Hybrid unmanned aerial vehicles (UAVs) provide an interesting combination of the vertical takeoff and landing (VTOL) capabilities of rotary-wing (RW) and of the efficient forward flight of fixed-wing (FW) vehicles. The employed controllers must be able to handle the highly nonlinear dynamics and changing control authorities resulting from this combination, especially during the transition between the two flight modes. In this paper, a nonlinear model predictive control (MPC) structure is designed and applied to a tiltrotor convertible UAV. Full-flight envelope trajectory tracking and optimal exploitation of the aircraft’s VTOL and FW properties is achieved. A common approach is to design a set of stable controllers for various trim-points in the flight envelope and make use of Gain Scheduling (GS) or controller mixing, in order to select the appropriate control law for a given flight configuration. In this paper, a unified control approach is developed. A nonlinear MPC structure is designed and applied to a tiltrotor convertible UAV whose nonlinear model is derived and presented. Thus, full-flight envelope trajectory tracking and optimal exploitation of the aircraft’s VTOL and FW properties are achieved, without the need for controller switching or scheduling policies. The proposed multi-stage control allocation handles the changing control authorities of the actuators in a continuous manner and efficiently distributes the required control actions between propellers, tilt servos and control-surfaces. The feasibility and performance of this novel control approach are successfully evaluated in real-world flight experiments. Simulation results for comparison with state-of-the-art approaches are presented.

混合动力无人机 (UAV) 将旋翼 (RW) 的垂直起降 (VTOL) 能力与固定翼 (FW) 车辆的高效前飞能力结合在一起。所采用的控制器必须能够处理这种组合导致的高度非线性动态和不断变化的控制权限，尤其是在两种飞行模式之间的转换期间。本文设计了一种非线性模型预测控制（MPC）结构，并将其应用于倾转旋翼可转换无人机。实现了全飞行包线轨迹跟踪和飞机 VTOL 和 FW 特性的优化利用。一种常见的方法是为飞行包线中的各种配平点设计一组稳定的控制器，并利用增益调度 (GS) 或控制器混合，以便为给定的飞行构型选择合适的控制律。在本文中，开发了一种统一的控制方法。设计了一种非线性MPC结构并将其应用于倾转旋翼可转换无人机，其非线性模型被推导和呈现。因此，无需控制器切换或调度策略即可实现全飞行包线轨迹跟踪和飞机 VTOL 和 FW 特性的优化利用。建议的多级控制分配以连续方式处理执行器不断变化的控制权限，并在螺旋桨、倾斜伺服系统和控制面之间有效地分配所需的控制动作。这种新型控制方法的可行性和性能在实际飞行实验中得到了成功评估。