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AquaQuad -Hybrid Mobil Vehicle for Persistent Surface and Underwater Reconnaissance

The objective of the effort is to build an experimental model as a proof of concept for a novel anti-submarine warfare platform, Aqua-Quad. The envisioned vehicle is a hybrid, including features and capabilities of a drifting sonobuoy and a multirotor vertical take-off and landing UAV. As such, Aqua-Quad integrates a quadcopter UAV with a tethered acoustic sensor, environmentally hardened electronics, communication links, and a solar recharge system. The Aqua-Quads are envisioned as hybrid-mobile, collaborative platforms that ride on ocean currents and fly over significant distances when required by the mission. Flight is triggered to enable rapid repositioning for submarine tracking, collision avoidance, and communication with neighboring vehicles. The initial effort addressed some of the conceptual questions including the CAD-based design and packaging of onboard capabilities, feasibility of the energy balance, onboard sensing and target tracking capabilities, and initial mission and path planning. The current focus is to find the design solutions (both hardware and software) that would demonstrate the Aqua-Quad's ability to perform stealthily intelligence, surveillance, and reconnaissance operations, fully autonomously, for extended periods of time.

In the envisioned scenario, a “flock” of Aqua-Quads is outfitted with deployable, passive acoustic/magnetic sensors, and distributed in a grid over the sea surface to search for undersea objects of interest. Mobility of the network of Aqua-Quads is first used to form the electronic detection fence of optimal density. The first vehicle that picks up a signal and collects a sufficiently rich sample might pop-up high enough to form a network with nearby Aqua-Quads to announce its detection and to enable cooperative target motion estimation (distance/bearing only, TDOA etc.), or to relay the information to nearby manned or unmanned surface or airborne assets including the communication of data over a satellite link.

Vehicles in the flock could take turns flying and sensing to overcome the flight-endurance limitation, and the use of mobile mesh networking technology would make this exchange transparent to the world. In the worst case scenario, if there are no Aqua-Quads nearby, the ability to relocate rapidly over sufficient distances will enable successful target motion estimation with optimal dilution of precision (DOP). During times of flight, they may relocate using a leap-frog approach to follow a moving target, or while floating the flock can estimate the strength and direction of the current, and may then take advantage of the current for efficient travel during repositioning. Thus, riding on ocean currents is another mechanism that saves energy while on patrol.
NPS Naval Research Program
NPS Naval Research Program