A Study of Semi-Closed Servo System of Elastic Robot Arm.

Abstract

Recently, high speed and high precision have become very important qualities in industrial robots. To achieve high precision, it is important to reduce the vibration of the arm tip. However, high speed increases vibration. When the elasticity of the reduction gear and other components can not be neglected, the natural frequency becomes small, and vibration problems appear. In this study, we consider a one-link robot which contains a motor, a reduction gear, and an arm as a semi-closed servo system and investigate the relation between mechanical parameters and gains of the controllers. The optimum gains are determined for the position pd-controller analytically and it is shown that the optimum dynamic property is obtained when the ratio of the inertial moments of the motor and the arm is 1:4. We propose methods for obtaining an inertial moment ratio of 1:4 and study the dynamic property in relation to the input and the disturbance.