Attitude Determination and Control System Design for a 6U CubeSat for Proximity Operations and Rendezvous

Abstract

The work presented in this paper focuses on the design of an attitude determination and control subsystem (ADCS) for a proximity operation and imaging satellite mission. The ARAPAIMA (Application for Resident Space Object Proximity Analysis and IMAging) mission is carried out by a 6 U CubeSat class satellite equipped with a warm gas propulsion system. The propulsion system comprises an orbital maneuvering thruster which produces 100 mN and a set of 16 reaction control system (RCS) thrusters, of 25 mN each, installed in pairs that generate torques about each of the satellite body axes. The thrust of the RCS thrusters can be modulated over the entire range in steps of 1% due to the rapid solenoid valve actuation. The requirement of the control system is to provide pointing control accuracy of 1 arcmin at 3 σ in the desired imaging direction. The ADCS employs two control laws. One control law, for large angle maneuvers, implements eigenaxis maneuvering and the other, for accurate pointing, is implemented with PID controllers about each body axis. Simulations performed for tracking the resident space object flying in a circular orbit of 500 km altitude from a relative orbit of 250 m are used to test the performance of the ADCS. A comparison between a “traditional” ADCS system with reaction wheels and RCS thrusters for their off-loading, and a system with only RCS thrusters has been performed. The accuracy of the pointing is comparable, the pointing performance as well as the propellant usage for both options are further discussed in the paper. The integration of both controllers within the ADCS and the switching are also discussed.