Suboptimal Control of Rigid Body Motion with a Quadratic Cost

In this paper we consider the problem of controlling the rotational motion of a rigid body using three independent control torques. Given a quadratic cost we seek stabilizing state feedback controllers which are suboptimal in the sense that, given a scalar , they guarantee that all motions starting within a specified bounded set result in a cost bounded by . For a special class of cost functions, we present explicit expressions for suboptimal stabilizing controllers yielding a cost arbitrarily close to the infimal cost. For the general case, we present sufficient conditions which guarantee the existence of linear, suboptimal, stabilizing controllers.