This is my first animation using the DUIK plug-in from DuDUF in France. It's really next level and very well featured. Learning how to use it isn't easy though. I would classify this a project for advanced users only. If you aren't careful the whole technique can blow up in your face! Oh yeah, all of the tutorials are in French with subtitles, so that part was fun too. Check out http://duduf.net/ and get the download and documentation.