COMPOSITE DESCRIBING FUNCTION OF SUCCESSIVE NON-LINEAR COMPONENTS IN FEED BACK CONTROL SYSTEMS

Abstract

Recent work by the author on a transformation method for the study of nonlinear components is utilized to evaluate the composite describing function of successive non-linear components in feed-back control systems. Characteristic equations for different values of the non-linearizing parameters are given for commonly encountered non-linear components, in control system practice. Composite describing functions are evaluated in case of a backlash followed by a dead-zone,and also in case of a rate-limiting device followed by a variable gain amplifier. In the latter case, the composite describing function is dependent on the input amplitude and frequency.