Fuzzy Immune Self-Regulating PID Control Based on Modified Smith Predictor for Networked Control Systems

Network delay is the main factor that deteriorates the performance of networked control systems (NCS). In order to effectively restrain the impact of network delay on NCS, Aiming to time-variant, random and uncertain network delay, controlled plant might be time-variant or nonlinear, a new approach is proposed that modified Smith predictor combined with fuzzy immune PID control for NCS, Because modified Smith predictor does not include network delay, therefore, it is no need for measuring on-line, identifying or estimating network delays, it is applicable to some occasions that network delays are time-variant, random and uncertain, larger than one, even tens of sampling periods. Based on CSMA/CD (Ethernet) and CSMA/AMP (CAN bus), the simulation results show that the proposed method has the adaptability, strong robustness and satisfactory control performance requirement.