Practical law of robust control for takeoff and landing phases of eVTOL vehicle

Abstract This paper presents the development of a robust control strategy for the take-off, hovering, and landing phases of an electric Vertical Take-Off and Landing (eVTOL) vehicle. Controlling such vehicles is particularly challenging due to the nonlinear nature of their dynamics and the variations in flight conditions. To address these challenges, this work proposes the use of a Singular Value Decomposition (SVD)-guided Linear Quadratic Regulator with output feedback (LQRy), synthesized on an augmented plant with target zeros and combined with a Gain Scheduling strategy. The LQRy controller is designed for multiple linearized operating points within the flight envelope, while the Gain-Scheduling technique ensures smooth transitions between the different operational conditions encountered in this envelope. The effectiveness of the proposed controller is assessed through frequency-domain robustness analysis, considering uncertainties in the inertia matrix within the linear model, and, finally, through nonlinear simulations. The results demonstrate that the proposed approach enables stable flight, ensuring effective disturbance rejection and consistent performance under different operating conditions. For the linear model, the results show that the overshoot, Steady-state time, and rise time requirements are satisfied according to the performance criteria established in this work. For the nonlinear model, it can be observed that the altitude response achieved 0% overshoot during both takeoff and landing, with rise times of 1.63 s and 1.73 s and steady-state time of 2.57 s a