Identification and control of a trilayer conjugated polymer actuator
This paper presents the effect of three uncertain parameters on a recent model of conjugated polymer actuators and implements a robust controller based on the model developed for this actuator. These uncertain parameters are the diffusion coefficient (D), the charge capacitance (C d ) and the charge-to-strain ratio (α), which are difficult to measure directly. The parameter estimation method used in this article is based on a Bayesian cost function, and gives us an insight on how much the estimation can be trusted, which is useful information for the design of controllers. Results indicate that the charge capacitance is the best known parameter and should therefore be designed for with greater confidence in its value, while the controller should be much more robust with respect to the diffusion coefficient and the charge-to-strain ratio. Based on this finding, a robust controller based on the quantitative feedback theory is implemented and compared with a conventional PID controller. This results in an improvement of the control performance.