Vine-Like Robot Developed for Under-Rubble Search and Rescue

Researchers at Lincoln Laboratory and the University of Notre Dame have created SPROUT, a vine robot designed to navigate beneath collapsed buildings.

In the aftermath of structural collapses, individuals may become trapped beneath debris, and rescuing them involves significant risks and physical effort.

To assist rescue teams in navigating such environments, MIT Lincoln Laboratory, in collaboration with the University of Notre Dame, developed the Soft Pathfinding Robotic Observation Unit (SPROUT).

SPROUT is a type of soft robot, known as a vine robot, that can extend and maneuver around obstacles and through confined spaces. First responders can deploy SPROUT under collapsed structures to explore the area, map the environment, and identify optimal entry routes through the rubble.

The urban search-and-rescue environment can be brutal and unforgiving, where even the most hardened technology struggles to operate. The fundamental way a vine robot works mitigates a lot of the challenges that other platforms face.

Nathaniel Hanson, Lincoln Laboratory, Massachusetts Institute of Technology

The SPROUT team, led by Nathaniel Hanson, operates within the Human Resilience Technology Group at MIT Lincoln Laboratory.

Emergency responders typically use tools like cameras and sensors to understand complex and hazardous environments. However, many of these tools have limitations. For instance, search-and-rescue cameras can only capture views directly in front of them within collapsed structures. To explore further, teams often need to create new openings.

While robots are useful for navigating on top of rubble, they face challenges in tight, unstable spaces and can be costly to repair if damaged. SPROUT aims to address the challenge of exploring beneath collapsed structures by offering a cost-effective, easy-to-use robot that can carry cameras and sensors and navigate winding paths.

SPROUT consists of an inflatable tube made from airtight fabric that extends from a stationary base. The tube is inflated with air, and a motor controls its extension. As it moves through debris, the tube can bend around corners and squeeze through narrow openings. A camera and other sensors attached to the end capture images and create maps of the surroundings.

An operator controls SPROUT using joysticks while viewing the robot's camera feed on a screen. Currently, SPROUT can extend up to 10 feet, with plans to extend its reach to 25 feet.

Developing SPROUT involved overcoming challenges related to the robot's flexibility. Since the material used allows the robot to bend at many points, it is difficult to predict and control its shape while it moves through the environment.

A major challenge was determining how to apply air pressure within the robot so that steering would be as intuitive as pushing a joystick forward to move the robot. Additionally, the team worked on designing the tube to minimize friction as it extends and ensuring effective steering controls.

While remotely controlling the robot provides valuable insight into potential dangers in empty spaces beneath rubble, the team is also investigating how to use the data collected by the robot to create maps of underground voids.

Collapse events are rare but devastating events. In robotics, we would typically want ground truth measurements to validate our approaches, but those simply don't exist for collapsed structures.

Nathaniel Hanson, Lincoln Laboratory, Massachusetts Institute of Technology

To address this challenge, Hanson’s team developed a simulator that creates accurate representations of collapsed structures and designs algorithms for mapping the empty spaces within them. The development of SPROUT was a collaborative effort with Margaret Coad, a professor at the University of Notre Dame and an MIT alumna.

Hanson, also a Notre Dame graduate, was already familiar with Coad's work on vine robots for industrial inspections when looking for collaborators. Coad’s specialized knowledge, combined with the laboratory's engineering expertise, strong connections with urban search-and-rescue teams, and its ability to develop foundational technologies for industrial application, were critical to the project.

Made this a really natural pairing to join forces and work on research for a traditionally underserved community. As one of the primary inventors of vine robots, Professor Coad brings invaluable expertise on the fabrication and modeling of these robots.

Nathaniel Hanson, Lincoln Laboratory, Massachusetts Institute of Technology

Lincoln Laboratory conducted field tests of SPROUT with first responders at the Massachusetts Task Force 1 training facility in Beverly, Massachusetts. These tests provided valuable feedback, helping the researchers improve the robot's durability, transportability, and steering techniques. The team is planning a more extensive field study for this spring.

“Urban search-and-rescue teams and first responders serve critical roles in their communities but typically have little-to-no research and development budgets. This program has enabled us to push the technology readiness level of vine robots to a point where responders can engage with a hands-on demonstration of the system,” said Hanson.

Hanson adds that sensing in constrained spaces is not a problem unique to disaster response communities. The team envisions the technology being used for the maintenance of military systems or critical infrastructure in hard-to-access locations.

The initial program focused on mapping void spaces, but future work will aim to localize hazards and assess the viability and safety of operations within rubble.

“The mechanical performance of the robots has an immediate effect, but the real goal is to rethink the way sensors are used to enhance situational awareness for rescue teams. Ultimately, we want SPROUT to provide a complete operating picture to teams before anyone enters a rubble pile,” said Hanson.

How a Flexible Robot Helps Find Survivors Inside Collapsed Buildings. Video Credit: MIT Lincoln Laboratory