Satellite based vehicle guidance control in straight and contour modes

• US 8,190,337 B2
• Filed: 10/14/2008
• Issued: 05/29/2012
• Est. Priority Date: 03/20/2003
• Status: Active Grant

• Current Assignee: Agjunction LLC (Kubota Corporation)
• Original Assignee: Hemisphere GPS LLC (Kubota Corporation)
• Inventors: McClure, John A., Collins, Dennis M., Timm, John T. E.
• Primary Examiner(s): Novosad, Christopher J.
• Application Number:
  US12/251,279
• Publication Number:
  US 20090099730A1
• Time in Patent Office: 1,323 Days
• Field of Search: 701/41, 701/50, 701/200, 701/213, 701/214, 701/23, 701/221, 250/221, 250/559.29, 342/357.06, 342/357.12, 342/357.14
• US Class Current: 701/50
• CPC Class Codes: A01B 69/008 automatic
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• 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

A method for steering an agricultural vehicle comprising: receiving global positioning system (GPS) data including position and velocity information corresponding to at least one of a position, velocity, and course of the vehicle; receiving a yaw rate signal; and computing a compensated heading, the compensated heading comprising a blend of the yaw rate signal with heading information based on the GPS data. For each desired swath comprising a plurality of desired positions and desired headings, the method also comprises: computing an actual track and a cross track error from the desired swath based on the compensated heading and the position; calculating a desired radius of curvature to arrive at the desired track with a desired heading; and generating a steering command based on the desired radius of curvature to a steering mechanism, the steering mechanism configured to direct the vehicle.

Claims

1. A method for steering an agricultural vehicle including the steps of:

receiving global navigation satellite system (GNSS) data including position and velocity information corresponding to at least one of a position, velocity and course of said vehicle;

mounting a yaw gyroscope (gyro) on a steerable component of said vehicle;

calibrating said yaw gyro with said GNSS data;

receiving from said yaw gyro a yaw rate signal corresponding to a yaw rate of said vehicle;

computing a compensated heading for said vehicle based on an integration of said yaw rate signal, said compensated heading comprising a blend of said yaw rate signal with heading information based on said GNSS data, wherein said compensated heading is further dynamically calibrated based on said GNSS data; and

for each desired swath comprising a plurality of desired positions and desired headings;

computing an actual track and a cross track error from said desired swath based on said compensated heading and said position, wherein said position is compared with a selected desired position of said plurality of desired positions and said compensated heading is compared with a selected desired heading of said plurality of desired headings;

calculating a desired radius of curvature to arrive at said desired swath with a desired heading; and

generating a steering command based on said desired radius of curvature to a steering mechanism, said steering mechanism configured to direct said vehicle.

2. The method of claim 1, which includes the additional step of connecting said yaw gyro to a steerable wheel of said vehicle.

3. The method of claim 2, which includes the additional step of connecting said yaw gyro to a hub of said steerable wheel.

4. The method of claim 3, which includes the additional step of connecting said yaw gyro to a steering mechanism.

5. The method of claim 1 wherein said vehicle is articulated with front and back pivotally-interconnected vehicle sections and said yaw gyro is mounted on one of said sections.

6. The method of claim 1 which includes the additional steps of:

generating a steerable wheel angle signal with said gyro;

generating a ROT signal with said gyro;

providing said vehicle with a controller; and

receiving as inputs to said controller said wheel angle and ROT signals from said gyro.

7. The method of claim 6, which includes the additional step of filtering said gyro output.

8. The method of claim 1 wherein said desired radius of curvature calculating step includes generating radius of curvature data based on best fit algorithms from said GNSS data including a current position, a heading and a speed to a desired aim point and a desired heading, said aim point being at least one of:

on a straight-line with parallel guidance;

an interpolated point from a point of closest approach to a previously logged, stored or generated curved track;

a series of points defining an edge of a previously traveled swath; and

a data file of track points based on best fit algorithms.

9. The method of claim, 1, which includes the additional steps of:

receiving differential corrections for said GNSS data; and

correcting said GNSS data based on said differential corrections.

10. The method of claim 9 wherein said GNSS data includes at least one of carrier phase RTK corrections, satellite-based differential corrections and ground-based differential corrections.

11. The method of claim 1, which includes the additional steps of:

using a differential GNSS with multiple antennas optimized to provide additional accuracy and said GNSS data further including heading data and generating said compensated heading utilizing said GNSS data and said heading data.

12. The method of claim 1 wherein said dynamic calibration includes at least one of rate gyro bias error and scale factor error during operation and eliminates static initialization.

13. The method of claim 1, which includes the additional steps of:

generating a tilt angle for said vehicle based on at least one of a filtered accelerometer signal and roll signal which can be used to generate a cross track correction based on antenna rotation height to correct for slope induced error in said crosstrack error.

14. The method of claim 1, which includes the additional steps of:

reducing error in and along track velocity and position by rotating an east and north velocity from said GNSS data into a long track and cross track components using said compensated heading.

15. The method of claim 1, which includes the additional steps of:

generating a steering command to drive a hydraulic or electrically driven steering system of said vehicle based on a difference between said desired curvature to reach and aim point, a current speed of said vehicle and a rate of turn of said vehicle.

16. The method of claim 1, which includes the additional steps of:

offsetting said desired swath to match differences in spacing of existing tracks to compensate for spacing errors therein;

compensating for features in fields with a step in a nominal spacing of parallel guidance lines by offsetting said desired line to align with a current position; and

determining in real-time a slope at a current position and application of a swath width adjustment to optimize real ground coverage to yield correct spacing between swaths and additional ground coverage.

17. A system for steering an agricultural vehicle with a steerable component, which system includes:

a GNSS receiver including an RF converter and a multi-channel tracking device;

and antenna connected to the RF converter;

a controller including a microprocessor;

said controller receiving GNSS data input from said receiver;

a steering subsystem including autosteering logic, an electric or hydraulic power source and steering linkage connected to said power source;

said steering subsystem receiving steering command input from said controller;

a wheel gyroscope (gyro) connected to said vehicle steerable component and providing wheel angle and rate-of-turn (ROT) input to said controller; and

said controller providing GNSS data as inputs to calibrate said wheel gyro.

18. The system according to claim 17, which includes:

said receiver receiving GNSS data corresponding to at least one of a position, velocity, and course of said vehicle;

said controller computing a compensated heading for said vehicle based on an integration of said yaw rate signal, said compensated heading comprising a blend of said yaw rate signal with heading information based on said GNSS data, wherein said compensated heading is further dynamically calibrated based on said GNSS data; and

for each desired swath comprising a plurality of desired positions and desired headings;

said controller computing an actual track and a cross track error from said desired swath based on said compensated heading and said position, wherein said position is compared with a selected desired position of said plurality of desired positions and said compensated heading is compared with a selected desired heading of said plurality of desired headings;

said controller calculating a desired radius of curvature to arrive at said desired track swath with a desired heading;

said controller generating radius of curvature data based on best fit algorithms from said GNSS data including a current position, a heading and a speed to a desired aim point and a desired heading;

said aim point being at least one of;

on a straight line with parallel guidance;

an interpolated point from a point of closest approach to a previously logged, stored or generated curved track;

a series of points defining an edge of a previously traveled swath; and

a data file of track points based on best fit algorithms; and

said controller generating a steering command based on said desired radius of curvature to a steering mechanism, said steering mechanism configured to direct said vehicle.