Monitoring the condition of feedback control systems

A condition monitoring scheme for feedback control systems is presented. This scheme is meant for detecting seriously deteriorating conditions of a feedback system, in both transient state and steady state, before instability becomes manifest. It is assumed that the process is disturbed by a random noise with a rational spectrum and by a series of deterministic signals. The frequency characteristics in steady state oscillatory characteristics in transient state are monitored. A transient detector is used to differentiate steady state from transient state. This scheme divides the monitoring task into three subtasks: transient detection, transient monitoring, and steady-state monitoring. Algorithms have been developed for each subtask, and logic rules have been employed to coordinate these algorithms so that they can function correctly to monitor the system in different situations. Simulation experiments demonstrated the promising performance of this monitoring scheme