HydroLaunch

Dept. of Engineering Cybernetics Professor Thor I. Fossen (head of project) Professor Olav Egeland Professor Tor Arne Johansen Post. Doc. Bjørnar Vik

Norsk Hydro Produksjon Professor II Svein Ivar Sagatun (project coordinator) Professor II Finn Gunnar Nielsen

Control System Design for Crane-Moonpool Operations

A floating vessel scale 1:30 has been constructed in cooperation with Norsk Hydro AS. The vessel is equipped with a crane for offshore moonpool operations. The winch is controlled by using an 2.2 kW asynchronous motor. A winch control system with heave compensation and wave synchronization have been developed and tested experimentally in the MCLab for regular waves and iregular waves (JONSWAP spectrum). For optimal wire tension in air, heave compensation is implemented using feedforward from the body-fixed heave acceleration. Before and during water entry the payload motion is synchronized with the moonpool wave amplitude. This reduces wire tension with up to 50% depending on the sea state. The control system is implemented under Matlab/Simulink using the QNX real-time operating system and OPAL. The concept of wave synchronization is shown on video and in the reports below:

Video showing wave synchronization     [mov][wmv][divx -- Download DivX plug in] Pictures of Equipment and Experimental Set-Up Experimental Results and Matlab Data Files Reports and Publications Main Data Lpp B T D Total mass Deplasement Ix Iy Iz Buoyancy KG BG GM_T GM_L Heave period Roll period Pitch period Moonpool period Model (Scale 1:30) 1.10 (m) 0.67 (m) 0.30 (m) 0.44 (m) 188.43 (kg) 0.19 (m^3) 6.98 (kg m^2) 29.14 (kg m^2) 14.42 (kg m^2) 1848 (N) 0.24 (m) 0.09 (m) 0.05 (m) 0.30 (m) 1.74 (s) 1.84 (s) 1.52 (s) 1.10 (s) Full Scale 33.0 (m) 20.1 (m) 9.0(m) 13.2 (m) 5087.6 (tonnes) 5088.0 (m^3) 169643935 (kg m^2) 708081301 (kg m^2) 350329866 (kg m^2) 49909454 (N) 7.3 (m) 2.8 (m) 1.5 (m) 8.9 (m) 9.5 (s) 10.1 (s) 8.3 (s) 6.0 (s)

Pay Loads: < 540 tonnes Pay Load (Scale 1:30): < 20 kg

Crane-Vessel with Payload The figure shows the crane mounted on top of a floating vessel. Accelerometers are located inside the payload and on the top of the vessel. A motor controlled winch with encoder feedback is used to control the payload position. The goal is to minimize wave loads when lifting the payload through the wave zone. This is achieved through wave synchronization.