Non-smooth observer for sandwich systems with backlash
基于非光滑观测器的间隙三明治系统状态估计

Industrial systems involving backlash, such as mechanical transmission systems and hydraulic systems, can be described by so-called sandwich systems with backlash. A novel non-smooth observer is proposed to handle the state estimation for sandwich systems with backlash. Based on the characteristics of the system, a non-smooth state-space equation is constructed by using the separation principle. A non-smooth observer is developed based on the obtained state-space equation. The observer switches automatically among different operating zones according to the changes of operation conditions. The convergence of the non-smooth observer is discussed. The application of this observer to a practical hydraulic servo system is realized. The comparison of tracking performances of the hydraulic servo system is made between the proposed non-smooth scheme and the conventional method. It is shown that the proposed non-smooth approach is with much better estimated performance.