Nonlinear control system response to random signals

IN GENERAL servomechanisms are nonlinear, the linear type being only a special case. Consequently, for a number of years a considerable amount of time has been devoted to the study of nonlinearities in control systems. Until recently these studies have been limited to the analysis of systems with inherent nonlinear characteristics. More recently, however, interest has arisen in control systems using nonlinear characteristics for producing distinctive and desirable features of system behavior.