GENERIC CONTROL OF MOBILE ROBOTS IN UNDERWATER ENVIRONMENT FOR ADVANCED OFFSHORE AUTOMATIC OPERATIONS – CONGRE

This project aims to develop new decision-making technologies for AUVs (Autonomous Underwater Vehicles) of the future. An important motivation of the project is drawn from the fact that current AUV technologies are still considered immature for the realization on a daily-routine basis of offshore operations, such as inspection and surveillance of infrastructure, oilfield monitoring, etc. Industrially accepted and widely used methods for these tasks are still based on the use of a ROV (Remotely Operated Vehicle) deployed from a surface ship and at least one pilot throughout the mission. These operations are costly and very complex, especially in deep sea and/or in the presence of obstacles. There are numerous difficulties to overcome in order to control the AUVs safely and efficiently. These difficulties are related to the limitations of actuation power with respect to disturbances and changes in navigation modes, the high imprecisions on the hydrodynamic models available, the unpredictable nature of the sea current and the difficulty of accurately measuring or estimating the quantities required for control implementation. To these difficulties, are added the highly nonlinear character of the equations of motion of the AUVs, the underactuation nature of these vehicles caused by the loss of efficiency of certain actuators from one operation mode to another (from fully-actuated mode to underactuated mode or from an underactuated mode to another), the complexity inherent to underwater environment of the information provided by the exteroceptive sensors, and finally the diversity of platforms dictated by the growing needs of the offshore industry.

The objective of the project is to establish a new control paradigm for underwater vehicles that integrates in a unified and elegant framework the procedures of modeling, control, estimation and optimization. At the heart of this new methodology is the judicious exploitation of the main hydrodynamic forces in control design for a large class of autonomous underwater vehicles typically underactuated (gliders, propelled or hybrids), resulting in a simple, but fast and inexpensive approach that improves navigation ability and increases performance and application areas. More specifically, the project aims to propose new nonlinear control and sensor-based control techniques via an adapted modeling procedure that requires simple empirical calculations instead of heavy and expensive identifications. The experiments, however, require implementation of the developed control laws, thus involving the development of nonlinear observers adapted to the tasks assigned to the vehicles such as inspection and surveillance operations. Envisioned sea trials will undoubtedly convince the specialized community.

The involvement of ALSEAMAR through their expertise, their means of experimentation and their geographical location (located between the two other project partners -LIRMM and I3S-) is a definite asset that will allow for the development of the project to be coherently shared between theoretical developments (with potential application developments) and technological and applied developments.