SYSTEM DEGRADATION FACTOR FOR NETWORKED CONTROL SYSTEMS

Abstract

The main differences between networked control systems (NCS) and classical directly wired, (non-NCS) are phenomena such as packet dropouts and packet delays. In general, dynamical properties of NCS and non-NCS are different and understood as degradation of the system. Mainly, the considerations concern on the estimating of the degradation degree of the NCS with linear time-invariant components (plant, actuator, sensor, controller) in respect to non-NCS realization of the same system. It is shown that the problem can be reduced to analysis of the nonstationarity degree of NCS. The degradation degree is calculated in frequency domain using SVD-DFT transformation of system operator defined on finite time horizon. The method enables to make a quantitative comparison of different control strategies, under given probability of packet dropouts, time delays, etc. Theoretical considerations of computational algorithms are complemented with numerical examples.