A novel actuated tether design for rescue robots using hydraulic transients

In the world of search and rescue robotics, particularly for search, smaller is better. Small robots can get into tighter places and are more maneuverable. With diminishing size, however, providing adequate power and communications becomes a problem. Communication is problematic if the search site is a collapsed building were transmitted signals have to travel through layers of concrete and steel. Tethers are good for providing power and communication, but tethers get caught and small robots have difficulty with the added drag of the tether. This work proposes a self-actuating tether capable of moving its own weight and remaining free while traversing around corners. Tether motion is due to induced high pressure water transients formed by rapidly arresting flow through the tether. A number of tests performed on a constructed tether prototype are presented. A simplified model of the water transients to better understand design parameters is outlined and simulated, and force measurements are collected to validate the simulation results.