Aqua-Quad - solar powered, long endurance, hybrid mobile vehicle for persistent surface and underwater reconnaissance, part II - onboard intelligence

The paper describes the control system development of a novel hybrid autonomous vehicle - Aqua-Quad, a Multi-Rotor Vertical Take Off and Landing aircraft with environmentally hardened electronics, exchangeable sensor suite, communication links, and a solar recharge system. The key objective of this multi-modal autonomous system is to enable energy-aware ultra-long endurance autonomy to facilitate near real-time capture and transition of information from the undersea domain to the air and further to the ground. The key benefit of this rapid in-situ data delivery is to enable timely and efficient decision making that, in turn, improves the collective efficiency of the Aqua-Quad as a system. Each individual vehicle is designed to have mission-relevant sensors and sufficient computational power to reduce the false alarm rate, and navigate in open seas in an energy-optimal manner by optimizing its route while either in search of targets or when tracking them. Higher operational efficiency is envisioned when a flock of Aqua-Quads operates cooperatively. The paper focuses on the design of energy-optimal path planning for a single vehicle in the presence of ocean currents. A novel modification of rapidly exploring random tree algorithm is developed to fully utilize the energy savings provided by the transportation mechanism of ocean flows.