Abstract:

This paper presents a control allocation and thruster quantization method to simultaneously perform station keeping, attitude control, and momentum management of a geostationary Earth orbit (GEO) satellite equipped with two electric thrusters mounted on gimbaled booms, each with four degrees-of-freedom (DOFs). A modified version of a previously-developed model predictive control (MPC) policy is used to generate an optimal body force and torque that is then allocated and quantized before being implemented on the satellite. The novel control allocation method optimally solves for boom gimbal angles and thruster magnitudes that produce a force and torque that best match the force and torque calculated using the MPC policy. The quantization scheme then optimizes the on-off times of each thruster to minimize error in the predicted satellite states due to quantization. Numerical simulation results are presented that illustrate the performance of the proposed control formulation and highlight the fuel consumed due to the individual control allocation and thrust quantization stages.