Target feedback loop/loop transfer recovery (TFL/LTR) robust control design procedures

Target feedback loop/loop transfer recovery (TFL/LTR) is introduced. It represents a general class of robust controller design procedures which are carried out in two sequential steps, namely, TFL design and LTR. several different compensator structures are considered for TFL/LTR designs. The standard linear quadratic Gaussian/loop transfer recovery (LQG/LTR) method becomes a particular type of TFL/LTR procedure, as it involves specific TFL designs and LTR schemes for one particular controller structure. Target feedback loop designs superior to those of LQG/LTR are presented. These use the regulators termed amplified linear quadratic regulator, linear Lyapunov regulator and their dual filters, gain-scaled Kalman filter and Lyapunov filter. A detailed theoretical treatment of these regulators and filters is given. Proofs are furnished for their nominal stability and the outstanding guaranteed stability margins. In addition, some techniques of singular value matching are developed for the purpose of loop shaping. Loop transfer recovery for different controller structures is discussed, and the advantages of the new structures are highlighted