Biomimetic Tactile Sensor for Control of Grip

• US 20090133508A1
• Filed: 05/16/2008
• Published: 05/28/2009
• Est. Priority Date: 05/18/2007
• Status: Active Grant

• Current Assignee: University of Southern California
• Original Assignee: University of Southern California
• Inventors: Santos, Veronica J., Loeb, Gerald E., Popovic, Djordje, Wettels, Nicholas, Johansson, Roland S.
• Granted Patent: US 7,878,075 B2
• Time in Patent Office: Days
• US Class Current: 73/862.46
• CPC Class Codes: B25J 13/084 Tactile sensors in general G01L5/16, G01L5/22
• CPC Class Codes: G01D 5/2417 by varying separation
• CPC Class Codes: G01L 1/205 using distributed sensing elements
• CPC Class Codes: G01L 5/228 using tactile array force sensors

Abstract

Disclosed is a robust tactile sensor array that mimics the human fingertip and its touch receptors. The mechanical components are similar to a fingertip, with a rigid core surrounded by a weakly conductive fluid contained within an elastomeric skin. It uses the deformable properties of the finger pad as part of the transduction process. Multiple electrodes are mounted on the surface of the rigid core and connected to impedance measuring circuitry within the core. External forces deform the fluid path around the electrodes, resulting in a distributed pattern of impedance changes containing information about those forces and the objects that applied them. Strategies for extracting features related to the mechanical inputs and using this information for reflexive grip control.

Claims

1. ) A biomimetic tactile sensor for detecting a wide dynamic range of output signals comprising:

a) a substantially rigid core having 20-100 sensing electrodes distributed along the surface of the substantially rigid core, wherein each of the electrodes is configured to sense contact information relating to contact between the electrode and another object independent of the contact information sensed by the other electrodes;

b) at least one deformable skin-like layer attached to the core; and

c) detection circuitry mounted within the core and electrically coupled to the electrodes and configured to detect contact information sensed by each of the electrodes at a resolution of 12 or more bits per sample data, wherein each sample data is one contact information detected by each of the electrodes.

2. ) The biomimetic tactile sensor of claim 1, wherein each of the electrodes comprises material selected from inert metals.

3. ) The biomimetic tactile sensor of claim 1, wherein the detection circuitry is further configured to apply alternating current to each of the electrodes at a frequency in the range 5-100 KHz.

4. ) The biomimetic tactile sensor of claim 1, wherein the detection circuitry is configured to sample the contact information from each of the electrodes at 100 or more times per second.

5. ) The biomimetic tactile sensor of claim 1, wherein the detection circuitry further comprises an analog to digital converter (ADC) configured to receive a cycling clock signal, wherein the ADC is configured to generate multi-bit binary samples of the contact information and to generate each bit during a single clock cycle.

6. ) The biomimetic tactile sensor of claim 5, wherein the detection circuitry is configured to receive the clock signal from a circuit that is external to the core.

8. ) The biomimetic tactile sensor of claim 1, wherein the detecting circuitry is configured to provide signal conditioning, digitizing, serializing and synchronizing.

7. ) The biomimetic tactile sensor of claim 7, wherein the clock signal is a substantially-square-wave signal.

9. ) A biomimetic tactile sensor that substantially mimics a human fingertip and its distributed touch receptors comprising:

a) a substantially rigid core;

b) a plurality of electrodes distributed along the surface of the core, wherein each of the electrodes is configured to sense contact information relating to contact between the electrode and another object independent of the contact information sensed by the other electrodes;

c) at least one deformable skin-like layer attached to the core having an inner and an outer surface, wherein at least one of the surfaces is textured;

d) deformable material between the core and the inner surface of the at least one deformable layer; and

e) detection circuitry mounted within the core and electrically coupled to the plurality of the electrodes and configured to detect contact information sensed by each of the electrodes.

10. ) The biomimetic tactile sensor of claim 13, wherein the texture of the surface comprises fine and random patterns.

11. ) The biomimetic tactile sensor of claim 9, wherein the texture of the surface is rough and/or spongy.

12. ) The biomimetic tactile sensor of claim 9, wherein the textured surface comprises one or more protruding elements.

13. ) The biomimetic tactile sensor of claim 9, further comprising a capillary tube configured to hold and introduce the deformable material between the core and the inner surface of the deformable layer.

14. ) The biomimetic tactile sensor of claim 9, further comprising at least one sensor configured to measure pressure or temperature of the deformable material.

15. ) A fingertip-like biomimetic tactile sensor for delivering an electrical indication of contact to control a grip comprising:

a) a substantially rigid core having a curved surface;

b) a plurality of electrodes distributed along the curved surface of the core;

c) at least one deformable layer having an inner and an outer surface;

d) deformable material enclosed between the core and the inner surface of the at least one deformable layer; and

e) detection circuitry configured to detect contact information from at least one of the plurality of the electrodes and to generate an electrical indication of the contact information for controlling a grip.

16. ) The biomimetic tactile sensor of claim 15, wherein the detection circuitry is configured to provide contact information that is related to any one of an object'"'"'s size, shape, mass or weight distribution or coefficient of friction between the object and the deformable layer outer surface.

17. ) The biomimetic tactile sensor of claim 16, further comprising a grip configured to receive the electrical indication of the contact information and wherein the grip is adjusted based on the detected contact information.

18. ) The biomimetic tactile sensor of claim 17, wherein the grip is configured to make an adjustment mediated reflexively by either a person'"'"'s spinal cord or brain.

19. ) The biomimetic tactile sensor of claim 15, further comprising a neural networks trained controller, and wherein the detection circuitry is further configured to provide a signal usable to control the grip based on commands received from the neural networks trained controller.

20. ) The biomimetic tactile sensor of claim 19, wherein the trained controller produces patterns of grip adjustments that mimic reflexive responses of a human subject.