Motion control of direct-drive motor by a homogeneous ER fluid

Since a direct-drive (DD) motor system doesn't have the reduction gear, the structure of the servo system can be simple and stiff. On the other hand, in the DD system, the disturbance torque directly influences the accuracy o f the motor control. The high servo gain is effective and important for red ucing the influence of the disturbance torque. However, the high servo cont rol often makes the control system unstable or vibratory. Therefore, the se rvo gain must be lowered for assuring stability, and the influence of the d isturbance becomes serious. In this study, the DD meter system using an ER fluid damper is discussed. By applying the ER damper to the DD motor system , it is possible to obtain the mechanical damping and to realize a high ser vo gain in the motion control. Finally, thr effectiveness of the proposed s ystem is confirmed experimentally.