Importance

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Abstract

A resilient gripper pad stores deformation energy just before the gripped object starts to slip, then rapidly accelerates as it suddenly releases the energy in the springback to rest position. An accelerometer in the resilient pad (corrected for ambient acceleration by differentiation with a nearby second accelerometer) provides information by which the control computer of a closed loop robot system mandates the manipulation of objects by controlled slipping. Controlled transitions of gripping (releasing) action evoked by the control computer provide related sequences of grip (slide) events, with one or more slip (pad chatter) events intervening at the threshold. Prior to the slide, there is an instant when the gripped object starts to slip on a slip pad on one digit of the gripper, but remains frictionally gripped by a resilient pad on the opposing digit. During this instant, the resilient pad deforms downward because of gravity on the gripped object. Next, when gripping force relaxes just a little more, the object slides free and the resilient pad springs back to its rest position. Two accelerometers, one mounted in the resilient pad to experience springback acceleration, and the other mounted in a complementary slip pad to experience ambient acceleration, are differentially compared. A computer manipulates signals related to motion experience of the gripper (grip or release) and detection (or absence) of springback acceleration, determines gripping, slipping or sliding status, and mandates the appropriate gripper action.

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First Claim