Method and device for measuring the progress of a moving person

• US 7,962,309 B2
• Filed: 12/19/2007
• Issued: 06/14/2011
• Est. Priority Date: 07/11/2007
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: VTI Technologies Oy (Murata Manufacturing Co Limited)
• Inventors: Meriheinä, Ulf
• Primary Examiner(s): Kundu; Sujoy K
• Application Number:
  US12/000,998
• Publication Number:
  US 20090018794A1
• Time in Patent Office: 1,273 Days
• Field of Search: 702/141, 702/160, 702/176, 702/182, 702/189, 734/90, 735/140.1
• US Class Current: 702/141
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/112 Gait analysis
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/6804 Garments; Clothes
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: G01C 21/10 by using measurements of speed or acceleration G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 22/006 Pedometers
• CPC Class Codes: G01P 15/00 Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
• CPC Class Codes: G01P 3/50 for measuring linear speed G01P3/56 takes precedence

Abstract

The invention relates to measuring devices to be used in physical measuring, and more particularly, to a method and a device for measuring the progress of a moving person. In the solution according to the invention the quantities describing the progress of the moving person can be calculated based on vertical acceleration values of the body measured by means of an acceleration sensor, and on the measured time. The invention aims at providing a solution, better and simpler than prior solutions, for measuring the progress of a moving person, which solution is applicable for use in a multitude of measuring solutions for ways of locomotion of various types.

Claims

1. A method for measuring the progress of a moving person, the method comprising:

calculating at least one of the following quantities describing the progress of the moving person;

speed, step rate, step count, step length, distance and way of progress, based on values of a vertical acceleration of a body of the moving person measured by an acceleration sensor over a measured time;

defining step cycle-specific characteristic maximum accelerations a_max falling within a positive half-cycle, during an acceleration stage, and correspondingly step cycle-specific characteristic minimum accelerations a_min falling within a negative half-cycle during a braking stage, based on measured values of the vertical acceleration of the body of the moving person; and

defining the step cycle-specific characteristic maximum acceleration values a_max mean values for each step cycle of digitally filtered acceleration sensor signals a_in over times selected during the positive half-cycle and the step cycle-specific characteristic minimum accelerations a_min as mean values for each step cycle of the digitally filtered acceleration sensor signals a_in over times selected during the negative half-cycle.

2. The method according to claim 1, wherein the determining comprises using a function for the digital filtering, wherein the function is:

a_out=a_in/√

{square root over ([1+(f/f₀)²)}],

where f is the frequency and f₀ is a suitably selected boundary frequency.

3. The method according to claim 1, further comprising:

defining the step cycle-specific characteristic maximum accelerations a_max as maxima for each step cycle of the signals a_in from the acceleration sensor filtered with digital weighting; and

defining the step cycle-specific characteristic minimum accelerations a_min as minima for each step cycle of the signals a_in from the acceleration sensor filtered with digital weighting.

4. The method according to claim 1, further comprising:

defining the step cycle-specific characteristic maximum accelerations a_max as mean values for each step cycle of the signals a_in from the acceleration sensor filtered with digital weighting over times selected during the positive half-cycle; and

defining the step cycle-specific characteristic minimum accelerations a_min as mean values for each step cycle of the signals a_in from the acceleration sensor filtered with digital weighting over times selected during the negative half-cycle.

5. The method according to claim 3, wherein a function used in the digital weighted filtering is:

a_out(n)=(1−

k)*a_out(n−

1)+a_in*k,

where n indicates the n;

th sample and k is the weighting factor.

6. The method according to claim 1, wherein the calculating comprises calculating the speed v based on the step cycle-specific characteristic maximum acceleration values a_max of the vertical acceleration as follows:

7. The method according to claim 1, wherein the calculating comprises calculating the speed v based on the step cycle-specific characteristic minimum accelerations a_min of the vertical acceleration as follows:

v≈

k·

√

{square root over (|a_min|)}.

8. The method according to claim 1, wherein the calculating comprises obtaining a time T_step used up for one step as a time interval between two equivalent points, such as a maximum, a minimum, or a point of exceeding or falling below a certain value, on an acceleration graph derived from the measured values of the vertical acceleration.

9. The method according to claim 8, further comprising:

calculating the step length s_step using the formula;

s_step=v*T_step.

10. The method according to claim 8, further comprising:

calculating the step rate f_step using the formula;

f_step=1/T_step.

11. The method according to claim 8, further comprising:

calculating the step count n based on a number n of equivalent points, such as a maximum, a minimum, or a point of exceeding or falling below a certain value, on the acceleration graph given by the measured values of vertical acceleration.

12. The method according to claim 8, further comprising:

calculating the distance covered s as a sum of the lengths of the steps;

13. The method according to claim 1, wherein the calculating comprises distinguishing between ways of progress selected from one of walking, running, and skiing, based on acceleration maximum and minimum, the step cycle-specific characteristic maximum and minimum acceleration values a_max and a_min and/or the step rate.

14. The method according to claim 13, wherein the calculating comprises making an individual calibration for each way of progress selected from one of running, walking, pole walking, or cross-country skiing.

15. The method according to claim 1, wherein the method is adapted for use in step-by-step navigation.

16. A device for measuring the progress of a moving person, the device being configured to

measure a minimum acceleration and time such, that at least one of the following quantities describing the progress of the moving person:

speed, step rate, step count, step length, distance and way of locomotion, is calculated based on values of a vertical acceleration of a body of the moving person measured by an acceleration sensor over a measured time;

determine step cycle-specific characteristic maximum accelerations a_max falling within a positive half-cycle, during an acceleration stage, and correspondingly, step cycle-specific characteristic minimum accelerations a_max falling within a negative half-cycle, during a braking stage, based on measured values of the vertical acceleration of the body of the moving person; and

determine the step cycle-specific characteristic maximum accelerations a_max as mean values for each step cycle of digitally filtered acceleration sensor signals a_in over times selected during the positive half-cycle and the step cycle-specific characteristic minimum accelerations a_min as mean values for each step cycle of the digitally filtered acceleration sensor signals a_in over times selected during the negative half-cycle.

17. The device according to claim 16, wherein the device is configured to use, in the digital filtering, the function:

a_out=a_in/√

{square root over ([1+(f/f₀)²)}],

where f is the frequency and f₀ is a suitably selected boundary frequency.

18. The device according to claim 16, wherein the device is configured to

determine the step cycle-specific characteristic maximum accelerations a_max as maxima for each step cycle of the signals a_in from the acceleration sensor filtered with digital weighting, and

determine the step cycle-specific characteristic minimum accelerations a_min as minima for each step cycle of the signals a_in from the acceleration sensor filtered with digital weighting.

19. The device according to claim 16, wherein the device is configured to

determine the step cycle-specific characteristic maximum accelerations a_max as mean values for each step cycle of the signals a_in from the acceleration sensor filtered with digital weighting over times selected during the positive half-cycle;

and

determine the step cycle-specific characteristic minimum accelerations a_min as mean values for each step cycle of the signals a_in from the acceleration sensor filtered with digital weighting over times selected during the negative half-cycle.

20. The device according to claim 18, wherein the device is configured to use, in the digital weighted filtering, the function:

a_out(n)=(1−

k)*a_out(n−

1)+a_in*k,

where n indicates the n;

th sample and k is the weighting factor.

21. The device according to claim 16, wherein the device is configured to calculate the speed v based on the step cycle-specific characteristic maximum accelerations a_max of the vertical acceleration as follows:

22. The device according to claim 16, wherein the device is configured to calculate the speed v based on the step cycle-specific characteristic minimum accelerations a_min of the vertical acceleration as follows:

v≈

k·

√

{square root over (|a_min|)}.

23. The device according to claim 16, wherein the device is configured, in calculating the quantities describing the progress of the moving person, to determine the time T_step used up for one step as a time interval between two equivalent points, such as a maximum, a minimum, or a point of exceeding or falling below a certain value, on an acceleration graph derived from the measured values of the vertical acceleration.

24. The device according to claim 23, wherein the device is configured to calculate the step length s_step using the formula:

s_step=v*T_step.

25. The device according to claim 23, wherein the device is configured to calculate the step rate f_step using the formula:

f_step=1/T_step.

26. The device according to claim 23, wherein the device is configured to calculate the step count n based on a number n of equivalent points, such as a maximum, a minimum, or a point of exceeding or falling below a certain value, on the acceleration graph given by the measured values of vertical acceleration.

27. The device according to claim 23, wherein the device is configured to calculate the distance covered s as a sum of the step lengths:

28. The device according to claim 16, wherein the device is configured to distinguish between ways of progress, selected from one of walking, running, and skiing, based on acceleration maximum and minimum, the step cycle-specific characteristic maximum and minimum acceleration values a_max and a_min and/or the step rate.

29. The device according to claim 28, wherein the device is configured to make an individual calibration for each way of progress, selected from one of running, walking, pole walking, or cross-country skiing.

30. The device according to claim 16, wherein the device is configured for use in step-by-step navigation.

31. The device according to claim 30, wherein the device is configured to cooperate with an altimeter, satellite navigation devices, and/or a magnetometer.

32. The device according to claim 30, wherein the device is configured to receive and/or utilize map database data and/or terrain inclination data.

33. A device configured to be positioned at a middle of a body of a moving person, wherein the device comprises a device according to claim 16 for measuring the progress of the moving person.

34. The device according to claim 33, wherein the device configured to be positioned at the middle of the body of the moving person can be configured to a piece of clothing, a piece of headwear, the neck, a pocket, or a belt of the moving person.

35. A display unit for a moving person, wherein the display unit for the moving person is configured to cooperate with a device according to claim 16 measuring the progress of a moving person.

36. A system for measuring a progress of a moving person, wherein the system comprises a device according to claim 16 for measuring the progress of the moving person, and a display unit for the moving person that is configured to cooperate with the device.

37. The system according to claim 36, wherein the device for measuring the progress of the moving person and the display unit for the moving person are integrated in one device.