EACS 2016 paper - Control Strategies for an Underwater Geotechnical Drilling System

Submarine geotechnical exploration is a challenging task that is experiencing a paradigm shift due to the application of robotics and automation to (until now) traditional drilling procedures. The MD500 Project is an underwater subsea geotechnical drilling and in situ testing device developed with the goal of retrieving high-quality physical samples of the seabed at study depths of up to 150 m and with a nominal water depth of 500 m. The system applications range in areas of marine activity, such as: port infrastructure, nearshore and offshore, renewable energy projects at sea, oil & gas, mining etc.
The machine is composed of a set of remotely operated devices that must synchronize with each other: drilling rig, stabilizing legs and three manipulators two cartesian robots and one anthropomorphic robot arm. These manipulators can be operated either manually or in a semiautomated mode. The automated routines aim to substitute the actions of the technicians when handling the tubes and rods in the harsh environment for which the machine is envisioned, allowing the operator to focus on the drilling process (which can be semi-automated as well). Some other benefits that can be obtained by automating the processes are reduction in cycle times and increased repeatability —which leads to higher efficiency rates since the cycle times are more consistent and can be predicted more accurately. All these advantages lead to a reduction of the overall operation cost.
In order to accurately control the position of the electro-hydraulic motion systems a set of Fuzzy-Adaptive PID (proportional-integral-derivative) controllers is implemented. The paper presents an overview of the control loops implementation, performance assessment, distributed control network architecture and the logic behind the tool manipulation and the handling sequences and routines of the MD500.