observer-based control for a modified duffing system using twisting algorithm

this paper presents a new observer-based control scheme for a class of nonlinear systems. in the proposed method, nonlinear observer and twisting algorithm controller are employed to realize a sensor-less control strategy for complex systems which makes use of non measurable process information instead of installing as many sensors as possible. due to lack of availability of the complex system states, controlling of them will be faced with undesirable performance. this deficiency can be solved with adding observer in the control strategy. in order to estimate unavailable states, an adaptive neural network observer is considered in the present article. this observer is tuned online and no exact information of the nonlinear function in the observed system is required. also, to realize control purpose, 2nd order sliding mode controller called twisting algorithm is located in the close loop structure. this control strategy is implemented on the modified duffing chaotic system and the simulation results confirm the capability of this method.