CHAOS CONTROL - HOW TO AVOID CHAOS OR TAKE ADVANTAGE OF IT

The purpose of this paper is to review the most interesting control co ncepts developed for chaotic circuits and systems. In most cases the g oal of the control procedure is in converting chaotic behavior into a periodic or constant motion. There also exist specific tasks where cha otic behavior is advantageous-due to extreme sensitivity to changes in initial state it is possible to direct trajectories to targets much f aster than without control. Tracking of specific chaotic trajectories might be useful in communication schemes-where chaos is leed to hide u seful information. The control concepts described include: (i) system parameter variation, (ii) chaotic oscillation absorber, (iii) entrainm ent, (iv) error feedback methods, (v) time-delayed feedback, and (vi) methods for stabilizing unstable periodic orbits: occasional proportio nal feedback and sampled input waveform methods. Potential strengths a nd weaknesses of these methods are discussed.