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2021.1.1124.2 Wheel Joint



Overview

This kinematic relation is used to define a rotational constraint on an object.


Where to find

The Wheel Joint can be found under Mechanics > Kinematics > Kinematic Joints > Add Wheel Joint.

This will add the Wheel Joint component to the currently selected object or create a new empty GameObject with the component attached if no objects are selected.

Joints must be placed as children of a Kinematic Controller in the hierarchy.

The following inspector will be shown:


Feature layout

The image below shows the complete feature layout of the Wheel Joint component.

 

Generic Joint Settings

 

Pass Priority

Priority of the kinematic chain calculations. Higher numbers are calculated earlier.

Enforce Outside Playmode

Enforces the joint to work in edit mode.

Prevent Kinematic Update

Removes the joint from the kinematic chain calculations.

Prevent Further Updates on Object

Allows lower priority kinematic transforms on the same GameObject to be skipped in calculations.

Allow Direct User Input

Allows the user to manipulate the joint with the scene gizmo.

Min. User Input Translation Offset

The minimum value the user must input before translations are applied.

Min. User Input Rotation Offset

The minimum value the user must input before rotations are applied.

Kinematic Chaining

 

Create new Kinematic Relation

Creates a new relation between Transforms.

Opposing Relation Instance

The kinematic transform you want to link the joint to.

Relation Direction

Describes the direction of the manipulation of the Transforms. The following options are available:

  • BIDIRECTIONAL: Allows for both kinematic transforms, when they are being manipulated, to manipulate each other equally.

  • RECIEVE_ONLY: Allows for the joint, when it is being manipulated, to manipulate the opposing kinematic transform, but not the other way around.

  • SEND_ONLY: Allows for the opposing kinematic transform, when it is being manipulated, to manipulate the joint, but not the other way around.

Relation Type

Used when 2 different size Wheel Joints need the same rotational speed. The following options are available:

  • TRANSLATION: Translates the transforms using the Wheel Radius.

  • ROTATION: Translates the transforms without using the Wheel Radius.

Reverse Motion Direction

When enabled, the manipulation to/from the opposing kinematic transform is inverted.

Wheel Joint Settings

 

Wheel Radius

The Radius of the Wheel Joint.

Use Sceen Gizmo for Radius

When checked a handle in the Scene view is added and can be manipulated manually to set the Wheel Radius.

Notation

The angle notation for the Wheel Joint inspector. The following options are available:

  • DEGREES: displays the limits in degrees.

  • REVOLUTIONS: Displays the limits in number of revolutions.

  • RADIANS: Displays the limits in radians.

Limit Rotation

When checked, settings appear to set the minimum and maximum rotation of the Wheel Joint.

Minimum Rotation Limit

The minimum rotation limit of the Wheel Joint.

Use Scene Gizmo for Min. Rotation

When checked, a handle in the Scene view is added and can be manipulated manually to set the Minimum Rotation Limit.

Maximum Rotation Limit

The maximum rotation limit of the Wheel Joint.

Use Scene Gizmo to set Max. Limit.

When checked, a handle in the Scene view is added and can be manipulated manually to set the Maximum Rotation Limit.

Wheel Axis Direction

A Scene Vector describing the axis of the Wheel Joint.

Wheel Forward Direction

A Scene Vector describing the forward direction of the Wheel Joint.

Limit Rotation

 

Limit Rotation

When checked more settings appear to set the minimum and maximum rotation of the Wheel Joint.

Limit Notation

 

Minimum Rotation Limit

The minimum rotation limit of the Wheel Joint.

Use Scene Gizmo to set Min. Limit.

When checked a handle in the Scene view is added and can be manipulated manually to set the Minimum Rotation Limit.

Maximum Rotation Limit

The maximum rotation limit of the Wheel Joint.

Use Scene Gizmo to set Max. Limit.

When checked a handle in the Scene view is added and can be manipulated manually to set the Maximum Rotation Limit.

Current Rotation State

Current rotation of the wheel joint.

Sceneview Settings

 

Enable in Sceneview

When checked all gizmo’s and handles of the Wheel Joint are shown in the scene view if the GameObject is selected.

Always Enabled

When checked all gizmo’s and handles of the Wheel Joint are shown in the scene view even when the object is not selected.

Wheel Plane

The color of the Wheel Radius.

Axis Direction

The color for the Wheel Axis Direction.

Forward Direction

The color for the Wheel Forward Direction.

Current Rotation

The color for the Current Rotation State.

Rotation Limit

The color for the Minimum Rotation Limit and Maximum rotation limit.


How to use

  1. Add a Wheel joint to an object.

  2. Set the Wheel Axis Direction to the desired direction.

3. Set the Wheel Radius to the desired radius.

4. Create a new Transform Relation, add an Opposing Relation Instance and define the other settings as needed.

5. Test if the Transform Relations are working.

To test your Transform Relations outside of playmode make sure Enforce Outside Playmode is checked on both Joints.


How to use limits

  1. Click the Limit Rotation checkbox.

2. Use the Minimum Rotation Limit and Maximum rotation limit fields or use the scene gizmo’s to set the limits.

3. Test if the limits work by manipulating both Joints.

 

Prespective Documentation