Rule 6.3 The Link

the RAF doesnt provide too much for us, its actually BAE systems that provide us with alot on the mechanical side along with other sponsers whove helped us out with numourous things such as batteries etc (o and stu we did have to buy the 2 vantecs!).

the large outer ring was machined for us by BAE out of a solid 1 ton block of steel and they made our titanium cone for us........it really does help if u know the right people!

to start with Tom the ATC were really behind us etc and we had a publicity person that took pics etc at extreme 1. however this year the ATC basically ignored the fact that we had got in etc, someone lost their job over that one i believe. During filming we actually stay in the ATC hut just to the side of the main gates to RAF Newton. This is because we always bring along a group of supporters (this year called the scream team, im sure alot of u know what i mean)

Because of robot wars, i have met THE top officers in both the ATC and the RAF and i believe that the queen will know of our escapades and may be watching in February as our officer in charge of the robot wars project, Mr bennet was asked to right 250 words which will be included in the yearly report about the RAF to the queen. Not so sure thats a good thing! :)

Arise sir Gary :)

Gary - if you think Liz will be watching, could you get her to write a quick letter to the British Broadcasting Corporation asking why they didnt see one of the RAFs battles as important enough to screen? :)

Hi
when I insert my removable link into my robot the main batteries operate a relay which switches on the power to the receiver. I do have a seperate switch for the receiver but that can only switch it on and off if the link isnt in. the switch is there in case the main battery voltage drops below the level required to keep the relay on so the robot remains in control. does this mean my robot would not pass the safty checks?
I cannot see the reason behind having a seperate switch to remove power from the receiver. The removable link is there to remove power from the weapons and drive so whats the point? Also if you remove power from the receiver you almost certainly remove power from any fail safe devices which are likely powered from the receiver.

so is this a sensible rule?

if its an issue of one switch on a safety system... why not?

muppet

if you remove power from the receiver you almost certainly remove power from any fail safe devices which are likely powered from the receiver

also we already have a removable link. A switch for the receiver is just a distraction and an extra vulnerability.

So I repeat what is the point?

Simon

If you remove power from the receiver then your robot should failsafe, if it doesnt then you shouldnt pass tech check.
The switch is there so as the tech check staff can easily check this.
The reason they need to check this is that if your receiver looses power whilst in combat/loading/tech check they need to know the robot will behave itself.

Hope that answers the question.

Sam
FRA Safety Executive

Even if the more sensible way is to power down the Tx.... But thats a whole debate in itself.

Interesting... Our controllers also power the Rx, so ATM we just have the link switching everything on. I can certainly add a separate switch inline with the DC feed if its a requirement for testing though.

John, a seperate power switch for the radio is not a mandatory requirement. As long as you have a way of removing all power from your robot via your link its fine. (See rules 4.10 and 6.4 in the guidelines).

Powering your RX through the speed controllers (As we do in Storm II) is perfectly acceptable.

Ed
http://www.teamstorm.comhttp://www.teamstorm.com

Now Im confused do I have to rewire my bot with a switch to power down the RX or not?

Si
http://www.chompalot.co.ukwww.chompalot.co.uk

Cheers Ed. Suits me- one less thing to fail...

Simon : No.

Ed
http://www.teamstorm.comhttp://www.teamstorm.com

Ed/Simon/John

4.10 in its past form has been removed in version 1.2 of the rules which is due release May 1st.
It was removed after feedback that suggested it was contradictory to rule
6.4, which has also been re-worded in version 1.2 in order to clarify.
This was part of the process of re-wording to make things more clear that has been requested through feedback from the community.

It was always the intention that RX switches be mandatory, this does not constitute a rule change.

To explain a little better why the RX switch is required.
Loss of power to the RX is an entirely different failure mode to loss of signal (i.e turning off of TX). It can result in some systems in not only losing power to the RX but also the failsafe which is in line with it. This can in turn result in a servo based system in the servo staying in last position, which in worst case means the robot will continue to move/power its weapons.
Where a code-based system is utilised, if this is not set up to return to neutral on loss of power, this can also result in a continuation of movement.

To conclude:

An on/off switch for you RX is a mandatory requirement for all Featherweight, Lightweight, Middleweight, Heavyweight and Superheavyweight robots; in practice this switch when off must place your robot in failsafe status.

I hope that clarifies the situation.

Regards
Samuel Jones
FRA Safety Executive

Hi Samuel
No probs Ill do a little rewiring, but, is this switch just for a tech check? if so can I put in a link which defeats the relay which switches on the receiver battery power and just use the receiver power switch to demonstrate power down of the receiver. then after the tech check fix the link back in place and secure with say tywraps so the switch isnt so much of a weakness. Or has it got to be always be able to switch off the receiver even in the arena?

Luckaly I am upgrading away from servos for driveing my direction controlers (now replacing them with speedos) but i still have a servo on the valve (its actually a servo controled valve which was setup with the help of maddox.) However the servo passes through the new Failsafe from technobots (same as the FS-1 i asume). But if the power from the receiver is lost i am asuming that the servo will stay in the last position.

Am I correct? And will this result in Me failing a Teck Check? If It does how can this be avoided?

Thanks for the Help

Regards
Ian

Sam, this requirement for the robot to place your robot in failsafe status when the Rx is off is a departure form the Mentorn rules. This will in effect mean that 4QD DCI boards and some PCM only systems no longer meet the FRA rules.

Where a code-based system is utilised, if this is not set up to return to neutral on loss of power.. The PCM system cannot output a neutral signal (say 1.5mS) because it has lost its power. This means there has to be a further level of failsafe required. Speedos such as Vantecs and Roboteqs are fine because they have their own built in failsafe logic but that is not the case for all. The same consideration has to be applied to weapons channels as well.

If I understand the above correctly, even those bots with BECs require this switch. It may help if you could explain the safety implications behind this new rule and does this switch have to be accessible without the use of tools?

Paul

Sam, dont mean to pick an argument but the way I understand it is that you are going to be altering the tech check to test what happens with a loss of rx power. Have you tried leaving a robot in a room full of other robots and txs and then turned the rx power off while the robot is on the bench and see what happens!

I can understand where you are coming from as Ive seen quite a few flat rx batterys and if they power servos then the failsafes that are powered from them will also fail to work. But if you power the Rx from the main robot battery then I would have thought it to be acecptable to omit the Rx switch as if the rx loses power then so would the speed controller. If the Cables between the Speed controller and Rx became disconnected then the Speed controller would shut down anyway (All models Im aware off)

People should be aware that a good Rx & Tx setup can have an outdoor range of over 1 mile and if there is a kid playing with his remote control car nearby and your robot is in failsafe mode then it could start following his cars movements!

Ive just built a feather speed controller that supplies power to the rx from 4 seperate cables. Does this mean I need an rx switch on each of these or do I have to alter the speed controller to have an Rx power switch. At the moment it only has a removeable link and I know quite a few others that are the same. We also have an IBC speed controller and this also has a BEC would this also mean I have to switch this!

If its required then I should have read the rules better and will change the robots but I dont have time to do it before Wales.

Just to refresh my views. If you have a seperate Rx battery then there must be a Rx switch in addition to the link, but only if you have a seperate Rx battery.

Ok.
Were aware that there are issues with this rule for some RX set-ups and the safety committee currently have it under review and testing to see if theres a more all encompassing way of wording the rule.

For now though Ill make it as simple as possible.

A robot on loss of power to the RX must failsafe/cease movement on both weapons and drives.

A way for the Tech check personnel to check that the robot does failsafe/cease movement under these conditions must be built into the robot and be easily accessible during tech check.

This is a common failure mode that people need to take in to consideration when building their robots.

Since we at present cant guarantee an arena that will contain all eventualities at ALL events we have no other option but to make sure the build rules cover all the failure modes were aware of.

Hope that helps

Sam
FRA Safety Executive

A couple of things:

1. I thought all arenas had a classification and should be able to contain a run away bot if it fails safe or not.

2. If the Rx is powered by a battery eliminator will you need a switch to simulate a BEC failure?

3. Are we going have a device to simulate what will happen if the Rx Crystal falls out as I have seen this happen a number of times?

Also are provisions going to be made to test all combinations of PCM/PPM & Speedo/Interface for this new mode of failure? Id hate to turn up to an event only to be banned by a new rule!

This is indeed a complex issue because of the variety of control systems employed on our bots. I would argue that all arenas running heavyweights must be able to cope with a runaway bot (the same could not be said just 2 short years ago!). However, I believe we must not only consider what happens in combat but also at home and during testing. The FRA as a competent body should at the very least make this an advisory rule for now while further research is made.

I for one feel the FRA should be congratulated on trying to make our sport as safe as practicable even if it has not fully understood the impact on existing bots of rule changes like this.

Paul

so are you basiclly saying that all Rxs must have a power switch, no matter how they are powered? if you run off a BEC why would you want the main power on but the Rx off?

Im not saying that, I agree that it makes sense that a robot should come to a halt if it loses receiver supply. Whether it should be part of a tech check is questionable as long as the arena is of suitable class. Appropriate design should infer the correct functionality. This is a personal view I should add

Paul

Alan, if I have been reading this correctly the switch on the rx is there to test the failsafe system so the roboteer can prove during tech. check that a power loss to the rx will fail safe. Any means of powering the rx - BEC, battery, elbow-grease - can come unplugged, leaving the main power live but the rx dead.

In an arena it will make no difference, these days, but during testing at home and possibly during power-up something like this could prevent accidents. Of course, Im afraid many roboteers will only think about their failsafe system the day before they are due to get tech. checked...

Would it be satasfactory if my pneumatic weapon was stuck in the closed position (it is locked in a simular way to DanTomKia and Bigger Brother).

At the moment my robot is set to bring the flipper down if failsafe pops in (due to the fact that if someone is in there and i turn on failsafe i dont want the flipper to fly up and hit someone). But it is failsafed by a FS-1 and will stay in the last position if I lose battery power. Is this legal? If not how can i get around this?

Regards
Ian

sorry paul it wasnt aimed at you, i agree with you. Ian i think as long as your flipper remains in one posistion your ok, i think it just to stop your flipper going mad!

Richard - Im a bit wary of the assertion that a modern arena should be able to contain any rogue robots.

Gary may only have been able to damage a side panel in Mentorns arena, not the frame supporting it, but that might not stop a low profile spinner which has decided to stick in drive from being able to get through. 8645T was making a credible attempt to burrow under the arena wall in Debenham. To drive through deliberately would require effort, but its still something which could happen if a robot gets stuck in drive.

If thats not likely enough, theres always the old chestnut of a flipper throwing a spinner into the wall. If Atomic had got T2 over the wall and the impact had caused T2 to do what happened to Behemoth after Mute hit it, bad things could have happened - Makrolon shrapnel at least, and possibly a completely rogue machine.

A modern arena should take any single hit thrown at it (with the possible exception of a big spinner thrown at the outer wall) with an acceptable level of safety, but extending that to an arbitrary number of hits is asking a lot.

It would be very unfortunate for circumstances to combine to endanger the crowd, but the first time it happens (ignoring the idiots running without a screen wherever it was in the US) would be catastrophic for the sport. This is always going to be a somewhat dangerous sport, especially for the roboteers, but lets not take it for granted that the arena will contain everything?

--
Fluppet

Um. Yes, good points there Andrew.

Drags a big spanner over to the works and gets ready to throw it in.

Just been going through the forum to see where I stand with the FRA regards my weapon control for my Hydraulic Jaw. At the moment, and how we ran it in Series 7, is by the good old fashion way of a servo and Micro switches controlling relays to operate the weapon. A FS1 failsafe was used in between the servo and receiver. (fine for the old Mentorn way)
However, reading this thread, and looking at the FRA rules again, I had failed to full appreciate that the robot must failsafe not only with loss of signal, but also loss of power to the receiver. To me this means that No servo/micro switch set up can be used to control weapons or drive systems as servos depend entirely on power to work.

Plus on my understanding, won€™t this also rule out failsafes like the FS1?

However, what grabbed my attention more, and got me questioning my whole system was something Paul mentioned,
Quote,

€˜Sam, this requirement for the robot to place your robot in failsafe status when the Rx is off is a departure form the Mentorn rules. This will in effect mean that 4QD DCI boards and some PCM only systems no longer meet the FRA rules.€™

So some built in failsafes may also not operate with loss of power?
Help!
What can you do to systems that don€™t failsafe on loss of Rx power so they do?
Do the Team Delta RC Switches failsafe with loss of power for example?

You can power the servos and failsafes from a separate power supply to the receiver. All thats required for them to function is common ground and signal wires with the receiver. Of course, if you lose power to the servos then your microswitches will stay in the same position forever.

I dont think powering the servos from a separate power source will increase safety, because its equally likely that the servos power will be cut as it is likely that the receivers power will be cut - but it would satisfy the failsafe on loss of RX power rule.

Theres a couple of things you could do.
Servos can be fitted with return springs so that they move to the off position on loss of power. This is very difficult to get right though with standard servos as they have lots of friction, but if higher quality servos are used, like coreless ones, they are relatively easy to back-drive. Most serious nitro RC car drivers use them (throttle return springs).
The other way would be to have a main power contactor. this could be fed from a smaller relay that was powered by the reciever battery. That way if the reciever lost power, everything would loose power.
Admittedly these are all one more thing that can go wrong, but if you already had a main power contactor, as a remote off switch, like some people have, it wouldnt be that much more complicated to implement this idea.

Mark

Jim, I see what you€™re saying, but as you said, you could loose any power sources to the servo and end up having a micro switch stuck in the €˜on€™ position. As you say, it could get you around the tech check, but I feel there would be a false sense of security about doing this. It wouldn€™t make it safer.

Mark, again I see where you€™re coming from with the return spring, and I think we may have had this discussion on the old RW forum.

On your idea of one main power contactor, One Relay to cut all power to everything. This was how my Robot Victor worked way back in Series 2!
We had all Drive and Weapon power running through a Relay which was activated by a servo/ micro switch set-up. This servo was connected to a failsafe, a G M Services one back in those days, that would cut main power if signal was lost. And just to show how things have moved on, that was the one and only failsafe we had in the whole robot! We stopped using this set up when the removable links were brought in.
This idea could be updated, but my question would be, what would you replace the servo/ micro switch set up with to activate the Relay, which would work if the Rx lost power.

At the moment I have three types of failsafe in my robot, GWS FS-1 units, and the ones built into the Team Delta RCE210 Relay Switch, and the Delbots weapon interface. I€™ve dug out the instructions for all these and all say failsafe mode will activate with loss of signal, None mention anything about loss of Power.

Looking at it, I€™d imagine that the RCE210 would failsafe with loss of power. The FS-1 would fail to de-activate what ever it was connected to with loss of power, and I€™m not sure about the Delbots Board.

Any help, advice or comments would be greatly appreciated.

Guy

With regards to the main power contactor, you could run the power for the contactors coil through a small 6V relay powered by the receiver power supply, then through the microswitch which the servo activates. Arrange for the 6V relay to be downstream of the receiver to minimise the chances of a cut wire leaving the relay powered while the receiver is not.

Regarding servo power - I wouldnt recommend any way of getting around tech checks, it was more to point out a possible flaw in the rule. There are also legitimate reasons for running your servos on a different power supply to the receiver.

Jim when I said getting around the tech check, I didnt mean it in as breaking rules. I was just trying to echo you point about and any power source standing the chance of being cut/lost.
I see where you coming from with the relay running off the receiver power. You could probably do something with out using the servo and micro switch. I still use a switch to switch on my Receiver. You could take a feed after this switch to power a small relay, which in turn powers up a larger relay, which would be inline with the link, which has all power running through it for drive and weapons. Loss of Rx power would shut the relays down, shutting down the Robot.
I guess keeping in the servo and micro switch would give you a remote kill option.

Next to this, any views on the built-in failsafes I mentioned?

Guy

If you use a relay, powered by the receiver power, to supply to the micro switches you will get the same effect as cutting the main power without having to use a heavy duty relay in line with the power link.
i.e. if the receiver power fails, the small relay drops out, no power to the micro switches, no power to whatever the micro switches were controlling, even when the servo operating them loses power and stops where it is.

If you are using interfaces that do not always failsafe by removing the drive to your speed controllers, then power them via the same small relay as well.
That will remove the drive to the speedos.

I have experimented with heavy duty relays to cut the main power and found two main problems with them.
1) Their contacts can bounce open with severe shock.
2) They are not cheap.

Using a 12 volt car starter relay via a resistor from 24 volts is hopeless, they over heat long before the end of a five minute bout.

Reliable 24 volt heavy current relays cost about £30.
They are not easy to find second hand either.

I wish Id bought one of the 180A relays that Maplin used to sell - they were selling them for £9.99. I believe they were sold under the Shark brand name who make lots of cheap car audio accessories. If anyone sees them on sale anywhere please let us know.

180A may not be enough for some modern robots but would do fine for me. As for contacts bouncing open - I have heard several different stories about how likely this is. The biggest problem I expect would be them opening while the controllers are trying to dump energy back into the battery - could cause welding of the contacts and damage to the speed controller.

I agree with Roger about car starter relays or solenoids as theyre often called - theyre not meant to conduct for more than a few seconds.

http://www.albright.co.uk/http://www.albright.co.uk/ sell a wide range of heavy duty DC contactors at reasonable prices. Everything from 80A to 1800A!


Dominic

http://www.ukrobotics.comhttp://www.ukrobotics.com

Theyre quite cheap too!

You seem to be mising the point. You do not need to buy a power relay if you use a small relay powered from your receiver power to control the supply to your interfaces or micro switch driven devices.
If the receiver power is missing, the power to the microswitches or interfaces is removed thus removing the power to whatever they were controlling.

At some point you need to have a device capable of switching or regulating the power from your batteries to your motors. Normally this is a MOSFET speed controller or weapon-firing relay. Both types are capable of failing in such a way that they will conduct power without any voltage supply to their control inputs, leaving you stuck in forward drive or with a flywheel stuck on.

You may find this risk acceptable, indeed it is fine by the current FRA rules, however, a separate power relay reduces this risk significantly.