Stable Prehension of Objects by the Robot Hand with Elastic Fingers

Abstract

In general, robot hands in industrial uses have specifically designed fingers corresponding to the shapes of work pieces to be handled. However, the more versatile hands are desirable in case of advanced jobs such as assembly process, because various types of mechanical parts must be handled.This paper describes the design and control problem of universal robot hand which has elastic fingers and can grip various workpieces at the proper position suitable for their shapes. We propose an adaptive prehension system which consists of a newly designed universal hand, an ITV camera and a mini-computer. The universal robot hand has three elastic fingers which are driven by pulse motors through coil springs.We discuss the adaptive prehension process by the above robot system. The workpieces are caught by the ITV camera and the data of the peripheral shapes are sent to the mini-computer. The computer determines the finger arrangement at the stable prehension based on the potential function theory of prehension system, which we've ever introduced as an criterion of stability. An effective and simple computation algorithm is proposed to meet an on-line use of the robot in. the industrial application. The experiment verified the usefulness of the developed system.