RBD Car Rig 1.0 geometry node

Builds a drivable RBD Car Rig.

Since

20.0

This SOP takes oriented car geometry and builds the proxy geometry for the body, wheels, and optionally the steering wheel, and creates the appropriate constraints to be able to drive the car with full suspensions and motors.

For more information, see Using the RBD car rig.

Parameters ¶

Wheels Group

Specify the wheels geometry group. These will be automatically split along to the geometry center into Front, Back, Left, and Right wheels.

Steering Wheel Group

Specify an optional steering wheel geometry group. This will automatically rotate the steering wheel geometry according to the steering inputs, without contributing to the RBD simulation.

Ignore Group

Geometry to ignore when generating the car body’s proxy collision geometry. Typically this would include antennas which might protrude and alter the overall volume of the car body in a significant way.

Show Geometry

Turn this off to hide the car geometry and guides - this is handy when having the viewer state active while running the simulation in order to drive the car through a RBD Bullet Solver and not have the static car visible.

Show Body Proxy Geometry

Turn this on to show the resulting proxy geometry for the car body as a wireframe guide.

HUD Scale

Guide geometry’s widget scale.

Drive Mode

Front Wheel Drive

Only adds motors to the front wheels.

Rear Wheel Drive

Only adds motors to the rear wheels.

4×4

All wheels have motors applied.

Drive ¶

Steer

Steer the car from left (-1) to right (+1) with 0 being the front wheels aligned to center.

Speed

Specify the target speed in KPH or MPH for the motors. They will automatically adjust to the size of the wheels.

Brake

Apply front wheel brakes.

Hand Brake

Apply rear wheel brakes.

Interactive ¶

Steering Increments

The increments applied to the steering when using the viewport python state’s Turn Left and Turn Right hotkeys.

Speed Increments

The increments applied to the speed when using the viewport python state’s Accelerate and Decelerate hotkeys.

Configure ¶

Wheel Layout

Choose from a variety of predefined wheel layouts or an entirely custom one.

4 Wheels

The typical 4 wheel car layout.

3 Wheels - 1 Front 2 Back

Tricycle/Delta wheel layout.

3 Wheels - 2 Front 1 Back

Tadpole/Reverse Trike layout.

3 Axles

The layout for trucks with 2 front wheels on 1 axle and 4 or more wheels on 2 axles.

Custom

Customize the wheel layout by specifying each wheel independently and specify its role. Each wheel can steer (rotate when turning), the direction of which is determined by its position setting. Front wheels will steer in the direction of the turn while Back wheels will steer in the opposite direction.

Specifying a side (Left or Right) will affect the wheels speed when a Differential is active, and determine the direction the wheel will lean in when specifying a Camber. When the side is set to Center, the wheel will be unaffected by either of these settings.

Configure Mode

Simple

Use the same settings for all wheels.

Front/Back

Use different settings for the Front wheels and Back wheels.

Individual

Configure each wheel separately.

Center of Mass (Length and Height)

Position the car body’s center of mass along its length and height. Higher COMs will allow the car to roll over in turns while lower COMs will help prevent that from happening.

Min/Max Speed

The speed limits applied to the car when driving interactively.

Acceleration Profile

When driving interactively, pressing the W (accelerate) or S keys (decelerate) will react faster or slower depending on the car’s current speed in relation its min and max speeds and the profile of this curve.

Ackermann Steering Angle

Controls the percentage of the Ackermann steering angle applied to the steering wheels of the vehicle. Ackermann steering geometry is designed to ensure that the inner and outer wheels turn at appropriate angles during a turn, minimizing tire slip and improving maneuverability.

Camber

Controls the tilt of the vehicle’s wheels relative to the vertical axis when viewed from the front or rear of the car. Adjusting the camber angle affects the tire’s contact patch with the ground, which influences handling and overall vehicle stability. A negative camber will tilt the top of the wheels inwards, while a positive camber will tilt them outwards.

Caster Angle

Controls the angle of the steering axis relative to the vertical axis of the vehicle when viewed from the side. Adjusting the caster angle affects the steering stability, self-aligning torque, and overall handling characteristics of the vehicle.

Tire Friction

The friction coefficient applied to the wheels. This controls the grip of the tires to the ground, which helps move the car forward.

Tire Bounce

The elasticity of the wheels.

Wheel Wobble

When greater than 0, allows the wheel to spin in all directions, allowing it to wobble like a broken shopping cart wheel.

Wheel Scale

Scale of the automatically created wheel proxy geometry. Since this is generated automatically to fit the wheel geometry, it might be necessary to scale this down a little. When doing post-sim tire deformations, scaling it down will allow the tire to penetrate the ground a little.

Suspension ¶

Stiffness

The stiffness of the suspensions.

Damping

Specify how much damping is applied when matching the wheels' initial vertical position.

Travel

Specify the maximum distance the wheels can travel both up and down as a ratio of their diameter.

Motors ¶

Differential

None

The motors on all the wheels rotate at the same speed.

Locked

Both wheels on the same axle rotate at the same speed. The front wheels will spin faster when the steering is engaged.

Limited-Slip

Reduces the loss of drive which can result from spinning wheels on one side of an axle. The wheels on the inside of the turn direction will spin more slowly than the wheels on the outside, with the front wheels spinning faster than the rear wheels.

Max Impulse

The maximum impulse the solver is allowed to apply to the motors to reach the target speed.

Constraints ¶

Constraint Iterations

Specify the number of constraint iterations for the constraint solver. In order for the constraints to behave properly, a high constraint iteration may be required.