Despite extensive research on sliding mode control (SMC) design for quadrotors, the existing approaches suffer from certain limitations. Euler angle-based SMC formulations suffer from poor performance in high-pitch or -roll maneuvers. Quaternion-based SMC approaches have unwinding issues and complex architecture. Coordinate-free methods are slow and only almost globally stable. This paper presents a new six degrees of freedom SMC flight controller to address the above limitations. We use a cascaded architecture with a position controller in the outer loop and a quaternion-based attitude controller in the inner loop. The position controller generates the desired trajectory for the attitude controller using a coordinate-free approach. The quaternion-based attitude controller uses the natural characteristics of the quaternion hypersphere, featuring a simple structure while providing global stability and avoiding unwinding issues. We compare our controller with three other common control methods conducting challenging maneuvers like flip-over and high-speed trajectory tracking in the presence of model uncertainties and disturbances. Our controller consistently outperforms the benchmark approaches with less control effort and actuator saturation, offering highly effective and efficient flight control.

翻译：尽管针对四旋翼飞行器的滑动模态控制（SMC）设计已有广泛研究，但现有方法仍存在一定局限性。基于欧拉角的SMC方法在大俯仰或大滚转机动中性能较差；基于四元数的SMC方法存在展开奇异问题且架构复杂；无坐标方法收敛速度缓慢且仅具有几乎全局稳定性。本文提出一种新型六自由度SMC飞行控制器以解决上述局限性。采用外环位置控制器与内环基于四元数姿态控制器的级联架构：外环位置控制器通过无坐标方法生成姿态控制器所需期望轨迹；内环基于四元数的姿态控制器利用四元数超球面的固有特性，在避免展开奇异问题的同时实现全局稳定性且结构简洁。我们通过翻转让飞及含模型不确定性与扰动的高速轨迹跟踪等挑战性机动，将所提控制器与三种常见控制方法进行对比。实验结果表明，所提控制器在控制能耗与执行器饱和程度方面持续优于基准方法，实现了高效能飞行控制。