Design of low-order compensators using parameter optimization (Q2265973)

An LQG synthesis algorithm is presented that optimizes the parameters of a multi-input, multi-output compensator for a linear time-invariant plant, where the designer specifies the order and the structure of the compensator. An instructive way to use the algorithm is to start the full-order LQG compensator in minimum-realization modal form, and then omit the more rapidly-damped modes with small residues. The reduced-order compensator is then optimized using the present algorithm. As an example, compensators of order 4, 3, 2 and 1 were designed for a seventh-order model of an airplane with two controls, two outputs, two disturbances and three measurements. Surprisingly little performance is lost by using these lower-order compensators.