I have been researching the possibilities for omni-directional or holonomic wheels for LEGO robots. An omni-directional or holonomic wheel is one that can roll not just backwards and forwards, but sideways as well.
While these are often used on robots with three wheels where all three rotate at different rates allowing the robot to go in any direction,
I am interested in using these on a rover that can employ differential steering smoothly without skidding.
There are several different options that one can consider. LEGO purists may consider making their own omni-directional wheel designs out of only official LEGO parts. Another option is to purchase manufactured omni-directional wheels. These come in two classes: those that are designed to be LEGO compatible, and those that are not LEGO compatible. In the latter case, one would have to construct some kind of coupling mechanism to enable the wheel to connect to LEGO parts.
Here are some of the options that I have found.
Omni-Directional Wheels Constructed from LEGO Parts
Omni-Directional LEGO Wheels by Xander at Bot Bench
These wheels use the LEGO pulley to get a six-fold symmetry. Each “wheel” uses 12 LEGO wheels. For archiving purposes, here are three pictures. Please visit Xander at Bot Bench for larger images and more details.
This amazing tank by Peer Kreuger also sports omni-directional wheels made from LEGO parts
The Omni Bot v2 by jason701802 also sports omni-directional wheels
LEGO-compatible Manufactured Omni-Directional Wheels
This LEGO-compatible wheel is made by the School of Robotics
Rotacaster makes a LEGO-compatible omni-directional wheel:
Rotacaster is also coming out with a new design
Rotacaster also produces several non-LEGO compatible designs.
General Manufactured Omni-Directional Wheels
Mecanum Omni-Wheel Designed by Bengt Ilon in 1973 at the Mecanum AB Company
Damon WH-01 Omni Directional Wheel (hexagon hole)
(Outer Diameter:60mm, Inner Diameter:11mm, Material: Nylon)