Augmented sliding-mode control of an ultra-precision positioning system

In this study, we designed an augmented robust controller for an ultra-precision positioning system. The control algorithm includes modified sliding-mode control with a new switching surface and linear quadratic (LQ) control for optimal feedback gain. A nanometric scale positioning system is especially vulnerable to parameter uncertainties and external disturbances. To solve this problem, we propose an augmented system that adopts two auxiliary states: state estimates and control input. We demonstrated the robust performance of the proposed control algorithm through a comparison with LQ control.