Tactile sensor using elastomeric imaging

Abstract

A tactile sensor includes a photosensing structure, a volume of elastomer capable of transmitting an image, and a reflective skin covering the volume of elastomer. The reflective skin is illuminated through the volume of elastomer by one or more light sources, and has particles that reflect light incident on the reflective skin from within the volume of elastomer. The reflective skin is geometrically altered in response to pressure applied by an entity touching the reflective skin, the geometrical alteration causing localized changes in the surface normal of the skin and associated localized changes in the amount of light reflected from the reflective skin in the direction of the photosensing structure. The photosensing structure receives a portion of the reflected light in the form of an image, the image indicating one or more features of the entity producing the pressure.

What is claimed is: 
     
       1. A tactile sensor comprising:
 a photosensing structure;   a volume of elastomer capable of transmitting an image; and   a reflective skin covering said volume of elastomer, said reflective skin being illuminated through said volume of elastomer by one or more light sources, said reflective skin having particles that non-directionally reflect light incident on the reflective skin from within the volume of elastomer, said reflective skin being geometrically altered in response to pressure applied by an entity touching said reflective skin, said geometrical alteration causing localized changes in the surface normal of said skin and associated localized changes in the amount of light reflected from said reflective skin in the direction of said photosensing structure; wherein   said photosensing structure is positioned to receive a portion of said reflected light in the form of an image, said image indicating one or more features of the entity producing said pressure.   
     
     
       2. The tactile sensor of  claim 1 , wherein said volume of elastomer comprises silicone rubber, polyurethane, plastisol, thermoplastic elastomer, natural rubber, polyisoprene, polyvinyl chloride or a mixture thereof. 
     
     
       3. The tactile sensor of  claim 1 , wherein said volume of elastomer comprises a Shore A hardness between 5 and 90. 
     
     
       4. The tactile sensor of  claim 1 , wherein the volume of elastomer is in the form of a slab. 
     
     
       5. The tactile sensor of  claim 1 , wherein said photosensing structure comprises a camera. 
     
     
       6. The tactile sensor of  claim 1 , wherein said photosensing structure comprises an array of sensing elements. 
     
     
       7. The tactile sensor of  claim 1 , wherein said one or more features comprise roughness of said entity. 
     
     
       8. The tactile sensor of  claim 1 , wherein said one or more features comprise the location, amplitude, or direction of the applied pressure. 
     
     
       9. The tactile sensor of  claim 1 , wherein said one or more features comprise the shape, size, or profile of an object producing said pressure. 
     
     
       10. The tactile sensor of  claim 1 , wherein said one or more features comprise the motion or slip of a surface touching the reflective skin. 
     
     
       11. The tactile sensor of  claim 1 , wherein the sensor has physical properties that are similar to those of human skin. 
     
     
       12. The tactile sensor of  claim 1 , wherein the sensor is formed in the shape of a specified object. 
     
     
       13. The tactile sensor of  claim 1 , wherein the reflective skin is illuminated by two or more light sources of different colors. 
     
     
       14. A method of performing tactile sensing, comprising:
 (a) providing a volume of elastomer capable of transmitting an image;   (b) covering the elastomer with a reflective skin having an inner surface facing the elastomer and an outer surface, wherein the reflective skin comprises particles that non-directionally reflect light incident on the inner surface from within the volume of elastomer;   (c) illuminating the reflective skin through the volume of elastomer with one or more light sources, wherein at least a portion of the light is reflected by the inner surface of the reflective skin;   (d) contacting the outer surface of the reflective skin with an entity, wherein the contact produces pressure that geometrically alters the reflective skin, wherein the alteration causes localized changes in the inner surface of the reflective skin, and wherein the localized changes in the inner surface of the reflective skin cause associated localized changes in the light reflected from the inner surface of the reflective skin;   (e) positioning a photosensing structure to receive a portion of the light reflected from the inner surface of the reflective skin in the form of an image indicating one or more features of the entity contacting the outer surface of the reflective skin.   
     
     
       15. The method of  claim 14 , wherein said volume of elastomer comprises silicone rubber, polyurethane, plastisol, thermoplastic elastomer, natural robber, polyisoprene, polyvinyl chloride or a mixture thereof. 
     
     
       16. The method of  claim 14 , wherein said volume of elastomer comprises a Shore A hardness between 5 and 90. 
     
     
       17. The method of  claim 14 , wherein the volume of elastomer is in the form of a slab. 
     
     
       18. The method of  claim 14 , wherein said photosensing structure comprises a camera. 
     
     
       19. The method of  claim 14 , wherein said photosensing structure comprises an array of sensing elements. 
     
     
       20. The method of  claim 14 , wherein said one or more features comprise roughness of said entity. 
     
     
       21. The method of  claim 14 , wherein said one or more features comprise the location, amplitude, or direction of the applied pressure. 
     
     
       22. The method of  claim 14 , wherein said one or more features comprise the shape, size, or profile of an object producing said pressure. 
     
     
       23. The method of  claim 14 , wherein said one or more features comprise the motion or slip of a surface touching the reflective skin. 
     
     
       24. The method of  claim 14 , wherein the sensor has physical properties that are similar to those of human skin. 
     
     
       25. The method of  claim 14 , wherein the sensor is formed in the shape of a specified object. 
     
     
       26. The method of  claim 14 , wherein the reflective skin is illuminated by two or more light sources of different colors. 
     
     
       27. A method of performing tactile sensing, comprising:
 providing a roller having an outer surface and an inner space;   providing a volume of elastomer capable of transmitting an image disposed on the outer surface of the roller, the volume of elastomer having an inner surface in contact with the outer surface of the roller and a reflective surface, opposite the inner surface, that reflects light incident on the reflective surface from within the volume of elastomer;   illuminating the reflective surface through the volume of elastomer with a light source, at least a portion of the light being reflected by the reflective surface;   rolling the reflective surface along a surface of an entity, thereby sequentially contacting adjacent portions of the reflective surface with adjacent portions of the entity, the contact producing pressure that geometrically alters the contacted portion of the reflective surface, the alteration causing localized changes in the contacted portion of the reflective surface, and the localized changes in the contacted portion of the reflective surface causing associated localized changes in the light reflected from the contacted portion of the reflective surface; and   positioning a photosensing structure inside the inner space of the roller to receive a portion of the light reflected from the reflective surface in the form of a sequence of images resulting from the sequential contact with portions of the entity, each image of the sequence indicating one or more features of the portion of the entity contacting the reflective surface.   
     
     
       28. The method of claim 27, further comprising combining the sequence of images into a single image. 
     
     
       29. The method of claim 28, wherein the combining includes stitching the sequence of images into a panoramic single image. 
     
     
       30. The method of claim 27, the rolling the reflective surface along a surface of an entity comprising holding the roller substantially stationary and moving the entity along the reflective surface. 
     
     
       31. The method of claim 27, the rolling the reflective surface along a surface of an entity comprising holding the entity substantially stationary and moving the reflective surface along the entity. 
     
     
       32. The method of claim 27, further comprising:
 providing a drive wheel disposed in proximity to the reflective surface;   disposing the entity between the drive wheel and the reflective surface; and   rotating the drive wheel to cause the adjacent portions of the entity to pass between the drive wheel and the adjacent portions of the reflective surface, thereby rolling the reflective surface along the surface of the entity.   
     
     
       33. The method of claim 27, the reflective surface comprising reflective particles that reflect light substantially uniformly in all directions, the reflective particles causing the reflective surface to reflect light substantially non-directionally. 
     
     
       34. The method of claim 27, the reflective surface comprising flakes that exhibit at least one of surface roughness, irregular shape, and random alignment relative to each other, the flakes causing the reflective surface to reflect light moderately directionally. 
     
     
       35. The method of claim 27, the reflective surface comprising flakes that are substantially flat, have a mirror-like surface, and are substantially well aligned relative to each other, the flakes causing the reflective surface to reflect light highly directionally. 
     
     
       36. The method of claim 27, the volume of elastomer comprising at least one of silicone rubber, polyurethane, plastisol, thermoplastic elastomer, natural rubber, polyisoprene, polyvinyl chloride. 
     
     
       37. The method of claim 27, the volume of elastomer comprising a Shore A hardness between 5 and 90. 
     
     
       38. The method of claim 27, the photosensing structure comprising a camera. 
     
     
       39. The method of claim 27, the photosensing structure comprising an array of sensing elements. 
     
     
       40. The method of claim 27, the one or more features comprising roughness of the entity. 
     
     
       41. The method of claim 27, the one or more features comprising the location, amplitude, or direction of the applied pressure. 
     
     
       42. The method of claim 27, the one or more features comprising at least one of the shape, size, and profile of the entity producing the pressure. 
     
     
       43. The method of claim 27, the reflective surface being illuminated by at least two light sources of different colors. 
     
     
       44. A sensor comprising:
 a roller having an outer surface and an inner space;   a photosensing structure disposed inside the inner space of the roller;   a volume of elastomer capable of transmitting an image disposed on the outer surface of the roller;   the volume of elastomer having a reflective surface, the reflective surface reflecting light incident on the reflective surface from within the volume of elastomer, the reflective surface being geometrically altered in response to pressure applied by an entity touching the reflective surface, the geometrical alteration causing localized changes in the surface normal of the reflective surface and associated localized changes in the amount of light reflected from the reflective surface in the direction of the photosensing structure, and   the photosensing structure being positioned to receive a portion of the reflected light in the form of an image, the image indicating one or more features of the entity producing the pressure.   
     
     
       45. The sensor of claim 44, further comprising a drive wheel disposed in proximity to the reflective surface, the drive wheel positioned such that rotation of the drive wheel causes the entity to pass between the drive wheel and a portion of the reflective surface, thereby causing the roller to rotate and causing adjacent portions of the reflective surface to sequentially contact adjacent portions of the entity. 
     
     
       46. The sensor of claim 44, the reflective surface comprising reflective particles that reflect light substantially uniformly in all directions, the reflective particles causing the reflective surface to reflect light substantially non-directionally. 
     
     
       47. The sensor of claim 44, the reflective surface comprising flakes that exhibit at least one of surface roughness, irregular shape, and random alignment relative to each other, the flakes causing the reflective surface to reflect light moderately directionally. 
     
     
       48. The sensor of claim 44, the reflective surface comprising flakes that are substantially flat, have a mirror-like surface, and are substantially well aligned relative to each other, the flakes causing the reflective surface to reflect light highly directionally. 
     
     
       49. The sensor of claim 44, the volume of elastomer comprising at least one of silicone rubber, polyurethane, plastisol, thermoplastic elastomer, natural rubber, polyisoprene, polyvinyl chloride. 
     
     
       50. The sensor of claim 44, the volume of elastomer comprising a Shore A hardness between 5 and 90. 
     
     
       51. The sensor of claim 44, the photosensing structure comprising a camera. 
     
     
       52. The sensor of claim 44, the photosensing structure comprising an array of sensing elements. 
     
     
       53. The sensor of claim 44, the one or more features comprising roughness of the entity. 
     
     
       54. The sensor of claim 44, the one or more features comprising the location, amplitude, or direction of the applied pressure. 
     
     
       55. The sensor of claim 44, the one or more features comprising at least one of the shape, size, and profile of the entity producing the pressure.