FBS braking + link system????

Im currently making a new 6kg full body spinner, i was wondering obout where i should locate the link, and so ive read through the thread about typhoons link and decided i will try and take that approach when i realised my centre axle is not at all big enough to have a centre flag.
So....
I have come up with an idea but i have large doubts to wether it will be accepted.
so here goes..
I am thinking of having my lingk, inside the spinner, but there are four 60mm holes in the top of the disc where ther link will be attached,
To stop your fingers from being disected from my hand i will have a servo--type mechanism that when activated with touch the underneath surface of the disc and then locate in a slot so that the disc is unable to move, and then the link is safe to remove!
With this mechanism inplace when the link is taken out, it will still be in place when the link is put in, altho there will be a locking pin in also.
I will also have a link on the underneath of the robot so that if it is flipped the link is still accesable.
Is this atall legal? i dont think it will be but its my only hope so far
Any ideas?
Thanks Grant

Hi Grant,
I dont have any personal experience of FBS but one potential problem i can see would be if the servo mechanism was damaged during a fight and did not engage properly it could be very serious if you stick your fingers inside to remove the link and the locking pin fails before power is removed.

Im sure someone better placed than me to talk about event safety will put a better answer up here at some point but i could not see many events allowing you to pass a tech check with this system in place.

yer that was my tought, even tho my lockin pin will be hand removed, i can locate it in aslong as the disc is not goin very fast, but the servo mech is a possible hazard!
Grant

Grant we have to use large bearings on all our robots to allow us to get a link in.

The feather weight alone uses two 500g bearings which are completely oversized but we need that to fit a flag down. These are the same bearings used in the middleweight.

It is a real pain in the **** but I cant see anyone being happy about a servo mechanism working before the link can be pulled. Sorry to be so bleak!

Would u be able to fit a few wires capable of holding the current down ur shaft? That way, u could perhaps have the link on the very top of the robot and attempt to connect it in such a way that it doesnt spin, crazy idea but one of the only that i think you could use to get around the link problem.

Yer i think i will have to re make all the centre axle then, its only (dont laff untill u herd the rest) 10m axle, BUT..... it doesnt even need that centre axle. it has 7 outer bearingsalong the outer rim to cause minimal movement, and a further 3 around the top so there is no movement, the disc can be safely run withough the centre axle.
I have thought about having a link that is able to rotate, but it seems VERY complex for what im capable with the facilities at school, I am realy impressed with how it has turned out, up until i realised i had to put in a link :sad:
Oh and gary, where do you get those bearings from, and what are the dimentions and prices as i think this may be my only way around it.
If possible could you please email me at coop_bmx@msn.com on how you flag/link works with bearin stats?
Thanks very much for your help!
Grant

so there is no movement

Im not sure that that is a wise idea, it is best to allow some degree of movement in ur disc even if jst a few mm so that not all the of the shock is taken by the bearings around the edge, so perhaps some shock absorbers?

We had the same idea as urself in extreme 1 with the middleweight however the small wheels that we had around the chassis were to absorb the impact and keep the disc spinning correctly so to speak. After 1 five minute battle, all of the wheels were bent or buckled out of position. True they were only an afterthought and werent very strong but still u might want to a have a slight bit of give somewhere.

Ill find out about the bearings and get back to you, although im not sure when that will be.

Okie thanks, well i have an idea for soft small wheels around the outer rim, but i fized with the idea of bearings, but if thats the problem you had then i will change my ideas bakck to smaller shock obsourbing wheels.
Thanks for your help
Grant

Perhaps for FBS the rules could be relaxed. The link is needed for the certainty of it being dead outside of the arena and for being retrieved whilst being nominally dead in the arena.

However, who in their right mind is going to go within a mile of a rogue FBS, let alone try and reach over it to pull out the link? You let the batteries run flat. Anything else is dangerous.

Still needs a link though, if for no other reason than to stop it spinning up before you want it to.

Still a link but it could be allowed to spin on the body, ie would not be available when spinning.

Well i will still have 2 seperate links, one ontop, and one underneath incase its flipped over.
Just my top main link will be underneath the disc, altho i have prcedures to stop the disc spinning!
I may need to rebuild the centre axle but i have also toyed with the idea of having an underneath link like mauler, just very unreliable.
Grant

I think the main thing is that it is bloody scarey removing a link in a full body spinner even when it appears to be fine after a fight. I for one would not want to turn the thing over while its still live to get to the link!

Also, Ive had damage to mine and when I pulled the link it span up! how? well, the wires had been crushed to the body by a vertical crusher (mentioning no names cooper snr) and the pull on the link was enough to short the wire to the body which was used as the negative of the robot, like in a car, and like in Mute. The moral there is, if the link had been on a part that spins Id be typing this with missing fingers.

Just my bit of input, we can have a chat about the FBS at my house warming if you want Grant.

Cheers

James,

The moral of the story is if you are using a negative earth chassis, then use heavy duty insulation on your wires.... like 170A truck motor starter cable :proud:

The insulation on our stuff is TOUGH, so tough that we cut it with a hacksaw - a stanley knife barely marks the stuff.

Why do I get cold shivers when someone mentions Mute and short circuits in the same sentence???

Julian: Call me a wimp, but the idea of relaxing safety restrictions for full body spinners (especially on the grounds that theyre too dangerous to go near anyway) doesnt appeal.

If a robot goes nuts (in the ignoring-remote-kill sense), it probably needs stopping before the batteries go, if only for the sake of the arena. If the accepted procedure is to pin it against the arena wall (with a house robot, in the Robot Wars case) so the link can be pulled, Id be a lot happier with the concept of pulling it out if the thing cant suddenly wrench my arm off should it slip free.

Mind you, presumably most of the time its a problem for the owner, and since I dont intend to build an FBS its not my problem!

--
Fluppet

Hope the reference wasnt taken with offence Daniel, simply adding a respected name to the post as no doubt there were responses of well what a stupid.... on the way if people didnt realize that I wasnt the only one to do this.

For me, if a hypothetical FBS of mine goes out of control (even a 12kg one), Im switching the controller off and waiting for it to fall asleep. Any talk of me going in with it to pull the link will be met with laughter. I would say that for all spinner actually, if I built it, chances are its whip your hand off, so I aint feeding it bits of me thank you very much.

As I said, pulling the link on a perfectly (apparently) fine robot with juice still in the batts is nerve racking enough.

But what if you dont have the luxury of allowing your spinner to run out of power ? Like: people are in immediate danger, cant get away, spinner moving erratically ?
No, I for one will never allow the removable link rule to be bent. It exists for a very solid reason.

When you design/build a robot you should always put the link in mind first, dont save it as an afterthought. I would recommend that to any rooky roboteer... and some of the old ones.

Personally, the only way that seems safe to me is to put your link out of reach of your weapon, then out of the path of your robot, then see how you can make it safer still. Ideally the link would be accessible from all angles in all circumstances but it may never be, but strive towards that goal. The removable link IS practically the most important part of your robot.

Not saying we should relax any rules Babeth, just saying that I will personally refuse to pull the link on any out of control spinner, and some flipper. I would not pull Rips link if hes dancing with aan out of control flipper for example, as Im a big chicken.

To put this in perspecive, James Cooper and I own an arena. We are spending a bucket load of cash bringing it up to what we hope will be a class 1 featherweight arena definition. (this currently is not a class that exists.)

We are not doing this because we felt the old arnea wasnt safe, we are doing it because if...

Tantrum, Vortex, etc etc (Horizon) went ape at the start of the fight, the old arena (while still being able to safely contain it) may have taken significant wall damage while we went for a cup of tea (waiting for the batts to die). There is no question of us opening that arena till the things dead, and there is no way we will allow anyone else in there.

The new arena gives use that luxury. If Horizon (who is allegedly the most powerful featherweight spinner ever built, but Ed is about as keen to disclose info about is as Kermit the Frog is to eat bacon after supper. his call) went out of control, we can reliably say that cease would be called, and if the roboteers fightin him want to spend the next 10 mins or so running away thats up to them (they will not be allowed to attack!) as that arena stays locked til Horizon (for want of a more appropriate example) has fallen asleep. We can then get on with the next fight.

If you dont have the luxuary of allowing the spinner to do this, what situation have you created? it should be in an arena, it should not have people in it, and it should be capable of containing the rogue spinner.

Just my take on things.

I agree with you there james, i cannot see anybody jumping into an arena with an out of control spinner.

The most important thing i feel is,

If the event organiser allows a spinner to fight in the arena, that means the organiser realizes the risk of running that specific robot and is sure that under NO circumstances could the robot escape in a worst case senario.
Therefore there would be no saftey risk in allowing it to go crazy until the battries die.

if there is a saftey risk in allowing this to happen, then the event organiser has made a wrong decision regarding the risks involved with running that specific robot

yer thats ok james, will sort it out at your house warming, btw when is that?
I will bring it along and show you how far ive got,
as Babeth said, put your link out of reach of your weapon, then out of the path of your robot,
Its a FBS, its not very possible, not that i can see anyhow.
And yes i agree with james there, i would much rather leave my batts to die if my robots out of control, and if i put my main robot PloughBot in the areana with horizon and horizon went out of control then i wouldnt complain about mine being in there with it out of control, rather my robot than me :)
tahnks for your help
Grant

This all sounds a little dangerous and very expensive to me. Im quite happy with the concept that nobody should be approaching an uncontrolled robot - but control is a loose thing.

If a full body spinner goes King B, are the opponents really going to be happy about the damage their robots take if they cant get them out of the way? Its not like they can tap out. Saying they can dodge is all very well, but an FBS can shift across the arena at a fair lick if it ricochets off something.

The arena itself may contain anything the robot can do, but its likely to take expensive damage which may weaken it for future use. Im not sure that relying on the batteries dying us so wise, other than as a last resort.

The circumstances Im thinking of are where something can act as house robot, and can act to immobilise the out-of-control machine (although an OOC machine may well immobilise itself by getting wedged in railings, under an angle grinder, or similar). That leaves the question of how you tell the difference between a flat battery and a machine with a loose internal connection (Supernova) which will come back to life when you approach.

Under those circumstances, where the machine is restrained, I think its appropriate to try to remove the link. This presumes that the link can be removed easily, and doesnt involve two hands on the link and two feet on the armour. Leaving an OOC robot wedged with its motors stalled may cause damage to its motors, speed controllers, or other components, and pose a fire risk.

As an example of what Im getting at, if Typhoon went nuts, Id rather see Killalot pin it in the corner of the arena so the link can be (carefully) pulled than leave it to trash the arena (a non-trivial amount of Makrolon) before going flat - even assuming it didnt manage to jump the wall. Similarly if it got wedged in the wall.

Of course Im not suggesting anyone go in the arena while the robots are free to move, but Id consider the above to be the lesser of two evils. Whether its worth risking is highly dependent on circumstances.

Nonetheless, its an option Id rather have than not have. And if Im going to pull the link from an active, out of control robot (under admittedly exceptional circumstances), Id like to keep my fingers when the machine comes back to life, the spinner slips against the wall, or I accidentally dislodge it. I certainly dont want my fingers stuck inside when the thing catches fire.

As for robots escaping... its impossible to cater for *every* worst case scenario. We can keep the level of safety as high as possible, but actually making it impossible for the robots to escape if something weird happens is prohibitively expensive. The old OOTAd spinner thing is very expensive to counter.

Sorry to harp on about this from a position of inexperience, but Im wary of anyone deciding that making the robot safe is the event organizers problem, not theirs. As an arena owner, James may be happy for feathers to do their worst to his creation, but an arena which takes no damage from a heavy doing the same is a rare thing, and there are other factors involved.

Im with Babeth on this one - if its difficult to make the link accessible, try harder. Everyone else has had to. Sorry to be harsh.

--
Fluppet

Yer well thats fair enough,
The most possible way i can think would be to havee a long stick pertruding from underneath the FBS and pull that out, but its VERY likley to be knoked out, or cut off by another disc!
What do you think about that?
Grant

I would have to dissagree there andrew.

first of all, i would definatly (and im sure everyone else does)prefer my machine to get damaged to an out of control machine than me trying to remove the link from an out of control machine.

As to it being extremly expencive if the arena got damaged during the battrey dieing session. So What? as long as it contains the machine so its not a risk to people then im happy. i would much prefer to have a bill for £500 to repair the arena than a lawsuit against me from the person sueing me for injuery.

Dont forget, you can go home and fix your robot or arena no matter how damaged they get. you cant bring someone back to life.

I think its completely down to the event organiser. and being an event organiser myself i know its scary to say lol. but at the end of the day its the Event organiser that says if a specific robot is safe in a specific arena. If they asses all the possible risks and still belive they can contain it in a worst case senario (eg. robot going mad situation) then they are to blame if the robot escapes,hurts somebody during a battle etc...

Thats very true, but also risky to say.
If i took my FBS to an event and they said yes of course we can hold it, without firstly checking how powerfull my robot is, then it causes some damage, then i would blame the event organiser for tellin me its capable of running rather than testing my robot firstly!
But as it goes, the Rc Wars arena is hopefully going to be a class 1 featherweight arena, and so SHOULD hold anything.
cant wait till its done.
Grant

just reading over this thread its quite interesting to see what peoples views are.

Grant your last comment sounds exactly like what happened at series 7 with us when we smashed the arena.

Also The most possible way i can think would be to have a long stick pertruding from underneath the FBS and pull that out.

Well we dont quite have a stick poking out the bottom, we just have it out the top! The link was our first major problem and we did what we thought was best to solve it and i think that most people would agree its one of the best places to put it. It also has the added bonus that if the disc gets unbalanced, the oscilation can pull it free, however it takes a hell of alot to do this but it was done in testing.........no trying to take our link out ideas andrew! :)

It is entirely up to the event organiser as to whether or not they let a robot run. If they are satisfied it meets their requirements and they are happy with it then its their decision to let it run.

And grant about the bearings, they wouldnt be suitable for a 6kg robot, far far too heavy. The two needed would take up 1kg which i dont think would be very good in a effective FBS

ok, Thanks anyway Gary.
I have found two sizes of bearings now that maybe or maybe not suitable. I will finish building my robot and then change all my xle to a much larger one with a centre link but i would rather just get it working so i know im not wasting my time on it lol.
How exactly does your link work Gary?
Thanks Grant

well our current links are very low resistance and are able to carry very large currents, a few stats-

feather - 100amp
light - 200amp
middle - 500amp
heavy - 1000amp (very cool!)

however originally we made our own. At the bottom of the shaft there were two half circle cresent moon shapes of copper which were separated by a few mm. On the bottom of the removable part of the link there was a large round disc of copper which connected the two at the bottom. This screwed threw a thread in the centre of the half circles. This was very simple yet effective and we were actually congratualated by the robot wars crew the first time we entered.

Ok thanks, i have come up with a new, very siple way.
I dont know how i could have missed it, and theres no need for a removable flag, it is solidly in, with a removable link at the top.
Instead of the axle down the centre of the bearing spinning, the outer casing for the bearings spin, and so there is able to have a longe, solid axle straight through the centre of the robot with no problems (hopefully anyway)
Will this be ok?
Grant

it could work however ensure that the shaft is supported as much as it possibly can be

...as it were, Gary.

James: Dont get me wrong - Im not advocating people charging into the arena as soon as their robot starts to go mad. Im just suggesting that there may be circumstances where the robot could be pinned fairly safely (by a house robot, etc.) for at least a brief period (before stalled motors start to burn, house robot batteries die, etc.) but where trying to keep the robot wedged there until its power runs out - assuming one can tell when that is the case - poses some form of hazard which outweighs that of pulling the link.

Perhaps more frequently (and with a less obscure scenario), an out of control robot may appear to have run down, but instead have done a Supernova and merely have a loose power connection. Give it a tug on the link, and it starts moving again. Obviously youve done this from outside the arena, so your ankles are relatively safe, but what about your fingers? If the robot drives off while youre holding the link, chances are your fingertips might sting a bit as the link is tugged out of your hand, but youll feel it going and let go - robots accelerate fast, but not *that* fast. A full body spinner with a mobile link could pull the link away quickly enough to take your fingers with it, then hit your hand with a tooth as it followed through.

I speak, of course, from a completely inexperienced viewpoint, but from a paranoid and cowardly one. I wouldnt be happy with the idea - I could see it going wrong. Mind you, I was always a bit nervous about the idea of sticking an arm through the railings where it could get pinned, too.

Im just trying to think of what can go wrong, and try to avoid it. If it never happens, so much the better.

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Fluppet