Adaptive Control and Control Allocation for Spacecraft Formation Flying under Perturbations, Uncertainies, and Faults

Spacecraft formation flying has been identified as an enabling technology. Researchers are focusing lots of efforts towards the development of autonomous control algorithms. Specifically, control laws are responsible for actuating the thrusters of the chaser spacecraft such that a relative desired trajectory is kept between the chaser and the target spacecraft. This research addresses fault tolerant control laws for spacecraft formation flying such that the chaser can accurately track a desired relative trajectory regardless of thruster faults, dynamical uncertainties, and perturbations. A controller based on simple adaptive control theory (SAC) is tested and compared to three other control laws in numerical simulation. All control laws are tested for three types of actuator failures: loss of effectiveness, stuck actuators, and total failure. Moreover, SAC is implemented for an over actuated system. Two control allocation algorithms based on optimization techniques are used to distribute the control signals among the healthier actuators.