Systems and methods for detecting overstriding in runners

• US 10,115,319 B2
• Filed: 03/25/2016
• Issued: 10/30/2018
• Est. Priority Date: 03/26/2015
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Walsh, Conor J., Liu, Stephanie Hsiang-Ting, Polygerinos, Panagiotis, Lieberman, Daniel E.
• Primary Examiner(s): D'Agostino, Paul A
• Application Number:
  US15/081,072
• Publication Number:
  US 20160284231A1
• Time in Patent Office: 949 Days
• Field of Search: None
• CPC Class Codes: A61B 2503/10 Athletes
• CPC Class Codes: A61B 2560/0238 Means for recording calibration data
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/112 Gait analysis
• CPC Class Codes: A61B 5/1121 Determining geometric values, e.g. centre of rotation or angular range of movement
• CPC Class Codes: A61B 5/6828 Leg
• CPC Class Codes: G09B 19/0038 Sports

Abstract

Methods and systems for detecting overstride in runners include measuring, using an inertial measurement unit affixed to a shank of a person, an acceleration and an angle of the shank during a stride, monitoring, using a microprocessor, the shank acceleration measurements to detect an acceleration profile indicative of the corresponding foot making initial contact with the ground during the stride, determining, using the microprocessor, the corresponding shank angle at initial contact from the shank angle measurements, comparing, using the microprocessor, the shank angle at initial contact to a threshold shank angle, and identifying, using the microprocessor, an overstride of the corresponding leg if the shank angle at initial contact exceeds the threshold shank angle.

Claims

1. A method for detecting overstride, the method comprising:

measuring, using an inertial measurement unit (IMU) affixed to a shank of a person, an acceleration and an angle of the shank during a stride;

monitoring, using a microprocessor, the shank acceleration measurements to detect an acceleration profile indicative of the corresponding foot making initial contact with the ground during the stride;

determining, using the microprocessor, the corresponding shank angle at initial contact from the shank angle measurements;

comparing, using the microprocessor, the shank angle at initial contact to a threshold shank angle;

identifying, using the microprocessor, an overstride of the corresponding leg if the shank angle at initial contact exceeds the threshold shank angle.

2. The method of claim 1, wherein the IMU is positioned on a front or a side of the shank.

3. The method of claim 1, wherein the IMU is affixed to the shank using an anchoring member.

4. The method of claim 3, wherein an inner surface of the anchoring member includes an anti-slip material for frictionally engaging the shank.

5. The method of claim 4, wherein the anti-slip material is patterned to allow for heat transfer and sweat wicking through corresponding portions of the anchoring member.

6. The method of claim 3, wherein the anchoring member includes at least one of a compression sleeve and a substantially longitudinally inextensible sock.

7. The method of claim 1, wherein in the step of measuring, the shank angle is measured in a sagittal plane.

8. The method of claim 1, wherein in the step of monitoring, the acceleration profile is characterized at least in part by a rapid increase in measured acceleration.

9. The method of claim 8, wherein the acceleration profile is further characterized by a relatively low acceleration magnitude leading up to the rapid increase in measured acceleration.

10. The method of claim 1, wherein in the step of comparing, the threshold shank angle corresponds with a vertical direction of the sagittal plane.

11. The method of claim 1, wherein the threshold shank angle is approximately zero degrees in a coordinate system in which zero degrees corresponds with a vertical direction of the sagittal plane, positive angles correspond with a forward direction of the stride, and negative angles correspond with a rearward direction of the stride.

12. The method of claim 11, wherein in the step of identifying, an overstride occurs if the shank angle at initial contact is positive.

13. The method of claim 1, wherein in the step of comparing, the threshold shank angle corresponds with an angle of the IMU affixed to the shank when the person is standing upright in a stationary position.

14. The method of claim 13, further including the step of determining the threshold shank angle during a calibration routine prior to the stride.

15. The method of claim 1, wherein in the step of identifying, the processor identifies an overstride of the corresponding leg utilizing measurements from only the IMU affixed to the shank of the corresponding leg.

16. The method of claim 1, wherein the step of measuring is performed for a first leg and a second leg of the person, using a first IMU affixed to a first shank of the first leg of a person, and a second IMU affixed to a second shank of the second leg of the person.

17. The method of claim 16, further including performing the steps of monitoring, determining, comparing, and identifying for the first leg and the second leg during the stride, utilizing shank angle and acceleration measurements from the first IMU and the second IMU.

18. The method of claim 17, wherein the steps of measuring, monitoring, determining, comparing, and identifying are performed for the first leg independent of the measurements from the second IMU on the second shank.

19. The method of claim 1, further comprising alerting the person when an overstride is identified.

31. The method of claim 1, wherein the threshold shank angle corresponds with an angle of the IMU affixed to the shank when the person is standing upright in a stationary position.

32. The method of claim 31, further including the step of determining the threshold shank angle during a calibration routine prior to the stride.

20. A method for detecting overstride, the method comprising:

measuring, using an inertial measurement unit (IMU) affixed to a shank of a person, an angle of the shank during a stride;

monitoring, using a microprocessor, the shank angle measurements to identify a peak angle of the shank during the stride;

comparing, using the microprocessor, the peak shank angle for the stride to a threshold shank angle; and

identifying, using the microprocessor, an overstride of the corresponding leg if the peak shank angle exceeds the threshold shank angle.

21. The method of claim 20, wherein the IMU is positioned on a front or a side of the shank.

22. The method of claim 20, wherein the IMU is affixed to the shank using an anchoring member.

23. The method of claim 22, wherein an inner surface of the anchoring member includes an anti-slip material for frictionally engaging the shank.

24. The method of claim 23, wherein the anti-slip material is patterned to allow for heat transfer and sweat wicking through corresponding portions of the anchoring member.

25. The method of claim 22, wherein the anchoring member includes at least one of a compression sleeve and a substantially longitudinally inextensible sock.

26. The method of claim 20, wherein in the step of measuring, the shank angle is measured in a sagittal plane.

27. The method of claim 26, wherein in the step of monitoring, the peak shank angle is identified as the foremost shank angle in the forward direction of the stride.

28. The method of claim 20, wherein the threshold shank angle corresponds with a vertical direction of the sagittal plane.

29. The method of claim 20, wherein the threshold shank angle is approximately zero degrees in a coordinate system in which zero degrees corresponds with a vertical direction of the sagittal plane, positive angles correspond with a forward direction of the stride, and negative angles correspond with a rearward direction of the stride.

30. The method of claim 29, wherein in the step of identifying, an overstride occurs if the peak shank angle is positive.

33. The method of claim 20, wherein in the step of identifying, the processor identifies an overstride of the corresponding leg utilizing measurements from only the IMU affixed to the shank of the corresponding leg.

34. The method of claim 20, wherein the step of measuring is performed for a first leg and a second leg of the person, using a first IMU affixed to a first shank of the first leg of a person, and a second IMU affixed to a second shank of the second leg of the person.

35. The method of claim 34, further including performing the steps of monitoring, comparing, and identifying for the first leg and the second leg during the stride, utilizing shank angle measurements from the first IMU and the second IMU.

36. The method of claim 35, wherein the steps of measuring, monitoring, comparing, and identifying are performed for the first leg independent of the measurements from the second IMU on the second shank.

37. The method of claim 20, further comprising alerting the person when an overstride is identified.