second boundary (L ₂ ), steering control so that the work vehicle (V) automatically travels along the first boundary (L ₁ ). Steering control means (103), and turn control means (1) for moving the work vehicle (V) to the start end of the next work stroke as the work vehicle (V) reaches the second boundary (L ₂ ).
04) Each means will be configured using the control device (9).

Explaining the automatic running of the work vehicle (V), as shown in FIG. 7, a portion extending from one side to the opposite side of a square uncut land (B) surrounded by already cut land (C). As one working stroke, the working vehicle (V) is
The steering control is performed based on the detection information of the first boundary detection means (100A) so that the vehicle automatically travels along the first boundary (L ₁ ) between the (B) and the already-cut land (C). And a second boundary detecting means
(100B), the second boundary (L ₂ ) on the end side of one work stroke, that is, the opposite end of the uncut land (B), and the beginning of the next work stroke that intersects the work stroke By repeating the automatic turn toward the section, the lawn mowing work within a predetermined range is automatically performed.

If the description is added based on the flowchart shown in FIG. 2, when the traveling is started, the image sensor (S _{1 is} moved every time the vehicle travels a set distance based on the detection information of the rotation speed sensor (S ₂ ). ) Is performed, and the work vehicle (V) uses the first information based on the information detected from the imaging information.
The steering is controlled so that the vehicle automatically travels along the boundary (L ₁ ).

That is, the process for controlling the steering so that the work vehicle (V) automatically travels along the first boundary (L ₁ ) is based on the detection information of the first boundary detecting means (100A). It corresponds to the steering control means (103) that operates.

Then, based on the detection information of the rotation speed sensor (S ₂ ),
Based on whether or not the vehicle has traveled to a set distance set to a value shorter than the length of one work stroke, that is, the length of the first boundary (L ₁ ), it is determined whether or not the end is near, and approaches the end. Along with this, the processing of end detection for detecting the second boundary (L ₂ ) on the end side is performed while moving straight in a steering stopped state,
Based on the detection information, the distance from the current position of the work vehicle (V) to the end position is calculated, and the rotation speed sensor (S ₂ )
As the vehicle travels to the determined end position on the basis of the detection information, the turn is made toward the next work stroke based on the turn pattern set and stored in advance.

However, the set distance for starting the processing of the end detection has an error in the traveling distance detected by the rotation speed sensor (S ₂ ) due to meandering of the working vehicle (V) due to steering control, slip of wheels, etc. Even if it occurs, the second boundary (L ₂ ) is
So as not to be outside the imaging field of view (S _1), it will be set in advance based on the installation height and viewing direction of the center of the inclination or the like of the image sensor (S _1).

In addition, based on the detection information of the rotation speed sensor (S ₂ ), as the work vehicle (V) approaches the end, the first boundary (L ₁ )
Detection boundary selection means for selectively operating the first boundary detection means (100A) and the second boundary detection means (100B) in the process of switching from the state of detecting the second boundary (L ₂ ) to the state of detecting the second boundary (L ₂ ). This corresponds to (101), and the process of turning toward the next work stroke based on the preset and stored turn pattern corresponds to the turn control means (104).

After the turn, for example, it is judged whether or not the work is completed based on whether or not the travel has traveled a preset number of strokes, or whether or not the traveled distance has been set, and the work is not completed. In this case, each process from the boundary detection process described above is repeated, and when the work is completed, the work vehicle (V)
Will be stopped and the whole process will be ended.

Next, the first boundary detecting means (100A) will be described based on the flowchart shown in FIG.

However, the boundary detection process described below is performed in
This is done by using the phenomenon that (C) looks brighter than the uncut area (B).

Along with the activation of the boundary detection process, the image sensor (S ₁ ) performs the image capturing process, and the image capturing information is input to the control device (9) and quantized, after which a fine brightness change is performed. Smoothing to remove

After the image pickup information is smoothed, a differentiation process is performed based on the difference in brightness between adjacent pixels in the machine body width direction, that is, the x-axis direction.

If the differentiation process is further described, as shown in FIG. 4, the 8 pixels adjacent to the target pixel (e) to be processed are adjacent to each other.
Brightness in the x-axis direction on the image corresponding to the lateral direction of the fuselage is calculated based on the following formula (i) using a mask for 3 × 3 pixels covering 9 pixels including pixels (a to d, f to i). Differential value
The process of obtaining (SX) is performed for each pixel arranged in the two-dimensional direction.

SX (x, y) ＝ (a + d + g)-(c + f + i) …… (i) However, in this differentiation processing, the boundary (L ₁ ) with respect to the work vehicle (V) is Based on which side it is located,
The sign of the differential value (SX) is discriminated, and only the value having one of the positive and negative signs is used.

That is, in the formula (i), the brightness of the pixel located on the right side is subtracted from the brightness of the pixel located on the left side of the image, so that when the left side is brighter, the differential value (SX ) Is a positive value, and is negative if the right side is brighter.

Then, binarization is performed so as to extract only the pixels whose absolute value of the differential value (SX) is equal to or larger than a preset threshold value, thereby extracting the pixels at the location where the brightness change is large.

Next, using the Hough transform process, for each binarized pixel, a large number of straight lines divided at each set angle passing through the pixel are calculated in the polar coordinate system based on the following equation (ii). The distance (ρ) from the origin and the slope (θ) with respect to the reference axis are calculated as values, and the same frequency is taken in a two-dimensional histogram,
From the histogram, one straight line with the maximum frequency is
Distance from the origin (ρ) and inclination with respect to the reference axis (θ)
Ask as.

ρ = x · cos θ + y · sin θ (ii) Then, based on the obtained values (ρ) and (θ), the deviation in the machine width direction from the position based on the center of the imaging field of view of the image sensor (S ₁ ) ( χ) and the inclination (ψ) with respect to the y-axis passing through the center thereof are obtained as position information of the straight line corresponding to the boundary (L ₁ ) (see FIG. 5 (a)).

However, since the imaging direction of the image sensor (S ₁ ) is directed downward toward the front side in the aircraft traveling direction, the position change of the boundary (L ₁ ) in the imaging field of view is Inversely proportional to the distance, the distance becomes smaller.

Therefore, the deviation (χ) and the inclination (ψ) with respect to the actual boundary (L ₁ ) with respect to the center of the imaging field of view are corrected to have values according to the imaging distance.

Therefore, the series of processes for detecting the boundary described above corresponds to the first boundary detecting means (100A).

Explaining the second boundary detecting means (100B), since the change in brightness at the second boundary (L ₂ ) on the terminal end side becomes large in the vertical direction on the image, the first boundary detecting means (1
In the formula (i) in (00A), by changing the differentiating direction so as to subtract the brightness between the pixels arranged in the vertical direction, and performing the same processing as the first boundary detecting means (100A), The second boundary (L ₂ ) will be detected.

That is, the straight line corresponding to the second boundary (L ₂ ) is x on the image.
Since it is a straight line toward the axial direction, the deviation (χ) from the center of the field of view is
It will be detected as a value corresponding to the distance to (L ₂ ) (see FIG. 5B).

However, at the time of detecting the second boundary (L ₂ ), as in the case of detecting the first boundary (L ₁ ), the image sensor (S ₁ ) is to pick up an image while looking down diagonally at the work site. Because,
The position change of the boundary (L ₂ ) in the imaging visual field is inversely proportional to the imaging distance, and becomes smaller as the distance increases. Therefore, from the position of the second boundary (L ₂ ) on the image, based on the mounting height of the image sensor (S ₁ ) with respect to the vehicle body, the inclination of the center of the visual field, etc., the current state of the work vehicle (V) on the ground is actually measured. The distance from the position to the second boundary (L ₂ ) will be calculated. That is,
Using the first boundary detecting means (100A), the second boundary (L
₂ ) is detected and the end detection is performed, and based on the detection position of the second boundary (L ₁ ) in the y-axis direction on the image,
The process of obtaining the distance to the second boundary (L ₂ ) on the actual ground is performed from the current position of the work vehicle (V) to the second boundary (L ₂ ).
Distance calculation means for calculating the distance to reach (L ₂ ) (102)
Will correspond to.

If the steering control is further described, the deviation (χ) and the inclination (ψ) with respect to the center of the imaging visual field detected by the first boundary detection means (100A), and the steering angle detection potentiometer (R ₁ ) Based on the current steering angle (θ) of the front wheel (1) detected at Will be set.

However, α ₁ , α ₂ , and α ₃ are preset constants based on the characteristics of the steering system.

[Another embodiment]

In the above-described embodiment, the first boundary detecting means (100A) and the second boundary detecting means (100B) are used for the respective boundary (L
_The case where the straight line corresponding to ₁ ) and (L ₂ ) is obtained has been described as an example, but the specific configuration can be variously changed.

In the above embodiment, the case where the front wheel (1) is steered by the two-wheel steering system is shown as an example, but both the front and rear wheels (1) and (2) are separately operated. The steering wheel can be operated, for example, the inclination (ψ) is corrected by using a four-wheel steering type in which the front and rear wheels (1) and (2) are turned in opposite directions to turn the vehicle body lateral width. The deviation of the direction (χ) can be corrected by using the parallel steering type in which the front and rear wheels (1) and (2) are turned in the same direction and moved in parallel, or the deviation from the inclination (ψ) is corrected. Depending on (χ), the steering angles of the front and rear wheels (1) and (2) may be different, and both the inclination (ψ) and the deviation (χ) may be corrected at the same time. Steering control means (1
The configuration of each part, such as the specific configuration of 03), can be variously changed according to the configuration of the work vehicle to which the present invention is applied.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of a traveling control device for an automated guided vehicle according to the present invention, and FIG. 1 is a block diagram showing a control configuration, and FIG.
Figure is a flow chart of control operation, Figure 3 is a flow chart of boundary detection, Figure 4 is an explanatory view of differentiation processing, and Figure 5 (a)
(B) is an explanatory view of boundary detection, FIG. 6 is an overall side view of the work vehicle, and FIG. 7 is an explanatory view of the work site. (S ₁ ) ... Imaging means, (S ₂ ) ... Distance detection means, (B) ... Unprocessed work site, (C) ... Processed work site, (L ₁ ) ... First boundary, ( L ₂ ) ... second boundary, (100A) ... first boundary detecting means,
(100B) ... second boundary detection means, (101) ... detection boundary selection means, (102) ... distance calculation means, (103) ... steering control means, (104) ... turn control means.

Claims (1)

[Claims] 1. An image pickup means (S ₁ ) for repeatedly picking up an image of a work site on the front side in the traveling direction of a vehicle body in a two-dimensional direction, and the image pickup means.
First boundary detection means (L ₁ ) for detecting the first boundary (L ₁ ) between the unprocessed work site (B) and the processed work site (C) in the lateral direction of the vehicle body based on the captured image information of (S ₁ ). 100A), based on the imaged image information of the image pickup means (S ₁ ), the unprocessed work site in the front-back direction of the vehicle body
_Second detecting the second boundary (L ₂ ) between (B) and the treated work site (C)
Boundary detection means (100B), distance detection means (S ₂ ) for detecting the travel distance of the work vehicle (V), and a value at which the travel distance of the work vehicle (V) is shorter than the length of the first boundary (L ₁ ). If it is smaller than the set distance set to, the first boundary detecting means (100A) is activated, and if the traveling distance is larger than the set distance, the second boundary detecting means (100A) as actuate 100B), said distance detecting means (on the basis of the detected information S _2), the first boundary detecting means (100A) and the second boundary detecting means (100B)
Detection boundary selection means (101) for selectively operating and,
Based on the information of the boundary detection means (100B), the work vehicle (V)
Distance calculating means (102) for calculating the distance from the current position to the second boundary (L ₂ ) and the first boundary detecting means (10)
0A), the work vehicle (V) detects the first boundary
(L ₁ ) based on the information of the steering control means (103) for steering control so that the vehicle automatically travels along the line (L ₁ ), the distance calculation means (102) and the distance detection means (S ₂ ), When it is determined that V) has reached the second boundary (L ₂ ), the turn control means (104) for moving toward the starting end portion of the first boundary (L ₁ ) corresponding to the next work stroke. ) Is a traveling control device for an automatic traveling work vehicle, each of which, the steering control means (103), after traveling the set distance or after detecting the second boundary (L ₂ ), A traveling control device for an automatic traveling work vehicle, which is configured to proceed straight with the steering stopped until reaching the second boundary (L ₂ ).