A smooth control allocation method for a distributed electric propulsion VTOL aircraft test platform

Distributed electronic propulsion (DEP) aircraft with vertical take-off and landing (VTOL) ability mostly equipped with multiple redundant tiltable propulsors, which are used to provide not only thrusts, but also control torque in all flight mode. The features make the control allocation problem of these aircraft both complex and important. Therefore, this paper proposes: (i) a prototype platform for DEP VTOL aircraft that allows researchers to design and analyse control allocation strategies, and (ii) a uniform hierarchical control allocation method that can be adapted to both MC and FW modes. The platform contains ten fully actuated thrusters, which are distributed in the scaled geometry of a typical DEP-VTOL aircraft. The proposed control allocation strategy uses hierarchical structure to avoid high-dimensional matrix operations for the redundant actuators. The additional constraints on the thrust and tilt angles of the actuators are addressed by adopting cascade generalized inversion (CGI) to force decompensation (FD)-based methods by a coordinate transformation. A novel smooth strategy through Schur Complement is also presented to achieve steady and smooth transition from MC to FW mode. Finally, the proposed method is implemented in the authors' novel platform in both simulations and flight experiments to demonstrate its effectiveness and smoothness.