  In this paper we address the question how the control of delayed measured
chaotic systems can be improved. Both unmodified OGY control and difference
control can be successfully applied only for a certain range of Lyapunov
numbers depending on the delay time. We show that this limitation can be
overcome by at least two classes of methods, by rhythmic control and by the
memory methods linear predictive logging control (LPLC) and memory difference
control (MDC).
