MotionSolve 2025.1: Vehicle ignores vertical profile (Z-axis) of 3D Spline Road in Roadcourse Event

Question

Hi Altair Community,

I'm currently running a vehicle dynamics simulation in Altair MotionView / MotionSolve 2025.1 using a Roadcourse Event. I am encountering an issue where the vehicle model does not track the vertical elevation (Z-axis) of the road profile, remaining completely flat throughout the simulation.

Here is my current setup:
-Vehicle Model: setup with MF-Tyre / MF-Swift (Delft Tyre) subsystem.
-Driver Path: Imported via a .csv file containing (X, Y, Z) coordinates, mapped to a 3D Cartesian Curve (DRIVE PATH).
-Road Profile: Configured as a 3D Spline Road (.rdf) using METHOD = '3D' and ROAD_TYPE = 'spline' inside the [XY_DATA] block with 96 discrete data points including non-zero Z elevations.

-Tire & Road Selection: The Road property file in both the Roadcourse entity and all 4 Tire subsystems are correctly pointed to this custom 3D Spline .rdf file.

The Problem:

At the initial simulation time (t = 0.00), the vehicle's tires are perfectly aligned and in contact with the start of the 3D road profile. However, as the simulation runs, the vehicle driver follows the horizontal path (X, Y) perfectly, but the vehicle completely ignores the vertical slopes. It drives straight through the elevated 3D road visualization, staying flat on the global ground level (Z = 0 or its initial height) while the road line climbs upward. The simulation finishes with a "Completed" status, but with incorrect vertical kinematics.

Troubleshooting Done So Far:
1. Verified that the Global Axis orientation is correct (Z-axis is the vertical/upward direction).

2. Switched from poly_line to spline method in the .rdf file to resolve the MF-Swift solver block parsing error.

3. Ensured that the initial position at t=0 is matched.

It seems like either the Roadcourse Driver controller is isolating tracking to the 2D top-down projection, or the MF-Swift tire model is not properly registering the 3D road mesh surface grid despite being assigned to the .rdf file.

Could anyone advise if there is a specific toggle in MotionView 2025.1 to force the Roadcourse Driver to include Vertical/Pitch tracking, or if there is a known limitation with MF-Swift handling user-defined 3D Spline roads in this version?

Thank you in advance for your support!

Orestis_YB · Accepted Answer

Hello @Sobree,

in the shared model I see that the rdf file is not set up in the way a MotionView one would be. I see there is some missing information in the blocks. In Sample Road Data Files you can see a template for the syntax. I'll try to update your file and let you know.

Hope this helps!

Best regards,

Orestes

Orestis_YB · Accepted Answer

Hello @Sobree,

here is a modified file of the rdf. I used meters in my case so I just quickly changed the decimal point in a text editor. Something worth mentioning is that your curve graphic has as reference point the global origin I would recommend to use the front road reference point of the road within Auto Tires system. Also you may see some solver crash if you use it as is. This is because of the static. A tip when you see situations like this is to move the road reference point towards the tire so there is a slight penetration. Myself I just added 50mm to front and rear point.

test.zip

I did run the simulation, and the vehicle is now climbing uphill as it should.

Hope this helps!

Best regards,

Orestes