FABRIC-BASED PRESSURE SENSOR ARRAYS AND METHODS FOR DATA ANALYSIS

• US 20120323501A1
• Filed: 05/18/2012
• Published: 12/20/2012
• Est. Priority Date: 05/20/2011
• Status: Active Grant

• Current Assignee: Abena Holding A/S (Abena A/S), Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Sarrafzadeh, Majid, Xu, Wenyao, Huang, Ming-Chun, Raut, Nitin, Yadegar, Behrooz
• Granted Patent: US 9,271,665 B2
• Time in Patent Office: Days
• US Class Current: 702/41
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/4561 Evaluating static posture, e.g. undesirable back curvature A61B5/1116 takes precedence
• CPC Class Codes: A61B 5/4806 Sleep evaluation A61B5/4821 takes precedence; devices for inducing sleep A61M21/02
• CPC Class Codes: A61B 5/6804 Garments; Clothes
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 1/205 using distributed sensing elements

Abstract

A fabric-based pressure sensor array includes: (1) a first layer including M elongated conductive strips coated thereon; (2) a second layer including N elongated conductive strips coated thereon, the M elongated conductive strips extending crosswise relative to the N elongated conductive strips to define M×N intersections; and (3) a unitary textile sheet extending between the first layer and the second layer so as to overlap the M×N intersections, the textile sheet having a variable resistivity in response to applied pressure so as to define M×N pressure sensors at locations corresponding to the M×N intersections.

Claims

1. A fabric-based pressure sensor array, comprising:

a first layer including M elongated conductive strips coated thereon;

a second layer including N elongated conductive strips coated thereon, the M elongated conductive strips extending crosswise relative to the N elongated conductive strips to define M×

N intersections; and

a unitary textile sheet extending between the first layer and the second layer so as to overlap the M×

N intersections, the textile sheet having a variable resistivity in response to applied pressure so as to define M×

N pressure sensors at locations corresponding to the M×

N intersections.

2. The fabric-based pressure sensor array of claim 1, wherein the first layer corresponds to a top textile sheet that is coated with an electrically conductive material to form the M elongated conductive strips, and M is greater than 1.

3. The fabric-based pressure sensor array of claim 1, wherein the second layer corresponds to a bottom textile sheet that is coated with an electrically conductive material to form the N elongated conductive strips, and N is greater than 1.

4. The fabric-based pressure sensor array of claim 1, wherein the textile sheet includes fibers coated with an electrically conductive material.

5. The fabric-based pressure sensor array of claim 4, wherein the fibers are coated with an electrically conductive polymer.

6. The fabric-based pressure sensor array of claim 1, further comprising a first isolation layer disposed between the first layer and the textile sheet.

7. The fabric-based pressure sensor array of claim 6, further comprising a second isolation layer disposed between the textile sheet and the second layer.

8. A fabric-based pressure sensor array, comprising:

a textile sheet having a first surface and a second surface, and including M elongated conductive strips coated on the first surface and N elongated conductive strips coated on the second surface,

wherein the M elongated conductive strips extend crosswise relative to the N elongated conductive strips to define M×

N intersections, and the textile sheet has a variable resistivity in response to applied pressure so as to define M×

N pressure sensors at locations corresponding to the M×

N intersections.

9. The fabric-based pressure sensor array of claim 8, wherein the textile sheet includes fibers coated with an electrically conductive material.

10. The fabric-based pressure sensor array of claim 9, wherein the fibers are coated with an electrically conductive polymer.

11. A fabric-based pressure sensor array, comprising:

a textile sheet having a first surface and a second surface;

a plurality of contact pads disposed adjacent to the first surface of the textile sheet; and

a ground contact pad disposed adjacent to the second surface of the textile sheet and sized so as to at least partially overlap each of the plurality of contact pads to define a plurality of overlapping regions,

wherein the textile sheet exhibits piezoresistivity so as to define a plurality of pressure sensors at locations corresponding to the plurality of overlapping regions.

12. The fabric-based pressure sensor array of claim 11, wherein the ground contact pad provides a common ground connection for the plurality of pressure sensors.

13. The fabric-based pressure sensor array of claim 11, wherein the plurality of contact pads are coated on the first surface of the textile sheet.

14. The fabric-based pressure sensor array of claim 11, further comprising a first layer disposed adjacent to the first surface of the textile sheet, and the plurality of contact pads are coated on the first layer.

15. The fabric-based pressure sensor array of claim 11, wherein the ground contact pad is coated on the second surface of the textile sheet.

16. The fabric-based pressure sensor array of claim 11, further comprising a second layer disposed adjacent to the second surface of the textile sheet, and the ground contact pad is coated on the second layer.

17. The fabric-based pressure sensor array of claim 11, wherein the ground contact pad is sized to provide flexibility to the fabric-based pressure sensor array.

18. A non-transitory computer-readable storage medium, comprising executable instructions to:

receive a pressure distribution of an object as applied against an array of pressure sensors;

select a pressure value from the pressure distribution as an outlier pressure value;

adjust the outlier pressure value according to neighboring pressure values in the pressure distribution to derive an updated pressure distribution; and

based on the updated pressure distribution, derive a posture of the object as applied against the array of pressure sensors.

19. The non-transitory computer-readable storage medium of claim 18, wherein the executable instructions to select the outlier pressure value include executable instructions to identify the outlier pressure value as falling outside of a statistical threshold range for the pressure distribution.

20. The non-transitory computer-readable storage medium of claim 18, wherein the executable instructions to adjust the outlier pressure value include executable instructions to derive an updated statistical threshold range for the updated pressure distribution.

21. The non-transitory computer-readable storage medium of claim 20, further comprising executable instructions to:

select a pressure value from the updated pressure distribution as an outlier pressure value; and

adjust the outlier pressure value in the updated pressure distribution according to neighboring pressure values in the updated pressure distribution to obtain a further updated pressure distribution.

22. A non-transitory computer-readable storage medium, comprising executable instructions to:

receive a pressure map of a human subject as applied against an array of pressure sensors, at least a subset of the array of pressure sensors being coupled via crosstalk;

apply a decoupling transformation to the pressure map to derive an updated pressure map in which the crosstalk is at least partially reduced; and

based on the updated pressure map, derive a posture of the human subject as applied against the array of pressure sensors.

23. The non-transitory computer-readable storage medium of claim 22, wherein the decoupling transformation corresponds to an inverse of a matrix transformation relating forces applied on the array of pressure sensors and outputs of the array of pressure sensors.

24. A system for posture recognition, comprising:

a processing unit; and

a memory connected to the processing unit and including executable instructions to;

receive data corresponding to a two-dimensional pressure distribution of an object as applied against a sensor sheet;

convert the data into a one-dimensional pressure sequence; and

based on the pressure sequence, infer a posture of the object as applied against the sensor sheet.

25. The system of claim 24, wherein the executable instructions to convert the data into the pressure sequence include executable instructions to:

derive an outline curve in the two-dimensional pressure distribution; and

derive distances between multiple points on the outline curve and a reference point in the two-dimensional pressure distribution.

26. The system of claim 25, wherein the executable instructions to infer the posture of the object include executable instructions to process the pressure sequence according to a machine learning procedure.

27. The system of claim 24, wherein the executable instructions to infer the posture of the object include executable instructions to match the pressure sequence with a set of reference pressure sequences according to Dynamic Time Warping.