JPH058608U - Automatic steering control device for traveling vehicle - Google Patents

Abstract

(57) [Summary] [Purpose] To allow an automatically traveling vehicle to be accurately steering-controlled along a guide cable at both a straight traveling portion and a traveling portion. According to the detected value of a steering angle sensor 25 in a steering device 14, it is determined whether the traveling vehicle 1 is located in a straight traveling portion or a traveling portion. When it is a straight traveling portion, a pair of left and right front magnetic sensors 26a, 26 provided on the traveling vehicle 1 with an AC electric field emitted from the induction cable 27.
Then, the steering control is performed so as to be substantially along the guide cable 27 based on the detection. When it is determined to be a traveling section, a pair of left and right rear magnetic sensors 60a provided on the traveling vehicle 1,
The steering control is carried out so that it is detected along with the guide cable 27 based on the detection by 60b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for automatically steering a traveling vehicle such as an agricultural work machine so as to substantially follow a guide cable laid along a guide path.

[0002]

[Prior Art]

 Conventionally, in traveling vehicles such as automatic traveling type chemical sprayers (speed sprayers) in orchards, etc., the amount of lateral deviation of the traveling vehicle from the guide cable buried in the ground along the work route (guide route) is large. The difference between the output values (voltage values) of the pair of left and right magnetic sensors, which are generated in correspondence with the horizontal deviation, is taken to determine the magnitude of the lateral deviation (deviation amount) and the direction of lateral deviation (determination of right or left). Based on these detection results, steering control is performed by changing the direction of the steered wheels so that the traveling vehicle travels along the guidance cable (see Japanese Utility Model Laid-Open No. 2-84909).

[0003]

[Problems to be solved by the device]

 In this case, as shown in FIG. 9, the magnetic sensors La and Lb such as the pair of left and right pickup coils are arranged in front of the axle of the front wheels 101 of the traveling vehicle 100, and the guide cable K is bent in a plan view. If the steering control is performed along the so-called traveling section, the following inconvenience occurs. 10 (a) and 10 (b), an alternating current is passed through the induction cable K, and a change in the intensity of the alternating magnetic field generated from the induction cable K is detected by a pair of left and right magnetic sensors La mounted on the front part of the traveling vehicle 100. It is a diagram schematically showing the case of sensing with Lb. Corresponding to the strength of the alternating magnetic field, the absolute value of the voltage | e1 | generated by the coil type magnetic sensor La on the left and the absolute value | e2 | of the voltage generated by the coil type magnetic sensor Lb on the right Taking the difference e (e = | e1 |-| e2 |) on the vertical axis, the lateral distance from the midpoint between the pair of left and right magnetic sensors La and Lb to the induction cable K, that is, the lateral displacement amount m. The horizontal axis is the horizontal axis, and the relationship between the lateral deviation amount m and the differential voltage value e is shown in FIG. As can be understood from this figure, on the left and right amount sides of the points P1 and P2 where the differential voltage value e shows a peak (maximum value, minimum value), the same differential voltage value e is obtained even if the lateral shift amount m is different. Therefore, when the traveling vehicle 100 is traveling in the traveling section, the guidance cable K is positioned below one of the magnetic sensors, and when the so-called lateral deviation amount m is large, the lateral deviation amount is away from the midpoint. It is difficult to determine whether the vehicle is on the near side or on the near side, and there is a large error in determining the steering angle to be corrected in this rounding section, so it is easy to meander or deviate from the guide cable K, and in a severe case. Had a problem that steering control was disabled.

In view of such conventional problems, an object of the present invention is to provide a steering control device capable of performing steering control with improved accuracy, regardless of a straight line portion and a traveling portion. ..

[0005]

[Means for Solving the Problems]

 In order to achieve this object, in the present invention, the AC electric field emitted from the induction cable is detected by the magnetic sensor mounted on the traveling vehicle, while the steering angle in the steering device is detected by the steering detection sensor, In a traveling vehicle provided with a control means for steering along substantially the same direction, a pair of left and right front magnetic sensors are provided in front of the front axle of the traveling vehicle, and a pair of left and right rear magnetic sensors are provided between the front and rear axles of the traveling vehicle. When the steering angle is within a predetermined small range, the steering control is executed based on the detection output of the front magnetic sensor, and when outside the steering angle range, the detection output of the rear magnetic sensor is used as the reference. The control means is provided so as to execute the steering control.

[0006]

【Example】

 Next, an embodiment in which the present invention is applied to a system for guiding an automatic traveling type drug 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 liquid tank 4 having a substantially L-shape in plan view and a spraying section 5 at the rear thereof. I have it.

The spray unit 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 the radial outward direction, and a blower 7 for sending air outward in the radial direction. The spray nozzles 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, and reference numerals 9 and 9 are left and right rear wheels. These four wheels are so-called four-wheel drive in which power from the engine 10 is transmitted through the traveling speed change mechanism 11 to be driven. It is a mold and rotates the blower 7 through the power transmission mechanism 12 of the power from the engine 10 and drives the power pump 13 for the spray nozzle 6.

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, and the power steering mechanism 15 includes a double-acting hydraulic cylinder 17 in a hydraulic circuit 16. When the hydraulic cylinder 17 extends, the rear wheels 9, 9 are changed to the left via the bell crank 18 having a W-shape in plan view, and the connecting rod 19 and the bell crank having a V-shape in plan view are changed. The front wheels 8 and 8 are changed to the right via 20 (the front wheels are changed to the left and the rear wheels are changed to the right when hydraulic cylinder 17 is contracted). It is a so-called four-wheel steering type that can be turned to the right.

The hydraulic circuit 16 is shown in FIG. 4, reference numeral 28 is an electromagnetic solenoid type control valve for the hydraulic cylinder 17 for automatic steering, and reference numeral 29 is for controlling the hydraulic cylinder 30 for running brake and clutch operation. These control valves are connected to a hydraulic pipe 31 branched from the upstream side of the control valve 23 for manual steering when hydraulic oil is fed from the hydraulic pump 22.

At the time of 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 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 front magnetic sensors 26a and 26b are provided at the front (in front of the front axle of the front wheels 8 and 8), and the front wheels 8 and 8 and the rear wheels 9 and Rear magnetic sensors 60a and 60b are provided at positions midway between the front and the rear (see FIG. 3). These magnetic sensors 26a, 26b, 60a, 60b may be pick-up coils formed by winding a conductor into a coil, or may be Hall elements, Hall ICs, magnetoresistive elements, or magnetic transistors. The strength of an AC magnetic field generated around the induction cable 27 can be detected by an AC current of an appropriate frequency applied to the induction cable 27 by the current generator 53. The guide cable 27 is laid in a groove formed along the guide route, which is the working route of the orchard, or buried in the ground.

It is to be noted that a pulsed direct current may be passed through the induction cable 27, or a pulse signal may be placed on the direct current to generate an alternating magnetic field. Further, the guide cable 27 to be laid may be in the form of a wire having a normal circular cross section or a flat band. FIG. 5 is a block diagram of the steering control device 32. A central processing unit 33 such as a microcomputer has a memory (RAM) 34 capable of reading and writing various data and a read-only memory (for storing a control program, etc.). ROM) 35 is connected. In the central processing unit 33, the detection signals from the front magnetic sensors 26a and 26b or the detection signals from the rear magnetic sensors 60a and 60b are converted into digital signals by the A / D converters 36 and 36. 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 subtracting the detection signals of the pair of magnetic sensors 26a, 26b or 60a, 60b, the deviation amount of the lateral deviation with respect to the guide cable 27 in the front part of the vehicle body and the direction of the lateral deviation (right or left) can be obtained. ) Can be determined. Reference numeral 37 is a preliminary geomagnetic sensor for discriminating the traveling portion, reference numeral 40 is an electric resistance type level sensor for detecting the chemical liquid level (water level) in the chemical liquid tank 4, and reference numeral 41 is A flow rate detection sensor for detecting the amount of chemical solution consumed during spraying is shown, and these are 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 solution from the chemical solution tank 4 to the spray nozzle 6 and the control valve 44 that can be installed in the middle of the chemical solution flow pipe to control and shut off the flow rate of the solution. The circuit 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 Indicator lamp 48 which is lit when the engine reaches a minimum level, a drive circuit 49 of an actuator that activates the traveling brake of the traveling vehicle 1, and a drive circuit 50 of an actuator that activates a clutch that disconnects the power transmission of the engine. Connect.

If the drive circuit 45 of the dose adjusting valve 44 for adjusting the amount of the chemical liquid sprayed from the spray section 5 is configured to be remotely controllable by a wireless operation device, the ON / OFF of the chemical liquid spraying is also executed. it can. Further, the detection signal of the vehicle speed sensor 52 is input to the central processing unit 33, and an output signal is output to a drive circuit 53 for operating an actuator such as a hydraulic cylinder of the traveling transmission mechanism 11 or a DC motor.

In this configuration, the central processing unit 33 calculates the lateral shift amount with respect to the guide cable 27 detected by the pair of left and right front magnetic sensors 26a, 26b or the rear magnetic sensors 60a, 60b provided in the traveling vehicle 1. Then, from the detected lateral deviation amount and the detection value of the steering angle sensor 25, a steering correction command amount signal for controlling the steering so that the lateral deviation amount becomes smaller is obtained, and the electric drive circuits 46 and 47 are provided. Drive pulse signal is given.

In this case, the output value of the steering angle sensor 25 is read out, and it is discriminated from the magnitude of the steering angle sensor 25 whether it is a traveling portion or a straight traveling portion. When it is determined that it is a straight portion, the front magnetic sensors 26a, 26b detect it. The lateral deviation amount with respect to the guide cable 27 is calculated based on the value (output value), and when it is determined to be the traveling section, the lateral deviation amount with respect to the induction cable 27 is calculated based on the detection values (output values) of the rear magnetic sensors 60a and 60b. The steering control is performed by calculating the corrected steering command angle for the straight part and the coast for selling the corrected steering command angle θ for the traveling part.

This control will be described in accordance with the subroutine flowchart shown in FIG. 7. Following the start, in step 701, the detected value of the steering angle sensor 25 is read, and then in step 702, the location where the traveling vehicle 1 is currently traveling is determined. When it is determined whether the vehicle is in the straight traveling zone or not, and when it is determined that the vehicle is in the straight traveling zone (yes), the detected values of the front magnetic sensors 26a and 26b are input (step 703), and the detected value is used as a reference. Then, the corrected steering command amount (angle) θ is calculated, and steering control is executed (steps 704 and 705). When it is determined in step 702 that the vehicle is not in the straight traveling zone (no), the detected values of the rear magnetic sensors 60a and 60b are input (step 706), and the corrected steering command amount θ is calculated based on the detected value. Then, steering control is executed (steps 704 and 705).

When the vehicle is not in the straight traveling zone, in other words, in the traveling portion, as shown in FIG. 6, the guide cable 27 curved in plan view is provided with a pair of left and right rear portions arranged in the front-rear midway portion of the traveling vehicle 1. When the magnetic sensors 60a and 60b are located between the left and right sides, as described above, the difference between the output values of the left and right magnetic sensors, that is, the error of the lateral shift amount with respect to the difference voltage value e decreases. Therefore, the traveling steering control along which the traveling vehicle 1 follows the traveling portion is accurately executed.

When determining whether or not the vehicle is in the straight traveling zone from the detected value E of the steering angle sensor 25, as shown in FIG. 8, the range from + E1 to −E1 is sandwiched between the detected value E = 0. The straight traveling zone, the range from + E1 to + E2 on the right side thereof is set to the right-turning zone for turning right, and the range from −E1 to −E2 is set to the left-turning zone for turning left. The value corresponding to is stored in the readable / writable memory (RAM) 34 in advance.

Further, in the straight line portion, the lateral displacement amount 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 traveling vehicle 1 with respect to the guide cable 27 is large, and the steering angle needs to be greatly changed. The zone of the traveling section may be divided into a small turning radius zone and a large turning radius zone.

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, an intermediate value of the lateral deviation amount in each zone is set as the reference value KE. A deviation from the calculated moving average value Δem with respect to the reference value KE is ρ, a rate of change of the deviation is Δρ, and a 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 increment Δθ of the correction steering command amount (angle) that is approximately proportional to the deviation ρ and / or the change rate Δρ of the deviation with respect to the reference value KE in each zone is calculated, and the final correction steering command is obtained. A drive pulse signal corresponding to the amount (angle) (θ + Δθ) is given to the electric drive circuits 46 and 47, and steering control is performed so that the amount of lateral deviation of the guide cable 27 at the traveling portion or the straight portion is reduced. ..

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

[0025]

[Operation and effect of the device]

 In the present invention, a pair of left and right front magnetic sensors are provided in front of the axles of the front wheels of the traveling vehicle to detect the AC electric field generated from the induction cable, and a pair of left and right rear magnetic sensors are provided between the front and rear axles of the traveling vehicle. Is provided. Then, the steering angle in the steering system of the traveling vehicle is determined based on the detected value of the steering angle sensor to determine whether the traveling vehicle is currently located in the traveling section or the straight traveling section. By controlling the steering based on the detection values of the pair of left and right front magnetic sensors, the steering along the straight ahead can be performed quickly and accurately. Then, when it is determined to be the traveling section, the steering control is executed based on the detection values of the pair of left and right rear magnetic sensors.

In the traveling section, an induction cable is often not positioned between the pair of left and right front magnetic sensors, and the error in the detection value by this magnetic sensor increases, while the guidance cable is introduced between the left and right rear magnetic sensors. This is because the state where the cable is located is considered to be a state in which there is little error in steering control along the traveling section. In this way, by changing the position of the magnetic sensor used as a criterion for the traveling section and the straight traveling section, it is possible to perform accurate steering control regardless of the traveling section and the straight traveling section. Is played.

[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 plan view showing a relationship between a guide cable and a traveling vehicle in a traveling section.

FIG. 7 is a subroutine flowchart.

FIG. 8 is an explanatory diagram of zones.

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

10A is an explanatory diagram showing a positional relationship between an induction cable and a pair of left and right magnetic sensors, and FIG. 10B is a diagram showing a relationship between output values (subtracted values) of a pair of left and right magnetic sensors and lateral shift amounts. Is.

[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 Sensors 26a, 26b Front magnetic sensor 60a, 60b Rear magnetic sensor 27 Induction cable 28 Control valve for automatic steering 32 Steering control device 33 Central processing unit 38 Step motor 46, 47 Drive circuit

Claims (1)

[Claims for utility model registration] [Claim 1] While the AC electric field generated from the induction cable is detected by a magnetic sensor mounted on a traveling vehicle, the steering angle in the steering device is detected by a steering detection sensor, and the induction cable is detected. In a traveling vehicle provided with control means for steering so as to substantially follow, a pair of left and right front magnetic sensors are provided in front of the front axle of the traveling vehicle, and a pair of left and right rear magnetic sensors are provided between the front and rear axles of the traveling vehicle. When the steering angle is within a predetermined small range, steering control is executed based on the detection output of the front magnetic sensor, and when outside the steering angle range, steering is performed based on the detection output of the rear magnetic sensor. An automatic steering control device for a traveling vehicle, characterized in that control means for executing control is provided.