A leader-follower synchronization output feedback control scheme is presented for the ship replenishment problem where only positions are measured. No mathematical model of the leader ship is required, and the control scheme relies on nonlinear observers to estimate velocity and acceleration of all ships to realize the feedback control law. The scheme yields semi-global uniform ultimate boundedness of the closed-loop errors. The bound is a function of the main ship acceleration, and under the assumption of zero main ship acceleration the closed-loop errors are semi-globally exponentially converging. The results are verified through experiments on a model-scale ship. r

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This paper presents a novel concept for remote inspection and maintenance operations on next generation normallyunmanned offshore oil platforms. The concept is presented through the design of a robotic lab facility for automated and teleoperated inspection and maintenance operations by robot manipulators -ranging from simple inspection tasks to advanced maintenance operations. The lab facility is built around two cooperating robot manipulators equipped with sensors measuring temperature, vibrations, gas concentration and sound, and that automatically changes between tools to operate valves, exchange batteries in wireless sensors and to manipulate objects and the integrated process equipment. A graphical interface allows users to start automated inspection rounds where sensor data are collected, analyzed and compared to normal operating conditions, and alarms are generated if deviations are detected. Users may also plan new operations in a virtual environment before executing them, or remotely control the robots through a number of control interfaces. Live video feeds and stereoscopic vision are available to aid the operator during remote operations. A model-based collision avoidance system ensures that both automated operations and unplanned operations are verified before and during execution, and ensures safe operation of the robots. The paper presents results from the lab facility to illustrate the functionality of the remote inspection and maintenance concept, and demonstrate how remote operators may start automatic inspection and maintenance operations, plan new operations in a virtual environment, or directly control the remote facility onshore.

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