Multiple-antenna GNSS control system and method

1. A GNSS guidance and roll compensation method for autosteering a vehicle with multiple GNSS antennas, a guidance processor including a central processing unit (CPU) and an autosteering subsystem, which method comprises the steps of:

mounting said antennas in a fixed, constrained-geometry relation on said vehicle;

acquiring GNSS ranging signals at said antennas;

computing with said receiver GNSS ranging data using said GNSS ranging signals as input;

computing with said CPU a position and a heading for the vehicle using said GNSS ranging data as input from said receiver;

computing with said CPU vehicle roll data in real time from ranging differences at said GNSS antennas;

computing roll correction values from said vehicle roll data;

applying said roll correction values to steering commands output from said CPU;

steering said vehicle with said autosteering subsystem utilizing said steering command and said roll correction values; and

applying a delay phase shift to said roll correction values.

2. The method according to claim 1 , which includes the additional steps of: determining an antenna height consisting of a height of said antennas above ground level; and calibrating said correction values based on an antenna height and a residual GNSS positioning error.

3. The method according to claim 2 , which includes additional steps of increasing said roll correction values to compensate for residual GNSS positioning error.

4. The method according to claim 2 , which includes the additional steps of:

preprogramming said GNSS system with a predetermined, fixed roll correction value; and

subtracting from said fixed roll correction values a roll error in real time.

5. A moving baseline GNSS guidance method for an articulated equipment unit comprising a vehicle and an implement connected thereto by an articulated connection, said equipment unit being equipped with a GNSS receiver, a GNSS guidance processor including a central processing unit (CPU) and a steering subsystem, said method comprising the steps of:

mounting a vehicle GNSS antenna on said vehicle;

mounting an implement GNSS antenna on said implement;

receiving GNSS ranging signals with said antennas;

inputting said GNSS ranging signals to said receiver;

computing GNSS positioning data corresponding to said antenna positions with said receiver using said GNSS ranging signals;

inputting said GNSS positioning data from said GNSS receiver to said CPU;

defining with said CPU a moving baseline between said antennas using the relative GNSS-defined positions of said antennas in real time;

varying said moving baseline distance and direction in real time corresponding to said vehicle and implement relative movements;

computing steering commands with said CPU and outputting said steering commands to said autosteer subsystem; and

steering said vehicle and/or said implement with said steering commands.

6. The method according to claim 5 wherein said vehicle antenna comprises a first vehicle antenna, which method includes the additional steps of:

providing a second vehicle antenna mounted on said vehicle in fixed relation relative to said first vehicle antenna;

receiving GNSS ranging signals with said second vehicle antenna;

inputting said second vehicle antenna GNSS ranging signals to said receiver;

calculating GNSS positioning data for said second vehicle antenna with said GNSS receiver;

inputting said second vehicle antenna GNSS positioning data from said GNSS receiver to said CPU;

computing in real time with said CPU GNSS-defined vehicle attitude, heading and rate-of-turn GNSS data using said GNSS positioning data from said vehicle antennas;

varying said moving baseline distance and direction in real time corresponding to said vehicle and implement relative movements;

computing steering commands with said CPU and outputting said steering commands to said autosteer subsystem; and

guiding said vehicle with said positioning, vehicle attitude, heading and rate-of-turn GNSS-defined data.

7. The method according to claim 6 , which includes the additional steps of:

providing a second implement antenna mounted on said implement in fixed relation relative to said first implement antenna;

receiving GNSS ranging signals with said second implement antenna;

inputting said second implement antenna GNSS ranging signals to said receiver;

calculating GNSS positioning data for said second implement antenna with said GNSS receiver; and

inputting said second implement antenna GNSS positioning data from said GNSS receiver to said CPU.

8. The method according to claim 7 wherein said implement includes an implement guidance system, which method includes the additional steps of:

providing an implement guidance system connected to said implement;

computing with said CPU in real time implement guidance signals; and

outputting from said CPU to said implement guidance system said implement guidance signals; and

guiding said implement with said implement guidance system utilizing said implement guidance signals.

9. The method according to claim 5 , which includes the additional steps of:

defining with said GNSS guidance system a multiposition tail comprising multiple GNSS positions trailing said vehicle and a predetermined time or distance spacing;

saving with said CPU the most recent said GNSS positions along said tail; and

deleting from said GNSS guidance system older positions.

10. The method according to claim 9 , which includes the additional steps of:

saving in said GNSS guidance system a guide path for said implement;

computing in real time with said CPU a crosstrack error of said implement relative to said guidepath utilizing said GNSS vehicle and implement positioning data, vehicle heading and vehicle rate-of-turn;

compensating with said vehicle steering subsystem for said crosstrack error; and

guiding said implement along said guidepath.

11. A real-time kinematic (RTK) GNSS guidance method for autosteering a vehicle with multiple GNSS antennas, a guidance processor including a central processing unit (CPU) and an autosteering subsystem, which method utilizes carrier-phase GNSS signals from a base station at a predetermined location and comprises the steps of:

mounting said antennas in a fixed, constrained-geometry relation on said vehicle;

transmitting code and carrier phase GNSS positioning data from the base station to said vehicle-mounted antennas;

acquiring GNSS ranging signals at said antennas;

computing with said receiver GNSS ranging data using said GNSS ranging signals as input;

computing with said CPU a position and a heading for the vehicle using said GNSS ranging data as input from said receiver;

determining the relative locations and relative ambiguities of the vehicle-mounted antennas utilizing an attitude solution taking advantage of known constraints in geometry and/or a common clock or synchronized clocks;

forming single or double difference equations utilizing said GNSS positioning data and solving for the global ambiguities utilizing the relative antenna locations and/or a common clock or synchronized clocks and relative ambiguities; and

computing in real-time with said CPU steering signals utilizing said GNSS positioning and heading data and said relative locations of said vehicle GNSS receiver's and said relative ambiguities and the known attitude solution; and

providing as input from said CPU to said steering subsystem said steering signals; and

steering said vehicle with said steering signals as input from said CPU.

12. The method according to claim 11 , which includes the additional steps of:

storing with said GNSS guidance system an attitude solution comprising locations and ambiguities;

time-tag matching the stored attitude solution information with GNSS information from the base station; and

storing off current GNSS carrier phase observations for time-tag matching the stored current GNSS carrier phase observations with GNSS information from the base station.

13. The method according to claim 11 , which includes the additional steps of:

providing multiple antennas and said base; and

canceling multipath GNSS signal errors at the base.

14. A GNSS guidance method for primary and secondary rover vehicles each equipped with a GNSS receiver, a GNSS guidance processor including a central processing unit (CPU) and a steering subsystem, said method comprising the steps of:

mounting a vehicle GNSS antenna on each said vehicle;

receiving GNSS ranging signals with said antennas;

inputting said GNSS ranging signals to said receiver;

computing GNSS positioning data corresponding to said antenna positions with said receiver using said GNSS ranging signals;

inputting said GNSS positioning data from said GNSS receiver to said CPU;

transmitting GNSS corrections signals from said base transceiver to said rover vehicle receivers;

transmitting from said primary rover vehicle identification, position, time and speed information to said secondary rover vehicle;

computing steering commands with said CPU and outputting said steering commands to said autosteer subsystem;

steering said vehicle and/or said implement with said steering commands;

transmitting differential corrections from said base transceiver and master rover GNSS data over the same radio link or an additional radio link;

transmitting said differential corrections at predetermined time intervals; and

transmitting said master rover GNSS data between said differential correction transmissions.

15. The method according to claim 14 , which includes the additional step of said secondary rover storing said primary rover information corresponding to a multiple position tail consisting of the most recent master rover information transmissions; and

deleting from said secondary rover GNSS system older master rover GNSS data.