How to Attach a Compass to an Object in STK

Information

 
QuestionHow can I get reporting of my vehicle's direction?
Answer
To determine which way an object is pointing at any given time, you need to run a report on the object in you scenario. To simplify this, you can create a compass and attach it to an object. The compass will function as a real-time indicator of that object's direction.

Compass in STK

Here's how you do this:

1. Make a copy of your ground vehicle, ship, or aircraft.

2. If your STK object uses the Aviator propagator, follow the steps below. Otherwise, skip to step 3.
• Export an ephemeris file from your aircraft.  
• Change the propagator in the copy to STKExternal and load the *.e file you just created.

3. Rename your newly copied object "Compass."

4. Add a graphics model to Compass.
a. Download the NewCompass_Model zip folder attached to this article.
b. Open the Properties window of Compass and go to the 3D Graphics > Model tab.
c. In the Model section, make sure the Show check box is selected. Click the ellipsis button for Model File, browse to Compass_New.mdl in the downloaded zip folder, and click Open.

5. Scale the compass, if necessary, so that it fits around your vehicle.

6. The compass needs to be tangent to the Earth's surface and inertially fixed.
• Open the Compass' Properties window. In the Attitude tab, select Aligned and Constrained as the Type. For the Aligned Vector, set the Reference Vector to Nadir(Detic). For the Constrained Vector, set the Reference Vector to North. 

Compass Attitude

• To test the result, add a North vector to your original vehicle object. Do this in the vehicle's properties window by going to 3D Graphic > Vector and selecting the Show check box for the North Vector. It should be pointing to the red N on your compass.

7. Add a Velocity vector to your vehicle. In the Properties window, go to 3D Graphic > Vector and select the Show check box for the Velocity(CBF) Vector.

As you animate your scenario, the North vector will continue to point to the red N as the attitude and direction of your aircraft changes. The velocity vector is the needle of your compass.
TitleHow to Attach a Compass to an Object in STK
URL NameHow-to-attach-a-compass-to-an-object-in-STK

Related Files

NewCompass_Model.zip