How to Do a 3D Terrain Attitude Analysis with Ground Vehicles in STK

After creating your ground vehicle, inserting terrain, and designing your route, you may want to analyze how the movement along that terrain will affect your vehicle's attitude. By default, STK only analyzes attitude along the velocity vector of the vehicle. However, 3D analysis is also possible through the use of STK's Analysis Workbench. This article explains how to set up such an analysis, with the assumption that the route you defined is that of the right-most wheel. 

Create reference and destination points 

1. Open Analysis Workbench.
2. Select your ground vehicle under your object list and then click the icon for "Create new Point".
3. In the Add Geometry Component dialog box, select Fixed in System for Type, set the Fixed Point Type to Cartesian, set the Reference System to LVLH(CBF), and enter the width of your vehicle for Z.
4. Give the point a name and then click OK.
5. Create a another new point.
6. Select Surface for Type, select a central body, and select the previous point you just created as your Reference Point.
7. Be sure to select Terrain as your Reference Shape Type.
8. Give this new point a name and then click OK.

Create a displacement vector

1. Still in Analysis Workbench, click the icon for "Create new Vector".
2. Select Displacement for the Type.
3. Select the center of your ground vehicle for your Origin Point and the point you just created as your Destination Point.
4. Give the vector a name and then click OK.

Set the vehicle's properties

1. Now open your ground vehicle's properties and go to the Attitude page.
2. Make sure you are using Standard, and then for Type select Aligned and Constrained.
3. For your aligned vector's body, make sure the Type is Cartesian, X is set to 1, and Y and Z are set to 0.
4. For your reference vector, select your ground vehicle's Velocity(CBF) vector.
5. For the constrained vector, set the type to Cartesian, X to 0, Y to 1, and Z to 0.
6. For your vector, select the one you just created in Analysis Workbench. 
7. Click Apply but stay in the Ground Vehicle properties window.
8. Go to the 3D Graphics->Offsets page. Under Translational Offsets, enter half of your vehicle's width for the Y axis and click Apply.

Your ground vehicle's body axes will now adjust their angles based on the terrain.