Autopilot design for a tail-controlled missile using LQG/LTR with eigenstructure reassignment

Abstract

This paper demonstrates the effectiveness of LQG/LTR designed controllers for a nonminimum phase plant with lightly damped complex poles. Although this type of plant is troublesome for LQG/LTR, this paper documents the successful design of lateral acceleration controllers for a tail-controlled lifting-body missile. The controller designed for this paper successfully meets minimum rise-time specifications (68% within 200 ms) with minimum overshoot (/spl les/25%). This success is attributed to the use of inner loop feedback of static gains designed to alter the eigenstructure of the plant. Eigenstructure reassignment includes relocation of plant poles and partial reassignment of components of the eigenvectors. Eigenvector component assignment allows the designer the extra latitude of coupling and decoupling modes of the system. Furthermore, eigenstructure reassignment makes use of information contained in available measurements which standard LQG/LTR is incapable of using.