5.4 Compensating for location uncertainties

Standard approaches to gripper design often implicitly assume that the objects to be grasped are in accurately known positions. In practice, grippers and fixtures must accommodate positioning uncertainties due to such factors as vision resolution and robot calibration limits. These uncertainties can reduce the accuracy with which a part is manipulated, can result in jamming, or lead to damage of the parts or tooling. Conventionally, gripper and fixture designs incorporate tolerances larger than the expected part position uncertainty.

It has been shown, however, that fixtures can be des-igned to improve the precision of part locations through the act of manipulation [24, 25, 26]. This can be done by designing contact surfaces that guide imprecisely located objects into known positions when a gripper is closed or a part is inserted into a fixture. We propose that such design techniques can be incorporated within our method for automated tooling design. This proposition is currently being explored in continuing research.

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