pic: Chameleon Drive

[DampRobot]

Cool idea. Although I like the concept, I feel like weight might become a bit of an issue. You have to carry around all that plate and bearings even if you never use them.

Also, do you have any plans for bumpers? These tend to get left out in most drive train designs until the end. You may have trouble supporting the bumper to what the manual requires (I believe every ten inches) with the three bearing blocks in a row.

[JesseK]

"Chameleon Drive" implies the thing blends into the background ... yet I totally see all of that drive in all configurations o.O
(Ok, I kid...)

The most basic piece of this 'drive' is the H-frame. Your H-frame setup is very verstatile. However, I don't think the gearbox configurations are. For the 8WD and 6WD tank variants, why not just use the CIMple boxes that come in the KOP? The chain runs are easily tensioned by sliding the transmission, it's lighter overall, c.g. is lower overall, and the sprocket reductions are adjustable so you aren't stuck with purchasing ~$100 in gears just to get the right speed for a given year.

For the slide drive (your bottom pic), you may find that the robot doesn't need to slide sideways as fast as it moves forward/back. If this is what you find, you may be able to use 2 RS-550's (properly geared...) in lieu of 2 CIMs, thereby putting the 2 CIMs back on the outer wheels for better power characteristics during normal play.

[Jon Stratis]

Two thoughts on what looks like a great design:

- For use as a test chassis, how about emulating AndyMark's nano tube chassis and running power between the wheels inside the frame? That way, you could have every wheel slot powered all the time, making swapping drive trains even easier (just pull off one set of wheels and put on another!)

- If you want to use this for competition, keep the weight rules in mind. Swappable systems like this are really cool, but all of the hardware used in every configuration you bring counts towards your weight limit. So, if you plan to swap between traction and omni wheels at competition, you'll have to weight both sets of wheels with your robot, even though only one set will be on the robot at a time. See R03 in the 2012 game manual for specifics (it's been in the manual that way for years, I doubt the rule will change in the future).

[Jon Stratis]

One more thought... why not push the two cross bars towards the outside a bit more, and set them up for 3 wheels each? That would give you the option of using the center for a strafing wheel like you have now, or setting it up for a wide drive base design, with no wheels on the long side.

[JVN]

Looks pretty cool.

A few comments:
1. Figure out your bumper mounting. This is something most people ignore until the "end" but the sooner you think about it the happier you'll be with the implementation.

2. I've found the 6" diameter AndyMark omni-wheels work a lot better when they're run as duallies -- you should consider that for your H-Drive implementation.

3. I believe you're sacrificing some functionality at the expense of versatility. "Jack of All Trades, Master of None." In my experience, it is very very very rare for a team to switch drive styles mid-season. As a result, it might be better for you to CAD several different configuration specific designs, knowing that you'll be able to do subtle things to make them better than this one design that does all of them. If you prioritize versatility enough that you're willing to make tradeoffs (they may be big, they may be small) then you have nothing to worry about. Your mileage may vary.

-John

[IKE]

Very cool design. I agree with a lot of the other commenters that this looks like a really neat and versatile test chassis. I would suggest talking with your programmers about sensor incorporation and programming goals. A chassis like this could go from good to great with good iterative software and driver interface development.
Even if it is a test chassis, the addition of good bumper should enable you to have a defensive sparring partner.

[Peck]

one more comment: where are you putting your speed controllers and other nessesary hardware?

[Akash Rastogi]

Nice first full project, Nate. Here are a couple things you can check out to help you iterate; another person a while back had a similar idea.

http://www.chiefdelphi.com/forums/sh...ad.php?t=95179

http://www.chiefdelphi.com/media/photos/36921

As with the above project, it could be a great project to make in the offseason to test different drives, but it most likely is not the practical design for a competition robot.

Also, this may be a good chance for you to learn how to create configurations of your assembly within Solidworks.

[Garret]

We switched from swerve to Mecanum at the LA Regional this year; this was because we accidentally fried our swerve steering motors when calibrating the PID at San Diego and didn't want to deal with it at LA. We were able to do this very fast because we design our drive train in modules. Each module uses the same of mounting and has everything already built in (except controllers).

I really like a of things about the the OP's design, especially the design around limited manufacturing capabilities. Also, it looks like it should be able to accept mecanum as well because of the corner gearboxes. Great work!

[mikemat]

Just out of curiosity, how much time do you think it would take to change the drive types? It would add a neat dynamic if you could be a 6- or 8-wheel drive for quals, then switch to mecanums or a slide drive in elims so you can triple, or change drives between matches to better suit your opponents and partners.

[Peck]

Originally Posted by mikemat

Just out of curiosity, how much time do you think it would take to change the drive types? It would add a neat dynamic if you could be a 6- or 8-wheel drive for quals, then switch to mecanums or a slide drive in elims so you can triple, or change drives between matches to better suit your opponents and partners.

dude, you would take up your entire weight allowance in just the drive train and be unable to master how the robot drives.

[mikemat]

Originally Posted by Peck

dude, you would take up your entire weight allowance in just the drive train and be unable to master how the robot drives.

If you shipped as pictured in 6 or 8wd configuration, all you would need to bring would be the mecanum wheels. A slide drive would be harder because you would need an extra gearbox and motor controller, but not impossible with 30 pounds. I can't speak for driver training, but judging from the teams that already switch mid season, it isn't impossible to adjust to a different drive.

[EricH]

Originally Posted by mikemat

If you shipped as pictured in 6 or 8wd configuration, all you would need to bring would be the mecanum wheels. A slide drive would be harder because you would need an extra gearbox and motor controller, but not impossible with 30 pounds. I can't speak for driver training, but judging from the teams that already switch mid season, it isn't impossible to adjust to a different drive.

Modular systems are allowed on a robot, but if a robot can have extra configurations--example, two arms that have different functionality--either you stick with one configuration (or do a permanent change and request reinspection) or all the configurations together must be under the weight limit. That's been in the rules for as long as I can remember.

The governing limit here isn't the Withholding Allowance. It's the robot weight. I don't think that most teams would like cutting into the 120# allowance by 15# or more.


However, I think this sort of drive system could be invaluable to a team, not necessarily in competition use but as a practice robot. Build it Day 1, throw a bunch of tests at it to figure out drive base for the year, use as a practice defender or build the rest of the robot on top of it. It's not unheard of for a competition robot to be designed to handle two different types of drivetrain, but only use one in competition.