Importance

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Abstract

A gripper assembly for a robotic arm includes two opposing elements displaced by means of a worm gear arrangement for grasping an object positioned therebetween. The worm gear is driven by a rotary drive motor with a torsion spring coupling the drive motor shaft to the worm. First and second shaft encoders are respectively mounted to the drive motor shaft and the worm shaft. First and second pairs of optical sensors respectively coupled to the first and second shaft encoders detect the angular speed and displacement of the drive motor shaft and the worm. With the torsion constant of the spring known, the force applied by the gripper assembly which is proportional to the angular displacement of the worm may be accurately determined and controlled. In addition, the size of the object grasped by the gripper assembly may be determined. By comparing these operating parameters with selected values, the gripper assembly may be precisely controlled such as by means of a microcomputer.

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First Claim