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# Documentation

## Constraint-Joint Mapping

### CAD Constraint – SimMechanics Joint Mapping

During CAD export, SimMechanics™ Link maps Creo™ constraints between parts to SimMechanics joints between rigid bodies. CAD constraints and SimMechanics joints do not follow a one-to-one correspondence — multiple constraints can map into a single joint. All SimMechanics joints contain a combination of three joint primitives: Prismatic, Revolute, and Spherical. The Weld Joint block contains zero joint primitives, and therefore zero degrees of freedom. The following table identifies the degrees of freedom of each joint primitive.

PrimitiveAbbreviationMotion TypeNumber of DoFs
PrismaticPTranslational1
RevoluteRRotational1
SphericalSRotational3

### Supported Constraint Entity

Depending on the constraint combination, SimMechanics Link utility supports the following Creo constraint entities:

Entity Description
Circle/ArcCircular edge/arc sketch segment*
Ellipse/ArcElliptical edge/arc sketch segment*
ConeConical face
Cylinder Cylindrical face
Line Linear edge/sketch segment/reference axis
Plane Reference plane or planar face
Point Vertex/sketch point/reference point

* A complete circle or ellipse is a special case of a circular or elliptical arc.

### Supported Constraint Entity Combinations

The following sections list the constraint-entity combinations that SimMechanics Link supports for different constraint types.

 Note:   If the SimMechanics Link exporter cannot translate a constraint–constraint entity combination into a supported SimMechanics joint with DoFs, it converts the combination into a weld (W) primitive.

#### Coincident Constraint

The following table identifies supported constraint-entity combinations for constraints:

• Align without offset

• Mate without offset

• Point on Line

• Edge on Surface

• Point on Surface

A ✓ indicates the combination is supported.

 Constraint-Entity 2 Point Line Plane Cylinder Cone Circle/Arc Constraint-Entity 1 Point ✓ Line ✓ ✓ Plane ✓ ✓ ✓ Cylinder ✓ ✓ ✓ Cone ✓ ✓ ✓ Circle/Arc ✓ ✓ ✓ ✓

#### Insert Constraint

The following table identifies supported constraint-entity combinations for the Insert constraint. A ✓ indicates the combination is supported.

 Constraint Entity 2 Point Line Plane Cylinder Cone Circle/Arc Constraint Entity 1 Point Line ✓ ✓ Plane ✓ Cylinder ✓ ✓ ✓ ✓ Cone ✓ ✓ ✓ ✓ Circle/Arc ✓ ✓ ✓ ✓

#### Align or Mate Constraint with Translational Offset

The following table identifies supported constraint-entity combinations for the Align or Mate constraints with translational offset. A ✓ indicates the combination is supported.

 Constraint Entity 2 Point Line Plane Cylinder Cone Circle/Arc Constraint Entity 1 Point ✓ ✓ Line ✓ Plane ✓ ✓ ✓ Cylinder Cone Circle/Arc

#### Align or Mate with Rotational Offset

The following table identifies supported constraint-entity combinations for the Align or Mate constraints with rotational offset. A ✓ indicates the combination is supported.

 Constraint Entity 2 Point Line Plane Cylinder Cone Circle/Arc Constraint Entity 1 Point Line ✓ Plane ✓ Cylinder Cone Circle/Arc

### Supported SimMechanics Joints

The SimMechanics Link utility supports the following SimMechanics joint-primitive combinations.

Primitive CombinationSimMechanics Block
PPrismatic Joint
PPRectangular Joint
PPPCartesian joint
SSpherical joint
RRevolute Joint
PRCylindrical Joint
PPRPlanar Joint
PPPS6-DOF Joint
WWeld joint