375 LBS??

[dodar]

Originally Posted by thisOrrthat

We used the golden ratio to determine our length and width. Still keeping a perimeter of about 110".

What is the ratio?

*edit* Posters below answered it.

[Dr Theta]

Well if they are referring to phi I think it would be more like 34x21

[smistthegreat]

Originally Posted by dodar

What is the ratio? 3:2? 36" x 24"?

If I'm not mistaken, the golden ratio is 1.618:1

Edit: Got beat to it, 34/21 is 1.619 with sounds just about perfect.

[Chris is me]

Not to take anything away from your great looking drivetrain, but pushing 375 pounds of mass sitting in a chair is not the equivalent of having 375 pounds of pushing force. The coefficient of friction between the chair legs and carpet is certainly less than 1.0, so the actual pushing force would be less than that.

That said, beautiful drivetrain.

[theawesome1730]

Originally Posted by Chris is me

Not to take anything away from your great looking drivetrain, but pushing 375 pounds of mass sitting in a chair is not the equivalent of having 375 pounds of pushing force. The coefficient of friction between the chair legs and carpet is certainly less than 1.0, so the actual pushing force would be less than that.

That said, beautiful drivetrain.

True, but a robot on wheels (while unpowered of course and parallel to our own wheels) should theoretically have a lower coefficient of friction than the chair? Please correct me if I'm wrong.

[Steven Donow]

Originally Posted by theawesome1730

True, but a robot on wheels (while unpowered of course and parallel to our own wheels) should theoretically have a lower coefficient of friction than the chair? Please correct me if I'm wrong.

Not necessarily. You appear to be using the AM HiGrip Wheel (if I'm not mistaken), and assuming your carpet is standard FRC carpet, the CoF is listed as 1.067. I'd guarantee that roller chair wheels have significantly less grip than that.

[theawesome1730]

Originally Posted by stevend1994

Not necessarily. You appear to be using the AM HiGrip Wheel (if I'm not mistaken), and assuming your carpet is standard FRC carpet, the CoF is listed as 1.067. I'd guarantee that roller chair wheels have significantly less grip than that.

Thanks for clarifying that for me. Either way, it still has a huge pushing force. Not shown in the video is me sitting on the carpet (which is FRC carpet) and having the robot push me. I only weigh about 150 lbs, but I would assume the coefficient of friction for jeans on carpet is much higher than chair feet

[darkember]

Im scared, i dont think our team wants to be pushed around

[propionate]

Originally Posted by theawesome1730

Thanks for clarifying that for me. Either way, it still has a huge pushing force. Not shown in the video is me sitting on the carpet (which is FRC carpet) and having the robot push me. I only weigh about 150 lbs, but I would assume the coefficient of friction for jeans on carpet is much higher than chair feet

Going through a few different sources on the internet, it looks like the CoF between aluminum and carpet is somewhere between .3 and .7 (loose average). Let's say .5, and that would give you a pushing force of about 180 pounds. Still very formidable. Welcome to any corrections on the CoF I estimated.

[TheCrayButton]

Nice shooter! Like it. Seems very accurate too! Can't wait to see it at Kansas City!

[Cory]

Pushing force is a zero sum game. Unless you've discovered some super material with a CoF greater than 1.3 you can exert no more force than any other robot that weighs the same amount.

[propionate]

Originally Posted by Cory

Pushing force is a zero sum game. Unless you've discovered some super material with a CoF greater than 1.3 you can exert no more force than any other robot that weighs the same amount.

What is the source of the 1.3 number?

[mman1506]

We were able to drag two people across the floor with a two sim kitbot without a issue. Better step up your game . Beautiful chassis BTW

[Cory]

Originally Posted by propionate

What is the source of the 1.3 number?

It's commonly accepted that the "best" tread materials used in FRC give a static CoF of around 1.3.