DESCRIBING FUNCTION FOR SUCCESSIVE NON-LINEARITlES

Abstract

Composite describing function for two consecutive non-linearities in a control system are evaluated by two methods. The first method combines the effects of both the non-linearities into a single non-linear characteristic and the describing function is obtained by integration. The second method makes use of equal area concept for the output waveform. Two examples one with backlash followed by deadzone and the other backlash followed by deadzone and limited proportionality are illustrated. The results obtained by both the methods are compared with those obtained by conventional methods. The simplicity in arriving at the formula for the composite describing function by both the methods is of special importance.Describing function for successive non-linearities of similar characteristics are also discussed.