A new extended state observer for output tracking of nonlinear MIMO systems

In this paper, we investigate the output tracking problem for a class of nonlinear uncertain multi-input multi-output (MIMO) systems by active disturbance rejection control (ADRC) approach. A new extended state observer (ESO) is developed to estimate both the unmeasured state and uncertainty, which produces smaller peaking value and higher accuracy compared with existing linear ESO under the same tuning gain. An output feedback controller is designed based on the proposed ESO to compensate the total disturbance. The practical convergence of ESO and output tracking are established. Numerical simulations are presented to illustrate the effectiveness and advantages of the proposed method in terms of peaking value reduction and high accuracy tracking.