Rubble traversal experiments of a vine robot*

In natural disasters, trapped victims face a 20% survival rate, with near-certain mortality after 48 hours. Current search and rescue robots are poor at going into rubble. Here we developed a low-cost vine robot and studied how well it can grow into simulated rubble. The soft, continuum robot body made from fabric can be steered in 3D with three pneumatic tube actuators along its entire length. The rubble testbed consists of water bottles of variable weights and shapes. We attached LEDs along the robot to observe its growth through the semi-transparent simulated rubble. We tested the robot growing into rubble of varied weights, with its tip not oscillating or oscillating in low and high frequencies. In lightweight rubble, for any tip oscillation treatment, the growing robot could always squeeze through crevices smaller than its tip diameter, and steer effectively. In heavy rubble, without tip oscillation, the robot was unable to fully grow due to limited force capacity; with the tip oscillating in low frequency, the robot could occasionally repel a blocking bottle and slightly enlarge the crevice to negotiate through; with the tip oscillating in high frequency, the robot could not successfully squeeze through due to lack of steady propulsion.