Robust Reference Tracking of Linear Uncertain Systems via Uncertainty Estimation and Composite Control

For linear systems with uncertainties and external disturbances, we present an uncertainty estimation and composite control (UECC) to achieve reference tracking and uncertainty estimation simultaneously. In this proposed UECC, we extract the uncertainty information from the error dynamics equation instead of the system dynamics. By reformulating the error dynamics equation as an algebraic equation using auxiliary variables, the need to measure state derivatives in the estimator and controller design is eliminated. Unlike time-delay control (TDC) and uncertainty and disturbance estimator (UDE) methods, we avoid the use of time delay and additional filtering operations to circumvent the noise amplification and oscillations in the control signal. Comparative simulations are provided to verify the effectiveness of the proposed method.