Description:

The coordinate system is right hand rule. X cross Y gives Z and Roll is right hand rule about X, Pitch is right hand rule about Y, and Yaw is right hand rule about Z.

Vector Storage:

All linear three vectors (LinPos, LinVel) store their values as [X, Y, Z].
All angular three vectors (AngVel) store their values as [Roll, Pitch, Yaw].
The transformation matrix TM is stored:

Pre-multiplying a local vector by the TM will generate the vector in global coordinates.

Multibody Dynamics, Link Numbers and 60 and 20 Length Vectors:

Please refer to Multibody Dynamics and 60 Length Vectors for information on 60
length vectors.

Methodology:

The spherical joint models both a spherical mechanism and a body with Mass and angular Inertia. The mass is located CGOffset away from the spherical joint. CGOffset is in the local coordinates of the downstream body. LocalJointAxis defines the axis about which the body rotates. The LocalJointAxis is defined in the local coordinates of the upstream body's coordinate system.

The spherical joint is modeled using a combination of a Spherical component and a MassMB
component. The multibody solver calculates the actual joint accelerations, which are integrated and output in JointAngRate and JointAng.
 

SimRealVar Force1[60] - Global Force (N)
SimRealVar Moment1[60] - Global Moment (Nm)

Outputs:

SimRealVar LinAccel1[60] - Global Linear Acceleration (m/s/s)
SimRealVar LinVel1[3] - Global Linear Velocity (m/s)
SimRealVar LinPos1[3] - Global Linear Position (m)
SimRealVar AngAccel1[60] - Global Angular Acceleration (rad/s/s)
SimRealVar AngVel1[3] - Global Angular Velocity (rad/s)
SimRealVar TM1[9] - Transformation Matrix (ND)
SimRealVar LinkNumber1[20] - Link Number Output (ND)
 

SimRealVar Inertia[3] - Inertia of Body (kg-m-m)
SimRealVar Mass - Mass of Body (kg)
SimRealVar CGOffset[3] - CG Offset in Body Coordinates (m)
SimRealVar LocalJointAxis[3] - Local Joint Axis (ND)
 

SimRealVar LinAccel3[60] - Global Linear Acceleration (m/s/s)
SimRealVar LinVel3[3] - Global Linear Velocity (m/s)
SimRealVar LinPos3[3] - Global Linear Position (m)
SimRealVar AngAccel3[60] - Global Angular Acceleration (rad/s/s)
SimRealVar AngVel3[3] - Global Angular Velocity (rad/s)
SimRealVar TM3[9] - Transformation Matrix (ND)
SimRealVar LinkNumber3[20] - Link Number Output (ND)

Outputs:

SimRealVar Force3[60] - Global Force (N)
SimRealVar Moment3[60] - Global Moment (Nm)
 

SimRealVar JointAng[3] - Joint Angle (rad)
SimRealVar JointAngRate[3] - Joint Angular Rate (rad/s)
 

return to component list