Wheel joints



See here for a video explaining this topic: YouTube

To edit joints you must first be in joint edit mode (shortcut key 'J').

Wheel joint creation position
A wheel joint will be created with the joint anchor position for both bodies placed at the cursor position. Body A will become the chassis body, and body B will become the rotating 'wheel' body. The axis of the joint will be fixed to body A.

In the image below, suppose we have the typical case of a wheel being attached to a vehicle. The easiest way to arrange this is to place the wheel body in the location it should be attached, and place the cursor in the center of the wheel.

The joint axis is (0,1) by default when the joint is created.


Moving joint anchors
Wheel joint anchor positions can be translated and rotated in a similar way to other items. The main difference is that one joint has two joint anchors. Initially the manipulation will start with the joint anchor for bodyA, and you can switch between joint anchors while manipulating them by hitting the same key that started the manipulation.

For example to begin translating joint anchors you would hit 'T', and this would begin translation of the joint anchor for body A. Hitting 'T' again would switch to translation of the joint anchor for body B.

When the position of the anchor in body B is not on the axis line, a red dashed line will be displayed to show how far away it is from the axis.


Rotating the joint axis
Hitting 'R' a third time while rotating the joint anchors will allow you to rotate the axis of the joint. Use the mouse to rotate the axis and click the left mouse button to confirm the new angle, or hit Escape to cancel the change.


Wheel joint motors
Joint motor values can be set in the properties panel. For most applications, the settings for joint motors will be controlled at runtime after loading the scene, but for motor settings that will not change throughout the lifetime of the scene, or just to experiment and see how different values behave, it can be handy to try them in R.U.B.E first.