Agricultural vehicle with satellite and variable wheel speed turn control

1. A steering system for a vehicle, the steering system comprising:

at least one first steerable wheel;

a first driver coupled to the at least one first steerable wheel and configured to drive the at least one first steerable wheel at variable rotation speeds;

at least one second steerable wheel opposite the at least one first steerable wheel;

a second driver coupled to the at least one second steerable wheel and configured to drive the at least one second steerable wheel at variable rotation speeds; and

a controller operably coupled to the first driver and the second driver and configured to:

enter a turn mode;

determine a first rotation speed of the at least one first steerable wheel and a second rotation speed of the at least one second steerable wheel to turn the vehicle and reach a defined second position from a first position, the second rotation speed being different than the first rotation speed;

output a first rotation speed signal to the first driver to rotate the at least one first steerable wheel at the first rotation speed and a second rotation speed signal to the second driver to rotate the at least one second steerable wheel at the second rotation speed in the turn mode; and

determine the vehicle has reached the defined second position based at least partially on the first rotation speed and the second rotation speed and responsively exit the turn mode.

2. The steering system of claim 1 , further comprising a global positioning satellite system (GPS) operably coupled to the controller and configured to output a position signal corresponding to a position of the vehicle, the controller being configured to determine the vehicle has reached a defined first position based on a received position signal to enter the turn mode.

3. The steering system of claim 2 , wherein the controller comprises a memory configured to store a map therein, the defined first position and the defined second position being defined in the map, the controller being configured to determine the first rotation speed and the second rotation speed based at least partially on a distance between the defined first position and the defined second position in the map.

4. The steering system of claim 3 , wherein a boundary region is defined in the map, the controller being configured to determine the first rotation speed and the second rotation speed so the vehicle turns entirely within the boundary region to reach the defined second position from the defined first position.

5. The steering system of claim 2 , wherein the controller is configured to not consider received position signals from the GPS system when determining the vehicle has reached the defined second position.

6. The steering system of claim 1 , further comprising a first wheel movement sensor associated with the at least one first steerable wheel and a second wheel movement sensor associated with the at least one second steerable wheel, the first wheel movement sensor being configured to output first wheel movement signals corresponding to a first wheel movement of the at least one first steerable wheel and the second wheel movement sensor being configured to output second wheel movement signals corresponding to a second wheel movement of the at least one second steerable wheel, the controller being operably coupled to the first wheel movement sensor and the second wheel movement sensor.

7. The steering system of claim 6 , wherein the controller is configured to determine the vehicle has reached the defined second position based on received first wheel movement signals and received second wheel movement signals.

8. The steering system of claim 6 , wherein the controller is further configured to at least one of:

determine the first wheel movement of the at least one first steerable wheel deviates from a defined first travel path to the defined second position from the first position and responsively output a first speed adjustment signal to the first driver to adjust the rotation speed of the at least one first steerable wheel; or

determine the second wheel movement of the at least one second steerable wheel deviates from a defined second travel path to the defined second position from the first position and responsively output a second speed adjustment signal to the second driver to adjust the rotation speed of the at least one second steerable wheel.

9. The steering system of claim 6 , wherein the controller is configured to determine a current heading of the vehicle based on a heading of the vehicle at the first position, received first wheel movement signals, and received second wheel movement signals.

10. An agricultural vehicle, comprising:

a chassis;

a header carried by the chassis and comprising a cutting mechanism; and

a steering system carried by the chassis, the steering system comprising:

at least one first steerable wheel;

a first driver coupled to the at least one first steerable wheel and configured to drive the at least one first steerable wheel at variable rotation speeds;

at least one second steerable wheel opposite the at least one first steerable wheel;

a second driver coupled to the at least one second steerable wheel and configured to drive the at least one second steerable wheel at variable rotation speeds; and

a controller operably coupled to the first driver and the second driver and configured to:

enter a turn mode;

determine a first rotation speed of the at least one first steerable wheel and a second rotation speed of the at least one second steerable wheel to turn the agricultural vehicle and reach a defined second position from a first position, the second rotation speed being different than the first rotation speed;

output a first rotation speed signal to the first driver to rotate the at least one first steerable wheel at the first rotation speed and a second rotation speed signal to the second driver to rotate the at least one second steerable wheel at the second rotation speed in the turn mode; and

determine the agricultural vehicle has reached the defined second position based at least partially on the first rotation speed and the second rotation speed and responsively exit the turn mode.

11. The agricultural vehicle of claim 10 , further comprising a global positioning satellite system (GPS) operably coupled to the controller and configured to output a position signal corresponding to a position of the vehicle, the controller being configured to determine the vehicle has reached a defined first position based on a received position signal to enter the turn mode.

12. The agricultural vehicle of claim 11 , wherein the controller comprises a memory configured to store a map therein, the defined first position and the defined second position being defined in the map, the controller being configured to determine the first rotation speed and the second rotation speed based at least partially on a distance between the defined first position and the defined second position in the map.

13. The agricultural vehicle of claim 12 , wherein a boundary region is defined in the map, the controller being configured to determine the first rotation speed and the second rotation speed so the agricultural vehicle turns entirely within the boundary region to reach the defined second position from the defined first position.

14. The agricultural vehicle of claim 13 , wherein the map is a field map and the boundary region is a headlands of the field map.

15. The agricultural vehicle of claim 11 , wherein the controller is configured to not consider received position signals from the GPS system when determining the vehicle has reached the defined second position.

16. The agricultural vehicle of claim 10 , further comprising a first wheel movement sensor associated with the at least one first steerable wheel and a second wheel movement sensor associated with the at least one second steerable wheel, the first wheel movement sensor being configured to output first wheel movement signals corresponding to a first wheel movement of the at least one first steerable wheel and the second wheel movement sensor being configured to output second wheel movement signals corresponding to a second wheel movement of the at least one second steerable wheel, the controller being operably coupled to the first wheel movement sensor and the second wheel movement sensor.

17. The agricultural vehicle of claim 16 , wherein the controller is configured to determine the agricultural vehicle has reached the defined second position based on received first wheel movement signals and received second wheel movement signals.

18. The agricultural vehicle of claim 16 , wherein the controller is further configured to at least one of:

determine the first wheel movement of the at least one first steerable wheel deviates from a defined first travel path to the defined second position from the first position and responsively output a first speed adjustment signal to the first driver to adjust the rotation speed of the at least one first steerable wheel; or

determine the second wheel movement of the at least one second steerable wheel deviates from a defined second travel path to the defined second position from the first position and responsively output a second speed adjustment signal to the second driver to adjust the rotation speed of the at least one second steerable wheel.

19. The agricultural vehicle of claim 16 , wherein the controller is configured to determine a current heading of the agricultural vehicle based on a heading of the agricultural vehicle at the first position, received first wheel movement signals, and received second wheel movement signals.

20. A method for steering a vehicle, the vehicle comprising at least one first steerable wheel, a first driver coupled to the at least one first steerable wheel, at least one second steerable wheel opposite the at least one first steerable wheel, a second driver coupled to the at least one second steerable wheel, and a controller coupled to the first driver and the second driver, the method being performed by the controller and comprising:

entering a turn mode;

determining a first rotation speed of the at least one first steerable wheel and a second rotation speed of the at least one second steerable wheel to turn the vehicle and reach a defined second position from a first position, the second rotation speed being different than the first rotation speed;

outputting a first rotation speed signal to the first driver to rotate the at least one first steerable wheel at the first rotation speed and a second rotation speed signal to the second driver to rotate the at least one second steerable wheel at the second rotation speed in the turn mode; and

determining the vehicle has reached the defined second position based at least partially on the first rotation speed and the second rotation speed and responsively exiting the turn mode.