[MBDyn-users] module-collision is complete, tested, and ready for use.

doug at baldwintechnology.com doug at baldwintechnology.com
Fri Jan 8 06:21:49 CET 2016

With major improvements, module-collision is now absolutely precise and
robust. The Bullet collision library was replaced by the Flexible
Collision Library (FCL), with a hat tip to Jens van Schelve for the
suggestion. This combination of FCL and the MBDyn collision-module is now
useful for productive work involving plane-sphere and sphere-sphere
collisions, and serves as an extensible platform for collisions of any
number of objects of any shape. (All issues noted in an earlier YouTube
video were resolved, and that video was replaced by an updated YouTube
video, https://youtu.be/nigfe1SM4E4 )

Areas for future research include mapping Constitutives to material pairs,
and vetting/modifying FCL for a menu of shape pairs having MBDyn levels of

I believe it truly can be said that MBDyn now features accurate collision
simulation, and a fully integrated GUI for pre- and post- processing. For
further information, please see the 15 minute video at this link,
https://youtu.be/nigfe1SM4E4 . The code itself is available here,
https://github.com/gdbaldw .

-Doug Baldwin

> I've corrected the static friction calculations in AssRes, so the
> acceleration and related plotting issue mentioned in the video no longer
> exists. The code seems very complete now, and is committed to github.
> We still need a more accurate collision detection library. If you are
> aware of a suitable alternative to the Bullet Physics collision library,
> please let me know. For now, spheres and infinite static plans may be
> safely modeled, because these Bullet shapes have the accuracy that MBDyn
> demands. The other Bullet shapes will work, but accuracy must be carefully
> considered.
> Thanks,
> -Doug Baldwin
>> module-collision is complete, tested, and ready for use. Static and
>> dynamic friction, depth of penetration, as well as viscoelastive normal
>> forces are simulated. The module is fully integrated with
>> BlenderAndMBDyn,
>> with a video demonstration available at https://youtu.be/NbUDrYvAbW4.
>> The
>> module has robust convergence, and is ready for use in practical
>> engineering applications, I believe. It appears to be limited only by
>> the
>> inherent limitations of the Bullet collision library, which has MBDyn
>> levels of accuracy and precision for sphere shapes and static infinite
>> planes only. The MBDyn model used in the demonstration video is attached
>> to this e-mail, and the associated BlenderAndMBDyn model is available at
>> https://groups.google.com/d/msg/mbdyngsoc2015/2tBFoqiGatQ/FOdTNCDWCwAJ.
>> The module itself is available at
>> https://github.com/gdbaldw/module-collision, and requires a minor patch
>> to
>> rodj.cc, which is also posted at the github site.
>> -Doug Baldwin_______________________________________________
>> MBDyn-users mailing list
>> MBDyn-users at mbdyn.org
>> https://mail.mbdyn.org/cgi-bin/mailman/listinfo/mbdyn-users

More information about the MBDyn-users mailing list