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Dynamic positioning - basic principles
Forces and motions
Motion model - forces working on the ship
A seagoing vessel is subjected to forces from wind, waves and current as well as from forces generated by the propulsion system.
The vessel's response to these forces, i.e. its changes in position, heading and speed, is measured by the position-reference systems, the gyrocompass and the vertical reference sensors. Reference systems readings are corrected for roll and pitch
using readings from the vertical reference sensors. Wind speed and direction are measured by the wind sensors.
The K-Pos dynamic positioning control system calculates the forces that the thrusters must produce in order to control the vessel’s motion in three degrees of freedom - surge, sway and yaw - in the horizontal plane.
The K-Pos system is designed to keep the vessel within specified position and heading limits, and to minimise fuel consumption and wear and tear on the propulsion equipment. In addition, the K-Pos system tolerates transient errors in the measurement
systems and acts appropriately if a fault occurs in the thruster units.
Dynamic positioning system - Basic forces and motions