Asymptotic recovery for discrete-time systems

An asymptotic recovery design procedure is proposed for square, discrete-time, linear, time-invariant multivariable systems, which allows a state-feedback design to be approximately recovered by a dynamic output feedback scheme. Both the case of negligible processing time (compared to the sampling interval) and of significant processing time are discussed. In the former case, it is possible to obtain perfect recovery if the plant is minimum-phase and has the smallest possible number of zeros at infinity. In other cases good recovery is frequently possible. New conditions are found which ensure that the return-ratio being recovered exhibits good robustness properties.