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 earth initializes the position, velocity, and acceleration of Side 1 for connection with a set of multibody components. The transformation matrix is initialized with Z pointing down X pointing north and Y pointing east. LinAccel1[2] is set to -9.81 so that the effects of gravity are taken into account in the multibody simulation. The LinkNumber[0] is set to zero since the earth component does not need to know what internal forces are acting on it. The position is set to the initial position. The orientation and the velocities are set to zero.

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

Outputs:

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

SimRealVar InitPos[3] - Initial Position (m)
 

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