NASA 's Jet Propulsion Laboratory, Pasadena, California
A "smart" hand for a remote manipulator not only senses forces acting on it and detects the presence of objects in its immediate vicinity but also processes the sensory data and controls its gripping claws. The hand thereby reduces the computational load on the control computer of the manipulator system. The hand includes a wrist body and two opposing jaws with sets of claws that mesh with each other (see figure). Sensors in the wrist measure forces and torques on the hand in three orthogonal directions. Sensors in the claws measure gripping forces. Proximity sensors will be added to the claws to detect objects at distances up to at least 6.3 cm from the claw surfaces. These sensors give information on the distance of objects and provides the raw data for computation of the position, orientation, and velocity of the hand. The grasping-force sensors on the jaws are strain gauges connected in bridge circuits. Eight additional strain- gauge bridges in the wrist measure forces and torque there. The proximity sensing will be done by light emitters and detectors arranged in pairs over the hand. Light reflected by an object from an emitter to a detector varies with the distance of the object. The local processor in the hand illuminates the emitters in sequence and simultaneously reads the digitized output of the corresponding detectors in the pairs. The analog signals from the sensors are converted to digital signals and fed in parallel to a local processor in the hand. This processor puts the signals into serial form and sends them, via a slipring, to a signal processor on the stationary side of the rotary wrist. The signal processor computes parameters for the operator's display. The processor also receives command signals from the control computer. It interprets the coded commands, calculates the required hand response, and generates control signals for the dc rnotor that drives the hand.
Point of Contact:
Antal K. Bejczy
Mail Stop 198-219
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena CA 91109
818-354-4568
bejczy@telerobotics.jpl.nasa.gov
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Maintained by: Dave Lavery
Last updated: May 10, 1996