Robust Control Design for a Networked Cascade Control System based on Augmented matrix and in presence of Network Delay

In this paper, stability of a group of networked cascade control systems based on a new continuous-time model is investigated and H∞ state feedback controllers considering H∞ norm bounded constraint are designed in order to attenuate external disturbances. The main objective of this research is to simplify stability analysis and provide the possibility of considering different configurations based on a continuous-time state-space model for these systems.To this aim, here it is assumed that data transformation between the secondary controller and the actuator is performed through a communication network. Using communication networks would result in some imperfections such as communication delay and data packet loss which are considered in the modelling of the system. Then, the state-space equations of the systems are converted to an equivalent augmented state-space equation. Stability of the system is analyzed based on the Lyapunov-Krasovskii theorem and using free weighting matrix method and controller gains as well as maximum allowable delay bound are computed. Simulation results confirm the validity of the proposed method.