The dynamic modelling and development of a controller for a general purpose remotely operated underwater vehicle

A preliminary mathematical model for the UCT SEAHOG Remotely operated underwater vehicle (ROV) is developed, including estimation of the rigid body, hydrodynamic and hydrostatic properties of the robot. A single state thruster model is developed and verified according to real life test data. A closed-loop speed controller is developed for the thruster module using a standard PI scheme and is implemented on an MSP430 microcontroller using software fixed-point algorithms. The complete ROV system is simulated in Simulink® in an open-loop configuration to gain insight into the expected motion from the vehicle. Controllers for depth and heading holding are designed using standard PID linearized control methods with gain scheduling and are then assessed within the complete system in a simulation environment. In addition, upgrades and maintenance are performed on the Power Pod, light and camera modules. Redesign, manufacture and testing of the SEAHOG junction box is performed, including a design solution to connect the tether power and fibre-optic lines at the surface and on the ROV. An extensive overhaul of the SEAHOG GUI is performed, utilising multicore processing architecture in LabVIEW and resulting in a user-orientated interface capable of controlling and monitoring all existing system data from the robot

Development and integration of a novel IP66 Force Feedback Joystick for offshore operations

Intervention activities in underwater environments are of great importance in many areas, such as the exploration, monitoring and documentation of sea resources, historical treasures or industrial applications. The use of robotic systems and automatic procedures is becoming fundamental, since the work conditions for divers are risky and often unfeasible, and several kind of works are every way impossible for humans. One of the most important objectives of the underwater robotic research consists in making technological systems friendly and easy to use by all kind of experts. This paper presents the development and test of a Force Feedback (FFB) Joystick aimed at supporting ROVs pilots during their work. Reaction forces on the joystick axes, based on specific error parameters, let the pilot understand in real-time the underwater environment where the robot is moving and thruster velocity saturation limits, thus improving significantly the efficiency of the given mission. The present work describes the design, assembly and programming of the joystick, and its test within a virtual environment simulating the real time control of Internet-enabled smart ROVs operating in remote locations. Results obtained with this kind of applications are discussed, and potentiality of the systems are underlined for future developments