Stabilizing unstable equilibrium points of chaotic systems using PI regulator

In this paper, by using the PI regulator and variable structure technique, a new method is presented for stabilizing unstable equilibrium points of chaotic systems. Based on the theory of nonlinear ordinary differential equations, a simple criterion is derived for designing the controller gains for stabilization and tracking, in which control parameters can be selected via the pole placement technique of linear control theory. More importantly, this control method has a simple controller structure, high robustness against system parametric variations, and strong rejection of external constant disturbances.