Source-linked AI summary
A Multi-Vine Soft Robot Enabling Accessible Working Channel and Steering
Reza Kashef, Cem Suulker, Mohammad Sheikh Sofla, Kaspar Althoefer
TL;DR
Vine robots need active steering for sharp directional changes and payload delivery without restricting tool access. This paper introduces two independently actuated vines coupled to an externally integrated working channel, and demonstrates nearly 90° steering during growth. The architecture supports navigation through a colon phantom while retaining less restricted tool delivery.
Problem
Sharp directional changes can limit passive vine-robot growth, while integrated working channels constrain tool size, add friction, and restrict environmental access to the robot tip.
Method
The paper couples two independently actuated vine robots to an externally integrated working channel through soft mounting tips.
Results
The multi-vine robot demonstrated nearly 90° steering during growth and maneuvered through a colon phantom while carrying the working channel.
Takeaways & Limitations
The architecture supports less restricted tool delivery while enabling maneuverability in confined environments such as a colon phantom.
Abstract
from arXiv · showhide
Soft eversion robots, also known as vine robots, have attracted growing interest for navigation and inspection tasks, including minimally invasive medical applications [1]. A vine robot consists of a thin, flexible, inextensible tube folded inward that everts and grows forward when pressurized. This tip-growth enables navigation with minimal friction, making vine robots well suited for complex environments such as the human colon [2]. While their inherent softness allows passive conforma- tion to curved pathways in confined spaces, navigation performance strongly depends on environmental inter- actions, including contact angle and the length of un- constrained deployed material [3], [4]. Sharp directional changes, such as those in the sigmoid colon, often limit passive growth and necessitate active steering. Existing solutions include distributed artificial muscles [5] or dedicated tip-based steering mechanisms [6]. In addition, many applications require payload delivery, such as sensors and tools [7], [8]. Within the ERC Synergy project EndoTheranostics, this motivates the development of vine robots capable of delivering micro- surgical tools during growth. Prior work has integrated working channels within the vine body [8], [9], but these approaches constrain tool size, introduce friction, and limit access to the environment to the robot tip. In this work, we propose a multi-vine architecture in which two vine robots are coupled to an externally integrated working channel via soft mounting tips [10]. Independent vine actuation enables active tip steering while advancing the working channel without embed- ding it within the vine bodies Figure 1. Experiments demonstrate sharp steering of nearly 90 degrees during growth, highlighting the potential of this architecture for versatile medical and non-medical applications.
MATERIALS AND METHODS
The multi-vine robot uses independently actuated vines and an externally anchored working channel to control straight growth, sharp turns, and advancement. Its components include soft caps, LDPE vine bodies, and a silicone working channel.
- Control strategy: Both vines are inflated at the same pressure for straight growth while the working channel advances freely.
- Control strategy: Pressurizing one vine while locking the working channel induces buckling and a sharp turn; reversing actuation changes the turning direction.
- Control strategy: Growth speed is controlled by adjusting the working-channel advancement speed, while the caps remain positioned during growth.
- System architecture: The system comprises two soft-capped vine robots linked to an externally anchored working channel.
- Fabrication: The vines are 1.5 m LDPE tubes that expand to approximately 10 mm or 20 mm diameters, with a 6 mm-outer-diameter silicone working channel.
RESULTS
The multi-vine system achieved controlled forward navigation and steering in open environments and passed a 90° bend in a colon phantom while carrying its working channel.
- Colon phantom navigation: 90° bend: the 10 mm-vine system successfully passed through a colon phantom while carrying the working channel.
- Open-environment navigation: The robot grew forward, turned controllably, and entered a pipe opening accurately in an open environment.
- Growth pressure: The 10 mm vine required higher growth pressure than the 20 mm vine because of higher friction, but both remained below burst pressure.
- Growth pressure: Adding a soft cap did not noticeably change growth pressure, although turning and steering required higher pressures than minimum growth.
DISCUSSION
The paper presents a multi-vine architecture for navigation and payload delivery that keeps the working channel external to the vine bodies. The system maneuvered through a colon phantom, while future work targets quantitative steering evaluation and access along the robot body.
- Contribution: The architecture couples two vine robots with an externally integrated working channel to improve navigation and payload delivery.
- Contribution: Keeping the working channel external enables less restricted tool delivery than designs with channels integrated within the vine body.
- Demonstration: The multi-vine robot demonstrated sufficient maneuverability to grow through a colon phantom.
- Future work: Future work will quantitatively characterize steering gains and develop working-channel access along the robot body, not only at its tip.