Rules regarding safety links?

What are the exact rules in regards to safety links?

I see a lot of people are using a looped deans or similar plug between their positives on lipos.. and i'm sure someone has attempted using a car fuse?

Could it be possible to use something more secure? by that i mean a link that's a solid object similar to that of a household plug fuse setup, (without the fuse) that will not just pop off/get easily knocked off during combat yet its easy and simple enough to be pulled out quickly by an official?

I've been playing with a design for a new type of safety link which i believe meets all the criteria i can find in regards to link but gives you to added security of not failing during combat, which I'll like to take from concept to reality on my current build, but i do need some serious clarification if this could be acceptable for use.

Some photos of my concept... now i offer this concept up freely for anyone to use, ( if its not been done before and i've yet to see a version here) if you want the CAD file just leave a note here in which format you want. The size at present is quite large ( simple Cad mock up) but i see no reason why this couldn't be made to small sizes say 50x30x30mm with the right equipment or much larger for bulky hands.

Attachment 6040Attachment 6041Attachment 6042Attachment 6043

Exact rules are simple. Have to be removable without tools and after removal, no parts of the machine should be powered.

Since Team RCC went to EC3 and EC5 safety links , we didn't suffer from self removing links anymore.

In Kan-Opener we fitted a 3D printed tripple EC5 link.

Nick, the Aussie monsterspinnerbuilder (Shiney, Mr mangle, Sissorhands) uses the XT series of connectors, combined with fuses and a 3D printed retaining block.

I've always used Anderson connectors as the link

Every safety link failure I had in the past was with Anderson links.

My first fight in the arena, Dutch series 1, Project One Vs Blue was lost due a self removing 300A Anderson link.

So there is no reason why i can't use the link i've designed going by the current comments?

I've always disliked the use of using battery links for failsafes, and that is the method when running model powerboats with 40,000 RPM inrunners attached to flex drives with razor sharp props...

My intention is to have this mount flush with the armor of my current project keeping it tidy as well as secure .

further input welcome!

I like the idea of a flush mounting link. In the olden days however, we were told the link had to be removable with a 'bill hook' (a hook on a pole). If this is not still a requirement - definitely worth some experimentation!

For our last version of the robot (which never got to compete) I used 'Detent Pins'
http://im01.itaiwantrade.com/8f79e43...12-360x360.JPG

Which pushed into a hole and connected two copper plates (with holes) together. The pins were 16mm diameter Stainless and not being the best conductor, still got quite hot! We were drawing 1200A peak though.

The pin locks in place until you pull the ring on the top which withdraws the two ball bearings and allows it to come out freely. The body sat inside a counterbored hole so only the little ring stuck out. Testing showed the ring would just be torn off without dislodging the pin in most cases. You could still remove the pin easy enough with a pair of pliars.

Si

http://uk.rs-online.com/web/p/automo...ctors/8961776/

anything stopping you using something like this

I had though about using a similar pin system as the link, but i though they may be frowned upon seeing how just dropping a screwdriver between the shaft it sits in is easily done for overriding the very purpose, i didn't want to have anything or anyone cause dispute over using such a system..

The use of a catched type plug is another good idea which i will not dismiss out of hand.. so thank you for the suggestion, however there is now talk of being able to remove the link with a hook from a distance, and in all fairness not a bad idea in regards to safety, to which again i think some more information about the exact rules will be needed to clarify this, as a catched system such as the above linked plug would not be suitable....

If a link is required to be pulled via a hook on a pole, then another method for using my designed link would be to replace the finger clasp with a couple of sprung loaded ball bearing each side or that of a tension roller which can literally roll in an out of a predetermined groove on the main casing ( similar to those used on cupboard doors as a most basic example) to which the top could be modified to some type of catch which can accept a hook or a finger to pull the link outwards.

Again i don't want to be re-designing the wheel with something like this, its more an innovation to keep the whole unit contained, easily mounted to a bulkhead or frame under armor or flush with the surface of areas unlikely to get hit and reduce if not stop the link failure/ fall out.

On a side note it would also look vastly better and more professional rather then a hanging cable somewhere inside the guts of the machine, I am experimenting with the idea of encasing an LED light to the link so the LED can power directly once the link is inserted making it clear the robot is indeed ON.

Quote:

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Originally Posted by higgeh

http://uk.rs-online.com/web/p/automo...ctors/8961776/

anything stopping you using something like this

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The 46A rating

I'm looking to move from XT60. I find that pins close up a bit and need a wiggle to open them them up now and again. EC5 are nice but can be tricky as they are a tight fit

XT90 is what I'm using, I think most of it's in how you mount it really - if you keep it fairly recessed back from the access point and make sure it can't move too much (with foam, cable ties, padding, not having it just waving around on the end of some wire, etc.) it should prevent 90% of link failures due to impact.

Would something like those Dzus fasteners you get with ring attachments be okay? It's over-centered when in place so it wont come out, but one quarter turn will bring it out? If it has the ring attachment and not the allen key, it can be done tool-free...

Quote:

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Originally Posted by typhoon_driver

The 46A rating

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What did typhoon use gary? I have a faint recollection of wanting to make something to pull that bloody flag out.

"6.1.1 Removable Link
The main power cut-off MUST be a removable link, which must NOT be in place unless the robot is in
the arena or under the supervision of a technician. A key or switch is not allowed.
6.1.2 Accessibility
The link must be positioned in a visible part of the robot's bodywork, fitted away from any operating
weaponry or drive, and this position must be clearly marked.
6.1.3 Covers
The link may be fitted under a cover, but the cover must be able to be opened without the use of tools.
6.1.4 Kill Switch
If the robot uses an internal combustion engine(s), the "Power" cut-off must take the form of a clearly
labelled "Kill" switch. See Section 7 for further details on engines.
6.1.5 Inverted Link
Robots in the heavyweight class that are capable of being driven inverted, having a removable link fitted
that is only accessible when the robot is the right way up, must have a duplicate link fitted in the
opposing panel, so as to allow the robot to be disarmed when inverted."

It's all there in the FRA rules :)

Poles are not used to remove links, even if a robot is out of control, they are just left to run out of power. These machines are far more dangerous than a boat with a propeller on it.

Using the custom link is fine, but far more effort than necessary IMO. In a FW a XT90 or EC5 work fine, and an 100/200A Anderson in a HW. Putting them under a small door held down by a wing nut is pretty common (We even use industrial velcro to cover ours). While people tend to bury their links inside their robots, the links on both our spinners are easily accessible and on the outside of the robot and we have never lost a link.

Side thought, if your custom link breaks and you can't fix it then you may be in trouble fitting a new link if you have some custom housing. Sticking with the standard links like everyone else has its advantages.

Can I ask a question then.

If I was to run a low voltage system say around 5 or 10V with 2 Nmos Fets attached to it in series could I have a removable link that drops the voltage to the NMOS fets and cuts the power? This way the removable link wouldn't need to be rated to the current that you were pulling through the whole bot and it would make everything safe.

Will pop a circuit diagram up later.

Typhoon 2 used a military grade 1000amp connector that was worth a few thousand pounds which was well slotted in. The middleweights used a screw mechanism that had to be unscrewed.

From reading through this, it does seem as though you are overthinking the problem. The link isn't all that big a deal and there will always be the odd one or two that pop out.

Not totally overthinking it just don't like the thought of handling a live 150A connector and if I can have a low voltage low current link then I can use a military connector that isn't succeptible to vibration or shock

Thanks for the replys, i read the rules and have them as my bible for creating my machine, but again there is nothing in there to state that custom devices can't be used, which was the main point of asking for clarification on using a custom part.

in regards to damage to the link, first off it would be built in using tough materials i'm experimenting with the use of 3D printed nylon so it should be a strong unit for the purpose, but i'm also looking into molding's ( something that i do regularly) so there is no reason for it to fail providing it can be mounted in a way to reduce damage.

However damage can occur even in the most unlikely of places regardless of planning but with all machines of doom carrying spares is somewhat of a necessity and i see no reason not to carry 2 or 3 spare parts of the link, which again the way its designed allows for it to be unscrewed/bolted and replaces in only a few minuets (whats 4 retaining screws and 2 contact screws really?)

Again i was looking to do something different keeping the unit contained and more professional looking without causing issues with the tech check.

I know none of you know me or my work in other hobbies but if you did you would understand that my work i treat as art as well as functionality so if it looks just hashed together it get scrubbed and i find something better.

Please keep suggestions coming, input is always welcome.

Quote:

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Originally Posted by higgeh

Not totally overthinking it just don't like the thought of handling a live 150A connector

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Wearing gloves is the easier option.

Similarly my heavyweight link has a pull cord

I think there was something in a ruleset (I can't recall the precise one off the top of my head but it indicates the thought process) that it had to be a direct disconnect rather than going through a relay or regulator of any kind, and since relays can weld shut/be damaged by shock and FETs can go open crcuit if you look at them funny, you can see why a direct disconnect is safer. You can get anti-spark connectors to minimise the risk and it's honestly not something I'd ever be concerned about grabbing. Plus more components always means more parts that can go wrong...

I think of combat robotics as a sort of art too, gods know I fuss over the placement of parts and making it all look logical, but if you're trying to make every single part fit artistically you're going to have your work cut out with the rest of the electronics!