A RootBot, a soft-growing robot inspired by plant roots, has been developed for the high-curvature ground excavation. Its innovative design allows efficient steering and soil removal within constrained spaces. RootBot is expected to bring a paradigm shift in landscapes of urban infrastructures and various engineering practices.

 

Biomimetics, the art of drawing innovation from nature's design, is evolving to meet urban challenges. With cities expanding, the demand for precise tunneling in complex underground networks has never been more critical. A collaborative research team led by Prof. Jee-Hwan Ryu and Tae-Hyuk Kwon in the Department of Civil and Environmental Engineering at KAIST has introduced a RootBot, an excavation robot inspired by plant roots, promising transformative advancements in urban engineering. This soft-growing marvel uses its root-inspired design to navigate subterranean landscapes in rapidly evolving cities.

 

In the intricate world of plants, roots stand out for their ability to navigate obstacles and seek nutrients, as illustrated in Fig. 1A. The growth of plant roots involves three key mechanisms: cell differentiation, elongation, and division. RootBot, the soft-growing excavation robot, strategically emulates the propulsion mechanism of plant roots, initiating its journey with an inflated soft plastic tube  propelled by air pressure (Fig. 1B). This unique locomotion, driven by growth, sets RootBot apart from conventional excavation systems and offers unparalleled flexibility in navigating diverse distances and intricate routes.

 

 

 

 

Mock-up experiments were meticulously designed to evaluate the RootBot prototype's excavation capabilities, and the setup involved a comprehensive array of peripheral equipment, including water supply, vacuum suction, air supply, tube feed, cutterhead rotation control, and data acquisition. The directional excavation test, featuring a moderate steering angle at a constant cutterhead rotation speed of 30 RPM, demonstrated RootBot's gradual rotation with steering angles from 18 to 41 degrees during directional excavation (Fig. 3A). In pursuit of sharper steering, the sustained pressure difference above 50 kPa led to continuous rotation, exceeding a 90-degree steering angle (Fig. 3B). The estimated curvature radius for this curved excavation reached 42 cm, 2.1 times the width of the excavation module. 

 

 

 

RootBot, with its plant-inspired ingenuity, shows promise for meticulous excavation in confined spaces. In mock-up experiments, the prototype exhibited a speed of 0.82 mm/min in wet-compacted sand and showcased adept steering at high curvature. The potential applications include directional excavation, precise soil removal in confined spaces, and adept navigation through intricate, curved routes to overcome unforeseen underground obstacles. This work has been featured in Acta Geotechnica (Han et al. 2023).

 

Han, G., Seo, D., Ryu, JH. et al. RootBot: root-inspired soft-growing robot for high-curvature directional excavation. Acta Geotech. (2023). https://doi.org/10.1007/s11440-023-02073-2