Magnets allowed?¿?
 

Is there any rule against using a powerful enough magnet to stick to the pull-up bar? We would be able to turn it on and off, obviously, so it doesn't go around attached to the other robots. :D

Thanks,
Team 992

Re: Magnets?
 

An electormagnet would not stay "on" or attached once the power was shut off. Your robot must be able to stay even when the power is shut off or you do not get the points for it.

On the other hand, you could use an electromagnet coupled with a passive latch to keep you held on the bar once power was shut off.

I looked in the manual and because electormagnets are not included in the KOP, they would fall under the Custom Circuits requirements (meaning they would not be allowed because of rule R52).

<R52> Custom Circuits may not:
• Directly affect any output devices on the robot, such as by providing power directly to a motor,
supplying a PWM signal to a speed controller or supplying a control signal to a relay module.

Please ask this question on the FIRST Q&A site and report back.

Note:there is nothing on the Q&A site so far that has the word magnet in it.

If anyone finds something to the contrary, please post it.

Re: Magnets?
 

thanx

Re: Magnets?
 

What about regular magnets that you can pick up in a store (for w/e you wanted to use it for)? Just wondering, since that wouldn't be an electromagnet.

Re: Magnets allowed?¿?
 

The word magnet only appears once in the robot section of the manual (5) and not at all on the Q&A site. That reference is talking about how the current sensor works.

According to the Parts Use Flowchart, if you can get it in one of the ok'd places then it's legal.

Re: Magnets allowed?¿?
 

Electromagnets are not allowed under the rules. If you follow the flow chart there is a section on electronics where it askes the question "Is the part a motor, solenoid, pump, or other actuator?" Since the answer is Yes you cannot use it. An electromagnet is by definition a solenoid, i.e. a coil of wire, wound around a form, that induces a manetic field by the introduction of electricity, to attract another metalic object. Sorry.

Re: Magnets allowed?¿?
 

part of the other trouble its the magnetic force could also possibly interfier with radio of other robots, or pull steel parts off if it was powerful enought to hold the robot... 100 posts! oh yeah!

Re: Magnets allowed?¿?
 

I don't know. It seems the spirit of that rule is an electromechanical device - an electromagnet is not that, right?, only half of that. And yes, you are certainly right, it is a solenoid by defn, but the spirit of that rule..... I mean, one could argue that any loop of wire is a solenoid, but we know the spirit of the rule. Would be rather interesting to see an electromagnet that could lift a robot when attached to a round bar and be able to spend some time on the bar with no battery power when the match is over. And to add to that, i wonder if magnet wire is allowed - i suppose so, but you have to keep to the correct size.... I highly doubt anyone could produce such a device given the rules, but gee, i'd be curious to see a prototype even if it isn't allowed :D

Re: Magnets allowed?¿?
 

Max,
An electromagnet would not produce interference with the radio modem in and of itself. Big coils do have this natsy habit of producing an arc at the switch when you try to remove current from the coil. That arc is capable of a lot of energy in the RF range and might be enough to disrupt the modem.
As to your closing signature, another form I heard "way back when" relates to the F104 fighter. Marines were heard to say it proved if it you put a big enough engine on it, you could get a brick to fly.

Re: Magnets?
 

It would be almost impossible to find a magnet that could hold 130 lbs. for a reaonable cost.

Of course, if you've got money to burn, it doesn't matter does it? :D

Re: Magnets?
 

You could buy 4 magnets that each hold 35 pounds though.

I seem to recall a surplus catalog showing 100pound+ magnets at reasonible prices (under 50 bucks) of course I couldn't tell you the name of the catalog , thats lost in the buzz of too many catalogs.

I hadn't thought of magnets. But they could be used to help 'find' the bar when you aretrying to hook it.

Re: Magnets?
 

Ohhh yes!!! I have a few. I have a pair of 1 1/4" neodymium disk magnets that have easily held me without a sweat.

Preferably you want NeFeB(aka neodymium or "rare earth") magnets with a second choice of SmCo. Ceramic and Alinco magnets are pretty much useless for this sort of thing.

All i can say is don't hurt yourself w/these things. Speaking from experience thye can cause some pretty bad injuries whrn they stick to stuff they're not suffosed to.
Suppliers:
http://www.wondermagnets.com/cgi-bin...manent_Magnets
http://www.allelectronics.com/cgi-bi...370&type=store

As far as isolating them from stuff that shouldn't be too much of a problem. Just put some thin steel sheet against all the unused surfaces and isolate that from the rest of the robot with some Aluminum or Plexi. I have never noticed a problem with RF interference either.

If you want an idea of the strength of neo magnets then bust open an old hardrive and it will contain some very small ones, which actuate the head assembly. (but not too old. If its a 3.5" then it will have them. any older and it may or may not.)

Instead of using them to attach to the bar, I see them as having greater applications moving goals. Simple: Powerful magnet + pnumatic detacher = easy goal dragger. This solves the problem of having nothing to grab onto. It also solves the problem or precisely aligning a mechanism w/ the goal.

Re: Magnets allowed?¿?
 

The problem with magnets is not that they can interfere with the radio modems, but that a changing magnetic field will create a current flow through wire I don't know how much current this would induce, but it could possibly be enough to mess with the pwm signals or other electronics of other robots. You may have to be careful to avoid this if you use a powerful magnet.

I found this website which has one magnet with 115 lbs. of holding force while weighing less than a pound for about $130. With a few of these, the hard part about hanging on the bar would be finding a way to release the robot at the end of the match.

Re: Magnets allowed?¿?
 

magnets change the way that electrons move so that could possibly interfere with the radio signals as previosuly mentioned. It could also interfere with the function of other robots assuming that the magnet was that powerful...some thoughts to consider...

Re: Magnets allowed?¿?
 

Even with VERY powerful magnets, it would be VERY difficult to induce enough voltage in anything to cause interference. It would take ALOT of gauss. and remember 1/x^2 rule. Anybody care to work out some Emag? Maxwell's equations Mmmmm...

Re: Magnets allowed?¿?
 

I'm not sure about the exact amount induced, but I did have problems with using my cell phone when i got within about 6 in. to a foot of a magnet that came from an old hard drive. It did not cause problems with interference, but caused my phone to reset itself.

You probably wouldn't interfere with another robot from several feet away, but depending on the location of the magnet, it might cause problems when the robots are very close to each other.

Re: Magnets?
 

Sorry, but the goals are made of aluminum and aluminum will not be attracted to the magnet.

-Dave

Re: Magnets allowed?¿?
 

Neodymium magnets are easy and cheap to come by so
price is not a factor. These magnets are dangerous and care should be used handling them. Here are the reasons:
a) They shatter easily. The force of two magnets attaching to each other is enough to break them and cause shrapenel to fly.
b) They can seriously hurt someone. Companies warn people about the power of the little magnets. Bigger ones could accidentally break bones unless care is taken.
c) Once they are attached to something they are really hard to separate. I am not really sure if this would be an safety issue but you would have to be design the robot with some way to easily deattach the magnet.
d) Aparently they can affect pacemakers and other medical devices.
e) They can ignite accidently and burn very fast like magnesium does.
More Safety Tips Wow
Even More Tips
The Japanese have used these magnets with a lot of success in their sumo robots. They actually fought with their robots upside down.
Here is another link to more information:
Another supplier/Faq on magnets

Re: Magnets?
 

Are you sure? I thought they were steel diamond plate on the side. I will have to check this later.

Re: Magnets allowed?¿?
 

Add keep them away from computers. I just got one too close to my monitor, and ouch! I'm not talking about magnetizing the shadow mask/apature grill and distorting the colors either. The magnet was soo strong that it bent and stretched a few hunderd of the shadow mask wires!! I now have irreparable black lines across about the middle quarter of my screen. I can hardly see what i am typing. Ooops!!! I guess it's my own dumb fault. At least this isn't my good monitor. (or i wouldn't have been messing w/magnets.) (switches monitors)

----------edit------------
Haha. If i hit the monitor hard enough, the bent wires oscillate and i can see the oscillations almost as if i were lookign at an oscilliscope because of the scanning of monitor highlighting them.

O joy, i also just realized its now probably emitting low levels of X-rays as the electron beam bounces off the bent shadow mask wires at undezired angles. (emits X-rays, which are normally emitted backward and adsorbed by the lead infused glass in the back.)

Re: Magnets allowed?¿?
 

If you ever get a hold of a black and white television have fun with the magnets. They do no damage the cvt/phospher screen and the magnets actually distort the screen. It is pretty cool.

Re: Magnets allowed?¿?
 

And once you finally get bored of that, take it apart and rip out the beefy flyback transformer that most old B/W TVs have and build yourself a tazer sparky thingy. There are are actually alot of useful components in old TVs.

Re: Magnets allowed?¿?
 

Maybe a theory would be not to use the magnet to hold up the robot, but maybe help guide an arm with a latchin device right to the pole:

Heres an example:

Robot "FRED" has a slightly flimsly arm that can reach the height of the bar with a latch that will grip onto the bar once it is close enough to it.

The drive runs the robot under the bar and the magnet on top of the slightly flimsy arm attracts to bar with little effor from the driver to position the bot. The robot then lowers its latch which is now a perfect distance from the bar because of the magnet.

Maybe that has some use?


Other wise, the weight to power ratio of a magnet to lift 130 pounds would not be too efficient.


Gabe Goldman

Re: Magnets allowed?¿?
 

With typical magnets yes, with neo magnets this iisn't a prob at all. A 1ib neodynium magnet could probably easibly lift 2 robots.

Re: Magnets allowed?¿?
 

I stand corrected, havent heard of neo magnets. But if a 1 lb mass of neo magnet can hold that much force, it's field will most likely effect robot controllers or maybe "latch magnetically" onto other robots inadvertantly.


If I were an inspector, and my metallic clipboard got stuck to your magnet while I was reviewing your bot, I would be concerned:)

Gabe Goldman

Re: Magnets allowed?¿?
 

Lol.

Re: Magnets allowed?¿?
 

James, Could you explain this in a little more detail? Exactly where did you apply the magnet and what type of monitor are you using? Are the black lines vertical or horizontal? Don't worry about additional xray, the radiation is produced when the electron beam strikes the faceplate due to the high voltage. (30-45 KV)

Re: Magnets allowed?¿?
 

Some monitors(especially those made by Sony) and a very few tvs use an array of VERY thin wires rather than a plate thing for the shadow mask. If you can see 2-4 VERY VERY thin horizontal lines acroos your screen then your screen uses wires. (the horizontal lines are support wires). Anyway, I put the magnet right up to the screen and bent/tangled/stretched the wires. There are now lots of little thin vertical line across the screen. The reason i mentioned X-rays is that since there are now gaps in the grid, it seems like electrons hittign the side of the gaps in the grid would emit X-rays at anglis in front of the screen. (i know its probably harmless amounts)

Re: Magnets allowed?¿?
 

James,
I work with a man who worked at Sony for many years and this is his opinion...
The high resolution Trinitron tube has a very fine shadow mask to match the small phosphor stripes on the front of the tube. The electrons from the three color guns pass through the slots in the shadow mask at different angles to energize the three color phosphors printed on the inside of the faceplate. The shadow mask is so fine that changes in temperature were affecting the beam landing so Sony introduced a support structure that compensated for the temperature and supported the very fine mask. Those are the two fine black lines you see running horizontally at about a third and two thirds of the screen height. The metal parts of the picture tube are affected by magnetic fields like speaker magnets and the earth's magnetic field. There is a degaussing coil built around the picture tube that generates a moving and variable intesity field, at turn on, that is supposed to erase the magnetic field taken on by the metal parts. What we feel has taken place is the magnet you applied has generated such a strong field, the degaussing coil cannot overcome it. There are coils that are used by service people that can erase this field. What we think is occuring is that the magnetic field on the shadow mask is causing the electrons to strike the black stripes between the color phosphors on the faceplate of the tube and that is what is causing the black vertical strips. If you look close, you should see the there is faint color at the very edges of the black lines. If this is the case, you need to see if you can borrow one of the service deguassing coils or take it to a TV shop and let them try to deguass it.

Re: Magnets allowed?¿?
 

Hmm sounds possible(from my limited understanding of CRTs). Its seems to me that if the shadow mask were this magnetized, the colors would be distorted. I don't have access ot a degaussing coil, and i don't feel like payign for somethign soo simple. From my understanding, a degaussing coil is nothign more than a big 60hz electromagnet that plugs into the wall. Anybody know how many turns of what radius i need to build one?

I just realized somehting about the vibrating patterns when i hit the screen. Its not the actual lines that are moving, but rather it seems they are casting phantom vibrating lines beside themselves. Also, Its hard to tell, but some of the lines do seem to have colors bordering them.

Re: Magnets allowed?¿?
 

Fun thread. Too bad that the Neodymium magnets would probably shatter if they were allowed to slam in to a bar rapidly when used as a guide. Even magnets that are tougher can have their magnetic strength reduced by shock. In the trade it's called "thumping" and is a crude way to adjust the magnetic level downward if you don't have a magnetreater (sort of a controlled degausser). Just tap it with a little hammer.

Ever see what it takes to charge up some of these magnets? Check out the 110,000 Joule charger: http://www.maginst.com/capacitive.html. I used to work at a company that made some of these same chargers (up to 20 KiloJoule). The techs called them "widow makers". You didn't want to get hold of a huge bank of capacitors charged up to 2000-3000 volts DC!

Re: Magnets allowed?¿?
 

Soo thats why all my magnets eventually get weaker: impact forces as they stick to things.


Mmm... 110,000J capacitor bank. That would do wonders for a railgun. :)

To prevent Neodymium magnets from shattering, why couldn't they we cubered by a thin plate of something stronger. Por additional impact resistance, the plate could even be dipped in that tool handle coating stuff.

Re: Magnets allowed?¿?
 

James,
On a Trinitron tube the phosphors are stripes rather than dots. So it is unpredictable as to what the outcome would really be. The best test is turn the monitor on and get something displayed. Then while it is on turn it 90 degrees. The change in orientation to the earth's mag field will change the display. If it makes the vertical lines worse then degaussing may be the answer. If it goofs up the color but doesn't change the vertical lines then you may have cashed the CRT. Ask around at school, there may be a coil in the repair shop or at the district office they may let you use for a few days. Building one is dangerous and reguires some materials you may not have access to. Good Luck!

Re: Magnets allowed?¿?
 

Shock is not the only way to reduce the field. Here's the word from Roger at Magnetic Instrumentation: "You got the term thumping of a magnet right. The thumping shock does tend to throw a certain number of particles off the magnetized orientation and then you have north polarities and south polarities negating each other and producing less energy out of the magnet. To get the maximum energy out of a magnet you want all the particles aligned in the same direction, to get less energy you need realign some of the particles “Off axis” by mechanical or temperature (typically heating) shock or by applying a reverse polarity DC or an alternating AC field." In addition, you've probably seen horeshoe magnets with a little steel plate stuck on. I haven't exactly researched the phenomenon, but this is known a "keeper" to keep the magnet from weakening. It effectively closes the loop between the North and South fields. I'll see if I can find out any more about it.

And by the way, I've heard about people using one of those big Weller-type soldering guns (the ones with the wire loop) being used as degaussers. Search on "soldering gun degausser" and you'll see. If the monitor is really big, maybe you could use one of the coils that they use to degauss battleships (yes, they do that - don't want to set off magnetic mines).

Re: Magnets allowed?¿?
 

This is actually another mentor on the Team 236 design/build team, Jim. I cannot figure out how to log in under another name using the school computer system, so I am using Jon236's profile. If this causes a problem, let Jon236 know and I will figure out how to get my own profile.

I have been watching this thread with interest and have not seen whether the original question was answered. Are magnets going to be allowed?

As for some of the other topics, I was part of a team that developed permanent magnet motors for US Navy applications, using Neodymium-Iron-Boron "rare earth" magnets in the rotors. A major concern with these magnets was the well known susceptibility to damage from shock. To address this we selected commercially available grades of NdFeB magnets from over a decade ago that were particularly resistant to demagnetization by shock. This is actually not an unusual characteristic of NdFeB magnets. These magnets, however, were still susceptible to cracking and fragmenting due to their relatively poor mechanical properties, especially in tension and bending.

To overcome this characteristic we "broke" the magnets into smaller near cube shapes (good geometry for a magnet to resist tensile and bending loads), and then packaged them so they were unable to turn, flip or otherwise change their orientation in the motor rotor. This concept has been tested in shock tests to over 200g's at over 80*C without any degradation.

Today there are many more, significantly improved grades of NdFeB magnets, and, considering the application you have in mind, it should not be difficult to select a suitable magnet for under $30, with a few spares. The question at hand is does the use of a magnet violate the FIRST rules for 2004? Has this been posed in the Question and Answer area yet?

Thanks, Jim

Re: Magnets allowed?¿?
 

It really isn't a matter of FIRST allowing magnets. The issue is that using magnets strong enough to hold up a robot would be safe. Personally I really do not see how it can be done. Especially reading about how it can affect people with medical devices.