pic: Omni Robot



Robot im thinking about trying to make over the summmer, uses andymark omni’s and banebot motors

This is a really cool design nice work. It looks like the frame is made of Lexan or is that just a product of the rendering?

Also whats the green thing in the middle?

It is a cool design. It would be pretty darn expensive though. Victors are 150 dollars atleast and the omni’s are not cheap. It would be pretty nifty to see this thing in action

-Vivek

looks like the green thing in the middle might be a battery cell pack.

It is made out of 3/16 lexan, the green thing is a 10 D-cell 12v 10AH battery pack… ill give more details later i gotta go finish my term paper lol

If this robot does not have to be FIRST legal, then why not use HB-25’s instead of victors. They work just as well, but are only 50 dollars.

HB-25 Link provided for aforementioned speed controller. (We have enough Vic’s)

Nice design. It looks like it’d be fun to drive. I think we have plenty of Victors in the shop.

Depending on the motors used, using HB-25 speed controllers could be an expensive mistake, since HB-25s have about 37% less continuous current capacity than Victor 884s.

Lexan can also allow for a good amount of “flex” in the frame, which can be good with this style of drive, along with mecanum also.

Yes, victors are expensive, but when can get them for free because you have so many around the shop, they’re the best way to go. That’s why he has the blue 60 mm fans on there. The ones he found don’t have fans. I’ll leave the rest of the explaining up to Max. Haha.

Yeah, make sure to use a healthy supply of cross-bracing in between each layer to minimize that flex. A Lexan chassis is very feasible, you just have to make a good, sturdy design and then follow through in manufacturing. Goodluck!

also the fact that they wont fit in between the bottom two plates if they have the stock fans on there… but yeah we already have the victors so thats no problem, the biggest problem is where to get the lexan water jetted lol

This mostly depends on the gear ratio they’re using. With omnis, you have less traction due to friction in general due to the rubber used typically being more slick than traction wheels, so it’ll be easier to spin out rather than stall on carpet. If the robot is geared for 25 feet per second you could run into problems with this (that number is an example, I don’t know the exact threshold off-hand but you could use JVN’s drivetrain calculator and the coefficients of friction off of AndyMark’s site to estimate it. Or do what I do and forget every time so I draw the same free body diagram each time and solve the same equation.)

Since it is an omni-directional drive system, it should be relatively easy to get out of a situation where you are stalling motors.

That said, lukevanoort has a good point, when using the HB-25s using some 30A breakers is a very good idea to protect your investment. Remember the breakers for the Victors, too, I’d say.

By the way, how fast is this thing supposed to go?

If you cant get waterjetting done easily, something like this could be done relatively well with a bandsaw and jigsaw and a wonder file. It would just take longer and not quite as smooth, but it would work.

Our team builds our entire robot out of polycarbonate. It builds a good chassis, and it looks cool.
Also, make sure you have a way to stop the wheels from spinning. I was the driver this year and we had an omni bot like your design. Trust me, it is really hard to drive, especially if you have no way of stopping the wheels.
Joey

you have one too many wheels…:wink:

but it definitely looks cool.

Team 857 Kiwi Bot

That said, lukevanoort has a good point, when using the HB-25s using some 30A breakers is a very good idea to protect your investment. Remember the breakers for the Victors, too, I’d say.

Breakers are always good, but based on the picture the overall stall/current load should be pretty light. The weight of the proposed robot should be low.

Trust me, it is really hard to drive, especially if you have no way of stopping the wheels.
I’d put the braking jumper switch on the Victors to the on position.

If your actually looking at this type of drive train for the season I would definitely suggest building this to do some software developments because while it may seem uncontrollable when you first build it they can be made very stable.

Don’t take the first spin on it and dismiss it right away. They are hard to get to be easy to drive but the process is rewarding and you will get a fast, fun bot to drive. It takes more than the breaking jumper on the victor.

very impressive.

I use code written by Arthur Dutra that was posted here as the basis for an omni control system. It works well out of the box. Can you post your code, since it sounds like you’ve put lots of work into it?