A new flexible robot helps emergency responders search through rubble
When major disasters hit and structures collapse, people can become trapped under rubble. Extricating them can be dangerous, as it is exhausting physical work, and the environments can be hazardous. First responders regularly integrate technology, such as cameras and sensors, into their workflows to understand the complex operating environment. While cameras specially built for search and rescue operations, such as a SearchCam, can provide situational awareness, they can probe only on a straight path inside a collapsed structure. If a team wants to search further into a pile, they need to cut an access hole to get to the next area of the space. Robots like Spot from Boston Dynamics are good for exploring on top of rubble piles but are ill-suited for subsurface void spaces due to replacement costs if unstable structures damage the robot. The challenge then becomes how to get under collapsed structures using a low-cost, easy-to-operate robot that can carry cameras and sensors and traverse winding paths.
To tackle this challenge, Laboratory staff in the Humanitarian Assistance and Disaster Relief Systems Group, led by staff member Nathaniel Hanson, and in collaboration with researchers at the University of Notre Dame, developed the Soft Pathfinding Robotic Observation Unit (SPROUT). SPROUT is a vine robot — a soft robot that can grow and maneuver around obstacles and through small spaces — and is deployable under collapsed structures in order to explore, map, and find optimum ingress routes thorough debris.
“The urban search and rescue (USAR) environment can be brutal and unforgiving, where even the most hardened technology struggles to operate, but the fundamental way a vine robot works mitigates a lot of the challenges that other platforms face,” says Chad Council, who is a member of the SPROUT team.
SPROUT is composed of an inflatable tube made of airtight fabric that is fixed to a base. When used, the tube inflates with air, and a motor controls the deployment. A specially designed camera mount holds a sensor mount along with multiple sensors that help image and map the environment the robot is navigating. Operators steer SPROUT with joysticks and a screen connected to the robot’s base displays what the robot sees via a sensor payload. Currently, SPROUT can deploy up to ten feet and the team is now working on expanding it to 25 feet.
When building SPROUT, the team had to overcome a number of challenges related to the robot’s flexibility. Typical robots feature rigid parts that don’t need to bend, meaning that it’s fairly easy to determine the position of the robot through kinematic math. Vine robots like SPROUT, however, are composed of deformable material that can bend at nearly every point, meaning the shapes they contort into are very difficult to determine. Therefore, as SPROUT unfurls under pneumatic air pressure, it has more points to bend and is therefore harder to steer – think of trying to control an expanding water wiggly toy or a telescoping light saber. Pinpointing how to control and apply air pressure within the robot so that steering is as simple as pointing the joystick forward to make the robot move forward, was essential for system adoption by emergency responders. In addition, the team also had to design the tube to minimize friction while the robot grows and engineer the controls for steering.
While a teleoperated system is a good starting point for assessing the hazards of void spaces, the team is also finding new ways to apply robot technologies to the domain, such as using data captured by the robot to build maps of the subsurface 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,” says Hanson. To solve this problem, Hanson and his team made their own simulator, which allows them to create realistic depictions of collapsed structures and develop mapping algorithms that work inside the void space.
SPROUT was developed in collaboration with Professor Margaret Coad — a graduate from MIT — and her team at the University of Notre Dame. When looking for collaborators, Hanson — a graduate of Notre Dame — was already aware of Coad’s work on vine robots for industrial inspection. Together with the Laboratory’s expertise in systems engineering, its strong partnership with USAR teams, and ability to develop fundamental technologies and prepare them for transition to industry, “it was a really natural pairing to join forces and work on research for a traditionally underserved community,” Hanson says.
“As one of the primary inventors of vine robots, Professor Coad brings invaluable expertise on the fabrication and modeling of these robots,” says Hanson. “Notre Dame institutionally has a strong mission to aspire to the common good through technology; this makes them ideal partners for the Laboratory’s Humanitarian Assistance and Disaster Relief Systems group.”
SPROUT has been tested two different times at the Massachusetts Task Force 1 training site in Beverly, MA, one of those times together with first responders, and the tests have allowed team members to improve the durability and portability of the robot as well as learn how to grow and steer the robot more efficiently. The team is planning a larger field study in the spring.
“USAR and first responders serve critical roles in their communities but typically have little to no research and development budgets,” says Hanson. “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. Moreover, sensing in constrained spaces is not a problem that is unique to the USAR communities. We envision this technology being used in the maintenance of military systems and critical infrastructure with difficult-to-access locations.”
The initial program focused on mapping void spaces, but future work aims to localize hazards and assess the viability and safety through rubble. “Simply put, there is an immediate effect to be had simply through the mechanical performance of the robots, but the real goal is to rethink the way the sensors are used to create a more complete operating picture for the USAR teams,” says Hanson. “Ultimately, we want SPROUT to provide a complete operating picture to teams before anyone enters a rubble pile,” says Hanson.
The SPROUT team is currently seeking external funding, along with other institutional partners. Contact Anne McGovern to inquire.