Rigid Spacecraft Formations Actuated by Electric Thrusters with One-Bit Resolution

Abstract

In this paper we investigate a formation control problem for two space vehicles in general multibody regimes. The objective is to accurately regulate the distance between the vehicles, as well as the orientation of the overall formation to a desired, rigid configuration, under tight tolerances. The propulsion mechanism of each spacecraft is given by a collection of low thrust electric thrusters. We show that the formation control problem is solvable using constant thrust electric actuators requiring only one bit of resolution, overcoming the problem of actuator resolution. The control law we propose is hybrid, and it coordinates the sequence of on-off switches of the thrusters so as to achieve the control objective and, at the same time, avoid sliding modes.