The use of non-piloted eVTOL aircraft in non-segregated airspace requires reliable and deterministic automatic flight guidance systems for the aircraft to remain predictable to all the users of the airspace and maintain a high level of safety. In this paper we present a 3D trajectory generation module based on clothoid transition segments in the horizontal plane and high order polynomial transition segments in the vertical plane. The expressions of the coefficients of the polynomial are derived offline are used to generate the trajectory online, making the system capable of running in real time without requiring enormous computational power. For the horizontal plane, we focus on the flyby transition, and therefore present a thorough analysis of the flyby geometry and the limitations linked to this geometry and the construct of three-segment trajectory generation around a fixed turn rate. We present feasible solutions for these limitations, and show simulation results for the combined horizontal and vertical plane concepts, allowing the system to generate complex 3D trajectories.

Using electric vertical takeoff and landing (eVTOL) aircraft for urban air mobility requires a high level of maneuverability and tracking accuracy from the flight guidance systems. This can be achieved by constructing a high-order desired trajectory, in order to provide jerk-level feedforward commands and acceleration-level relative kinematics. In this paper, we perform a noise analysis on a trajectory system where relative kinematics are computed numerically, and we show the resulting noise effects. We then present an analytical alternative which improves the noise sensitivity. Additionally, we develop a smoothing strategy for obtaining a high-order parametrization of a trajectory designed with low-order clothoid curves. The methods presented in the paper are tested and validated in closed-loop simulations and through flight tests on a 700 kg medical-evacuation eVTOL aircraft. The results of these tests are presented and discussed.