Method and apparatus for positioning a robotic end effector

摘要

A robotic end effector and operation protocol provide for a reliable grasp of a target object irrespective of the target's contours. A robotic hand 30 includes a plurality of jointed fingers 31-34, one of which, like a thumb 31, is in opposed relation to the other. Each finger comprises at least two jointed sections, and is provided with reflective proximity sensors, one on the inner surface of each finger section. Each proximity sensor comprises a transmitter of a beam of radiant energy and a receiver for receiving reflections of the transmitted energy when reflected by a target object. On the fingers opposed to the thumb, the proximity sensors 41 on the outermost finger sections are aligned in an outer sensor array and the sensors 42 on the intermediate finger sections and sensors 43 on the innermost finger sections are similarly arranged to form an intermediate sensor array and an inner sensor array, respectively. The invention includes a computer system 55 with software and/or circuitry 56 for a protocol comprising the steps in sequence of (1) approach axis alignment to maximize the number of outer layer sensors which detect the target; (2) non-contact contour following of the target by the robot fingers to minimize target escape potential; and (3) closing to ridigize the target including dynamically re-adjusting the end effector finger alignment to compensate for target motion. A signal conditioning circuit 52 and gain adjustment 57 are included to maintain the dynamic range of low power reflection signals.