pic: Team 2220 Rebound Rumble Robot (week 5)

[Jedward45]

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[aeniug2]

Looks really nice.
Hmm... Seems like quite a few teams are going for pneumatic wheels this year.
Our team is too far along to switch to them now, but just out of curiosity:
What do you think the advantages of having them will be? and how well does your bot turn with the 4 of em' ?

[frasnow]

Nice frame and drivetrain. I like how the electronics are easily accessible.

That looks like a lot of motors using CAN. I hope you've tested it or had success with CAN in a past season. There were lots of discussions last season about CAN problems. We had issues running 6 motors on CAN last year. In our testing it looked like there was too much communication on the CAN bus. We took the drive motors off CAN and made it so we didn't send messages to the two motors we left on CAN as much. Our issues may have been caused by using serial instead of 2CAN. We're waiting for teams to have glowing reviews of CAN this season (or a future season) before going back.

[ehochstein]

Nice! Thankfully I will not be inspecting your bot this year at the Lake Superior Regional... Haha but I look forward to competing against you guys!

[Jedward45]

Originally Posted by Wiifi

Nice! Thankfully I will not be inspecting your bot this year at the Lake Superior Regional... Haha but I look forward to competing against you guys!

We've dedicated a lot more mentors and students to developing a clean electronics setup. They've done a nice job... hopefully inspection will be a little easier this year.

[ehochstein]

Originally Posted by Jedward45

We've dedicated a lot more mentors and students to developing a clean electronics setup. They've done a nice job... hopefully inspection will be a little easier this year.

I agree with you, your robot looks very nice this year! Your robot from last year was still really nice though, it just needed a little extra work. At least you didn't really have to worry about anything breaking your electrical system! If I remember correctly it was pretty well hidden.

[DampRobot]

Will this intake system include a transport to the shooter? It looks like there is a fair amount of distance between the shooter and the system hidden behind the electronics board...

[Alex.q]

In regards to CAN, I believe we tested it on a test board that the programmers were using, but not on the actual robot yet. Can you elaborate on what we should waatch out for with the CAN?

Pneumatic Wheels: they compress with a lot of weight on them, so a center drop of .25 reportedly had too much scrub with the first version (6 pneumatics), hence the omnis. We hope that the short wheel base will help with turning only 4 pneumatics. As for reasons why we used them: traction, shock absorption for hitting the barrier, maybe more reasons.

Unfortunately, our supershifters still have the standard gearing so with 8in wheels, we go a bit fast. We are hoping to reduce this either with the optional gearing or a sprocet reduction to the wheels.

Originally Posted by DampRobot

Will this intake systrm include a transport to the shooter? It looks like there is a fair amount of distance between the shooter and the system hidden behind the electronics board...

The collector is basically a tower with belts that will feed the shooter.

[PAR_WIG1350]

Are you using the flux rings on the motors to protect the leads? I would advise against doing so for several reasons (wire damage due to chaffing, reduction in motor performance, etc.). PVC is a much nicer material for this application anyways.

[aeniug2]

Just thought of this now... Not entirely related, but I have to ask:
How do you use the aluminum extrusions?
Our team bought a whole bunch of it, but no one can seem to figure it out.
We have tried looking elsewhere on CD, but all we can gleam is that there is some sort of special connector we have to use.

We would greatly appreciate any help regarding this...

[Alex.q]

Originally Posted by aeniug2

Just thought of this now... Not entirely related, but I have to ask:
How do you use the aluminum extrusions?
Our team bought a whole bunch of it, but no one can seem to figure it out.
We have tried looking elsewhere on CD, but all we can gleam is that there is some sort of special connector we have to use.

We would greatly appreciate any help regarding this...

ARe you referring to the 80-20 we used on the shooter/electronics tower? 80-20 has connectors you can buy and we also used carriage bolts (squares right under head)that fit perfectly in the slot to mount the electronics panels. Let me know if you want more information on this and I can ask one of our mentors who know more about this to answer your questions. This is our first year using 80-20, so I am sure there are other teams that have more experience with it than we do.

[aeniug2]

I would love more information on it, thanks for offering.
Specifically, where to buy these fabled "connectors"...

[Alex.q]

I might ask one of our mentors to elaborate on this as well, but here is a link to the 80/20 webpage on different fasteners http://www.8020.net/Training-2.asp. I'm not entirely sure which we used.

[Siri]

Originally Posted by aeniug2

I would love more information on it, thanks for offering.
Specifically, where to buy these fabled "connectors"...

80/20 is nice for a lot of things, especially quick adjustments and sliding. Their slides are a little heavy, but you can make your own, too. It's heavy, though, and it can be difficult to keep things in place under shear load.

As for the connectors, you can look up distributors on 80/20, Inc, but we get most of our stuff through Grainger and MSC.

Short overview:
Most FRC applications I've seen and used employ 10xx profiles (1"), mostly 1010 with some 1020 (1012 is cool, too). For these and other profiles, 80/20 makes fasteners that slide into the T-slot slots or can be tapped into the center axis holes. Economy nuts are probably the most common and are used in tandem with other connectors. They're slide-able when loose and can be pretty fixed when the bolt is tightened. (You can indent it a little for the bolt tip so it doesn't move.) We also use corner brackets and gussets, end caps, anchor fasteners and the occasional joining plate, most of which have various versions (multiple holes, shapes, etc). Their rollers are also really nice, though you may want to mill your own brackets for them.

[frasnow]

Originally Posted by Alex.q

In regards to CAN, I believe we tested it on a test board that the programmers were using, but not on the actual robot yet. Can you elaborate on what we should waatch out for with the CAN?

We had lots of issues with the CAN bus just completely locking up. In other words, all of the motors on CAN wouldn't function. During the 2011 build season we tested the individual motors on CAN, but we only tested the entire system on the last build day. There were indications of a problem prior to bagging the robot, but major issues at the regional. The robot would just freeze. By switching the drive motors to PWM, we could still drive, but our arm (on CAN) would lock up. Putting delays between the calls to the arm helped, but hurt our controls. We also discovered noise on the arm's potentiometer was another cause of the CAN bus locking up.

Other teams may have had better success and can tell you how to avoid the problems we had.