Free Motion
Joint allowing three translational and three rotational degrees of freedom
Description
Connections
Parameters
See Also
A free joint, sometimes called a 6-DOF joint or motion sensor, is shown in the diagram below with two reference frames at either end of the connection: x1y1z1⁢on body 1, and x2y2z2⁢ on body 2. The free joint places no restrictions on the relative motion of the two frames, but simply provides a means for measuring the relative translations and rotations. The translation of the end frame, x2y2z2,relative to the start frame, x1y1z1,is represented by the vector, r , which is resolved into its three components in the x1y1z1 frame. The rotation of x2y2z2,relative to x1y1z1, is represented by three Euler angles.
Name
framea
Joint inboard frame
frameb
Joint outboard frame
Symbol
Default
Units
Modelica ID
Typev
Inboard
Indicates whether the initial velocity is expressed in the inboard or outboard frame
VelType
Typeθ
1,2, 3
Indicates the sequence of body-fixed rotations used to describe the initial orientation of the joint. For example, 1,2,3 refers to sequential rotations about the x, then y, then z axis (123 - Euler angles)
RotType
Typeω
Euler
Indicates whether the initial angular velocity is expressed in the inboard or outboard frame. If Euler is selected, the initial angular velocities are assumed to be the direct derivatives of the Euler angles.
AngVelType
ICr,v
Ignore
Indicates whether MapleSim ignores, tries to enforce, or strictly enforces the translational initial conditions
MechTranTree
r&conjugate0;0
0,0,0
m
Initial displacement of the joint at the start of the simulation, expressed along the x-, y-, and z-axis of the inboard frame respectively
InitPos
v&conjugate0;0
ms
Initial velocity of the joint at the start of the simulation, expressed along the x-, y-, and z-axis of the inboard frame respectively
InitVel
ICθ,ω
Indicates whether MapleSim ignores, tries to enforce, or strictly enforces the rotational initial conditions
MechRotTree
θ&conjugate0;0
0,0, 0
rad
Initial rotation of the joint at the start of the simulation, based on the Typeθ parameter value
InitAng
ω&conjugate0;0
rads
Initial angular velocity of the joint at the start of the simulation, based on the Typeω parameter value
InitAngVel
Joints and Motions
Multibody Overview
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