Safety Aspects for Underwater Vehicles
Advances in technologies related to miniature sensors, memories, embedded controllers, power systems and materials has resulted in development of variety of autonomous underwater platforms for ocean exploration. The future in oceanographic instrumentation
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Abstract. Advances in technologies related to miniature sensors, memories, embedded controllers, power systems and materials has resulted in development of variety of autonomous underwater platforms for ocean exploration. The future in oceanographic instrumentation is intelligent small Autonomous Underwater Vehicles (AUV’s), autonomous profilers, gliders [1], etc. The ultimate aim in all autonomous platforms research and development is to reach the stage of unescorted missions with minimum failures. This stresses for implementation of multiple safety measures of a high degree so that the platform operates continuously in a fail-safe mode. This paper discusses issues on safety measures implemented on the autonomous underwater platforms namely MAYA AUV and the Autonomous Vertical Profiler [AVP] developed at NIO, Goa. The safety aspects in Design & Construction, Operations, Monitoring and Emergency have been addressed. Keywords: AUV, AVP, safety, collision.
1 Introduction AUVs are free-swimming marine robots that require little or no human intervention. They are compact self-contained low drag profile crafts powered (in most cases but not all) by a single underwater DC thruster and are used for surveys and applications in the horizontal plane. In contrast, the AVPs profile the vertical water column. These vehicles use on-board computers, power packs and vehicle payloads for automatic control, navigation and guidance [2]. They are equipped with state-of –the-art scientific sensors to measure oceanic properties, or specialized biological and chemical payloads to detect marine life. The advent of autonomous operations with underwater vehicles, high cost and reliability of these platforms has resulted in incorporation of multiple safety features.
2 Safety Multilayered safety needs to be incorporated from design stage in the hardware and software level of the vehicles. It is also essential that all safety measures are conceptualized at the initial design stage so as to incorporate the ideas in every sub system. These include: P. Vadakkepat et al. (Eds.): FIRA 2010, CCIS 103, pp. 10–16, 2010. © Springer-Verlag Berlin Heidelberg 2010
Safety Aspects for Underwater Vehicles
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safety at design & construction level operational safety monitoring health emergency systems
These safety aspects are discussed in succeeding pages. 2.1 Design and Construction The important issues in design& construction are the choice of materials and the sealing of static and dynamic ports [3]. These were addressed by: (a) Selecting the right wall thickness of the hull by way of using standard pressure housing design tables followed by verification using FEM analysis. (b) Confirming of material defects by performing non destructive tests before and after all machining (c) Adding a small positive buoyancy by using divinylcell foam (~50 to 200g positive in case of smaller vehicles) so as to ensure that the system floats in case of any electronics failure. Right choice and testing on the foam is critical in the design process to verify th
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