A wheel rolling on the x-y plane of the world frame including
wheel mass and simple visualization.
The rolling contact is considered being ideal, i.e. there is no
slip between the wheel and the ground.
The wheel can not take off but it can incline toward the ground.
The frame frame_a is placed in the wheel center point and rotates
with the wheel itself. Therefore, a
rotational joint
with rotation axis n={0,1,0}
should be used to
connect the wheel to a carrier.
To work properly, the gravity acceleration vector g of the world must point in the negative z-axis, i.e.
inner Modelica.Mechanics.MultiBody.World world(n={0,0,-1});