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

• US 9,121,714 B2
• Filed: 02/14/2014
• Issued: 09/01/2015
• 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:
  US14/180,488
• Publication Number:
  US 20140236479A1
• Time in Patent Office: 564 Days
• Field of Search: 701/472
• US Class Current: 1/1
• 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. An electronic circuit for use with a personal accelerometer comprising:

input lines for respective accelerometer signals;

a nonvolatile memory having stored representations of instructions to generate a vector average of acceleration signal and a varying magnitude of acceleration signal, and to electronically correlate a sliding window of the respective acceleration signals with the magnitude of acceleration signal; and

a processor circuit coupled with the input lines and programmably operable in response to the instructions in the nonvolatile memory for at least addition and multiplication and conditional operations, thereby to effectuate the instructions and to electronically process at least some part of the signals to produce an estimation of attitude angle signal.

2. The electronic circuit claimed in claim 1 in which the processor circuit is operable to execute a search that electronically rotates the at least part of the acceleration signals and estimates a parameter of the acceleration 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.

3. The electronic circuit claimed in claim 2 in which the processor 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 vertical direction and lateral user direction.

4. The electronic circuit claimed in claim 2 in which the processor circuit is operable to execute a vector-average on the at least part of the acceleration signals to determine a direction related to gravity, and to use such determination to resolve an up/down sense of the vertical direction.

5. The electronic circuit claimed in claim 2 in which the processor 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.

6. The electronic circuit claimed in claim 2 in which the processor 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.

7. The electronic circuit claimed in claim 1 in which the processor 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.

8. The electronic circuit claimed in claim 1 in which the processor circuit is operable to execute a vector-average on the at least part of the acceleration signals to estimate a direction related to gravity, whereby to sense an orientation with respect to the environment.

9. The electronic circuit claimed in claim 8 in which the processor circuit is further operable to execute a search in a horizontal plane substantially perpendicular to the estimated direction related to gravity in which that search electronically rotates the at least part of the acceleration 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.

10. The electronic circuit claimed in claim 9 in which the processor circuit is further operable to estimate the attitude by electronically deriving an angle in a horizontal plane and 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 device heading direction.

11. The electronic circuit claimed in claim 9 in which the processor circuit is further operable to electronically estimate a direction related to gravity and electronically execute a search in a plane substantially perpendicular to the estimated direction related to gravity in which 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 motion with respect to the accelerometer as a direction along which such parameter is minimized.

12. The electronic circuit claimed in claim 11 in which the processor circuit is further operable to estimate the attitude angle using that direction along which such parameter is minimized.

13. The electronic circuit claimed in claim 1 in which the processor circuit is operable to filter the respective acceleration 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.

14. The electronic circuit claimed in claim 1 in which the processor circuit is further operable to perform a walking-step detection processing and to deliver signals that jointly represent a path of user motion based on a heading, attitude and step detection.

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

16. The electronic circuit claimed in claim 1 further comprising at least one unit coupled with the processor circuit and selected from the group consisting of 1) electronic compass,) gyroscope, 3) inertial sensor, 4) magnetic sensor, 5) micro-electromechanical accelerometer.