Tech Briefs

A miniature load sensor has been developed as a prototype of tactile sensors that could fit within fingertips of anthropomorphic robot hands. The sensor includes a force-and-torque transducer in the form of a spring instrumented with at least six semiconductor strain gauges. The strain-gauge wires are secured to one side of an interface circuit board mounted at the base of the spring. This board protects the strain-gauge wires from damage that could otherwise occur as a result of finger motions.

On the opposite side of the interface board, cables routed along the neutral axis of the finger route the strain-gauge output voltages to an analog-to-digital converter (A/D) board. The A/D board is mounted as close as possible to the strain gauges to minimize electromagnetic noise and other interference effects. The outputs of the A/D board are fed to a controller, wherein, by means of a predetermined calibration matrix, the digitized strain-gauge output voltages are converted to three vector components of force and three of torque exerted by or on the fingertip.

This work was done by Myron A. Diftler and Toby B. Martin of Johnson Space Center, Michael C. Valvo and Dagoberto Rodriguez of Lockheed Martin Corp., and Mars W. Chu of Metrica, Inc. MSC-23910-1

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Miniature Six-Axis Load Sensor for Robotic Fingertip (reference MSC-23910-1) is currently available for download from the TSP library.

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