"Lobster" - Mecanum wheel car drives in any direction

Here is something I've been wanting to make for a long time, finally made
possible by an amazing design for "Mecanum wheels" due to Zblj over at
<http://www.eurobricks.com/forum/index.php?showtopic=46945 Eurobricks>.  

<<http://www.brickshelf.com/gallery/aeh/Lobster/small/1-sm.jpg>>

<http://www.youtube.com/watch?v=Qbtlbtkp6-w>

<http://www.brickshelf.com/cgi-bin/gallery.cgi?f=452391>

Mecanum wheels are similar to "omniwheels" except that the small wheels are
oriented diagonally.  This allows a vehicle that can drive forwards in the usual
way, but can also move sideways or turn by rotating the wheels in different
directions.  What makes this one different is that it is controlled by a system
of differentials (similar to an add/subtract mechanism but a little more
complicated). This means it can be controlled by just 3 motors: one for
forward/reverse, one for sideways, one for turning. With a lot of effort I was
able to get the mechanism quite compact - it uses only 4 differentials. I
usually settle for pure functionality, but this time I made some limited attempt
at styling too...  Enjoy!

Alexander

<<http://www.brickshelf.com/gallery/aeh/Lobster/small/6-sm.jpg>>

<<http://www.brickshelf.com/gallery/aeh/Lobster/small/7-sm.jpg>>