LMI-based design of PI controllers for micropositioning dielectric electro-active polymer membranes

This paper develops a control system for a bi-stable positioning system based on a dielectric electro-active polymer membrane. The motion is generated by the deformation of the membrane caused by the electrostatic compressive force between two compliant electrodes applied on the surface of the polymer. A bi-stable spring is used to pre-load the membrane, allowing high stroke but producing at the same time a strong non-linear behavior. The paper proposes a detailed electro-mechanical model of the system, which is subsequently used to develop a model-based PI control law providing precise tracking and worst-case performance guarantees. The design strategy is validated both in simulations and experiments.