Abstract: This paper proposes a robust control approach which uses state feedback of a model similar to a plant to improve the performance of the system. It also utilizes the sign feedback of the output error between the plant and the model and the sign inner model to enhance the system's robustness while various uncertainties exist. Theoretical analysis and simulations show its strong robustness both in stability and performances.

Key words: model state feedback, sign feedback of output error, sign inner model, robust control