Real-time experimental control of a system in its chaotic and nonchaotic regimes

Current model-independent control techniques are limited, from a practical standpoint, by their dependence on a precontrol learning stage. Here we use a real-time, adaptive, model-independent ~RTAMI! feedback control technique to control an experimental system — a driven magnetoelastic ribbon — in its nonchaotic and chaotic regimes. We show that the RTAMI technique is capable of tracking and stabilizing higher-order unstable periodic orbits. These results demonstrate that the RTAMI technique is practical for on-the-fly ~i.e., no learning stage! control of real-world dynamical systems. @S1063-651X~97!50710-0#