4 vs 6 wheels (what to choose)

[HarveyAce]

We in team 3329 are apparently still in the process of choosing our drive system. We are debating 4 or six wheel drive, and I am leaning toward the 6 wheel because of the balance and weight distribution of our robot, especially if we are planning on making something to reach up to the top pegs. are those factors to take in with the selection of the number of wheels? It also may help to let everyone know that we are using almost the same design layout for the chassis as the kop, but we are re fabricating it in 1/8 in aluminum box tubing, because we had issues last year with the c-frame warping, and our robot was EXTREMELY light last year. So 4 or six?

[JamesCH95]

Nowhere in the OP was "mecanum" mentioned. I believe the question is 4wd tank vs 6wd drive tank. I'd go with 6wd tank as it comes well packaged in the KOP c-base. If you decide to go 4wd have two of the wheels be slick or omni wheels, so that your robot can actually turn.

Good luck!

[Bernoulli]

in all reality both of these have strengths and weaknesses however the way you go about your design ie: tank, omni, mecanum, swerve, crab will really determin which set up along with what you want it to ba able to do ie: manuvure, agility, strength, pusshing power, etc etc etc however it seems alot of teams have had success with a 6 wheel drive using 4 mecanum and 2 sticky wheels however its all up to how u want your robot to perform

[JamesCH95]

Originally Posted by Bernoulli

in all reality both of these have strengths and weaknesses however the way you go about your design ie: tank, omni, mecanum, swerve, crab will really determin which set up along with what you want it to ba able to do ie: manuvure, agility, strength, pusshing power, etc etc etc however it seems alot of teams have had success with a 6 wheel drive using 4 mecanum and 2 sticky wheels however its all up to how u want your robot to perform

Surely you mean omni wheels? I've never seen a 6wd robot with 2 traction wheels and 4 mecanum, nor have I ever heard of one.

I may sound picky, but there is a big difference between a mecanum wheel and an omni wheel.

[DinerKid]

A huge part of picking a drive train is what you want it to do and how you plan to build around it. Last year we wanted to build a goalie-bot. We decided quickly that we wanted to have the robot oriented so that we could block with the wide side. We then decided that a wide kicker would be a good idea. For this design mecanum was a just. we wanted to be able to drive really fast between the two goals but also strafe forward and backwards in order to drive up to the ball in order to kick.

For this year if you are confident that your programmers will be able to write line tracking code that will get you in position to score maybe you go with a 6 wheel rocker.

If you think you will end up manually positioning the bot to score then you have a bit more to think about. On one hand you can spin a 6 wheel rocker to make adjustments (to a certain point) while mecanum will easily strafe to do the same thing.

There isn't really any way to say which one is better. It depends on what you are trying to do and how you are trying to do it. Thats what makes this engineering.

~DK

[Mike Rizzo]

One of our Mentors, Clem McKown, created a PowerPoint in regards to drive trains models and it may help you with which drive train to choose.

http://wiki.team1640.com/images/b/b0/Drive_Lesson_3.pdf

[Chris is me]

Originally Posted by nckureghian14

Cons: Lacks ease of maneuverability

Does it now? I've seen hundreds of six wheel drives and they all seemed maneuverable to me.

I'm tired of people essentially saying "since mecanum is more manuverable, 6 wheel drive must be significantly less manuverable". Strafing does not equal manuverability, or vice versa.

[MattC9]

Originally Posted by Chris is me

I'm tired of people essentially saying "since mecanum is more manuverable, 6 wheel drive must be significantly less manuverable". Strafing does not equal manuverability, or vice versa.

...you have no idea of how much i have to fight this...

[548swimmer]

I'd say 6 wheel rocker. With the rock you don't have to worry about "skipping" during your turns.

[BrendanB]

Originally Posted by 548swimmer

I'd say 6 wheel rocker. With the rock you don't have to worry about "skipping" during your turns.

I second this idea. 6wd with the center wheel dropped 1/8 of an inch, and if you are using the kit frame the center hole is already dropped 3/16 of an inch.

[EagleEngineer]

"Cons: Lacks ease of maneuverability"

We actually did a test, and realized that the 6-wheel drive is actually more maneuverable than the Mecanum.

[BJC]

I will agree with the others: 6 wheel drive.

[Team 2811]

I would say mechanum because that is what our team is using and it works really well but the 6 wheel has really go maneuverability too if you implement the drive system right.

If you use 2 rubber wheels for friction as the two center most wheels and then you use omni wheels for the front 2 and back 2 then you have great maneuverability and better control. However you aren't as maneuverable as with mechanum.

With the six wheel drive train, you have a better resistance from being pushed. My experience shows that the mechanum can be pushed if you have a weaker but faster gear ratio.

Hope this helps

[Team 2811]

Originally Posted by nckureghian14

Pros and Cons:

4 Wheel Mecanum

Pros: Maneuverability

Cons: Slower

Not true. My team had a four wheel mechanum drive train last year and it was really fast in every direction. However, it is true that going straight is faster than going in a different direction.

[Teched3]

IMO, mechanum is a difficult task in programming during the build season, even for very experienced teams. Stay within your capabilities. Wheels are available through AndyMark, so the mechanical requirements can be met if you have the funds. Use the offseason to develop new systems and concepts. I have been in this fo 16 years, and am still learning. Just my opinion.