Control circuit for sensor array and related methods

• US 20070234825A1
• Filed: 03/29/2006
• Published: 10/11/2007
• Est. Priority Date: 03/29/2006
• Status: Active Grant

• Current Assignee: Tekscan, Inc.
• Original Assignee: Tekscan, Inc.
• Inventors: Lefko, Janet, Dubinsky, Boris, Loomis, Gary
• Granted Patent: US 7,591,165 B2
• Time in Patent Office: Days
• US Class Current: 73/862
• CPC Class Codes: G01L 1/205 using distributed sensing elements
• CPC Class Codes: G01L 25/00 Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
• CPC Class Codes: G01L 27/002 Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination

Abstract

A control circuit for scanning a pressure or force responsive sensor array is disclosed. Pressure or force sensors formed of an array of pressure or force responsive sensor elements can be used to acquire pressure or force measurements in response to an applied load. The control circuit can sample signals from the sensor elements to detect the pressure or force at one or more sensor elements of the sensor array. The circuit herein may provide for relatively faster scan rates. A user may define a subset or subsets of sensor elements of the sensor array to be scanned. Various methods and related circuitry for adjusting for sensor characteristics are also disclosed.

Claims

1. A method of calibrating a sensor array of pressure or force responsive sensor elements, each of the sensor elements being connected by one of one or more first electrodes and one of one or more second electrodes, the sensor elements having signals generated therethrough, the signals being characteristic of a pressure or force applied to the sensor array, the method comprising:

(A) selecting one of the sensor elements of the sensor array;

(B) providing a drive voltage on a first electrode so as to drive the selected sensor element; and

(C) determining a path resistance associated with the selected sensor element, wherein the path resistance associated with the selected sensor element comprises at least a resistance of the first electrode and a second electrode that connect to the selected sensor element.

2. The method of claim 1, wherein (C) comprises:

varying the drive voltage provided to the first electrode to drive the selected sensor element until a signal indicative of a voltage outputted by the second electrode of the selected sensor element attains a desired value.

3. The method of claim 1, wherein (C) comprises:

obtaining a current flowing through the path resistance associated with the selected sensor element; and

determining the path resistance associated with the selected sensor element at least partially based on the obtained current.

4. The method of claim 3, wherein (C) further comprises obtaining a voltage drop across the path resistance associated with the selected sensor element, and determining the path resistance associated with the selected sensor element further based on tie voltage drop across the path resistance associated with the selected sensor element.

5. The method of claim 1, wherein (A), (B), and (C) are performed for some or all of the sensor elements of the sensor array.

6. A method of scanning a sensor array of pressure or force responsive sensor elements, each of the sensor elements being connected by one of one or more first electrodes and one of one or more second electrodes, the method comprising:

(A) obtaining a path resistance of a selected sensor element, the path resistance comprising at least a resistance of a first and a second electrode that connect to the selected sensor element;

(B) obtaining a current flowing through the path resistance associated with the selected sensor element;

(C) determining a voltage drop across the path resistance of the selected sensor element at least partially based on the path resistance obtained in (A) and the current obtained in (B); and

(D) modifying a drive voltage applied to the first electrode that connects to the selected sensor element at least partially based on the voltage drop obtained in (C).

7. The method of claim 6, wherein (C) comprises calculating the voltage drop across the path resistance of the selected sensor element by multiplying the path resistance obtained in (A) and the current obtained in (B).

8. The method of claim 6, wherein (D) comprises adding the voltage drop determined in (C) to the drive voltage.

9. The method of claim 6, wherein (A) comprises obtaining the path resistance of the selected sensor element from calibration data.

10. The method of claim 6, wherein (A), (B), (C), and (D) are performed for some or all of the sensor elements of the sensor array.

11. A method of automatically adjusting gain when scanning an array of pressure or force responsive sensor elements, the method comprising:

(A) detecting received signals corresponding to one or more sensor elements being scanned;

(B) determining a signal strength value at least partially based on at least some of the received signals corresponding to the one or more sensor elements being scanned; and

(C) adjusting a gain applied to at least some of the received signals based at least partially on the signal strength value.

12. The method of claim 11, wherein the signal strength value comprises a count of a number of the received signals corresponding to the one or more sensor elements being scanned that are greater than a threshold signal value.

13. The method of claim 11, wherein (C) comprises decreasing the gain applied to at least some of the received signals as a result of the signal strength value being greater than an upper limit.

14. The method of claim 11, wherein (C) comprises increasing the gain applied to at least some of the received signals as a result of the signal strength value being less than a lower limit.

15. The method of claim 11, wherein the signal strength value comprises an average received signal of the received signals corresponding to the one or more sensor elements being scanned.

16. A method of calibrating a sensitivity of a sensor array of pressure or force responsive sensor elements, each of the sensor elements being connected by one of one or more first electrodes and one of one or more second electrodes, the sensor elements having signals generated therethrough, the signals being characteristic of a pressure or force applied to the sensor array, the one or more second electrodes having received signals thereon associated with the sensor elements, the received signals being modified by a gain value, the method comprising:

(A) obtaining received signals associated with at least some of the sensor elements; and

(B) determining the gain value that modifies the received signals associated with the at least some of the sensor elements so that at least some of the received signals associated with the at least some of the sensor elements lie within a desired range.

17. The method of claim 16, wherein (B) comprises:

determining an average received signal of the received signals associated with the at least some of the sensor elements; and

determining the gain value that modifies the received signals associated with the at least some of the sensor elements so that the average received signal lies within a desired range.

18. The method of claim 17, wherein the desired range comprises a saturation point of the average received signal.

19. The method of claim 16, wherein the desired range comprises a saturation point of the at least some of the received signals.

20. The method of claim 16, wherein the determined gain value is stored as calibration data associated with the sensor array.

21. A method of adjusting a sensitivity of an array of pressure or force responsive sensor elements, each of the sensor elements being connected by one of one or more first electrodes and one of one or more second electrodes, the sensor elements having signals generated therethrough, the signals being characteristic of a pressure or force applied to the sensor array, the one or more second electrodes having received signals thereon associated with the sensor elements, the method comprising:

(A) obtaining a gain value associated with the desired sensitivity of the sensor elements; and

(B) modifying the received signals at least partially based on the gain value associated with the desired sensitivity.

22. The method of claim 21, wherein (A) comprises obtaining the gain value associated with the desired sensitivity from calibration data associated with the sensor array.

23. The method of claim 22, wherein the calibration data depends on an applied pressure or force.