Design of a communications link for an ROV

Abstract

Remotely Operated Vehicles (ROVs) have enabled a wide range of applications spanning from underwater surveillance to maintenance and repair. From an engineering perspective, the design of such vehicles is governed by underwater physical conditions including elevated surrounding pressures, weak electromagnetic penetration depths and increased vehicle drag. In this dissertation, the design and preliminary implementation of an underwater ROV system is presented. This includes a mathematical model that enables prediction of underwater trajectories, empirical characterisation of generated thrust values and an electronic system that enables bi-directional exchange of data between the ROV and remote operator, navigation command inputs, propeller actuation and sensor interfacing. The link uses a fibre optic tether cable that allows an exchange of navigation commands and underwater sensor measurements. The testing of the electronic system showed that the navigation commands originating from the operator can be efficiently transmitted to the ROV over a single communications channel. In terms of performance, the results indicate that increasing the transmission rates beyond certain thresholds will reduce the robustness of the link.