Amplitude dependent stability analysis for non-linear sampled-data control systems

This paper analyzes the amplitude dependent behavior of nonlinear sampled-data control systems in a frequency domain. We apply the robust stability condition for nonlinear discrete-time feedback systems (which was derived in our previous papers) to a sampled-data control system containing a single nonlinear element in the forward path. In addition, we derive an instability condition for that type of nonlinear feedback system. By considering restricted areas (sectors) in the nonlinear characteristic, we can accurately predict and estimate the existence of a sustained oscillation whether it is periodic or not. Two ways of stabilizing nonlinear sampled-data control systems will be also examined.