General HydroStatics
Ship Stability Software
Command of the Week
(New or interesting aspects of GHS that you may not know about)

Sensor Interface (SI)
(Requires GHS/GLM with LEw, SI)

When GHS Load Monitor (GLM) is used aboard ship, the Sensor Interface module makes tank sensor information available to the computer model. Whether by sounding, ullage, pressure, or volume, tank level information is picked up and used to set tank loads. Additionally, fluid density can be received.

In the image below the tanks that are connected via the Sensor Interface are distinguished by color and the ~ character. These tanks are controlled by the information coming in through a channel that is presumably fed by sensors in real tanks.

Draft sensors can be interfaced as well, as the example below (which is a very simple case with only a few tanks represented) shows. Trim and heel angle inclinometers can be interfaced also. Unlike tank levels which directly affect the state of the simulation, draft, trim, and heel angles are advisory. The Draft from sensors box shown below is preliminary to a "Verify" screen which helps the operator resolve differences in the state of the model vs. the real ship.

Below is a sample of the setup dialog where tanks are assigned to particular sensor ID codes. More than two draft sensors can be interfaced, enabling it to derive heel as well as draft and trim. (By the way, if more than two sensor inputs come from the same tank, they are averaged—or the operator can take one of them off line via the Sensor Interface if one is giving faulty information.)

Additional functions for which inputs are defined are the crane parameters: azimuth, elevation, knuckle angle, hook number, hook load, and crane number. Thus the cranes in the model can be controlled by actual crane positions and loads.

Of course any or all of the sensor inputs can be disabled so that the model is free to be used for exploring conditions that differ from the current state of the vessel.

The image below is of the opening dialog of the SI module with the drop-down list showing the various protocols that are currently supported.

Note that more than one system can be interfaced simultaneously. This is to accommodate multiple types of sensor hardware. For example, one protocol may be used for the tank gauging and another for the crane information.

The SI main dialog is a compact thing that you can position anywhere on the computer screen. It provides tools for checking the data being received. The image below shows the tool for examining the inputs received from specified tanks. Note the Sent and Density columns which are not used in this example. (Volume calculated by the model can be sent back through the sensor system.)

The image below shows another tool by which any sensor can be checked, whether it is for tank level, draft, trim, heel, or crane information. Another dialog (not shown here) allows the operator to disconnect individual sensor inputs from the model.

If you are a long-time user of GHS, you may remember that early versions of the manual noted that we were working on getting it to the point where it could make coffee. Regardless of what the shipboard guys may think, the SI module is a step in that direction. We want you to be awake to every opportunity to configure and install GLM on any floating object you have anything to do with. Get them to instrument their tanks if need be, and make them get rid of those spreadsheets!

Questions, comments, or requests?
Contact Creative Systems, Inc.

USA phone: 360-385-6212 Fax: 360-385-6213
Office hours: 7:00 am - 4:00 pm Pacific Time, Monday - Friday

Mailing address:
PO Box 1910
Port Townsend, WA 98368 USA

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