Farm apparatus having implement sidehill drift compensation

• US 20080086249A1
• Filed: 10/05/2006
• Published: 04/10/2008
• Est. Priority Date: 10/05/2006
• Status: Active Grant

• Current Assignee: PTx Trimble LLC
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Lange, Arthur F.
• Granted Patent: US 7,844,378 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: A01B 15/20 Special adjusting means for tools of ploughs drawn by, or mounted on tractors working on hillsides or slopes
• CPC Class Codes: A01B 69/008 automatic
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• CPC Class Codes: G05D 1/0278 using satellite positioning signals, e.g. GPS

Abstract

An apparatus and method using GPS for dynamically adjusting side-to-side positioning of a farm implement along a geographical path. The apparatus includes a global positioning system (GPS) antenna disposed on the farm implement, a GPS receiver coupled to the GPS antenna for determining a location of the GPS antenna, and a dual guidance computer for comparing the location to stored geographical coordinates of a desired path for providing a guide signal for offsetting the lateral position of an adjustable hitch or angling a wheel or ground rudder in a steerable implement for guiding the implement along the path; and a range extent signal for maintaining the offset of the hitch or steering angle of the implement within its dynamic range.

Claims

1. An apparatus for steering a vehicle in order to guide a farm implement along a desired path, comprising:

a compensation computer having a first sidehill computer for computing a roll height compensation from a fixed function of a roll angle of said vehicle and a height of a global navigation satellite system (GNSS) antenna disposed on said vehicle; and

a second sidehill computer for computing a sidehill tracking compensation from a variable sidehill tracking function of said roll angle, said variable sidehill tracking function determined for compensating a sidehill tracking error at least partly due to implement sidehill drift; and

a sidehill compensator for determining a compensated crosstrack error based on said desired implement path, GNSS position measurements derived from GNSS signals received in said GNSS antenna, said roll height compensation and said tracking compensation;

said compensated crosstrack error for use for steering said vehicle in order to guide said implement to said desired path.

2. The apparatus of claim 1, wherein:

said height is the height of said GNSS antenna above ground.

3. The apparatus of claim 1, wherein:

said sidehill tracking function is constructed for providing values of said tracking compensation corresponding to values of said roll angle, respectively, for compensating said tracking error between an actual implement path and said desired vehicle path when said vehicle having said roll angle is steered for minimizing said compensated crosstrack error.

4. The apparatus of claim 1, wherein:

said sidehill tracking function is constructed for providing a best fit between several values of said tracking compensation computed from several values of said roll angle, respectively and values of said tracking error measured at said several values of said roll angle.

5. The apparatus of claim 1, wherein:

said steering device is constructed for providing a steering signal for steering said vehicle in order to minimize said compensated crosstrack error.

6. The apparatus of claim 1, further comprising:

a roll filter for providing a time constant to said tracking compensation for causing said compensated crosstrack error to have a slower response to changes in said roll angle than to changes in a crosstrack error between said desired implement path and a GNSS-measured path determined with said GNSS position measurements.

7. The apparatus of claim 1, further comprising:

a tracking learn computer for editing said sidehill tracking function according to a current said tracking error and a current said roll angle, said edited sidehill tracking function for computing said sidehill tracking compensation for compensating for said current tracking error for said current roll angle.

8. The apparatus of claim 7, further comprising:

a function edit entry device for issuing a function freeze signal to said tracking learn computer, said tracking learn computer constructed for determining said current tracking error at said function freeze signal.

9. The apparatus of claim 7, wherein:

said tracking learn computer includes a function coefficient calculator for editing said sidehill tracking function by re-calculating one or more coefficients of said function.

10. The apparatus of claim 7, wherein:

said drift learn computer includes a function order calculator for editing said sidehill tracking function by determining an order for said function.

11. The apparatus of claim 1, wherein:

a tracking learn computer for editing said sidehill tracking function for minimizing a current said compensated crosstrack error for a current path of said vehicle.

12. The apparatus of claim 1, wherein:

a tracking learn computer for editing said sidehill tracking function for a best fit of differences between several values of said sidehill tracking compensation for several values of said roll angle, respectively, and several values of said tracking error for said several values of said roll angle for providing a current said sidehill tracking compensation for said current roll angle.

13. The apparatus of claim 1, further comprising:

a nudge summer for adding a nudge difference to said compensated crosstrack error for providing a current said compensated crosstrack error; and

a tracking learn computer for measuring a current said tracking error using said nudge difference or said current compensated crosstrack error; and

using said current tracking error and a current said roll angle for editing said sidehill tracking function.

14. A method for steering a vehicle in order to guide a farm implement along a desired path, comprising:

computing a roll height compensation based on a fixed function of a roll angle of said vehicle and a height of a global navigation satellite system (GNSS) antenna disposed on said vehicle;

computing a sidehill tracking compensation based on a variable sidehill tracking function of said roll angle, said variable sidehill tracking function from a sidehill tracking error at least partly due to implement sidehill drift; and

determining a compensated crosstrack error based on said desired implement path, GNSS position measurements derived from GNSS signals received in said GNSS antenna, said roll height compensation and said tracking compensation;

said compensated crosstrack error for use for steering said vehicle in order to guide said implement to said desired path.

15. The method of claim 14, wherein:

said height is the height of said GNSS antenna above ground.

16. The method of claim 14, further comprising:

providing said sidehill tracking function for computing values of said tracking compensation corresponding to values of said roll angle, respectively, for compensating said tracking error between an actual implement path and said desired vehicle path when said vehicle having said roll angle is steered for minimizing said compensated crosstrack error.

17. The method of claim 14, further comprising:

providing said sidehill tracking function for providing a best fit between several values of said tracking compensation computed from several values of said roll angle, respectively and values of said tracking error measured at said several values of said roll angle.

18. The method of claim 14, further comprising:

steering said vehicle in order to minimize said compensated crosstrack error.

19. The method of claim 14, further comprising:

providing a time constant to said tracking compensation for causing said compensated crosstrack error to have a slower response to changes in said roll angle than to changes in a crosstrack error between said desired implement path and a GNSS-measured path determined with said GNSS position measurements.

20. The method of claim 14, further comprising:

editing said sidehill tracking function according to a current said tracking error and a current said roll angle for computing said sidehill tracking compensation for compensating for said current tracking error for said current roll angle.

21. The method of claim 20, further comprising:

issuing a function freeze signal to said tracking learn computer; and

wherein;

editing said sidehill tracking function includes determining said current tracking error at said function freeze signal.

22. The method of claim 20, wherein:

editing said sidehill tracking function includes re-calculating one or more coefficients of said function.

23. The method of claim 20, wherein:

editing said sidehill tracking function includes determining an order for said function.

24. The method of claim 14, further comprising:

editing said sidehill tracking function for minimizing a current said compensated crosstrack error for a current path of said vehicle.

25. The method of claim 14, further comprising:

editing said sidehill tracking function for a best fit of differences between several values for said sidehill tracking compensation for several values for said roll angle, respectively, and several values for said tracking error for said several values of said roll angle for providing a current said sidehill tracking compensation for said current roll angle.

26. The method of claim 14, further comprising:

adding a nudge difference to said compensated crosstrack error for providing a current said compensated crosstrack error;

measuring a current said tracking error from said nudge difference or said current compensated crosstrack error; and

using said current tracking error and a current said roll angle for editing said sidehill tracking function.