Navigation system and method for tracking the position of an object

• US 6,453,238 B1
• Filed: 09/15/2000
• Issued: 09/17/2002
• Est. Priority Date: 09/16/1999
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Chansarkar, Mangesh M., Brodie, Keith J., Rounds, Stephen F.
• Primary Examiner(s): Nguyen, Tan
• Assistant Examiner(s): Tran, Dalena
• Application Number:
  US09/662,559
• Time in Patent Office: 732 Days
• Field of Search: 701/216, 701/217, 701/214, 701/220, 701/300, 701/207, 701/224, 701/221, 340/988, 340/990, 340/995, 246/182.R, 246/357.03, 246/357.14, 246/457
• US Class Current: 701/216
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• 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 navigation system for tracking the position of an object includes a GPS receiver responsive to GPS signals for periodically providing navigation state measurement updates to a navigation processor. The system also includes a dead-reckoning sensor responsive to movement of the object for providing movement measurements to the navigation processor. The navigation processor determines object navigation states using the navigation state measurement updates and propagates the object navigation states between measurement updates using the movement measurements.

Claims

1. A navigation system for providing navigation information related to the movement of an object, comprising:

a global positioning satellite (GPS) receiver mounted to the object for receiving GPS signals and providing GPS measurements;

a navigation update unit receiving as input an updated dead-reckoning measurement and the GPS measurements, and providing as output navigation measurements and a modified dead-reckoning position measurement, wherein the navigation update unit comprises a filter for estimating changes in speed bias and speed scale factor from a measurement derived from an estimated velocity value;

at least one inertial sensor mounted to the object, sampling movement measurements and providing as output the movement measurements;

a sensor update unit receiving as input the navigation measurements and the movement measurements and providing as output position changes; and

a navigation propagation unit receiving as input the position change and the modified dead-reckoning measurement and providing as output the updated dead-reckoning measurement.

2. The system of claim 1 wherein the navigation measurements include measurement changes in at least one of heading, gyro bias, gyro scale factor, speed bias, and speed scale factor.

3. The system of claim 1 wherein the movement measurements include a gyro measurement, a speed measurement and a time measurement.

4. The system of claim 3 wherein the navigation measurements include measurement changes in at least one of heading, gyro bias, gyro scale factor, speed bias, and speed scale factor, and the sensor update unit comprises a first processor for processing the changes in heading, gyro bias, and gyro scale factor along with the gyro measurement to produce a heading measurement.

5. The system of claim 4 wherein the sensor update unit further comprises:

a second processor for processing the changes in speed bias and speed scale factor along with the speed measurement to produce changes in direction measurements.

6. The system of claim 5 wherein the direction measurements include a north/south measurement and an east/west measurement.

7. The system of claim 5 wherein the sensor update unit further comprises a time processing unit to process the time measurement to produce a change in time value.

8. The system of claim 1 wherein the navigation update unit comprises:

a first filter receiving as input the updated dead-reckoning measurement and the GPS measurements and providing as output an estimated velocity value;

a second filter for estimating changes in heading, gyro bias, and gyro scale factor from a first measurement derived from the estimated velocity value;

a position set unit for eliminating the updated dead-reckoning measurement when the measurement is bad; and

a process noise model that provides a process noise matrix to the primary filter.

9. The system of claim 1 wherein the updated dead-reckoning measurement may be derived by combining the position changes and the modified dead-reckoning measurement.

10. A method of tracking the position of an object, comprising:

periodically obtaining navigation state measurement updates;

processing the navigation state measurement updates to determine object navigation states;

obtaining movement measurements from a calibrated dead-reckoning sensor, where the calibration states include at least a speed bias, related to object movement; and

propagating the object navigation states between measurement updates using the movement measurements.

11. The method of claim 10 wherein the navigation state measurements comprises pseudorange and position data.

12. The method of claim 10 wherein the movement measurements comprise gyro measurement, speed measurement and time measurement.

13. A method of providing navigation information related to the movement of an object, comprising:

receiving GPS signals by a global positioning satellite (GPS) receiver mounted to the object and providing as output GPS measurements;

calculating navigation measurements and a modified dead-reckoning position measurement from an updated dead-reckoning measurement and the GPS measurements,

wherein a dead-reckoning sensor is calibrated with an estimate of at least a speed bias;

sampling movement measurements by at least one inertial sensor mounted to the object;

processing positioning changes from the navigation measurements and the movement measurements; and

propagating the updated dead-reckoning measurement calculated by the position change and the modified dead-reckoning measurement.

14. The method of claim 13 wherein calculating navigation measurements includes calculating measurement changes in at least one of heading, gyro bias, gyro scale factor, and speed scale factor.

15. The method of claim 14 wherein sampling movement measurements includes sampling at least one of a gyro measurement, a speed measurement and a time measurement.

16. The method of claim 14 wherein calculating navigation measurement comprises:

estimating a velocity value from the updated dead-reckoning measurement and the GPS measurements;

estimating heading changes from the estimated velocity value;

estimating speed changes from a measurement derived from the estimated velocity value;

eliminating the updated dead-reckoning measurement if it is bad; and

providing a process noise matrix, the process noise matrix for accommodating error sources that are not estimated when calculating navigation measurements.

17. The method of claim 16 wherein estimating heading changes includes estimating changes in at least one of heading, gyro bias, and gyro scale factor.

18. The method of claim 16 wherein estimating speed changes include estimating changes in at least one of speed bias and speed scale factor.

19. The method of claim 16 wherein eliminating the updated dead-reckoning measurement comprises determining if the update dead-reckoning measurement is bad by comparing the updated dead-reckoning measurement with a map-matched value.

20. A navigation system for tracking the position of an object, said system comprising:

a GPS receiver responsive to GPS signals for periodically providing navigation state measurement updates to a navigation processor; and

a dead-reckoning sensor responsive to movement of the object for providing movement measurements to the navigation processor wherein a dead-reckoning sensor is calibrated with a means for estimating at least a speed bias;

wherein the navigation processor determines object navigation states using the navigation state measurement updates and propagates the object navigation states between measurement updates using the movement measurements.

21. The system of claim 20 wherein the navigation state measurements comprises pseudorange and position data.

22. The system of claim 20 wherein the movement measurements comprises gyro measurement, speed measurement and time measurement.

23. The system of claim 20 wherein the navigation processor comprises:

a navigation update unit receiving as input an updated dead-reckoning measurement and the navigation state measurement updates, and providing as output navigation measurements and a modified dead-reckoning position measurement;

a sensor update unit receiving as input the navigation measurements and the movement measurements and providing as output position changes; and

a navigation propagation unit receiving as input the position changes and the modified dead-reckoning measurement and providing as output the updated dead-reckoning measurement.