Weight Issues

[Nick R.]

if you realy intend on going to the center to stop other robots from hanging you ned to be able to push them off because a robot with a climbing mechanism will way at least 90-100lbs so you need to be able to counter that.
Last year, in our rookie year, we were at 81lbs, and last year pushing was a big thing.. which we failed at... so this year we're aiming at 100 pounds.. nice round figure.. should be good

[Solace]

Originally Posted by Matt Adams

With all due respect.. there's a lot of things here that aren't quite correct.

More motors will use more power, which will drain your battery faster if all your motors are stalling out.

When your motors aren't at stall, assuming that you're running them optimally pulling equal current at 12 volts... you'll be pulling either (for example) 30 amps from 2 motors or 15 amps from 4 motors... since power is a function of current and voltage, there will be a more or less constant power pull. I could argue that due to efficiency, more motors will always require more power draw... but that's besides the point. More motors will mean draining your battery at about the same rate when you're not stalling your motors, and when you're in a pushing match, they'll drain faster- but it's usually well worth it since the matches are so short, and the batteries can be recharged!

It should be noted that the Chips weigh in at around 3 lbs each... chain is a fraction of a pound per foot, and sprockets weigh a fraction of a pound each. You also need to mount the motors, including fasteners, brackets, wire etc... the weight addition of two motors to a drive train will most likely be closer to 8-10 lbs than 2 or 3.

However, I do agree with Jake that more motors is a good idea if you've got weight. I'd strongly suggest that you look into it! I've believe it's well worth it if you have the weight to spare. You can ask me for help on combining motors if you'd like, or I know that JVN would love to show you his cool white paper that could help you do it too.

Good luck!

Matt

... and it is once again proven that Jake isn't nearly as smart as he thinks he is.

while I don't think it would be as heavy as 10 pounds, Matt is correct when he says that it will be heavier then my original assertion.

whatever you do, don't try to outdo yourself (i.e. this would not be a good time to attempt to build a technocat transmission). it is more important that the things you do have on the robot work well than it is that they do everything.

[KenWittlief]

if you are able to drive up to a wall, and spin your tires on a carpet, then adding more motors to your drivetrain wont give you anything but more complexity and greater probability that something will fail or break

the more parts you add, the lower your machines reliability.

once you are able to spin your wheels, more horsepower will only let you spin them faster - and the coeffecient of kinetic friction has nothing to do with how fast the tires are spinning - once they start to spin the force they produce is the same, no matter how fast they spin.

[Jeffel]

to the original post?- all that matters is that your under the 130lbs. like some 1 said before... y stop at 100?

[Rhs953]

Its gonna go up the stairs no matter what the weight is (lets be practical here ). Just be sure that your center of gravity is low. That way when you do climb up the stairs the robot wont tip over.

Just a FYI, our robot is 90 lbs without an arm and it gets up the stair just fine.

Also when you use metal you frame will probably be .2 times heavier so no matter what you do it will be heavier.