The presence of fuel slosh dynamics in a spacecraft system during a maneuver leads to attitude control system (ACS) performance degradation resulting in attitude tracking errors and instability. The dangers of fuel sloshing become more significant with close proximity operations. This paper conducts a comparative study of different optimal control techniques as well as a novel application of a model reference artificial immune system (MRAIS) adaptive controller. A linearized model of a realistic spacecraft dynamic model incorporating fuel slosh is derived using a mass-spring analogy. Simulations with both the linearized model and the full nonlinear equations of motion are performed to achieve the control objective: to suppress the fuel slosh dynamics while obtaining the desired attitude. A performance index quantifies the performance of each ACS design. The MRAIS is proven robust and capable of suppressing fuel slosh even in the presence of system failures and disturbances
