pic: DS Swerve on the field [Archive]

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Racer26

09-04-2010, 16:08

[cdm-description=photo]35499[/cdm-description]

Akash Rastogi

09-04-2010, 16:15

keehun

09-04-2010, 16:18

I thought that there was a rule saying that you could only operate in one defined orientation, which means that you couldn't flip over and keep on driving (you had to right yourselves up somehow before moving?)

I just checked the rules and I couldn't find what I read before that got me to think about not being able to invert and keep on driving, but I distinctively remember reading a rule and deciding as a team that we wouldn't make something like that... but how did it do? Crab drive... wow awesome! But... Crab drive X 2? Even more epic! :P

EricH

09-04-2010, 16:28

Keehun, the GDC ruled it legal via Q&A, providing all other rules were met.

Akash, they thought they'd tip. After not tipping at all in Waterloo, they removed the second drivetrain in favor of other functionality.

Racer26

09-04-2010, 16:29

Akash,

In our initial analysis of the game, we thought that going over the bumps was going to be alot more flip-prone than it turned out to be. The robot was supposed to be designed to only have 2 stable configurations (on its wheels).

We saw at Waterloo how it behaved (namely, didnt flip, even when we tried), and determined it wasn't necessary, so we took it off for GTR, and made our ball manipulation and hanger substantially better. Anybody that saw us hang in Q8 at GTR should agree.

The top and bottom wheels were all driven all the time, and yes, it required a bit of driver intelligence in the sense that the controls would be reversed when inverted.

EDIT: Also, we thought it would be good fodder for an engineering or innovation in control award.

EDIT2: It should also be noted that in the above photo, the arm is not in its normal position.

Vikesrock

09-04-2010, 16:31

The top and bottom wheels were all driven all the time, and yes, it required a bit of driver intelligence in the sense that the controls would be reversed when inverted.

This issue could be dealt with in code by detecting robot orientation using sensors. An accelerometer detecting gravity should be able to do this fairly simply I believe.

Racer26

09-04-2010, 16:35

Yes, it could have, but we didnt have the weight for it, and since inverted was only a configuration intended to get us to a bump and flip over again we didnt think it necessary.

JamesCH95

09-04-2010, 16:36

Very cool, though it doesn't look like you have a kicker "on top" or a hanger "on bottom" so you'd lose those functions once inverted? I guess it'd be better than being turtled though.

Akash Rastogi

09-04-2010, 16:37

We saw at Waterloo how it behaved (namely, didnt flip, even when we tried), and determined it wasn't necessary, so we took it off for GTR, and made our ball manipulation and hanger substantially better. Anybody that saw us hang in Q8 at GTR should agree.

Ah gotcha. Well, at least now you have 2 seperate swerves to play with! :)

Racer26

09-04-2010, 16:38

For those that are interested, it can be seen in its GTR configuration behind Roberta Bondar in this picture: http://picasaweb.google.com/patfair/GreaterTorontoRegional2010#5456766171620254514

It lost the upper wheels, and gained a much improved (and lighter) arm.

Racer26

09-04-2010, 16:41

Ah gotcha. Well, at least now you have 2 seperate swerves to play with! :)

Not really Akash,

The units were tied together, it can be seen better here:

http://picasaweb.google.com/patfair/WaterlooRegional2010#5453787665933385058

A better pic of it + Roberta:

http://picasaweb.google.com/patfair/GreaterTorontoRegional2010#5456766107170969314

Akash Rastogi

09-04-2010, 16:55

Not really Akash,

The units were tied together, it can be seen better here:

http://picasaweb.google.com/patfair/WaterlooRegional2010#5453787665933385058

A better pic of it + Roberta:

http://picasaweb.google.com/patfair/GreaterTorontoRegional2010#5456766107170969314

Still very cool though.

PAR_WIG1350

09-04-2010, 17:08

I hate being "that guy" but I'm just wondering, what was the point of doing an inverted drivetrain?

This is not supposed to be a slight towards the creativity of this or the fact that you technically built TWO fully functioning swerve drives, but I just don't see the point considering how low your CG is and that chances of flipping perfectly onto the opposite side would be rare to none. Was it purely for the fun and challenge or did you think it would come into play? I'm sure the learning experience for the kids was pretty awesome though!

-Akash

!350 did something similar with skid steer and did flip perfectly onto the other side in Boston, and if you don't, 2 wheels are still touching the ground at all times so you could drive into the bump or a wall to flip the rest of the way.

Lil' Lavery

09-04-2010, 19:42

Very cool, though it doesn't look like you have a kicker "on top" or a hanger "on bottom" so you'd lose those functions once inverted? I guess it'd be better than being turtled though.

I believe their intent was simply to drive it back to the bump and flip themselves back into normal configuration after flipping over.

Racer26

09-04-2010, 21:14

I believe their intent was simply to drive it back to the bump and flip themselves back into normal configuration after flipping over.

That was exactly the intent. You will also notice the lack of anti-3" penetration gear on the topside.

Kellen Hill

09-04-2010, 21:34

Team 101 had a similar idea in Chicago but they only had a "standard" four wheel drive. It was neat to watch the top set of wheel spinning on top of the robot. They also had an extra ball magnet on the top in case they flipped over.

I remember them flipping over at least once if I remember right. If I spent time on that kind of drive, I would try to make sure I flipped over at least once just to see it work.