Drive Train and wheels

[Evil Asian]

is it better to have to back drive wheels or four??? and is it better to have the tracktion wheels????

[Tottanka]

Obivously it is always better to have 4 driving wheels, but it cists you with much more weight.
Traction wheels are just different they arent better nore worse, they are just used for differebt purpose.

[GBIT]

personally, 811 has done this for 2 years now. we have 4 wheel drive with 2 traction wheels and 2 omni wheels. it gives you tons of pushing force and you can turn on a dime. especially with tank steer.

[Evil Asian]

thank. we have two drive wheels and they dont work that great

[lukevanoort]

Define better. 296 won the championship last year with a 2WD using casters, however their partners, 217 and 522, had extremely high traction 6WD and tank tread systems, respectively. Both worked well. Basically you need to analyze the game and what you need for it. Last year we were rather high traction (coeff. of friction of about 1.3) this year were about 1.0, are both of these valid choices? Yes. We made this choice for a very specific reasons, 1) We felt no need for more traction 2) We're playing offensive this year instead of last year's defense and most of all 3) This amount of traction is nearly ideal for our drive system, since we spin our wheels at just a tad over 40A draw to our motors, keeping us from tripping breakers.

In, short, can a robot with a coeff. of friction of .7 be as effective as one with 2.0? Depends on what you want. Similarly, can a robot with two driven wheel best one with six? Yes. Can six best two? Yes. There is no magic bullet, or universal best design with drive systems. (Although one could make an argument for swerve drives being the universal best, they are rather complex to implement successfully) There are many more factors than just traction wheels or not. Search for posts on drivetrain design if you really want to get into it, especially those made by Joe Johnson, JVN, and Paul Copioli.

[Billfred]

Originally Posted by Evil Asian

is it better to have to back drive wheels or four??? and is it better to have the tracktion wheels????

The generally-accepted ideal is to have all parts of your robot that touches the floor driven. However, you can still get around a field otherwise; the matter comes down to your particular needs and constraints.

[fluffy]

our robot this year has separate cims per wheel, for a total of four. wheels are the traction wheels and we have deployable casters for turning
provides a robot that goes pretty fast, can push our mentor around, and can spin nicely in circles

[Evil Asian]

thank you all for help

[wilsonmw04]

As a first year team I was just planning on running a 4WD Robot with the KOP wheels. With help from 1086, we turned it into 6WD bot with the KOP wheels. We used the KOP frame and set the center wheel 1/4" below the other wheels.

During the VCU regional, we were very manuverable, ran about 7 ft/sec and we had GREAT pushing power. I would highly recommend this same setup to anyone.

[Evil Asian]

thanks. that might help us.

[Ericgehrken]

Team 195 is using a two CIM Motor two speed transmission with a six-wheel tank style steering with Andy-Mark traction wheels.

[vadyr]

as many of you know, or dont know, 103 has been legendary for their use of casters and two drive wheels in the rear....and this gave us our famous spin move, which somehow gets passed onto drivers magically...haha.....but this year....WE SCRAPPED IT! we went to an ultra light but ultra powerful and fast 6 wheel drive system....we can still turn on a dime and do our spin move, but we are a lot stronger and a lot more stable. in years past we were pushed around like nobodies business, but our agility kept us in the game...now we have the ability to push and be agile...what the heck more could you want from a drive system?! our drive is a gearbox with 3 wheels in each, powered by a 2 speed pneumatically shifted andymark gearbox....total weight of the drive system...nada....im not sure on the numbers, but i believe each gearbox and transmission weighed about 22 pounds...so thats only 44 pounds for the drive system...which could be better, or could be much worse...hehe

[Ben Piecuch]

Many teams stick with a simple 2wd system, as it is cheap, efficient, lightweight and simple to build. However, you've quickly discovered that they are complicated to drive and easily pushed around.

If you are using a common "swivel caster" on the front of the robot, I can offer one quick, simple change to make it drive 100% better. This website, http://www.omniwheel.com offers a "transwheel" that practically eliminates the initial wobble that a swivel castor produces. They are very cheap wheels, and fairly indestructable, and we've used them with great success in the past. However, they will not improve your power, or resistance to side loads.

YMMV,

BEN

[Evil Asian]

thnks. right now we are trying to think of a way to make up for the lost of wight. we are a light wight class and i was thinking that the drive train could help make it up