Documentation

Assembly

Connect bodies through joints, gears, and constraints

Connect bodies with joint and constraint blocks to assemble them into an articulated system. The joint blocks determine the maximum degrees of freedom—rotational and translational—allowed between the connected bodies. The constraint blocks reduce this number by applying kinematic relationships that often couple degrees of freedom. There are no restrictions on model topology: you can model kinematic trees such as a double pendulum and kinematic loops such as a four bar.

Simscape Blocks

Joints with One or No Primitives

Prismatic JointJoint with one prismatic primitive
Revolute JointJoint with one revolute primitive
Spherical JointJoint with one spherical primitive
Weld JointJoint with zero primitives

Joints with Multiple Primitives

6-DOF JointJoint with one spherical and three prismatic primitives
Bearing JointJoint with one prismatic and three revolute primitives
Bushing JointJoint with three prismatic and three revolute primitives
Cartesian JointJoint with three prismatic primitives
Cylindrical JointJoint with one prismatic and one revolute primitives possessing parallel motion axes
Gimbal JointJoint with three revolute primitives
Pin Slot JointJoint with one prismatic and one revolute primitives possessing mutually orthogonal motion axes
Planar JointJoint with one revolute and two prismatic primitives
Rectangular JointJoint with two prismatic primitives
Telescoping JointJoint with one prismatic and one spherical joint primitive
Universal JointJoint with two revolute primitives

Joints with Coupled Degrees of Freedom

Constant Velocity JointJoint with two rotational DoFs between shafts constrained to spin with equal velocity
Lead Screw JointJoint with coupled rotational and translational degrees of freedom
Bevel Gear ConstraintKinematic constraint between two bevel gear bodies with angled intersecting rotation axes
Common Gear ConstraintKinematic constraint between two coplanar spur gear bodies with parallel rotation axes
Rack and Pinion ConstraintKinematic constraint between a translating rack body and a rotating pinion body
Worm and Gear ConstraintKinematic constraint between worm and gear bodies with perpendicular non-intersecting rotation axes
Angle ConstraintFixed angle between two frame Z axes
Distance ConstraintFixed distance between two frame origins
Point On Curve ConstraintKinematic constraint between a frame origin and a curved path
Rigid TransformFixed spatial relationship between frames
World FrameInertial reference frame

Topics

Assembling Bodies with Joints

Multibody Assembly Workflow

Workflow steps for assembling body subsystems into an articulated multibody model.

How Multibody Assembly Works

Connecting bodies with joints, positioning and orienting joint frames through rigid transforms, and guiding joint assembly through by specifying joint state targets.

Modeling Joint Connections

Role of joints in a multibody model. Joints as systems of joint primitives with elementary degrees of freedom. Accounting for the effects of joint inertia in a model.

Model an Open-Loop Kinematic Chain

Assemble body subsystems and revolute joints into an open-loop kinematic chain.

Model a Closed-Loop Kinematic Chain

Assemble body subsystems and revolute joints into a closed-loop kinematic chain.

Troubleshoot an Assembly Error

Use Mechanics Explorer and Model Report to identify and correct a model assembly error.

Constraining Multibody Assemblies

Modeling Gear Constraints

Learn how to model gear constraints using simple gear models as examples.

Counting Degrees of Freedom

Using the Simscape™ Statistics Viewer to determine the motion degrees of freedom in a mechanism.

Assemble a Gear Model

Learn how to satisfy the assembly requirements of gear constraints using Rigid Transform blocks.

Model a Compound Gear Train

Use the Common Gear Constraint block to couple the rotational motions of the bodies comprising a planetary gear system.

Constrain a Point to a Curve

Use a Point on Curve Constraint block to restrict the motion of an aircraft flap to a curved trajectory specified in a Spline block.

Featured Examples

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