MPC Flight Control for a Tilt-Rotor VTOL Aircraft

• Published in: IEEE transactions on aerospace and electronic systems Vol. 57; no. 4; pp. 2395 - 2409
• Main Authors: Bauersfeld, L., Spannagl, L., Ducard, G., Onder, C.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Actuators; Aerospace control; Aircraft; Aircraft configurations; Aircraft control; Algorithms; Atmospheric modeling; Attitude (inclination); Attitude control; Control allocation; Control systems; Engineering Sciences; Fixed wings; Flight control; Forward flight; hybrid systems; Military helicopters; model predictive control (MPC); Nonlinear control; PID control; Predictive control; Propellers; Proportional integral derivative; Resource management; Rotors; Tilt rotor aircraft; tilt-rotor vertical takeoff and landing (VTOL) aircraft; unmanned aerial vehicles (UAV); Vertical takeoff aircraft; MPC; tilt-rotor UAV; VTOL UAV; Flight control
• ISSN: 0018-9251; 1557-9603
• DOI: 10.1109/TAES.2021.3061819

This article presents a model predictive control (MPC) controller and its novel application to a hybrid tilt-quadrotor fixed-wing aircraft, which combines vertical takeoff and landing (VTOL) capabilities with high-speed forward flight. The developed MPC controller takes a velocity command from the pilot and then computes optimal attitude setpoints and propeller-tilt angles that are supplied to a fast inner attitude controller. A control allocation algorithm then maps the output of the inner attitude loop to actuator commands. The proposed MPC and control allocation of this article constitute a unified nonlinear control approach for tilt-rotor VTOL aircraft, valid in all flight modes and transitions in between. The whole approach is verified both in simulations and in real-world outdoor experiments with a remote controlled VTOL aircraft transitioning from hover to high speed and vice versa in a stable and controlled manner. Results show superior performance compared to the common binary-switch transition strategy between multicopter flight mode and the fixed-wing flight mode. The MPC controller also consistently performs better than a previously developed fused-PID control architecture in our tests.