Weight Issues

[Solace]

Originally Posted by AdamL118

Really? Which motors and reduction included in the kit would work best for this addition? Is it worth the trouble if we hope to stay light?

hmm. lets see, if i remember correctly one of our neighboring teams (173) threw the chips onto their drive train (which used the drills) at the last second to help them turn better. I'm not sure exactly what reduction they used, though I'm pretty sure that they ran the chips at in and around 30% voltage. that being said, their high speed was about 12 ft/sec - since you probably won't be going quite that fast, you would need a bigger reduction then they had in order to get the same efficiency (remember, 30% voltage is not the same as 30% power. If you want details on how they did it i suggest you send a pm over to Joel J. the period is part of the name, not the sentence)

you would have to buy some different sprockets as the ones in the kit probably won't work. i do remember seeing this robot which has the chips tied into the drills. you could send an email over to whoever posted that pic if you needed more info on how they did that.

its always worth it to give yourself more power. believe it or not, it actually takes less battery power if you have more motors. battery power drains the fastest when you are completely stalling out a motor. if you have more motors, you have more power, and are therefore much more likely to simply spin your wheels instead of stalling. you will turn faster, go faster, trip breakers less, and all in all be more manueverable and versatile if you throw in another set of motors. the the 2 or 3 pounds that you pick up by adding them is paid back tenfold by the increase in power. remeber, lightness only matters because acceleration = force/mass. if you increase the force a lot and increase the mass a little, you're still better off than where you started.

[Matt Adams]

Originally Posted by Solace

its always worth it to give yourself more power. believe it or not, it actually takes less battery power if you have more motors. battery power drains the fastest when you are completely stalling out a motor. if you have more motors, you have more power, and are therefore much more likely to simply spin your wheels instead of stalling. you will turn faster, go faster, trip breakers less, and all in all be more manueverable and versatile if you throw in another set of motors. the the 2 or 3 pounds that you pick up by adding them is paid back tenfold by the increase in power. remeber, lightness only matters because acceleration = force/mass. if you increase the force a lot and increase the mass a little, you're still better off than where you started.

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

[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.

[sanddrag]

Originally Posted by Solace

believe it or not, it actually takes less battery power if you have more motors.

I believe it. We ran our QuardaMax G2 off a power supply with just the Chias and it drew like 3 amps no load and then we ran it with both the Chias and the drills and it ran at like 2 amps no load. And then squeeze a tube of grease in there and you'll harldy be pulling any current at all j/k Anyway, I'm sure the more motors - less current relationship depends on the motors involved and is only true up until a point.

For a low weight robot, the cool thing about that is that you can pile on all the extra junk you want later (lights, horns, hampster wheels, random blocks of lead, etc.) because you'll have the extra weight to do it.

Our rookie year, our robot was like 80 lbs and we added a 20 lb bumper. Solid iron bar. Worked very well. All we had was a simple drill motor drivetrain and one arm. We still view it as a very effective robot that was well designed and played the game well.

[tenfour]

I would say that you should look at your weights again. I think that your numbers sounds low for accomplishing all those goals. But not knowing what systems you use, I have no idea.

I think thatits important to use your weight limit as much as possible for good systems. If you are still under, make huge push bars. If you ever play us, you will need them. J/K

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[Aignam]

Originally Posted by sanddrag

Our rookie year, our robot was like 80 lbs and we added a 20 lb bumper. Solid iron bar. Worked very well. All we had was a simple drill motor drivetrain and one arm. We still view it as a very effective robot that was well designed and played the game well.

1/4 inch Steel Diamond-Plate is perrrty.

[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

[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.