Strange attractors and chaos control in a Duffing–Van der Pol oscillator with two external periodic forces

An anharmonic Duffing–Van der Pol oscillator with two external forces is considered. By applying numerical results, strange attractors are presented and the chaotic behaviour is investigated. The problem of directing a chaotic state of the system to a periodic orbit is studied. By assuming that the exact model of the system is not known and that the position is the only state available for measurements, the controller comprises a linearizing-like feedback and an estimator. Simulations are provided to illustrate the performance of the controller.