| SimMechanics™ | |
Joints
The In-Plane block represents a composite joint with two translational degrees of freedom (DoFs) as two prismatic primitives. There are no constraints among the primitives.
Warning A joint with two prismatic primitives becomes singular if the two translation axes become parallel. The simulation stops with an error in this case. |
You must connect each side of the Joint block to a Body block at a Body coordinate system (CS) point. The In-Plane block is assembled: the origins of these Body CSs must lie along the primitive axes, within assembly tolerancesBut the Body CS origins on either side of the Joint do not have to be spatially collocated points.
You must connect any Joint block to two and only two Body blocks, and Joints have a default of two connector ports for connecting to base and follower Bodies.
A Joint block represents only the abstract relative motion of two bodies, not the bodies themselves. You must specify reference CSs to define the directions of the joint axes.
The dialog has two active areas, Connection parameters and Parameters.
The base (B)-follower (F) Body sequence determines the sense of positive motion. Positive translation is the follower moving in the direction of the translation axis.
When you connect the base (B) connector port on the In-Plane block to a Body CS Port on a Body, this parameter is automatically reset to the name of this Body CS. See the following figure, In-Plane Base and Follower Body Connector Ports.
The base Body is automatically connected to the first joint primitive P1 in the primitive list in Parameters.
When you connect the follower (F) connector port on the In-Plane block to a Body CS Port on a Body, this parameter is automatically reset to the name of this Body CS. See the following figure, In-Plane Base and Follower Body Connector Ports.
The follower Body is automatically connected to the last joint primitive P2 in the primitive list in Parameters.
Using this spinner menu, you can set the number of extra connector ports needed for connecting Joint Actuator and Joint Sensor blocks to this Joint. The default is 0.
The motion of prismatic primitives is specified in linear units.
In-Plane Base and Follower Body Connector Ports
Toggle between the Axes and Advanced panels with the tabs.
The entries on the Axes pane are required. Each DoF primitive in In-Plane has an entry line. These lines specify the direction of the axes of action of the DoFs that the In-Plane represents.
The primitive list states the names and types of joint primitives that make up the In-Plane block: prismatic primitives P1, P2.
Enter here as a three-component vector the directional axes defining the allowed motions of these primitives and their corresponding DoFs:
Prismatic: axis of translation
The default vectors are shown in the dialog above. The axis is a directed vector whose overall sign matters.
To prevent singularities and simulation errors, the two prismatic axes cannot be parallel.
Using the pull-down menu, choose the coordinate system (World, the base Body CS, or the follower Body CS) whose coordinate axes the vector axis of action is oriented with respect to. This CS also determines the absolute meaning of forces/torques and motion along/about the joint axis. The default is World.
The Advanced pane is optional. You use it to control the way SimMechanics™ simulation interprets the topology of your schematic diagram.
In a closed loop, the simulation internally and automatically cuts one and only one joint.
If you want this particular joint to be weighted preferentially for cutting during the simulation, select the check box. The default is not selected.
See Modeling Degrees of Freedom for more on representing DoFs with Joints.
See Verifying Machine Topology and How SimMechanics™ Software Works for more on closed loops and cutting.
| Ground | Joint Actuator | |
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