Real-time control for a zero-gravity robotic end effector

A position controller for the gripper portion of a zero-gravity robotic end effector has been developed and tested. A hybrid force/position controller is used. Sensory data available to the controller are obtained from an array of strain gauges and a linear potentiometer. It was determined that an optimal control exists which transfers the initial finger opening to the desired opening in minimum time. This time optimal control is unique and is constant with value equal to plus or minus maximum armature voltage, the value of the control depending on the relative location of the desired final position. A force controller has been developed and tested which is based only on the holding force, perpendicular to the finger face. In addition, a neural network mapping has been determined to compute contact force and location from the strain data when the tangential force components are constrained to be zero