Rebar-tying Robot based on machine vision and coverage path planning

•Developed an efficient automated rebar-tying robot for precast slab production.•Proposed an intersection detection method using a multi-segment fitting method.•Designed a coverage path planning method to maximize tying efficiency.•Achieved 99.4 % accuracy in intersection detection, with errors within 2.8 mm.•Average rebar tying time is 5.5 seconds, faster than most robots. Automation technology can replace manual work in the traditional construction industry, improve quality and efficiency, and reduce costs. This paper developed a rebar-tying robot for tying the intersection of rebars. It proposed a Hough transform multi-segment fitting method to detect the intersections of rebars in real-time acquired RGB-D images. To cover the surface of the rebar net as much as possible under the condition of limited camera FOV, this paper designed a coverage path planning method to plan the path of the photo positions and the detected intersections of rebars efficiently and orderly. The experimental results show that the robot achieved an accuracy rate of 99.4 % in intersection detection, the detection error is within 2.8 mm, the single tying time is 1.85 s, and the average tying time is 5.5 s, which is faster than most robots. The robot realizes the task of automatically tying the intersection of rebars, which is robust and efficient, without duplication or omission.