Adaptive Step Detection

• US 20130191069A1
• Filed: 01/18/2013
• Published: 07/25/2013
• Est. Priority Date: 01/19/2012
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Ravindran, Sourabh
• Granted Patent: US 11,054,279 B2
• Time in Patent Office: Days
• US Class Current: 702/160
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: G01C 22/006 Pedometers
• CPC Class Codes: G06F 1/163 Wearable computers, e.g. on a belt
• CPC Class Codes: G06F 1/1694 the I/O peripheral being a single or a set of motion sensors for pointer control or gesture input obtained by sensing movements of the portable computer

Abstract

A pedometer with a three-axis accelerometer provides reliable step counts while worn on the wrist. Three-axis accelerometer data is combined into a single combined data stream. Each positive slope region around an inflection point in the combined data stream that has positive slope, a magnitude that exceeds an amplitude threshold value and that spans a time period that exceeds a time threshold value is identified. Each negative slope region around an inflection point in the combined data stream that has negative slope, a magnitude that exceeds an amplitude threshold value and that spans a time period that exceeds a time threshold value is identified. A step count is incremented for each occurrence of an identified positive slope region that is separated by an identified negative slope region as a step.

Claims

1. A device for counting steps, the device comprising:

a three-axis accelerometer; and

a processor coupled to receive three-axis data from the three-axis accelerometer;

wherein the processor is configured to determine a number of steps taken by a user of the device by;

combining the three-axis data into a single combined data stream;

identifying each positive slope region around an inflection point in the combined data stream having a time period that exceeds a time threshold value, a positive slope, and a magnitude that exceeds an amplitude threshold value;

identifying each negative slope region around an inflection point in the combined data stream having a time period that exceeds a time threshold value, a negative slope, and a magnitude that exceeds an amplitude threshold value; and

counting each occurrence of an identified positive slope region that is separated by an identified negative slope region as a step.

2. The device of claim 1, wherein the processor is further configured to store the three axis data in three circular buffers, and to iteratively perform a finite impulse response (FIR) polynomial filter operation on the three axis data in each of the three circular buffers.

3. The device of claim 1, further comprising a transmitter coupled to the processor configured to transmit step information to a remote display device.

4. A method for counting steps using a three-axis accelerometer, the method comprising:

receiving three-axis data from the three-axis accelerometer;

combining the three-axis data into a single combined data stream;

identifying each positive slope region around an inflection point in the combined data stream having a time period that exceeds a time threshold value, a positive slope, and a magnitude that exceeds an amplitude threshold value;

identifying each negative slope region around an inflection point in the combined data stream having a time period that exceeds a time threshold value, a negative slope, and a magnitude that exceeds an amplitude threshold value;

incrementing a step count for each occurrence of an identified positive slope region that is separated by an identified negative slope region as a step; and

displaying the step count.

5. The method of claim 4, wherein the three axis data is received into three circular buffers, the method further comprises filtering the three-axis data in an iterative manner using a finite impulse response (FIR) polynomial filter operation on each axis of data in the three circular buffers.

6. A device for counting steps using a device worn by a user, the device comprising:

means for receiving three-axis data from a three-axis accelerometer in the device;

means for combining the three-axis data into a single combined data stream;

means for identifying each positive slope region around an inflection point in the combined data stream having a time period that exceeds a time threshold value, a positive slope, and a magnitude that exceeds an amplitude threshold value;

means for identifying each negative slope region around an inflection point in the combined data stream having a time period that exceeds a time threshold value, a negative slope, and a magnitude that exceeds an amplitude threshold value;

means for incrementing a step count for each occurrence of an identified positive slope region that is separated by an identified negative slope region as a step; and

means for displaying the step count.

7. The device of claim 6, further comprising means for filtering the three-axis data in an iterative manner using a finite impulse response (FIR) polynomial filter operation on each axis of data.