Finite element modelling and robust control of fast trilayer polypyrrole bending actuators

Abstract

Conjugated polymer actuators can be employed to achieve micro scale precision positioning, having a wide range of application including biomimetic robots, and biomedical devices. They can operate with low voltage while producing large displacement, 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 accurate and robust control of the actuator difficult. There has been extensive research on modeling the electrochemical dynamics of polypyrrole bending actuators. However the mechanical dynamics modeling of actuator remains to be unexplored. In this paper finite element modeling and robust control of fast trilayer polypyrrole bending actuators is proposed. In the modeling part the infinite-dimensional admittance model of actuator will be replaced with a family of linear uncertain transfer functions based on Golubev Method. Further model development will take into account the proper mechanical dynamics, which is essential, when using fast conducting polymer actuators. The purposed modeling approach will be validated based on the existing experimental data. In the controlling part the robust control QFT will be applied to control the highly uncertain dynamics of the conjugated polymer actuators while the actuator carrying variable tip loadings. Finally the analysis of design shows that QFT controller has consistent and robust tracking performance. © 2011 - IOS Press and the authors. All rights reserved.