JPH06161552A - Automatic steering controller for traveling vehicle - Google Patents

Abstract

PURPOSE:To exactly detect the lateral shifting amount of a detector to a guide cable regardless of variance in the height of the detector to the guide cable. CONSTITUTION:A preprocessing part 37 is provided with amplifiers 38 for amplifying detecting signals from detectors 26a and 26b, rectification/integration circuits 39 for smoothing, rectifying the signals amplified to a prescribed level and converting the result to digital signals, and differential arithmetic circuit 40 for calculating a differential output value between both of detectors. This device is composed of an average value arithmetic circuit 55 for calculating an average value (Vm=(Va+Vb)/2) of detecting signals from both of left and right detectors 26a and 26b, power arithmetic circuit 56 for calculating the cube value from the average value Vm, function arithmetic circuit 57 such as a ratio calculation circuit for calculating a ratio between the differential output value an the cube value of the average value Vm, and amplifier circuit 58 or the like. The value of the ratio is inputted from an output terminal 59 to a central processing unit and calculated, and the lateral shifting amount is calculated.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, an automatic traveling type chemical sprayer (speed sprayer) in an orchard or the like.
In the traveling vehicle 1 such as the above, an alternating current is caused to flow through the induction cable 27 buried in the ground along the work route (induction route), and a change in the intensity of the alternating magnetic field generated from the induction cable 27 is applied to the front of the traveling vehicle 1. Detected by a pair of left and right detector coils 26a and 26b attached to the
A pair of left and right detectors 26a, 26 generated corresponding to the magnitude of the lateral displacement of the traveling vehicle 1 with respect to the guide cable 27.
The difference between the output values (voltage values) Va and Vb at b is calculated to determine the magnitude of lateral deviation (deviation amount) and the direction of lateral deviation (determination of right or left), and the traveling vehicle is detected from these detection results. The steering control is performed by changing the direction of the steered wheels in the traveling vehicle so that the vehicle travels along the guide cable (JP-A-63-28830 and JP-A-63-204).
No. 415, Japanese Utility Model Laid-Open No. 2-84909, etc.).

In FIG. 7, the horizontal distances from the induction cable 27 to the vertical lines from the induction cable 27 to the detectors 26a and 26b are La and Lb, respectively, and the vertical distances from the induction cable 27 to the detectors 26a and 26b (the height direction). ), The induction cable 27 is connected to the pair of left and right detectors 26a,
If the amount of lateral deviation from the midpoint of the horizontal distance of 26b is x,
The steering control is performed so that the differential output Vref (= | Va−Vb |) becomes zero. In other words, steering control is performed so that La = Lb.

[0004]

By the way, the above-mentioned prior art JP-A-63-28830 and JP-A-63-830.
As described in Japanese Patent No. 204415, as shown in FIG.
Output value (output characteristic) V at each of the detectors 26a and 26b
a and Vb change so as to draw an upward convex curved line.

Then, the output values (output characteristics) Va,
Vb and the differential output Vref (= | Va−Vb |) change depending on the magnitude of the lateral displacement amount x of the detectors 26a and 26b with respect to the induction cable 27, and also change depending on the magnitude of the distance H in the height direction. To do. For example, when the distance H is small, the curve C1 in which the output value (detection value) is relatively large
Therefore, the differential output (difference in output value) Vref1 of the pair of left and right detectors 26a and 26b in the curve C1 having a large output characteristic is
(= | Va−Vb |) is large. Curves C2 and C3 in which the output value (detection value) becomes relatively smaller as the distance H becomes larger are shown. For example, the differential output (difference in output value) Vref2 (= difference in output value) in the curve C2 having small output characteristics is shown. ｜ Va−
Vb |) also becomes smaller.

In other words, the differential output when the lateral deviation amount x is large when the distance H in the height direction is small,
The differential output when the lateral shift amount x is small when the distance H is large can be about the same. Therefore, even if the road surface of the guide route on which the guide cable is laid is flat, an error may occur in the height position where the detector is mounted on the traveling vehicle, the mounting height may be changed, etc. In addition, when the relative height position between the induction cable and the detector fluctuates, there is an inconvenience that the lateral deviation amount cannot be accurately known only by the value of the differential output.

According to the invention disclosed in Japanese Patent Laid-Open No. 63-288307, the inconvenience is solved by providing an arithmetic circuit for executing the arithmetic operation of the correction amount. The present invention is an improvement thereof, and from the result of experiments, the present inventor determined from the ratio of the value of the differential output of the pair of left and right detectors and the function of the value of the sum of the outputs of the pair of left and right detectors. It is an object of the present invention to provide a steering control device capable of accurately and promptly executing steering control based on the result of confirmation that the following function is substantially constant.

[0008]

In order to achieve this object, in the present invention, an AC electric field generated from an induction cable is detected by a pair of left and right detectors mounted on a traveling vehicle, and substantially follows the induction cable. In a traveling vehicle provided with control means for steering in such a manner, a differential operation circuit for calculating the value of the differential output of the pair of left and right detectors, and the value of the differential output of the pair of left and right detectors , A function arithmetic circuit for operating a function consisting of a ratio of the sum of the outputs of the pair of left and right detectors and a function, and the lateral displacement of the pair of left and right detectors with respect to the induction cable from the output values of the both arithmetic circuits. The control means for calculating the quantity is provided.

[0009]

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. The speed sprayer has a driving operation section 2 provided with a handle 3 on the front side of a traveling vehicle 1, and the traveling vehicle 1 is provided with a chemical liquid tank 4 having a substantially L shape in a plan view and a spraying section 5 at a rear portion thereof. ing.

The spraying section 5 is provided with a large number of spray nozzles 6 facing the outer peripheral surface of the traveling vehicle 1 excluding the lower surface of the traveling vehicle 1 at appropriate intervals in a radially outward direction, and a blower 7 for sending air in the radially outward direction,
The spray nozzle 6 can be spray-controlled so as to perform spraying work in each of the three sections on the left and right and the upper surface of the traveling vehicle 1 or the two sections on the left and right. 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. To change the front wheels 8 and 8 to the right (when the hydraulic cylinder 17 is contracted, the front wheels 8 are changed to the left and the rear wheels 9 are changed to the right). It is a so-called four-wheel steering type that can be changed.

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 branched from upstream of the control valve 23 for manual steering.

During manual steering, the hydraulic motor 21 that sends an 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 traveling vehicle 1, a pair of left and right detectors 26a,
26b is provided. The detectors 26a and 26b may be pickup coils formed by winding a conductor in a coil shape, or may be Hall elements, Hall ICs, magnetoresistive elements, or magnetic transistors, and may be induction cables in an AC current generator. By an alternating current of appropriate frequency applied to 27,
The strength of the AC magnetic field generated around the induction cable 27 can be detected. Induction cable 27
Will be laid in the trench formed along the guide route, which is the working route of the orchard, or will be buried underground. Further, the guide cable 27 may be laid in an overhead line as an aerial cable above the traveling vehicle (at a higher position).

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 guide cable 27 to be laid may be in the form of an ordinary wire having a circular cross section or a flat band. FIG. 6 is a block diagram of the steering control device 32. The central processing unit 33 such as a microcomputer has a readable / writable memory (RA
M) 34 and a read-only memory (ROM) 35 in which a control program and the like are stored are connected.

Further, as shown in FIG. 5, the central processing unit 33 is inputted through a pre-processing unit 37 which processes the detection signals from the detectors 26a and 26b. The pre-processing unit 37 is for calculating an equation of a predetermined ratio obtained according to the principle described later, and the pre-processing unit 37 is an amplifier 3 for amplifying the detection signals from the detectors 26a and 26b.
8, 38, rectifying / integrating circuits 39, 39 for smoothing and rectifying a signal amplified to a predetermined level, and then converting it into a digital signal, and a difference for obtaining a difference (differential output value) between outputs of both detectors. Dynamic operation circuit 40, the left and right detectors 26a, 2
An average value calculation circuit 55 for obtaining the average value (Vm = (Va + Vb) / 2) of the detection signal from 6b, from the average value Vm to 3
A power calculation circuit 56 for calculating a power value, and a differential output value,
It is composed of a function calculation circuit 57 such as a ratio calculation circuit for calculating the ratio of the average value Vm to the cube value, an amplification circuit 58, and the like.

The value of the ratio is input to the central processing unit 33 from the output terminal 59 of the amplifier circuit 58, and the read-only memory (ROM) 35 or the readable / writable memory (R) is input.
The lateral deviation amount x is obtained based on a constant (a value in Table 1 described later) stored in the (AM) 34. (Principle) As described in FIG. 9, the midpoint of the horizontal straight line connecting the detectors 26a and 26ba at the left-right distance 2c is set to O, and the induction cable 27 extends from the point O in parallel with the perpendicular line orthogonal to the horizontal straight line. A vertical line is set up, the height distance y from the guide cable 27 to the horizontal straight line, the horizontal shift amount x from the guide cable 27 to the vertical line, the distance a from the guide cable 27 to one detector 26a, and the guide cable 27 to the other. If the distance b to the detector 26b of the above is set to (c−x) ² + y ² = a ² (c + x) ² + y ² = b ² from the Pythagorean theorem. When y is deleted from these two equations and x is expanded, equation 4cx = (b ² −a ² ) (1) is obtained.

On the other hand, since the detection outputs of the detectors 26a and 26ba are inversely proportional to the distances a and b, if the constants are α, Va = α / a and Vb = α / b, and the above (1)
When a and b in the equation are deleted, 4cx = α ² [(1 / Va) ² − (1 / Vb) ² ] ... (2). Since c and α are constants, K = α ² / 4c
Then, the formula (2) is expanded to obtain x = K (Va ² −Vb ² ) / (Va ² · Vb ² ) x = K [(Va−Vb) · (Va + Vb) / Va ² · Vb ² ] (3) When the equation (3) is modified, (Va−Vb) = xVa ² Vb ² / K (Va + Vb) (4)

By the way, the differential output value (Va-Vb) is
From the result of the experiment, it is known that the curve is as shown by the dotted line in FIG. Therefore, the left and right detectors 26a, 2
When the induction cable 27 is located between 6ba, that is,
When the lateral shift amount x is between x1 and x2, the differential output value (Va-
It is assumed that Vb) is approximated to a curve that approximates a cubic curve or a linear line with respect to the variable of the lateral shift amount x.

On the other hand, the sum (Va + Vb) of the detection outputs of the two detectors 26a and 26ba, or the average value Vm = (Va + Vb)
The function of / 2 has a substantially constant value in the section where the induction cable 27 is located between the left and right detectors 26a and 26ba, and the constant value changes according to the height distance y. Therefore, xVa ² Vb ² / (Va + V of the right side of the above equation (4)
Since b) is a linear function of x, by multiplying it by an appropriate constant coefficient β, in the section where the lateral deviation amount x is from x1 to x2, the differential output value (Va-Vb) and It may be considered that the linear function of x coincides or becomes parallel. Therefore, Va ² Vb ² / (Va + Vb) ≒ (Va + Vb)
^3/8 = (Vm) ³ assuming. That is, Va ² Vb ² / (Va
+ Vb) is assumed to be the cube of the average value of the outputs of the left and right detectors 26a and 26ba.

Then, the above equation (4) is transformed into (Va-Vb) / (Vm) ³ · x = 1 / K (5) In the experiments conducted by the present inventor, when the amount of lateral deviation is xcm and the height distance is ycm, the results shown in Table 1 below are obtained as the value of (1 / K) in the equation (5). That is, in the section where the lateral shift amount x is from x1 to x2, the ratio between the denominator and the numerator on the left side of the equation (5) is substantially constant (1 / K). In other words,
It can be seen that the differential output value (Va−Vb) and the function of xVa ² Vb ² / (Va + Vb) are parallel.

[0022]

[Table 1]

Therefore, as can be understood from this result, within the above range of x and y, the above equation (5) is modified so that x = [(Va-Vb) / (Vm) ³ ] /0.117 ( If the value of (Va-Vb) / (Vm) ³ is obtained from the equation (6), the lateral shift amount x can be obtained regardless of the value of the height distance y.

In the equation (5), assuming that the denominator on the left side is a cubic function of x, (Va-Vb) / (Vm) ³ · x ³ = 1 / K '... (7) Then, the lateral shift amount x can be obtained in the same manner as described above. In these cases, (1 / K) or (1 / K ')
Of the read-only memory (RO
M) or a readable / writable memory (RAM).

The differential operation circuit 40 for differential output, the function operation circuit 57 for the function of the sum or the average value, and the like may be constructed by an operation circuit with electronic elements dedicated to the function, but the operation unit of the microcomputer is used. It can be used and built as software. In this way, the central processing unit 33 calculates the amount of lateral deviation of the center line of the traveling vehicle 1 with respect to the axis of the guide cable 27 and whether the lateral deviation direction of the vehicle body is left or right.

That is, by calculating the detection signals of the pair of detectors 26a and 26b, it is possible to determine the lateral deviation amount of the vehicle body with respect to the guide cable 27 and to determine the lateral deviation direction (right or left). A pair of left and right detectors are provided in front of and behind the traveling vehicle 1, and the front steering device is operated based on the detection / calculation results of the front pair of detectors, while the rear steering is detected based on the detection / calculation results of the rear detector. The device may be configured to operate.

Further, a signal obtained by amplifying the function value of the sum of the outputs of both detectors such as the cubed value of the average value Vm through the amplifier circuit 60 is input from the output terminal 61 to the central processing unit 33. .. is compared with the constant threshold value Vs to determine whether the disconnection of the induction cable 27 or the left and right detectors 26a and 26b largely deviate from the location of the induction cable 27.

Because, in the output of either the left or right detector, as shown in FIG. 10, the output value when the induction cable 27 is at the midpoint of the pair of left and right detectors 26a and 26b and the induction cable 27 is Since the output is approximately the same as when the output deviates (laterally shifts) to the outside of the detector, it is possible to detect whether the induction cable is broken or the induction cable just by detecting the output of one detector. On the other hand, it is impossible to determine whether the pair of left and right detectors are largely laterally displaced (deviation). However, when the induction cable 27 is located between the pair of left and right detectors 26a and 26b, the sum of the outputs of both detectors or the value of the function of the sum becomes large, and when the induction cable 27 is disconnected or when the induction cable 27 is disconnected. When the cable 27 is largely deviated (laterally displaced) to the outside of the detector, the sum of the outputs of the two detectors or the value of the function of the sum is extremely small, so that it can be easily discriminated.

Further, the sum of the outputs of both detectors or the value of the function of the sum is used to calculate the amount of lateral deviation, to detect the disconnection of the induction cable and to detect that the induction cable 27 deviates largely outside the detector. When used at the same time, there are advantages that extra parts such as a disconnection detection sensor can be omitted, and the determination can be made extremely easily and accurately. Reference numeral 41 is the chemical liquid tank 4
A level sensor for detecting a chemical liquid level (water surface height) in the inside, a reference numeral 42 denotes a flow rate detecting sensor for detecting a chemical liquid consumption amount at the time of spraying, and these are A / D converters 3
After being converted into a digital signal at 6, it is connected to the input terminal of the 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 traveling vehicle 1, and the drive circuit 50 of the actuator that operates the clutch that interrupts 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 the 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 this structure, the central processing unit 33 uses the pair of left and right detectors 26a provided on the traveling vehicle 1,
26b, the lateral deviation amount for the guide cable 27 detected is calculated, and a steering correction command amount signal for steering control so as to reduce the lateral deviation amount is obtained from the detected lateral deviation amount and the detection value of the steering angle sensor 25. , A drive pulse signal is supplied to the electric drive circuits 46 and 47, and
The steering control, which is substantially in line with No. 7, so-called electromagnetic induction steering control is executed.

[0033]

According to the present invention, the control means for detecting the AC electric field from the induction cable by the pair of left and right detectors mounted on the traveling vehicle and steering the vehicle so as to substantially follow the induction cable is provided. In a traveling vehicle, a differential operation circuit for calculating the value of the differential output of the pair of left and right detectors, the value of the differential output of the pair of left and right detectors, and the output of the pair of left and right detectors And a function computing circuit for computing a function consisting of a ratio of the value of the sum of the two, and a control means for computing the lateral deviation amount of the pair of left and right detectors with respect to the induction cable from the output values of the both computing circuits. Therefore, even if the heights of the guide cable and the detector vary, the lateral shift amount of the detector with respect to the guide cable can be accurately detected, and the traveling vehicle can be steering-controlled along the guide cable.

Therefore, when the detector is mounted on the traveling vehicle, there is also an effect that problems relating to an error in the mounting height position of the detector and a change in the mounting position due to design specifications are eliminated.

[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 an arithmetic circuit for the output of the detector.

FIG. 6 is a functional block diagram of a control device.

FIG. 7 is a diagram showing a positional relationship between a detector and an induction cable when the traveling vehicle is viewed from the rear surface.

FIG. 8 is an explanatory diagram of output characteristics due to a difference in height of the detector with respect to the induction cable.

FIG. 9 is an explanatory diagram showing a positional relationship between a detector and an induction cable.

FIG. 10 is an explanatory diagram of an output by the detector.

[Explanation of symbols]

 1 Traveling 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 Detector 27 Induction cable 28 Control valve for automatic steering 32 Steering control device 33 Central processing unit 37 Pre-processing unit 38, 58, 60 Amplifier 40 Differential operation circuit 45, 46, 47 Drive circuit 55 Average value operation circuit 56 Magnitude calculation circuit 57 Function calculation circuit 59, 61 Output terminal

Claims (1)

[Claims] 1. A traveling vehicle comprising a control means for detecting an AC electric field generated from an induction cable by a pair of left and right detectors mounted on the traveling vehicle, and steering the vehicle substantially along the induction cable. A differential operation circuit for calculating the value of the differential output of the pair of left and right detectors, a function of the value of the differential output of the pair of left and right detectors, and the value of the sum of the outputs of the pair of left and right detectors And a function calculating circuit for calculating a function consisting of the ratio of the ratio of the two, and a control means for calculating the lateral deviation amount of the pair of left and right detectors with respect to the induction cable from the output values of the both calculating circuits. Automatic steering control device in a vehicle.