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Disassembled Spherical

Primitive joint with misaligned base and follower axes containing three rotational degrees of freedom

Library

Joints/Disassembled Joints

Description

The Disassembled Spherical block represents three rotational degrees of freedom (DoF) about a pair of specified dislocated pivots at the two bodies, separated "ball-in-socket" joints. SimMechanics™ simulation automatically assembles (collocates) the spherical pivots at simulation start when it defines a machine's assembled configuration.

Two rotational DoFs specify a directional axis, and a third rotational DoF specifies rotation about that directional axis. (See the motion figure in the Spherical block reference page.) The sense of each rotational DoF is defined by the right-hand rule. Unlike the Gimbal block, the Disassembled Spherical block cannot become singular.

Disassembled Spherical Pivots of Follower (blue) and Base (red)

Satisfying Joint Requirements

A Joint block represents the relative degrees of freedom between two bodies, not the bodies themselves.

You must connect any Joint block to two and only two Body blocks, the base and the follower. All Joints have a default of two connector ports for these connections, defining the direction of joint motion (base to follower). You connect each side of the Joint block to these Body blocks at a Body coordinate system (CS) point.

You specify the joint primitive axes, if any, in the Joint dialog. The two disassembled primitive joint axes are associated, in order, with the base and follower Bodies, respectively.

You cannot connect an Actuator or Sensor to a Disassembled Joint.

Assembly Restrictions on Disassembled Joints

This Joint block is disassembled: the connected Body CS origins do not need to be spatially collocated points or lie within the span of prismatic primitives, if any.

You can only use a Disassembled Joint block within a closed loop. One loop can have no more than one disassembled joint.

Dialog Box and Parameters

The dialog has one area, Connection parameters, which is inactive.

Connection Parameters

Current base

When you connect the base (B) connector port on the Disassembled 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 figure, Disassembled Spherical Base and Follower Body Connector Ports.

Current follower

When you connect the base (F) connector port on the Disassembled 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 figure, Disassembled Spherical Base and Follower Body Connector Ports.

Disassembled Spherical Base and Follower Body Connector Ports

See Also

Disassembled Cylindrical, Disassembled Prismatic, Disassembled Revolute, Gimbal, Spherical

See Modeling Degrees of Freedom for more on representing DoFs with Disassembled Joints.

See Checking Model Topology and How SimMechanics Software Works for more on closing loops with disassembled joints.

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