Force measuring device and method

• US 6,673,026 B2
• Filed: 03/27/2001
• Issued: 01/06/2004
• Est. Priority Date: 03/27/2000
• Status: Expired due to Fees

• Current Assignee: San Diego State University Foundation
• Original Assignee: San Diego State University Foundation
• Inventors: Agraz, Jose L., Pozos, Robert S.
• Primary Examiner(s): Hindenburg, Max F.
• Assistant Examiner(s): WINGOOD, PAMELA LYNN
• Application Number:
  US09/819,183
• Publication Number:
  US 20010049482A1
• Time in Patent Office: 1,015 Days
• Field of Search: 600/300, 600/301, 600/587, 600/588, 600/589, 600/590, 600/591, 600/592, 600/593, 600/594, 600/595, 434/247, 482/2-4, 482/51-111, 463/1-47
• US Class Current: 600/587
• CPC Class Codes: A61B 2560/0228 using calibration standards
• CPC Class Codes: A61B 2560/0406 specially shaped apparatus housings
• CPC Class Codes: A61B 5/1107 Measuring contraction of parts of the body, e.g. organ, muscle apparatus for measuring work or force in general G01L
• CPC Class Codes: A61B 5/225 of the fingers, e.g. by monitoring hand-grip force
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6897 Computer input devices, e.g. mice or keyboards
• CPC Class Codes: G06F 3/0219 Special purpose keyboards
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device
• CPC Class Codes: H01H 2217/044 Repetitive strain injury [RSI] considerations

Abstract

The present invention relates to a device and method for measuring force, primarily due to fatigue. In one embodiment, a finger fatigue measuring system is provided which measures the force output from fingers while the fingers are repetitively generating forces as they strike a keyboard. Force profiles of the fingers are generated from the measurements and evaluated for fatigue. The system can be used clinically to evaluate patients, to ascertain the effectiveness of clinical intervention, pre-employment screening, to assist in minimizing the incidence of repetitive stress injuries at the keyboard, mouse, joystick, and to monitor effectiveness of various finger strengthening systems. The system can also be used in a variety of different applications adapted for measuring forces produced during performance of repetitive motions.

Claims

1. A method for measuring force produced by at least one body part of a subject performing repetitive motions, said motions including applying force to a force sensing member connected to a force measuring apparatus, said method comprising the steps of:

a) measuring a signal as a function of force produced by the body part during performance of the repetitive motions;

b) measuring a signal as a function of force effects on the force sensing member during performance of the repetitive motions;

c) converting the signal from step a) to a force production profile; and

d) converting the signal from step b) to a force effect profile.

2. The method according to claim 1, wherein step a) further comprises generating measurable signals in proportion to the forces.

3. The method according to claim 2, wherein step c) further comprises converting the signal into a sequence of discrete force production data representative of the forces generated by the body part.

4. The method according to claim 1, further comprising the step of measuring EMG signals from one or more muscles of the subject.

5. The method according to claim 4, further comprising the step evaluating the EMG signals for fatigue.

6. The method according to claim 1, wherein the body part is a finger, said finger being part of a hand, and wherein the repetitive motions are repeatedly pressing keys with fingers.

7. The method according to claim 6, wherein step a) further comprises generating signals in proportion to the forces produced by the fingers pressing the keys.

8. The method according to claim 7, wherein step c) further comprises converting the signals into discrete force production data representative of the forces generated by the finger.

9. The method according to claim 6, wherein the hand further comprises a hand base.

10. The method according to claim 8, further comprising the step of measuring a baseline force output for each of the fingers.

11. The method of claim 10, further comprising the step of normalizing the discrete force production data with the baseline force output to produce normalized force production data representative of the forces generated by the fingers.

12. The method according to claim 11, further comprising the step of calculating a rate of amplitude change from the normalized force-production data.

13. The method according to claim 12, further comprising the step of converting the rate of amplitude change into a value representative of fatigue.

14. The method according to claim 9, further comprising the step of measuring signal characteristic of force produced by the hand base as the keys are repeatedly pressed with the fingers.

15. The method according to claim 14, wherein step a) further comprises generating a first set of signals in proportion to the forces produced by the hand base and a second set of signals in proportion to the forces produced by the fingers.

16. The method according to claim 15, wherein step d) further comprises converting the first set of signals into a first set of discrete force data representative of the forces generated by the hand base and converting the second set of signals into a second set of discrete force data representative of the forces generated by the fingers.

17. The method according to claim 16, further comprising the steps of calculating a first rate of amplitude change from the first set of discrete force data and a second rate of amplitude change from the second set of force data.

18. The method according to claim 17, further comprising the step of converting the first rate of amplitude change, the second rate of amplitude change or the relationship between the first rate of amplitude change and the second rate of amplitude change into a value representative of fatigue.

19. The method according to claim 1, wherein step d) further comprises determining a force effect event frequency from the force effect profile.

20. A force sensing member adapted for use in a force measuring apparatus for measuring force produced by at least one body part of a person performing repetitive motions, said force sensing member comprising:

a) a force sensor functionally associated with the force sensing member that generates a signal characteristic of force produced by the body part and transmitted to the force sensing member during performance of the repetitive motions; and

b) a switch sensor functionally associated with the force sensing member that generates a signal when depression and release of the force sensing member occurs during performance of the repetitive motions.

21. A force measuring apparatus comprising at least one force sensing member according to claim 20 and a housing.

22. A force measuring system comprising the force measuring apparatus of claim 21 and a computer, wherein said computer further comprises a processor, and wherein said processor converts:

the signal from the force sensor to a force production profile; and

the signal from the switch sensor into a force effect profile.

23. The force measuring apparatus according to claim 21 further comprising a keyboard having a plurality of keys, wherein the force sensor and switch sensor are functionally associated with at least one key.

24. The force measuring apparatus according to claim 21 further comprising a computer mouse having a mouse button, wherein the force sensor and switch sensor are functionally associated with the mouse button.

25. The force measuring apparatus according to claim 21 further comprising a joystick having a firing button, wherein the force sensor and switch sensor are functionally associated with the firing button.

26. The force measuring system according to claim 22, wherein said computer further comprises an output device for displaying the force production profile and the force effect profile.

27. A computer game system adapted for measuring force produced by at least one body part of a person performing repetitive motion while playing the computer game, wherein said system comprises a force sensing member further comprising:

a) a force sensor functionally associated with the force sensing member that generates a signal as a function of force produced by the body part and transmitted to the force sensing member during play of the game; and

b) a switch sensor functionally associated with the force sensing member that generates a signal when depression and release of the force sensing member occurs during play of the game.

28. The computer game system according to claim 27 further comprising a processor, wherein said processor is programmed to

a) receive signal from the force sensor and convert the signal to a force production profile; and

b) receive signal from the switch sensor and convert the signal to a force effect profile.