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 of view. Output feedback‐based robust tracking control strategies are proposed in this work for that purpose. First, a high‐order sliding‐mode observer is used to estimate the oscillator states from the measurable output and to identify some types of disturbances. Then, five different continuous sliding‐modes controllers (Continuous‐SMCs) are provided to robustly track a desired time‐varying trajectory, exponentially or in a finite time, for the Van der Pol oscillator despite the presence of external disturbances. 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.