This paper introduces and investigates several methods of filtering and delay synchronization in incremental control law structures. It is shown that proper filter and delay synchronization is of great importance for both the performance and stability of the control laws. It is derived how to synthesize complementary filters in case of sensor dynamics, sensor delays and internal control law filtering such as roll-off filters and notch filters. The complementary filters are compared to common synchronization approaches previously applied in incremental control laws. It is shown that the proposed methods are beneficial for Multiple Input Multiple Output (MIMO) systems in case that different delays and filtering is present in the different measurement signals. In case of strongly coupled input effectiveness, the synchronization on the actuator feedback may become even unstable, where the complementary filter approach recovers the design closed-loop behavior. In addition, it is derived how to initialize the complementary filters for a transient-free engagement in non-steady-state conditions. The results are compared in simulation with a roll rate control law for a fixed wing aircraft.

This paper presents a mission data-handling algorithm that provides a data link interface between a flight control computer (FCC) and a ground control station (GCS) using the protocol standard STANAG 4586, AEP-84 Volume II. A subset of defined messages is used for the transmission of mission and area definition data. Functions for decoding uplink messages, processing received data, and encoding downlink messages are developed. Due to a modular software architecture, these functions can be used both for the onboard FCC, as well as for the GCS using additional logic, to invert the transmission direction. Furthermore, high level consistency and validation checks are performed on the transmitted data before forwarding the mission to the flight guidance functions. Successful transmission of mission and area data between the FCC and the GCS is performed using a high-fidelity model-in-the-loop simulation of a demo mission for a medical evacuation eVTOL aircraft.

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.