Robustness enhancement of proportional Q-integral multiobserver in the case of non-stationary sinusoidal unknown inputs

This paper deals with the robustness enhancement of proportional Q-integral multiobserver in the case of non-stationary sinusoidal unknown inputs. The multimodel approach is proposed in order to overcome the complexity problems of nonlinear systems. The proposed multiobserver uses the multi-integral strategy in order to provide a simultaneous estimation of the state and unknown inputs. A new robust strategy allowing the minimization of the non-stationary sinusoidal unknown inputs impact on the estimation error is developed. The significance of the proposed study is illustrated via a simulation example.