Robust tracking controller for multivariable delayed systems with input saturation via composite nonlinear feedback

In this paper, the composite nonlinear feedback (CNF) method for robust tracking control of multivariable time-delayed systems with input saturation is proposed. By constructing an appropriate Lyapunov–Krasovskii functional and using the linear matrix inequality (LMI) technique, the asymptotic tracking criteria is derived in terms of LMI, which can be solved numerically using the LMI^® toolbox of MATLAB. Unlike the previous robust tracking controller design methods, which need restrictive assumptions, less conservative design conditions are obtained using this approach. The proposed CNF-based robust tracking controller improves the transient performance and steady state accuracy simultaneously. Simulation results are included to demonstrate the effectiveness of the proposed method.