This paper presents a simple method to boost the robustness of quadrotors in trajectory tracking. The presented method features a high-gain disturbance observer (HGDO) that provides disturbance estimates in real-time. The estimates are then used in a trajectory control law to compensate for disturbance effects. We present theoretical convergence results showing that the proposed HGDO can quickly converge to an adjustable neighborhood of actual disturbance values. We will then integrate the disturbance estimates with a typical robust trajectory controller, namely sliding mode control (SMC), and present Lyapunov stability analysis to establish the boundedness of trajectory tracking errors. However, our stability analysis can be easily extended to other Lyapunov-based controllers to develop different HGDO-based controllers with formal stability guarantees. We evaluate the proposed HGDO-based control method using both simulation and laboratory experiments in various scenarios and in the presence of external disturbances. Our results indicate that the addition of HGDO to a quadrotor trajectory controller can significantly improve the accuracy and precision of trajectory tracking in the presence of external disturbances.

翻译：本文提出一种增强四旋翼飞行器轨迹跟踪鲁棒性的简单方法。该方法的核心是采用高增益扰动观测器（HGDO）实时提供扰动估计值，并将估计值用于轨迹控制律中以补偿扰动效应。我们给出了理论收敛性结果，证明所提出的HGDO能够快速收敛到实际扰动值的可调节邻域内。随后将扰动估计值与典型的鲁棒轨迹控制器（即滑模控制，SMC）相结合，并通过李雅普诺夫稳定性分析建立了轨迹跟踪误差的有界性。然而，我们的稳定性分析可轻松扩展至其他基于李雅普诺夫的控制器，从而开发出具有形式化稳定性保证的不同HGDO控制器。我们通过仿真与实验室实验，在多种场景及外部扰动存在条件下评估了所提出的HGDO控制方法。结果表明，将HGDO加入四旋翼飞行器轨迹控制器后，在存在外部扰动的情况下显著提升了轨迹跟踪的准确度与精度。