17 | Introduction
The system works according to the following process, which will be explained more thoroughly further on:
1. Motion Control determines which mode is used.
2. Normalize blocks convert sensor data to values between -1 and 1.
3. Position controller calculates the required thrust when positioned close to the target.
4. Velocity controller calculates required thrust when sailing to the target or along a track.
5. Gain is applied to the controller output. (not shown in system Diagram).
6. Vector Select checks for manual overrides from joystick or rotation knob.
7. Force calculation summarizes wind, waves, current and known external forces to total force demand.
8. Thruster Allocation routine determines the Set Point and direction of each thruster.
9. The thruster Ramps are applied, so that each thruster is increased or decreased to its ability.
10. Current is calculated from filtered thruster Set Points and speed of the vessel.
In the following chapters each of the processes in the system Diagram are explained in detail.
III.6.1 Motion Controller
The most important task of the Motion Controller is to change between modes:
•
Joystick Manual.
•
Joystick Auto (automatic heading control using bow thruster).
•
Auto Position (full automatic control).
•
Auto Pilot (automatic heading control using steering).
Note Due to Class requirements Auto Pilot is not available in DP system.
The Auto Position mode has several sub modes:
•
Tracking
•
ROV follow
The Motion Controller collects settings such as the Transfer speed and Rate Of Turn. Also the Motion Controller collects
sensor and position data. This data is passed on to the X, Y and Z controllers. The motion controller determines when
to change from velocity controlling to position controlling. For XY movements more than 15 meters Velocity Controller is
used. When the distance becomes less than 15 meters a combination of Position and Velocity controllers is used.
The Velocity Controller accelerates with a Deceleration / Acceleration setting of 0.05 meters / second.
For Z movements (rotation) the acceleration / deceleration is 1° / second and the system changes from positioning to
velocity when the heading distance is more than 30° from Set Point.
III.6.2 Normalize
The controller requires data scaled to values between range from -1 and +1.
Содержание Alphatron Marine AlphaDynaPos
Страница 1: ...AlphaDynaPos Ship Automation and Navigation system Operation Manual www jrc am ...
Страница 5: ...5 Contents 4 2 Appendix B Checklist for Taking DP system into Operation 85 ...
Страница 13: ...13 Introduction III 3 System Overview DP2 Figure 2 system Overview DP2 ...
Страница 14: ...14 Introduction III 4 Sensor Overview Figure 3 Sensor Overview ...
