STUDY ON THE CONGESTION CONTROLLER FOR TIME-DELAY NETWORKED CONTROL SYSTEMS WITH EXTERNAL DISTURBANCES

A successive approximation approach (SAA) is developed to obtain a new congestion controller for the singularly perturbed time-delay networked control systems affected by external disturbances. Based on the slow-fast decomposition theory of singular perturbations, the system is first decomposed into a fast non-delay subsystem and a slow time-delay subsystem with disturbances. Then, the perturbation approach is proposed to solve the slow-time scale time-delay optimal control problem, and the feedforward compensation technique is used to reject the external disturbances. We obtain t he conditions of existence and uniqueness of the feedforward and feedback composite control (FFCC) law. The FFCC law consists of linear analytic functions and a time-delay compensation term which is a series sum of adjoint vectors. The linear analytic functions can be found by solving a Riccati matrix equation and a Sylvester equation respectively. The compensation term can be approximately obtained by an iterative formula of adjoint vector equations. A reduced-order disturbance observer is constructed to make the FFCC law physically realizable. Numerical examples are presented to illustrate the effectiveness and robustness of the proposed design approach.