Object-Handling System for Manual Industry

An object-handling system for manual industry is described. This system is designed to have a compact structure and to accomplish multiple prehension and flexible motion for manual tasks. The system has three fingers which have structures similar to those of a human. Namely, these fingers are composed of three, four, and four joints, respectively, and can perform not only such simple motions as bending and extending but also such lateral flexing motions as adduction and abduction. The kinematics of the system is discussed in a rectangular coordinate system. The general solution for the finger joint is obtained by solving a fourth-degree equation. The control mode of each finger joint is suitably changed between position and torque control, and each joint is controlled by a hardware servo system. Cooperative motions among the fingers are easily realized by means of the hardware servo system. In an experiment of swing motion, cooperative motion based on a force control is accomplished between the right and left fingers without dropping the object. Bar turning and sphere turning are accomplished smoothly by a computer control in which control signals for finger joints are generated by interpolating a sequence of set points that has been stored in the computer in the teaching process.