Design analysis and control of a magnetorheological fluid based torque transfer device

In this paper, a magnetorheological (MR) torque transfer device is presented. Design, modeling and control aspects are particularly emphasized. MR fluids possess the unique ability to undergo dramatic and nearly completely reversible changes in their rheological properties under the application of a magnetic field. These controllable fluids can serve as quiet, rapid interfaces between electronic controls and mechanical systems. One area of application is to use these fluids as actuators. The MR torque transfer device proposed here can function as either a clutch or a brake. A model providing torque output as a function of magnetic field and rotational speed is proposed and verified experimentally. An acceptable correlation is found between model predictions and clutch performance. A PID controller is designed and experimentally evaluated. In the experimental control setup, the output variables are the position, velocity, and torque at the output shaft and the control input is the electromagnet current. The closed loop performance of the system was studied for torque regulation and torque tracking. Both regulation as well as tracking torque control were successfully achieved with this controller.