QS BHD - Computation Settings

Take the following steps in order to check the most common settings in the computation.

In the Controller go to Computation Settings in the Settings Menu.

It is recommended to create a computation for each available positioning system. 
If the primary computation fails for some reason, e.g. a crash of the positioning system, the secondary computation is automatically promoted.

Click on Overview and make sure all the correct Objects and Sensors are enabled in each default computation.

Positioning systems defined in the template database are detected and a computation made for each one.
This is illustrated in the image below, i.e. NR203, C-NAV and Aquarius. 

If working with one or more anchor handling tugs make a separate computation for each of those objects.

Not applicable to backhoe dredging. 

Click on the name of a computation and check the Computation Priority list.

Click on the name of the positioning system and make this the computation Triggering System.

Make sure the correct Height Status is selected. As a rule of thumb, DGPS=Unreliable, RTK=Accurate.

When accurate height is selected the heights from the GPS receiver are used, overruling all height related components such as Tide and Draft. 
In most cases set the height to unreliable; Tide and Draft observations are then used in order to calculate the correct height. 
These settings will not affect the height of the dredge head.

Click on Dredge Models  to check the Dredge Head Model loaded.

To change the model, click on Import. See How-to Dredgehead Models.

Click on Steered Node   to set the Steered Node.

This node is used to compute 'along line' (dAlong) and 'across line' (dAcross) distances.

Select one node on each object to use as a Steered Node. Prioritize the objects to select the active Steered Node. 
In some cases dAlong and dAcross distances are referenced to the Spud CoG.

Select a vessel and then the Height tab in order to display all height related settings.

These settings are the same for all computations. In case multiple heave observations are available, a priority must be set.

Select whether or not to use Tide and if so what kind of Tide observation.

Select the Draft Parameters and choose the Draft Sensor to use.

Draft observations are filtered using a median filter, which takes the statistical median over all observations in the filter time period. You can modify the way the draft is calculated by changing the Draft settings. If all Sensors are set to Disabled then the Manual Draft value will be used. If at least one sensor is enabled then the manual value is not used but instead the sensor(s) will be used.

Select the Pseudo-USBL observation from the computation.

If the dredge tool is positioned three dimensionally by the Pseudo-USBL, enable the use of the Z Observation. If there is a depth sensor providing dredge tool depth, deselect the Z Observation from the Pseudo-USBL observation.

Draft is calculated in the Height Aiding Driver. Check the computed Draft value in the Height Aiding dialog.

A single Draft value valid for the CoG is calculated per object. Every QINSy heartbeat update (0.25 seconds) a new Draft value is calculated.

Proceed to: BHD - Session Setup.

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