Collaborative robots require effective human intention estimation to safely and smoothly work with humans in less structured tasks such as industrial assembly, where human intention continuously changes. We propose the concept of intention tracking and introduce a collaborative robot system that concurrently tracks intentions at hierarchical levels. The high-level intention is tracked to estimate human's interaction pattern and enable robot to (1) avoid collision with human to minimize interruption and (2) assist human to correct failure. The low-level intention estimate provides robot with task-related information. We implement the system on a UR5e robot and demonstrate robust, seamless and ergonomic human-robot collaboration in an ablative pilot study of an assembly use case. Our robot demonstrations and videos are available at \url{https://sites.google.com/view/hierarchicalintentiontracking}.

翻译：协作机器人需要在工业装配等低结构化任务中有效估计人类意图，以安全、流畅地与人类共同工作，而此类任务中人类意图会持续变化。我们提出意图追踪概念，并引入一种能同时追踪分层意图的协作机器人系统。高层意图追踪用于估计人类的交互模式，使机器人能够：(1) 避免与人类碰撞以最小化干扰；(2) 辅助人类纠正错误。低层意图估计为机器人提供与任务相关的信息。我们在UR5e机器人上实现该系统，并在装配用例的消融实验研究中展示了稳健、无缝且符合人体工程学的人机协作。相关机器人演示视频详见 \url{https://sites.google.com/view/hierarchicalintentiontracking}。