part 2 : DYNAMIC POSITIONING SYSTEM

DYNAMIC POSITIONING SYSTEM

This system offer a full range of dynamic positioning systems to keep the vessel within specified position and heading limits. These systems are designed to minimise fuel consumption and wear and tear on the propulsion equipment. The K-Pos operator station is available in single, dual or triple configurations. More than 1200 dynamic positioning - DP systems have been supplied to oil and gas related vessels.
Typical applications for dynamic positioning systems

* Drill ships
* Cable-laying vessels
* Crane vessels
* Cruise ships
* Diving support vessels
* Dredging
* FPSO's
* Flotels
* Maritime research vessels



* Mega yachts
* Mine sweepers
* Pipe laying vessels
* Platform supply vessels
* Rock dumping vessels
* Survey ships
* Supply vessels
* Shuttle tankers

The dynamic positioning systems controller

The dynamic positioning systems controller calculates the resulting force to be exerted by the thrusters/propellers in order for the vessel to remain on station. In station-keeping operations, the K-Pos Controller can be working in several of the following modes, all with special characteristics:

High Precision control: The High Precision dynamic positioning systems control provides high accuracy station-keeping in any weather condition at the expense of power consumption and exposure to wear and tear of machinery and thrusters.

Relaxed control: The Relaxed dynamic positioning systems control uses the thrusters more smoothly, at the expense of station-keeping accuracy. However, this type of control cannot guarantee that the vessel will stay within its operational area, and is mainly applicable for calm weather conditions.

Green DP® control: The Green DP® dynamic positioning systems control uses very different control technology, called non-linear Model Predictive Control, which is optimised for precise area keeping with minimum power consumption. The Green DP® control is applicable in all weather conditions. The transition between K-Pos dynamic positioning system controller modes is bumpless.
Stand alone or integrated systems

* Stand-alone dynamic positioning systems interface with other systems, such as power plant and thrusters, via conventional signal cables and serial lines
* Integrated dynamic positioning systems communicate with other KONGSBERG systems such as K-Chief (Marine Automation) and K-Thrust (Thruster Control) via a dual Ethernet LAN

Basic forces and motions

A seagoing vessel is subject to the forces of wind, waves and current and those generated by the propulsion system. In a dynamic positioning system the response to these forces in terms of changes in position, heading and speed, are measured by position-reference systems, gyrocompass and vertical reference sensors. The dynamic positioning system calculates the forces that the thrusters must produce in order to control the vessel's motion.

A ship is considered to have six degrees of freedom in its motion. Three of these involve translation:

* Surge (forward / astern)
* Sway (starboard / port)
* Heave (up / down)

The other three are rotation:

* Roll (rotation about surge axis)
* Pitch (rotation about sway axis)
* Yaw (rotation about heave axis)

Dynamic positioning - DP systems are concerned primarily with control of the ship in the horizontal plane, i.e. the three axes surge, sway and yaw.

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