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.
This paper is aimed at developing a novel multifunctional actuator utilizing magnetorheological (MR) fluids. As a key component for assistive knee braces, the actuator can work with multiple functions as motor, clutch and brake in order to meet the requirement of normal human walking. In this paper, design considerations including configurations, materials selection, mechanical and electromagnetic designs are illustrated. Prototype of the multifunctional actuator is fabricated, and each of its functions is investigated. Control strategies for mimicking normal human walking using the multifunctional actuator are illustrated. Adaptive control algorithm is adopted. Experiments on torque and speed tracking are conducted. The results show that the developed multifunctional actuator is promising for assistive knee braces.
This paper is aimed to develop a new actuator used in assistive knee braces for helping elderly or disabled people to recover their mobility. In the design, magneto-rheological (MR) fluids are integrated into the actuator to provide controllable torque and improve the braking control performance. With MR fluids, the actuator possesses multiple functions as motor, clutch, and brake while meeting the requirement of normal walking as well. In this paper, design considerations including actuator configuration, magnetic circuit and influence of permanent magnet on MR fluids are discussed. Finite element model of the actuator is built and analyzed. Modeling of the actuator in different functions is presented. A prototype of the actuator is fabricated and tested. Braking torque control of the actuator is investigated. The results show that the developed multifunctional actuator is promising for assistive knee braces.
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