In SolidWorks^{®}, unmated parts have six mechanical degrees of freedom (DoFs) that describe how the parts can move with respect to each other. Of the six degrees of freedom, three are rotational and three are translational. Applying a mate between two parts eliminates degrees of freedom between the two parts. Mates can remove between zero and six degrees of freedom.
SimMechanics™ assigns six degrees of freedom to an unconstrained rigid body. The unconstrained rigid body behaves as a free body — it can rotate and translate, about or along three mutually orthogonal axes. The following table lists the degrees of freedom of a rigid body in different configurations.
Rigid Body Condition | Degrees of Freedom |
---|---|
Not connected to joints, constraints, or World Frame | 0 |
Connected to Joints or Constraints blocks | Add degrees of freedom as specified by joint or constraint |
During CAD export, SimMechanics Link maps SolidWorks mates between parts to SimMechanics joints between rigid bodies. CAD mates and SimMechanics joints do not follow a one-to-one correspondence — multiple mates 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.
Primitive | Abbreviation | Motion Type | Number of DoFs |
---|---|---|---|
Prismatic | P | Translational | 1 |
Revolute | R | Rotational | 1 |
Spherical | S | Rotational | 3 |
Depending on the constraint combination, SimMechanics Link utility supports the following Inventor^{®} constraint entities:
Entity | Description |
---|---|
Circle/Arc | Circular edge/arc sketch segment* |
Ellipse/Arc | Elliptical edge/arc sketch segment* |
Cone | Conical 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.
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. |
The following table identifies supported constraint-entity combinations for the Coincident constraint. A ✓ indicates the combination is supported.
Mate-Entity 2 | |||||||
Point | Line | Plane | Cylinder | Cone | Circle/Arc | ||
Mate-Entity 1 | Point | ✓ | |||||
Line | ✓ | ✓ | |||||
Plane | ✓ | ✓ | ✓ | ||||
Cylinder | ✓ | ✓ | ✓ | ||||
Cone | ✓ | ✓ | ✓ | ||||
Circle/Arc | ✓ | ✓ | ✓ | ✓ |
The following table identifies supported constraint-entity combinations for the Concentric mate. A ✓ indicates the combination is supported.
Mate-Entity 2 | |||||||
Point | Line | Plane | Cylinder | Cone | Circle/Arc | ||
Mate-Entity 1 | Point | ||||||
Line | ✓ | ✓ | ✓ | ||||
Plane | ✓ | ||||||
Cylinder | ✓ | ✓ | ✓ | ✓ | |||
Cone | ✓ | ✓ | ✓ | ✓ | |||
Circle/Arc | ✓ | ✓ | ✓ | ✓ |
The following table identifies supported constraint-entity combinations for the Perpendicular mate. A ✓ indicates the combination is supported.
Mate-Entity 2 | |||||||
Point | Line | Plane | Cylinder | Cone | Circle/Arc | ||
Mate-Entity 1 | Point | ||||||
Line | ✓ | ✓ | |||||
Plane | ✓ | ✓ | |||||
Cylinder | |||||||
Cone | |||||||
Circle/Arc |
The following table identifies supported constraint-entity combinations for the Parallel mate. A ✓ indicates the combination is supported.
Mate-Entity 2 | |||||||
Point | Line | Plane | Cylinder | Cone | Circle/Arc | ||
Mate-Entity 1 | Point | ||||||
Line | ✓ | ✓ | |||||
Plane | ✓ | ✓ | |||||
Cylinder | ✓ | ||||||
Cone | ✓ | ||||||
Circle/Arc |
The following table identifies supported constraint-entity combinations for the Distance mate. A ✓ indicates the combination is supported.
Mate-Entity 2 | |||||||
Point | Line | Plane | Cylinder | Cone | Circle/Arc | ||
Mate-Entity 1 | Point | ✓ | ✓ | ||||
Line | ✓ | ||||||
Plane | ✓ | ✓ | ✓ | ||||
Cylinder | |||||||
Cone | |||||||
Circle/Arc |
The following table identifies supported constraint-entity combinations for the Angle mate. A ✓ indicates the combination is supported.
Mate-Entity 2 | |||||||
Point | Line | Plane | Cylinder | Cone | Circle/Arc | ||
Mate–Entity 1 | Point | ||||||
Line | ✓ | ||||||
Plane | ✓ | ||||||
Cylinder | |||||||
Cone | |||||||
Circle/Arc |
The SimMechanics Link utility supports the following SimMechanics joint-primitive combinations.
Primitive Combination | SimMechanics Block |
---|---|
P | Prismatic |
PP | In-Plane |
PPP | Custom Joint |
PPPR | Custom Joint |
S | Spherical |
R-S | Revolute-Spherical |
R | Revolute |
PR | Cylindrical |
PPR | Planar |
PPPS | Six-DoF |
R-R | Revolute-Revolute |
S-S | Spherical-Spherical |
W | Weld |
The point-point coincident mate maps onto a spherical joint.
The point-point distance mate maps onto a spherical-spherical massless connector.
The following limitation applies to CAD export from SolidWorks.
If the SimMechanics Link utility fails to translate a CAD constraint, a Weld joint replaces the constraint.
For SimMechanics Link to successfully map the CAD point-point distance mate onto a SimMechanics spherical-spherical massless connector, the mate must not connect to any other mates.