Pedometer device and step detection method using an algorithm for self-adaptive computation of acceleration thresholds

• US 7,463,997 B2
• Filed: 10/02/2006
• Issued: 12/09/2008
• Est. Priority Date: 10/03/2005
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Binda, Ivo, Pasolini, Fabio
• Primary Examiner(s): Nghiem; Michael P
• Application Number:
  US11/537,933
• Publication Number:
  US 20070143068A1
• Time in Patent Office: 799 Days
• Field of Search: 702/141, 702150-154, 702/158, 702/160, 600/595, 734/90, 735/10
• US Class Current: 702/160
• CPC Class Codes: G01C 22/006 Pedometers

Abstract

In a pedometer device for detecting and counting steps of a user on foot, an accelerometer sensor detects a vertical acceleration generated during the step. A processing unit, connected to the accelerometer sensor, processes an acceleration signal relating to the acceleration in order to detect the occurrence of a step, and in particular compares the acceleration signal with a first reference threshold. The processing unit automatically adapts the first reference threshold as a function of the acceleration signal. In particular, the processing unit modifies the first reference threshold as a function of an envelope of the amplitude of the acceleration signal.

Claims

1. A pedometer device for detecting and counting steps of a user, the device comprising:

an accelerometer sensor configured to detect an acceleration generated during a step; and

a processing unit coupled to said accelerometer sensor, and configured to process an acceleration signal relating to said acceleration to detect an occurrence of the step, said processing unit including;

first comparator means for comparing said acceleration signal with a first reference threshold, said processing unit being configured to detect the occurrence of the step based on a result of said comparing between said acceleration signal and said first reference threshold, and

threshold-adaptation means for modifying, at each acquisition of a new sample of said acceleration signal, said first reference threshold as a function of an envelope of an amplitude of said acceleration signal.

2. The device according to claim 1, wherein said processing unit further includes envelope-calculation means for calculating said envelope of said amplitude of said acceleration signal, and wherein said threshold-adaptation means modifies automatically said first reference threshold as said function of said envelope so that said first reference threshold follows a variation of said envelope.

3. The device according to claim 2, wherein said threshold-adaptation means are configured to assign to said first reference threshold a value equal to a fraction of a value of said envelope, said fraction being smaller than 1.

4. The device according to claim 3, wherein said fraction is approximately 0.65.

5. The device according to claim 3, wherein said processing unit further includes:

length-estimation means for determining an estimated step length at each step detection, as a function of a maximum value of said first reference threshold; and

distance-calculation means for calculating a distance traveled by said user as a function of said estimated step length.

6. The device according to claim 1, wherein said processing unit further includes:

mean-value calculation means for calculating a d.c. component of the acceleration detected by said accelerometer sensor;

for eliminating said d.c. component from said acceleration; and

for producing said acceleration signal.

7. The device according to claim 1, wherein said accelerometer sensor includes a micro-electromechanical system (MEMS) sensor, and said acceleration is directed along a vertical axis.

8. The device according to claim 7, wherein said processing unit further includes axis-determination means for determining a vertical axis of detection of said accelerometer sensor, along which said acceleration is to be detected.

9. A pedometer device for detecting and counting steps of a user, the device comprising:

an accelerometer sensor configured to detect an acceleration generated during a step; and

a processing unit coupled to said accelerometer sensor, and configured to process an acceleration signal relating to said acceleration to detect an occurrence of the step, said processing unit including;

first comparator means for comparing said acceleration signal with a first reference threshold, said processing unit being configured to detect the occurrence of the step based on a result of said comparing between said acceleration signal and said first reference threshold, and

threshold-adaptation means for modifying said first reference threshold as a function of said acceleration signal,

wherein said first reference threshold has positive values, and wherein said processing unit further includes second comparator means for comparing said acceleration signal with a second reference threshold having negative values; and

wherein said threshold-adaptation means are further for modifying automatically said second reference threshold as a function of an envelope of an amplitude of said acceleration signal.

10. The device according to claim 9, wherein said first and second reference thresholds have, in absolute value, a respective lower-limit value, and wherein said processing unit further includes setting means for setting said lower-limit value.

11. The device according to claim 9, wherein said processing unit is configured to detect the occurrence of the step, when said acceleration signal has a given relation with said first reference threshold, and subsequently with said second reference threshold within a given time interval.

12. An electronic mobile phone, comprising:

a casing; and

a pedometer device housed in said casing to detect and count steps of a user, the pedometer device including;

an accelerometer sensor configured to detect an acceleration generated during a step; and

a processing unit coupled to said accelerometer sensor, and configured to process an acceleration signal relating to said acceleration to detect an occurrence of the step, said processing unit including;

first comparator means for comparing said acceleration signal with a first reference threshold, said processing unit being configured to detect the occurrence of the step based on a result of said comparing between said acceleration signal and said first reference threshold, and

threshold-adaptation means for modifying, at each acquisition of a new sample of said acceleration signal, said first reference threshold as a function of an envelope of an amplitude of said acceleration signal.

13. The mobile phone according to claim 12, wherein said processing unit further includes envelope-calculation means for calculating said envelope of said amplitude of said acceleration signal, and wherein said threshold-adaptation means modifies automatically said first reference threshold as said function of said envelope so that said first reference threshold follows a variation of said envelope.

14. The mobile phone according to claim 12, wherein said processing unit further includes:

mean-value calculation means for calculating a d.c. component of the acceleration detected by said accelerometer sensor;

for eliminating said d.c. component from said acceleration; and

for producing said acceleration signal.

15. The mobile phone of claim 12, further comprising:

a circuit board on which said accelerometer sensor and processing unit are mounted;

a casing to house said circuit board;

a display screen arranged to be visible from outside of said casing and configured to display information corresponding to said pedometer device; and

an interface coupled to said pedometer device to communicate data with said pedometer device.

16. An electronic mobile phone, comprising:

a casing; and

a pedometer device housed in said casing to detect and count steps of a user, the pedometer device including;

an accelerometer sensor configured to detect an acceleration generated during a step; and

a processing unit coupled to said accelerometer sensor, and configured to process an acceleration signal relating to said acceleration to detect an occurrence of the step, said processing unit including;

first comparator means for comparing said acceleration signal with a first reference threshold, said processing unit being configured to detect the occurrence of the step based on a result of said comparing between said acceleration signal and said first reference threshold, and

threshold-adaptation means for modifying said first reference threshold as a function of said acceleration signal,

wherein said first reference threshold has positive values, and wherein said processing unit farther includes second comparator means for comparing said acceleration signal with a second reference threshold having negative values; and

wherein said threshold-adaptation means are further for modifying automatically said second reference threshold as a function of an envelope of an amplitude of said acceleration signal.

17. The mobile phone according to claim 16, wherein said first and second reference thresholds have, in absolute value, a respective lower-limit value, and wherein said processing unit further includes setting means for setting said lower-limit value.

18. A step detection method for detecting steps in a gait of a user, the method comprising:

producing an acceleration signal relating to an acceleration generated during a step; and

processing said acceleration signal to detect an occurrence of the step, said processing including;

comparing said acceleration signal with a first reference threshold to detect the occurrence of the step based on a result of said comparing between said acceleration signal and said first reference threshold, and

modifying, at each acquisition of a new sample of said acceleration signal, said first reference threshold as a function of an envelope of an amplitude of said acceleration signal.

19. The method according to claim 18, wherein the processing further includes calculating said envelope of said amplitude of said acceleration signal, and wherein the modifying includes modifying automatically said first reference threshold as said function of said envelope so that said first reference threshold follows a variation of said envelope.

20. The method according to claim 19, wherein the modifying includes assigning to said first reference threshold a value equal to a fraction of a value of said first envelope, said fraction being smaller than 1.

21. The method according to claim 20, wherein the fraction is approximately 0.65.

22. The method according to claim 20, wherein the processing further includes:

determining an estimated step length at each step detection, as a function of a maximum value of said first reference threshold; and

calculating a distance traveled by said user as a function of said estimated step length.

23. The method according to claim 18, wherein producing an acceleration signal includes:

calculating a d.c. component of said acceleration; and

eliminating said d.c. component from said acceleration to produce said acceleration signal.

24. The method according to claim 18, wherein producing the acceleration signal includes determining a vertical axis of detection along which said acceleration is to be detected.

25. A step detection method for detecting steps in a gait of a user, the method comprising:

producing an acceleration signal relating to an acceleration generated during a step; and

processing said acceleration signal to detect an occurrence of the step, said processing including;

comparing said acceleration signal with a first reference threshold to detect the occurrence of the step based on a result of said comparing between said acceleration signal and said first reference threshold, and

modifying said first reference threshold as a function of said acceleration signal,

wherein said first reference threshold has positive values; and

wherein the processing further includes comparing said acceleration signal with a second reference threshold having negative values; and

the modifying further including modifying automatically said second reference threshold as a function of an envelope of said acceleration signal.

26. The method according to claim 25, wherein said first and second reference thresholds have, in absolute value, a respective lower-limit value, and wherein the processing includes setting said positive and negative lower-limit values.

27. The method according to claim 25, wherein the processing includes detecting the occurrence of the step, when said acceleration signal has a given relation with said first reference threshold, and subsequently with said second reference threshold within a given time interval.

28. A pedometer device to detect and count steps of a user, the device comprising:

an accelerometer sensor configured to detect an acceleration generated during a step; and

a processing unit coupled to said accelerometer sensor, and configured to process an acceleration signal relating to said acceleration to detect an occurrence of the step, said processing unit further is configured to;

compare said acceleration signal with a first reference threshold, and

modify said first reference threshold as a function of said acceleration signal,

wherein said first reference threshold has positive values, and wherein said processing unit is further configured to compare said acceleration signal with a second reference threshold having negative values, and further configured to modify automatically said second reference threshold as a function of an envelope of an amplitude of said acceleration signal.

29. The device according to claim 28 wherein said first and second reference thresholds have, in absolute value, a respective lower-limit value, and wherein said processing unit is further configured to set said lower-limit value.

30. The device according to claim 28 wherein said processing unit is configured to detect the occurrence of the step, when said acceleration signal has a given relation with said first reference threshold, and subsequently with said second reference threshold within a given time interval.