Attitude Control of an Underactuated Planar Multibody System Using Momentum Preserving Internal Torques

In the last few years interest in versatile reconfigurable arrays for space applications has been growing and several concepts tailored for different mission needs have been proposed. Nevertheless, a compelling application that justifies their higher cost and complexity with respect to conventional systemshas not yet been found. Here a novel approach to the design of an Attitude Control System (ACS) for small reconfigurable spacecraft is proposed. It shall exploit momentum-preserving internal torques generated by the modules of the multibody array rotating relative to each other. The goal is to achieve better performance in efficiency, accuracy and robustness with respect to state-of-the-art ACSs, which is a bottleneck of small spacecraft technology. This paper investigates the characteristic behaviour of a planar multibody array whose attitude is controlled using internal joint torques. To do this, relevant reorientation trajectories are shown and discussed. With respect to previous work in the field, optimal attitude control trajectories that take into account module impingement are discussed and the dynamics of momentum-preserving manoeuvres is explained in detail from both physical and mathematical points of view. The results demonstrate that further development of the concept is desirable.