Attitude control design for flying boom during air-to-air refuelling

Compared with hose-and-drogue refuelling, flying boom refuelling has attracted increasing interest due to its high flow rates and easy contact operation. Aided by a flying boom attitude controller, the boom operator navigates the flying boom into contact with the receptacle of the receiver aircraft. However, disturbances, including tanker wake and atmospheric turbulence, can disturb the motion of the flying boom. In addition, the boom operator requires that the flying boom has good handling qualities to accomplish aerial boom refuelling. To solve the first challenge, a novel back-stepping control approach - back-stepping control driven by a sliding mode disturbance observer - was adopted for attitude control to improve robustness and performance. To address the second challenge, the command filter, which affects the handling qualities, was designed in the attitude control to protect the flying boom from damage. To achieve the desired handling qualities, a mission-oriented method was implemented to determine the filter parameters. Finally, three manoeuvres - yaw tracking, pitch tracking and attitude hold - were calculated to simulate real aerial boom refuelling. The results demonstrate the proposed attitude controller's effectiveness and robustness.