Dynamic Inversion-Based Control Concept for Transformational Tilt-Wing eVTOLs

Transformational electric vertical take-off and landing (eVTOL) vehicles, including tiltwings, have (re)gained popularity over the past decade owing to their advantages of efficient wing-borne cruise flight and reduced requirements on ground-based infrastructure. They promise a new mode of transportation for fast and versatile, short-to-medium-haul on-demand connections. However, they come at the cost of complex mechanics, flight dynamics, and aerodynamics. Among these factors, the different flight regimes and the transition between them make the control system design challenging. Ideally, a flight control system provides means for pilot interaction, autoflight functions, robustness to disturbances, and failure mitigation. The different flight regimes with distinct flight dynamics in a single vehicle motivate a holistic approach. So far, no control approach has prevailed, which raises the question of how to design a control concept that satisfies the above requirements for the full flight envelope. To solve this problem, we derive a generalized representation for transformational eVTOLs and propose a flight control approach for this system, consisting of a dynamic-inversion-based angular rate and velocity control law. Moreover, combining these control functions with optimization-based control allocation is motivated and presented. Finally, the concept is applied to a tandem tilt-wing configuration and analyzed. Results suggest the practicability of the proposed control approach