Method and system for calibrating an IG/GP navigational system

• US 20020169553A1
• Filed: 09/28/2001
• Published: 11/14/2002
• Est. Priority Date: 05/11/2001
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Fibersense Technology Corp. (Northrop Grumman Corporation)
• Inventors: Humphrey, Ian, Perlmutter, Michael S.
• Granted Patent: US 6,622,091 B2
• Time in Patent Office: Days
• US Class Current: 701/214
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

A method of calibrating acceleration data signals from a set of accelerometers, and angular rate data signals from a set of gyroscopes within a combined GPS/IGS includes generating navigation data as a function of the acceleration data signals, the angular rate data signals, and prior navigation data. The method further includes combining the navigation data with GPS data via a Kalman filter, so as to produce corrected navigation data, navigation correction data, acceleration correction data and angular rate correction data. The method further includes modifying the acceleration data signals as a function of the acceleration correction data so as to calibrate the acceleration data signals, and modifying the angular rate data signals as a function of the angular rate correction data, so as to calibrate the angular data signals.

Claims

1. A method of calibrating acceleration data signals from a set of accelerometers, and angular rate data signals from a set of gyroscopes within a combined GPS/IGS, comprising:

generating navigation data as a function of the acceleration data signals, the angular rate data signals, and prior navigation data;

combining the navigation data with GPS data via a Kalman filter, so as to produce corrected navigation data, navigation correction data, acceleration correction data and angular rate correction data;

modifying the acceleration data signals as a function of the acceleration correction data so as to calibrate the acceleration data signals, and modifying the angular rate data signals as a function of the angular rate correction data, so as to calibrate the angular data signals.

2. A method according to claim 1, further including receiving the set of acceleration data signals from a set of three mutually orthogonal accelerometers.

3. A method according to claim 1, further including receiving the set of angular rate data signals from a set of three mutually orthogonal gyroscopes.

4. A method according to claim 1, wherein the acceleration correction data includes at least one acceleration bias correction factor, and modifying the acceleration data signals further includes adding the at least one acceleration bias correction factor to the acceleration data signals.

5. A method according to claim 4, wherein the acceleration correction data includes three acceleration bias correction factors corresponding to three accelerometer data signals, and modifying the acceleration data signals further includes adding each of the three acceleration bias correction factors to the corresponding acceleration data signal.

6. A method according to claim 4, further including storing the at least one acceleration bias correction factor in a memory device, subsequently retrieving the at least one acceleration bias correction factor from the memory device, and adding the retrieved acceleration bias correction factor to the corresponding acceleration data signal.

7. A method according to claim 1, wherein the angular rate correction data includes at least one gyroscope bias correction factor, and modifying the angular rate data signals further includes adding the at least one gyroscope bias correction factor to the angular rate data signals.

8. A method according to claim 7, wherein the angular rate correction data includes three gyroscope bias correction factors corresponding to three angular rate data signals, and modifying the angular rate data signals further includes adding each of the three gyroscope bias correction factors to the corresponding angular rate data signal.

9. A method according to claim 7, further including storing the at least one angular rate bias correction factor in a memory device, subsequently retrieving the at least one angular rate bias correction factor from the memory device, and adding the retrieved angular rate bias correction factor to the corresponding angular rate data signal.

10. A method according to claim 1, wherein the angular rate correction data includes at least one gyroscope scaling correction factor, and modifying the angular rate data signals further includes multiplying the at least one gyroscope scaling correction factor by the angular rate data signals.

11. A method according to claim 10, wherein the angular rate correction data includes three gyroscope scaling correction factors corresponding to three angular rate data signals, and modifying the angular rate data signals further includes multiplying each of the three gyroscope scaling correction factors by the corresponding angular rate data signal.

12. A method according to claim 10, further including storing the at least one gyroscope scaling correction factor in a memory device, subsequently retrieving the at least one gyroscope scaling correction factor from the memory device, and multiplying the retrieved gyroscope scaling correction factor to the corresponding angular rate data signal.

13. A method according to claim 1, wherein modifying the acceleration data signals further includes generating at least one acceleration bias correction factor being a predetermined function of (i) the acceleration correction data, (ii) the acceleration data signals, and (iii) parameters related to the accelerometers, and adding the at least one acceleration bias correction factor to the acceleration data signals.

14. A method according to claim 13, wherein generating at least one acceleration bias correction factor further includes combining (i) the acceleration correction data, (ii) the acceleration data signals, and (iii) one or more parameters related to the accelerometers as inputs to an algorithm.

15. A method according to claim 14, wherein the algorithm includes a sequence of operations executed by a processor.

16. A method according to claim 14, wherein the algorithm includes a logic circuit.

17. A method according to claim 13, wherein generating at least one acceleration bias correction factor further includes combining (i) the acceleration correction data, (ii) the acceleration data signals, and (iii) parameters related to the accelerometers as inputs to a look up table.

18. A method according to claim 1, wherein modifying the angular rate data signals further includes generating at least one gyroscope bias correction factor being a predetermined function of (i) the angular rate correction data, (ii) the angular data signals, and (iii) parameters related to the gyroscopes, and adding the at least one gyroscope bias correction factor to the angular rate data signals.

19. A method according to claim 18, wherein generating at least one gyroscope bias correction factor further includes combining (i) the angular rate correction data, (ii) the angular data signals, and (iii) parameters related to the gyroscopes as inputs to an algorithm.

20. A method according to claim 19, wherein the algorithm includes a sequence of operations executed by a processor.

21. A method according to claim 19, wherein the algorithm includes a logic circuit.

22. A method according to claim 18, wherein generating at least one gyroscope bias correction factor further includes combining (i) the angular rate correction data, (ii) the angular data signals, and (iii) parameters related to the gyroscopes as inputs to a look up table.

23. A method according to claim 1, wherein modifying the angular rate data signals further includes generating at least one gyroscope scaling correction factor being a predetermined function of (i) the angular rate correction data, (ii) the angular data signals, and (iii) parameters related to the gyroscopes, and multiplying the at least one gyroscope scaling correction factor by the angular rate data signals.

24. A method according to claim 23, wherein generating at least one gyroscope scaling correction factor further includes combining (i) the angular rate correction data, (ii) the angular data signals, and (iii) parameters related to the gyroscopes as inputs to an algorithm.

25. A method according to claim 24, wherein the algorithm includes a sequence of operations executed by a processor.

26. A method according to claim 24, wherein the algorithm includes a logic circuit.

27. A method according to claim 23, wherein generating at least one gyroscope scaling correction factor further includes combining (i) the angular rate correction data, (ii) the angular data signals, and (iii) parameters related to the gyroscopes as inputs to a look up table.

28. A method according to claim 1, wherein combining the navigation data with GPS data further includes receiving pseudo range rate data and pseudo rate data from the GPS and combining the pseudo range rate data and pseudo rate data with the navigation data.

30. A system according to claim 29, wherein the set of accelerometers is constructed and arranged so as to be mutually orthogonal.

31. A system according to claim 29, wherein the set of gyroscopes is constructed and arranged so as to be mutually orthogonal.

32. A system according to claim 29, wherein the acceleration correction data includes at least one acceleration bias correction factor, and the compensator includes an acceleration adder module for adding the at least one acceleration bias correction factor to the acceleration data signals.

33. A system according to claim 29, wherein the acceleration correction data includes three acceleration bias correction factors corresponding to the three accelerometer data signals, and the compensator includes an acceleration adder module for adding each of the three acceleration bias correction factors to the corresponding acceleration data signals.

34. A system according to claim 32, further including a memory device for storing the at least one acceleration bias correction factor.

35. A system according to claim 29, wherein the angular rate correction data includes at least one gyroscope bias correction factor, and the compensator includes a gyroscope adder module for adding the at least one gyroscope bias correction factor to the angular rate data signals.

36. A system according to claim 29, wherein the angular rate correction data includes three gyroscope bias correction factors, and the compensator includes a gyroscope adder module for adding the three gyroscope bias correction factors to the corresponding angular rate data signals.

37. A system according to claim 35, further including a memory device for storing the at least one gyroscope bias correction factor.

38. A system according to claim 29, wherein the angular rate correction data includes at least one gyroscope scaling correction factor, and the compensator includes a gyroscope multiplier module for multiplying the at least one gyroscope scaling correction factor by the angular rate data signals.

39. A system according to claim 29, wherein the angular rate correction data includes three gyroscope scaling correction factors, and the compensator includes a gyroscope multiplier module for multiplying the three gyroscope scaling correction factors by the corresponding angular rate data signals.

40. A system according to claim 38, further including a memory device for storing the at least one gyroscope scaling correction factor.

41. A system according to claim 29, further including an acceleration calculation module for generating at least one acceleration bias correction factor being a predetermined function of (i) the acceleration correction data, (ii) the acceleration data signals, and (iii) parameters related to the accelerometers.

42. A system according to claim 29, further including a gyroscope bias factor calculation module for generating at least one gyroscope bias correction factor being a predetermined function of (i) the angular rate correction data, (ii) the angular data signals, and (iii) parameters related to the gyroscopes.

43. A system according to claim 29, further including a gyroscope scaling factor calculation module for generating at least one gyroscope scaling correction factor being a predetermined function of (i) the angular rate correction data, (ii) the angular data signals, and (iii) parameters related to the gyroscopes.

29. A system for calibrating acceleration data signals from a set of accelerometers, and angular rate data signals from a set of gyroscopes within a combined GPS/IGS, comprising:

a navigation unit for generating navigation data as a function of the acceleration data signals, the angular rate data signals, and prior navigation data;

a Kalman filter for combining the navigation data with GPS data, so as to produce corrected navigation data, navigation correction data, acceleration correction data and angular rate correction data;

a compensator for modifying the acceleration data signals as a function of the acceleration correction data so as to calibrate the acceleration data signals, and modifying the angular rate data signals as a function of the angular rate correction data, so as to calibrate the angular data signals.

44. A system for calibrating acceleration data signals from a set of accelerometers, and angular rate data signals from a set of gyroscopes within a combined GPS/IGS, comprising:

means for generating navigation data as a function of the acceleration data signals, the angular rate data signals, and prior navigation data;

means for combining the navigation data with GPS data, so as to produce corrected navigation data, navigation correction data, acceleration correction data and angular rate correction data;

means for modifying the acceleration data signals as a function of the acceleration correction data so as to calibrate the acceleration data signals, and for modifying the angular rate data signals as a function of the angular rate correction data, so as to calibrate the angular data signals.