Attitude change kalman filter measurement apparatus and method

• US 6,859,727 B2
• Filed: 01/08/2003
• Issued: 02/22/2005
• Est. Priority Date: 01/08/2003
• Status: Expired due to Term

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Vallot, Lawrence C., Lund, Christopher A., Bye, Charles T.
• Primary Examiner(s): Camby, Richard M.
• Application Number:
  US10/338,415
• Publication Number:
  US 20040133346A1
• Time in Patent Office: 776 Days
• Field of Search: 701/208, 701/209, 701/210, 701/213, 701/214, 701/220, 701/221, 701/222, 342/357.02, 342/357.14, 342/357.11, 342/394, 342/442
• US Class Current: 701/210
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems

Abstract

A navigation system includes a Kalman filter to compensate for bias errors in inertial sensing elements. An observed pitch, roll or heading change is input to the Kalman filter either from an aiding source or when the navigation system is in a known condition. The Kalman filter generates a correction signal that is provided to the navigation computation system.

Claims

1. An apparatus for correction of bias errors in a navigation system, comprising:

a Kalman filter connected to the navigation system to receive attitude and heading signals from the navigation system, said Kalman filter including;

a delay element connected to receive the heading signal and produce therefrom a delayed heading signal over an update interval,

a signal combining element operable to subtract the delayed heading signal from the heading signal and produce an inertial heading change signal;

a Kalman filter engine connected to receive said inertial attitude and heading change signals, said Kalman filter engine having an output connected to send a navigation correction signal to the navigation system.

2. A navigation system for a body, comprising:

inertial sensors having outputs from which signals are provided corresponding to inertial changes in the body;

a navigation computation portion connected to receive the signals from said inertial sensors and producing a navigation signal; and

a Kalman filter portion connected to receive the navigation signal, said Kalman filter being operable to respond to a measured condition of the body and from said measured condition generate a correction signal for input to said navigation computation portion, said measured condition of the body being a change in at least one of heading and attitude of the body.

3. A navigation system for a body, comprising:

inertial sensors having outputs from which signals are provided corresponding to inertial changes in the body;

a navigation computation portion connected to receive the signals from said inertial sensors and producing a navigation signal;

a Kalman filter portion connected to receive the navigation signal, said Kalman filter being operable to respond to a condition of the body and from said condition generate a correction signal for input to said navigation computation portion;

a summing unit receiving said correction signal from said Kalman filter and producing a summed signal at an output; and

a signal combining unit having a subtracting unit connected to receive said summed signal at a subtracting input and to receive the signals from said inertial sensors at an adding input, said signal combining unit having an output connected to said navigation computation portion.

4. A navigation system for a body, comprising:

inertial sensors having outputs from which signals are provided corresponding to inertial changes in the body;

a navigation computation portion connected to receive the signals from said inertial sensors and producing a navigation signal;

a Kalman filter portion connected to receive the navigation signal, said Kalman filter being operable to respond to a condition of the body and from said condition generate a correction signal for input to said navigation computation portion;

wherein said Kalman filter includes;

a delay element connected to receive the heading signal and produce therefrom a delayed heading signal over an update interval,

a signal combining element operable to subtract the delayed heading signal from the heading signal and produce an inertial heading change signal;

a Kalman filter engine connected to receive said inertial heading change signal, said Kalman filter engine having an output connected to send a navigation correction signal to the navigation system.

5. A navigation system as claimed in claim 4, further comprising:

a summing unit in said Kalman filter portion having an input connected to an output of said Kalman filter engine, said summing unit being operable to sum heading resets over the update interval, said summing unit having an output which is connected so as to be subtracted from said inertial heading change signal.

6. A navigation system as claimed in claim 4, further comprising:

an input for an aiding device, said input receiving an observed heading change signal.

7. A navigation system as claimed in claim 6, wherein said observed heading change signal is from a heading change sensor.

8. A navigation system as claimed in claim 6, wherein said observed heading change signal taken while the body is stationary and the heading change signal is zero.

9. A method for correction of bias errors in a navigation system of a body, comprising the steps of:

receiving inertial sensor signals from inertia sensors mounted on said body;

computing navigation information to generate a heading signal;

applying a time delay corresponding to an update interval to said heading signal;

subtracting said time delayed heading signal from said heading signal to produce an inertial heading change over said update interval;

performing a Kalman filtering on said inertial heading change over said update interval to produce heading resets;

summing all heading resets over the update interval to produce a summed resets signal;

subtracting said summed resets signal from said inertial heading change over said update interval;

applying said heading resets to said computing navigation information step;

summing said resets signal to produce a bias correction parameter signal; and

subtracting said bias correction parameter signal from said inertial sensor signals.

10. A method as claimed in claim 9, further comprising the step of:

performing said steps of claim 9 while the body is stationary.

11. A method as claimed in claim 9, further comprising:

subtracting an observed heading change signal from said inertial heading change signal before said step of performing said Kalman filtering step.

12. A method as claimed in claim 11, wherein said observed heading change signal is received from an aiding source.

13. A method as claimed in claim 12, wherein said aiding source is a master inertial navigation system.

14. A method as claimed in claim 11, wherein said observed heading change is zero while the body is stationary.

15. An apparatus for correction of gyro bias errors in a navigation system, comprising:

a filter connected to receive signals from the navigation system, said filter using change in attitude or heading information to generate a correction signal; and

an output of said filter connected to said navigation system to provide said correction signal for correction of gyro bias errors.