System for determining the orientation in space of a moving body relative to the earth

• US 6,223,105 B1
• Filed: 10/14/1999
• Issued: 04/24/2001
• Est. Priority Date: 10/14/1999
• Status: Expired due to Term

• Current Assignee: Garmin International, Inc. (Garmin Limited)
• Original Assignee: Seagull Technology, Inc.
• Inventors: Teague, E. Harrison
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US09/418,966
• Time in Patent Office: 558 Days
• Field of Search: 701/13, 701/4, 701/215, 701/213, 701/226, 701/200, 701/214, 244/158 R, 244/164, 244/171, 342/62, 342/357.11, 73/178 R
• US Class Current: 701/13
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G01S 19/53 Determining attitude
• CPC Class Codes: G01S 19/54 using carrier phase measurements; using long or short baseline interferometry

Abstract

Navigation satellite receiver measurements of the acceleration of a moving vehicle are used to derive valuable attitude information about the vehicle. Three-dimensional accelerometer measurements aboard the vehicle are used to determine the specific force vector in the bow frame. The navigation satellite receiver measurements allow determination of the specific force vector in the earth-fixed frame. The specific force vector measured in both vehicle and earth-fixed frames can be used with additional information to derive vehicle attitude.

Claims

1. A system for determining the heading, pitch, and roll of a moving vehicle relative to the earth, comprising:

a set of accelerometers carried aboard said moving vehicle for providing respective acceleration measurements for vehicle-frame x, y, z axes;

a calculator for determining a first specific force vector relative to said vehicle-frame x, y, z axes from said respective acceleration measurements;

a satellite navigation receiver for providing a second specific force vector; and

a computer for estimating a heading, pitch, and roll of said moving vehicle relative to the earth by matching said first and second specific force vectors and solving for a vehicle-frame attitude relative to earth;

wherein, a vehicle-frame attitude estimate is output.

2. The system of claim 1, wherein:

the satellite navigation receiver is a global positioning system (GPS) type and is carried aboard said moving vehicle.

3. The system of claim 1, wherein:

the satellite navigation;

receiver further provides clock and calendar time which is used to time-tag each of said first and second specific force vectors according to their respective times of calculation.

4. The system of claim 1, wherein:

the satellite navigation receiver further provides clock and calendar time which is used to correlate each of said first and second specific force vectors according to their respective times of calculation.

5. The system of claim 1, wherein:

the computer estimates said heading, pitch, and roll of said moving vehicle relative to the earth on-the-fly and in realtime as said first and second specific force vectors become available.

6. The system of claim 1, wherein:

the computer estimates past values of said heading, pitch, and roll of said moving vehicle relative to the earth during post-processing of stored values of said first and second specific force vectors.

7. The system of claim 1, wherein:

the satellite navigation receiver includes only one antenna.

8. A system for determining the heading, pitch, and roll of a moving vehicle relative to the earth, comprising:

a set of accelerometers carried aboard said moving vehicle for providing respective acceleration measurements for vehicle-frame x, y, z axes;

a calculator for determining a first specific force vector relative to said vehicle-frame x, y, z axes from said respective acceleration measurements;

a satellite navigation receiver for providing a second specific force vector; and

a computer for estimating a heading, pitch, and roll of said moving vehicle relative to the earth by matching said first and second specific force vectors and solving for a vehicle-frame attitude relative to earth which is then output;

wherein, the satellite navigation receiver provides said second specific force vectors by differential measurements of a series of positions over time.

9. A system for determining the heading, pitch, and roll of a moving vehicle relative to the earth, comprising:

a set of accelerometers carried aboard said moving vehicle for providing respective acceleration measurements for vehicle-frame x, y, z axes;

a calculator for determining a first specific force vector relative to said vehicle-frame x, y, z axes from said respective acceleration measurements;

a satellite navigation receiver for providing a second specific force vector; and

a computer for estimating a heading, pitch, and roll of said moving vehicle relative to the earth by matching said first and second specific force vectors and solving for a vehicle-frame attitude relative to earth which is then output;

wherein, the satellite navigation receiver provides said second specific force vectors derived directly from Doppler carrier-shift measurements of signals received from orbiting navigation satellite transmitters.

10. A method for determining the attitude of a moving vehicle relative to earth, the method comprising the steps of:

measuring a first specific force vector of said moving vehicle with respect to a vehicle-fixed frame (B-frame);

deriving a second specific force vector of vehicle with respect to an earth-fixed frame (N-frame );

inputting an auxiliary vector that is known in both said vehicle-fixed frame and said earth-fixed frame;

simultaneously calculating an attitude of said moving vehicle from said auxiliary vector, said first specific force vector, and said second specific force vector; and

outputting an attitude estimate that includes said heading, pitch, and roll estimates.

11. The method of claim 10, wherein:

the step of measuring a first specific force vector includes the use of accelerometers amounted aboard said moving vehicle; and

the step of deriving a second specific force vector includes the use of a navigation satellite receiver mounted aboard said moving vehicle, and which provides navigation solutions including velocity.

12. The method of claim 11, further comprising the step of:

making Doppler-shift measurements of the carrier signals of orbiting navigation satellites to determine a velocity of said moving vehicle in said earth-fixed frame, and using such to derive a measurement of said second specific force.

13. The method of claim 10, wherein:

the step of deriving a second specific force vector includes the use of a navigation satellite receiver mounted a board said moving vehicle, and which provides clock-calendar time to a computer; and

the step of simultaneously calculating heading, pitch, and roll estimates is done with a computer, wherein said clock-calendar time is used to time-match measurements of said first and second specific force vectors.