A Fault-tolerant Free-vehicle Architecture for Hadal Zone Exploration

The usage of free vehicles (FV) in deep sea exploration has evolved during the last 75 years through different technologies. Hardened glass spheres have enabled contemporary vehicles that seamlessly combine housing, buoyancy, and full ocean depth deployment capability in simple structures that have opened the door to studying the extreme and remote environments of oceanic trenches (6,000m – 11,000m deep). However, sustained research efforts at these depths require reliable, highly autonomous, and robust free vehicle systems. In this paper we describe a custom designed fault tolerant FV architecture that incorporates a robust controller focusing on increased vehicle recoverability and consistent operation. We describe the approach followed to design the FV fault tolerant controller providing architectural details and results of functional tests in both a controlled lab environment and open sea trials that validate the design performance.