Novel nonlinear variable structure servo controller

A novel variable structure controller which ensures that the system response speed is time optimal was presented. It employs the slide mode control which possesses the Time-Optimal-Switching-Surface when the state is far from the equilibrium one, and it can automatically turn into PID controller when the state is near the equilibrium point. This controller has the following two distinguishing features. (1) It possesses simultaneously five advantages: (a) nearly time-optimal response speed, (b) very small overshoot, (c) strong robustness, (d) no static error, (e) no chattering. (2) It can save control energy and its simple control law can be implemented by either analog or digital means.