Low-Complexity Tightly-Coupled Integration Filter for Step Detection in a Sensor-Assisted GNSS Receiver

• US 20130131983A1
• Filed: 01/18/2013
• Published: 05/23/2013
• Est. Priority Date: 09/24/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Roh, June Chul, Waters, Deric Wayne, Hosur, Srinath, Dutta, Goutam
• Granted Patent: US 8,645,062 B2
• Time in Patent Office: Days
• US Class Current: 701/472
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01C 22/006 Pedometers
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G06F 17/16 Matrix or vector computation , e.g. matrix-matrix or matrix-vector multiplication, matrix factorization matrix transposition G06F7/78

Abstract

Embodiments of the invention provide a step detection. An accelerometer measurement in the form of a multi-dimensional acceleration vector is obtained. The magnitude of the accelerometer measurement is filtered using a low pass filter. A threshold for a down-crossing is provided as is a threshold for an up-crossing. A step detection is triggered if the magnitude of the accelerometer measurement is greater than or equal to the threshold for an up-crossing.

Claims

1-41. -41. (canceled)

42. A method of step detection comprising:

obtaining accelerometer measurement a(k), where a(k) is multi-dimensional acceleration vector at a k-th sample;

filtering the magnitude of said accelerometer measurement a(k) using a low-pass filter;

providing a threshold for a down-crossing (dc);

providing a threshold for an up-crossing (uc); and

trigging a step detection if said magnitude of said accelerometer measurement |a(k)| is greater than or equal to said threshold for an up-crossing (uc).

43. The method of claim 42, wherein trigging a step detection if said magnitude of said accelerometer measurement la(k)1 is less than or equal to said threshold for an down-crossing (dc).

44. The method of claim 42, further comprising transitioning a static state if there is no up-crossing or down-crossing event for a predetermined time period.

45. The method of claim 42, further comprising transitioning to a down-crossing (dc) state if said magnitude of said accelerometer measurement |a(k)| is equal to or below said threshold for a down-crossing (dc).

46. The method of claim 42, further comprising:

providing a time window from time instance for the latest down-crossing; and

triggering a step detection when a transition to an up-crossing (uc) state from down-crossing (dc) state within said time window.

47. A method for pedestrian dead reckoning (PDR) data conversion for ease of global navigation satellite system/pedestrian dead reckoning (GNSS/PDR) integration by converting PDR position data to user velocity measured at a plurality of time instances where GNSS position/velocity estimates are available, said method comprising:

obtaining a heading and a step length for a previous step;

calculating a partial step using said heading and said step interval for said previous step;

obtaining a pedestrian dead reckoning (PDR) position at a current GNSS clock, comprising;

adding said partial step to said PDR position, if a step detection state is not in Static;

keeping said position for said previous step, if said step detection state is in Static; and

taking a difference between them to obtain said user velocity.

48. The method of claim 47, further comprising updating said position at the previous GNSS clock by interpolating with a plurality measured step instances.