Spherical-Spherical (SimMechanics)

Represent a composite joint composed of two spherical primitives spatially separated by a massless connector of constant length

Library

Joints/Massless Connectors

Description

The Spherical-Spherical block represents a composite joint composed of two spherical joint primitives. The Body coordinate systems (CSs) on either side of the Joint are connected to the spherical primitives. The primitives are separated spatially by a vector of constant length but variable direction connecting the two Body CS origins. Both primitives are assembled.

The distance separation between the two axes is computed automatically from the Body CS origins to which the Joint is connected. This distance separation (the magnitude of the vector between the Body CS origins) remains fixed at its initial value during the simulation. This initial value must be nonzero.

You cannot connect a Massless Connector to an Actuator or a Sensor block.

You can 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 a reference CS to define the directions of the joint axes.

Massless Connector between Spherical and Spherical Joints

Dialog Box and Parameters

The dialog box has two active areas, Connection parameters and Parameters.

Connection Parameters

Current base: When you connect the base (B) Connector Port on the Spherical-Spherical block to a Body CS Port on a Body, this parameter is automatically reset to the name of this Body CS. See the following Spherical-Spherical base and follower Body Connector Ports figure.
Current follower: When you connect the follower (F) Connector Port on the Spherical-Spherical block to a Body CS Port on a Body, this parameter is automatically reset to the name of this Body CS. See the following Spherical-Spherical base and follower Body Connector Ports figure.

The base (B)-follower (F) Body sequence determines the sense of positive motion. Positive rotation is the base or follower pivoting as shown for the Spherical Joint.

Spherical-Spherical base and follower Body Connector Ports

Parameters

Toggle between the Axes and Advanced panels with the tabs.

The entries on the Axes pane are automatic. They specify the orientation of the spherical DoFs that the Spherical-Spherical represents.

Name: This column automatically displays the name of each primitive joint contained in the Joint block. For Spherical-Spherical, there are two spherical primitives, labeled S1 and S2, connecting to base and follower, respectively.
Primitive: This column automatically displays the type of each primitive joint contained in the Joint block. For Spherical-Spherical, there is only one primitive type, labeled Spherical.
Reference orientation [x y z]: These fields are not active.
Reference csys: These fields are not active.

The Advanced pane is optional. You use it to control the way SimMechanics interprets the topology of your schematic diagram.

Mark as the preferred cut joint: In a closed loop, one and only one joint is cut during the simulation. SimMechanics does the cutting internally and automatically.; If you want this particular joint to be weighted preferentially for cutting during the simulation, select the check box. The default is unselected.

See Also

Spherical

See Modeling Joints for more on representing DoFs with Massless Connectors.

See Checking Schematic Topology and How SimMechanics Works for more on closed loops and cutting.

Spherical Telescoping