JPH06276808A - Automatic steering controller of working vehicle - Google Patents

Abstract

PURPOSE:To prevent an automatically traveling working vehicle from colliding with an obstruction in a guide passage, the automatically traveling working vehicle being steered and controlled so as to follow a guide cable. CONSTITUTION:Usually, an AC electric field generated from a guide cable 27 is detected with magnetic sensors 26a,26b mounted on a working vehicle 1, and the working vehicle 1 is steered and controlled approximately along the guide cable 27. An ultrasonic sensor 37 for detecting an obstruction, etc., is laterally rotatably disposed on the working vehicle 1. A controller for executing an obstruction-avoiding control in preference to the steering control of the working vehicle along the guide cable on the detection of the obstruction is disposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for automatically steering a work vehicle such as an agricultural work machine so as to follow a guide cable laid along a guide path.

[0002]

2. Description of the Related Art Conventionally, in an automatic traveling type chemical sprayer (speed sprayer) or the like in an orchard or the like, an alternating current is applied to an induction cable buried in the ground along a work route (guide route), The change in the strength of the AC magnetic field generated from this induction cable is detected by a magnetic sensor such as a pair of left and right pickup coils mounted on the front part of the traveling vehicle,
The difference between the output values (voltage values) of the pair of left and right magnetic sensors corresponding to the magnitude of the lateral deviation of the traveling vehicle with respect to the guide cable is calculated to determine the magnitude of the lateral deviation (deviation amount) and the lateral deviation direction ( (Right or left discrimination) is obtained, and steering control is performed by changing the direction of the steered wheels in the traveling vehicle so that the traveling vehicle travels along the guide cable based on these detection results (actual). (See Kaihei 2-84909).

[0003]

When steering is controlled along the guide cable in this way, even if another obstacle is present in the guide path, it cannot be sensed. When another obstacle is present in the guide route after laying the vehicle, there is a problem that steering cannot be performed to avoid it.

In order to solve this problem, in Japanese Patent Laid-Open No. 60-258612 as another prior art, a plurality of ultrasonic sensors are provided on the body of a chemical sprayer (speed sprayer), and the ultrasonic sensors It is proposed that the distance between the pair of right and left standing trees and the vehicle body is determined based on the detection result, and steering control is performed so that the vehicle passes between the pair of left and right standing trees.

However, there is a limit to the detection range of the ultrasonic sensor, especially the measurable distance range. further,
When trees are erected at intervals such as a row of trees, it is difficult to determine whether the tree is a guide route or an obstacle. Therefore,
If the steering control is performed only by the detection by the ultrasonic sensor, there is a problem that the steering control is likely to meander. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a steering control device that compensates for the drawbacks of both of the above prior arts and that can perform steering control accurately and quickly with two types of sensors.

[0006]

In order to achieve this object, the present invention provides a control means for detecting an alternating electric field from an induction cable with a magnetic sensor and steering the induction cable substantially along the induction cable. In the work vehicle, the work vehicle is provided with an ultrasonic sensor for detecting obstacles and the like, and means for executing obstacle avoidance control by detection of the ultrasonic sensor is given priority over steering control along the guide cable. It is a thing.

[0007]

EXAMPLES Next, examples in which the present invention is applied to a system for guiding an automatic traveling type chemical sprayer (speed sprayer) will be described. A speed sprayer has a driving operation section 2 provided with a handle 3 on the front side of a work vehicle 1, and the work vehicle 1 is provided with a chemical liquid tank 4 having a substantially L shape in a plan view and a spray section 5 at the rear thereof. ing.

The spraying section 5 is equipped with a large number of spray nozzles 6 facing the outer peripheral surface of the work vehicle 1 except the lower surface thereof at an appropriate interval toward the radially outward direction, and a blower 7 for sending air outwardly at the radius.
The spray nozzles 6 can be spray-controlled so as to perform spraying work in three sections or two sections on the left and right of the work vehicle 1 and the upper surface. Reference numerals 8 and 8 are left and right front wheels,
Reference numerals 9 and 9 denote left and right rear wheels, and these four wheels are of a so-called four-wheel drive type in which power from the engine 10 is transmitted via the traveling speed change mechanism 11 to be driven.
Blower 7 from the power from 0 through another power transmission mechanism 12
And the power pump 13 for the spray nozzle 6
Drive.

The steering device 14 with the steering wheel 3 is a power steering mechanism 15 including a mechanical or hydraulic system as shown in FIG. 3. The power steering mechanism 15 is a double-acting hydraulic cylinder 17 in a hydraulic circuit 16. When actuated and the hydraulic cylinder 17 extends, the rear wheels 9, 9 are turned to the left through the bell crank 18 having a W-shape in plan view, and the connecting rod 19 and the bell crank 20 having a V-shape in plan view are used. By changing the front wheels 8 and 8 to the left (when the hydraulic cylinder 17 is contracted, both the front and rear wheels are changed to the right), the front and rear four wheels can be turned to the left and right in the same direction. It is a wheel steering type.

The hydraulic circuit 16 is shown in FIG.
Is an electromagnetic solenoid type control valve for the hydraulic cylinder 17 for automatic steering, reference numeral 29 is a control valve for controlling the hydraulic cylinder 30 for running brake and clutch operation, and these are hydraulic oil from the hydraulic pump 22. In the case of feeding, it is connected to a hydraulic pipe 31 branched from an upstream side of the control valve 23 for manual steering.

During manual steering, the hydraulic motor 21 that sends the oil discharge amount through the control valve 23 in proportion to the turning angle of the handle 3 transfers oil to the double-acting hydraulic cylinder 17 attached to the steering mechanism 15. During automatic steering control, hydraulic oil is sent from the hydraulic pump 22 to the hydraulic cylinder 17 via the electromagnetic solenoid type control valve 28. Reference numeral 25 is a steering angle sensor such as a potentiometer capable of detecting the steering angle of the front wheels 8. In this case, the average value of the orientation angles of the left and right wheels may be obtained and detected.

The front wheels and the rear wheels may be connected via separate hydraulic cylinder type power steering mechanisms so that the front wheels and the rear wheels can be individually steered. On the lower surface of the work vehicle 1, a pair of left and right magnetic sensors 2 is provided on the front portion.
6a and 26b are provided. This magnetic sensor 26a, 26
b may be a pickup coil formed by winding a conductor in a coil shape, or may be a Hall element, a Hall IC, a magnetoresistive element, or a magnetic transistor, and is connected to the induction cable 27 by an AC current generator 53 described later. The strength of the AC magnetic field generated around the induction cable 27 can be detected by the applied AC current having an appropriate frequency. The guide cable 27 is laid in a groove formed along the guide route which is the working route of the orchard, or is buried underground.

A direct current may be applied to the induction cable 27 in a pulsed manner, or a pulse signal may be added to the direct current to generate an alternating magnetic field. Further, the induction cable 27 to be laid may be a single wire (single wire), or may be a so-called stereo type in which it is laid in parallel with proper separation on the left and right. The shape of the guide cable 27 may be a wire shape having a normal circular cross section or a flat strip shape.

FIG. 5 is a block diagram of the steering control device 32. The central processing unit 33 such as a microcomputer includes
A readable / writable memory (RAM) 34 and a read-only memory (ROM) 35 are connected. Further, the detection signals from the magnetic sensors 26a, 26b are converted into digital signals by the A / D converters 36, 36 and then input to the central processing unit 33, and the central lines of the work vehicle 1 with respect to the axis of the induction cable 27 are input. The central processing unit 33 calculates the lateral displacement deviation amount of the vehicle body and the lateral displacement direction of the vehicle body.

That is, the pair of magnetic sensors 26a, 26a
By calculating the detection signal of b, it is possible to obtain the deviation amount of the lateral deviation with respect to the guide cable 27 in the front part of the vehicle body and determine the direction of the lateral deviation (right or left).
A pair of left and right magnetic sensors are provided in front of and behind the work vehicle 1, and the front steering device is operated based on the detection and calculation results of the front pair of magnetic sensors, while the rear magnetic sensor is detected.
The rear steering device may be operated based on the calculation result.

Reference numeral 37 is an ultrasonic sensor for detecting an obstacle in the guide path, and the ultrasonic sensor 37 is
The wave transmitter 37a and the wave receiver 37b are connected to the step motor 3
It is configured to rotate horizontally at 8. In other words, the work vehicle 1 is configured to swing on both left and right sides in the traveling direction of the work vehicle 1 by a scanning region θo (−π / 2 ≦ θo ≦ π / 2 in the embodiment). Reference numeral 39 is an azimuth sensor such as a potentiometer for detecting the direction of the ultrasonic sensor 37 (in particular, the wave receiver 37b).

The duty ratio of the pulse of the ultrasonic wave transmitted by the wave transmitter 37a is τ / To. However, the duty of the ultrasonic pulse is τ (seconds), and the pulse repetition interval is T
o (seconds). Further, the maximum measurement distance capable of detecting an obstacle is Lo, the directivity angle of the wave receiver 37b of the ultrasonic sensor 37 is α, and the step motor 38 has a constant rotational scanning angular velocity ω (radian / second). Rotate with.

In this embodiment, the wave transmitter 3 that rotates.
The rotation scanning angular velocity ω is set so that the ultrasonic waves emitted from 7a are reflected by the obstacle at the maximum measurement distance Lo and can be received by the similarly rotating wave receiver 37b. Reference numeral 40 is a geomagnetic sensor for detecting the orientation of the work vehicle 1 by geomagnetism, reference numeral 41 is an electric resistance type level sensor for detecting the chemical liquid level (water level) in the chemical liquid tank 4, and reference numeral 42 is A flow rate detection sensor for detecting the amount of chemical liquid consumption during spraying is shown, and these are connected to an input terminal of an interface in the central processing unit 33.

The following are connected to the output terminals of the interface in the central processing unit 33. That is, the drive circuit 43 of the power pump 13 that sends the chemical liquid from the chemical liquid tank 4 to the spray nozzle 6, and the drive circuit of the control valve 44 that is provided in the middle of the chemical liquid flow pipe and that can regulate and block the flow amount of the liquid. 45, the electric drive circuit 46 of the electromagnetic solenoid 28R for right steering of the control valve 28 for automatic steering, the electric drive circuit 47 of the electromagnetic solenoid 28L for left steering, and the chemical liquid level in the chemical liquid tank 4 to the minimum. Then, the indicator lamp 48 that is turned on, the drive circuit 49 of the actuator that operates the traveling brake of the work vehicle 1, and the drive circuit 50 of the actuator that operates the clutch that disconnects the power transmission of the engine are connected.

If the drive circuit 45 of the dose adjusting valve 44 for adjusting the amount of the chemical liquid sprayed from the spraying section 5 can be remotely operated by a wireless operation device, the ON / OFF of the chemical liquid spraying can be executed. it can. Further, the detection signal of the vehicle speed sensor 52 is input to the central processing unit 33, and the traveling speed change mechanism 1
It is configured to output an output signal to a drive circuit 53 that operates an actuator such as a hydraulic cylinder 1 or a DC motor.

In FIGS. 8 and 9, reference numerals M1 to M1
M6 indicates the position of the standing tree, and the guide cable 27 is arranged between the standing tree rows of M1, M3, M5, ... On the right side and the standing tree rows of M2, M4, M6 on the left side substantially in parallel with the standing tree row. . In this configuration, the central processing unit 33 calculates the lateral shift amount for the guide cable 27 detected by the pair of left and right magnetic sensors 26a and 26b provided in the work vehicle 1, and detects the detected lateral shift amount and the steering angle sensor 25. A steering correction command amount signal for controlling the steering so that the lateral deviation amount becomes small is obtained from the value and the drive pulse signal is given to the electric drive circuits 46 and 47.

On the other hand, as shown in FIGS. 8 and 9, when the obstacle 55 is detected by the ultrasonic sensor 37 while the steering control is being executed so as to be substantially along the guide cable 27,
The central processing unit 33 performs control processing so that the steering for avoiding the obstacle location or the control for stopping the traveling is preferentially executed. The control of the obstacle detection will be described according to the subroutine flowchart shown in FIG. 6. Following the start, the distance to the object (obstacle 55) is detected while rotating the ultrasonic sensor at a predetermined scanning angular velocity. (Step 601). Then, a detailed description will be given later (FIG. 7).
(See the flowchart in FIG. 3) Obstacle determination control is executed (step 602), and when it is determined that there is an obstacle in step 603, obstacle avoidance control is executed to prevent the work vehicle 1 from colliding with the obstacle. Yes (Step 60)
4). This obstacle avoidance control is performed by stopping the traveling of the work vehicle 1,
Alternatively, in addition to stopping the traveling, an alarm sound is generated or an alarm display lamp (red lamp) 56 is blinked.
As described above, when the obstacle avoidance control is executed, it is more effective if the operator (monitor) at a remote position is notified by an alarm sound or lighting (blinking) of the alarm display lamp to that effect. Is. The alarm display lamp 56 may be mounted on a pillar 57 that projects upward from the work vehicle 1 so that it can be identified from a distance.

When it is judged in the step 604 that there is no obstacle, the detection value detected by the magnetic sensors 26a and 26b for the AC magnetic field generated from the normal induction cable 27 is read (step 605), and the induction is performed based on this detection value. The steering control that is substantially along the cable 27, that is, the so-called electromagnetic induction steering control is executed. Next, the obstacle determination control will be described. After the start, a counter value n for counting the number of detections of the ultrasonic sensor is set to 0 (step 701), and then the detection value L (n of the ultrasonic sensor is set. ) Is read (step 702). Next, at step 703, the detected value L (n) is set to the predetermined distance X (d).
Determine if it is less than. This predetermined distance X (d)
Is the maximum value of the distance required for avoidance measures such as stopping the vehicle body when the obstacle S exists, and is stored in advance in the read-only memory (ROM) 34 or the readable / writable memory (RAM) 35. deep. Also, the predetermined distance X
(D) is a value smaller than the maximum measurable distance Lo.

When it is judged no in step 703, the counter value n is incremented and it is judged whether or not the counter value exceeds a predetermined value N (steps 704, 70).
5) If the predetermined value N is not exceeded (yes), step 7
02, the ultrasonic wave detection value reading and discrimination are repeated a predetermined number of times N, and then “no obstacle”
(Step 706). By repeating the predetermined number of times in this manner, it is possible to prevent an erroneous determination that there is an obstacle even when there is an obstacle due to noise at the time of detection by the ultrasonic sensor. When it is determined to be yes in step 703, it is determined that “there is an obstacle”. Of.

Next, in the case where the guide path has a straight line portion and a rounding portion (curved portion), the steering control of the work vehicle 1 accurately and quickly along the respective portions will be described. In the above-mentioned case, the induction cable 2 is mounted on the work vehicle 1 with a pair of left and right magnetic sensors or two pairs of left and right magnetic sensors.
It is difficult to determine whether the location is a straight line section or a traveling section by simply detecting the deviation of the strength of the AC magnetic field generated from 7. Therefore, by calculating the moving average value of the results detected a plurality of times, the straight line portion and the traveling portion can be distinguished quickly, reliably and accurately. That is, Δ
Left and right paired magnetic sensors sampled every T hours
The lateral deviation amounts (Δe1, Δe2, Δe3, Δe4, Δe5, Δe6 ... Calculated from the detection results of 6a and 26b.
...) for each of the past several times (for example, five times),
When the average value is calculated, the moving average value Δem is obtained by the moving average method of arranging in time series. In the above case, the first moving average value Δem1 = (Δe1 + Δe2
+ Δe3 + Δe4 + Δe5) / 5, and the second moving average value Δem2 = (Δe2 + Δe3 + Δe4 + Δe5)
+ Δe6) / 5, the third moving average value Δem3 = (Δ
e3 + Δe4 + Δe5 + Δe6 + Δe7) / 5.
In the straight line portion, the guide cable 27 comes to be positioned at the left-right center of the work vehicle 1 due to the convergence due to the normal steering control.

On the other hand, it is general that the moving average value changes so as to increase at the traveling portion, particularly at the portion where the straight portion moves to the traveling portion. In addition, at the place where it moves from the traveling part to the straight part,
Generally, the moving average value changes so as to decrease. In the traveling section, the moving average value itself also shows a large value. Further, in the straight portion, the amount of lateral deviation E of the vehicle body with respect to the guide cable 27 is generally small, and the steering angle to be corrected is small. On the other hand, in the traveling section, the amount of lateral deviation of the work vehicle 1 with respect to the guide cable 27 is large, and the steering angle needs to be greatly changed.
Therefore, as shown in FIG. 10, for example, the zones are classified into five zones according to the magnitude of the lateral displacement amount of the vehicle body with respect to the guide cable 27 and the displacement direction. The first zone and the second zone mean that the work vehicle 1 is located on the left side with respect to the center of the left and right, the third zone means that the center position is located, and the fourth zone and the fifth zone are located on the right side position. . When the amount of lateral deviation, and by extension, the moving average value Δem of the calculation result is in the first zone and the second zone, it becomes a left turn turning portion, and the first zone is a turning portion having a small turning radius, and the second zone is It is judged to be a turning section with a large turning radius. Contrary to the above, the 4th zone and the 5th zone are the turning parts of the right turn, the 5th zone is the turning part of the small turning radius, and the 4th zone is the turning part of the large turning radius. It The third zone may be considered as a straight line portion.

The relationship between the lateral displacement amount E of the vehicle body and the moving average value in each zone is shown in "Table 1".

[0028]

[Table 1]

Then, a reference value KE is set in each zone, and a reference steering angle of the vehicle body is set for each reference value. For example, the intermediate value of the lateral deviation amount in each zone is set as the reference value KE. The deviation from the moving average value Δem calculated above with respect to this reference value KE is ρ, and the change rate of the deviation is Δρ,
The corrected steering command angle θ is preset with respect to the reference value KE. In this case, the correction steering command angle θ with respect to the straight line portion should be set relatively small, and the correction steering command angle θ with respect to the traveling portion should be set relatively large.

Then, the reference value KE in each zone
Of the steering correction command amount (angle) approximately proportional to the deviation ρ and / or the change rate Δρ of the deviation, and the drive pulse signal corresponding to the final steering correction command amount (angle) (θ + Δθ) Is given to the electric drive circuits 46 and 47, and steering control is performed so that the lateral shift amount with respect to the guide cable 27 in the traveling portion and the straight portion is reduced.

As described above, the manner in which the work vehicle 1 is steered along the straight line portion and the manner in which the work vehicle 1 is steered along the traveling portion are separately assumed in advance so that the steering correction command amounts are different. If it is set, an effect that accurate steering control can be quickly executed is achieved.

[0032]

According to the present invention, a magnetic sensor for detecting an alternating electric field from an induction cable and an ultrasonic sensor for detecting an obstacle on a guide path through which a work vehicle passes are provided in a work vehicle. If an ultrasonic sensor detects an obstacle, priority is given to steering control so as to follow the normal guidance cable, and control such as steering stop of the work vehicle is performed to avoid the obstacle. Since it is executed, it is safe to drive the work vehicle unmanned. When the obstacle avoidance control is executed, it is more effective to notify the worker (monitor) at a distant position by an alarm sound or lighting (blinking) of an alarm display lamp to that effect.

If an ultrasonic sensor for detecting an obstacle or the like is provided so as to reciprocate left and right, a wide range can be monitored with a small number of ultrasonic sensors, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side view of a drug spraying machine.

FIG. 2 is a plan view of the medicine spraying machine.

FIG. 3 is a schematic plan view of a steering device 14.

FIG. 4 is a control hydraulic circuit diagram of the steering device.

FIG. 5 is a functional block diagram of a steering control device.

FIG. 6 is a main flowchart.

FIG. 7 is a flowchart of an obstacle determination subroutine.

FIG. 8 is a plan view showing an outline of a guide route.

FIG. 9 is an explanatory diagram showing a mode of detection by an ultrasonic sensor.

FIG. 10 is an explanatory diagram of zones.

[Explanation of symbols]

 1 Work Vehicle 3 Handle 6 Spray Nozzle 7 Blower 8, 8 Front Wheel 9, 9 Rear Wheel 10 Engine 11 Travel Speed Change Mechanism 12 Power Transmission Mechanism 13 Power Pump 14 Steering Device 16 Hydraulic Circuit 17 Hydraulic Cylinder 22 Hydraulic Pump 23 Control Valve 25 Steering Angle Sensor 26a, 26b Magnetic sensor 27 Induction cable 28 Control valve for automatic steering 32 Steering control device 33 Central processing unit 37 Ultrasonic sensor 38 Step motor 46, 47 Drive circuit 55 Obstacle

Claims (1)

[Claims] 1. A work vehicle comprising a control means for detecting an AC electric field emitted from an induction cable with a magnetic sensor and steering the same so as to substantially follow the induction cable. An automatic steering control device for a work vehicle, comprising: an ultrasonic sensor for detecting; and means for executing obstacle avoidance control by detection of the ultrasonic sensor in preference to steering control along the guide cable.