How Loud is Too Loud? (Cal Games)

[=Martin=Taylor=]

Team 100 has been spending an enormous amount of time preparing our robot for the California Robot Games.

We have rebuilt our ball-lifter, completely redesigned our 3-pt shooter, tuned up the drive train, and rebuilt our hopper.

But we have a problem. Due to a lack of sophisticated tools we were never able to balance our shooter. When spun at top speed it releases the most deafening racket I have ever heard on a FIRST robot. It quite literally sounds like a jackhammer or possibly even a machine gun. .

We don't know what causes this problem. The best hypothesis seems to be that at a certain speed the shooter's chain begins to vibrate making noise.

In fact, if it weren’t for the noise it wouldn't seem that anything was wrong. It seems to run fine, nothing breaks. We have also encased the entire shooter mechanism in fine-mesh chicken wire so that if anything did go wrong it probably wouldn't go flying.

My question: is our robot safe enough to compete? It sounds dangerous but it really isn't.

[sanddrag]

Well, it is good in one way I guess. It gives more for the announcers to comment on.

[eugenebrooks]

Originally Posted by Hachiban VIII

But we have a problem. Due to a lack of sophisticated tools we were never able to balance our shooter. When spun at top speed it releases the most deafening racket I have ever heard on a FIRST robot. It quite literally sounds like a jackhammer or possibly even a machine gun. .

We don't know what causes this problem. The best hypothesis seems to be that at a certain speed the shooter's chain begins to vibrate making noise.

From your description, it seems that a mechanical reasonance is being excited in your chain at a specific speed. In general, chains are meant for slow speed operation, where such reasonances do not occur. If you have any flexibility in the mounting, shorten the chain as much as you can.

Safety will be the most important concern of the technical inspectors for the Cal Games, as it always is at a FIRST competition. If you are concerned about whether a mechanism on your robot is safe (making sounds like a jackhammer or machine gun are not great indicators) you can be sure that technical inspectors will be concerned as well. It can't be judged, however, until it is seen (and heard) at the Cal Games.

See you there...
Eugene Brooks

[Robo_Coyote]

our team had a problem like this at last years Davis Regional except along with making noise we kept throwing our chain off too. We fixed the problem by going to a belt drive and never had a problem after. Chains are just to troublesome when the are long. If you need to connect something long use a belt!!!!! hope this helps

[AdamHeard]

I'm sorry,
but I believe our robot was the loudest... Even at 20% of the max speed the refs constatly said it was too loud and annoying.


Too bad I won't be at the cal games to truly see which team has the loudest robot ever.

I really wish I could check yours out because I can't even imagine a robot being more obnoxious...

[dlavery]

Originally Posted by cromat44

I'm sorry,
but I believe our robot was the loudest... Even at 20% of the max speed the refs constatly said it was too loud and annoying.


Too bad I won't be at the cal games to truly see which team has the loudest robot ever.

I really wish I could check yours out because I can't even imagine a robot being more obnoxious...

heh heh - I smell a new award in the making: "Most Obnoxious Robot"!!!

I think that Team 116 would certainly have been a contender with their robot from 2003. That year we used treads, with large tread "bumps" that interacted with the sprockets on the interior of the treads. A series of 3-inch long 1/4-20 spacer bolts held the side plates of our drive modules in place. The spacer bolts just happened to be positioned so they just barely cleared the bumps on the treads as the treads were running. So we took a set of 2-1/2 inch lengths of copper plumbing pipe, and put one loosely over each spacer bolt. The pieces of pipe were thus positioned so that every time one of the tread bumps hit it, the pipe was slammed into the spacer bolt with a nice loud metal-on-metal "clang!" With two treads running at about 9 feet per second over 12 of these pipe-covered bolts, we were pounding out about 2600 very loud impacts per second. We never actually stuck a decibel meter up against the thing to know exactly how loud it was. But it was loud enough that when it was running in the pits at the Richmond Regional, you could hear it out on the playing field over the sound of the amplified music from the DJ!

-dave

[KenWittlief]

Originally Posted by Hachiban VIII

My question: is our robot safe enough to compete? It sounds dangerous but it really isn't.

Everyone knows that electronics are pumped full of smoke. When the smoke leaks out electronics stop working.

Most people dont realize that mechanical parts are pumped full of noise. This is why they are made on very noisy machines.

Ideally the noise will be let out of the parts a little bit at a time. The reason is, once all the noise has leaked out, the parts will stop working. Sometimes the noise leaks out all at once: BANG! and then its all over.

Sometimes you can put a little bit of noise back into a mechanical part, either by screaming at it, or wacking it with your fist or a hammer. But usually it has to go back to the machine shop to be pumped full of noise again to work properly.

Having said all this, I dont think your robot is long for this world, if you have a serious noise leak! Something is scraping, ginding, or banging against something else, or your unbalanced shooter is vibrating itself to death. I would be concerned about metal fatigue, and something breaking.

[eugenebrooks]

Originally Posted by dlavery

heh heh - I smell a new award in the making: "Most Obnoxious Robot"!!!
-dave

Note to self, another item for the safety checklist. Robot not
to exceed the threshold of pain, nominally 130 db, at a distance
of 5 feet. We'll keep the music down so we can hear ya.

[Richard Wallace]

Originally Posted by KenWittlief

Everyone knows that electronic are pumped full of smoke. When the smoke leaks out electronics stop working.

Most people dont realize that mechanical parts are pumped full of noise. This is why they are made on very noisy machines. ...

By this logic, electronics should be made in smokehouses, like bacon or country hams.

[eugenebrooks]

Originally Posted by Richard

By this logic, electronics should be made in smokehouses, like bacon or country hams.

The smoke gets into the electronics with you solder the connections.

Eugene

[Richard Wallace]

Originally Posted by eugenebrooks

The smoke gets into the electronics with you solder the connections.

So lead-free electronics should contain more smoke, since they are soldered at higher temperatures, right?

[AdamHeard]

Is it also safe to assume that batteris only have a certain amount of sparks, and after that they don't work anymore?

[Greg Marra]

To get back to the original question of "How Loud is Too Loud?".

This loud:
|----------------------|*


Just use common sense. If it sounds like something is going to break, try to find where the problem is and correct it before it is an issue.

*(not to scale)

[yodameister]

Originally Posted by dlavery

heh heh - I smell a new award in the making: "Most Obnoxious Robot"!!!

-dave

I would definitely throw our robot the MegaMaid into this category. When we fired up our intake rollers you could hear it from across the arena.Here is her picture.

[artdutra04]

To use some Jeff Foxworthy logic...

When the police show up for night-time noise violation laws even though it's the middle of the day,
you might have a shooter that's too loud.

When the sound waves from your robot can register on the Richter scale,
you might have a shooter that's too loud.

When your drive team has bleeding ears after a match,
you might have a shooter that's too loud.

When the CIA shows up to confiscate your robot to use in Iraq to "smoke" terrorists out of buildings,
you might have a shooter that's too loud.

When a deaf spectator shows up and tells you to keep the noise down,
you might have a shooter that's too loud.


For your actual robot, use your best judgement. Try to see if anything can be fixed, tightened, etc. You also might want to try lubing the moving joints, and then run it for several minutes to break it in.