SENSOR EQUILIBRATION AND CALIBRATION SYSTEM AND METHOD

• US 20060021418A1
• Filed: 07/27/2004
• Published: 02/02/2006
• Est. Priority Date: 07/27/2004
• Status: Active Grant

• Current Assignee: Tekscan, Inc.
• Original Assignee: Tekscan, Inc.
• Inventors: George, Christopher, Malacaria, Charles
• Granted Patent: US 6,993,954 B1
• Time in Patent Office: Days
• US Class Current: 73/1.150
• CPC Class Codes: G01L 25/00 Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency

Abstract

A system and method for equilibrating and calibrating a pressure or force sensor is provided. The system includes a flexible bag arranged to receive the sensor, and a vacuum source, connectable with the flexible bag, adapted to reduce the pressure within the flexible bag. By reducing the pressure within the flexible bag, such that the pressure inside of the bag is less than the pressure outside of the bag, the resultant uniform pressure acting on the sensor is used to calibrate and equilibrate the sensor. The system may include a porous material in the flexible bag to facilitate the evacuation of air from within the flexible bag as the pressure is reduced. The system may also include an opening, such that when the sensor is placed in the bag, a portion of the sensor extends outside of the bag to communicate with a controller. The opening may be provided either on the flexible bag, or on a clamp attached to the flexible bag. The system and method for calibrating and equilibrating a sensor may be employed to correct for sensor variations and/or to correlate sensor output to force or pressure.

Claims

1. A system for calibrating and/or equilibrating a force or pressure sensor, comprising:

a flexible bag, forming a chamber within, the flexible bag constructed and arranged to receive the sensor;

a vacuum source, connectable to the chamber, adapted to reduce the pressure in the chamber; and

a controller constructed and arranged to communicate with the sensor placed within the chamber, wherein the controller is adapted to receive at least one signal from the sensor, representative of a force or pressure applied to the sensor upon application of external pressure acting on the sensor when the pressure within the chamber is reduced by the vacuum source so as to calibrate and/or equilibrate the sensor.

2. The system of claim 1, further comprising a porous material disposed within the chamber, the porous material constructed and arranged to facilitate evacuation of air from within the chamber as the pressure within the chamber is reduced.

3. The system of claim 2, wherein the porous material is constructed and arranged to extend at least partially around the outer perimeter of the sensor.

4. The system of claim 2, wherein the porous material comprises at least one of foam, felt or fabric.

5. The system of claim 1, further comprising a base disposed within the chamber, the base constructed and arranged to support the sensor when the sensor is within the chamber.

6. The system of claim 5, further comprising a porous material supported by the base, wherein the porous material is constructed and arranged to facilitate evacuation of air from within the chamber as the pressure within the chamber is reduced.

7. The system of claim 1, further comprising a clamp cooperating with the flexible bag.

8. The system of claim 7, wherein the clamp comprises an opening therethrough, such that when the sensor, having an electronic lead adapted to be coupled to the controller, is placed within the chamber, at least a portion of the electronic lead extends out of the chamber through the opening in the clamp, when the clamp is in a closed position.

9. The system of claim 1, in combination with the sensor, wherein the sensor comprises:

at least one substrate layer; and

a plurality of individual sensor elements operatively arranged with respect to the substrate layer.

10. The combination of claim 9, wherein the sensor further comprises at least one electronic lead adapted to be coupled to the controller.

11. The system of claim 1, wherein the flexible bag comprises at least two layers of a conformable non-porous material, wherein at least a portion of the two layers are sealed together.

12. The system of claim 11, wherein the at least a portion of the two layers are welded together.

13. The system of claim 1, wherein the flexible bag further comprises at least one port adapted to communicate with the vacuum source.

14. The system of claim 13, wherein the vacuum source comprises a pump and conduit adapted to connect to the at least one port.

15. The system of claim 11, wherein the two layers of non-porous material are formed from one folded-over piece of conformable non-porous material.

16. A method of calibrating and/or equilibrating a pressure or force sensor, comprising the steps of:

providing a flexible bag;

placing the sensor within the flexible bag to calibrate and/or equilibrate the sensor;

applying a first pressure within the flexible bag, wherein the first pressure is less than the pressure outside of the flexible bag;

measuring a signal from the sensor, representative of a force applied to the sensor upon application of the pressure outside of the bag acting on the sensor when the pressure within the flexible bag is reduced by the application of the first pressure, so as to calibrate and/or equilibrate the sensor under the first pressure; and

removing the sensor from the flexible bag.

17. The method of claim 16, wherein the sensor comprises at least one electronic lead, adapted to be coupled to a controller, the electronic lead constructed and arranged to transmit a signal from the sensor, representative of a force applied to the sensor, to the controller, and wherein the sensor is placed within the flexible bag such that at least a portion of the electronic lead is positioned outside of the flexible bag when the first pressure is applied within the bag.

18. The method of claim 16, further comprising the steps of:

applying a second pressure within the flexible bag, wherein the second pressure is less than the pressure outside of the flexible bag; and

measuring a signal from the sensor, representative of a force applied to the sensor upon application of the pressure outside of the bag acting on the sensor when the pressure within the flexible bag is reduced by the application of the second pressure, so as to calibrate and/or equilibrate the sensor under the second pressure.

19. The method of claim 16, wherein the sensor comprises a plurality of individual sensor elements, the method further comprising the steps of:

providing a controller constructed and arranged to communicate with the sensor, wherein the controller is adapted to receive at least one signal from the individual sensor elements representative of a force applied to the sensor elements; and

adjusting the output of at least one sensor element based upon the at least one signal from the sensor elements and the average of the signals from multiple sensor elements.

20. The method of claim 16, wherein the sensor comprises a plurality of individual sensor elements, the method further comprising the step of:

providing a controller constructed and arranged to communicate with the sensor, wherein the controller is adapted to receive at least one signal from the individual sensor elements representative of a force or pressure applied to the sensor elements; and

converting the output of at least one sensor element from a signal to a force or pressure, based upon the area of the sensor and the first applied pressure.

21. The method of claim 16, wherein the sensor comprises an electronic lead, adapted to be coupled to a controller to transmit at least one signal from the sensor to the controller, the method further comprising the step of:

providing an opening into the flexible bag such that at least a portion of the electronic lead is positioned outside of the flexible bag while calibrating and/or equilibrating the sensor.

22. The method of claim 21, further comprising the steps of:

providing a clamp positioned on a portion of the flexible bag; and

securing the clamp in a closed position after the sensor is placed at least partially within the flexible bag.

23. The method of claim 22, wherein the opening is provided on the clamp, such that at least a portion of the electronic lead is positioned outside of the flexible bag, through the opening on the clamp.

24. The method of claim 16, wherein the pressure outside of the flexible bag is atmospheric pressure.

25. The method of claim 16, wherein the first pressure is substantially a vacuum.

26. The method of claim 18, wherein the second pressure is less than atmospheric pressure but greater than the first pressure.

27. The method of claim 16, further comprising the step of:

providing a porous material disposed within the flexible bag, constructed and arranged to facilitate evacuation of air from within the flexible bag as the pressure within the flexible bag is reduced.

28. The method of claim 16, further comprising the step of:

providing a base disposed within the flexible bag, the base constructed and arranged to support the sensor when the sensor is in the flexible bag.

29. The method of claim 27, wherein the porous material is supported by a base, and wherein the porous material extends at least partially around the outer perimeter of the sensor.

30. A system for calibrating and/or equilibrating a pressure or force sensor, comprising:

a flexible bag, forming a chamber within, the flexible bag constructed and arranged to receive the sensor;

a clamp cooperating with the flexible bag, adapted to seal the chamber when the clamp is in a closed position;

a vacuum source, connectable to the chamber, adapted to reduce the pressure in the chamber; and

instructions for calibrating and/or equilibrating the sensor by placing at least a portion of the sensor into the flexible bag, and thereafter receiving at least one signal from the sensor, representative of a force or pressure applied to the sensor upon application of a pressure outside of the chamber acting on the sensor when the pressure within the chamber is reduced by the vacuum source.

31. The system of claim 30, wherein the clamp further comprises an opening therethrough, adapted to hold a portion of the sensor inside of the chamber and a portion of the sensor outside of the chamber when the clamp is in the closed position.

32. The system of claim 30, in combination with the sensor, wherein the sensor comprises:

at least one substrate layer; and

a plurality of individual sensor elements operatively arranged with respect to the substrate layer.

33. The system of claim 31, in combination with the sensor, wherein the sensor comprises:

at least one substrate layer;

a plurality of individual sensor elements operatively arranged with respect to the substrate layer; and

at least one electronic lead adapted to be coupled to a controller, to transmit at least one signal from the sensor to the controller, and wherein at least a portion of the electronic lead extends out of the flexible bag, through the opening in the clamp when the clamp is in the closed position.

34. The system of claim 30, further comprising a porous material adapted to be disposed within the chamber, the porous material constructed and arranged to facilitate evacuation of air from within the chamber as the pressure within the chamber is reduced.

35. The system of claim 30, wherein the flexible bag further comprises at least one port adapted to communicate with the vacuum source.

36. The system of claim 35, wherein the vacuum source comprises a pump and conduit adapted to connect to the at least one port.

37. A system for calibrating and/or equilibrating a pressure or force sensor, comprising:

a flexible bag, forming a chamber within, the flexible bag constructed and arranged to receive the sensor; and

a porous foam material disposed within the chamber, the porous foam material constructed and arranged such that when the sensor is placed within the chamber and the pressure within the chamber is reduced to below atmospheric pressure, the porous foam material facilitates the evacuation of a gas within the chamber.

38. The system of claim 37, further comprising a base disposed within the chamber, the base constructed and arranged to support the sensor when the sensor is within the chamber.

39. The system of claim 37, wherein the system is adapted to be rolled or folded into a smaller configuration for travel or storage.

40. The system of claim 38, wherein the porous foam material is supported by the base, and wherein the porous material is constructed and arranged to extend at least partially around the outer perimeter of the sensor.

41. The system of claim 37, further comprising a clamp positioned along an edge of the flexible bag.

42. The system of claim 41, wherein the clamp comprises an opening therethrough, such that when the sensor, having an electronic lead adapted to be coupled to a controller, is placed within the chamber, at least a portion of the electronic lead extends out of the chamber through the opening in the clamp, when the clamp is in a closed position.

43. The system of claim 37, in combination with the sensor, wherein the sensor comprises:

at least one substrate layer; and

a plurality of individual sensor elements operatively arranged with respect to the substrate layer.

44. A method of calibrating and/or equilibrating a pressure or force sensor, comprising the steps of:

providing a flexible bag;

placing a porous material into the flexible bag;

placing the sensor into the flexible bag adjacent the porous material, to calibrate and/or equilibrate the sensor;

applying a first pressure within the flexible bag, wherein the first pressure is less than the pressure outside of the bag, and wherein the porous material facilitates the evacuation of a gas within the flexible bag; and

measuring the force or pressure applied to the sensor upon application of atmospheric pressure acting on the sensor when the pressure within the bag is reduced by the application of the first pressure, so as to calibrate and/or equilibrate the sensor under the first pressure.

45. The method of claim 44, wherein the first pressure is substantially a vacuum.

46. The method of claim 44, wherein the pressure outside of the flexible bag is atmospheric pressure.

47. The method of claim 44, wherein the gas within the flexible bag is air.

48. The method of claim 44, further comprising the steps of:

applying a second pressure within the flexible bag, wherein the second pressure is less than the pressure outside of the flexible bag and greater than the first pressure, and wherein the porous material facilitates the evacuation of a gas within the flexible bag; and

measuring the force or pressure applied to the sensor upon application of the pressure outside of the bag acting on the sensor when the pressure within the bag is reduced by the application of the second pressure, so as to calibrate and/or equilibrate the sensor under the second pressure.

49. The method of claim 44, further comprising the step of:

providing a base disposed within the flexible bag, the base constructed and arranged to support the sensor when the sensor is in the flexible bag.

50. The system of claim 49, wherein the porous material is supported by the base and extends at least partially around the outer perimeter of the sensor.