A robust optimal controller based on sliding mode control(SMC)was designed for the nonlinear uncertain continuous stirred tank reactor(CSTR).Input-output linearization was used to linearize the nonlinear CSTR

and the only assumption on the uncertainties was that they are bounded. Defining the integral sliding mode surface to assure the steady errors of closed-loop system be zero. Equivalent control law improving the transient characteristics was designed to minimize the quadratic cost function.The adaptive switch control gain could drive the state variables to the sliding surface as soon as possible without causing too much chattering problem

and the uncertainties of the controlled CSTR could be compensated.Simulation results showed that the proposed approach was a practical and valid scheme for the nonlinear uncertain chemical process.