Effective Drive Base

[Seat Ninja]

Originally Posted by hipsterjr

We designed these articulating drive pods back in 2005 and have been waiting for a game like this to use them.

(stares with amazement)
...I...WANT...THOSE

[DiehardCybercard]

I'd like to thank everyone for all of their input!

I was hoping this thread would generate a good place for a few people to reference and learn. I've learned a lot from everyone's posts. Thanks all =]

[Shawyan]

Originally Posted by hipsterjr

We designed these articulating drive pods back in 2005 and have been waiting for a game like this to use them.

Wow. Simply amazing drive train.

I believe the best overall drive train is either full holonomic or Swerve drive. This would allow being able to rotate the robot to face the goal, as well as drive in the desired direction. Swerve drive allow the team to keep more motors free for other activities such as a kicker, but still retain the "any direction i want, i go, no worries".

Also, I do not see the reasoning behind why having smaller wheels will make it more difficult to go over the bump, as long as the wheels are extended further down. Though 4 inches may be pushing it.

[Chris is me]

Originally Posted by Shawyan

I believe the best overall drive train is either full holonomic or Swerve drive. This would allow being able to rotate the robot to face the goal, as well as drive in the desired direction. Swerve drive allow the team to keep more motors free for other activities such as a kicker, but still retain the "any direction i want, i go, no worries".

All the strafing of holonomic or swerve in the world isn't worth anything other robots violently push you across the floor (holonomic) or if your drive breaks (swerve)

My personal favorite for this year (not tied to any teams i'm working with) is a hang up between 3 different skid steer designs.

[Alexis Howell]

Originally Posted by Chris is me

All the strafing of holonomic or swerve in the world isn't worth anything other robots violently push you across the floor (holonomic) or if your drive breaks (swerve)

My personal favorite for this year (not tied to any teams i'm working with) is a hang up between 3 different skid steer designs.

But if you had a well practiced driver, wouldn't it be easy to avoid other robots with a holonomic drive base? unless of course a couple of robots decided to go into your field area...

Also, rules say a robot can only be pinned for a maximum of 5 seconds.

Also with holonomic, you can just forget about traversing. If it's even important to your strategy.

[joek]

Originally Posted by Shawyan

(the post he's quoting) Wow. Simply amazing drive train.

I believe the best overall drive train is either full holonomic or Swerve drive. This would allow being able to rotate the robot to face the goal, as well as drive in the desired direction. Swerve drive allow the team to keep more motors free for other activities such as a kicker, but still retain the "any direction i want, i go, no worries".

Also, I do not see the reasoning behind why having smaller wheels will make it more difficult to go over the bump, as long as the wheels are extended further down. Though 4 inches may be pushing it.

and prohibited, unless they posted the designs, due to rule R25, but you could post the CAD files on this thread to make the design COTS

[Chris is me]

Originally Posted by joek

and prohibited, unless they posted the designs, due to rule R25, but you could post the CAD files on this thread to make the design COTS

What in the quoted post is prohibited?

[Jstack14]

Originally Posted by hipsterjr

We designed these articulating drive pods back in 2005 and have been waiting for a game like this to use them.

How heavy is it? and how well does it turn?

[dustinjeremy2k]

In response to several comments and questions regarding my reasoning for my dislike for 6WD and tread designs as a climber... Understand I'm not suggesting that they cannot climb. Of coarse they both can be extremely effective on inclines. But their MAIN advantages are massive weight distribution on unstable surfaces (tanks with treads in sand) and maintaining contact with extremely unpredictable terrain (rovers) when used with a suspension system.

So, my original post was under the heading "Basics"... and I was not considering anything with a suspension a basic design. In a basic (kit-bot) configuration the 6WD and tread option give you the same see-saw effect as you crest the peak of this games "bump". Not exactly the picture of stability. Toss in a reasonably high CG (needed for clearance in a static system) and the likelihood that your weight distribution will be biased in one direction to some extent, and well, I'm not interested. Two points in contact are by definition more stable…

We tested this out this evening as well (on a kitbot rolling chassis) and that's all I needed to see! Throw it together and see for yourself. Good luck.

[Kevin Sevcik]

Originally Posted by Nathan2974

I just wanted to point out that the actual grade of the bump is approximately 38.7 degrees (or something to that effect) using simple trigonometry based on the height and width provided by FIRST.

Sir, you should perhaps examine the official field drawings for the bumps that will be on the field. The chamfer on the rib that supports the bump happens to be 10 1/4 high and 10 1/4 wide. Simple trigonometry tells me that the bumps FIRST is going to be building will be at an angle of 45 degrees.

[dtengineering]

Originally Posted by Kevin Sevcik

Sir, you should perhaps examine the official field drawings for the bumps that will be on the field. The chamfer on the rib that supports the bump happens to be 10 1/4 high and 10 1/4 wide. Simple trigonometry tells me that the bumps FIRST is going to be building will be at an angle of 45 degrees.

Thanks, Kevin... before I read your post I was thinking... "NOOoooo... we didn't screw up when we built 45 degree angle bumps... did we?", and actually went and re-downloaded the drawings to check.

I've attached the relevant image here.

45 degrees is correct... and wow... it sure looks scarier in person when you see an actual bump first hand than it does when you look at the drawings.

On a seperate note, a student drew up some drawings very much like Madison's this afternoon... and while I don't think ground clearance will be an issue, so long as teams plan for it, CoG is certainly going to be.

After watching teams like 254 climb the ramp, drive sideways across the ramp, basically jump off the ramp and show off what a low CoG can do in Aim High, however, I'm pretty convinced that we can build an even lower CoG for this game. In fact, I wouldn't be surprised if some of those old Aim High robots have already made it over the bump....

I think the really maneuverable robots this year will not only be able to "get air" off the ramp, but to climb a flight of stairs.

Jason

Edit: And as for making a 4wd robot with big wheels turn... AndyMark might be able to help out a bit http://www.andymark.biz/am-0104.html

[MrForbes]

Madison's 8wd picture is looking pretty good...and similar to what we came up with when comparing 6 and 8 wd bots going over the bump.

You can get the CG way lower with 8wd than you can with a 4wd bot that clears the bumps. And playing with raised end wheels does neat things to steering ability.

[roboticWanderor]

Originally Posted by Kevin Sevcik

Accelerating off the backside of the bump will probably spare you the faceplant at the price of an even rougher landing.

i think some fast robots are going to be surprised to see how much air they can get flying over that bump, such instances will make for some cool pictures for sure, structural integrity of the chassis not withstanding.

[brentmcjunkin]

Originally Posted by dustinjeremy2k

I'd like to encourage teams to draw lots of diagrams, mock up rolling chassis, and think about the assumptions you are making before designing a "drive base".

Basics
4WD skid - simple, effective, stable climber. If it's designed to stand a chance in a pushing contest, it won't be very maneuverable.
6WD skid / tank tread - a bit heavier, more moving parts, NOT a very stable climber, much more maneuverable, still good at pushing (Usually the best "compromise" chassis, but not this year).
Omni / Holonomic - very versatile, simple, maneuverable, but you're on roller skates, and can't climb well (or at all).
Crab / Swerve - similar to above but with superior traction, superior handling, more complex, many moving parts, not likely to be a good climber. Does not (usually) rotate the chassis efficiently which could lead to more complex (multi-sided) game mechanisms.

I think the best drive systems will be some sort of hybrid between two of the basics. I would NOT use a tread or a crab to climb... good luck to those who try it! (And do you really need to climb anyway?) If you do, you might want to bring a big tool box to the competitions!

Enjoy!

Ok first of all tanks just crawl over cars in war. which means it should be able to go up the ramp. a skid steer would be effective with the right wheels. but i think that the tanks might actually be dominant in this game.

[Ram Raman]

Would four wheel drive be effective, would it be able to make it over the bumps, how would the turning be?