ATV guidance navigation and control for rendezvous with ISS

The Automated Transfer Vehicle (ATV) is a European cargo transfer vehicle designed to carryout in-orbit replenishment missions to the International Space Station. The ATV first flight is currently planned for 2003. This paper provides a deeper insight into some innovative GNC functions used during the rendezvous operations. Absolute GPS navigation based on PVT filtering. This navigation function provides the absolute position estimation with the accuracy required by the specific Relative GPS processing, while keeping the complexity and size of the processing to a level acceptable with respect to the computer load constraints. Thruster Selection Function: a new algorithm has been developed to provide the optimum selection of the set of thrusters to fire to realize the commanded force/torque vector. An innovative solution has been found to manage saturations, to obtain the maximum available force level while preserving the colinearity of the realized force/torque with respect to the command.