Environment modelling of Great Barrier Reef habitats using Autonomous Transect Surveying

This project has as its aim the development of algorithms and methods capable of modelling natural reef environments using data collected by an autonomous robotic system capable of surveying and documenting change on the Great Barrier Reef.  The long term goals of this work are to provide a set of tools to support research into the ecologically sustainable use and protection of tropical coral reefs, especially the Great Barrier Reef World Heritage Area, and other marine habitats.  The Australian Institute of Marine Sciences recognizes the importance of monitoring reef habitats and asserts that coral reef monitoring is fundamental in Australia for the sustainable management of the Great Barrier Reef, the largest World Heritage Site in the world. 

This project is developing novel methods for collecting and interpreting data suitable for monitoring of coral reefs using a submersible robotic vehicle and will result in the development a novel tool suitable for benthic surveys.  The University of Sydney's Australian Centre for Field Robotics (ACFR), part of the ARC Centre of Excellence for Autonomous Systems, has a small research Autonomous Underwater Vehicle (AUV) capable of undertaking such survey work.  This experimental platform is a mid-size robotic vehicle called Seabed (see Figure 1). The submersible is equipped with a mechanically scanned low frequency terrain-aiding sonar, a depth sensor, Doppler Velocity Log (DVL), Ultra Short Baseline Acoustic Positioning System (USBL), forward looking obstacle avoidance sonar, fibre-optic gyroscope, compass with integrated roll and pitch sensors and two colour CCD cameras.  Figure 2 shows an example of a visual mosaic recovered by stitching together successive frames from another of our vehicle's vision systems.  The vehicle is controlled by an on-board, PC-104 based computing platform which is used for sampling sensor information and running the vehicle's low-level control algorithms.  This platform is intended primarily as a research platform on which to test the novel navigation and sensing strategies proposed by this work. This vehicle is currently being prepared for deployment on the Great Barrier Reef around the University of Sydney's One Tree Island Research Station.

This research work aims to develop a theoretical framework with which to fuse information from a variety of sensors available in the underwater domain for the construction of detailed environmental models.  This will require the selection of a general solution to the problem of data fusion appropriate for use with subsea sensors.  Work to date in this area has concentrated on methods for building a model of the environment while simultaneously estimating the path taken by a vehicle based on observations taken with its on-board sensing systems.  Figure 3 shows an example of the vehicle path estimate and sonar terrain model recovered by fusing information from the vehicle's on-board vision and sonar systems.  Finally, Figure 4 shows some of the visual frames texture mapped onto a terrain model showing the correspondence between the recovered map and the visual features.