Takagi-Sugeno fuzzy modelling and parallel distributed compensation control of conducting polymer actuators

Abstract

Conducting polymer actuators are used in a diverse range of applications including biomimetic robots and biomedical devices. In comparison to robotic joints, they do not have friction or backlash, but on the other hand, they have complicated electro-chemo-mechanical dynamics which makes modelling and control of the actuator really difficult. In addition they also have the disadvantages of creep, hysteresis, and highly uncertain and time-varying dynamics. In this paper a Takagi-Sugeno (T-S) fuzzy model is used to represent the uncertain dynamics of the actuator, and the resulted fuzzy model is validated using experimental data. A system that consists of fuzzy state feedback to a PI controller is designed on the basis of the obtained T-S fuzzy model using the parallel distributed compensation scheme. The sufficient conditions for the existence of such a controller are derived in terms of linear matrix inequalities. The obtained results show that the designed controller can achieve a good control performance despite the existence of uncertain actuator dynamics.