• Latching mechanism between UAV and UGV team for mine rescue

      Hoffman, Sarah; Peterson, Rorik; Hatfield, Michael; Lin, Chuen-Sen (2017-08)
      Safety is a concern in the mining industry when a tunnel collapse could result in the casualties and deaths of workers and rescuers due to the hazards posed to them. The Alaska Center for Unmanned Aircraft Systems Integration (ACUASI) is working on a project to increase mine safety by sending an Unmanned Ground Vehicle (UGV) fit with LiDAR sensors and an Unmanned Aircraft Vehicle (UAV) to map the tunnels and to find a collapsed tunnel in an effort to determine the location and condition of trapped workers. The UGV will drive to the collapsed tunnel, at which point the U AV will launch to find any gap in the tunnel that it could fly through to assess the damage. This overall project requires a releasing and latching system to secure the UAV, allow it to launch at the appropriate location, and dock the UAV when its mission is complete or its battery needs recharging. A simple pin-through design was adopted to latch and release the UAV by implementing a Scotch yoke and servo as the actuator. All necessary components were analyzed for stress using two forces, 16 N (maximum takeoff weight of the potential UAV) and 150 N (im pact force of the maximum w eight of the potential UAV from 0.15 m or just under 6 inches). Three sets of properties for PLA were applied in the stress analyses to thoroughly investigate the feasibility of creating the parts out of PLA, a commonly used plastic for 3D printing. These three property sets were found in literature and consisted of bulk values of PLA, empirically determined values of 3D printed PLA, and values calculated using porosity equations. It was found that most components would function satisfactorily without risking fracture except in extreme conditions. The stress analyses for the landing gear illustrated its weaknesses, revealing a potential need for a different material or redesign. The landing gear as it is could be utilized under nominal operation, but it could not withstand any significant impact such as one that might occur in the event of a hard landing. The latching mechanism itself succeeded in securing the UAV. Future work includes redesigning the landing gear, another design concept for a latching mechanism that may prove more reliable, and adjusting the landing pad in the event a different UAV is selected.