METHOD TO IMPROVE LEVELING PERFORMANCE IN NAVIGATION SYSTEMS

• US 20130103344A1
• Filed: 05/04/2012
• Published: 04/25/2013
• Est. Priority Date: 10/25/2011
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Bye, Charles T., Liu, Fan, Morgan, Kenneth Steven
• Granted Patent: US 10,444,017 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: G01C 21/183 Compensation of inertial measurements, e.g. for temperature effects

Abstract

An attitude estimator system is provided. The attitude estimator system includes a navigation system, a Kalman filter, and a form observations module. The navigation system receives input from a first accelerometer and gyroscope, a second accelerometer and gyroscope, and a third accelerometer and gyroscope. The form observations module receives input from at least one high performance accelerometer and/or gyroscope; forms and outputs at least one of velocity-derived observations and attitude-derived observations. The Kalman filter processes by at least one of: inputting the velocity-derived observations formed in the form observations module, rotating the velocity-derived observation into a sensor-frame, and zeroing gains associated with at least one low performance accelerometer and/or gyroscope; or inputting the attitude-derived observations that are based on output from at least one of the first high performance accelerometer, the first high performance gyroscope, and the second high performance accelerometer.

Claims

1. An attitude estimator system, comprising:

a navigation system to output navigation data;

a Kalman filter to output Kalman filter feedback to the navigation system; and

a form observations module executable by a processor, wherein the navigation system receives input from a first high performance accelerometer and a first high performance gyroscope aligned to a first sensor-frame-level axis, from a second high performance accelerometer and a second gyroscope aligned to a second sensor-frame-level axis, and from a third low performance accelerometer and a third low performance gyroscope aligned to a sensor-frame Z axis, wherein the form observations module;

receives input from at least one of the first high performance accelerometer, the first high performance gyroscope, and the second high performance accelerometer,

forms at least one of velocity-derived observations and attitude-derived observations, and

outputs the at least one of velocity-derived observations and attitude-derived observations to the Kalman filter, and

wherein the Kalman filter processes the input from the form observations module by at least one of;

inputting the velocity-derived observations formed in the form observations module, rotating the velocity-derived observation into a sensor-frame, and zeroing gains associated with at least one of the third low performance accelerometer, and the third low performance gyroscope; and

inputting the attitude-derived observations formed in the form observations module, the attitude-derived observations being based on output from at least one of the first high performance accelerometer, the first high performance gyroscope, and the second high performance accelerometer.

2. The attitude estimator system of claim 1, wherein the second gyroscope aligned to the second sensor-frame-level axis is a second high performance gyroscope, and wherein the form observations module receives input from at least one of the first high performance accelerometer, the first high performance gyroscope, the second high performance accelerometer, and the second high performance gyroscope.

3. The attitude estimator system of claim 1, wherein the second gyroscope aligned to the second sensor-frame-level axis is a second low performance gyroscope, and wherein the Kalman filter processes the input from the form observations module by zeroing gains associated with at least one of the third low performance accelerometer, the second low performance gyroscope, and the third low performance gyroscope.

4. The attitude estimator system of claim 1, further comprising:

the first high performance accelerometer;

the first high performance gyroscope;

the second high performance accelerometer;

the second gyroscope;

the third low performance accelerometer;

the third low performance gyroscope; and

a sensor compensator, wherein the first high performance accelerometer, the first high performance gyroscope, the second high performance accelerometer, the second gyroscope, the third low performance accelerometer, and the third low performance gyroscope are communicatively coupled to output data to the sensor compensator, wherein the sensor compensator inputs the Kalman filter feedback from the Kalman filter and outputs compensated sensor data based on the Kalman filter feedback.

5. The attitude estimator system of claim 1, wherein the form observations module comprises;

a form observations module to input a reference value, to difference the reference value and a navigation input from the navigation system, and to output an observation to the Kalman filter based on the difference between the reference value and the navigation input.

6. The attitude estimator system of claim 5, wherein the Kalman filter includes:

a module to rotate an error into the sensor-frame; and

a compute Kalman gains module to zero selected gains.

7. The attitude estimator system of claim 1, wherein the form observations module includes:

a compute attitude observation module; and

a form observations module, wherein the compute attitude observation module includes;

a first module to compute a reference roll and a reference pitch based on data from the first high performance accelerometer and the second high performance accelerometer;

a second module to determine a navigation heading based on the navigation data; and

a third module to compute a reference heading value based on;

the reference pitch input from the first module;

the navigation heading input from the second module;

an earth rate input from the second module; and

high accuracy gyro data from the first high performance gyroscope.

8. The attitude estimator system of claim 7, wherein the form observations module takes a difference between a navigation heading from the navigation system and the reference heading value from the third module and outputs an attitude observation to the Kalman filter.

9. The attitude estimator system of claim 1, wherein the form observations module includes;

a compute velocity observation to input the navigation data from the navigation system, to input a reference velocity, and to form a navigation frame velocity observation, and

a compute attitude observation module including;

a compute reference attitude module to input sensor data from the first gyroscope and to output reference data, and

a module to form attitude observations, the module configured to difference the reference data and the navigation data, and to output an attitude observation to the Kalman filter.

10. The attitude estimator system of claim 1, further comprising:

the processor to execute the Kalman filter.

11. A method to improve performance of a navigation system communicatively coupled to a first high performance accelerometer and a first high performance gyroscope aligned to a first sensor-frame-level axis, a second high performance accelerometer and a second gyroscope aligned to a second sensor-frame-level axis, and a third low performance accelerometer and a third low performance gyroscope aligned to a third sensor frame axis, the method comprising:

computing at least one observation based on input to a form observations module from at least one of the first high performance gyroscope, the first high performance accelerometer, and the second high performance accelerometer;

outputting the at least one observation to a Kalman filter from the form observations module; and

outputting error corrections as Kalman filter feedback from the Kalman filter wherein degradation of the navigation system due to at least one of the third low performance accelerometer, and the third low performance gyroscope is reduced.

12. The method of claim 11, wherein the form observations module includes a compute reference attitude module and a module to form attitude observation, wherein computing the at least one observation based on input to the form observations module comprises:

computing a reference attitude direction cosine matrix at the compute reference attitude module based on data from at least one of the first high performance accelerometer, the first high performance, and the second high performance accelerometer;

inputting the reference attitude direction cosine matrix at the module to form attitude observation in the form observations module; and

computing an attitude observation at the module to form attitude observation, and wherein outputting at least one observation to the Kalman filter comprises;

outputting the attitude observation to the Kalman filter from the module to form attitude observation.

13. The method of claim 12, wherein the form observations module further includes a compute velocity observation module, wherein the computing the at least one observation further comprises:

differencing a navigation velocity from the navigation system and a reference velocity value, and wherein outputting at least one observation to the Kalman filter further comprises;

outputting a velocity observation to the Kalman filter from the compute velocity observation module.

14. The method of claim 11, wherein the form observations module includes a compute velocity observation module, wherein the computing the at least one observation based on input to a form observations module comprises:

differencing a navigation velocity from the navigation system and a reference velocity value, and wherein outputting at least one observation to the Kalman filter comprises;

outputting a velocity observation to the Kalman filter from the compute velocity observation module.

15. The method of claim 11, wherein the form observations module is a compute attitude observation module comprising a first module, a second module, and a third module, the method further comprising:

computing a reference roll value and a reference pitch value based on input to the first module from the first high performance accelerometer and the second high performance accelerometer;

computing a reference attitude value based on input to the second module from the first high performance gyroscope;

outputting a reference heading value from the third module; and

differencing a navigation heading from the navigation system and the reference heading value from the third module at a form observations module, wherein outputting the at least one observation to the Kalman filter comprises;

outputting an attitude observation from the form observations module to the Kalman filter.

16. A program product for improving performance of a navigation system communicatively coupled to a first high performance accelerometer and a first high performance gyroscope aligned to a first body-frame-level axis, a second high performance accelerometer and a second gyroscope aligned to a second body-frame-level axis, a third low performance accelerometer and a third low performance gyroscope aligned to a third body-frame axis, the program-product comprising a processor-readable medium on which program instructions are embodied, wherein the program instructions are operable, when executed by at least one processor included in an attitude estimator system communicatively coupled to the navigation system, to cause the attitude estimator system to:

compute at least one observation based on input to a form observations module from at least one of the first high performance gyroscope, the first high performance accelerometer, and the second high performance accelerometer;

output the at least one observation to a Kalman filter from the form observations module; and

output error corrections as Kalman filter feedback from the Kalman filter.

17. The program product of claim 16, wherein the form observations module includes a compute reference attitude module and a module to form attitude observation, wherein the program instructions are further operable, when executed by the at least one processor included in the attitude estimator system communicatively coupled to the navigation system, to cause the attitude estimator system to:

compute a reference attitude direction cosine matrix at the compute reference attitude module based on data from at least one of the first high performance accelerometer, the first high performance gyroscope, and the second high performance accelerometer;

input the reference attitude direction cosine matrix at the module to form attitude observation in the form observations module; and

compute an attitude observation at the module to form attitude observation.

18. The program product of claim 17, wherein the form observations module further includes a compute velocity observation module, wherein the program instructions are further operable, when executed by the at least one processor included in the attitude estimator system communicatively coupled to the navigation system, to cause the attitude estimator system to:

difference a navigation velocity from the navigation system and a reference velocity value, wherein the outputting the at least one observation to the Kalman filter comprises;

output a velocity observation to the Kalman filter from the compute velocity observation module.

19. The program product of claim 16, wherein the form observations module includes a compute velocity observation module, wherein the program instructions are further operable, when executed by the at least one processor included in the attitude estimator system communicatively coupled to the navigation system, to cause the attitude estimator system to:

difference a navigation velocity from the navigation system and a reference velocity value, wherein outputting at least one observation to the Kalman filter comprises;

output a velocity observation to the Kalman filter from the compute velocity observation module.

20. The program product of claim 16, wherein the form observations module is a compute attitude observation module comprising a first module, a second module, and a third module, wherein the program instructions are further operable, when executed by the at least one processor included in the attitude estimator system communicatively coupled to the navigation system, to cause the attitude estimator system to:

compute a reference roll value and a reference pitch value based on input to the first module from the first high performance accelerometer and the second high performance accelerometer;

compute a reference attitude value based on input to the second module from the first high performance gyroscope;

output a reference heading value from the third module; and

difference a navigation heading from the navigation system and the reference heading value from the third module at a form observations module, wherein outputting the at least one observation to the Kalman filter comprises;

output an attitude observation from the form observations module to the Kalman filter.