Apparatus for determining when a gripper or hand (30) resiliently mounted on a robot arm by a set of compliant springs (52A-52C), strikes or makes contactwith an objectthat impedes or limits hand movement, includes a lightsource (60) and a light-sensitive device (72) cooperatively mounted one on the robot hand and the other on the robot arm, the position of optically focused light from the light source (60) impinging on the light-sensitive device (72) enabling signals representing the relative position of the robot arm and robot hand to be continuously generated. Relative movement between the robot arm body and the robot hand (30) normally resulting from contact between a motion-impeding object and the robot hand causes the light-sensitive device to generate a signal indicative of such object contact and/ or extent of relative hand-to-robot arm body movement. This signal may be employed, for example, either to terminate movement of the arm or to cause a particular force to be applied to the object contacted by the robot hand.
CONTROLLING MOVEMENT OF A ROBOT ARM