Modal Design of LQ Regulators

T. Fujinaka and S. Omatu (Japan)


LQ Regulator, Pole Shifting, Modal Decomposition


The design of linear quadratic regulator with regard to the location of closed-loop poles is considered. There is no dif ficulty in calculating the optimal feedback gain if a specific performance index to be minimized is given. In a practical situation, however, it often requires repeated adjustment of the weighting matrices of the performance index by trial and error, since the closed-loop characteristics correspond ing to a given weighting matrices may not be satisfactory. This paper aims at reducing such difficulty by eliminating too much freedom in the design parameters, while retaining sufficient room for adjustment during the design procedure. We propose an iterative design method for constructing a state feedback gain, where a single mode of the system is altered in each step of the iteration. This helps in keep ing the overall balance in the construction of the feedback gain, avoiding inappropriate choice of weighting matrices or closed-loop poles.

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