Navigation system with minimal on-board processing

• US 20070100546A1
• Filed: 11/01/2005
• Published: 05/03/2007
• Est. Priority Date: 11/01/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Ring, Jeffrey
• Granted Patent: US 7,890,260 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems

Abstract

A navigation system that provides a position estimate. In one embodiment, a method includes integrating an acceleration estimate in each of three dimensions. Subtracting a GPS velocity in each of the dimensions from the integrated acceleration estimate in each dimension to determine a velocity noise error in each dimension. Filtering the velocity noise error in each dimension. Adding the filtered velocity noise error to the integrated acceleration estimate in each dimension to obtain a velocity estimate in each dimension. Integrating the velocity estimate in each dimension to determine an integrated velocity estimate in each dimension. Subtracting a GPS position in each dimension from the integrated velocity estimate in each dimension to determine a position noise error in each dimension. Filtering the position noise error in each dimension and adding the filtered position noise error in each dimension to the integrated velocity estimate to obtain a position estimate in each dimension.

Claims

1. A method of using a complementary filter comprising:

integrating an acceleration estimate to determine an integrated acceleration estimate;

subtracting a GPS velocity from the integrated acceleration estimate to determine a velocity noise error;

filtering the velocity noise error; and

adding the filtered velocity noise error to the integrated acceleration estimate to obtain a velocity estimate.

2. The method of claim 1, further comprising:

determining the acceleration estimate.

3. The method of claim 1, wherein filtering the velocity noise error further comprises:

filtering the velocity noise error at a select time constant based on a desired output.

4. The method of claim 1 further comprising:

integrating the velocity estimate to determine an integrated velocity estimate;

subtracting a GPS position from the integrated velocity estimate to determine a position noise error;

filtering the position noise error; and

adding the filtered position noise error to the integrated velocity estimate to obtain a position estimate.

5. The method of claim 4, further comprising:

determining the position estimate in three dimensions.

6. The method of claim 4, wherein filtering the position noise error further comprises:

filtering the position noise error at a time constant based on a desired output.

7. A method of determining a position estimate of an object;

the method comprising;

integrating an acceleration estimate in each of three dimensions to determine an integrated acceleration estimate for each of the dimensions;

subtracting a GPS velocity in each of the dimensions from the integrated acceleration estimate for each of the dimensions to determine a velocity noise error in each dimension;

filtering the velocity noise error in each dimension;

adding the filtered velocity noise error to the integrated acceleration estimate in each dimension to obtain a velocity estimate in each dimension;

integrating the velocity estimate in each dimension to determine an integrated velocity estimate in each dimension;

subtracting a GPS position in each dimension from the integrated velocity estimate in each dimension to determine a position noise error in each dimension;

filtering the position noise error in each dimension; and

adding the filtered position noise error in each dimension to the integrated velocity estimate to obtain a position estimate in each dimension.

8. The method of claim 7, further comprising:

determining the acceleration estimate in each of the three dimensions.

9. A machine readable medium having instructions stored thereon for generating a position estimate of an object in three dimensions, the method of the machine readable instructions for each dimension comprising:

integrating an acceleration estimate to determine an integrated acceleration estimate;

subtracting a GPS velocity from the integrated acceleration estimate to determine a velocity noise error;

filtering the velocity noise error;

adding the filtered velocity noise error to the integrated acceleration estimate to obtain a velocity estimate;

integrating the velocity estimate to determine a position;

subtracting a GPS position from the integrated velocity estimate to determine a position noise error;

filtering the position noise error; and

adding the filtered position noise error to the integrated velocity estimate to obtain a position estimate.

10. The machine readable instructions of claim 9 further comprising:

generating the acceleration estimate with an orbital acceleration equation.

11. A position estimator to estimate the position of an object in three dimensions, the determination of the position estimate in each dimension comprising:

a means to determine an acceleration estimate;

a means of integrating the acceleration estimate to determine an integrated acceleration estimate;

a means of subtracting a GPS velocity from the integrated acceleration estimate to determine a velocity noise error;

a means of filtering the velocity noise error;

a means of adding the filtered velocity noise error to the integrated acceleration estimate to obtain a velocity estimate;

a means of integrating the velocity estimate to determine an integrated velocity estimate;

a means of subtracting a GPS position from the integrated velocity estimate to determine a position noise error;

a means of filtering the position noise error; and

a means of adding the filtered position noise error to the integrated velocity estimate to obtain a position estimate.

12. A complementary filter position determining device, the device comprising:

a first filter circuit including,

a first integrator adapted to integrate an acceleration estimate to determine an integrated acceleration,

a first subtractor adapted to subtract a GPS velocity from the determined integrated acceleration estimate to determine a velocity noise error,

a first low pass filter adapted to filter the velocity noise error,

a first adder adapted to add the filtered velocity noise error to the integrated acceleration estimate to determine a velocity estimate; and

a second filter circuit including,

a second integrator adapted to integrate the velocity estimate to determine an integrated velocity estimate,

a second subtractor adapted to subtract a GPS position from the determined integrated velocity estimate to determine a position noise error,

a second low pass filter adapted to filter the position noise error, and

a second adder adapted to add the filtered position noise error to the integrated velocity estimate to determine a position estimate.

13. The device of claim 12, further comprising:

a clock adapted to provide a time reference for outputs of the device.

14. The device of claim 12, further comprising:

a GPS position input router adapted to receive the GPS position; and

a GPS velocity input router adapted to receive the GPS velocity.

15. The device of claim 12, further comprising:

an acceleration output adapted to provide the acceleration estimate to the first integrator.

16. The device of claim 15, wherein the acceleration output further comprises:

an orbital acceleration equation function adapted to determine the acceleration of a vehicle in orbit in three dimensions.

17. A position estimate system comprising:

an acceleration determining function adapted to determine an acceleration estimate of an object in a first, second and third dimension;

an x filter circuit adapted to determine a position estimate in the first dimension based at least in part on the acceleration estimate in the first dimension and a GPS acceleration in the first dimension;

an y filter circuit adapted to determine a position estimate in the second dimension based at least in part on the acceleration estimate in the second dimension and a GPS acceleration in the second dimension; and

an z filter circuit adapted to determine a position estimate in the third dimension based at least in part on the acceleration estimate in the third dimension and a GPS acceleration in the third dimension.

18. The position estimate system of claim 17, wherein the x filter circuit further comprises:

a first integrator adapted to integrate the acceleration estimate in the first dimension to determine an integrated acceleration in the first dimension;

a subtractor adapted to subtract the GPS velocity in the first dimension from the determined integrated acceleration estimate in the first dimension to determine a velocity noise error in the first dimension;

a low pass filter adapted to filter the velocity noise error in the first dimension;

an adder adapted to add the filtered velocity noise error in the first dimension to the integrated acceleration estimate in the first dimension to determine a velocity estimate in the first dimension;

a second integrator adapted to integrate the velocity estimate in the first dimension to determine an integrated velocity estimate in the first dimension;

a subtractor adapted to subtract the GPS position in the first dimension from the determined integrated velocity estimate in the first dimension to determine a position noise error in the first dimension;

a low pass filter adapted to filter the position noise error in the first dimension; and

an adder adapted to add the filtered position noise error in the first dimension to the integrated velocity estimate in the first dimension to determine a position estimate in the first dimension.

19. The position estimate system of claim 17, wherein the y filter circuit further comprises:

a first integrator adapted to integrate the acceleration estimate in the second dimension to determine an integrated acceleration in the second dimension;

a subtractor adapted to subtract the GPS velocity in the second dimension from the determined integrated acceleration estimate in the second dimension to determine a velocity noise error in the second dimension;

a low pass filter adapted to filter the velocity noise error in the second dimension;

an adder adapted to add the filtered velocity noise error in the second dimension to the integrated acceleration estimate in the second dimension to determine a velocity estimate in the second dimension;

a second integrator adapted to integrate the velocity estimate in the second dimension to determine an integrated velocity estimate in the second dimension;

a subtractor adapted to subtract the GPS position in the second dimension from the determined integrated velocity estimate in the second dimension to determine a position noise error in the second dimension;

a low pass filter adapted to filter the position noise error in the second dimension; and

an adder adapted to add the filtered position noise error in the second dimension to the integrated velocity estimate in the second dimension to determine a position estimate in the second dimension.

20. The position estimate system of claim 17, wherein the z filter circuit further comprises:

a first integrator adapted to integrate the acceleration estimate in the third dimension to determine an integrated acceleration in the third dimension;

a subtractor adapted to subtract the GPS velocity in the third dimension from the determined integrated acceleration estimate in the third dimension to determine a velocity noise error in the third dimension;

a low pass filter adapted to filter the velocity noise error in the third dimension;

an adder adapted to add the filtered velocity noise error in the third dimension to the integrated acceleration estimate in the third dimension to determine a velocity estimate in the third dimension;

a second integrator adapted to integrate the velocity estimate in the third dimension to determine a position in the third dimension;

an subtractor adapted to subtract the GPS position in the third dimension from the determined integrated velocity estimate in the third dimension to determine a position noise error in the third dimension;

a low pass filter adapted to filter the position noise error in the third dimension; and

an adder adapted to add the filtered position noise error in the third dimension to the integrated velocity estimate in the third dimension to determine a position estimate in the third dimension.