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模控制（SMC）设计已进行了广泛研究，但现有方法仍存在一定局限性。基于欧拉角的SMC方案在高俯仰或高滚转机动中表现不佳；基于四元数的SMC方法存在解旋问题且结构复杂；无坐标方法响应速度慢且仅具备近似全局稳定性。本文提出一种新型六自由度SMC飞行控制器以解决上述问题。我们采用级联架构，外环为位置控制器，内环为基于四元数的姿态控制器。位置控制器通过无坐标方法为姿态控制器生成期望轨迹。基于四元数的姿态控制器利用四元数超球面的自然特性，在实现全局稳定性并避免解旋问题的同时保持结构简洁。我们在模型不确定性和干扰条件下，通过翻转机动与高速轨迹跟踪等挑战性动作，将本控制器与另外三种常用控制方法进行对比。实验表明，本控制器在控制能耗和执行器饱和方面均优于基准方法，实现了高效且鲁棒的飞行控制。