Operator-based robust control for nonlinear system with input and output nonlinearities

Abstract

With the development of modern technology, the practical systems become much more complex, smart actuators and sensors, such as piezoceramic and magnetostrictive material based ones, have widely been used in reality due to its variety of advantages. Therefore, nonlinearities, including not only the dynamical nonlinearity but also the non-smooth nonlinearities both in actuators and sensors, should also be considered. However, the output nonlinearities, namely, non-smooth effects from sensors have always been ignored. In this paper, robust control for nonlinear system with input and output nonlinearities is considered by using operator based robust right coprime factorization approach. In details, generalized Prandtl-Ishlinskii (PI) hysteresis model is used for describing the input and output nonlinearities for its excellent characters. Moreover, by using operator based robust right coprime factorization approach, the control system design structure including feedforward and feedback controllers for nonlinear uncertain system is presented, and sufficient conditions for the controllers to be satisfied are also derived. Based on the proposed conditions, influence from input and output nonlinearities is rejected, the systems are robustly stable and output tracking performance can be realized.