Multiple axis wrist worn pedometer

• US 10,197,416 B2
• Filed: 01/21/2015
• Issued: 02/05/2019
• Est. Priority Date: 01/21/2015
• Status: Active Grant

• Current Assignee: QuickLogic Corporation
• Original Assignee: QuickLogic Corporation
• Inventors: Yang, Duanduan, An, Dong, Wu, Ying
• Primary Examiner(s): Satanovsky, Alexander
• Assistant Examiner(s): Cordero, Lina M
• Application Number:
  US14/602,188
• Publication Number:
  US 20160209232A1
• Time in Patent Office: 1,476 Days
• Field of Search: 702141, 702150, 702160, 600500, 600301, 600309, 600310, 600324
• CPC Class Codes: G01C 21/12 executed aboard the object being navigated; Dead reckoning
• CPC Class Codes: G01C 22/006 Pedometers

Abstract

A wrist worn pedometer includes a multiple axis inertial sensor. Signals from each axis of the multiple axis inertial sensor are received and are separately analyzed to determine which axis is producing a stable periodic signal, which is selected as the counting axis, i.e., the axis to be used for counting steps. Additionally, the pedometer determines whether the counting axis is registering arm movement or footsteps. The user'"'"'s steps are counted based on the detected events, e.g., detected peaks or intervals between peaks, on the signal from the counting axis. One step per detected event is counted if the counting axis is registering footsteps and two steps per detected event are counted if the counting axis is registering arm movement. If the stability of the selected counting axis is lost, another axis is selected as the counting axis if it is producing a stable periodic signal.

Claims

1. A method for counting steps with a wrist worn pedometer, the method comprising:

receiving signals from each axis of a multiple axes inertial sensor in the wrist worn pedometer;

detecting peaks on each signal from each axis of the multiple axes inertial sensor;

calculating intervals between the detected peaks on each signal from each axis of the multiple axes inertial sensor;

determining a stability of the intervals between the detected peaks;

selecting a first axis with a stable periodic signal based on the stability of the intervals between the detected peaks;

counting steps based on detected events in the stable periodic signal for a predetermined number of detected events;

determining whether the first axis with the stable periodic signal registers arm movement or footsteps after the predetermined number of detected events;

revising a step count based on whether the first axis with the stable periodic signal registers arm movement or footsteps;

continuing to count steps based on additional detected events in the stable periodic signal, wherein one step per a detected event in the stable periodic signal is counted when the first axis with the stable periodic signal registers footsteps or two steps per the detected event are counted when the first axis with the stable periodic signal registers arm movement, and

displaying the step count on a display of the wrist worn pedometer.

2. The method of claim 1, wherein determining the stability of the intervals between the detected peaks comprises:

determining a standard deviation for a preset number of intervals between the detected peaks on each signal from each axis; and

comparing the standard deviation from each axis to a predetermined threshold to determine the first axis with the stable periodic signal.

3. The method of claim 1, wherein determining whether the first axis with the stable periodic signal registers arm movement or footsteps comprises:

determining an average or mean period between the detected peaks on the first axis;

determining a minimal periodic time length based on a shortest period from any axis having a stable periodic signal;

comparing the average or mean period between the detected peaks on the first axis with the minimal periodic time length, wherein the first axis is determined to register arm movement if the period between the detected peaks on the first axis is at least twice the minimal periodic time length.

4. The method of claim 1, wherein the detected events in the stable periodic signal are the detected peaks or the intervals between the detected peaks.

5. The method of claim 1, further comprising:

selecting a second axis with a stable periodic signal;

determining whether the second axis with the stable periodic signal registers arm movement or footsteps; and

wherein one step per the detected event in the stable periodic signal from the second axis is counted when the second axis with the stable periodic signal registers footsteps or two steps per the detected event in the stable periodic signal from the second axis are counted when the second axis with the stable periodic signal registers arm movement.

6. The method of claim 5, wherein selecting the second axis with the stable periodic signal comprises determining that the intervals between the detected peaks on a signal from the first axis are no longer stable before selecting the second axis with the stable periodic signal.

7. The method of claim 5, wherein selecting the second axis with the stable periodic signal comprises:

determining a stability of intervals between detected peaks on a signal from the first axis;

determining a stability of intervals between detected peaks on a signal from the second axis; and

determining that the stability of the intervals between the detected peaks on the signal from the second axis is greater than the stability of the intervals between the detected peaks on the signal from the first axis.

8. The method of claim 5, wherein determining whether the second axis with the stable periodic signal registers arm movement or footsteps comprises:

determining an average or mean period between the detected peaks on the second axis;

determining a minimal periodic time length based on a shortest period from any axis having a stable periodic signal;

comparing the average or mean period between the detected peaks on the second axis with the minimal periodic time length, wherein the second axis is determined to register arm movement if the period between the detected peaks on the second axis is at least twice the minimal periodic time length.

9. The method of claim 8, wherein when the first axis is determined to register arm movement, a two-step coefficient is set to a value of 2 or is otherwise set to a value of 1, and wherein determining whether the second axis with the stable periodic signal registers arm movement or footsteps further comprises:

setting an initial periodic time length as an average or mean period between the detected peaks on the first axis when the first axis is determined to produce a stable periodic signal;

comparing the average or mean period between the detected peaks on the second axis with the initial periodic time length, wherein a multiplication coefficient is set to 0.5 if the average or mean period between the detected peaks on the second axis is less than half of the initial periodic time length, the multiplication coefficient is set to 2 if the average or mean period between the detected peaks on the second axis is more than twice the initial periodic time length, or the multiplication coefficient is set to 1 otherwise; and

wherein one step per the detected event in the stable periodic signal from the second axis is counted when the second axis with the stable periodic signal registers footsteps or two steps per the detected event in the stable periodic signal from the second axis are counted when the second axis with the stable periodic signal registers arm movement by multiplying each detected event with a product of the two-step coefficient and the multiplication coefficient.

10. A pedometer for counting steps that is wrist worn, the pedometer comprising:

a multiple axes inertial sensor that provides signals for each axis;

a display for visually displaying a step count to a user of the pedometer, and

a processor coupled to the multiple axes inertial sensor and the display, the processor receives the signals from each axis of the multiple axes inertial sensor in the pedometer, the processor configured to detect peaks on each signal from each axis of the multiple axes inertial sensor;

calculate intervals between the detected peaks on each signal from each axis of the multiple axes inertial sensor;

determine a stability of the intervals between the detected peaks;

select a first axis with a stable periodic signal based on the stability of the intervals between the detected peaks;

count steps based on detected events in the stable periodic signal for a predetermined number of detected events;

determine whether the first axis with the stable periodic signal registers arm movement or footsteps after the predetermined number of detected events;

revise the step count based on whether the first axis with the stable periodic signal registers arm movement or footsteps;

continue to count steps based on additional detected events in the stable periodic signal, wherein one step per a detected event in the stable periodic signal is counted when the first axis with the stable periodic signal registers footsteps or two steps per the detected event are counted when the first axis with the stable periodic signal registers arm movement; and

cause the display to display the step count.

11. The pedometer of claim 10, wherein the processor is configured to determine the stability of the intervals between the detected peaks by being configured to determine a standard deviation for a preset number of intervals between the detected peaks on each signal from each axis;

and compare the standard deviation from each axis to a predetermined threshold to determine the first axis with the stable periodic signal.

12. The pedometer of claim 10, wherein the processor is configured to determine whether the first axis with the stable periodic signal registers arm movement or footsteps by being configured to:

determine an average or mean period between the detected peaks on the first axis;

determine a minimal periodic time length based on a shortest period from any axis having a stable periodic signal;

compare the average or mean period between the detected peaks on the first axis with the minimal periodic time length, wherein the first axis is determined to register arm movement if the period between the detected peaks on the first axis is at least twice the minimal periodic time length.

13. The pedometer of claim 10, wherein the detected events in the stable periodic signal are the detected peaks or the intervals between the detected peaks.

14. The pedometer of claim 10, wherein the processor is further configured to select a second axis with a stable periodic signal;

determine whether the second axis with the stable periodic signal registers arm movement or footsteps; and

wherein one step per the detected event in the stable periodic signal from the second axis is counted when the second axis with the stable periodic signal registers footsteps or two steps per the detected event in the stable periodic signal from the second axis are counted when the second axis with the stable periodic signal registers arm movement.

15. The pedometer of claim 14, wherein the processor is further configured to determine that the intervals between the detected peaks on a signal from the first axis are no longer stable before selecting the second axis with the stable periodic signal.

16. The pedometer of claim 14, wherein the processor is configured to select the second axis with the stable periodic signal by being configured to:

determine a stability of intervals between detected peaks on a signal from the first axis;

determine a stability of intervals between detected peaks on a signal from the second axis; and

determine that the stability of the intervals between the detected peaks on the signal from the second axis is greater than the stability of the intervals between the detected peaks on the signal from the first axis.

17. The pedometer of claim 14, wherein the processor is configured to determine whether the second axis with the stable periodic signal registers arm movement or footsteps by being configured to:

determine an average or mean period between the detected peaks on the second axis;

determine a minimal periodic time length based on a shortest period from any axis having a stable periodic signal;

compare the average or mean period between the detected peaks on the second axis with the minimal periodic time length, wherein the second axis is determined to register arm movement if the period between the detected peaks on the second axis is at least twice the minimal periodic time length.

18. The pedometer of claim 17, wherein the processor is configured to set a two-step coefficient to a value of 2 when the first axis is determined to register arm movement or to otherwise set the two-step coefficient to a value of 1, and wherein the processor is configured to determine whether the second axis with the stable periodic signal registers arm movement or footsteps by being further configured to:

set an initial periodic time length as an average or mean period between the detected peaks on the first axis when the first axis is determined to produce a stable periodic signal;

compare the average or mean period between the detected peaks on the second axis with the initial periodic time length, wherein the processor sets a multiplication coefficient to a value of 0.5 if the average or mean period between the detected peaks on the second axis is less than half of the initial periodic time length, the processor sets the multiplication coefficient to a value of 2 if the average or mean period between the detected peaks on the second axis is more than twice the initial periodic time length, or the processor sets the multiplication coefficient to a value of 1 otherwise; and

wherein one step per the detected event in the stable periodic signal from the second axis is counted when the second axis with the stable periodic signal registers footsteps or two steps per the detected event in the stable periodic signal from the second axis are counted when the second axis with the stable periodic signal registers arm movement by the processor being configured to multiply each detected event with a product of the two-step coefficient and the multiplication coefficient.