Re: First team with swerve drive?
 

Now that you have reopened this discussion, I can enter what I forget to add before. Wildstang has always referred to this drive system as "crab" as that is the term camera dollies use. King Crab is a good choice for infinite rotation.

COTS Slip Rings are legal this year under <R40>.

Re: First team with swerve drive?
 

2783 EOT made a "unicorn drive" in 2009.


it had 4 pods. each had 1 cim coaxially driven (by way of a thin gates belt) and next to the cim was a globe for steering (also connected by a gates belt). each pod had 2 rover wheels, for a total of 8 wheels. steering position was determined by 4 analog encoders. no dead zones.

by definition and posted examples, this might have been the first "unicorn drive"

not bad for a rookie bot?

i do not have much in the way of good pictures. I can get some good ones tomorrow (it is still used as a demo bot).

I do have a couple from the Mt. Washington FLL regional (tickets were raffled for chances to drive it). They are attached.

Upon my move to the team, i was shocked that they built it as rookies. I surely thought that it had been done by a veteran team earlier (coxiaxial 4 wheel independ. swerve), but according to this thread this may have been the first. go figure.

Re: First team with swerve drive?
 

Was it programmed to be holonomic (all three degrees of freedom independently and simultaneously controllable) ?

Re: First team with swerve drive?
 

if what you mean is arcade drive (one stick does f/b and l/r, the other controls rotation), then yes.

if not, it wasn't, but the programmer is good enough that he could have if he wanted to. hardware wise, it is the "unicorn drive".

Re: First team with swerve drive?
 

Yes, it sounds like Unicorn. You mentioned that the steering angle sensors were analog encoders. Do you remember what the make and model number was?

Also, did your team ever post any technical information about the control algorithms?

Re: First team with swerve drive?
 

We certainly weren't the first, but 226 had a "unicorn" drive last year. I believe it was a belt driven coaxial system.

Re: First team with swerve drive?
 

as far as i know no data was published. the signifigance of the bot was never really noted on the team.

they do have solidworks archives of the pod modules... and the engineering mentor who donated the use of his shop has a spare pod to it...

they do not know how special the bot is. they will tomorrow. Actually, the code for it may be lost... we are looking for a copy so we can convert it to CAN bus (yes, it is jaguar based. all 10 of them.)

the encoders are US digital analog encoders, model MA3-A10-125-B. they have a 1/8" shaft, with ball bearings. the cables are hand braided to reduce noise.

the nice thing is to make it fit on the shelf for storage, the top part of the bot is off, giving a nice view of the drivetrain.

Re: First team with swerve drive?
 

Independently steered? How many Globe motors?

Re: First team with swerve drive?
 

4 globe motors.

Re: First team with swerve drive?
 

That makes the fact that it passed inspection the strangest part of all. Only 2 Globes were legal to use in 2009.

Re: First team with swerve drive?
 

funny... 1024 used 4 globes for their crab that year.

Re: First team with swerve drive?
 

1024's crab drive in 2009

The front wheels were steered independently and the back wheels were linked.

2 Globe motors (front steering)
1 Window motor (back steering)
2 Fisher Price (drive)

Hope this clears things up

Allison

Re: First team with swerve drive?
 

As Larry said,

in 2009 we (2783) used a unicorn drive. Here is a run down of the specs:


4 CIMs
2 Globe
2 Fisher Price w/globe gearbox
8 rover wheels
4 analogue absolute encoder
8 Gates Belts
9 Jags


Originally we did have the code & CAD published but in got lost in the many revisions to the website. Also, being rookies our organization skills weren't that great so we are looking for the FINAL code we made right now so we can covert the drive system over to CAN.

I am looking in our picture archive on our web server for some pics right now. Will post if I find them.

Re: First team with swerve drive?
 

Here are some pics of our 2009 crab drive named "Mac"

www.kyeot.com/photoViewer.php

NOTE: These pics were not orginally taken to show off the modules. We took them because we had to make some frame modifications between boilermaker and the Championship in Atlanta

2783, Engineers of Tomorrow

Re: First team with swerve drive?
 

thanks Austin... I though i saw a couple FP's down there... yay, the school filter hasn't blocked CD YET.

sorry for getting 1024's drive wrong... i rembered 4 motors... obviously i remembered wrong!