Improvement of response properties of MR-fluid actuator by torque feedback control

Magnetorheological (MR) fluids are substances that respond to an applied magnetic field with a change in their theological behavior. Though they are functionally similar to electrorheological (ER) fluids, MR fluids exhibit much higher yield strengths for the applied magnetic fields than ER fluids for the applied electric fields. The devices using MR fluids have an ability to provide high-torque, low-inertia, a safe device and simple interface. In this study, we report on an actuator developed using the MR fluid, which consists of an input part, an output part and an MR fluid clutch between them. First, the basic experiments are examined to investigate the characteristics of the actuator. Next, the torque control system of the MR-fluid actuator is proposed. Finally, the closed-loop control experiments were carried out and it is confirmed that the torque-feedback control is effective for improving the response properties of MR actuators.