Hybrid VTOL UAVs, i.e. platforms that combine the vertical take-off, landing, and hovering capability of multirotors with the efficient forward flight of fixed-wing aircraft, have matured significantly over the past decade. By uniting hover agility with long-range, energy-efficient cruise, they unlock missions that neither configuration can serve alone, including infrastructure inspection over large areas, precision agriculture, medical and logistics delivery, and search-and-rescue operations.
Despite these advances, the widespread deployment of hybrid VTOL UAVs remains constrained by the vulnerability of the hover-to-cruise transition to disturbances and actuator degradation, state estimation that deteriorates in GNSS-degraded or -denied conditions, planning frameworks that lack explicit risk awareness and contingency management, and a persistent dependence on human supervision. These limitations stand in the way of safe, certifiable operations beyond visual line of sight (BVLOS), as envisioned by emerging regulatory frameworks such as EASA's Specific Operations Risk Assessment (SORA) and the European U-space ecosystem.
This project outlines the conceptual and technical foundations for safe autonomy of hybrid VTOL UAVs, addressing these limitations through fault-tolerant transition-aware control, resilient multi-sensor state estimation, risk- and contingency-aware planning, and runtime assurance frameworks paving the way towards certifiable autonomy.
PhD Research Project
The objective of this PhD is to contribute to the safe autonomy of hybrid VTOL UAVs by advancing one or more of the following four research pillars:
- Design and implementation of fault-tolerant, transition-aware flight control for hybrid VTOL platforms, ensuring flight envelope protection and graceful degradation under actuator faults, wind gusts, and icing across the full hover-transition-cruise regime.
- Development of resilient state estimation through fusion of heterogeneous sensor modalities (IMU, GNSS, airspeed, vision, LiDAR), providing reliable localization and integrity monitoring in GNSS-degraded or -denied environments.
- Development of risk- and contingency-aware mission planning, including safety-aware path planning over populated areas, emergency landing site selection, geofencing, and reactive avoidance of static and dynamic obstacles.
- Development of runtime assurance and verification frameworks, combining online safety monitoring, formally bounded fallback behaviours, and certification-oriented evidence generation aligned with SORA and U-space requirements, reducing reliance on human supervision.
Validation of the developed systems is planned in controlled lab settings (drone cage, motion capture, hardware-in-the-loop simulation, onboard computing) and in outdoor flight campaigns, with application domains including long-range infrastructure inspection (e.g. pipelines, power lines, wind farms), precision agriculture (e.g. crop monitoring over large fields), logistics and medical delivery, and dual-use scenarios (e.g. maritime patrol and search-and-rescue).
The research is supervised by Prof. Jolan Wauters within the framework of an individual project on safe autonomy of hybrid VTOL UAVs. It offers close collaboration with the RAM division of KU Leuven, university association partners, international research partners, and industry partners.
