Ron Lewis

A survey of AUV and robot simulators for multi-vehicle operations

This paper presents a survey of a selection of currently available simulation software for robots and unmanned vehicles. In particular, the simulators selected are reviewed for their suitability for the simulation of Autonomous Underwater Vehicles (AUVs), as well as their suitability for the simulation of multi-vehicle operations. The criteria for selection are based on the following features: sufficient physical fidelity to allow modelling of manipulators and end effectors; a programmatic interface, via scripting or middleware; modelling of optical and/or acoustic sensors; adequate documentation; previous use in academic research. A subset of the selected simulators are reviewed in greater detail; these are UWSim, MORSE, and Gazebo. This subset of simulators allow virtual sensors to be simulated, such as GPS, sonar, and multibeam sonar making them suitable for the design and simulation of navigation and mission planning algorithms. We conclude that simulation for underwater vehicles remains a niche problem, but with some additional effort researchers wishing to simulate such vehicles may do so, basing their work on existing software.

The Role of adaptive mission planning and control in persistent autonomous underwater vehicles presence

The Autonomous Underwater Vehicle (AUV) community has for many years recognized the potential benefits made by adapting mission planning on-the-fly. Over the years there has been some degree of success in applying adaptive mission planning to very specific problems. Examples of applications include capabilities for a vehicle to search for, and then modify its trajectory to follow, a feature such as a plume or a thermocline, or to modify its trajectory to avoid an obstacle, or to find and follow a feature such as a pipeline. Despite an evident increase in the number of applications, the use of adaptive mission planning is still in its infancy. There is no doubt that adaptive mission planning will play a pivotal role in future AUV persistent presence. So what is delaying this technology from making the leap towards wider industry acceptance? This paper reviews the literature in adaptive mission planning and uses a failure analysis technique to identify key obstacles for the integration of this technique in wider AUV applications. We use our failure analysis to help devise recommendations for mitigating these obstacles. The complexity of the mathematical approaches used by adaptive techniques is one key obstacle. Perhaps of more importance is that the AUV community is increasingly requiring quantitative assessment of risk associated with the use of AUVs. We propose that probability is the appropriate measure for quantifying the risk of adaptive systems and their uncertainty. The work here presented is a collective endeavor of the Engineering Committee on Oceanic Resources Specialist Panel on Underwater Vehicles.

High Resolution Seabed Sub-Bottom Profiler for AUV

Memorial University of Newfoundland (Memorial) is undertaking a novel and exciting area of interdisciplinary research and development related to Autonomous Underwater Vehicles (AUV). AUVs are an untethered, unmanned technology that enables a broad array of research, especially in hazardous underwater environments, that cannot be achieved by other means. In spring 2010, Memorial University commenced design work on a project that aims to provide a means to conduct high-resolution sub-bottom seabed surveys in water depths up to 1000 m (3281 ft), using a new imaging sub-bottom profiler technology with a 10 cm (3.9 in) resolution that has never been deployed on an AUV. The purpose of this project is to integrate a long-array sub-bottom profiler developed by PanGeo Subsea Inc. of Canada, into Memorial’s Explorer AUV by building a new vehicle section that resembles a thick airplane wing with a span of 3.5 m (11.5 ft). Memorial University is working to make the new equipment easily adaptable and removable from the Explorer AUV while in operation. The Explorer AUV equipped with this new sub-bottom profiler capability will be operational in 2012. In this paper, the underlying design criteria and challenges are discussed. A preliminary concept design is described and coarsely evaluated for technical feasibility.Copyright

The Memorial Explorer: Developing the role of AUVs in under-ice research

Autonomous Underwater Vehicles are a leading technology for under-ice deployment and research. Memorial University and its Explorer AUV, in cooperation with the University of Tasmania and the Australian Antarctic Division, has embarked on a multi-phase development program that will lead to a scientific mission in the Australian Antarctic. Completion of Phase I saw the AUV deployed in the Canadian high Arctic and acoustic data collection performed in the Australian Antarctic. Currently in Phase II, the AUV is being fitted with a full suite of survey tools and will see developments in the fields of navigation, positioning and mission completion. Phase III will see further developments in AUV technology for under-ice research, with the ultimate goal being the AUV deployed in the Antarctic for a scientific mission to explore the role of sea-ice in the Worlds climate.

The development of AUV strategies for multidisciplinary use

The Marine Environmental Research Lab for Intelligent Vehicles (MERLIN) operates an Explorer Autonomous Underwater Vehicle (AUV) that serves as a potential platform for ocean surveys over a broad range of disciplines. MERLIN undertook a four year development program to improve both the capacity and autonomy of the vehicle by acquiring multibeam, side-scan and sub-bottom profiling sonars and developing algorithms using these tools to improve the navigation of the vehicle as part of a project called Responsive AUV Localization and Mapping (REALM). The goal of REALM is to be able to pre-program the vehicle to both correct its own dead-reckoning position in a survey area and allow it to recognize Zones of Interest (ZOI). With such an improvement, programmed surveys could be modified in real time to allow the collection of additional detailed data in a ZOI. To develop an understanding of the types of data that might indicate a ZOI during a typical survey, a field program was developed for a site in Smith Sound, Newfoundland, Canada. Smith Sound was the site of the largest known overwintering inshore cod population in North America at a time when surrounding cod populations largely collapsed, creating interest in possible relationships between seabed properties and cod populations; the Sound is also of interest due to the potential presence of internal seiches and resonant tidal forcing; the area is the location of many documented, but unlocated shipwrecks; and, with depths over 200 m, is a region that is not easily explored without the use of technologies such as AUVs or other underwater vehicles. This paper presents the results of the preliminary Smith Sound survey, including an overview of the logistical planning aimed at collecting data with multidisciplinary interest. The individual data sets are presented, highlighting preliminary indications of ZOI for each topic of interest.

Preparatory Tests with an Explorer class Autonomous Underwater Vehicle for Missions under Sea Ice

The autonomous underwater vehicle (AUV) operations described here are preparatory missions to enable operation of an AUV under sea ice in polar regions. The proposed polar projects include operations under land fast ice in the Arctic through an ice moon pool and a planned project to assess sea ice mass balance and habitat assessment in the Southern Ocean in East Antarctica. This paper focuses on the preparatory missions, done in open water, and the planned Southern Ocean project. The plan is to use an autonomous underwater vehicle (AUV) for the under ice component of measurements. The ultimate goals are to quantify the size and shape of ridge keel structures and their contribution to the sea ice mass balance over a study region; to understand the processes that link sea ice with the distribution of ice algae and krill; to provide the necessary field measurements, over sufficiently large areas, for the calibration/validation of satellite and aircraft-based measurements of the sea ice and snow cover thickness; and to provide baseline measurements of sea ice thickness for future climate monitoring.

MERLIN - A decade of large AUV experience at Memorial University of Newfoundland

Autonomous Underwater Vehicle (AUV) technology has significant research potential, specifically for harsh maritime environment operations. Memorial University of Newfoundland recognized this potential and in 2005 the University commissioned an International Submarine Engineering Explorer AUV to be built. The Marine Environmental Research Lab for Intelligent Vehicles (MERLIN) was established to manage, maintain and operate the Explorer for Memorial University and any other potential AUV users. Over the course of ten years, MERLIN capabilities have grown to a full service AUV research team with harsh maritime and polar experiences. The Explorer was born in the Pacific Ocean, lives in the Atlantic Ocean and has vacationed in the Arctic. AUV research efforts have evolved from dynamic vehicle studies with basic sensor technology to integration of cutting edge sonar systems that push the boundaries of AUV design and successful implementations of original research into advanced autonomous navigation.