commercial market in the second half of 2009.
The Vehicle
The HAUV is an ROV-form-factor UUV that is a selfpropelled, unmanned underwater vehicle, able to be deployed by two people. It weighs 78 kg and measures 42 x 40 x 25 cm, and is made up of the following components: · six hubless bi-directional DC brushless thrusters · a main electronics housing containing core electronics · a pressure tolerant, rechargeable, 1.5 kWh lithium polymer battery · an independently controlled payload tray mounted with a DVL and a DIDSON Sonar · a 1200 kHz RD Instruments DVL · Sound Metrics DIDSON imaging sonar · flotation foam · ballast weight Data transmission between the vehicle and the operator station is through a fiber optic tether, though the tether is only needed if the operator requires immediate data and visual feedback. Otherwise, the vehicle is able to operate free from physical connection, recording data for download upon retrieval. Central to the HAUV's capabilities is its ability to achieve full hull-relative navigation control, meaning that the vehicle can be operated without having to install any equipment on or around the hull. While designed to work autonomously, the operator can, with a tethered HAUV, take control via joystick and steer the vessel for a closer look at objects of interest. "You toss the vehicle in the water and it goes," Kelly said. The vehicle senses the hull by DVL, and relative nav36 MTR
igation and control is via DVL, IMU and depth sensors. The vehicle maintains a consistent and safe distance away from the hull, and six thrusters provide control as the vehicle navigates its survey path. "The capability requirement is to do the job without having any `a-priori' knowledge of the hull to be surveyed," Kelly said. Using DIDSON provided by Sound Metrics, the HAUV consistently provides a video quality picture in turbid or dark water. The vehicle is designed for ease of operation, and according to Kelly one of its main advantages is the fact that a trained ROV operator is not needed to run a mission. Before deploying the vehicle, the operator needs to simply answer five questions (such as stand-off distance, spacing between passes, etc.) in the Bluefin Operator Software Tool Suite; place the vehicle in the water and drive it close to the hull, on the surface, under operator control. The operator then, on the computer, clicks "auto", the vehicle senses the hull by DVL, and the vehicles six thrusters provide control as it navigates a survey path a consistent and safe distance from the hull. Data from the DIDSON sonar is viewed in real-time via the fiber optic tether, or, when in operation in full autonomous mode, the data is recorded and retrieved with the vehicle. While the vehicle is fully autonomous, the operator can take control of the vehicle via a joystick to revisit a particular area of interest. Even in this mode, however, the vehicle maintains an optimum altitude and position from the hull. According to Kelly, achieving hull-relative navigation and control with limited prior knowledge of the hull was one of the greatest challenges in creating the HAUV, but ironically, with the vehicle's success, this challenge has essentially become a strength of Bluefin Robotics.
May 2009
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