DAMPENING CONTROLLERS VIA A RICCATI EQUATION APPROACH

An algorithm is presented which computes a state feedback for a standa rd linear system which not only stabilizes, but also dampens the close d-loop system dynamics. In other words, a feedback gain matrix is comp uted such that the eigenvalues of the closed-loop state matrix are wit hin the region of the left half-plane where the magnitude of the real part of each eigenvalue is greater than that of the imaginary part. Th is may be accomplished by solving a damped algebraic Riccati equation and a degenerate Riccati equation. The solution to these equations are computed using numerically robust algorithms. Damped Riccati equation s are unusual in that they may be formulated as an invariant subspace problem of a related periodic Hamiltonian system. This periodic Hamilt onian system induces two damped Riccati equations: one with a symmetri c solution and another with a skew-symmetric solution. These two solut ions result in two different state feedbacks, both of which dampen the system dynamics, but produce different closed-loop eigenvalues, thus giving the controller designer greater freedom in choosing a desired f eedback.