Biomimetic tactile sensor

• US 7,658,119 B2
• Filed: 03/28/2007
• Issued: 02/09/2010
• Est. Priority Date: 03/28/2006
• Status: Active Grant

• Current Assignee: University of Southern California
• Original Assignee: University of Southern California
• Inventors: Johansson, Roland, Loeb, Gerald E.
• Primary Examiner(s): Caputo; Lisa M
• Assistant Examiner(s): DUNLAP, JONATHAN M
• Application Number:
  US11/692,718
• Publication Number:
  US 20070227267A1
• Time in Patent Office: 1,049 Days
• Field of Search: 738/620.46, 738/626.8, 901/46, 901/39, 901/36, 901/33, 623/24, 294/99.1, 345173-174, 345/156
• US Class Current: 73/862.046
• CPC Class Codes: B25J 13/084 Tactile sensors in general G01L5/16, G01L5/22
• CPC Class Codes: G01D 5/1655 more than one point of contact or actuation on one or more tracks
• CPC Class Codes: G01D 5/2417 by varying separation
• CPC Class Codes: G01L 5/228 using tactile array force sensors

Abstract

Disclosed is a tactile sensory system consisting of set of sensors that work by measuring impedance among plurality of electrodes. The electrodes are deployed on a substantially rigid structure that is protected form the direct contact with external objects by overlying deformable structures. These mechanical structures have similarities to the biological relationships among the distal phalanx, overlying finger pulp and covering skin and nail. Signal information is extracted form these sensors that is related to canonical physical representations used to describe stimuli to be sensed.

Claims

1. A biomimetic tactile sensor for providing an electrical indication of contact comprising:

a substantially rigid inner core having an outer surface and a plurality of electrodes on and distributed across at least a portion of the outer surface;

a deformable layer surrounding the electrodes and at least a substantial portion of the substantially-rigid inner core, the deformable layer having an inner and an outer surface;

texturing on the inner surface of the deformable layer positioned substantially opposed to at least one of the electrodes on the outer surface of the substantially-rigid inner core;

a volume of deformable material enclosed between the core and the deformable layer inner surface made of a volume-conductive liquid; and

a detection system configured to detect changes in the electrical resistance of the volume-conductive liquid between at least some of the electrodes on the outer surface of the substantially-rigid inner core caused by force exerted on the deformable layer outer surface,

wherein the texturing is configured such that it causes the electrical resistance at the opposing electrode to continue to increase in response to continued increases in the contact force that is applied to the outer surface of the deformable layer after the contact force reaches a level that causes the deformable layer to come in contact with the opposing electrode.

2. The biomimetic tactile sensor of claim 1 wherein the deformable layer is formed by dip-coating.

3. The biomimetic tactile sensor of claim 1 wherein the deformable material is injected through a channel into the space between the inner surface of the deformable layer and the core.

4. The biomimetic tactile sensor of claim 1 further including a pressure transducer located within the core to monitor the pressure of the space occupied by the deformable material.

5. The biomimetic tactile sensor of claim 4 wherein the outer surface of the deformable layer is textured and wherein the pressure transducer is configured to detect small, high frequency fluctuations in the pressure caused by sliding the textured outer surface over a textured object.

6. A biomimetic tactile sensor comprising:

a substantially rigid inner core having an outer surface that is convexly curved;

a plurality of electrodes arranged in a two-dimensional array on least a portion of the outer surface of the substantially-rigid inner core, each dimension have at least two electrodes;

a deformable layer surrounding the electrodes and at least a substantial portion of the substantially-rigid inner core, the deformable layer having an inner and an outer surface;

a volume-conductive liquid enclosed between the inner surface of the deformable layer and at least a portion of the outer surface of the substantially-rigid inner core and in electrical contact with the electrodes; and

detection circuitry coupled to the electrodes and configured to detect changes in the electrical impedance of the volume-conductive liquid between at least two of the electrodes within the two-dimensional array and to interpret such changes under certain circumstances as being indicative of a shear force that is applied to the deformable layer.

7. The biomimetic tactile sensor of claim 6 wherein the deformable layer is formed by dip-coating.

8. The biomimetic tactile sensor of claim 6 further including a pressure transducer located within the core to monitor the pressure of the space occupied by the volume-conductive liquid.

9. The biomimetic tactile sensor of claim 8 wherein the outer surface of the deformable layer is textured and wherein the pressure transducer is configured to detect small, high frequency fluctuations in the pressure caused by sliding the textured outer surface over a textured object.

10. The biomimetic tactile sensor of claim 9 wherein the detection circuitry is configured to detect the center of the force that is exerted on the outer surface of the deformable layer.

11. The biomimetic tactile sensor of claim 9 wherein the detection circuitry is configured to detect the radius of curvature in connection with contact between the outer surface of the deformable layer and an object.

12. The biomimetic tactile sensor of claim 6 wherein the volume-conductive liquid is injected through a channel into the space between the inner surface of the deformable layer and the core.