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 rubber, 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 tactile sensor comprising:
 a volume of elastomer for transmitting an image, the volume of elastomer having a fluorescent skin, the fluorescent skin becoming a source of light emission in response to absorbing energy from exposure to light that excites the fluorescent skin, the fluorescent skin being elastomeric and deformable in response to pressure applied by an object touching the skin, and the deformation causing localized changes in a surface normal of the fluorescent skin;   a photosensing structure, the photosensing structure being positioned to receive at least a portion of the light emitted from the fluorescent skin in the form of an image, the image indicating one or more features of the object producing the pressure; and   a light source, the light source being disposed relative to the volume of elastomer to expose the fluorescent skin to light energy absorbed by the fluorescent skin that excites the fluorescent skin, and the localized changes in the surface normal of the fluorescent skin causing corresponding localized changes in an amount of emitted light received by the photosensing structure.   
     
     
       28. The tactile sensor of claim 27, the localized changes in the surface normal of the fluorescent skin causing corresponding localized changes in an amount of light received by the fluorescent skin from the light source, the localized changes in the amount of light received by the fluorescent skin causing the corresponding localized changes in an amount of emitted light received by the photosensing structure. 
     
     
       29. The tactile sensor of claim 27, the photosensing structure comprising a camera. 
     
     
       30. The tactile sensor of claim 27, the photosensing structure comprising a plurality of cameras positioned at different orientations relative to the fluorescent skin. 
     
     
       31. The tactile sensor of claim 27, comprising a plurality of light sources disposed at different azimuths relative to the fluorescent skin. 
     
     
       32. The tactile sensor of claim 27, the fluorescent skin being substantially nonreflective to the light emitted from the fluorescent skin. 
     
     
       33. The tactile sensor of claim 27, the fluorescent skin being substantially opaque to the light emitted from the fluorescent skin. 
     
     
       34. The tactile sensor of claim 27, the fluorescent skin being substantially opaque to the light that excites the fluorescent skin. 
     
     
       35. The tactile sensor of claim 27, the light source being an ultraviolet light source. 
     
     
       36. The tactile sensor of claim 35, the light source being a black light source. 
     
     
       37. The tactile sensor of claim 27, the light source being a flashed source of light. 
     
     
       38. The tactile sensor of claim 27, the light source being disposed at a grazing angle relative to the fluorescent skin. 
     
     
       39. A method of tactile sensing comprising:
 providing a volume of elastomer for transmitting an image, the volume of elastomer having a fluorescent skin;   exposing the fluorescent skin to light from a light source that causes the fluorescent skin to absorb energy from the light source that excites the fluorescent skin and causes the fluorescent skin to become a source of light emission;   contacting the fluorescent skin with an object to cause the fluorescent skin to deform in response to the contact by the object, the deformation causing localized changes in a surface normal of the fluorescent skin and associated localized changes in the amount of emitted light received by a photosensing structure; and   receiving in a photosensing structure at least a portion of the light emitted from the fluorescent skin in the form of an image, the image indicating one or more features of the object producing the pressure.   
     
     
       40. The method of claim 39, the localized changes in the surface normal of the fluorescent skin causing corresponding localized changes in an amount of light received by the fluorescent skin from the light source, the localized changes in the amount of light received by the fluorescent skin causing the corresponding localized changes in an amount of emitted light received by the photosensing structure. 
     
     
       41. The method of claim 39, the photosensing structure comprising a camera. 
     
     
       42. The method of claim 39, the receiving in the photosensing structure at least a portion of the light emitted from the fluorescent skin comprising receiving the at least a portion of the light in a plurality of cameras, each camera of the plurality being positioned at an orientation that differs from any other camera relative to the fluorescent skin. 
     
     
       43. The method of claim 39, the illuminating the fluorescent skin with the light source comprising using a plurality of light sources disposed at different azimuths from each other relative to the fluorescent skin. 
     
     
       44. The method of claim 39, the fluorescent skin being substantially nonreflective to the light emitted from the fluorescent skin. 
     
     
       45. The method of claim 39, the fluorescent skin being substantially opaque to the light emitted from the fluorescent skin. 
     
     
       46. The method of claim 39, the fluorescent skin being substantially opaque to the light that excites the fluorescent skin. 
     
     
       47. The method of claim 39, the illuminating the fluorescent skin with the light source comprising using an ultraviolet light source. 
     
     
       48. The method of claim 47, the illuminating the fluorescent skin with the light source comprising using a black light source. 
     
     
       49. The method of claim 39, the illuminating the fluorescent skin with the light source comprising using a flashed source of light. 
     
     
       50. The method of claim 39, the illuminating the fluorescent skin with the light source comprising disposing the light source at a grazing angle relative to the fluorescent skin.