On fast finite-time extended state observer and its application to wheeled mobile robots

Active disturbance rejection control (ADRC) is an effective technique to handle uncertainties. Extended state observer (ESO), as the key component of ADRC, is often introduced to estimate the states and the total disturbance. Some finite-time extended state observers (FTESOs) were studied to improve the estimation performance. However, the existing FTESOs only use the fractional power term as the correction item, whose convergence rate is small when the estimation error is far from the equilibrium. To overcome this drawback, this paper proposes a fast finite-time extended state observer (FFTESO) for a type of nonlinear systems with uncertainties, by which all the states and the total disturbance of the systems are estimated. The designed FFTESO is composed of three terms. Compared with the traditional FTESO, the linear term is utilized to speed up the convergence rate. Besides, the switching term is employed to guarantee the finite-time convergence. Finally, the FFTESO-based finite-time controller is developed for the wheeled mobile robot. Experimental results demonstrate the validation of the proposed method.