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A novel shape memory alloy (SMA) actuator consisting of a cylindrical rod with a single off-axis embedded one-way SMA wire is first described. The actuators, acting as both actuating elements and executing elements, are compact enough to be used in miniature robot system. The practical specifications of the SMA wire and the flexible rod were determined based on a series of formulae. The mechanical properties of the actuator are also investigated.
After time domain open loop experiments and simulation, the simple model, a single integrator, is derived. A variable structure controller was then applied to the novel actuator. The feedback switches according to the sign of the curvature error. It was verified that the controller could realize smooth and robust control of the actuators.