Power/failsafe LED

[mute]

Power/failsafe LED

*Rant mode ON*

You know what is rediculous.... the way people are making a very simple matter into something very complex!

For gods sake people, its an LED. Fit a LED or cluster of LEDs that come on when you stick the link in and go off when its taken out.

Jim, you use a BEC dont you to power your reciever? If you do surely all of the LEDs (no matter how many hundereds you intend to fit, or no matter what they are connected to) will go out (assuming all capacitors are discharged) when you pull the link?

If we are having this much trouble with a LED, god help us when it comes to spinners, hydraulics and pneumatics, etc....

Flame me all you like because in my view all of this well the rule says... is a real waste of time!

*Rant mode OFF*

[m2xt]

Power/failsafe LED

Mark, I am rather taken aback by your agressive response. Jim has summed up things rather well, this rule whilst it has the best intentions has never been sufficiently thought through - this is proven by the size and content of this thread. I did comply until Stus post, I even went over-board with multi-led cluster lamps, one for link and one for remote kill. However, I do have an additional LED array for voltage level on the receiver supply that do not extinguish when I pull the link.

I will make a fuss when I get kicked out when I have complied with the rules as written as Im sure anyone else will do as well. I had hoped that the days of vague rules aka mentorn were past but regretfully not.

Paul

[babeth]

Power/failsafe LED

*applauds Daniel*

Look, it is simply a matter of indicating where the Power LED is.

[jim]

Power/failsafe LED

*Rant mode continued!* (I like this mode)

For gods sake people, its an LED. Fit a LED or cluster of LEDs that come on when you stick the link in and go off when its taken out.

Thats fine. Thats what the rules say. But the idea that you cant have any LEDs other than this that stay on after the link has been pulled is a new one - it isnt mentioned in the rules at all.

I dont use a BEC at the moment, although I have used one in the past. The arguments http://www.fightingrobots.co.uk/disc...086350736>here

[fluppet]

Power/failsafe LED

At the risk of being on-topic for once, even if my knowledge of the subject is based on paranoia rather than experience...

I know this doesnt seem to be current practice, but I was under the impression that the idea of a link was to remove all electrical power from the robot (not just drive). If the link gets shorted so that theres power to the drive, the first accidental nudge of a transmitter is going to cause trouble. (Im presuming that the shorting in question happens across the LED as well as across the link - although this is an argument for not putting the LED on the link.)

If the receiver is also connected to the link then at least you should spot it not going off (especially if you have telemetry). Actively deciding not to kill the receiver seems dangerous to me. Is there really a problem with driving a relay (switching receiver power) off the main line? Add some capacitance so the main drive goes first if the failsafe is flakey.

I like the original concept that lights off *should* mean dead. Absolutely dead. Not just ought to be dead. You cant guarantee that death is absolutely, er, terminal if the robot has suffered enough internal damage, but leaving bits of it on life support doesnt sound good to me. If all the electronics have power removed, the issue of which LEDs can be on never arises.

But then, Im quite paranoid about designs for this kind of thing. (My machines, when my finances permit me to build them, should be hard to kill - but also hard to activate. Id be inclined to separate the motors too, so the dynamo effect cant cause trouble, btw.)

Id be amenable to the concept of multiple removable links for different parts of the design, if people must keep the parts independent. So long as the removal of *any* of them kills the robot (assuming the failsafes work).

Just my little contribution, before this thread grows to contain more posts than Ive made on the forum in total...

--
Fluppet

[big_nipper]

Power/failsafe LED

Paul, Just read my thread again, it does seem a bit aggressive to you. It was not intended that way and appoligies if it offended you. Your robot does comply with this power light rule as it is written but please see rule 6.4

The rules dont state that there cant be other LEDs on but in my view (not the rules) other lights should also be switched off at the same time. My last statement says simply that the rule is here and for the people who are thinking of ignoring it (ie not fitting a power light) dont ignore it. Common sense tells me that there should be no lights on as how does someone who has not seen your robot before know if its the power light or not. Eg. If you are going out of the pits for a walk and see a robot next to the exit with a light on and no one else around do you walk right past it as if everything is ok or do you report that the robot might still be active? If there are other lights on a robot that are on all the time this confuses people who dont know your robot. Its not in the rules but is (in my opinion) common sense.

This quote taken from the bottom of http://www.fightingrobots.co.uk/forum.htmhttp://www.fightingrobots.co.uk/forum.htm says it clearly:-

Please note that the opinions posted by members of the FRA website may not reflect the opinion of the Fighting Robot Association

Stu clearly thinks the same as I do. But until it is made clear in the rules it is (No offence) an opinion.

But...

Insidendly the rule book says that if there are other switches to remove power (ie Rx battry) then the switchs should be positioned next to each other (ie next to the link):-

Quote 6.4:
All Featherweight, Lightweight, Middleweight, Heavyweight and Superheavyweight Robots must be fitted with on-off switches that operate both radio receiver and drive/weapon circuits - in practice totally removing all power from the Robot. If there is more than one switch, these must be positioned adjacent to one another.

My interpritaton of this is as stated. All power must be removed from the robot. IE if any light is still on then how can all power be removed. They dont have to work from the link as long as they have switches next to the link.

If anyone else wants to comment please read the rules first. If I am still in error then by all means please tell me so.

Quote 4.3:
In addition to the main power light (See. Batteries and Power no. 6.8.) showing the main power is activated. It should also indicate if the robot is in €œfailsafe€, €œoff€ or €œzero€ position.

To answer some of the failsafe lights questions my opinion about this is the rule says should also indicate not must also indicate so I take this as a guideline not a requirement.

Another rule that I noticed and assummed it was a miss print, that has still not been corrected is:

4.8. Maximum allowable TX output is 100 microwatts (standard hobby equipment complies).

I would have to check to be 100% sure but I thought that my Tx was 100 milliwatts as are most Transmitters.

[jim]

Power/failsafe LED

Please excuse me if this sounds confrontational, its not intended to be.

If the link gets shorted so that theres power to the drive, the first accidental nudge of a transmitter is going to cause trouble.
If the receiver wasnt on a separate battery supply, shorting the link would supply power to it too, surely?

I like the original concept that lights off *should* mean dead. Absolutely dead. Not just ought to be dead.
What makes you think that was the original concept? Maybe it was, maybe it wasnt - whichever way, the rule was written before this argument started. Lights off can also mean lights broken, or a broken wire somewhere - we established a while ago that no-one should take the lack of a light to mean the robot was safe.

Id be amenable to the concept of multiple removable links for different parts of the design, if people must keep the parts independent. So long as the removal of *any* of them kills the robot (assuming the failsafes work).
Multiple links are explicitly allowed in the rules. If you add the requirement that removing any links must stop the robot, you have outlawed clusterbots.

Another thing to think about - if removing the link kills the receiver, then reinserting the link will power up the receiver at the same time as your drive. The high power components will then be starting up with undetermined inputs. Not wise.

All this is irrelevant anyway, the original argument is just about indicator lights. I can comply with any rules that are given (Ill just put gaffer tape over any lights that dont go off) I would just like an official answer.

[jim]

Power/failsafe LED

Couple of things about Marks post - in the most part I agree with you.

If you are going out of the pits for a walk and see a robot next to the exit with a light on and no one else around do you walk right past it as if everything is ok or do you report that the robot might still be active? If there are other lights on a robot that are on all the time this confuses people who dont know your robot. Its not in the rules but is (in my opinion) common sense.

That seems a minor problem to me. Thinking a robot is active when it isnt can cause confusion; thinking its not active when it is can be much more serious. Either way its easily solved by clearly labelling the lights, as has been suggested earlier.

Another rule that I noticed and assummed it was a miss print, that has still not been corrected is:
4.8. Maximum allowable TX output is 100 microwatts (standard hobby equipment complies).
I would have to check to be 100% sure but I thought that my Tx was 100 milliwatts as are most Transmitters.

Miss Print has a lot to answer for. It is a typo which has been copied from ruleset to ruleset. My (UHF) transmitter is either 5mW or 10mW, I cant remember which.

[fluppet]

Power/failsafe LED

Jim: Dont worry, Im thick-skinned. (Its skin, I tell you, not fat.) Hopefully Ill make more sense this time round:

Regarding the remote still having power when a shorted link is pulled: yes (I realised my point was woolly as I was making it; sorry). I think my objection is more down to the idea of people having the receiver on but having the robot considered to be safe. That is, by all means power the receiver separately (and let it be switched off separately), but assume that people will consider the robot live until the receiver is off as well - which is probably good practice. So put an LED on *all* the subsystems, but only when theyre all off is the power off. The status of the link being out (when all lights go off) corresponds to all systems being shut down, be they powered directly from the main drive batteries or not.

On that basis, regardless of how many links you have to pull to do it, the robot is safe only when all the lights go out anyway. If people power-down the receiver separately before leaving the arena, that it has a separate light doesnt matter; that fact that the point is under debate makes me assume that people are actually taking the robot somewhere where it can do harm whilst the receiver is live. If Im misinterpreting that, sorry - ignore me. :-)

Regarding lights off *should* be dead - I think this was a phrasing problem; I knew what I meant. Lights on = live we can agree upon; the basis of all this being that a robot with its lights on in the pits is something of which to be bothered. On that basis, although immediately after a fight all bets are off, in general - with a fully functioning robot - we should be designing on the basis that a live robot has lights on it. One could imagine a robot with the light running off a receiver channel which can be turned on remotely; this would be a Bad Thing. We may always be careful around robots (even without batteries, fuel or pressure they could still move under gravity or exhibit sharp edges), but my feeling is that any robot which isnt as safe as it can reasonably be expected to be made at a given point should be illuminated to say so (if were doing this at all, anyway). I dont feel that a robot with the transmitter on but the main drive disabled is in such a state - it should have a light on, and not be allowed anywhere safe.

Youre right, of course, about the clusterbot rules. Obviously the main rules say that you can have multiple links; my argument is that, in addition to having multiple links (on a single robot), any of them should render the robot safe - either by failsafe or by removal of main power.

The point being that of someone needs to pull the link on your device in a hurry (because its activated while youre turning it on, and knocked you unconscious, for example), they shouldnt have to worry *which* link to pull. Rendering the robot absolutely safe may require multiple links, but just one should stop it in its tracks if everythings working as it should.
Theres a distinction between a link and a switch here - Im suggesting that a link should kill weapon and drive (even if its a link with multiple cables running through it), but separate switches for turning them off independently is another matter.

Clusterbots are a special case - its obvious to any newcomer to your machine that each will have a separate link.

You have a valid point about powering up the drive and transmitter in parallel. I should have clarified my point (which I realise Ive now changed slightly anyway): I dont mind two links to power things down completely, but pulling power on the transmitter should, obviously, failsafe the motors - Im still happy with putting the transmitter link in first. That said, its not exactly advanced electronics to put a delay on the motor power going live until the transmitter has initialised.

My point was that I believe you shouldnt have lights which you need to cover with tape, because anything which is on should be off before anyone thinks the robot is safe. By all means have a main drive light to turn off when drive is powered down, but no power should mean *all* the lights are off. Which I think means I agree with Mark. :-)

Incidentally, for the record, if I see a robot which I suspect has power in an electrically noisy and uncontained area such as the pits, what Im *not* going to do is walk up to it and try to read a label next to an LED...

Im not sure that made me sound any more coherent - but Ive tried!

--
Fluppet

[m2xt]

Power/failsafe LED

I have no desire to extend this thread any further than it already is but...

I shall ignor all above posts many of which only cloud the issue. I shall simply comply with the rules as written which I believe state that a power light (which can be any colour, LED or filament, size, shape, flashing or static) has to be fitted in a visible position that shows power is activated. There is no mention that other lights need to extinguish when this power light does. There is no need to fit to featherweights and below. So M2 complies with its lights and TKM2 complies with no lights.

Im happy now and so shall retire to the garage in an attempt to get TKM2 sorted for Newark. Note to self, no more posts to forum as life is too short to get involved in heavy discussions like these.

All the best

Paul

[jim]

Power/failsafe LED

That sounds a lot more clear, but I dont entirely agree about receiver power. If the link complies with the rules, it removes all power to the weapons and drive systems (systems that could cause potential human bodily injury). Receivers and a few microprocessors cannot cause any injury on their own.

Granted, the logic circuits must run off a battery and this could conceivably become connected to the drive side by severe damage. In my case I dont see this as a risk because I only use PP3 batteries, which are too puny to turn a motor. In the general case, I think the risk of this happening is of an order of magnitude lower than the link connector becoming shorted by damage.

The other case is that the logic battery becomes connected to the drive or weapon systems by bad design or workmanship in the first place; I also think this is much smaller than the risk that the link wasnt properly wired. Im open to debate about this, though.

Another case you may bring up is that the receiver circuit could activate a solenoid or IC engine throttle. Here, the compressed gas activation valve or IC kill switch just take the place of the removable link, so the situation is analogous to that of electrical system.

[_jl_]

Power/failsafe LED

Now I have a new (possibly stupid) idea....(not just to keep this thread alive and on topic)

We are all talking about LED:s lighting when robot is unsafe. What about the opposite?
A LED and a zener in series, connected in parallell with the link. Zener voltage equals battery voltage -3V (or 2V or 4V or something).
What would this mean?
Link out: LED lit (assuming battery voltage is not too far down)
Link in, independant of battery and connector status: LED off
Any connection to LED broken: LED off
Zener broken: LED off, or if zener shortens, LED burns out quickly = LED off.

As you can see, this might not always show safe, but if it does, it means safe....

[bugs]

Power/failsafe LED

You dont need a zener, just a resistor.
Besides that, this construction is dagerous. The 20mA flowing thru the led would be plenty to charge the capacitors in the speedcontrollers. They would store enought energy to trigger a valve or something.

[_jl_]

Power/failsafe LED

Nope....with a resistor it will, yes, but with a correctly matched zener, it will only charge those capacitors to a maximum of 2-3V, which should not be enough to do anything serious....afaik...

[jim]

Power/failsafe LED

Once the capacitors reach 3V wont the LED go out? If currents flowing through the LED, it has to go somewhere...