Experimental study of robust output-based continuous sliding-modes controllers for Van der Pol oscillator

Robust output tracking control of Van der Pol oscillator is an important practical problem from an application point ofview. Output feedback-based robust tracking control strategies are proposed in this work for that purpose. First, a high-ordersliding-mode observer is used to estimate the oscillator states from the measurable output and to identify some types ofdisturbances. Then, five different continuous sliding-modes controllers (Continuous-SMCs) are provided to robustly track adesired time-varying trajectory, exponentially or in a finite time, for the Van der Pol oscillator despite the presence of externaldisturbances. The closed-loop stability for each Continuous-SMC is given based on input-to-state stability properties. Finally,experimental validations are also provided to show the feasibility of the proposed controllers in real time.