[Paper Review] Robotic Sewing and Knot Tying for Personalized Stent Graft Manufacturing

Yang Hu, Lin Zhang+2 more|arXiv (Cornell University)|Mar 22, 2018

Anatomy and Medical Technology15 references3 citations

TL;DR

This paper presents a vision-guided robotic sewing system with a custom dual-arm setup and closed-loop visual servoing for automated, high-accuracy sewing of personalized stent grafts. It achieves sub-millimetre stitching precision (2–5 mm) and enables continuous overhand knot tying via a novel thread manipulator, significantly improving reliability over manual or conventional automated methods.

ABSTRACT

This paper presents a versatile robotic system for sewing 3D structured object. Leveraging on using a customized robotic sewing device and closed-loop visual servoing control, an all-in-one solution for sewing personalized stent graft is demonstrated. Stitch size planning and automatic knot tying are proposed as the two key functions of the system. By using effective stitch size planning, sub-millimetre sewing accuracy is achieved for stitch sizes ranging from 2mm to 5mm. In addition, a thread manipulator for thread management and tension control is also proposed to perform successive knot tying to secure each stitch. Detailed laboratory experiments have been performed to access the proposed instruments and allied algorithms. The proposed framework can be generalised to a wide range of applications including 3D industrial sewing, as well as transferred to other clinical areas such as surgical suturing.

Motivation & Objective

• To address the high cost and long lead times of manually fabricated personalized stent grafts used in endovascular aneurysm repair.
• To overcome limitations of existing automated sewing systems that are restricted to flat surfaces, specific stitch types, or suffer from low success rates due to needle handling issues.
• To develop a versatile, automated robotic system capable of performing diverse sewing tasks—running stitches and knot tying—on complex 3D anatomical structures like stent grafts.
• To improve reliability and consistency in stent graft manufacturing by enabling automated, repeatable knot tying to secure each stitch.
• To generalize the system for broader applications in 3D industrial sewing and minimally invasive surgical suturing.

Proposed method

• A dual-arm robotic system integrates an ABB YuMi® robot for global positioning and a custom robotic sewing device for local needle manipulation.
• Closed-loop visual servoing using RGBD depth sensing enables real-time, accurate positioning of the sewing device relative to the target fabric.
• A trajectory planning algorithm adjusts needle path and stitch size (2–5 mm) to achieve sub-millimetre accuracy across varying stitch dimensions.
• A dedicated thread manipulator with force sensing enables continuous overhand knot tying without thread cutting, ensuring consistent tension and knot security.
• The sewing device uses a double-pointed curved needle with thread attached at the center, eliminating needle drop risks common in traditional needle holder systems.
• The system employs markerless tracking and depth camera feedback (640×480 resolution) to guide stitching, with potential for future upgrades to higher-resolution sensors.

Experimental results

Research questions

• RQ1 Can a robotic system achieve sub-millimetre accuracy in sewing 3D structured objects like stent grafts using visual servoing and custom hardware?
• RQ2 Can a single robotic system perform multiple sewing tasks—running stitches of varying sizes and successive knot tying—on complex anatomical grafts?
• RQ3 How does the integration of a thread manipulator with force sensing improve the reliability and consistency of automated knot tying in stent graft manufacturing?
• RQ4 What are the key limitations of current depth sensing and visual feedback in robotic sewing, and how can they be mitigated through system design and hardware upgrades?
• RQ5 To what extent can this robotic sewing framework be generalized to other clinical applications such as surgical suturing or industrial 3D fabric sewing?

Key findings

• The system achieves sub-millimetre sewing accuracy across stitch sizes ranging from 2 mm to 5 mm, demonstrating high precision in 3D structured object sewing.
• The custom sewing device enables reliable needle handling with a nominal switching time of 16 seconds, reducing the risk of needle drop compared to traditional needle holder methods.
• The thread manipulator successfully performs continuous overhand knot tying without thread cutting, enabling secure, successive knot application for each stitch.
• The system demonstrated successful autonomous execution of both running stitches and knot tying on stent graft prototypes, with results comparable to commercial handmade grafts.
• Limitations were identified in knot tightness due to elastic thread and suboptimal pull direction; however, the system's performance is expected to improve with optimized knot-tying kinematics and hardware upgrades.
• The use of RGBD-based visual servoing enables accurate device positioning, though depth resolution and noise in point clouds remain challenges that can be addressed with higher-resolution cameras in future iterations.