[Madison]

Originally Posted by Crazy Ivan

The slots are a good feature, but I would say that an active suspension is almost without a doubt nessisary. Some sort of ridged adjustment only works if the playing surface is compleatly level and smooth (unlike the floor of the Georgia dome that is full of warps). And even if all the wheels apear to be touching, just a small amount of slip with one wheel can cause you drive train to go funky. Even with our active suspension, it took a good hour to align and even then it only strafed strait in only the right hand direction, with a small arc to the left.

Unfortunatly we don't have any pictures of the wheel pods up close, but I'll give my best try to describing them. With both systems I mentioned before, one end of the wheel assembly must be on some sort of hinge or pivot (we did this with a removable steel pin). The other end of the wheel assembly was held by screws going through the ridge part of our frame, and threaded into the wheel assembly with cylinders of gum rubber inbetween the frame and wheel assembly. A similar system was used, only with 3 inch pistons at 45 degree angles.

The other method of suspention you can use (as I belive you alluded to earlyer) is the system team 190 used in 2005, where the wheels were ridged, but it was there frame that actually had one big pivot in the middle.

Hope this helps!

I was afraid that an active suspension would be necessary. While certainly not too hard to achieve, the added complexity and additional weight hurts the practicality of the design.

On your chassis, were the bolts that ran through the rubber cylinders riding in slots? It seems like they'd need to because the module pivots on the opposite end, but it's hard to see from the photo you posted -- which is otherwise enormously helpful. For as much as people are fascinated by these drives, I can't seem to find very many photos.

Could you describe a bit more about what you mean by 'aligning' the drivetrain?

Originally Posted by Mike Nawrot

Awesome design. Nice and simple. There are a few improvements I see possible. Using 25 chain instead of what appears to be 35 will save some weight, because it will allow you to achieve a smaller pitch diameter on the drive sprocket, which will allow you to use a small sprocket on the wheels to maintain the same ratio, resulting in less material in sprockets and a shorter length of chain.

We have a lot of material for #35 chain on hand already, including a pretty good variety of sprockets and a few dozen feet of chain. It's also really easy to track down aluminum sprockets for this pitch from sources like IFI or AndyMark and they both tend to have much shorter lead times than places like Stock Drive Products. I'm okay with taking on some extra weight here if it means fewer headaches.

Also, the rollers on you mecanums are all aligned in the same direction, and last I checked, they should oppose eachother to actually achieve omnidirectional motion. That's just a small detail though.

Yep. I'm just too lazy to create a mirror of the wheel.

Also, I'm a bit concerned about the chain on the rear wheels, since when the wheel assembly pivots, the chain will be forced to twist in a bit of an unnatural fashion.

Me too! I rationalized it by saying, "that's what prototypes are for," but since it seems like an active suspension will be very important to making this work correctly, I'll likely correct this in the next iteration. I could include it among the pivoting subframe, but then that starts to become very large and it's hard to mount additional mechanisms to it. I was hoping the chain would have enough play in it, since I don't imagine the subframe will raise or lower more than about 1/4".

Thanks for the continued discussion everyone.