ABSTRACT
This chapter begins with an introduction to the six degrees of movement that a free-floating vessel/object is subjected to while at sea. It is important for a DP professional to understand these movements, as out of these six, the three movements must be controlled to ensure that the vessel stays in position.
The movements are divided into two planes, vertical and horizontal. The movements on the horizontal plane must be measured and controlled. The degrees of movement which are on the vertical plane are measured but not controlled. How these are measured and the arrangements made to control them is explained well in easy language. The chapter also covers the important aspects like mathematical model, wind feed forward, DP current or residual as current, model control or dead reckoning and Kalman filter. The chapter also includes the steps to put the vessel into auto position mode wherein the vessel is completely under the control of the computer and maintains her position automatically by using active thrust.
