A NEW TOOL FOR THE ANALYSIS OF MODAL CONTROL LAWS - THE POLE ATTRACTORS

In the design of modal control laws, particular attention must be devoted to the choice of the closed-loop eigenvalues. In the output feedback case, this choice become more and more crucial as the degrees of freedom appearing in the control design are decreasing. Then, the assignment of right eigenvectors often induces weakly observable poles. The reluctance of the feedback to move away these poles can be represented by some attracting zones of the complex plane called "pole attractors." In this note, the pole attractors are geometrically defined and their "attractivity" is quantified. The usefulness of such a concept for synthesizing modal control laws is illustrated on a realistic aircraft autopilot design.