System and method for automatic guidance control of a vehicle
View Patent ↗A system and method is provided for adaptive control of at least one parameter of an auto guidance control algorithm for a vehicle. The parameters may be varied according to a previously established look up table, or automatically adapted through the use of control logic, such as a “fuzzy logic” algorithm. The control parameters that can be adaptively controlled include steered wheel turn rate, proportional valve current gain, line acquisition rate and/or auto guidance control valve current limits. The control algorithm responds to the vehicle's operating parameters such as vehicle speed, tracking error, predicted heading, and hydraulic oil temperature to make adjustments to the auto guidance control parameters.
1. A method for automatically guiding a vehicle, the method comprising:
engaging an automatic guidance control system to steer a vehicle along a predetermined swath;
determining a swath path configuration of the predetermined swath to be subsequently travelled by the vehicle;
determining a cross track error for the vehicle relative to the predetermined swath;
determining a rate of change of the cross track error;
calculating a control parameter with the automatic guidance control system in response to the determined swath path configuration, the determined cross track error and the determined rate of change of the cross track error;
generating a control signal to steer the vehicle based on the calculated control parameter;
determining an operating condition for the vehicle;
calculating a response limit for the calculated control parameter in response to the determined operating condition;
adjusting the generated control signal by the calculated response limit;
applying the adjusted control signal to the vehicle to steer the vehicle along the predetermined swath;
wherein calculating a response limit comprises:
(a) identifying a membership function for at least one determined operating condition;
(b) calculating a degree of membership for the determined operating condition using the identified membership function; and
(c) applying a fuzzy logic algorithm to determine the response limit based on the calculated degree of membership.
2. The method of claim 1 wherein generating a control signal comprises generating a pulse width modulation control signal.
3. The method of claim 1 wherein the swath path configuration is one of a straight path, a curved path or a sharply curved path.
4. The method of claim 1 further comprising:
determining a vehicle travel speed;
determining a hydraulic oil temperature and engine speed;
determining a minimum turning radius associated with the vehicle; and
wherein calculating a control parameter comprises calculating a control parameter with the automatic guidance control system in response to the determined swath path configuration, the determined cross track error, the determined rate of change of the cross track error, the vehicle travel speed, the hydraulic oil temperature, the engine speed or the minimum turning radius associated with the vehicle.
5. The method of claim 1 wherein calculating a response limit comprises selecting a value of the response limit from a look up table based on the determined operating condition.
6. The method of claim 1 wherein the control parameter is one of steered wheel turn rate, proportional valve current gain, line acquisition rate, or auto guidance control valve current limit.
7. The method of claim 1 wherein the determined operating condition for the vehicle is one of vehicle travel speed, the cross track error, the rate of change of the cross track error, hydraulic oil temperature, engine speed, minimum turn radius for the vehicle or the swath path configuration.
8. The method of claim 7 wherein the determined operating condition for the vehicle further includes one of vehicle dynamics, side hill operation of the vehicle, implement side draft associated with the vehicle or change in vehicle mass.