JPH07184411A - Steering of autonomously traveling farm vehicle - Google Patents

Abstract

PURPOSE:To provide a steering method for an autonomously traveling farm vehicle to detect the traveling direction by a traveling direction sensor, calculate the deviation from the target direction and control the steering mechanism of the autonomously traveling vehicle in such a manner as to drive the vehicle constantly toward the target direction. CONSTITUTION:This steering method comprises the detection of the traveling direction by a traveling direction sensor such as a geomagnetic direction sensor or a gyroscope, the calculation of the deviation from the target direction and the control of the steering mechanism of the autonomously traveling vehicle to drive the vehicle constantly toward the target direction. In the above process, a necessary steering operation is performed at an interval of the steering period based on the relationship between the steering extent of the steering mechanism and the change of the traveling direction of the vehicle, the steering mechanism is returned to the straightly moving state and the operations are repeated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering mechanism for an autonomous vehicle, in which the vehicle traveling direction sensor detects the traveling direction, the deviation value from the target direction is confirmed, and the vehicle always travels toward the target direction. The present invention relates to a method for steering an agricultural autonomous vehicle that controls a vehicle.

[0002]

2. Description of the Related Art Conventionally, a vehicle traveling direction sensor such as a geomagnetic direction sensor or a gyro is used to detect a traveling direction, and a deviation value from the target direction is confirmed, so that the vehicle always travels toward the target direction. A steering method for controlling a steering mechanism of a vehicle is known. An example thereof will be described with reference to FIG. 4. In a general Ackerman type steering mechanism, as a flow of the steering angle control, the steering angle changes from the output of the steering command value a to the end of steering even if the steering operation is performed. The actual traveling direction of the vehicle changes only after a certain time t (traveling a certain distance). That is, it is understood that, when a certain steering angle a is given, the vehicle has a property of changing its direction with time t.

[0003]

As described above, in the conventional steering method, the vehicle heading is detected by the vehicle heading sensor such as a geomagnetic heading sensor or a gyro, and the deviation value from the target heading is confirmed to check the vehicle. When given a certain steering angle a so that the vehicle always travels toward the target azimuth, the vehicle greatly changes its azimuth with time t, and thus it takes a long time to return the steering angle to zero. The present invention has been made for the purpose of solving the above problems.

[0004]

In order to achieve the above object, the present invention detects a traveling direction by a vehicle traveling direction sensor such as a geomagnetic direction sensor or a gyro and confirms a deviation value from a target direction to detect a vehicle. In a steering method for controlling a steering mechanism of an autonomous traveling vehicle so that the vehicle always travels toward a target azimuth, based on the relationship between the steering amount of the steering mechanism and the change amount of the vehicle traveling azimuth for each steering cycle of the steering mechanism. It is characterized in that the operation for returning the steering mechanism to the straight-ahead state is performed again after the necessary steering amount is given, and the steering is automatically performed.

[0005]

According to the above-mentioned means, the steering method for the agricultural autonomous vehicle of the present invention provides the necessary steering amount based on the relationship between the steering amount of the steering mechanism and the change amount of the vehicle traveling direction for each steering cycle of the steering mechanism. After turning the steering mechanism, the steering mechanism is returned to the straight-ahead state and the automatic steering operation is performed again. Therefore, the steering angle is returned to zero for each cycle of the steering operation, and the next steering operation is always started from the straight-ahead state. .

[0006]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The agricultural autonomous traveling vehicle steering method according to the present invention detects a traveling direction by a vehicle traveling direction sensor such as a conventionally known geomagnetic direction sensor (TMS) or a gyro and confirms a deviation value from a target direction to always aim at the vehicle. This is an improvement on the premise of the steering method for controlling the steering mechanism of the autonomous vehicle so that the vehicle travels in the azimuth direction, and well-known parts are omitted in the drawing.

A method for steering an agricultural autonomous vehicle according to the present invention will be described with reference to the flowcharts of FIGS. 1 and 2. When an agricultural tractor that is an autonomous vehicle starts (starts) 1 in a field, initialization 2 of the system is first performed. Next, the selection 3 of the target azimuth in the first stroke is performed, and the traveling / work start 4 is performed. TMS (geomagnetic direction sensor) data collection 5 is performed after running / starting work 4. Then, the steering 6 is performed based on the vehicle azimuth information based on the TMS data. With this steering, the travel time has passed 7
Later, if YES here, it will come to running / work stop 8,
If NO, the process returns to TMS data collection 5.

From the running / work stop 8 to the end 9 of the stroke,
In the case of YES here, the end (end) 10 is set. In the case of NO at the end of stroke 9, if the target direction for the next stroke is selected 1
1 is performed, turning (one-side brake / steering angle ≧ 50 °) 12 is performed, TMS data collection 13 is further performed, and vehicle direction ≧
The target azimuth 14 is set, and if YES here, the turning stop 15 is performed and the process returns to the running / work start 4. When the vehicle direction ≧ target direction 14 is NO, the vehicle turns (one brake / steering angle ≧
50 °) Return to 12.

In the present invention, as shown in FIGS. 2 and 3, in the steering 6 based on the vehicle azimuth information in the flowchart of FIG. 1, the deviation 16 from the target azimuth is calculated 16 to calculate the steering command value a. 17 is performed, and the command value a is output 18 to the steering mechanism. Then, after waiting for t seconds, 19 outputs the command value zero to the steering mechanism, waits for 21 seconds again, and the steering ends 22.

The steering command value a is calculated by the following equation. φ = Vt / L × a (deviation from the target azimuth) However, angle unit; ° t = 0.6s (a ≦ 9 °) = {0.6+ (a-9) × 0.03} s (a> 9 °) V: Vehicle traveling speed (m / s) L: Vehicle axle distance

Then, as shown in FIG. 3, the flow of the steering angle control outputs the command value a to the steering mechanism 18-t seconds waiting time 19
-Output a command value of zero to the steering mechanism. Wait for 20-t seconds. 21
-While proceeding to the end of steering 22, the change in the steering angle returns from 0 (straight ahead state) to 0 (straight ahead state) after a lapse of time t, and the change in the vehicle direction changes by φ. Therefore, as is clear from comparison with the conventional steering method shown in FIG. 4, the steering operation can be made gentle and stable, and the steering speed can be reduced when the traveling speed is slow as in an agricultural vehicle. The traveling direction can be easily converged to the target direction even if (the speed at which the steering wheel is turned) is relatively slow or the steering cycle is considerably long (several seconds). As a result, the control of the vehicle is facilitated, and it is possible to reduce the possibility that the field scene is roughened by the quick steering.

[0012]

As described above, according to the method for steering an agricultural autonomous vehicle of the present invention, based on the relationship between the steering amount of the steering mechanism and the change amount of the vehicle traveling direction for each steering cycle of the steering mechanism, Since the operation for returning the steering mechanism to the straight traveling state is performed again after the necessary steering amount is given, the automatic steering is performed, and therefore the following effects can be obtained.

The steering operation can be made gentle and stable. When traveling speed is slow like an agricultural vehicle, the traveling direction can be easily changed to the target direction even if the steering speed (almost the speed at which the steering wheel is turned) is relatively slow or the steering cycle is considerably long (several seconds). Can converge. Therefore, the control of the vehicle is facilitated, and it is less likely that the field scene will be roughened by quick steering.

[Brief description of drawings]

FIG. 1 is a flow chart showing the “overall flow of autonomous traveling software by a vehicle traveling direction sensor” according to the present invention.

FIG. 2 is a detailed flowchart of a “steering based on vehicle direction information” portion in FIG. 1.

FIG. 3 is a diagram showing a flow of steering angle control of the steering method according to the present invention, a change in steering angle, a change in vehicle azimuth, and an equation for obtaining a steering command value.

FIG. 4 is a diagram showing a flow of a steering angle control of a conventional steering method, a change in a steering angle, and a change in a vehicle azimuth.

[Explanation of symbols]

 1 Start (Start) 2 System initialization 3 Selection of target direction for the first stroke 4 Start of running / working 5 Collection of TMS (geomagnetic direction sensor) data 6 Steering based on vehicle direction information 7 Traveling time 8 Stop running / working 9 End of stroke 10 End (end) 11 Selection of target azimuth for the next stroke 12 Turning (single brake / steering angle ≧ 50 °) 13 TMS data collection 14 Vehicle azimuth ≧ target azimuth 15 Turning stop 16 Calculation of deviation from target azimuth 17 Steering Calculation of command value a 18 Output of command value a to steering mechanism 19 Wait for t seconds 20 Output zero command value to steering mechanism 21 Wait for t seconds 22 End of steering

Claims (1)

[Claims] 1. Steering of an autonomous vehicle so that the vehicle always travels toward the target azimuth by detecting the traveling azimuth by a vehicle traveling azimuth sensor such as a geomagnetic azimuth sensor or a gyro and confirming a deviation value from the target azimuth. In the steering method for controlling the mechanism, based on the relationship between the steering amount of the steering mechanism and the amount of change in the vehicle traveling direction for each steering cycle of the steering mechanism, after the necessary steering amount is given, the steering mechanism is made straight again. A steering method for an agricultural autonomous vehicle, characterized in that a returning operation is performed again to perform automatic steering.