In this paper, we present an autonomous flight controller for a quadcopter with thrust vectoring capabilities. This UAV falls in the category of multirotors with tilt-motion enabled rotors. Since the vehicle considered is over-actuated in nature, the dynamics and control allocation have to be analysed carefully. Moreover, the possibility of hovering at large attitude maneuvers of this novel vehicle requires singularity-free attitude control. Hence, quaternion state feedback is utilized to compute the control commands for the UAV motors while avoiding the gimbal lock condition experienced by Euler angle based controllers. The quaternion implementation also reduces the overall complexity of state estimation due to absence of trigonometric parameters. The quadcopter dynamic model and state space is utilized to design the attitude controller and control allocation for the UAV. The control allocation, in particular, is derived by linearizing the system about hover condition. This mathematical method renders the control allocation more accurate than existing approaches. Lyapunov stability analysis of the attitude controller is shown to prove global stability. The quaternion feedback attitude controller is commanded by an outer position controller loop which generates rotor-tilt and desired quaternions commands for the system. The performance of the UAV is evaluated by numerical simulations for tracking attitude step commands and for following a way-point navigation mission.

中文翻译：

---

基于四元数反馈的推力矢量旋翼四旋翼无人机自主控制

在本文中，我们提出了一种用于具有推力矢量功能的四轴飞行器的自主飞行控制器。这种无人机属于具有倾斜运动功能的旋翼的多旋翼飞机。由于所考虑的车辆本质上是过度驱动的，因此必须仔细分析动力学和控制分配。此外，这种新型飞行器在大姿态机动下悬停的可能性需要无奇异点姿态控制。因此，利用四元数状态反馈来计算无人机电机的控制命令，同时避免基于欧拉角的控制器遇到的万向节锁定条件。由于缺少三角参数，四元数实现还降低了状态估计的整体复杂性。利用四轴飞行器动力学模型和状态空间来设计无人机的姿态控制器和控制分配。特别地，控制分配是通过将系统关于悬停条件线性化而导出的。这种数学方法使控制分配比现有方法更准确。姿态控制器的李雅普诺夫稳定性分析证明了全局稳定性。四元数反馈姿态控制器由外部位置控制器回路控制，该回路为系统生成转子倾斜和所需的四元数命令。无人机的性能是通过数值模拟来评估的，用于跟踪姿态阶跃命令和跟踪航路点导航任务。这种数学方法使控制分配比现有方法更准确。姿态控制器的李雅普诺夫稳定性分析证明了全局稳定性。四元数反馈姿态控制器由外部位置控制器回路控制，该回路为系统生成转子倾斜和所需的四元数命令。无人机的性能是通过数值模拟来评估的，用于跟踪姿态阶跃命令和跟踪航路点导航任务。这种数学方法使控制分配比现有方法更准确。姿态控制器的李雅普诺夫稳定性分析证明了全局稳定性。四元数反馈姿态控制器由外部位置控制器回路控制，该回路为系统生成转子倾斜和所需的四元数命令。无人机的性能是通过数值模拟来评估的，用于跟踪姿态阶跃命令和跟踪航路点导航任务。四元数反馈姿态控制器由外部位置控制器回路控制，该回路为系统生成转子倾斜和所需的四元数命令。无人机的性能是通过数值模拟来评估的，用于跟踪姿态阶跃命令和跟踪航路点导航任务。四元数反馈姿态控制器由外部位置控制器回路控制，该回路为系统生成转子倾斜和所需的四元数命令。无人机的性能是通过数值模拟来评估的，用于跟踪姿态阶跃命令和跟踪航路点导航任务。