The images on this page are related to a Tri-Star Wheel project that I've been working on for a while.
I got the bug to try this after running across Cynde Callera's Tri Star Wheel page
which has a lot of great information on this cool idea.
Here is some more background and design information that I have gathered on this concept.
The interesting thing about a tri-star wheel is its ability to climb over obstacles and watching something with wheels climb stairs is pretty amazing.
The first group of images is of a tri-star wheel proof of concept model using LEGO 20x30 wheels. This particular transmission design is not very robust but it shows the components pretty well. These are organized kind of like an instruction set - although backwards. Some are just different views of the same thing to help see some feature. The neat thing about this design is the way the differential transfers power from rolling mode to stepping mode when an obstacle is encountered.
December 1996
One other possibility is to use a track on a tri-star wheel. This is mentioned in the US patent on my background and design information page. This is a first attempt at a tri-star track. The angle in the extension elements was needed to fit the meta-wheel to the fixed track length. I have yet to get a good working drive train built into this but I thought it was interesting enough to add to this page anyway.
March 1997
The next group of images are from two early tri-star wheel/transmission/motor sub-units.
November 1996
This group of images are of revision 1.0 of the complete vehicle with four sets of tri-star wheels.
The vehicle could step over small obstacles at this point but still needed more OOMPH to climb stairs.
January 1997
The next bunch are of the revision 1.1 which has a little more ground clearance and some extra belts and pulleys to give it more OOMPH. This thing can now climb stairs!!!
January 1997
February 1997
MOVIE of REV 1.1 climbing stairs (~2.5 MB .avi)These images are of the current state of the model (revision 1.2) which has four of the newer 'mini-motors' installed in place of the earlier motors.
The gear reduction internal to the mini-motors enabled the removal of the extra belts and pulleys installed in rev1.1.
November 1997 Modification - images are more recent.
There is still a clearance problem associated with this vehicle design. It cannot climb over the top of a stairway without interference. Here is a sketch of this problem. There are many ways to fix this. The easiest way would just increase the ground clearance through the center by moving the transmission components elsewhere. Another more interesting solution would be to add two more sets of tri-star wheels in the center. This could be rather interesting...
