More Wheels?

[funstuff]

Originally Posted by lynca

In 2002, 624 made a robot with a 5th high traction wheel in the middle of the robot for pushing/shoving during the game. I don't have a picture of the robot but it was a beast. If anyone has a picture I would love to see that robot again!

I'm not sure that the 5th wheel will help you since you would be dividing your normal force by 5 wheels instead of 4 wheels.

A 5th wheel helps with traction when you have carpet but not with FRP !

http://cryptoniterobotics.org/images/2002.jpg

^ the 2002 robot, minus side panels and bumpers. And it was the most beastly robot FRC has seen. It pulled a small car (or so I've heard). Last that I have heard, it is still in (somewhat) working order.

For Andy's reminiscing pleasure: http://cryptoniterobotics.org/team/robots/

-Kat

[bigbeezy]

i meant to get a closer look at SPAM's robot (180) at Florida but I believe they have, in addition to their normal drive and a fan, a set of wheels possitioned perpendicular to the others and they would pneumatically lower the wheels. these were mainly for a semi-swerve affect, but i suppose could be used as a break. I'm sorry i dont have a better explaination i only saw it from the stands.

[keehun]

Is it possible (and legal) that you make pneumatics strong enough that you mount a wheel perpendicular to other wheels, then when you want to brake, you gently lift the robot using that wheel, tilting it just ever so slightly, and applying that downward pressure and braking faster?

Imagine sliding your hand over the desk, and the sliding your hand over the desk with a lot of downwards pushing..?

You can only use up to 78 rover wheels in contact with the ground. No more.

[artdutra04]

Originally Posted by keehun

Is it possible (and legal) that you make pneumatics strong enough that you mount a wheel perpendicular to other wheels, then when you want to brake, you gently lift the robot using that wheel, tilting it just ever so slightly, and applying that downward pressure and braking faster?

Imagine sliding your hand over the desk, and the sliding your hand over the desk with a lot of downwards pushing..?

If you think about it, that will only work as long as the robot mass is accelerating upwards.

As soon as the robot stops accelerating upwards (and begins to coast), the force pushing down on the wheels will return to its pre-acceleration value. But a robot cannot possibly keep moving upward forever, or even offset a partial amount of its downward acceleration due to gravity.

Therefore, the robot must begin to slow down its upward velocity, experiencing negative acceleration. During this period, the robot will actually have less normal force pushing down on the wheels, meaning less pushing power.

So yes, you can do this; you'd just get a very limited period of increased traction followed by a limited period of decreased traction.

Think of if like a roller coaster. When you go through a dip, you feel positive gee forces, and when you go over a peak you feel negative forces.

[R.C.]

Originally Posted by CraigHickman

You can only use up to 78 rover wheels in contact with the ground. No more.

Thatz a bit harsh craig we wanted to use like 79.

[artdutra04]

Originally Posted by rc_cola1323

Thatz a bit harsh craig we wanted to use like 79.

Doing some napkin calculations (read: no optimization), 112 is the hard limit for number of wheels you can have contacting the floor.

[David Doerr]

Originally Posted by artdutra04

Doing some napkin calculations (read: no optimization), 112 is the hard limit for number of wheels you can have contacting the floor.

Our Software & Controls group has done very precise calculations and found that, at least for our machine, the limit is 112.67 wheels.

[Molten]

Originally Posted by DaveD

Our Software & Controls group has done very precise calculations and found that, at least for our machine, the limit is 112.67 wheels.

That's what you get for having your software guys do hardware calculations.

[lynca]

Originally Posted by funstuff

http://cryptoniterobotics.org/images/2002.jpg

^ the 2002 robot, minus side panels and bumpers. And it was the most beastly robot FRC has seen. It pulled a small car (or so I've heard). Last that I have heard, it is still in (somewhat) working order.

For Andy's reminiscing pleasure: http://cryptoniterobotics.org/team/robots/

-Kat

Thanks for the trip down memory lane !
I'm glad to see 624 won the regional at Bayou !

Go CRyptonite !

[Daniel_LaFleur]

Originally Posted by funstuff

http://cryptoniterobotics.org/images/2002.jpg

Wow ... Drill motors, No Kitbot Chassis, and the revolving light (How I loved that light).

[mjazzka]

Originally Posted by lynca

In 2002, 624 made a robot with a 5th high traction wheel in the middle of the robot for pushing/shoving during the game. I don't have a picture of the robot but it was a beast. If anyone has a picture I would love to see that robot again!

I'm not sure that the 5th wheel will help you since you would be dividing your normal force by 5 wheels instead of 4 wheels.

A 5th wheel helps with traction when you have carpet but not with FRP !

Here is a picture of our robot from that year for ya! We just call it the tank bot, and it just sits there doing nothing. And btw, that 5th wheel is the butt of many, many jokes lol. The 5th wheel is in the center of the robot, kind of hidden but nevertheless there.

http://picasaweb.google.com/RazorTip...3129 88959794

[reversed_rocker]

adding more wheels may increase your surface area, but it spreads out your weight. The net gain in traction: exactly 0. Even extra powered wheels dont help, assuming you keep the amount of power is the same. the only reason why 4 powered wheels could be better than two powered wheels is 1: more motors to power the 4 wheels, therefore more power or 2: if some of your wheels dont have traction, it's possible to pull yourself out of a bind with the wheels that do. It's a common misconception that more wheels = more traction, thats why you see so many 4 wheel drive cars in the ditch during wisconsin winters

[funstuff]

Originally Posted by mjazzka

Here is a picture of our robot from that year for ya! We just call it the tank bot, and it just sits there doing nothing. And btw, that 5th wheel is the butt of many, many jokes lol. The 5th wheel is in the center of the robot, kind of hidden but nevertheless there.

http://picasaweb.google.com/RazorTip...3129 88959794

Thanks, Michael. I only wish we had more than one picture of Tankbot from that year.

We have used it in demonstrations at least through 2007.

[mjazzka]

LOL i did NOT see you had already posted a picture, sorry about that

And I will work on getting more pictures of that robot for you, it is still lying around SOMEwhere...