Network load minimisation design for dual-rate Internet-based control systems

This study presents a design method for Internet-based control systems in a dual-rate configuration to achieve load minimisation and dynamic performance specifications. It avoids the complexity of large-scale system design by focusing on individual control systems. In the dual-rate configuration, the plant under control is first stabilised by a local controller with a high sampling rate. The remote proportional integral derivative (PID) controller, which regulates the output according to the desirable reference, adopts a low sampling rate to reduce load on the network. The upper bound of the remote PID controller´s sampling time which meets the requirement on control performance is derived and a simple tuning method for the remote PID controller is presented. Simulation and real-time examples are provided for illustration.