Vehicle rigging notes
These are my own notes for rigging vehicles. Currently adapted to rigging trucks, as I've had to rig quite a few of these recently.
- Total weight
- Weight per axle
- Engine specs and engine curve
- Transmission type, gears, gear ratios
- Axle ratio / Final ratio
- Top speed
Main GameObject + child mesh + child collider
Rigidbody: Total weight
VPVehicleController, VPTelemetry, VPStandardInput
- Child WheelColliders GameObject with one VPWheelCollider child per wheel.
- Specify wheel meshes in VPWheelCollider.
- Align VPWheelColliders with meshes. Verify alignment.
- Spring: mass * g * 8 / number of wheels
- Damper: spring / 20
- Configure wheels in VPVehicleController > Axles
Center of Mass (CoM)
- Child GameObject, reference it in VPVehicleController > Center Of Mass
- Longitudinal position: use weight per axle from specifications.
- Preliminary: must be refined after configuring suspension.
- Differential: Final Ratio
- Max Steer Angle: Turn radius
- Ackerman: child GameObject approx. in the position of the rear axle. Reference it in VPVehicleController > Steering > Ackerman Reference
- Trucks: ~12000, 0.6. Parking: ~15000, 0.5
Tires (Parametric Model)
Single truck wheels:
Adherent: 0.5, 0.8 Peak: 1.6, 0.9 Limit: 8, 0.7 ABCD: 0.6, 0, 0.2, 0
Twin truck wheels (use VPTireFrictionModifier):
Adherent: 0.5, 0,9 Peak: 1.8, 1.1 Limit: 8, 0.9 ABCD: 0.8, 0, 0.15, 0
- Engine curves and specs
- Gear ratios
- Gear up/down rpms, manual y automatic transmissions
- 12 substeps
- Trucks: Tire Impulse Ratio: 0.3-0.4
- Trucks: Engine Reaction Factor: 0.9
- Audio: add Truck Audio or Car Audio prefabs
- Visual effects
Suspension and dynamics
- Must support max weight per axle
- Traction trucks: test for max load over fifth wheel
- Anti-roll bars
- Progressive suspension (leaf springs, bumpers)
- Dynamic suspension (truck's pneumatic suspension)
- Coefficient: 0.005
- Factor of 2 for twin wheels
- European truck cabin: drag 3, downforce 0
- American truck cabin: drag 2.3, downforce 0.002
- Position: point where the average drag is generated
Center Of Mass
- Refine CoM position with the suspension working. Use the weight per axle from specifications
ABS, ECS, ASR, TCS
Tandem + Trailer
Usually the combined mass is specified. Use 55% for tandem, 45% for trailer.