Design and Development of AUVs for cooperative missions

In project Small Team of Autonomous Robotic Fish (STARFISH), we are building a team of lowcost Autonomous Underwater Vehicles (AUVs), each with different capabilities and being able to accomplish a particular mission collectively by sharing information. A team of AUVs has distinct advantages over a single complex AUV in terms of fault tolerance, redundancy, simultaneous multipoint spatial sampling, and better overall communications to mother-ship. Data from multiple AUVs are fused to perform localization and navigation and eliminate the need for expensive navigational equipment on each AUV. Command and control is done in a distributed fashion. Underlying this team behaviour is a robust networked communications system which primarily uses locally developed highly optimized modems underwater and radio communication when on the surface. AUV test platforms allowing us complete autonomy over their design specifications and control were required to constitute this team. Existing AUV competency from the open literature along with novel ideas have been incorporated to achieve the final design of our AUVs. The entire AUV has been designed to be modular from a mechanical, electrical and software perspective so that additional, payloads such as Doppler Velocity Log (DVL), Conductivity-Temperature-Turbidity-Depth (CTD), Side-scan etc. can be included with ease. Standard electrical interface between modules offers the required flexibility in terms of development of additional modules. Additional sections can be included without affecting the final design provided they are self sufficient in terms of battery life and neutrally buoyant. These AUVs will serve as a test platform to demonstrate cooperative behaviour which would enable us to perform complex tasks such as surveying, tracking and target re-acquisition effectively along with the testing and development for the allied technologies such as localisation, positioning, control etc that are required for cooperative behaviour. Group behavioural aspects along with the design details of such AUVs are presented in this paper.