SYSTEM AND METHOD FOR ESTIMATING INERTIAL ACCELERATION BIAS ERRORS

• US 20080140315A1
• Filed: 12/12/2006
• Published: 06/12/2008
• Est. Priority Date: 12/12/2006
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Krogh, Steven B., Lapp, Tiffany R.
• Granted Patent: US 7,962,255 B2
• Time in Patent Office: Days
• US Class Current: 701/214
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled
• CPC Class Codes: G01S 19/52 Determining velocity

Abstract

A method for estimating inertial acceleration bias errors including obtaining uncorrected acceleration measurements on board a vehicle; obtaining independent position and independent velocity data of the vehicle; transforming the uncorrected acceleration measurements into a reference frame of the independent position and independent velocity data; blending the transformed acceleration measurements with the independent position and the independent velocity data to produce feedback errors; transforming the feedback errors into the reference frame of the acceleration measurements; multiplying the feedback errors by a gain and integrating to estimate the acceleration measurement bias errors.

Claims

1. A system for estimating inertial acceleration bias errors, comprising:

a first transformation module for receiving uncorrected acceleration measurements and transforming the measurements into a frame of independent position and independent velocity data;

a plurality of complementary filters for blending the transformed measurements with the independent position and the independent velocity data to produce feedback errors;

a second transformation module for transforming the feedback errors into the frame of the acceleration measurements and then multiplying the feedback errors by a gain and integrating to estimate the bias errors.

2. The system of claim 1, wherein the frame of the acceleration measurements are in a local frame of reference, having an along body, an across body and a normal component.

3. The system of claim 1, wherein the independent position and the independent velocity data are received from a GPS.

4. The system of claim 1, wherein the bias errors are used to estimate the position of an aircraft using an autopilot system for landing.

19. The system of claim 1, wherein the frame of the acceleration measurements are in a local frame of reference, having an along body, an across body and a normal component.

5. A method for estimating inertial acceleration bias errors, comprising:

obtaining uncorrected acceleration measurements on board a vehicle;

obtaining independent position and independent velocity data of the vehicle;

transforming the uncorrected acceleration measurements into a reference frame of the independent position and independent velocity data;

blending the transformed acceleration measurements with the independent position and the independent velocity data to produce feedback errors;

transforming the feedback errors into the reference frame of the acceleration measurements;

multiplying the feedback errors by a gain and integrating to estimate the acceleration measurement bias errors.

6. The method of claim 5, wherein the vehicle is an aircraft.

7. The method of claim 6, wherein the bias error estimates are used to correct acceleration measurements of the aircraft using an autopilot system for landing.

8. The method of claim 5, wherein a set of complementary filters blend the transformed measurements with the independent position and the independent velocity data.

9. The method of claim 8, wherein the set of complementary filters include an X-axis complementary filter, a Y-axis complementary filter, and a Z-axis complementary filter.

10. The method of claim 9, wherein the X-axis complementary filter estimates a feedback error in the X-axis, the Y-axis complementary filter estimates a feedback error in the Y-axis and the Z-axis complementary filter estimates a feedback error in the Z-axis.

11. The method of claim 5, wherein a first transformation module receives the acceleration measurements and transforms the measurements into the reference frame of the independent position and the independent velocity data.

12. The method of claim 5, wherein a second transformation module receives the feedback errors and transforms the feedback errors into the reference frame of the acceleration measurements.

13. The method of claim 5, wherein the independent position and the independent velocity data are received from a GPS.

14. The method of claim 5, wherein the independent position and independent velocity data are received from an Instrument Landing System.

15. The method of claim 5, wherein the frame of the acceleration measurements is the vehicle body axis.

16. A navigation system comprising:

a global positioning landing system with a differential GPS ground station;

a GPS receiver, in the landing system, for receiving differential position information of an aircraft and runway path coordinates;

an inertial reference unit for obtaining an aircraft'"'"'s uncorrected acceleration measurements;

a correction module for generating bias errors from the uncorrected acceleration measurements;

guidance software for determining guidance information for correcting the position of the aircraft; and

an autopilot system for receiving the guidance information and correcting the position of the aircraft.

17. The system of claim 16, wherein the guidance software processes the differential position information, the runway path coordinates signals and bias errors to determine the guidance information.

18. The system of claim 16, wherein the correction module comprises:

a first transformation module for receiving the uncorrected acceleration measurements and transforming the measurements into a frame of independent position and independent velocity data;

a plurality of complementary filters for blending the transformed measurements with the independent position and the independent velocity data to produce feedback errors;

a second transformation module for transforming the feedback errors into the frame of the acceleration measurements and then multiplying the feedback errors by a gain and integrating to estimate the bias errors.