How do I model linear torque map powertrain for an electric powertrain to run tests like single and double lane change on motionview

Pramod Mallipudi

Hello,

I'm building a 3 wheeled (tadpole) vehicle for simulations such as constant radius turn, single and double lane change, etc. I've completed adding mass and inertia properties to all the systems and changing coordinates (front end of a car and rear end of a bike was selected from the templates and combined together). what do I change under the "linear torque map powertrain" system for the simulation with my powertrain parameters?  

Chris Coker_21312

Hi Pramod-

Some thoughts/suggestions, as I haven't tried this myself yet.

First, note that the "linear torque map powertrain" at a basic level, is really just a simple speed controller.  It doesn't really know if you are modeling an electric powertrain or an ICE powertrain.  We just need to make sure the range of torques are reasonable for the application.  So, as long as you are not doing a detailed study on the powertrain performance, this system should work well.

Next, as to modeling a hub motor, this is where the work comes in.  I would start by using the Linear Torque Map powertrain from the Car libraries, and not the two-wheeler libraries, as I think this will be easier to adapt.  Then, as a minimum, we need to change the "Differential Torque" Force, and how it is attached. This is the default setup from a car model:

For your model, since is a hub model it may look something like this:

Body 1 = Wheel/Hub

Body 2 = Knuckle (or swing arm, or frame, whatever the wheel is attached to)

Apply Force at:  Wheel Center

Local ref. frame:  A marker that defines the spin axis, probably one of the markers on the Rev joint where you attach the Wheel to the frame (or suspension)

 

Also note that in the Altair Driver attachments, you will also likely have to modify/fix the "Drive Joint" attachment.  This will likely just be the revolute joint for the wheel.  This is there to add a Motion at Time=0 to lock the driveline to achieve static eq.  However the AutoTire also is doing the same thing.  You may have to experiment a bit there to see what works.

 

Pramod Mallipudi

Thank you for your response sir. However, our powertrain doesn't have a hub motor...we plan on using a motor and drive the wheels using a shaft.

 

Chris Coker_21312

Pramod Mallipudi said:

Thank you for your response sir. However, our powertrain doesn't have a hub motor...we plan on using a motor and drive the wheels using a shaft.

 

Then you would model the powertrain in a similar fashion to what the default car libraries use.  Even simpler, as you'll likely have to do less modifications.