Energy Optimal Control Allocation for INDI Controlled Transition Aircraft

View Video Presentation: https://doi.org/10.2514/6.2021-1457.vid Existing control allocation approaches usually minimize an L1 or L2 norm of the input vector that is loosely related to the thrust produced or the aerodynamic drag. This paper proposes a novel incremental control allocation method that directly minimizes the power required. The cost functional is derived and the control allocation procedure presented. The proposed control allocation is particularly advantageous in the case of a transition aircraft using an incremental nonlinear dynamic inversion (INDI) controller. In this case, the minimum-energy incremental control allocation allows to solve the trim problem that generally arises for transition aircraft. The trade-off between using aerodynamic lift versus vertical thrust is solved naturally by including the incremental attitude commands from the outer INDI loop as virtual inputs in the control allocation. The proposed method therefore solves the minimum-energy trim and allocation problem for a transition aircraft without the use of flight mode switching or blending functions throughout all flight regimes. Nonlinear simulations of an over-actuated transition aircraft are presented that showcase the inherent energy-optimal trim and control allocation during different maneuvers.