Crazy robot idea for this year 2

[pandamonium]

A giant Helium balloon would off set the weight. Is that legal?

[Tristan Lall]

Originally Posted by pandamonium

A giant Helium balloon would off set the weight. Is that legal?

No it wouldn't. It would add both weight and buoyancy. The specification restricts robots on the basis of weight only.

The helium itself would be legal, unless in a hazardous state.

[EricH]

Originally Posted by pandamonium

A giant Helium balloon would off set the weight. Is that legal?

Can you fit it in the maximum size?

For something as heavy as a typical FRC robot, the required helium-carrying device will most likely have a hard time fitting in the field, if not the venue. Trust me on this. For something like a 18" sphere, with bumpers and battery, you could probably fit said helium-carrying device into the field if you didn't max-weight the robot. However, maneuverability would be highly limited due to rules about leaving the field boundary.

[Jared Russell]

Under normal atmospheric conditions, helium has a lifting ability of 1 gram per liter*. The maximum volume of your robot is 28x38x60. Let's pretend you fill that entire volume with helium (impossible, since you would need to lose some volume for the electronics, battery, bumpers, etc.)

28" x 38" x 60" x 1 gram/liter = 2.3 pounds of lifting capability. Not even enough for the cRIO itself.

* http://science.howstuffworks.com/helium2.htm

[EricH]

Originally Posted by Jared341

Under normal atmospheric conditions, helium has a lifting ability of 1 gram per liter*. The maximum volume of your robot is 28x38x60. Let's pretend you fill that entire volume with helium (impossible, since you would need to lose some volume for the electronics, battery, bumpers, etc.)

28" x 38" x 60" x 1 gram/liter = 2.3 pounds of lifting capability. Not even enough for the cRIO itself.

It gets better. You also have to have something to hold the helium. However, you could possibly get better lift by pressurizing the helium, allowing more liters to be added... which opens up its own set of problems, including the fact that helium escapes from containers very easily if there are any holes at all.

[JesseK]

The design also assumes that the life of the battery can handle the required current that it will take to lift ~25lbs off the ground. This includes the electronics, battery, motors, and "bumpers".

There's a reason Quadrotors became more popular among hobbyists after LiPo batteries became mainstream.

Each year I've tried to figure out how to incorporate a quadrotor into the game. Alas, it hasn't been pragmatic enough for 4 years. Maybe next year .

[Jon Stratis]

Originally Posted by EricH

It gets better. You also have to have something to hold the helium. However, you could possibly get better lift by pressurizing the helium, allowing more liters to be added... which opens up its own set of problems, including the fact that helium escapes from containers very easily if there are any holes at all.

Helium balloons float because helium weighs less than air. Shoving more helium molecules into the same volume won't increase lift, it'll actually decrease it! Imagine you have two 1-liter bottles of soda. They each weigh a certain amount. Now I hand you a 1-litter bottle that's been insanely pressurized and actually contains 2 liters of soda - which is heavier? The pressurized bottle weighs the same (discounting the container weight) as the two unpressurized bottles!

[EricH]

Of course, I didn't specify how much extra you pressurize it. The kind of pressures I'm used to dealing with for air/helium, you can't measure them in PSI unless you really like small decimals.

I'd also note that at least one maker of the size of helium balloons that can possibly lift an FRC robot does specify that they be pressurized, and goes to great lengths to have the balloons maintain that pressure. This is partially because said balloons need to maintain a given shape, granted--but you have to wonder if it doesn't give a tad bit of extra lift.

(Then again, these helium balloons can weigh several hundred pounds empty.)

[JamesCH95]

A perfect battery can support around 60A draw for the whole match, at around 11.5 volts. Lets be generous and say you only want a few moments of flying and the battery can support 150A at around 10.5V. This is 1575 Watts, which should be able to lift around 16-17lbs.

I do not believe that it is possible to lift all of the required hardware (battery (13lbs), cRIO (1.4-2lbs), cRIO modules, power board (1.6lbs), digital sidecar (0.25lbs), main breaker, bumpers, motors, radio (0.5lbs) etc) with the battery's available power. This is even without accounting for losses such as resistance in wiring and motor inefficiencies. In fact, that 1575W of theoretically available electrical power is probably around 1200W if you use RS775-18s at peak efficiency (78%). Voltage at the motors will be lower than 10.5V, so ding some more power...

I think it's safe to say that the battery cannot output enough power to lift the absolute minimum FRC legal robot.

[remulasce]

I'd also note that at least one maker of the size of helium balloons that can possibly lift an FRC robot does specify that they be pressurized, and goes to great lengths to have the balloons maintain that pressure. This is partially because said balloons need to maintain a given shape, granted--but you have to wonder if it doesn't give a tad bit of extra lift.

This is still not how buoyancy works. The idea is to get the least weight to take up the most volume. The volume determines how much lift is produced. The lifting element is there to maintain volume with as little weight as possible. Because pressure of a gas is not related to the molecular weight of that gas, elements with very low molecular weights are used to match the outside atmospheric pressure, so the volume of the balloon is maintained. Your manufacturers suggest inflating beyond that pressure to give additional rigidity and in case of leaks, but once the balloon volume is full, all you're doing is putting more weight into the balloon.

[pfreivald]

A leaping robot that jumps forward over the fender and then clambers up the baskets -- blocking all four of them with a shape change -- is both technically feasible and within the rules.

We thought of it day one, then said, 'naah.'

[maxweberh]

You could have always put a fan, on the robot, went over the bump/bridge. Sat in your alley, and aim at the top 3 hoops. I think that is a smart plan for defense.

But once again, I would love a flying robot.

[Akash Rastogi]

Originally Posted by maxweberh

You could have always put a fan, on the robot, went over the bump/bridge. Sat in your alley, and aim at the top 3 hoops. I think that is a smart plan for defense.

But once again, I would love a flying robot.

Don't encourage him Max

[Siri]

Originally Posted by CalTran

Well, I think that the things that make this illegal to be:


^Even if you were able to get flying, you're still restricted to an air ceiling ~10" above the ground.

That's where the bumper zone is located, but it only matters with regard to R29 (in fact, it's only ever mentioned in these two rules).

[R29] Bumpers must be located entirely within the Bumper Zone when the Robot is standing normally on a flat floor.

Otherwise no one would be able to wheelie onto the bridge, lift themselves across the barrier, etc.

It seems the GDC also has chosen not to answer the question of whether a circular (or spherical) robot has no exterior vertices or infinite ones, so you might not need bumpers at all! ([R27]: "Robots are required to use Bumpers to protect all exterior vertices of the Frame Perimeter".)

Originally Posted by remulasce

In addition, no part of your robot may extend more than 60" off the ground- wait. Only when in contact with the other alliance's carpet. So you're good on that front.

True, all robots are limited to 60" while in contact with the "carpet and/or Key on their Alliance Station end of the Court" [G20].
...However, "Otherwise, Robots are limited to 84 in tall" [also G20].
...However, "The vertical measurement is always in relation to the Robot." [Q&A, G20]. Those tricky GDCers

So as long as your flying robot is not over 84" tall and not over 60" tall when placed on the Court before the match [G01]--with respect to itself--it should pass G20 and G01. (G01 is not clear about cases in which the robot is never actually placed on the Court, i.e. it floats.)


Now the safety thing, that's an issue. Field personnel have enough problems without a flying ball of helium filled with a battery+cRio*+router+/-bumpers flying at their heads. Yikes!


*[R52] Robots must be controlled via one programmable National Instruments cRIO (part # cRIO-FRC or cRIO-FRCII), with image version FRC_2012_v43. Other controllers shall not be used.