Robust Position Control of Dielectric Elastomer Actuators Based on LMI Optimization

This paper develops a model-based control strategy for a bistable positioning system based on a dielectric elastomer. The motion is generated by the electrostatic compressive force between two compliant electrodes applied on the surface of the elastomer. The membrane is connected to a bistable spring that acts as a biasing element and significantly extends the possible stroke. Such a design choice, however, makes the system strongly nonlinear and unstable in open-loop. Starting from the extension of a dynamic model developed for a simpler version of the actuator, this paper proposes a strategy based on robust control design tools for linear parameter-varying systems. The approach guarantees both stability and worst case performance in the whole operating range of the system. Both simulations and experiments are used to assess the advantages of the proposed design method.