Incremental nonlinear control allocation for a tailless aircraft with innovative control effectors

Conventional linear control allocation (LCA) methods fail to provide satisfactory per- formance in ight control systems (FCS) for aircraft with highly nonlinear and coupled control effector suites, especially for tailless aircraft with strong interactions between con- trol effectors. This is due to the inability of linear effector models to capture nonlinear and coupled control forces and moments. This paper implements an incremental nonlin- ear control allocation (INCA) approach, which can capture nonlinearities and interactions of control effectors while being solvable with simple and computationally effcient linear control allocation algorithms. This makes INCA suitable for real-time control allocation in FCS. This incremental reformulation of the control allocation problem is based on a Jacobian model of the control eFFectors, and relies on angular acceleration measurements to reduce model dependency. In addition, it operates based on real-time measurements of the actuator positions, which mitigates typical problems related to couplings between control allocators and actuator dynamics. In this paper, LCA- and INCA-based nonlinear FCS are designed for the Innovative Control Effectors (ICE) aircraft, a highly maneuver- able tailless aircraft with 13 highly nonlinear, interacting and axis-coupled control effectors. Real-time simulation results show that INCA dramatically improves tracking and control allocation performance, thus improving maneuverability and exploiting the full potential of innovative control effector suites.