ANALYSIS OF SELF-SUSTAINED OSCILLATIONS IN DIGITAL CONTROL SYSTEMS——THE DISCRETE DESCRIBING FUNCTION METHOD AND ITS APPLICATION

The discrete describing function method for nonlinear sampled-data systems is introduced in this paper.The discrete describing function(DDF)for the nonlinearity caused by amplitude quantization is analysed by using the discrete Fourier transform,The result obtained in this paper is clear and simple and can easily be used in thedesign of digital control systems.