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Demonstrators and research projects about electric aircraft taxi systems testify the current interest in low- or zero-emission ground propulsion technologies to lower the overall fuel consumption and emissions of commercial flights. Electric motors fitted in the main landing gears are one of the most promising layouts for these systems especially for narrow-body commercial aircraft. From a control theory point of view, the aircraft on ground becomes an over-actuated plant through adoption of this technology, i.e. a commanded ground trajectory can be reached through different combinations of actuator efforts. A strategy is required to choose the most suitable of these combinations in order to reach the best efficiency. This work aims to investigate a strategy for an optimal control allocation during path-following of prescribed ground trajectories.

A number of promising technologies to perform ground movements without main engines are currently being researched. Notably, onboard ground propulsion systems have been proposed featuring electric motors in the landing gear. While such on-board systems will help save fuel and avoid emissions while on ground, they add significant weight to the aircraft, which has an impact on the performances in flight. A tool to assess the global benefits in terms of fuel consumption and emissions is presented in this work. A concept of an aircraft-integrated ground propulsion system is firstly considered and its performances and weights are determined, assuming the Auxiliary Power Unit or a zero-emission device like a fuel-cell as power source for the system. Afterwards, a model of the propulsion system integrated into an object-oriented, mid-sized aircraft model is generated, capable of precisely simulating a whole aircraft mission.