Sliding mode variable structure control of multi-model switching for rolling mill hydraulic servo position system

The jumping problem of elastic stiffness coefficient caused by different working condition of the rolling mill hydraulic servo system is discussed. Firstly,a nonlinear multiple models set for hydraulic ser-vo system was established on different conditions. Secondly,the locally adaptive sliding mode variable structure controller for each sub-model was designed by selecting the steady common sliding surface. It is proved that the system states tend to be with the common sliding surface from arbitrary initial conditions by using Lyapunov stability theory,so that the stability of the whole variable structure switching control system can be ensured. In order to diminish the bad effect caused by system parameter jumping,the opti-mal performance index was considered as the rule of switching control which can implement the switching among sub-models controller. Finally,the simulation results demonstrate that the designed multi-model switching adaptive sliding-mode controller can ensure not only good dynamic and static performance for rolling mill hydraulic servo position system,but also good robustness for the system parameter jumping.