Funding: French Research and Industry Ministry Grant 2022-2025
E-mail: Martin-filliung (at) etud.univ-tln.fr
Office: Building M, University of Toulon, Campus La Garde.
Thesis director: Nicolas Boizot (CNRS LIS Laboratory), HDR lecturer,
Supervisor : Claire Dune (COSMER Laboratory), Associate Professor.
Title: control of a rope of underwater robots
Recent advances in embedded technologies, the miniaturization of sensors and the decrease of their costs have accelerated the development of mini underwater drones. Despite the loss of performance compared to current operational devices, their low weight and size are interesting because they can be deployed by a single person from small boats without expensive and cumbersome launching or recovery systems, which would require large vessels and a full crew.
The cable that connects the ROV to the boat at the surface is still the only way to communicate a significant amount of information underwater, as electromagnetic waves are absorbed within the first few centimeters. While for large industrial ROVs, of the working class type, the drag of the umbilical is easily countered by the mass and engine power of the system, this is no longer the case when considering small, low-cost devices. This is even more true when you move away from the boat and approach the coastal zone called surf zone with strong current and swell. However, this is the destination zone for these mini-robots that can evolve in shallow water. Their mission therefore requires them to be particularly exposed to marine disturbances. In order to help a mini-ROV to counter the disturbances of its umbilical, the COSMER laboratory is working on the concept of robot ropes. The idea is to add mini-ROVs regularly on the umbilical so that they erase in a coordinated way the disturbances of the cable on the leading robot. This also allows to position the cable in space taking into account the obstacles and to avoid that it gets tangled in the systems or on itself.
This thesis is therefore in line with one of the mobile robotics themes of the COSMER laboratory, namely taking into account the influence of the umbilical on the maneuvering of a light ROV.
The objective is to propose a control that takes into account the specific dynamics of the rope, including a modeling of the dynamics of the gear and the dynamics of the rope by damping the effects of platooning (accordion effect of the trains of vehicles) and rejecting external disturbances, such as currents in the body of water (see for example the catenary robot).
We will place ourselves at the intersection of robotics and control theory. The implementation of adaptive techniques, or techniques related to reinforcement learning may also be considered.