What determines the position of the joint frame after using Simscape Multibody Link?

I have been tring to determine what is the orientation of joint frames in Simulinks Mechanic Explorer after I have exported the CAD model from SolidWorks to Simulink with Simscape Multibody Link. I'd like to know as I make a lot of exports and almost every time I have to position the parts differently just to get the frame be the right way around.

I found out by myself that some SolidWorks mates help determining, in what position the frame will be formed to. That's all though. I also looked through the .m file with different values the Rigid Transform blocks use, but I couldn't find a consistent logic from those.

Answer 1

[Ayush]

Hi Aatu,

I understand that you want to know the parameters responsible for the orientation of the joint frames when using Simscape Multibody Link.

Your finding of the orientation of joint frames in Simscape Multibody's Mechanic Explorer being determined by the mates in SolidWorks is indeed right. When exporting a CAD assembly from SolidWorks to Simscape Multibody, the Simscape Multibody Link plugin uses the mates to define the joint primitives (like revolute, prismatic, etc.) and their orientations. Please refer to the below documentation to know more about the “Simscape Multibody Link” and its integration with SolidWorks:

- https://www.mathworks.com/help/smlink/ref/linking-and-unlinking-simmechanics-link-software-with-solidworks.html

The following would provide a more comprehensive explanation of the working or mapping of the mates with the Simscape Multibody joint and its frames:

1. Concentric Mate: Creates a Revolute Joint in Simscape Multibody. The Joint frame is aligned with the axis of revolution in SolidWorks.
2. Coincident Mate: Creates a Weld Joint in Simscape Multibody. The Joint frame is aligned with the coincident face or edge in SolidWorks.
3. Distance Mate: Creates a Prismatic Joint in Simscape Multibody. The Joint frame is aligned with the direction of translation in SolidWorks.

To control the orientation of the joint frames as per your requirement, you should use the coordinate systems in SolidWorks strategically to help define the joint frame orientation. When you export the model, the Simscape Multibody Link plugin will use these coordinate systems to define the joint frames. To visualise the same in Mechanics Explorer, it can be done by enabling the "Show Frames" option.

Hope it helps,

Regards,

Ayush Misra