Calculating Self Aligning Torque?

Question

Hey,

As there is no suspension geometry in VPP, what is a good way of calculating steering wheels self-aligning torque? Typically values from the suspension configuration are used like Kingpin Inclination, Mechanical Trail, Pneumatic Trail etc...

If the only solution is to implement my own suspension setup, how would you advise that I do that in a way that will cause the least friction to swap out when VPP natively supports suspension like this?

Cheers,

Tim

Answer 1

VPP exposes these parameters in WheelState:

• WheelState.suspensionCompression. Ratio of compression of the suspension. 0.0 is fully elongated (wheel in the air), 1.0 is fully compressed (hitting the bump stops). 
• WheelState.steerAngle. Angle in degrees of the wheel with respect to the longitudinal axis of the vehicle. Steering and TOE modify this angle.
• WheelState.verticalLoad. The vertical force directly applied on the contact patch.

You may write your own add-on component to define and configure the geometry of a complex suspension system. Use suspensionCompression and steerAngle to calculate the actual hypothetical state of the wheel (camber, caster, etc) in that geometry. Combined with verticalLoad, you could  then calculate the self-aligning torque out of that.

When VPP supports complex suspension geometries the new states of the wheel  (camber, caster...) will be exposed in WheelState so you could remove your calculations for these. Eventually, a self-alignment torque value will be calculated and exposed as well.

WheelState reference:
https://vehiclephysics.com/advanced/vehiclebase-reference/#nested-classes

Example code of accessing WheelState members:
https://vehiclephysics.com/advanced/custom-addons/#example-source-code

Comments

Thanks, I'll start implementing some suspension geometry then :p