Design and Control of a Series of Linear and Rotary Actuators based on Shape Memory Alloy Wires

This paper introduces a family of modular electro-mechanical actuators based on Shape Memory Alloy (SMA) materials and featuring reduced number of moving parts and direct control schemes, elements which are essential for many application areas requiring fast design, real-time control and high performance. The approach consists into presenting the design, modeling, development, characterization and finally control of a series of actuators capable of linear or angular stroke. The main advantage of the proposed design approach resides in its modularity, allowing a rapid development in diverse dimensions according to the specified performances. For that, the design is emphasized on the conversion principle of the shape memory effect in the useful mechanical work, specific calculations for the mechanic and electronic subsystems, the operation and the integration of the electronic module in the mechanical structure. Afterwards, the characterization of the actuators is detailed. Finally, a closed-loop controller scheme is proposed for the actuators, using an original dual-input -single-output controller in order to improve both response time and linearity. The closed-loop experiments were performed on the linear actuators and demonstrate the efficiency of the proposed scheme.