Poster Abstract: Hybrid Underwater Environmental Monitoring

Many underwater monitoring tasks, such as submarine life studies and pipeline inspections, are usually performed manually. Automated underwater monitoring has the potential to increase safety, improve timeliness, and decrease costs. We propose a hybrid solution of stationary sensor buoys and swarms of autonomous underwater vehicles (AUV) and report on our current progress of its realization. Our solution is based on sensor network technology and a small mobile underwater robot developed in our institute. Christian Renner and Benjamin Meyer and Daniel Bimschas and Alexander Gabrecht and Sebastian Ebers and Thomas Tosik and Ammar Amory and Erik Maehle and Stefan Fischer. Poster Abstract: Hybrid Underwater Environmental Monitoring. In Proceedings of the 12th ACM Conference on Embedded Networked Sensor Systems, SenSys ’14, Memphis, TN, USA, November 2014. c © held by the authors, 2014. This is the authors’ version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in Proceedings of the 12th ACM Conference on Embedded Networked Sensor Systems, http://dx.doi.org/10.1145/2668332.2668354. 1 Motivation Recent advances in electronics and robotics—particularly in the context of low-power sensor networks and small mobile underwater robots—enable automated and potentially unsupervised environmental underwater inshore monitoring. Among the practical applications are water quality monitoring, structural monitoring, and the study of marine life [1]. In this application field, a hybrid solution embracing stationary sensor buoys and swarms of autonomous underwater vehicles (AUV) and autonomous surface vehicles (ASV) offer a monitoring solution that is flexible, cost-efficient, reusable, and self-organizing. The stationary, sparse network of sensor buoys in the area of interest enables a rudimentary, coarse-grained but cheap, timely, and almost non-invasive monitoring facility. The buoys report their sensor readings to a base station via, e.g., GPRS. The detection of unusual events—e.g., poor water quality close to a pipeline—triggers the activation of the swarm of AUVs and ASVs, which set off to explore the area in more detail and find the source of contamination, e.g., the pipeline leakage. In this paper, we perform a feasibility analysis regarding the realization of such a flexible, hybrid underwater monitoring platform. In Sec. 2, we discuss the requirements of Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for third-party components of this work must be honored. For all other uses, contact the Owner/Author. Copyright is held by the owner/author(s). SenSys’14, November 3–5, 2014, Memphis, TN, USA. ACM 978-1-4503-3143-2/14/11. http://dx.doi.org/10.1145/2668332.2668354 typical environmental underwater monitoring scenarios and devise a suitable system architecture in Sec. 3. Here, we outline our current progress with the development of low-power, low-cost AUVs and ASVs connected with a low-cost, lowpower acoustic modem. We also study the feasibility of using typical sensor nodes to realize sensor buoys and discuss the exploitation of regenerative energy sources. 2 Requirement Analysis Targeting the application scenarios outlined in Sec. 1, the following requirements must be met for their successful realization w.r.t. economic and sustainable success: • low unit cost for economical advantages, • tiny form factor to allow for non-intrusive monitoring, • low power consumption to achieve perpetual operation of sensor buoys and long swarm mission times, • flexibility to permit application-specific modifications, • localization for swarm interaction and positioning, • fast response times for swarm coordination tasks, • robustness against damage and faulty behavior. Current underwater vehicles, sensor capsules, and longrange communication hardware mainly aim at deep-water applications, such as trans-continental pipeline or cable monitoring and search-and-rescue missions after ship or airplane accidents. To fit the needs of deep-water scenarios, these appliances are particularly pressure-resistant and robust. Therefore, they come at high unit costs, have large dimensions, and a relatively high power consumption. The mission time of such underwater vehicles is hence limited to a few hours of operation under manual control with a low number, usually being one, of vehicles. Stationary sensors, in contrast, may achieve longer operation time yet suffer from low spatial resolution due to their unit cost. Particularly due to their size and unit cost, both cannot be employed for cost-sensitive inshore scenarios—e.g., the observation of limnic eruptions, structural monitoring, harbor inspections, and aquaculture monitoring—or coastal monitoring. 3 System Architecture Our goal is to enable fine-grained, precise, yet nonintrusive monitoring in inshore and coastal scenarios at a low price point. To meet these contradicting demands, we envision a system architecture as shown in Fig. 1 comprising Figure 1. Schematic collaboration between MONSUN AUVs with stationary sensor buoys in a pipeline monitoring application. Edges indicate communication links. • stationary sensor buoys equipped with a minimal sensor configuration and communication facilities and • mobile, autonomous underwater and surface vehicles with high-precision sensors and acoustic communication devices for swarm communication.