Abstract
The direct velocity and displacement feedback (DVDFB) is considered for large space structures with collocated sensors and actuators. It has been known that when the gains of the feedback are negative definite, stability of the closed-loop system is preserved under any perturbations in mass, damping, and/or stiffness. That is, DVDFB is a robust stabilizing control law. The main objective of this paper is to show that, moreover, if the gains are appropriately selected, then DVDFB is optimal control for a quadratic performance index. Obtained conditions for DVDFB to be optimal imply that we need to increase the velocity feedback sufficiently when we increase the displacement feedback. To demonstrate effectiveness of the optimal DVDFB, a simulation result is presented for the Engineering Test Satellite VI, the operation of which is supposed to start in 1992.
