DISCRETE-TIME LOOP TRANSFER RECOVERY VIA GENERALIZED SAMPLED-DATA HOLD FUNCTIONS BASED COMPENSATOR

Loop transfer recovery (LTR) techniques are kown to enhance the input or output robustness properties of linear quadratic gaussian (LQG) des igns. One restriction of the existing discrete-time LQG/LTR methods is that they can obtain arbitrarily good recovery only for minimum-phase plants. A number of researchers have attempted to devise new techniqu es to cope with non-minimum-phase plants and have achieved some degree s of success.6-9 Nevertheless, their methods only work for a restricte d class of non-minimum-phase systems. Here, we explore the zero placem ent capability of generalized sampled-data hold functions (GSHF) devel oped in Reference 14 and show that using the arbitrary zero placement capability of GSHF, the discretized plant can always be made minimum-p hase. As a consequence, we are able to achieve discrete-time perfect r ecovery using a GSHF-based compensator irrespective of whether the und erlying continuous-time plant is minimum-phase or not.