Scale vehicle support

Question

How well will VPP handle vehicles significantly different scales than full-sized ones? I'm specifically interested in using VPP for an offroad RC racing sim. To give some ballpark numbers, a typical vehicle would have a wheel base of 0.3m, weigh a couple of KG, have a 3 HP engine, and max speed of around 80 KPH (though 50 KPH is more realistic to hit during a race).

If the physics holds up/scales OK, might the WheelCollider cause issues? From what I've read about Unity's WC, it sounds like it isn't really suitable for an offroad sim. Is it possible to switch VPP from using Unity's built-in WC to another from the Asset Store?

Answer 1

I haven't tried such tiny cars, but I think they should work in VPP. The smallest vehicle I've  tried so far weights 10 Kg.

Follow these rules in small vehicles:

• The GameObjects related with physics (Rigidbody, WheelCollider, joints) should always have Scale = 1,1,1 in their Transform and all their ancestors.
• Put the visual mesh in a child GameObject. You may apply scale here if needed.
• The car's convex Colliders may also receive a scale different than 1.
• Use scaled mass and scaled physic magnitudes everywhere: rigidbody, springs, dampers, engine torque and rpms, etc.
• Instabilities may be mitigated by increasing the inertia magnitudes in Vehicle Controller > Inertia (use Parametric mode).
• Consider increasing the physics simulation rate in Unity as much as possible. For a 1:10 scale, the physics rate should be 500 Hz (50 Hz / 0.1) to achieve the same level of detail and realism of full size cars.

VPP has some limits in some parameters that might be an issue:

• Minimum engine inertia is 0.01.
• Minimum suspension spring rate is 1 N/m.

Not sure if RC cars require smaller values. Anyways, please let me know if you encounter any issues configuring them and I'll try to help.

Comments

Edit 2024: The latest developments in VPP (currently Alpha) discarded the Unity's WheelCollider and include new wheel collision components with many new features.