Orientation in Motionview

Linn Liao

Hi,

I've been trying to setup a simple co-simulation with Motionview and Twin activate. The motionview model is a crane and the altair has a simple PID controller to control the tower angle. I am not familiar with markers and how they work, so so far I've been only using the global marker. I setup the co-simulation and ran the analysis on Twin activate, but I see that all plant output signals of my model starts from 0, although their geographical position in the global frame is obivously away from the origin. What can I do to fix this, do I need to add markers?

(I tried to make a new markersat the pivot point of the tower and later substitutted the previously used global marker with the new one and it seems move the body away from where it used to be. Why?)

Thanks in advance!

Linn

GTT Adam

Hi Linn,

Markers are an entity that defines orientation at a point. They are commonly used in expressions in order to determine the relative distance, velocity, or acceleration from one marker to another. To measure the distance from one marker to another, you would define an expression using either DX, DY, DZ, or DM like the following:

`DX({marker_1.idstring},{marker_2.idstring},{marker_1.idstring})`

Where this would compute the distance along the X axis from marker 1 to marker 2 relative to the orientation of marker 1.

Marker Documentation:

• https://help.altair.com/hwdesktop/hwx/topics/motionview/markers_r.htm?zoom_highlight=markers

MotionSolve Functions Documentation:

• https://help.altair.com/hwsolvers/ms/topics/chapter_heads/functions.htm

 

Based on your description, yes you will need to add markers at locations of interest.

 

Markers are a fundamental entity of MBD, and such I would recommend completing our MotionView/MotionSolve Introduction v2023 eLearning to better understand these basic concepts:

MotionView/MotionSolve Introduction v2023 eLearning:

• https://learn.altair.com/enrol/index.php?id=496

 

Hope this helps!

Adam Reid