Automatic running work vehicle

Detailed Description of the Invention

The present invention relates to an autonomous working vehicle that is equipped with a sensor that detects the boundary between untreated work land and treated work land, and a direction sensor that detects the vehicle's traveling direction, and is provided with control means that steers both the front and rear wheels of the vehicle so that it can automatically travel along the boundary, and the control means is configured to correct the direction by direction correction steering that operates the front wheels and the rear wheels at different angles when the difference between the direction detected by the direction sensor and a reference direction is greater than allowable, and to correct the lateral deviation by parallel movement steering that operates the front wheels and the rear wheels by a predetermined angle in the same direction when the sensor that detects the boundary detects a lateral deviation between the vehicle body and the boundary. Such an autonomous work vehicle corrects lateral deviations using parallel movement steering, which does not change the vehicle's direction of travel. This allows the vehicle to accurately follow and travel along the boundary, compared to steering, which changes the vehicle's direction of travel even when correcting lateral deviations, and reduces the frequency of steering operations, providing advantages in terms of durability. Incidentally, when the control means performs azimuth correction and lateral deviation correction, it is conceivable to give priority to lateral deviation correction by parallel movement steering over azimuth correction by azimuth correction steering, so that azimuth correction is performed by the azimuth correction steering only when the sensor that detects the boundary does not detect lateral deviation between the vehicle body and the boundary. However, if lateral deviation correction is given priority over azimuth correction, if the vehicle body is tilted significantly relative to the longitudinal direction of the boundary, lateral deviation correction by parallel steering may not be performed quickly, or in some cases, lateral deviation correction may not be possible at all. To explain further, since the parallel steering operates the front and rear wheels in the same direction by a predetermined angle, if the inclination of the vehicle body relative to the longitudinal direction of the boundary and the predetermined angle of the parallel steering are the same, the vehicle body will simply travel along the boundary with a constant amount of lateral deviation from the boundary. Therefore, as can be inferred from this, if the inclination of the vehicle body relative to the longitudinal direction of the boundary is large, problems will arise in which the lateral deviation cannot be quickly corrected or the lateral deviation cannot be corrected at all. The present invention has been made in view of the above circumstances, and aims to make it possible to appropriately correct lateral deviation. A characteristic configuration of the self-driving work vehicle according to the present invention is that the control means is configured to give priority to correcting orientation using the orientation correction steering over correcting lateral deviation using the parallel translation steering, so that lateral deviation correction is performed using the parallel translation steering only when the difference between the orientation detected by the orientation sensor and the reference orientation is within an allowable error, and the actions and effects thereof are as follows: In other words, azimuth correction by azimuth correction steering is given priority over lateral deviation correction by parallel movement steering, and lateral deviation correction by parallel movement steering is performed only when the difference between the azimuth detected by the azimuth sensor and the reference azimuth is within the tolerance, that is, when the inclination of the vehicle body relative to the longitudinal direction of the boundary is small. Therefore, by rationally determining the priority order between azimuth correction and lateral deviation correction, it is possible to properly correct lateral deviation even if the vehicle body is tilted significantly relative to the longitudinal direction of the boundary, thereby avoiding the occurrence of the above-mentioned problems and making it possible to more accurately follow and travel along the boundary. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in Figure 1, a lawnmower 4 equipped with a disk-type cutting blade is suspended so as to be movable up and down in the middle of a vehicle body 1 configured so that both the front wheels 2, 2 and the rear wheels 3, 3 can be steered. In addition, tracing sensors A, A are provided to detect the boundary L between unmowed land B, which is an untreated work area, and already-mowed land C, which is a treated work area, as described below, and a geomagnetic sensor 5 is provided as a direction sensor to detect the traveling direction θ of the vehicle body 1, and is configured to determine direction by detecting the intensity of the geomagnetic field. Thus, a lawnmower is configured as an autonomous work vehicle. Based on the boundary L detected by the tracing sensor A and the traveling direction θ detected by the geomagnetic sensor 5, both the front wheels 2, 2 and the rear wheels 3, 3 are steered to automatically correct the traveling direction. The tracking sensor A is composed of two optical sensors S arranged side by side in the left and right directions of the vehicle body 1.₁,S₂This optical sensor S₁,S₂As shown in FIG. 2, U-shaped sensor frames 6, 6 are fixed to a sensor mounting frame 7 provided on the lawn mower 4, and light emitting elements P are respectively mounted on the inner opposing surfaces of the sensor frames 6.₁and photodetector P₂are provided as a pair, and this light emitting element P₁and photodetector P₂The sensor A is configured to detect the presence or absence of grass introduced as the vehicle body 1 travels between the grass and the uncut land, thereby determining the boundary between the uncut land and the cut land.₁,S₂The sensor may be of any type, whether contact or non-contact, and may be configured using any type of sensor. A control system for automatically steering the front wheels 2, 2 and the rear wheels 3, 3 based on the detection signals of the tracking sensor A and the geomagnetic sensor 5 configured as described above will now be described. As shown in FIG. 3, the control system is configured with a control device 8 whose main part is made up of a microcomputer, and an optical sensor S constituting the scanning sensor A.₁,S₂and the signal from the geomagnetic sensor 5 are input.₁,S₂Based on the detection signals from the front wheels 2, 2 and the rear wheels 3, 3, the control signals for driving the electromagnetic valves 11, 12 that operate the hydraulic cylinders 9, 10, respectively, which act as actuators for steering the front wheels 2, 2 and the rear wheels 3, 3, are calculated and output. That is, the control means for steering both the front wheels 2 and the rear wheels 3 so as to automatically travel along the boundary L is configured using the control device 8. The control device 8 is configured to calculate the difference between the detected azimuth θ by the azimuth sensor 5 and the reference azimuth θ₀When the difference between the above is larger than the tolerance K, the direction is corrected by steering the front wheels 2 and the rear wheels 3 to different angles, and when the tracking sensor A, which detects the boundary, detects a lateral deviation between the vehicle body 1 and the boundary L, the lateral deviation is corrected by parallel movement steering, which operates the front wheels 2 and the rear wheels 3 by a predetermined angle in the same direction. Furthermore, the difference between the detected direction θ by the direction sensor 5 and the reference direction θ₀In order to correct lateral deviation by parallel translation steering only when the difference between the azimuth and the horizontal axis is within the tolerance K, the azimuth correction by the azimuth correction steering is given priority over the lateral deviation correction by parallel translation steering. To explain further, when the tracing sensor A detects the boundary L, that is, when the optical sensor S on the outside of the vehicle body 1₁detects the already cut land C and the optical sensor S inside the vehicle body 1₂When the vehicle is in a state where it detects uncut land B, the front wheels 2, 2 and rear wheels 3, 3 are returned to a neutral state, and control is performed to move the vehicle body 1 straight ahead. On the other hand, the scanning sensor A detects that it has deviated from the boundary L, that is, the two optical sensors S₁,S₂When both of them detect the uncut land B or the cut land C, the detected direction θ by the geomagnetic sensor 5 and the reference direction θ₀4, it is determined whether the vehicle body 1 is displaced parallel to the boundary or obliquely, and the steering angle θ of the front wheels 2, 2 and the rear wheels 3, 3 corresponding to the displaced state is determined._F,i_RThe driving direction is corrected by calculating each of these. That is, the detected direction θ and the reference direction θ₀If the difference between these is within the tolerance K, the steering angles θF and θR of the front and rear wheels 2 and 3 are steered at a predetermined angle S in the same direction opposite to the direction of deviation from the boundary L detected by the tracing sensor A, thereby moving the vehicle body 1 in parallel, thereby performing lateral deviation correction control to return the vehicle body 1 to the boundary L. On the other hand, if the difference between the detected heading θ and the reference heading θo exceeds the tolerance K, the steering angle θF of the front wheels 2, 2 is offset by a predetermined amount (α) from the predetermined angle S to an angle (S±α), and the detected heading θ is adjusted to the reference heading θ₀The azimuth correction is controlled so as to approach the target. However, R in Figure 3₁,R₂are potentiometers for feeding back the actual steering angles of the front and rear wheels 2, 3 to the control device 8, and 13 is a distance sensor configured to generate one pulse per unit distance to detect the distance traveled by the vehicle body 1 when performing the outer perimeter teaching work to detect the reference direction θo and the range of uncut land B where mowing work will be performed. FIG. 5 is a flow chart showing the operation of the control device 8 regarding the steering control explained above, and FIG. 6 is a flow chart showing the operation of the control device 8 regarding the reference heading θ₀and the length of the two sides of the working range (l_A),(l_C) is a flowchart showing the operation during outer circumference teaching that automatically calculates the outer circumference.

[Brief explanation of the drawings]

The drawings show an embodiment of an autonomous working vehicle according to the present invention, with Fig. 1 being an overall plan view of the lawnmower, Fig. 2 being a front view of the main parts of the tracking sensor, Fig. 3 being a block diagram of the control system, Fig. 4 being an explanatory diagram of how the vehicle deviates from the boundary, and Figs. 5 and 6 being flow charts showing the operation of the control device. 1......Vehicle body, 2......Front wheel, 3......Rear wheel, 5......Orientation sensor, 8......Control means, A......Sensor for detecting boundary, B......Unprocessed work area, C......Processed work area, L......Boundary, θ......Detected orientation, θ₀......reference bearing.