Methods and applications for altitude measurement and fusion of user context detection with elevation motion for personal navigation systems

• US 8,566,032 B2
• Filed: 10/30/2009
• Issued: 10/22/2013
• Est. Priority Date: 10/30/2009
• Status: Expired due to Fees

• Current Assignee: CSR Technology Holdings Inc. (Qualcomm, Inc.)
• Original Assignee: CSR Technology Holdings Inc. (Qualcomm, Inc.)
• Inventors: Chowdhary, Mahesh, Sharma, Manish, Pande, Ashutosh, Jain, Mahaveer, Narula, Gagan, Agarwal, Chinmay, Kumar, Arun, Paul, Kolin
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): Anwari, Maceeh
• Application Number:
  US12/609,582
• Publication Number:
  US 20110106449A1
• Time in Patent Office: 1,453 Days
• Field of Search: 701/214, 701/121
• US Class Current: 701/469
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled

Abstract

Methods and apparatuses for estimating a user'"'"'s altitude with respect to the mean sea level are provided. According to some aspects, the present invention is able to estimate altitude in both open sky as well as in degraded GPS signal environments such as dense urban canyon environments where GPS performance is affected by fewer available satellites and/or multipath error. According to other aspects, the present invention uses data from a pressure sensor to estimate altitude, either with or without the use of GPS aiding data. According to further aspects, estimated altitude is integrated with other types of dead reckoning data to provide user context detection pertaining to changes of altitude.

Claims

1. A method comprising:

receiving data corresponding to a user'"'"'s position in altitude;

filtering samples, to remove noise and smooth, of the user'"'"'s altitude data with at least two different order filters each in a time window of respectively different durations to obtain different numbers of filtered samples of the same altitude data corresponding to the two filters;

automatically determining the user'"'"'s context based on the filtered samples of the received altitude data, the context including whether the user'"'"'s altitude is changing, and if it is changing, a type of motion associated with the changing altitude.

2. A method according to claim 1, wherein the type of motion includes one of moving at the same altitude, moving on a ramp, stair or escalator, and riding an elevator.

3. A method according to claim 1, wherein the receiving step includes obtaining samples of data from a pressure sensor.

4. A method according to claim 3, wherein the step of receiving data further includes receiving additional information from an external source, and using the additional information to adjust the pressure sensor data.

5. A method according to claim 4, wherein the additional information includes approximate altitude based on the user'"'"'s location.

6. A method according to claim 4, wherein the additional information includes atmospheric conditions based on the user'"'"'s location.

7. A method according to claim 4, wherein the additional information includes indoor pressure conditions based on the user'"'"'s location.

8. A method according to claim 4, further comprising:

calibrating the pressure sensor using the additional information.

9. A method according to claim 3, further comprising:

receiving satellite positioning information, and

determining a navigation solution for the user using the received satellite positioning information and the altitude information, the navigation solution including estimated altitude.

10. A method according to claim 9, wherein the step of determining the navigation solution includes supplying the altitude information from the pressure sensor to a Kalman filter.

11. A method according to claim 1, wherein the different numbers of filtered samples of altitude data from the different time windows are compared against a threshold value to determine the type of motion associated with the changing altitude.

12. A method according to claim 11, wherein the automatically determining step further includes comparing the outputs of certain of the filters to determine that the person is moving on the same floor.

13. A method according to claim 11, wherein the automatically determining step further includes comparing the outputs of certain of the filters to determine that the person is moving on a ramp, staircase or escalator.

14. A method according to claim 11, wherein the automatically determining step further includes comparing the outputs of certain of the filters to determine that the person is moving on an elevator.

15. A method according to claim 11, further comprising comparing the outputs of certain of the filters to determine that altitude drift correction is needed.

16. A method according to claim 1, wherein the automatically determining step is further based on information about the user'"'"'s acceleration.

17. A navigation device comprising:

a radio frequency (RF) receiver adapted to provide position data;

a barometric pressure sensor adapted to provide altitude data; and

a processor communicatively coupled with the RF receiver and the barometric pressure sensor, the processor including at least two different order filters each adapted to filter, by removing noise and smoothing, the altitude data in a time window of respectively different duration to obtain different numbers of filtered samples of the same altitude data corresponding to the two filters, wherein the samples of altitude data determine whether a user'"'"'s altitude is changing, as well as the rate at which the altitude is changing.

18. The navigation device of claim 17, wherein the processor is further configured to:

use the position data to determine the user'"'"'s position while the RF receiver is providing reliable position data; and

use the altitude data from the pressure sensor to determine the user'"'"'s altitude when the RF receiver has stopped providing reliable position data.

19. The navigation device of claim 17, wherein the processor is further configured to determine a type of motion associated with the rate at which the user'"'"'s altitude is changing.

20. The navigation device of claim 19, wherein the different numbers of samples of altitude data from the different time windows are compared against a threshold value to determine the type of motion associated with the rate at which the user'"'"'s altitude is changing.

21. The navigation device of claim 20, wherein the processor compares outputs of the filters to determine that the user is moving on a same floor.

22. The navigation device of claim 20, wherein the processor compares outputs of the filters to determine that the user is moving on a ramp, staircase or escalator.

23. The navigation device of claim 20, wherein the processor compares outputs of the filters to determine that the user is moving on an elevator.

24. The navigation device of claim 20, wherein the processor compares outputs of the filters to determine that altitude drift correction is needed.