MONITORING DEVICE FOR CHARACTERISTICS OF CONTROL SYSTEM

摘要

PURPOSE:To detect early the abnormality of a control system by monitoring the characteristics of the control system including the nonlinear characteristics based on the noise components of both controlled variable and manipulated variable. CONSTITUTION:Both input and output signals of a control system to be monitored are sampled at a signal input part 2 and the 1st-4th statistic moments of the noise components included in the observed value of the controlled variable serving as the input signal of the control system and that of the manipulated variable serving as the output signal of the control system are calculated by a monitor index calculating part 3. Thus the standard deviation ratio G of the input signal, the distortion degree S of an amplitude distribution of the output signal and the critosis F are obtained in the form of the monitor index I. This index I is monitored momentarily. When the change is detected to the value IN of a monitor index 5, a state deciding part 4 decides the state of change of the linear characteristics by the comparison with a reference variation pattern that is prepared in response to the change of the nonlinear characteristics. Then the result of decision obtained from the part 4 is displayed at an alarm display part 6.