When significant calamities strike and buildings collapse, individuals may find themselves ensnared beneath debris. Rescuing victims from these perilous conditions can be hazardous and physically demanding. To assist rescue crews in navigating these structures, MIT Lincoln Laboratory, in partnership with researchers from the University of Notre Dame, introduced the Soft Pathfinding Robotic Observation Unit (SPROUT). SPROUT is a vine-like robot — a pliable machine that can extend and maneuver around barriers and through confined spaces. First responders can deploy SPROUT beneath fallen structures to investigate, chart, and identify optimal entry pathways through the wreckage.
“The urban search-and-rescue landscape can be harsh and relentless, where even the most resilient technologies find it challenging to function. The inherent design of the vine robot alleviates many obstacles that other systems encounter,” states Chad Council, a member of the SPROUT team, led by Nathaniel Hanson. The program is carried out under the laboratory’s Human Resilience Technology Group.
First responders consistently incorporate technology, including cameras and sensors, into their procedures to comprehend complicated operational environments. Nevertheless, many of these technologies possess limitations. For instance, cameras engineered specifically for search-and-rescue missions can only investigate in a linear fashion inside a collapsed structure. If a team desires to search deeper into a debris pile, they must create an entry point to access the next area within the space. Robots excel at exploring the tops of rubble heaps but are poorly equipped for scouring tight, unstable structures and incur substantial repair costs if damaged. The challenge addressed by SPROUT is the ability to navigate under collapsed structures utilizing a cost-effective, user-friendly robot that can carry cameras and sensors while traversing convoluted paths.
SPROUT is constructed from an inflatable tube made of sealed fabric that unfolds from a stationary base. The tube inflates with air, and a motor regulates its deployment. As the tube extends into the debris, it can bend around corners and navigate through narrow openings. A camera and other sensors attached to the tube’s tip capture images and map the environment in which the robot is operating. An operator maneuvers SPROUT with joysticks, observing a screen that showcases the robot’s camera output. Currently, SPROUT can extend up to 10 feet, and the team is working on enhancing it to 25 feet.
During the development of SPROUT, the team tackled several challenges regarding the robot’s flexibility. Since the robot is constructed from a pliable material that bends at multiple points, determining and controlling its shape as it extends through the environment is quite complex — akin to attempting to manage a growing, wiggly sprinkler toy. It was crucial to identify how to apply air pressure within the robot so that steering becomes as straightforward as pointing the joystick forward to prompt the robot to move ahead, making it more amenable to adoption by emergency responders. Furthermore, the team needed to design the tube to reduce friction during the robot’s growth and engineer the controls for steering.
Although a teleoperated system serves as an excellent initial approach for evaluating the dangers of void spaces, the team is also exploring innovative methods to utilize robotic technologies in this field, such as employing data gathered by the robot to create maps of subsurface voids. “Collapse occurrences are infrequent but catastrophic. In robotics, we typically desire ground truth measurements to validate our methods, but such data simply doesn’t exist for collapsed structures,” remarks Hanson. To address this challenge, Hanson and his team developed a simulator that enables them to create realistic representations of collapsed structures and formulate algorithms to map void spaces.
SPROUT was developed in collaboration with Margaret Coad, a professor at the University of Notre Dame and an MIT alumnus. When seeking collaborators, Hanson — also a Notre Dame graduate — was already familiar with Coad’s research on vine robots for industrial inspections. Coad’s expertise, alongside the laboratory’s proficiency in engineering, solid partnership with urban search-and-rescue teams, and capability to develop fundamental technologies and transition them to industry, “made it a natural fit to unite our efforts and focus on research for a community that has typically been underrepresented,” Hanson states. “As one of the principal inventors of vine robots, Professor Coad contributes invaluable knowledge regarding the fabrication and modeling of these robots.”
Lincoln Laboratory evaluated SPROUT with first responders at the Massachusetts Task Force 1 training facility in Beverly, Massachusetts. These evaluations allowed researchers to enhance the robot’s durability and portability and discover how to extend and steer the robot more effectively. The team is planning a broader field study this spring.
“Urban search-and-rescue teams and first responders play vital roles within their communities but often operate with limited or nonexistent research and development budgets,” Hanson remarks. “This initiative has allowed us to advance the technology readiness level of vine robots to a stage where responders can engage in a practical demonstration of the system.”
Hanson further notes that sensing in confined spaces is not an issue unique to disaster response sectors. The team envisions utilizing the technology in the maintenance of military systems or crucial infrastructure in hard-to-reach locations.
The initial emphasis of the program was on mapping void spaces, but forthcoming efforts aim to pinpoint hazards and evaluate the feasibility and safety of operations amid debris. “The mechanical capabilities of the robots have an immediate impact, but the ultimate aim is to rethink how sensors are leveraged to improve situational awareness for rescue groups,” explains Hanson. “In the end, we aspire for SPROUT to deliver a comprehensive operational overview to teams before anyone steps into a pile of rubble.”