A survey on passive tolerant control and active predictive control for NCSs with time delays and packet loss

Networked control systems (NCSs) exhibit advantages in distributed architecture and data-sharing capabilities. However, the integration of communication networks may introduce communication constraints such as time delays and packet loss. Therefore, the design of appropriate controllers to ensure high reliability and stability has attracted significant attention. This paper systematically reviews recent advances in addressing communication delays and packet loss in NCSs, and summarises design features of existing controllers along with stability analysis methods for different time domains. Based on this analysis, control methods are categorised into two distinct classes according to their strategies for handling communication constraints: one category encompasses passive tolerant control methods designed to accommodate bounded network imperfections, while the other category involves active predictive control frameworks that preemptively compensate for communication impacts. Both approaches demonstrate notable advantages in reducing system conservatism, yet practical applications still face certain limitations. Future research must prioritise addressing complex network constraints, advancing nonlinear system modelling, and establishing stability theory for deep learning frameworks, thereby comprehensively enhancing the adaptability of NCSs in complex environments.