Abstract

Autonomous control greatly reduces the demand on ground-based resources to keep satellites in a constellation and working reliably, which would be nearly impossible to do without such automation. Linear feedback control is primarily used to counter unexpected small perturbations and to maintain generally sub-optimal trajectories. Linearized approximation of the actual non-linear satellite dynamics cannot predict the "non-local" behavior far from the operating point and certainly not the "global" behavior throughout the state space. The objective of this thesis is development of a formation control and station keeping control laws for a constellation of satellites in a circular orbit. It is shown that by utilizing feedback linearization or nonlinear compensation techniques, an efficient nonlinear control design strategy may be implemented that leads to solutions valid for larger set point regulation, perturbations and station keeping problems. To assess the quality of the proposed control scheme, its performance is compared with that of linear pole placement controller and a nonlinear controller designed using potential function method in a number of simulation case studies. Advantages and disadvantages of the proposed nonlinear control technique are also presented for formation control and station keeping