Mapping in the Background: Scalable capabilities using low-cost passive robotic systems for seafloor imaging

This fellowship will develop a simple approach to collect large volumes of seafloor visual imagery using fleets of low-cost, passively-drifting underwater robots. Based on the concept of the Lagrangian imaging float outlined in Roman et al., 2011 [1], this fellowship will investigate how seafloor visual observations can scale to enable several orders of magnitude larger regions of the seafloor to be surveyed at significantly lower costs and reduced effort than is possible with today's RAI systems. To achieve this, novel methods will be developed to increase the endurance of these platforms from several hours to several weeks, and enable the location of each platform in the fleet to be determined in a globally consistent way. The images obtained will be packaged into 3D visual seafloor reconstructions along the trajectories taken by the platforms as they drift on near bottom currents. This will provide valuable data for a range of scientific studies and statutory monitoring applications. While the trajectories cannot be precisely targeted, sacrificing the ability to follow predefined track lines allows for a significant reduction in power consumption and can eliminate the need for the expensive sensors and acoustic tracking needed for real-time localisation of RAI systems in the GPS deprived underwater environment. Furthermore, the increased mission duration eliminates the need for daily deployment and recovery using expensive crewed research vessels that put humans in high-risk situations and rapidly exceed the cost of even the most expensive robotic platforms.

To demonstrate this concept, this fellowship will develop a fleet of low-cost platforms that can maintain a desired altitude while obtaining 3D images of the seafloor. Each platform will cost < £5k and have an endurance of several weeks. Novel methods to reduce energy consumption will be developed. This includes a buoyancy control system that can achieve neutral buoyancy at any depth even in regions where the density of seawater is not precisely known. An intelligent, low-power 3D imaging system will be developed together with a hybrid altitude and illumination control system that minimises energy consumption. This will adapt both the frequency at which images are acquired and the strength of illumination used in order maintain a high-quality of data while minimising the amount of energy needed to control the platform's altitude. In order to determine the location of the seafloor images, a novel approach that combines; matched features between sequential images to estimate the motion between acquisitions; seafloor depth observations of all members in the fleet; information available about the terrain and the physics of regional scale flow, will be used to determine the most likely trajectories of each platform. The concepts developed in this research will be demonstrated through a series of experiments carried out under controlled conditions and during field trials using a small fleet of passive drifters that will be deployed at sea.

[1] C Roman et al., Lagrangian floats as seafloor imaging platforms, Continental Shelf Research 31, 1592-1598 (2011)

The challenges addressed by this proposal have a direct impact on the cost and availability of RAI systems to make detailed observations in extreme and hazardous underwater environments. This contributes to the UK's industrial strategy, which identifies RAI technologies in extreme environments as a challenge area for future sectors, and the goals of the EPSRC for building the resilience needed for a prosperous nation. The stakeholders that will directly and indirectly benefit beyond academia are; 1) industry e.g. developers, manufacturers, distributer and operators through economic gain and end users through the advance of knowledge, 2) regulators in government and private sectors through benefits to society, 3) wider public through benefit to society and the skills of people.

Wider public: On decadal timescales, sustaining seafloor environments and their ecosystems contributes to the economy and social well-being of the general public through job creation (e.g. sustaining industrial activity such as offshore resource development) and security (e.g. understanding the risks posed by global hazards such as climate change and pollution). On shorter timescales of < 5 years, the activities in this fellowship will developed experts with the necessary skill set to deliver impact to UK industry in the RAI sector through collaboration and technology transfer. This combined with outreach and public engagement will raise awareness of RAI systems and inspire future generations of RAI researchers.

Regulators: The growing recognition of human impacts on the environment (e.g. global warming, marine plastics and mining as discussed in recent intergovernmental G7 meetings) drives governments and industry to consider the best practices for sustained environmental monitoring. Building knowledge and understanding through monitoring the impact of industrial activities (e.g. offshore oil and gas extraction, fishing, mining, development of infrastructure and decommissioning) on seafloor ecosystems can help ground estimates of the socioeconomic costs associated with these activities, which in turn can help governments formulate informed and effective conservation and resource management policies over timescales of < 10 years. The cost of meeting the UK government's commitment to the conservation of marine protected areas and responsible decommissioning of offshore infrastructure is dependent on the technologies available for adoption to make observations over the necessary spatial and temporal scales. The application of the low-cost methods for long-term, regional-scale seafloor monitoring developed in this fellowship can contribute to this goal by enabling responsible monitoring at orders of magnitude lower cost than what is possible using today's technologies.

Industry and end-users: The requirement for regional scale monitoring drives industry and end-user investment in the development of technologies and best practises that can be widely adopted. End-users can benefit from these methods by advancing our knowledge and understanding of the impact of human activities on the environment. Industries in the supply chain stand to make economic gains by seeing the technologies they have invested in become widely adopted, both in the UK and globally. The investment in skills needed within the UK to deliver the UK's industrial strategy and the transfer of these skills to industry will lead to future innovations in the RAI sector and continued industrial impact.