02-03-2009 17:52

Swttrt224

Re: pic: Team 2022's Drivebase

What a BEAST of a drivebase....some genius must of invented that...

oh wait, HA, I invented that... lol :-)

It's amazing that we were easily able to push around Wildstang's 4 CIM swerve with traction control AND Winnovation's tank with traction control...

02-03-2009 17:57

gorrilla

Re: pic: Team 2022's Drivebase

so only 1 cim for all 4 wheels? or one for each wheel?

02-03-2009 18:05

big1boom

Re: pic: Team 2022's Drivebase

1 CIM total

02-03-2009 18:07

gorrilla

Re: pic: Team 2022's Drivebase

wow, what transmission are you using?

02-03-2009 18:48

Lil' Lavery

Re: pic: Team 2022's Drivebase

Where else were you using your CIM motors?

02-03-2009 19:03

big1boom

Re: pic: Team 2022's Drivebase

Standard toughbox transmission, then chain sprockets set up as follows 15:9:bevel:11:22

We only have 1 other CIM and it is on the power dumper.

02-03-2009 19:08

Lil' Lavery

Re: pic: Team 2022's Drivebase

Why only use one CIM on the drive then? Were there weight or space issues?

02-03-2009 19:13

big1boom

Re: pic: Team 2022's Drivebase

We did the calculations, and 1 CIM would provide more than enough torque to skid the wheels. But then when it was tested at Midwest, we have just enough torque to get nearly maximum acceleration. But we do not have enough to spin our wheels. This means that we are always in static friction. So we actually have better traction than bots that have to use sensors and traction control code. This is why we were able to push around Wildstang, who have 4 CIM's and active traction control.

We could throw a 2nd CIM in. But as it is now, the CIM does not overheat, we have maximum traction, and fairly good acceleration. So why change?

02-03-2009 19:34

CJmango

Re: pic: Team 2022's Drivebase

Wow, that is awfully insightful. I'm always a fan of bigger and more powerful but this year I think you've got the right idea. All of these other teams are spending their energy developing software to limit their beefy drivetrains, instead you avoid designing a beefy drivetrain in the first place.

The active traction control is still a disadvantage because in most cases, in order for it to activate, the wheels have to slip. Pushing the slip boundary like that makes it easier to push them if you're solidly in static friction.

That picture also blows up nicely, but I don’t think we can see the bevel gears in the housing. Do you have any pictures from the assembly process?

Kudos on a crazy cool design.

02-03-2009 19:41

big1boom

Re: pic: Team 2022's Drivebase

Thanks for the complement.


I will try and find a picture of the inside of the box.

02-03-2009 19:49

big1boom

Re: pic: Team 2022's Drivebase

Pretty big image so I will just link to it.
http://i43.tinypic.com/nd6a90.jpg
Here is a small version.


That is the best picture that I can find. We didn't take any intentional pictures of the wheelbox's.

02-03-2009 20:28

spage

Re: pic: Team 2022's Drivebase

Just because your driving me up the wall Swttrt224 by taking all the credit I would Like to lay down the blame for this drive train and answer others questions.

Firstly, this drive train is the result of a study swttrt and others including myself did last year. The math for the gear ratio with some real world tweaking is swttrt's, the actual drive train that was cut by a student on the team and framing around the drive train that was built by big1boom was all Cadded by me. As such why I am extremely disappointed when all the credit for this drive is taken by one over zealous member.

An additional note that I would like for other members of my team to understand is that they must remain gracious professionals when on these forms and need to stop gloating. Is it true that this drive train has yet to find a match that can push it as adequately, yes. Is it true that this robot did not win the Midwest regional, yes. Is it true that my members have just explained exactly why we have so much traction, yes. Do I expect that because of their posts we will have lost our advantage, yes.

Since they have been so forward about our robot I feel that It is only right to post up some CAD's I drew. These Cads where used to build our drive train. I will try to explain what was used for what.



This is the original idea before we found out that Caterpillar could not produce any parts for us due to economic issues.



So we made a frame that looks like this with the same chain and electrical Ideas as previous.



we actually milled these with a 20 year old cnc that we got working 2 weeks before ship and taught ourselves how to cut. Not the notches that allow our bit to make right angles where we need them. - this was milled by both 1/8 inch and 1/4 inch end mills. Thanks to my sophomore team that learned how to run the machine we finished on time.





Those last 2 should give you an idea of the bevel gear set up, the plates are placed so that they keep the bevel together while taking into account the bushings.

The aluminum is just 1/8 in thick, and thank goodness cause it helped keep the weight down.

The lazy suzans are from mcmaster.- a note to my sophomore's as I will me graduating this year, use a smaller chain next year.

I had a great time cadding this, and It really helped modularize our build cause it stated the exact placement of the ball system and electrical.

02-03-2009 20:32

spage

Re: pic: Team 2022's Drivebase

How much more practice will it take before I am able to get a job with some drafting company?

14-03-2009 21:03

Kat Kononov

Re: pic: Team 2022's Drivebase

scott, i'm really impressed with your CAD drawing. don't lose this skill.

15-03-2009 00:16

spage

Re: pic: Team 2022's Drivebase

thanks- we got lots to people looking over our drive train at Wisconsin - they liked that it used easy to find parts- Post season plan is to teach the sophs to cad-

09-04-2009 20:10

keehun

Re: pic: Team 2022's Drivebase

Wow, amazing drive base. I am wondering, will the CAD files ever be uploaded?

Thank you,
Keehun,
Captain, Team 2502

10-04-2009 18:00

JHSmentor

Re: pic: Team 2022's Drivebase

So - did you drive this as a crab drive or did you switch between all wheels pointing in the same direction (crab) and having the front / back wheels pointed in opposite directions? Or - did you just drive with the front and back wheels turning oppositely?

I ask because our bot this year was a somewhat similar design but probably a lot more simple (we just don't have the equipment to do anything more fancy). We had Ackermann steering for the front wheels and Ackermann for the back wheels separetely so they would turn opposite each other. our experience was very similar: we could push any other bot around easily and in many cases, 2 bots at a time (no traction control used either). Having properly designed Ackermann steering allowed the wheels to point in the direction of the turn at all times so there was no slip required to turn.

10-04-2009 21:38

big1boom

Re: pic: Team 2022's Drivebase

We had crab drive for most of the time, however, whenever the trigger on our steering joystick was pulled, and the stick twisted, the wheels pointed opposite directions for turning.

The reason we were able to maintain traction, was because we had less power than other robots. This made it so that we never broke into dynamic friction.