On Discrete-Time Loop Transfer Recovery

The purpose of this paper is to study what happens when the discrete-time loop transfer recovery (LTR) procedure is applied to nonminimum phase (NMP) plants. Explicit expressions are given for the asymptotic behavior of the resulting sensitivity function and loop transfer function. Both the negligible computation time and significant computation time cases are treated. These results yield a better understanding of the mechanism of the discrete-time loop transfer recovery procedure and the design limitations due to NMP zeros and computation time delays.