Analysis of the technique of robust eigenstructure assignment with application to aircraft control

Given the linear state-space representation of a dynamic system, a method for computing allowable eigenvector subspaces using singular value decomposition for both real and complex eigenvalues is illustrated. Once these spaces have been determined, it is possible to assign the eigenvectors in two ways: one which performs desirable weightings of the system states for each mode permitting system decoupling, and the second which assigns eigenvectors iteratively, to make the corresponding eigenvalues as insensitive to perturbations inthe system matrices as possible. A computational procedure for each of these techniques is described. The work is illustrated using the stability augmentation system control design problem for the lateral motion model of a nonlinear aircraft system. The modal requirements for this problem are well known, and this enables acomparison of the two methods to be made.