pic: Uber 3.0

[kajeevan]

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[Chuck Glick]

As a former driver and build team leader, I would highly recommend you re-evaluate your choice of gearing. While 16ft/s may sound nice, it is often hard to control for an inexperienced driver. It is a nice speed for a high gear in a shifting drivetrain, however for a 1 speed like you have designed, aim for the 8ft/s - 12 ft/s range. It is a good range to be in and your driver will thank you.

Other than that, nice cad. Looks great.

Did you use JVN's design calculator? and if so what current pull are you getting off of that setup?

Looks nice! The only thing is like what Chuck said, 16 fps is cool, but for us drivers, it takes some getting used to, especially if that's the only speed available to us. Personally, I prefer around 12 fps for rough driving, such as competition driving, since most of the time you must be able to swiftly maneuver around the 5 other robots on the field.

[dodar]

You guys have to remember though, that is 16ft/s as is. This is only the base, you have to remember that there will be close to 100-110lbs more on this after a competition gets announced which would probably slow it down to around 13ft/s.

[AdamHeard]

Originally Posted by dodar

You guys have to remember though, that is 16ft/s as is. This is only the base, you have to remember that there will be close to 100-110lbs more on this after a competition gets announced which would probably slow it down to around 13ft/s.

The weight won't slow it down one bit, the friction in the drive will however.

He could be quoting 16 fps as the number after frictional losses as well, that's what we usually do.

Either way, 16fps is too fast for single speed in most modern games. Maybe it would have been okay in 05, and depending on your role this year as well. You could get pretty roughed up by a solid defender though.

[Brandon Holley]

Reiterating what others have said, for a single speed, 16fps is probably a bit too quick (whether its theoretical or actual). If you do eventually go for multiple speeds, 16fps (actual) is actually quite beneficial.

This past year we geared for an actual speed of 18fps (~22fps theoretical). It was just a tick too high for our liking. In the future we'll probably shoot for 16fps actual.

Looks good though. Keep improving.

-Brando

[Hawiian Cadder]

We geared our robot for 14.4 feet per second this year, and it was way, way fast. it was pretty controllable while it was moving in a straight line, but turning took a long time to get used to. The only reason to gear so high, would be if you had more motors in the drive-train (6 or even 8). That way the torque at the wheels stays roughly the same as a slower robot, and you can control the speed with software (our robots from the last 3 years used the thumb button on the joystick to half all motor output values.)

[AdamHeard]

Originally Posted by Brandon Holley

Reiterating what others have said, for a single speed, 16fps is probably a bit too quick (whether its theoretical or actual). If you do eventually go for multiple speeds, 16fps (actual) is actually quite beneficial.

This past year we geared for an actual speed of 18fps (~22fps theoretical). It was just a tick too high for our liking. In the future we'll probably shoot for 16fps actual.

Looks good though. Keep improving.

-Brando

When doing your drive calcs at such high speeds, you should also check the time it takes to go a certain distance over the range of gear ratios.

If you had done this, it really would have emphasized that you guys just went a bit over the point where acceleration tanks on 4 CIMs.

We started doing this a few years ago, and it's totally changed how we gear our robots.

[Akash Rastogi]

Looks good! Very similar to something I recently drew up, however I had shorter flanges and the outside driverails had the flanges facing in. It also looks like your inside rails and outside rails are different parts, if you can keep the entire chassis to two unique parts, it'll cut down a little prep time for your fabricators, it will also provide another bearing mount for that output shaft of yours. (which I would extend out and support at the end, unless your gearbox is designed with this in mind and you mount your drive wheels closer to the inside rail).

edit: I really like the electronics mount you've got.

[Chris is me]

I would lower the speed down to 12 FPS after friction or lower. This isn't traction limited and you won't be pushing anybody but it is a competitive single speed for a driver with practice and good code.

[Mr. Lim]

If Kajeevan asks me for 16 fps, I give it to him... .

After 5 years piloting an FRC robot, I guess 12 fps just doesn't cut it anymore, eh?

I have to ask, why did you go single-speed? Did you just find that you didn't use low gear enough to justify it? Spinning on axis, even with the 3/16" rocker, seems like it would be an issue...

Speaking of the 3/16" drop-centre, is this based on what you saw from your drivetrain last year? I know we upped our rocker a bit, but I don't think we ever got it as high as 3/16". Do you know of any other teams running this amount of rocker?

Would you be willing to share CAD files? I have a few students who would, no doubt, be interested in gaining inspiration from your work.

Who is your sheetmetal sponsor?

Are you building this in the off-season?

My favourite part: 1" of GROUND CLEARANCE

Looks great Kaj! I think Riddhesh will have a good time piloting this thing around in the future...

P.S. I don't see any encoder mounts... your former electronics mentor is disappoint... smh

[Billfred]

This year, 2815 was geared around 14 on the CIMple Boxes. I think it's the fastest robot we've built in practice*, but we only went for it because we had a veteran driver who's been with us since our rookie year. If we had rookie drivers, I'd probably have adjusted the sprockets to make it closer to 12.

I'll ask another question: How are you planning to mount a manipulator onto this design? There are plenty of valid choices here (not a trick question, promise!).

*Granted, Lunacy and Breakaway weren't really known for their high-speed driving...

[Chris is me]

Originally Posted by Mr. Lim

I have to ask, why did you go single-speed? Did you just find that you didn't use low gear enough to justify it? Spinning on axis, even with the 3/16" rocker, seems like it would be an issue...

It really shouldn't be. Our single speed drivetrains have turned very easily above 10 FPS. It takes a lot to make turning an issue with a proper 6WD.

[kajeevan]

Mr.Lim you are correct I just never used low gear often enough to justify 2 speeds. I would always go around rather than threw a bot it just seemed faster and when we did play defense it would be positional and in the rare case T-boning which was only needed for last second events and not long periods of pushing. Also I'm sure Riddhesh of all people can mesh speed with finesse after 09's performance.

The 3/16'' drop will be a test if it doesn't yield favorably then we'll go back to 1/8''.

Encoders are on the gearbox under the electronics board

Sheet metal sponsor is Sable Metals.

Yes this is going to be the summer project hopefully to start next week and of course I'm willing to share my CADs I'll email them over.

For manipulators depends on the function I'm sure it won't be difficult.

[Colin P]

Originally Posted by Chuck Glick

As a former driver and build team leader, I would highly recommend you re-evaluate your choice of gearing. While 16ft/s may sound nice, it is often hard to control for an inexperienced driver.

I'm going to go out on a limb and say that a team with a CADer this good should have the resources to pull together an experienced drive team. If they do this over the summer, they'll have all the time in the world to practice.
Plus they could always just run their drive at 75% and have a turbo button.