Aqua-Quad - Hybrid Mobility and Sensing in Support of Collaborative Undersurface Warfare

Abstract

Project Summary: The project builds an experimental model as a proof of concept of a novel anti-submarine warfare (ASW) platform, AquaQuad. The envisioned vehicle is a hybrid, including features and capabilities of an energy independent drifting sonobuoy and a multirotor vertical take-off and landing unmanned aerial vehicle (UAV). As such, AquaQuad integrates a multicopter UAV with a tethered acoustic sensor, environmentally hardened electronics, communication links, and a solar recharge system. As a single system the AquaQuad design is easily scalable which enables its modification to different sensor modalities, weight of payload, communication, and energy harvesting requirements. In turn, multiple cooperative AquaQuads are designed 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 with lower dilution of precision (DOP), collision avoidance, and communication with neighboring vehicles. Overall, the distributed swarm of energy independent and autonomous AquaQuads represents an information harvesting and communication system that, depending on the specific objectives, can be focused on various naval and civil applications. To date the project has identified the mathematical models of key subsystems of the AquaQuad in the major modes of operation. They include two distributed (over depth) components - the surface and submerged units, connected via a tether, which operate autonomously in passive search while in energy harvesting drift and in energy bursting flight modes; a number of sub-modes is envisioned/included to address the specific nature of silent operation under strict communication and energy constraints. An experimental setup of the surface unit and the submerged data acquisition (DAQ) system has been built. Operational capabilities of separate components are verified in controlled laboratory experiments. System identification experiment has been performed to identify the maximum achievable capabilities of the ARM-based data acquisition system and the potential bottlenecks of the envisioned information processing architecture. The power distribution and communication subsystem has been conceptualized and prototyped in hardware to enable practical evaluation of the power transmission and data exchange bandwidth over a dual wire tether. The corresponding communication mechanism (hardware and the communication protocol) is outlined to enable embedded microcontroller implementation. The long haul and local wireless communication are adopting the existing Iridium and 802.11x solutions where the bandwidth available drives the underlying decision making and data preprocessing tasks.