STABILIZATION OF NONLINEAR LARGE-SCALE SYSTEMS BY DITHERS

The injection of high-frequency signals, commonly called dithers: into a nonlinear large-scale system may improve its performance. Stability of the dithered large-scale system is related to that of its correspo nding model-the smoothed large-scale system. The dithers' amplitudes, but not their frequencies, affect the sectors of nonlinearities. The i mportance of dithers' frequencies is found in their effect on the devi ation of the smoothed large-scale system from the dithered large-scale system, and the deviation can be improved as the frequencies of dithe rs increase. Dithers of sufficiently high frequencies may result in ou tputs of the smoothed large-scale system and of the dithered large-sca le system as close as desired. This fact enables a rigorous prediction of stability of the dithered large-scale system by establishing that of its corresponding smoothed large-scale system. The main characteris tic of this work is that an algorithm is proposed to find the lower bo und of each dither's amplitude for stabilizing the nonlinear large-sca le system.