pic: Drivetrain Concept

[echin]

loading photo ...

[Tyler2517]

Look like a really sweet idea. Only question is will it strafe straight?

[asid61]

Looks good. I would be partial to a regular 6WD with the cims in that configuration (for space), but omni is cool too.

How is this going together? Screws? ARe you sure that you can assemble it right?
What's the material?

43lbs is pretty heavy. There's probably a problem somewhere.

[Tyler2517]

It has a lot of motor weight 6cim/2miny cims..... its a lot of weight in motors.
Even more then a swerve would be.

[bkahl]

Originally Posted by Tyler2517

It has a lot of motor weight 6cim/2miny cims..... its a lot of weight in motors.
Even more then a swerve would be.

Your Motor weight would be there anyway.



Otherwise, looks great. Just a couple questions...

1. Are those modules made of lexan? Kinda hard to tell on the render... If so, what have you done to prevent flexing?
2. Is the slot in the box large enough to fit both gears in?

[echin]

Strafing should be straight, and it should be possible to do anything that a swerve can do as well.

Assembly would either be bolts or rivets, but I am thinking mostly rivets. The frame is made by 1" x 2" aluminum box tubing, and 1" x2" u channel.

For weight, roughly half is in motors, and I could drop a set of CIMs and change the reduction pretty easily to reduce weight. Also, I'm planning on adding some kind of lightening cutout to all of the frame members, which should cut down the weight some as well.

[Gdeaver]

Pre 2014, I would say the frame members are way over sized and using thinner metal and a little redesign on the frame would have been recommended for weight. After watching the frame failures in 2014, I would not say it is over built. Still there are other methods to absorb the impact forces with less weight.

[BrendanB]

Keep in mind that there are 3 additional CIM motors in this setup that you normally won't see on standard butterfly/slide drives. To drop some weight we can remove two CIMs and one mini CIM without sacrificing much as a majority of them are run with 4 CIMs. 2013 and 2014 have been the only years we've seen 6 CIMs and 4 mini CIMs in the kop so robots have been getting heavier just in motor weight alone. Our past year's drive was 6wd six CIM shifters came in around 40lbs so this base gives us more for a few more pounds. Remove the center slide module and you can remove more weight and it becomes a standard butterfly.

This is also a lot easier to build, program, and drive compared to a full on swerve drive so its a more feasible project for us to try out with room to make it lighter.

Nice work Eric!

[Kevin Leonard]

I'm not gonna lie this drive looks beautiful.
I'd love to see it in action- is this a planned off-season project?

[Madison]

A few things that don't pass the "that doesn't feel right in my gut" test --

1. Change the channel to rectangular tubing everywhere. Channel is much less rigid in torsion than rectangular tube.

2. The strafing omniwheel is not well-supported in the frame. You're removing a lot of material from the 2x1 cross-members for chain clearance and leaving very little wall where the U-shaped cutouts are. The weight of the robot, when it's sitting on that strafing wheel, is supported almost wholly across the four thin gussets you're using to couple those 2x1 cross-members to the rest of the frame.

2a. That all presumes, of course, that you're actuating the strafing wheel downward. It's unclear if that's the case. Otherwise, I'd be concerned that the normal force acting on that wheel alone will not be sufficient to move the robot sideways.

3. Gusset the joints more to give you some additional support against wracking to whole frame into a parallelogram.

4. It's hard to be sure from this view, but it looks like you're mounting the CIMs against the outer flange and race of the bearings. That gives me the willies.

[R-Garst1625]

How does the center drop down wheel work? Is it one wheel or two wheels?

[Orion.DeYoe]

This is impressive. I really like it. I'm assuming you want suggestions so here are a few:
1) I would change the framing to 2 x 1 x 1/16 tubing (someone pointed out to me that this is lighter as well as stronger than pocketed 1/8th material).
2) The structure for the middle module could be made simpler. I'm not sure which part is spring loaded so I may be missing something. You seem to have several pieces of flat bar (3/16?) acting as stiffeners across several of the frame members in the middle. This could be redesigned to use sheet metal or standoffs to save weight and space.
3) Aluminum gears? I'm assuming that's what you're using but just checking.
4) I would take your high gear speed down to 16 fps. Just my preference after running a 20 fps drivetrain this past year. We made the change to 16 fps and really liked it. That was with 4 cims though so you could save weight by taking 2 out or leave the ratio the same and using 6.

[jimbo493]

Originally Posted by Tyler2517

It has a lot of motor weight 6cim/2miny cims..... its a lot of weight in motors.
Even more then a swerve would be.

Not in my team's current design, we have a Cim and a MiniCim powering the wheel, and a bag powering the steering. the whole thing is 4cims 4 minicims, and 4 bags...

[Chris is me]

Originally Posted by jimbo493

Not in my team's current design, we have a Cim and a MiniCim powering the wheel, and a bag powering the steering. the whole thing is 4cims 4 minicims, and 4 bags...

Just be aware that this configuration would be illegal under the 2013 and 2014 rules. You're allowed to use up to 4 total of either mini-CIMs, BAGs, or a combination of the two. You weren't allowed 4 of each.

[echin]

How many teams actually use a H drive? I know that 624 and 148 do, but how many others are there? From watching match videos of these teams, it looks like they primarily use their center wheels for getting out of defense, but do not use them continuously.

Also, has anyone ever tried using a CIM as part of a spacer? If it was possible to mount something to the outside frame piece that touched the back of the CIMs, it would act as several large spacers and make it much more difficult to bend the frame in.