A novel multifunctional rotary actuator with magnetorheological fluid

In some environments with very limited working space, an integrated actuation device with multiple functions would be desirable. This paper is aimed at developing a novel magnetorheological (MR) fluid based multifunctional rotary actuator. To decrease the dimension of the actuation device while enhancing the functionality, a motor part and MR fluid are integrated into one device. With MR fluid, the actuator possesses multiple functions as motor, clutch, and brake. In this paper, the configurations and design details of the motor part and clutch/brake part are illustrated, and the operating principle of the actuator is discussed as well. The torques of the motor part and clutch/brake part are derived. The finite element method is utilized to analyze the magnetic circuits, the influence of permanent magnets on the MR fluid, and the magnetic flux distribution. A prototype of the actuator is fabricated and each function is tested. The results show that the developed actuator is promising for applications which require multiple functions with compact size.