Design and testing of a dual-mode magnetorheological actuator with magnetic decoupling

Purpose This study aims to propose an innovative design scheme for an integrated magnetorheological flexible actuator, aiming to achieve functional integration of active stiffness adjustment and flexible braking to enhance actuator performance. Design/methodology/approach By synergistically configuring permanent magnets and excitation coils in a hybrid magnetic circuit structure, the permanent magnets enable power-off self-locking while cooperating with the excitation coils to establish a dual-mode actuation system. A mathematical model was developed based on the magnetic circuit theory, and finite element simulations were used to validate the magnetic decoupling characteristics between the transmission and braking modules. The control performance was further evaluated through prototype experiments. Findings Experimental results demonstrate that in the transmission mode, the output torque exhibits a linear relationship with the excitation current, reaching 30 N·m at 3 A. In the braking mode, a reverse excitation of 1.3 A enables dynamic torque regulation from 15 N·m (zero-current self-locking) to 3.2 N·m. Originality/value This study innovatively introduces a magnetically decoupled dual-mode drive architecture for magnetorheological flexible actuators, integrating power-off self-locking and dynamic braking functionalities. This breakthrough overcomes the coupling limitations between stiffness adjustment and braking performance in conventional actuators, offering high integration density and strong functional expandability.