The CutterSuction Tool driver calculates a relative X, Y, and Z between two objects, a vessel (or ROV) and a CutterSuction head.
It is not a real USBL system, but actually a pseudo USBL system.
It receives, via an A/D converter, vertical and/or horizontal angles.
The driver has a user-interface to enter the range between the 'from' object node and the 'to' object node, (C-O) values, input units (and limits) and angle computation mode.
The driver will use the slant range and the two angles to calculate the pseudo USBL dX, dY and dZ values.
Presently, only the VanDerLeun format is supported (Installatiebouw Van Der Leun, Sliedrecht, Nederland).
The VanDerLeun A/D converter sends four ASCII strings, containing vessel depth or draft ("inzinking"), vertical angle ("hoek ladder"), and two dummy strings which can be used for future driver extensions.
The values that are obtained from the input data strings, as well as the values used to compute the dX, dY, dZ values and the computed dX, dY, dZ values are shown in the driver window.
When a value does not update, for example a depth reading "NO SIGN", then the box is empty. In this case, the old input value is retained, but the quality indicator of the observation is set to -1, as can be seen in an Observation Physics Display.
To compute dX, dY and dZ observations, create an new object, e.g. "Suction Head"; this will automatically add a reference node, which will be the "USBL target transponder".
Subsequently, add a "USBL" system, select the driver "CutterSuction Tool format (dX, dY, dZ)", and set the appropriate serial RS232 parameters.
On the USBL Parameters tab sheet, the Location should be the node at which the angles are measured.
Set the Sign convention for Z-axis data to positive downward if vertical angles are measured positive downward. Set all alignments to "No".
Set the Alignment corrections to 0, if input data limits are to be defined in the driver.
Skip the Administrative Records tab sheet.
On the Targets tab sheet, select the suction head reference node.
In order to decode (also) the depth measurement, add a system of type Underwater sensor to the object on which the depth sensor is located.
Select the "CutterSuction Tool VanderLeun" driver and interface parameters as with the USBL system.
Press the "Next" button to continue the setup.
Select the object and press the "Add" button to add an observation of type "ROV depth" to the system.
Define a new "At Node" if necessary. Press "OK" to save the observation.
Press "Next" button, select Depth Observation and enter the appropriate unit.
"Apply Properties to Observation" and "Finish" the system setup.
First time online, restore the "Cutter Tool Driver" window, visible on the Windows taskbar, and press "Settings..." button to define the driver's decoding and computation properties.
Make sure to define ranges and equivalents for "Angle Limits" and/or "Depth Limits" if input data value units are volts or (milli)amperes.
Be sure to add the Cutter Tool USBL system to a computation in order to position the suction head node(s).
The depth observation can be used in the computation as "ROV" depth, to compute relative heights with respect to the water level.
A vertical height difference between this water level and the survey datum should be entered as geoidal separation or tide value.
Drivers IO Notes
Command line parameters in "drivers.io" file are used to indicate the format, e.g. "VDL" for VanDerLeun format, and data string to trigger a driver update, e.g. "A02" to compute and send USBL data to Qinsy.