Free Motion

Joint allowing three translational and three rotational degrees of freedom

 Description 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: ${x}_{1}{y}_{1}$${z}_{1}$on body 1, and ${x}_{2}{y}_{2}$on body 2.  The free joint places no restrictions on the relative motion of the two frames, but simply provides a means for measuring the relative translations and rotations. The translation of the end frame, ${x}_{2}{y}_{2}$${z}_{2},$relative to the start frame, ${x}_{1}{y}_{1}$${z}_{1},$is represented by the vector, r , which is resolved into its three components in the ${x}_{1}{y}_{1}$${z}_{1}$ frame. The rotation of ${x}_{2}{y}_{2}$${z}_{2},$relative to ${x}_{1}{y}_{1}$${z}_{1}$, is represented by three Euler angles.

Connections

 Name Description ${\mathrm{frame}}_{a}$ Joint inboard frame ${\mathrm{frame}}_{b}$ Joint outboard frame

Parameters

 Symbol Default Units Description Modelica ID ${\mathrm{Type}}_{v}$ $\mathrm{Inboard}$ - Indicates whether the initial velocity is expressed in the inboard or outboard frame VelType ${\mathrm{Type}}_{\mathrm{θ}}$ - Indicates the sequence of body-fixed rotations used to describe the initial orientation of the joint.  For example, $\left[1,2,3\right]$ refers to sequential rotations about the x, then y, then z axis (123 - Euler angles) RotType ${\mathrm{Type}}_{\mathrm{ω}}$ $\mathrm{Euler}$ - 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 ${\mathrm{IC}}_{r,v}$ Ignore - Indicates whether MapleSim ignores, tries to enforce, or strictly enforces the translational initial conditions MechTranTree ${\stackrel{&conjugate0;}{r}}_{0}$ $\left[0,0,0\right]$ $m$ 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 ${\stackrel{&conjugate0;}{v}}_{0}$ $\left[0,0,0\right]$ $\frac{m}{s}$ 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 ${\mathrm{IC}}_{\mathrm{θ},\mathrm{ω}}$ Ignore - Indicates whether MapleSim ignores, tries to enforce, or strictly enforces the rotational initial conditions MechRotTree ${\stackrel{&conjugate0;}{\theta }}_{0}$ $\mathrm{rad}$ Initial rotation of the joint at the start of the simulation, based on the ${\mathrm{Type}}_{\mathrm{\theta }}$ parameter value InitAng ${\stackrel{&conjugate0;}{\omega }}_{0}$ $\frac{\mathrm{rad}}{s}$ Initial velocity of the joint at the start of the simulation, based on the ${\mathrm{Type}}_{\mathrm{ω}}$ parameter value InitAngVel