4wd wide base: Looking for videos, experience, comments and thoughts

[Leav]

Hello,

My first reaction to the game animation was:

• Need to collect balls? wide base might be a good idea. (more room for roller)
• Need to have 3 robots on the ramp, or more room for error with 2 robots? wide base might be a good idea. (takes up less space when driving forward)
• Need to go over a bump? 4wd could be a good idea (thinking of breakaway here, each wheel goes over independantly)

Most (all?) wide-base chasis' I've seen have been in 2009, but that doesn't give me a good idea of its manuverability.

so I'd love to get some:

• videos of 4wd wide base on carpet with non-slick wheels
• comments from people who have implemented 4wd wide drive
• comments on the general idea of using 4wd wide base in 2012

Always hoping to learn somthing new!
Thanks!
-Leav


summary of links from this thread:

• frc1918 had 4wd in 2010 (actually 8wd, but only the outer 4 touch the ground) closeup video, and BlueAlliance page for that year. Thanks Ike!

[IKE]

1918 had a wonderful 4x4 wide in 2010. It was a great machine, and one of the best of 2010 overall.

http://www.thebluealliance.com/team/1918/2010

[quinxorin]

Originally Posted by Leav

Hello,

My first reaction to the game animation was:

• Need to collect balls? wide base might be a good idea. (more room for roller)
• Need to have 3 robots on the ramp, or more room for error with 2 robots? wide base might be a good idea. (takes up less space when driving forward)
• Need to go over a bump? 4wd could be a good idea (thinking of breakaway here, each wheel goes over independantly)

Most (all?) wide-base chasis' I've seen have been in 2009, but that doesn't give me a good idea of its manuverability.

so I'd love to get some:

• videos of 4wd wide base on carpet with non-slick wheels
• comments from people who have implemented 4wd wide drive
• comments on the general idea of using 4wd wide base in 2012

Always hoping to learn somthing new!
Thanks!
-Leav


summary of links from this thread:

• frc1918 had 4wd in 2010 (actually 8wd, but only the outer 4 touch the ground) closeup video, and BlueAlliance page for that year. Thanks Ike!

I am thinking 4WD is the way to go this year, but am not sure whether to make it long or wide. We did a 4wd wide in 2004, 2009, and several other years, and it works great. It's nice and mobile (though not as much as an omnidirecitonal drive train like mecanum). The increased width between the wheel lines decreases the friction while turning, while retaining the same pushing force and sideways friction. The axis of rotation is centered in the middle of the robot. It's good for pushing too, if done correctly. In 2009, we had traction control, and the combination of drive train, sensors, and software allowed us to basically push any robot we chose. It was nice. The only concern is the chance to fall over backwards if accelerating suddenly. That can be remedied by making sure heavy components are at the bottom of the robot.

[davidthefat]

I am very torn on this game. My original intent was to be a shooter/balancer due to the new qualifying ranking system which weighs autonomous higher. But considering how hard that actually is to make it in consistently, I changed my mind to a defensive/feeder/balancer bot. That will hinder our performance in the ranking, but potentially give us a better chance of actually winning matches. So the wide 4 wheel would be great, but to minimize slippage, I was thinking of going wide 8 wheel, but that won't go over the bump.

I must say, I have a dilemma here...

[Leav]

Thanks a lot for the input and comments so far.

David: I agree that the 4wd seems very tempting this year!!

I'd like to refocus this thread towards examples from past years and comments from people who have built or used the 4wd wide drive train...
thanks!

[Mk.32]

Our team on kick off day built the 4 wheel wide version of the kit frame.
Photo/Video here: http://www.youtube.com/watch?v=AnIGj...ature=youtu.be
In a short test of driving it around, it seemed pretty nimble and quick.
Might gear it lower however.
We did have it go over a 2x4 seemed to be okay.

[viperred396]

Originally Posted by Mk.32

We did have it go over a 2x4 seemed to be okay.

Vid?

[Rabajaka]

Another advantage to going with 4 wide is that the 6 wdr with the middle wheel being lower then the other ones making the bot rocking back and forth when the bot is shooting

[Nick LaPosta]

That would depend on where your weight is centered at. The ball isnt going to create much rock if any if your weight is centered low and to the front.

Also on the four wheel drive, my team had a four wheel drive in 2010 and we had trouble steering. You want to try to keep your wheels as close together as possible while still being stable. Otherwise you end up dragging the wheels across the floor making it difficult to turn. That was with the standard rubber 6 in" wheels.

[SenorZ]

Originally Posted by Mk.32

We did have it go over a 2x4 seemed to be okay.

But the barrier is 4x6... do you guys plan on using bridges exclusively? We're looking to do a similar setup but with the 8'' wheels.

[KrazyCarl92]

Our 2010 robot used a 4 wheel swerve drive with 2 modes. One mode is strictly translating in a crab drive mode, but the other is with the wheels straight operating as a wide base 4WD. It uses 6" FIRST wheels. Here's a video of it playing breakaway:

http://www.youtube.com/watch?v=LvHBv...yer_embedded#!

When the robot is moving sideways that won't give you a good idea about the maneuverability of what you are thinking of. But when the robot is moving strictly forward/backward and turning, that is exactly the type of maneuverability you are interested in seeing! It may be tough looking at the video for the first time to differentiate between when its in swerve vs. tank mode, but it's there!