On 5/23/2011 9:17 AM, Javier Ros wrote: > Viesturs, > > Just in case, and without trying to dig deep into the problem: > > Euler angles can be singular at certain positions. That is they are unable > to > give a rotation or base change matrix when at such positions. > > If you experience estrange problems only when the angles are close to 0 or > to 90 degrees it is possible that our problem is related to this. > > <...> > > Hope this helps, > > Javier > Viesturs et al.:
Javier is quite correct. If you want go to searching for explanations, The situation is called "gimbal lock" and the USA could have lost the Lunar Lander on the Apollo 11 mission because of it (http://en.wikipedia.org/wiki/Gimbal_lock). It's bad enough when your wrist flips over. It's got to be a lot scarier when your spacecraft controls lock up! I meant to bring it up yesterday when I saw your description but instead I went to watch my grandson play soccer/football. Sorry, but grandkids come first:-) As an aside, I have no experience---practical or theoretical---with robot arms but I'm interested in your problem because I want my grandson and I to build a robot arm as part of a chess-playing machine. It will be more along the lines of a LynxMotion arm in size and robustness, but I still have to understand the kinematics. I used your list of serial-kinematics requirements (email message 2011/1/4) as an exercise to learn how to use Creo Elements Personal Edition from PTC. If I set up my account correctly, you can see my first crude attempt at http://www.mediafire.com/file/q10zd56hbc8ytdb/ViestursRobot-annotated.pdf As you can see, I took liberties in naming the components:-) Regards, Kent ------------------------------------------------------------------------------ What Every C/C++ and Fortran developer Should Know! Read this article and learn how Intel has extended the reach of its next-generation tools to help Windows* and Linux* C/C++ and Fortran developers boost performance applications - including clusters. http://p.sf.net/sfu/intel-dev2devmay _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
