Chief Delphi - Effective Drive Base

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Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- Technical Discussion (http://www.chiefdelphi.com/forums/forumdisplay.php?f=22)

- - Effective Drive Base (http://www.chiefdelphi.com/forums/showthread.php?t=79910)

JosephBurns35

14-01-2010 09:31

Re: Effective Drive Base

Quote:

Originally Posted by Al Skierkiewicz (Post 898821)

Joe,
Please be careful in suggesting this or implementing something that violates the robot rules. You can't have metal in contact with the carpet as part of your regular drive design.

this i not what i ment in the sample with woody and dean thay showed the plastic and bunge cord things on the robots by the weals they can also be used as somthing to slide you across the bump to prevent hanging up

GaryVoshol

14-01-2010 09:48

Re: Effective Drive Base

Quote:

Originally Posted by edison (Post 898826)

can you tell me how to post cant find it we are registered and all
thanks

Post what, and where? Obviously you've figured out how to post on ChiefDelphi.

brentmcjunkin

14-01-2010 10:31

Re: Effective Drive Base

Quote:

Originally Posted by dustinjeremy2k (Post 896555)

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.

trilogy2826

14-01-2010 12:26

Re: Effective Drive Base

Quote:

Originally Posted by edison (Post 898826)

can you tell me how to post cant find it we are registered and all
thanks

Edison,
I've seen you post this same question in at least four other threads. It is usually bad form to ask the same question multiple times, especially in different threads. I've seen your question was answered multiple times. Are you still having issues?

carbuff2228

14-01-2010 13:48

Re: Effective Drive Base

Quote:

Originally Posted by Alexis Howell (Post 898741)

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.

yeah with meccanum this can help your strategy allowing you to be super manuverable and get away from defensive bots

Iceman1330

14-01-2010 19:42

Re: Effective Drive Base

It surprising how little conversation there has been here regarding how much a particular drivetrain will limit ball interaction mechanisms.

With a drivetrain which covers an entire side of a robot (6WD, 8WD, tread) you largely lose ability to manipulate balls on that side. (owing to bumper height and ball incursion rules) With a 4WD system (mechanum, holonomic, swerve, or tank with modified CoF) a mechanism can exist on any side of the robot.

To example this I've been mocking up a prototype bot designed to be able to guard the goal.

with 4WD you can park it in front of a goal, raise a shield, and utilize a kicker which extends between the wheels. Should you need to get to the other goal your already oriented to do so. High CoF wheels in the rear provide shoving power and increased turning while the front wheels with moderate CoF keep the robot in a line and add to pushing power. A gearbox + motor for each wheel allows for dynamic power shifting between the different CoF wheel sets.

While much discussion has been devoted to the maneuverability of crab, holo, and mechanum, a 4WD using the kitbot frame,wheel drop downs, and wheels with different CoF (roughtops and modified kit delrins and or rubbers) you should have more than enough maneuvering for most teams. (not to mention the cost and complexity advantages)

With regards to high siding a robot, with a 4WD system and a bottom plate, without any modifications you can and will high side.

However if you install a simple textured drum in the middle of the frame which extends slightly below the skid plate and drive it with a window motor you can effectively crawl to a point where at least one set of wheels gains traction again.

hipsterjr

14-01-2010 20:09

Re: Effective Drive Base

We tested two of our traditional 6 wheel chassis that preformed very well in '07 and '08. Need less to say, six wheel bots do not like the bump. After fighting just to get on top of the bump, we knocked out a wheel coming back down.:eek: So we are going back to the articulating 8 wheel drive that we developed in '04. Hope this helps anyone still designing.

joek	15-01-2010 20:37

Re: Effective Drive Base

Quote:

Originally Posted by CraigHickman (Post 898413)

I would recommend looking at the WildSwerve (look at the Andymark website) if you're interested in doing a swerve. However, if you aren't confident in the design principles behind a crab, I would not recommend undertaking it this late in the season.

they're out of stock

joek	15-01-2010 20:45

Re: Effective Drive Base

Quote:

Originally Posted by Shawyan (Post 897808)

(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

15-01-2010 21:02

Re: Effective Drive Base

Quote:

Originally Posted by joek (Post 900070)

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?

joek	16-01-2010 14:39

Re: Effective Drive Base

Quote:

Originally Posted by Chris is me (Post 900076)

What in the quoted post is prohibited?

the quote of the post i'm quoting

whatabouteve

16-01-2010 15:05

Re: Effective Drive Base

Okay Let me explain this. I am from an experienced team that doesn't use swerve drive.

In this game your swerve drive will be destroyed by the sharp angle of the ramp and the load it will be required to carry.

On this note you need to modify the long wheel base to navigate the bump with 2 wheels, however it may be benificial to add an additional wheel to increase the "stuff" you can cram under your chasis.

I really wanted a wide chasis with a 22" wheel base which would serve the same function as a 3rd wheel with a narrow chasis.

The mercana drive thought about will not allow you to easily navigate the bumbs since we have seen this at a local college autonomous competition.

Don't yell at me its just food for thought.

buildmaster5000

16-01-2010 15:12

Re: Effective Drive Base

Quote:

Originally Posted by CraigHickman (Post 898413)

the WildSwere will not work going over bumps because there is a plate that is about 1" above the ground, and will get stuck on the bump before the wheel can make contact. My team is doing 6wd because of this problem (and our programmer doesnt want to have to figure out a swerve drive in 6 weeks)

Akash Rastogi

16-01-2010 17:07

Re: Effective Drive Base

Quote:

Originally Posted by buildmaster5000 (Post 900492)

the WildSwere will not work going over bumps because there is a plate that is about 1" above the ground, and will get stuck on the bump before the wheel can make contact.

Modified modules + modified and creative frame. ;)

CraigHickman

16-01-2010 19:47

Re: Effective Drive Base

Quote:

Originally Posted by buildmaster5000 (Post 900492)

I never said a Crab would be a good idea, nor that it would make it over the ramp. It would be possible to make a crab that can climb. Heck, it's FIRST! Teams have proven it's possible to make almost anything!

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