Agricultural autopilot steering compensation

• US 20140074340A1
• Filed: 09/10/2012
• Published: 03/13/2014
• Est. Priority Date: 09/10/2012
• Status: Active Grant

• Current Assignee: Trimble Inc.
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Peake, John W., Pleines, Stephan, Wilson, Eric Karl
• Granted Patent: US 9,778,659 B2
• Time in Patent Office: Days
• US Class Current: 701/25
• CPC Class Codes: A01B 69/008 automatic
• CPC Class Codes: G05D 1/0278 using satellite positioning signals, e.g. GPS

Abstract

Agricultural autopilot steering compensation provides improved steering control when steerable wheels lose traction and/or in tight turns.

Claims

1. An agricultural autopilot comprising:

position, velocity and heading sensors;

steering actuators and drive wheel torque actuators; and

,

a microprocessor and memory that;

i. estimate a vehicle'"'"'s state using data provided by the sensors and a digital filter, and,

ii. use the actuators to guide the vehicle toward a pre-programmed path stored in the memory.

2. The autopilot of claim 1 wherein the drive wheel torque actuators include individual drive wheel brakes.

3. The autopilot of claim 1 wherein the drive wheel torque actuators include individual drive wheel electric motors.

4. The autopilot of claim 1 wherein the drive wheel torque actuators include individual drive wheel hydraulic motors.

5. The autopilot of claim 1 wherein the position and velocity sensors include a global navigational satellite system receiver.

6. The autopilot of claim 1 wherein the microprocessor implements a P-I-D feedback loop that controls the drive wheel torque actuators.

7. A method for guiding a vehicle along a path comprising:

providing an autopilot system including;

position, velocity and heading sensors; and

,

steering actuators and drive wheel torque actuators;

estimating a state of the vehicle by digitally filtering data provided by the sensors; and

,

reducing heading and cross-track errors between the state of the vehicle and a pre-programmed path by operating the steering actuators and the drive wheel torque actuators in response to a function of the errors.

8. The method of claim 7 wherein the function of the errors is proportional to the magnitude of the errors.

9. The method of claim 7 wherein the function of the errors is the time integral of the errors.

10. The method of claim 7 wherein the function of the errors is the time derivative of the errors.

11. The method of claim 7 wherein the function of the errors includes a threshold error value.

12. An agricultural autopilot comprising:

a steering wheel sensor;

steering actuators and drive wheel torque actuators; and

,

a microprocessor and memory that;

i. estimate a desired steering angle using data provided by the sensor and a digital filter,

ii. use the actuators to achieve an effective steering angle equal to the desired steering angle when the desired steering angle is less than or equal to an actual steering angle limit, and,

iii. use the actuators to achieve an effective steering angle greater than the actual steering angle when the desired steering angle is greater than the actual steering angle limit.

13. The autopilot of claim 12 wherein the drive wheel torque actuators include individual drive wheel brakes.

14. The autopilot of claim 12 wherein the drive wheel torque actuators include individual drive wheel electric motors.

15. The autopilot of claim 12 wherein the drive wheel torque actuators include individual drive wheel hydraulic motors.

16. A method for assisting an agricultural vehicle operator comprising:

providing an autopilot system including;

a steering wheel sensor; and

,

steering actuators and drive wheel torque actuators;

estimating a desired steering angle using data provided by the sensor and a digital filter;

using the actuators to achieve an effective steering angle equal to the desired steering angle when the desired steering angle is less than or equal to an actual steering angle limit; and

,

using the actuators to achieve an effective steering angle greater than the actual steering angle when the desired steering angle is greater than the actual steering angle limit.