Unmanned Systems Technology 022 | XOcean XO-450 l Radar systems l Space vehicles insight l Small Robot l BMPower FCPS l Prismatic HALE UAV l InterDrone 2018 show report l UpVision l Navigation systems

Platform one Unmanned surface vessels operating in all weathers face the risk of capsize, immobilising them, submerging their comms antennas and potentially damaging their thruster motors if they run for an extended period out of the water (writes Peter Donaldson). These risks can be mitigated by building as much stability as is practical into the basic design of the hull, but incorporating a self-righting capability provides the opportunity to correct the problem should prevention fail. In September, China’s patent office awarded patent number CN207809697U to Beijing Yudi Technology for just such a self-righting unmanned boat. The mechanism includes a pair of buoyant chambers near the bow, one sealed and one designed to flood in a capsize. The sealed chamber can contain only air, but can also house electronic components. Should the USV capsize, the second chamber fills with water, causing the boat to settle and roll onto what the flooded chamber has made the less buoyant side. Because the USV is designed with weight distribution biased towards the stern, this submerges the thruster on the same side as the floodable chamber. Attitude sensors detect the capsize, triggering the control system to run the submerged thruster in reverse. That creates a force that works with the imbalance between the flooded and sealed chambers to right the USV. An important detail here is using curved ducting to direct the water flow from the reversed thruster at an angle of 30-60 º with respect to the centreline to increase the righting moment. When the boat is upright once more, the flooded chamber empties, balancing the buoyancy of the sealed chamber on the other side. Self-righting boat patent Marine vehicles Curved ducting directs the water flow from the thruster at an angle of 30-60 º