State Estimation for Dual-Time-Scale Cyber-Physical Systems With Asynchronous Channels and Digital Sensors

This paper investigates the state estimation problem for dual-time-scale cyber-physical systems (DTSCPSs) with asynchronous communication channels operating on slow and fast time scales, where measurement information is obtained from digital sensors with certain resolutions. Aiming to accommodate the limited communication resources and asynchronous data packet transmission for different sensors that collect measurement outputs for slow and fast states, respectively, a special asynchronous encoding-decoding protocol is proposed from sensors to estimators. It should be noticed that sensor resolution is taken into consideration in this paper, which is an essential attribute of digital sensors and characterizes the measurement and data processing accuracy. An ε-dependent Lyapunov function is established and a novel ε-dependent estimator is carried out, which guarantees the estimate error dynamics being exponentially ultimately bounded. Furthermore, ε-dependent criteria are proposed to calculate the estimator gains, which are free of numerical stiffness caused by the DTSP. A simulation example is provided to verify the effectiveness of the proposed methods.