Aerial manipulation has gained interest in completing high-altitude tasks that are challenging for human workers, such as contact inspection and defect detection, etc. Previous research has focused on maintaining static contact points or forces. This letter addresses a more general and dynamic task: simultaneously tracking time-varying contact force in the surface normal direction and motion trajectories on tangential surfaces. We propose a pipeline that includes a contact-aware trajectory planner to generate dynamically feasible trajectories, and a hybrid motion-force controller to track such trajectories. We demonstrate the approach in an aerial calligraphy task using a novel sponge pen design as the end-effector, whose stroke width is proportional to the contact force. Additionally, we develop a touchscreen interface for flexible user input. Experiments show our method can effectively draw diverse letters, achieving an IoU of 0.59 and an end-effector position (force) tracking RMSE of 2.9 cm (0.7 N). Website: https://xiaofeng-guo.github.io/flying-calligrapher/

翻译：空中操作在执行高空作业（如接触式检测与缺陷识别等）方面日益受到关注，这些任务对人类工作者而言颇具挑战。先前研究主要集中于维持静态接触点或接触力。本文探讨一项更为通用且动态的任务：同时跟踪表面法向的时变接触力与切向表面的运动轨迹。我们提出一套流程，包含用于生成动力学可行轨迹的接触感知轨迹规划器，以及用于跟踪此类轨迹的混合运动-力控制器。我们通过一项空中书法任务验证该方法，采用一种新颖的海绵笔设计作为末端执行器，其笔画宽度与接触力成正比。此外，我们开发了触摸屏界面以实现灵活的用户输入。实验表明，所提方法能有效绘制多种字母，达到0.59的交并比（IoU）及末端执行器位置（力）跟踪均方根误差2.9厘米（0.7牛）。项目网站：https://xiaofeng-guo.github.io/flying-calligrapher/