pic: FRC3880 - Tiki Techs - 2015 Prototype Drive

[TikiTech]

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[Tyler2517]

That looks like you have a lot of extra weight in motors and gear box's are you sure you will need that much power in your drive train.
Why the 4 independent gear boxes?

[nathannfm]

Originally Posted by Tyler2517

That looks like you have a lot of extra weight in motors and gear box's are you sure you will need that much power in your drive train.
Why the 4 independent gear boxes?

The only way I could see using 4 separate gearboxes (assuming you want all those motors) is if they were fully COTS. If you are making your own plates you might as well optimize it.

Also, if that frame outside the wheels is not supporting the axles you could replace it with standoffs between the wheels (to comply with bumper rules) and move the drive rails out almost an inch on each side.

[waialua359]

Originally Posted by nathannfm

Also, if that frame outside the wheels is not supporting the axles you could replace it with standoffs between the wheels (to comply with bumper rules) and move the drive rails out almost an inch on each side.

I'm with you on this. With a smaller footprint the last 2 years, you could acquire more space to work with inside the drive rails area. Because our drive base is modulated using standoffs and plates, we were able to run our chain inside to add even more space AND have the access to the chain, sprockets, etc.


I like the hexagon shape. I'm assuming its to "help" get out of T-bone situations, if necessary?

[Sohaib]

Are you sure you have enough power?

[Oblarg]

Not so sure what I think about the 8-motor, 4-gearbox setup. Looks really heavy - what benefits are there, specifically, over a two-gearbox 6-CIM setup? Keep in mind that you'll also need more air and more tubing and more failure modes to shift with this gearbox arrangement.

[TikiTech]

Originally Posted by waialua359

I'm with you on this. With a smaller footprint the last 2 years, you could acquire more space to work with inside the drive rails area. Because our drive base is modulated using standoffs and plates, we were able to run our chain inside to add even more space AND have the access to the chain, sprockets, etc.


I like the hexagon shape. I'm assuming its to "help" get out of T-bone situations, if necessary?

True more space could be had, though not as much as you think. We did the stand off to bumpers on last years WCD 6 wheel robot.. Was very robust.

http://www.chiefdelphi.com/media/img...9ae90ccd_l.jpg

http://www.youtube.com/watch?v=LfKh6wgLArM

But we still didn't like the bumpers. We used 2 "C" shaped bumpers and was strong but was not to our liking. The idea is to have a one piece bumper drop over and lock on.

Yes this hex frame was done with "Tbone" in mind. Though last year with the 6 cim 2 speed low gear layout we had not many issues with that. Though it should help with getting pinched against a wall..

This is an off season project to try out some odd ideas thought up. The transmissions were done separately so that they can be used in other areas beside just drive.

We like the idea of putting the motor weight over the main drive wheels with the battery centered. Even though this looks like less space it has more internal space than last years robot. The outer frame is 2x1 while the drive tubes are 1.5x3". Gives a great exterior edge for LED ground effects.. FRC Swag!

We were so underweight last year.. Was strange to have to add weight, so we were not concerned with that on this prototype.

The idea is to have the electronics tray nested with the pneumatic shifters and run a plate above all of that level with the top of the frame for a clean deck almost the entire size of the robot. We will have the battery and electronics orientated flat at that time. The vertical battery was added to check the COG. which at the moment is centered on the robot at 4" off the ground.

Not knowing the game this platform leaves a lot to play with.

Of course as soon as the game is released all will change.

If desired I can put up some other views of the drive. There are some newer revisions done and can put up some of those pictures if desired.

Thanks for the comments, keep them coming.

Aloha!

My hex drivetrain is about 28 lbs. How much does this weigh? It looks overkill heavy, and a lot of your custom solutions seem to be poorly thought out. Could you detail your thought process behind the major details of the design?

[TikiTech]

Originally Posted by Oblarg

Not so sure what I think about the 8-motor, 4-gearbox setup. Looks really heavy - what benefits are there, specifically, over a two-gearbox 6-CIM setup? Keep in mind that you'll also need more air and more tubing and more failure modes to shift with this gearbox arrangement.

More power!!

LOL

yes offset by weight.

The idea is to have two driven axels.. and a bit more power with added traction of 8 wheels

We are currently working on a single transmission plate that has two driven axels. We are waiting on our CNC to arrive that will allow us to make the larger more complicated plates. These current plates are done by hand on our small lathe / mill. That is the biggest reason they were separated. That and there was thinking of being able to run front and rear at different speeds. No clue personally why, maybe climbing? Sometime we build off ideas just to do so.

[Abhishek R]

With the chain in the tube, how are you managing to turn with the drive, wouldn't there be a large amount of wheel scrub? Maybe a plan to lathe the Colsons on the outside to be slightly smaller?

I like the hexagon shape. Interesting idea to be able to run the front and rear wheels at different speeds, I wonder what applications you could have with that setup.

[TikiTech]

Originally Posted by Andrew Lawrence

My hex drivetrain is about 28 lbs. How much does this weigh? It looks overkill heavy, and a lot of your custom solutions seem to be poorly thought out. Could you detail your thought process behind the major details of the design?

Poorly thought out is not very helpful..

What do you think is poorly thought out?

Current weight without the battery is 25lbs including electronics shown.

This is our first attempt at a hex frame. Most of this design was based on what materials we have or can get locally. Being in Hawaii, shipping stock material to prototype with is very expensive, so we have to be creative with what is on hand and available. There is nothing here but Lowes and Home Depot. No real machine shops or metal vendors or the like here.

Being a 4th year team we always enjoy learning different ideas, constructively..

Mahalo!

[TikiTech]

Originally Posted by Abhishek R

With the chain in the tube, how are you managing to turn with the drive, wouldn't there be a large amount of wheel scrub? Maybe a plan to lathe the Colsons on the outside to be slightly smaller?

I like the hexagon shape. Interesting idea to be able to run the front and rear wheels at different speeds, I wonder what applications you could have with that setup.

The drivetrain is set up as a WCD with the outer wheels offset (1/8" above the center).

We never had any scrubbing issues with our 6 wheel WCD. The center wheels are 7" apart and should not see much scrubbing. We do have some Omni wheels for the front/rear if tests proves it to be an issue.

Just working on crazy ideas, never know what it could accomplish...

Thanks!

Originally Posted by TikiTech

Poorly thought out is not very helpful..

What do you think is poorly thought out?

Current weight without the battery is 25lbs including electronics shown.

This is our first attempt at a hex frame. Most of this design was based on what materials we have or can get locally. Being in Hawaii, shipping stock material to prototype with is very expensive, so we have to be creative with what is on hand and available. There is nothing here but Lowes and Home Depot. No real machine shops or metal vendors or the like here.

Being a 4th year team we always enjoy learning different ideas, constructively..

Mahalo!

I use the term "poorly thought out" very loosely. It's just part of the vocabulary. What I mean to say is I can't tell your train of thought in this design, and there are many design choices I question because I do not understand the reasoning behind them (hence why I asked about your thought process behind it).

What I see when looking at this frame immediately is the large quantity of gearboxes, and the large quantity of CIM motors. I understand earlier you said you made the decision of the 8 motors for the sake of "more power", but doing the math on my end shows marginal improvements in usefulness that do not seem worth the extra weight nor the risk of blowing the breaker. So I'm wondering what was the in-depth reasoning behind your choices for 8 motors, as well as the initial reasoning for 4 different gearboxes (I know you said you're planning on a new gearbox, but I'm curious about why you thought 4 different ones was the best solution initially).

Also, your frame layout with the 2x1 making the hex on the sides makes me question if you will be able to take your wheels off. For a true WCD the ability to easily remove your wheels is invaluable at times, and it appears like you're sacrificing this ability to shape your frame in this method. Out of all the ways to make a hex shape, why did you choose this one?

Speaking of framing, your 2x1 appears to be 1/8" thick - the more common style for a WCD - so with all of your tubing non-lightened, 8 motors, 4 gearboxes, and colson wheels, I really have a hard time believing that this drive system even without the electronics is 25 lbs. You have almost 20 lbs solely in drive motors, let alone solid 2x1x1/8 aluminum tubing and 4 large gearboxes, and then the added electronics makes it impossible for me to believe this is 25 lbs.

Your constructive iteration is the key to success - I just try to restrain from constructive criticism until I understand the thought process behind the design, so that I can better focus my advice towards the design and the designers.

[Abhishek R]

Originally Posted by TikiTech

The drivetrain is set up as a WCD with the outer wheels offset (1/8" above the center).

We never had any scrubbing issues with our 6 wheel WCD. The center wheels are 7" apart and should not see much scrubbing. We do have some Omni wheels for the front/rear if tests proves it to be an issue.

Just working on crazy ideas, never know what it could accomplish...

Thanks!

Oh, I didn't realize there was a drop. I faintly remember team 118 having to use different sized wheels because they could not enough space in the tube to have a big enough drop with the sprockets and chain. Did you have a solution to that problem or did everything seem to fit inside the tube just fine?

[Gregor]

Originally Posted by Andrew Lawrence

I use the term "poorly thought out" very loosely. It's just part of the vocabulary. What I mean to say is I can't tell your train of thought in this design, and there are many design choices I question because I do not understand the reasoning behind them (hence why I asked about your thought process behind it).

Not sure how poorly thought out can mean anything other than poorly thought out?