Precise Position Control of Robot Arm Using Liquid Crystal Electrorheological Fluid Based on H.INF. Control Theory.

In general, a semiclosed loop method which utilizes the signal obtained from an encoder mounted on a servomotor, is adopted in the control of industrial robots. In this method, the position of the end-effector is not controlled very accurately. Therefore, we aim to apply a closed loop control which uses the absolute position measured directly at the end-point. However, it is very difficult to control the arm based on this method because of the flexibility of the driving system. In this study, a robot arm with the damper using electrorheological fluid is developed in order to improve the stability. Then the closed loop method is applyed to the positioning of the end-point of the arm. The feedback-controller is derived by using the mixed sensitivity problem of H∞ control theory.