2 Motors is Faster?!

[artdutra04]

I see no reason to use four CIM motors in a drive train this year.

There isn't really a way in which a team would be torque-limited this year (unless you use the Mabuchi motor); you will be entirely traction-limited. Using four CIMs on the drive is just wasting hundreds of Watts of power.

[Katie_UPS]

Another thing answering your question;
In this game traction is everything. And you want the most traction.
So with the two wheel bases, they both are relitively the same weight (I know weight is added for extra motors and wheels, but I'm talking on a very general level).
So with four wheels, if the weight was 100, each wheel carried 25 pounds (ok, so I know this is a little off, and I don't have enough physics background to properly explain this, but once I'm done, this should make sense), but on the two wheel, each wheel carried 50 pounds, which created more friction which gave it more... power (if thats the right word....)


EDIT: No one really explained that to you, and thats why the two-wheeled went faster (or as my mentors explained)...

[Akash Rastogi]

Originally Posted by Katie_UPS

Another thing answering your question;
In this game traction is everything. And you want the most traction.
So with the two wheel bases, they both are relitively the same weight (I know weight is added for extra motors and wheels, but I'm talking on a very general level).
So with four wheels, if the weight was 100, each wheel carried 25 pounds (ok, so I know this is a little off, and I don't have enough physics background to properly explain this, but once I'm done, this should make sense), but on the two wheel, each wheel carried 50 pounds, which created more friction which gave it more... power (if thats the right word....)

Not necessarily, that's with the assumption that your team feels traction is most important. Even if Dean or Woodie said it doesn't make it true either. There's no defining basis that says that teams want most traction possible in this situation.

[Katie_UPS]

Originally Posted by Akash Rastogi

Not necessarily, that's with the assumption that your team feels traction is most important. Even if Dean or Woodie said it doesn't make it true either. There's no defining basis that says that teams want most traction possible in this situation.

Ok, well, in my mind, on the ride from kick-off to shop, that was the most important thing to me, because I couldn't think of anything else to worry about without knowing the rules/restrictions. And so thats where that comes from.

I should have specified that that was an "In My Opinion" thing.

[paulcd2000]

Because of the extremely low friction (mu=.06), the max acceleration a robot can experience is well below what the two motors can provide, so the max acceleration of a two/four motor drive are the same. HOWEVER, i think the 4 motor drive could have a much higher high speed. However, i don't think you could readily attain it on the field because the field is actually pretty short.

[Daniel_LaFleur]

Originally Posted by paulcd2000

However, i don't think you could readily attain it on the field because the field is actually pretty short.

Nor do I think you want to. Remember everyone that you'll need to stop too, and that also requires traction

[paulcd2000]

Originally Posted by Daniel_LaFleur

Nor do I think you want to. Remember everyone that you'll need to stop too, and that also requires traction

that is a very good point... while refs will be less ready to issue ramming penalties, deliberately ramming into the end wall at high speed is probably still discouraged.
My team considered using raisable and lowerable wheels as brakes, angled perpendicular to the direction of motion.

[Daniel_LaFleur]

Originally Posted by paulcd2000

that is a very good point... while refs will be less ready to issue ramming penalties, deliberately ramming into the end wall at high speed is probably still discouraged.
My team considered using raisable and lowerable wheels as brakes, angled perpendicular to the direction of motion.

Not alloew according to <R06>

<R06>
ROBOTs must use ROVER WHEELS (as supplied in the 2009 Kit Of Parts and/or their equivalent as provided by the supplying vendor) to provide traction between the ROBOT and the ARENA. Any number of ROVER WHEELS may be used. The ROVER WHEELS must be used in a “normal” orientation (i.e. with the tread of the wheel in contact with the ground, with the axis of rotation parallel to the ground and penetrating the wheel hub). No other forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction) are permitted. The surface tread of the ROVER WHEELS may not be modified except through normal wear-and-tear. Specifically, the addition of cleats, studs, carved treads, alterations to the wheel profile, high-traction surface treatments, adhesive coatings, abrasive materials, and/or other attachments are prohibited. The intent of this rule is that the ROVER WHEELS be used in as close to their “out of the box” condition as possible, to provide the intended low-friction dynamic performance during the game

[paulcd2000]

that.... is a good point. i imagine our rules guru would have caught that, but thank you.

[Madison]

Originally Posted by Daniel_LaFleur

Not alloew according to <R06>

<R06>
ROBOTs must use ROVER WHEELS (as supplied in the 2009 Kit Of Parts and/or their equivalent as provided by the supplying vendor) to provide traction between the ROBOT and the ARENA. Any number of ROVER WHEELS may be used. The ROVER WHEELS must be used in a “normal” orientation (i.e. with the tread of the wheel in contact with the ground, with the axis of rotation parallel to the ground and penetrating the wheel hub). No other forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction) are permitted. The surface tread of the ROVER WHEELS may not be modified except through normal wear-and-tear. Specifically, the addition of cleats, studs, carved treads, alterations to the wheel profile, high-traction surface treatments, adhesive coatings, abrasive materials, and/or other attachments are prohibited. The intent of this rule is that the ROVER WHEELS be used in as close to their “out of the box” condition as possible, to provide the intended low-friction dynamic performance during the game

A wheel perpendicular to the direction of travel can meet all of the criteria of this rule. The tread of the wheel is contacting the ground and the wheel's axis of rotation is parallel to the ground.

If having wheels skid sideways violated this rule, wouldn't all teams violate it at some point during a match as they're pushed around by their opponents?

[paulcd2000]

Originally Posted by Madison

A wheel perpendicular to the direction of travel can meet all of the criteria of this rule. The tread of the wheel is contacting the ground and the wheel's axis of rotation is parallel to the ground.

If having wheels skid sideways violated this rule, wouldn't all teams violate it at some point during a match as their pushed around by their opponents?

This may be something that will get updated in future rule sets. I agree that as stated, it doesn't forbid it, but i would be careful about designing a robot that way.

[Daniel_LaFleur]

Originally Posted by Madison

A wheel perpendicular to the direction of travel can meet all of the criteria of this rule. The tread of the wheel is contacting the ground and the wheel's axis of rotation is parallel to the ground.

If having wheels skid sideways violated this rule, wouldn't all teams violate it at some point during a match as their pushed around by their opponents?

In his application, the wheels are purposely not in their "normal" orientation.

[paulcd2000]

Originally Posted by Daniel_LaFleur

In his application, the wheels are purposely not in their "normal" orientation.

"normal" as specified only refers to vertical orientation, not which way it's facing.

[Ziaholic]

I do not believe that they meant "normal" when they say "normal".

I beleive that they are using the word "normal" to mean perpendicular to the floor. As long as the rotational axis is parallel to the floor, then the wheel is being used in it's "normal" position.

[Daniel_LaFleur]

Originally Posted by Ziaholic

I do not believe that they meant "normal" when they say "normal".

I beleive that they are using the word "normal" to mean perpendicular to the floor. As long as the rotational axis is parallel to the floor, then the wheel is being used in it's "normal" position.

So if you made omni wheels out of these kit wheels that would be "normal" (since the use would be used as designed)?

**note: I'm not suggesting anyone make omni wheels this year**