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：本文提出了一种提升四旋翼飞行器轨迹跟踪鲁棒性的简洁方法。该方法的核心是一个高增益扰动观测器（HGDO），能够实时提供扰动估计值，这些估计值随后被用于轨迹控制律中以补偿扰动影响。我们给出了理论收敛性结果，表明所提出的HGDO可快速收敛到真实扰动值的可调邻域。我们将扰动估计值与典型的鲁棒轨迹控制器——滑模控制（SMC）相结合，并通过李雅普诺夫稳定性分析证明了轨迹跟踪误差的有界性。此外，本文的稳定性分析可轻易推广至其他基于李雅普诺夫方法的控制器，从而衍生出具有形式化稳定性保证的多种HGDO控制方案。我们通过多种场景下的仿真与实验室实验，在存在外部扰动的情况下对基于HGDO的控制方法进行了评估。结果表明，将HGDO集成至四旋翼轨迹控制器可显著提升存在外部扰动时的轨迹跟踪精度与准确度。