Kongsberg cJoy OT, Руководство оператора

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System overview
• In the absence of position measurements, the model provides a “dead-reckoning”
mode. This means that the system is able to perform positioning for some time
without position updates from a position-reference system.
In the Kalman Filter, the Mathematical Vessel Model's reliability and the noise
level of the position measurement are the basis for deciding how much to trust each
measurement. As time elapses the model reliability will increase through continuous
updates from measured vessel response.
The process is adaptive. If, for example, the position-reference system is active and
it has a low update rate, the model reliability will decrease in the periods between
measurements, and the vessel model will therefore be heavily updated with each
measurement.
A Kalman Filter is also used for the heading information based on measurement from
the gyrocompass.
Additional advantages may be obtained by use of speed measurement. This can be used
as an addition to position measurements to improve the vessel speed control, and to make
calibration of position measurements faster when sailing at high speed.
A combination of speed measurement and a position-reference system will be better able
to handle dropout of position measurements during sailing (autopilot).
The speed measurement interface can be DGPS or Doppler Log.
The Controller
The controller calculates the resulting force to be exerted by the thrusters/propellers in
order for the vessel to remain on station.
The controller consists of the following parts:
• Excursion Feedback
The deviation between the operator-specified position/heading setpoints and the
actual position/heading data, and similar deviations with respect to the vessel's
velocity/heading rate, drive the excursion feedback. The deviations are multiplied
by gain factors to obtain a force demand (restoring demand and damping demand)
required to bring the vessel back to its setpoint values while also slowing down its
movements.
• Wind Feed-Forward
In order to counteract the wind forces as quickly as possible, the feed-forward concept
is used. Based on wind speed and direction measurements, the wind-induced forces
acting upon the vessel can be calculated. The thrusters/propellers are ordered to
counteract the forces due to wind.
•
Current Feedback
The excursion feedback and wind feed-forward are not sufficient to bring the vessel
back to the desired setpoints due to unmeasured external forces (such as waves
and current). The system estimates these forces over time, and calculates the force
demand required to counteract them.
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