Modeling and optimal control of microscale SMA actuators

The paper presents an optimal control approach to shape memory alloy (SMA) actuators. Like other active materials, e.g., piezoceramics or magnetostrictive materials, SMAs exhibit a highly non-linear and hysteretic behavior. In certain applications, in particular those with high driving frequencies like MEMS (Micro-Electro-Mechanical Systems) applications, this is known to lead to a breakdown of standard control algorithms. The optimal control approach overcomes this problem by including a model for the hysteretic behavior, and allows criteria like maximal speed and minimal energy consumption to be taken into account. To illustrate the potential benefits of the method, the performance is compared to that of a standard PI control.