Method and apparatus for high accuracy relative motion determination using inertial sensors

• US 20060224321A1
• Filed: 01/27/2006
• Published: 10/05/2006
• Est. Priority Date: 03/29/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Ignagni, Mario, Vallot, Lawrence C., Lund, Christopher A., Soehren, Wayne A.
• Granted Patent: US 7,844,397 B2
• Time in Patent Office: Days
• US Class Current: 701/220
• CPC Class Codes: G01C 19/58 Turn-sensitive devices without moving masses
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/185 for gravity
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01C 23/005 Flight directors indicating arrangements specially adapted for rotary gyroscopes G01C19/32

Abstract

A relative navigation system including a first unit responsive to the motion of a first position, a second unit responsive to the motion of a second position and a processing unit that generates a relative navigation solution as a function of first unit information and second unit information. The generated relative navigation solution is indicative of at least one of: a relative position vector of the second position relative to the first position, a relative velocity of the second position relative to the first position, and a relative attitude of the first unit at the first position relative to the second unit at the second position.

Claims

1. A relative navigation system comprising:

a first unit responsive to the motion of a first position;

a second unit responsive to the motion of a second position; and

a processing unit that generates a relative navigation solution as a function of first unit information and second unit information, wherein the generated relative navigation solution is indicative of at least one of;

a relative position vector of the second position relative to the first position, a relative velocity of the second position relative to the first position, and a relative attitude of the first unit at the first position relative to the second unit at the second position.

2. The relative navigation system of claim 1, wherein the processing unit additionally generates the relative navigation solution by incorporating reference information, wherein the reference information is indicative of at least one of a nominal position of the second position relative to the first position and a nominal relative velocity of the second position relative to the first position and wherein the relative navigation solution comprises relative states.

3. The relative navigation system of claim 1, wherein the first unit comprises a first inertial measurement unit and the second unit comprises a second inertial measurement unit.

4. The relative navigation system of claim 1, wherein at least one of the first unit and the second unit is collocated with a radio-frequency antenna.

5. The navigation system of claim 1, wherein the first position, and the second position, are included in one of a flexible structure, two flexible structures, a semi-flexible structure, two semi-flexible structures, and a flexible structure and a semi-flexible structure.

6. A system comprising:

a first unit located at a first position, the first unit operable to generate first unit information that is responsive to a motion of the first position;

a second unit located at a second position nominally offset from the first position by a nominal lever-arm, the second unit operable to generate second unit information that is responsive to a motion of the second position; and

a processing unit operable to receive the first unit information from the first unit and the second unit information from the second unit, the processing unit additionally operable to generate compensated sensor information from the first unit information and the second unit information;

wherein the processing unit generates resets to relative states of a relative navigation solution as a function of the compensated sensor information and reference information,

wherein the compensated sensor information is generated from the first unit information and the second unit information and

wherein the reference information is indicative of at least one of the nominal lever-arm of the second position relative to the first position and a nominal relative velocity of the second position relative to the first position.

7. The system of claim 6, wherein the first unit is a first inertial measurement unit and the second unit is a second inertial measurement unit and wherein compensated sensor information is derived from inertial sensor data received from the first inertial measurement unit and inertial sensor data received from the second inertial measurement unit.

8. The system of claim 7, wherein the system is a relative navigation system, wherein at least one of the first unit and the second unit is collocated with a global positioning system (GPS) antenna and wherein the relative navigation system comprises a portion of a tightly-coupled GPS-aided navigational system.

9. The system of claim 7, wherein the system is a relative navigation system, wherein at least one of the first unit and the second unit is collocated with an electronic surveillance measurement (ESM) antenna and wherein the relative navigation system comprises a portion of a radiation source locating system.

10. The system of claim 6, wherein the processing unit comprises:

a data fusion algorithm;

a sensor compensation algorithm operable to generate the compensated sensor information from the first unit information and the second unit information; and

a relative navigation algorithm operable to;

receive the compensated sensor information from the sensor compensation algorithm;

receive the resets from the data fusion algorithm; and

generate the relative states as a function of at least the compensated sensor information,

wherein the data fusion algorithm is operable to;

receive the relative navigation solution and the reference information;

generate the resets based on the relative navigation solution and the reference information; and

output the resets to the relative navigation algorithm,

wherein the resets are corrective feedback used to control errors in the relative navigation solution.

11. The system of claim 10, wherein the processing unit further comprises:

a prefilter that receives the relative states and filters error information that is a function of at least the relative navigation solution.

12. The system of claim 11, wherein the prefilter comprises at least one of a first-order roll-off filter and a notch filter.

13. The system of claim 10, wherein the resets comprise algorithm resets and device resets, and where in the algorithm resets are corrective feedback used to control errors in the relative navigation solution and the device resets are corrective feedback used to control errors in one of the first unit and the second unit.

14. The system of claim 10, wherein the nominal lever-arm is a first lever-arm, the data fusion algorithm is a first data fusion algorithm, the relative navigation algorithm is a first relative navigation algorithm, the reference information is first reference information, the compensated sensor information is first compensated sensor information, the reference information is a first reference information, the resets are first resets and the relative states are first relative states and the relative navigation solution is a first relative navigation solution, the system further comprising:

a third unit located at a third position nominally offset from the first position by a second lever-arm and operable to generate third unit information that is indicative of at least one of a position of the third position and a motion of the third position; and

a second data fusion algorithm;

a second sensor compensation algorithm operable to generate a second compensated sensor information from the first unit information and the third position information; and

a second relative navigation algorithm operable to;

receive the second compensated sensor information from the second sensor compensation algorithm;

receive second resets from the second data fusion algorithm; and

generate second relative states as a function of at least the second compensated sensor information,

wherein the second data fusion algorithm is operable to;

receive a second relative navigation solution and a second reference information;

generate second resets based on the second relative navigation solution and the second reference information; and

output the second resets to the second relative navigation algorithm, wherein the resets are corrective feedback used to control errors in the second relative navigation solution.

15. The system of claim 14, where in the first unit is a first inertial measurement unit, the second unit is a second inertial measurement unit, and the third unit is a third inertial measurement unit and wherein the first compensated sensor information is derived from inertial sensor data received from the first inertial measurement unit and the second inertial measurement unit, and wherein second compensated sensor information is derived from the inertial sensor data received from the first inertial measurement unit and the third inertial measurement unit.

16. The system of claim 14, wherein the first relative states and second relative states are output from the processing unit for use in an external system.

17. The system of claim 16, wherein the external system is selected from a group comprising one of a navigation system, a structure monitoring system, a system to monitor a plurality of structures, an ultra tight coupling global positioning system inertial navigation system, an emitter location system, and combinations thereof.

18. The system of claim 6, wherein the reference information comprises a model of a nominal lever-arm including the first position and the second position.

19. The system of claim 6, wherein the motion of the first position comprises at least one of a velocity of the first position, an acceleration of the first position, and a rotation of the first position.

20. The system of claim 6, further comprising:

a plurality of units in addition to the first unit and the second unit, the plurality of units each located at a related position and each operable to generate unit information that is responsive to a motion of the unit, wherein each of the plurality of units exclusive of the first unit is located at a position nominally offset from the first position by a respective nominal lever-arm, and wherein each of the plurality of units, exclusive of the first unit, forms a pair of units with the first unit;

a plurality of relative navigation algorithms in the processing unit each associated with a respective pair of units and each relative navigation algorithm operable to generate relative states of a relative navigation solution for each pair of units; and

a plurality of data fusion algorithms in the processing unit each associated with one of the plurality of relative navigation algorithms and a respective pair of units, wherein each data fusion algorithm generates resets to the relative states of the relative navigation solution for each pair of units.

21. The system of claim 20, wherein the plurality of units are positioned on at least two dimensions of a semi-flexible structure, and wherein the plurality of the relative states are output from the processing unit for use in an external system to determine relative movements of the plurality of units on the semi-flexible structure.

22. A method comprising:

receiving sensor data from at least two sensors, wherein the sensor data is indicative of a motion of a first position and a motion of a second position;

compensating the received sensor data to generate compensated sensor information;

generating a relative navigation solution as a function of at least the compensated sensor information; and

generating corrective feedback as a function of at least the relative navigation solution and reference information.

23. The method of claim 22, wherein the corrective feedback is generated using a Kalman filter and wherein the corrective feedback is generated as a function of at least the compensated sensor information and reference information, wherein the reference information is indicative of at least one a nominal position of the second unit relative to the nominal position of the first unit and a nominal relative velocity of the second unit relative to the first unit.

24. The method of claim 22, further comprising outputting the relative navigation solution to an external system.

25. Software embodied on a storage medium comprising a plurality of program instructions operable to cause a processor to:

receive first unit information and second unit information from at least two sensors;

generate compensated sensor information as a function of at least the first unit information and the second unit information; and

generate a relative navigation solution as a function of at least the compensated sensor information.

26. The medium of claim 25, the medium further comprising a plurality of program instructions operable to cause a processor to:

receive the first unit information and the second unit information from a first sensor and a second sensor at a sensor compensation algorithm;

receive the relative navigation solution at a data fusion algorithm; and

output resets based on the received relative navigation solution from the data fusion algorithm to the relative navigation algorithm wherein the resets are corrective feedback used to control errors in the relative navigation solution.

27. The medium of claim 25, the medium further comprising a plurality of program instructions operable to cause a processor to:

generate a plurality of relative states for each of a pair of units formed between a plurality of units and the first unit at a respective relative navigation algorithm;

receive the plurality of relative states at a respective plurality of data fusion algorithms each associated with one of the relative navigation algorithms and a respective pair of units; and

generate a plurality of resets as a function of the plurality of relative states, wherein the compensated sensor information is indicative of at least one of motions of the positions relative to the first position, and

wherein the reference information is indicative of at least one of a nominal position of the positions relative to the first position and a nominal relative motion of the positions relative to the first position.

28. An apparatus comprising:

means for receiving sensor data from at least two sensors;

means for generating compensated sensor information as a function of at least the sensor data; and

means for receiving a relative navigation solution from the means for generating.

29. The apparatus of claim 28, wherein the means for generating comprise:

means for generating relative states as a function of at least the compensated sensor information; and

means for receiving resets from the means for receiving the relative navigation solution.

30. The apparatus of claim 28, wherein the means for generating comprise:

means for generating relative states for pairs of units; and

means for receiving a plurality of resets from the means for receiving the relative navigation solution.