Design and Control of an Unmanned Aerial Vehicle for Autonomous Parcel Delivery with Transition from Vertical Take-off to Forward Flight – VertiKUL, a Quadcopter Tailsitter

This paper presents the design and control of VertiKUL, a Vertical Take-Off and Landing (VTOL) transitioning tailsitter Unmanned Aerial Vehicle (UAV), capable of hover flight and forward flight for the application of parcel delivery. In contrast to existing transitioning UAVs, VertiKUL is not controlled by control surfaces, but exclusively by four propellers using differential thrust during hover flight, transition and forward flight. A numerical design method optimising range and payload is developed for initial sizing. A simulation model is implemented in Simulink to evaluate different control strategies before conducting test flights. A unique mid-level control strategy enabling intuitive control of VertiKUL which requires no pilot skills is developed. Fluent transition from hover to forward flight is achieved through an autonomous control strategy. Attitude control based on quaternions instead of Euler-angles is implemented to avoid singularities. The resulting design, VertiKUL, is built and test flown.