Attitude estimation for pedestrian navigation using low cost mems accelerometer in mobile applications, and processing methods, apparatus and systems

• US 8,694,251 B2
• Filed: 11/22/2011
• Issued: 04/08/2014
• Est. Priority Date: 11/25/2010
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Janardhanan, Jayawardan, Dutta, Goutam, Tripuraneni, Varun
• Primary Examiner(s): Cheung, Mary
• Assistant Examiner(s): MAZZARA, ANNE MARIE
• Application Number:
  US13/301,913
• Publication Number:
  US 20120136573A1
• Time in Patent Office: 868 Days
• Field of Search: 701/472, 701/512
• US Class Current: 701/512
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/183 Compensation of inertial measurements, e.g. for temperature effects
• CPC Class Codes: G01C 21/185 for gravity
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 22/006 Pedometers

Abstract

A user-heading determining system (10) for pedestrian use includes a multiple-axis accelerometer (110) having acceleration sensors; a device-heading sensor circuit (115) physically situated in a fixed relationship to the accelerometer (110); an electronic circuit (100) operable to generate signals representing components of acceleration sensed by the accelerometer (110) sensors, and to electronically process at least some part of the signals to produce an estimation of attitude of a user motion with respect to the accelerometer, and further to combine the attitude estimation (750, α) with a device heading estimation (770, ψ) responsive to the device-heading sensor circuit, to produce a user heading estimation (780); and an electronic display (190) responsive to the electronic circuit (100) to display information at least in part based on the user heading estimation. Other systems, circuits and processes are also disclosed.

Claims

1. A user-heading determining system for pedestrian use, the system comprising:

a multiple-axis accelerometer having acceleration sensors;

a device-heading sensor circuit physically situated in a fixed relationship to the accelerometer;

an electronic circuit operable to generate signals representing components of acceleration sensed by said accelerometer sensors, and to electronically process at least some part of the signals to produce an estimation of attitude of a user motion with respect to the accelerometer, and further to combine the attitude estimation with a device heading estimation responsive to said device-heading sensor circuit, to produce a user heading estimation; and

an electronic display responsive to said electronic circuit to display information at least in part based on said user heading estimation; and

wherein said electronic circuit is operable to execute a search that electronically rotates said at least part of the signals and estimates a parameter of the signals related to variance, and to estimate a vertical direction and a lateral user direction where the parameter is substantially maximum and where it is substantially minimum respectively.

2. The system claimed in claim 1 wherein said electronic circuit is operable to produce an estimation of attitude of user motion with respect to the accelerometer based on an electronic operation that estimates direction of user motion substantially perpendicular to both the aforesaid vertical direction and lateral user direction.

3. The system claimed in claim 1 wherein said electronic circuit is operable to execute a vector-average on said at least part of the signals whereby to determine a direction related to gravity, and to use such determination to resolve an up/down sense of the vertical direction.

4. The system claimed in claim 1 wherein said electronic circuit is operable to detect a sense of a leading or lagging relation between acceleration in the vertical direction and acceleration in a forward direction, and to use the detected sense of the relation to resolve whether the user motion is forward or backward.

5. The system claimed in claim 1 wherein said electronic circuit is operable to monitor for a phase difference between acceleration in the vertical direction and acceleration in a forward direction, and to generate a signal indicating consistency or not of the monitored phase difference with a pedestrian walking mode for the processing.

6. The system claimed in claim 1 wherein said electronic circuit is operable to estimate accelerations in multiple directions and to perform a walking-context determination responsive to a comparison of such estimated accelerations to process in different motion monitoring modes depending on the comparison.

7. The system claimed in claim 1 wherein said electronic circuit is operable to execute a vector-average on said at least part of the signals to estimate a direction related to gravity, whereby to sense an orientation of the sensors with respect to the environment.

8. The system claimed in claim 7 wherein said electronic circuit is further operable to execute a search in a horizontal plane substantially perpendicular to the estimated direction related to gravity wherein that search electronically rotates said at least part of the signals and estimates a parameter related to variance, and then to establish a forward direction of user motion with respect to the accelerometer as a direction along which such parameter corresponds to a maximum variance, whereby to determine the forward direction with respect to the device heading.

9. The system claimed in claim 8 wherein said electronic circuit is further operable to estimate the attitude substantially equal to an angle between a plane including both a forward direction and the vertical and another plane including both the vertical and a sensor oriented for pickup towards the heading.

10. The system claimed in claim 1 wherein said electronic circuit is operable to filter the respective acceleration component signals prior to and filter coupled to the attitude estimation using a filter selected from the group consisting of:

1) sliding window correlation,

     2) integration,

     3) bandpass filter passing human motion frequencies,

     4) polynomial filter smoothing human motion frequencies.

11. The system claimed in claim 1 wherein said electronic circuit is operable to generate a signal representing a varying magnitude of acceleration, and to electronically correlate a sliding window of the respective acceleration component signals with the magnitude of acceleration prior to the attitude estimation.

12. The system claimed in claim 1 wherein said electronic circuit is further operable to operable to electronically estimate a direction related to gravity and electronically execute a search in a horizontal plane substantially perpendicular to the estimated direction related to gravity wherein that search electronically rotates said at least part of the signals and estimates a parameter related to variance, and then determines a particular direction of user motion with respect to the accelerometer as a direction along which such parameter is minimized.

13. The system claimed in claim 12 wherein said electronic circuit is further operable to estimate the attitude as a function of that direction along which such parameter is minimized.

14. The system claimed in claim 1 wherein said electronic circuit is further operable to perform a walking-step detection process and to operate said display to visually represent a path of user motion based jointly on the user-heading estimation and the walking-step detection process.

15. The system claimed in claim 1 wherein said electronic circuit includes a memory and said electronic circuit is operable to store into said memory a time-window of data responsive to the signals and representing approximately a walking-stride of data for such processing.

16. The system claimed in claim 1 wherein device-heading sensor circuit includes at least one unit selected from the group consisting of 1) electronic compass, 2) gyroscope, 3) inertial sensor, 4) magnetic sensor.

17. The system claimed in claim 1 wherein said electronic circuit includes a nonvolatile memory substantially defining at least some of the aforesaid operations and a processor circuit coupled with said nonvolatile memory for electronic execution of the operations defined by said nonvolatile memory.