pic: Ramp Video

[JesseK]

Yep Joe, Update #3 today also green-lighted it. I really look forward to seeing this design in action! Be sure to post some videos of it during competition.

[betsy888]

Originally Posted by Chris is me

There's a ball differential so if the front and back wheels are spinning in opposite directions, the omnis don't turn.

Thanks so much for the feedback. Our team has decided against having an articulating 6-wheel approach due to the complexity and the limitations of our team but I must say I'm still curious. How does your ball-differential work? From what I understand of ball differentials, there is one drive gear and 2 driven axles. So I assume your center omni wheels are on the driven axles. But you have 2 driving chains coming from the omni wheels and only one drive gear. Do you have a special type of ball differential? Can you explain a bit more?

Thanks again! Good luck with your design. Congrats on getting the green light in Q&A!!

[joeweber]

Originally Posted by betsy888

How does your ball-differential work? From what I understand of ball differentials, there is one drive gear and 2 driven axles. So I assume your center omni wheels are on the driven axles. But you have 2 driving chains coming from the omni wheels and only one drive gear. Do you have a special type of ball differential? Can you explain a bit more?

The Mechanum wheels are driven, the chains drive sprokets on the ball differential, between the sprockets are steel balls that are inside a round flange with holes for the balls. The flange is attached to the drive shaft with the omni wheels. Pictures are on our wesite http://www.team1322.org/ideas.htm

[the man]

Is that the 45degree angle of the ramp? it looked to shalow, and you should build a real bump if possible because it is much harder to test with out the real thing if you know what i mean.

[joeweber]

Originally Posted by the man

Is that the 45degree angle of the ramp? it looked to shalow, and you should build a real bump if possible because it is much harder to test with out the real thing if you know what i mean.

That picture is from one year ago. You can view a video http://www.youtube.com/watch?v=jQMcw4QNCLI

The video ramp is a 45 degree ramp but we had to cut the corners for the low ground clearence of the 6 inch wheels. We will be using 8 inch

[DynamiteHack]

Originally Posted by joeweber

As you can see from the drawing the frame is stationary on level ground and does not articulate. When it goes over the ramp the drive system articulates but the frame remains solid. ( the frame is where the bumpers are attached).

Correct me if I'm wrong, but wouldn't the sections connecting the omnis to the mountings have to get longer/shorter as it tilted? Adding height to the slope gives a longer line.
Unless the mountings can tilt in and out?

[joeweber]

Originally Posted by DynamiteHack

Correct me if I'm wrong, but wouldn't the sections connecting the omnis to the mountings have to get longer/shorter as it tilted? Adding height to the slope gives a longer line.
Unless the mountings can tilt in and out?

The rear virtical strut will pivot at the frame.

[betsy888]

[quote=joeweber;902964]The Mechanum wheels are driven, the chains drive sprokets on the ball differential, between the sprockets are steel balls that are inside a round flange with holes for the balls. The flange is attached to the drive shaft with the omni wheels. Pictures are on our wesite http://www.team1322.org/ideas.htm

I think I know the source of my confustion. I assumed the omni wheels could move independent of each other. Now that I see your ball differential drawing and photos it looks like they are attached to the same shaft so must move together. If this is true, why do you have 2 omni wheels at each location, why not just one?
As always, thanks and good luck!

[EricH]

Originally Posted by betsy888

If this is true, why do you have 2 omni wheels at each location, why not just one?

It provides a smoother ride than having one single omni at each point. A number of teams have tried single; I believe most of them switched to double at some point.