Use of highly portable micro-sized remotely operated vehicles for environmental monitoring and mapping

Historically, the task of monitoring and mapping fragile coastal ecosystems in comparatively shallow depths (less than 300 meters) has been a challenge. Divers can collect some information, sonars can do extensive acoustic study, and Autonomous Underwater Vehicles (AUVs) are playing an increasing role. However, ground truthing, fish counts, detailed coral health studies, and other tasks can require detailed and extended study. It is hazardous or impossible to conduct much of this research with divers, since they are often unable to spend sufficient time at depths to conduct intensive study. Larger remotely operated vehicles (ROVs) require large vessels with equally large budgets, and can be difficult to maneuver without damaging delicate ecosystems. For a wide variety of tasks, small, economical, and extremely portable ROVs are not only the best answer, they are the only practical answer. Until recently, however, the ROVs that have been available for these tasks lacked both integrated data collection and fusion tools, and adequate thrust to handle typical currents. Smaller ROVs were limited in both tether length and depth rating. Units were typically manufactured in fairly small numbers, making them expensive and difficult for manufacturers to thoroughly shake out problems. Sensors such as sonars, positioning systems, water quality sondes, and such were an afterthought, without regard to rapid deployment or consistent data collection. The use of disconnected and isolated technologies puts an undue burden on the scientists and resource managers who are forced to perform the role of system integrators. Resources that could be spent collecting larger data sets, both spatially and temporally, were expended on engineering development. Recent advances in underwater sensor technologies have made them much smaller, with higher accuracy and lower power consumption. Non-acoustic positioning systems can be deployed much more easily, allowing researchers to collect detailed information on the location of various ecosystems, and conveniently return to the same location to study changes and the rate of change. Software driven integrated data collection eases the task of post analysis and data presentation. Lower costs and more streamlined imagery and physical environment data collection techniques allow more frequent and consistent study at greater scales. Usability improvements are providing non-traditional users access to these tools, dramatically increasing the total aggregate amount of data collected. The technological evolution of these tools has been coupled with the development of new operational techniques. Operational phases of performing a study can be optimized for the technology being used and the results required. This minimizes deployment time, decreases on station survey time requirements, increases the amount of relevant data collected, and increases the number or area of survey sites. All of this leads to more detailed and accurate studies. New technologies, particularly new positioning and sensor systems, require specific methods to produce the best results. Operational survey and sampling techniques tailored to micro-ROV operations have been developed. Methods to augment traditional data collection operations in conjunction with ROV usage have also been developed. This paper will review the current state of the art in research tools. After a review of micro-ROV hardware and software tools that can be applied to underwater monitoring and mapping, case studies will be presented, with a focus on the tools used and the challenges overcome. An emphasis will be placed on the kinds of studies that could not have been practically conducted with other technology, and the results obtained. Future directions for technological and operational development which will facilitate environmental studies will be discussed.