About Surface Constraints
Using surface constraints, you can fix the movement of a planar, cylindrical, or spherical surface in a particular direction, while allowing free movement in the other directions. The following surface constraints are available for 3D models:
• Planar Constraint—Enables full planar movement for planar surfaces, but restricts off-plane displacement.
• Pin Constraint—Controls the translation or rotation about the axis of only a cylindrical surface. It is particularly useful when a surface must move in one or more directions, but must be fixed in the remaining directions—for example, a piston that slides within a cylinder, but remains fixed to the inner cylinder wall and does not rotate.
• Ball Constraint—Represents a ball joint where the translation is fixed and the rotation is free.