How to define a multi-stage (ramp-up then constant) velocity profile for a Constant-Radius Cornering

Sobree

Hi everyone,
I am currently running a vehicle dynamics simulation in Altair MotionView 2025.1 .
I am setting up a Constant-Radius Cornering Event.

By default, the event only provides Initial Velocity and Final Velocity inputs, which creates a continuous linear acceleration (ramp up) throughout the entire simulation time.

However, my goal is to create a 3-stage velocity profile: (In this picture red line)

1. Stage 1: Linear acceleration (Ramp-up) from the initial speed.
2. Stage 2: Sharp transition/bend when reaching the target speed (around 4,166 mm/s).
3. Stage 3: Maintain a strictly constant speed (horizontal flat line) for the rest of the simulation.

I previously tried modifying the Driver Throttle Output (sv_throttle_output) from Linear to Curve and Expression (using the AKIMA function referencing a custom time-vs-velocity curve).
However, this caused a math parser error during the solver run because the vehicle's powertrain logic explicitly relies on the default VARVAL of the throttle output variable.

Could anyone please guide me on the correct or best practice way to implement this kind of multi-stage velocity profile within the Altair Driver / Constant-Radius event without breaking the powertrain system equations?

Thank you in advance for your help!

GTT Adam

Hi @Sobree,

When looking to modify standard events, you can first run a standard event to generate the ADF file (Altair Driver File). This is the set of commands the Driver Model receives for how and when to initiate different maneuvers. If we look at the default Constant Radius Event, the ADF will feature headers for the initial conditions and then a maneuvers list:

You can add as many maneuvers to this ADM as you wish to create you own series of events. Use the default as a template and add more maneuvers to the list and then the details for the maneuvers below.

When complete, add a new event to your model called the DriverFile event:

Here you can then select the custom ADF file and deploy you own custom events.

For more on the Altair Driver File, please use the following link:

https://help.altair.com/hwdesktop/hwx/topics/chapter_heads/full_vehicles_with_driver_r.htm

Hope this helps!

Adam Reid