On the robust stabilization of sampled-data control systems with a sector nonlinearity

In this paper, we have described an evaluation method of the robust stability of sampled-data control systems with one time-invariant nonlinear element in the forward path and the possibility of the robust stabilization of this type of control system. Stability theory involves the expansion of Popov's criterion to discrete-time systems and judgement by explicitly expressing criterion in the frequency domain. The nonlinear characteristics that should be considered need not be specially memoryless, but the summation of trapezoidal areas determined by the path of sampling paints should be non-negative. In order to verify the above theory. we considered a broken line nonlinearity as a numerical example and the deterioration in the stability of nonlinear sampled-data control systems caused by an increase in the sampling period. Improvement in the robust stability is possible not only by the phase lead effect by a linear compensator. but also by a slight gain change within the sector. Copyright (C) 1998 IFAC.