Finding Mecanum Wheels

[Creator Mat]

My team is looking into using a Mecanum drive train. However after doing some research we found that normal Mecanum Wheels can't function properly on a sloped surface going side to side. But there is a mecanum variant that can function when when on a sloped surface going side to side. We just can't find where to buy these wheels. The reason we want this type of mecanum wheel is because without them (using normal mecanum wheels from andymark) we can only go over the hump head on with little room for alignment error. So does anyone else know where to buy these versions of the mecanum wheel?

Note: please read this paper (http://ftp.mi.fu-berlin.de/Rojas/omn...eter-Tlale.pdf) for explanation why a normal mecanum wheel can't function when on a sloped surface and for what this alternative mecanum wheel might look like.

Also we did find this type of mecanum wheel here (http://letsmakerobots.com/node/10282) but it is to small for us to use and plus the plastic might not be able to stand up to competition.