Solenoid Flipper - Lumera

Hello everyone! I wanted to make this thread because it involves something that "Kinda" breaks the rule of the max voltage inside a bot. I've been looking into these Solenoid Kickers and thought to myself that they might be a good alternative to Pneumatic or Hydraulic Flippers. (I have no experience with them and I have tinkered with high voltage projects in my past in fact they were the thing that started getting me interested in the world of electronics!)

This is a video I quickly pulled out but is the exact thing I want to do. Charge a Capacitor bank (in the case of the video there's just a big capacitor) and dump all that power into a solenoid.

I have thought of a few safety precautions and features I'd put on my bot and I would like to list them and also ask if it is possible to actually allow this bot into the arena and compete Or even be allowed in fun fights due to it breaking the max voltage rule and even having the danger of electrocuting the user while fixing the internals.

Here are my safety precaution ideas :

Short link. This would be a link that's wired up to the output of the capacitor bank and will, as the name implies shorts the capacitor bank so there's no way it can charge up. So handling it outside the arena and repairing stuff on the bot is safe

Power link separate to the high voltage driver. Link ONLY for the high voltage driver so without that link nothing will be connected to any power without that being plugged in first.

Making it a subsystem unit with its own separate smaller battery and making it easy to tell what's high-voltage and what's the drive system.

Putting the entire high voltage system in a 3-4mm thick PLA with an aluminum Faraday cage around the entire PLA Enclosure and for it to be connected to battery GND so it can't destroy nearby receivers and general electronics and for the safety of the user so you can't accidentally grab a rogue HV wire lead as its all enclosed in that box.

For repairs, it can be a unit so it can be switched out to a new undamaged unit to prevent the risk of getting electrocuted.

Now onto the triggering and features I want/need to add

For the trigger circuit for the capacitor bank to be dumped into the solenoid, I was thinking of using a thyristor like in this video. ((( ))) They use a higher voltage and higher capacity capacitor bank so I'm sure the thyristor could handle the solenoid no problem. The trigger circuit will most likely be a arduino connected to a small receiver and when the value goes from 0% to 100% it should trigger, thinking of using CH3 switch for that.

For a bit of control and adjustability, I was thinking of Tesla und Mehr's way of controlling his ZVS driver in a way to set a specific voltage. ((( ))) I was at first thinking of using an Arduino too and making it adjustable over the knobs on the transmitter but I believe that wouldn't be that secure because i cant code something that precise and if something messes up inside the Arduino or something happens to the receiver it could get stuck at a high voltage position and no longer respond to me lowering the voltage.

The reason I want it to be adjustable is just for extra controllability and to be able to tune it if the power is too high for example or if the power is too low I can just increase the voltage. The way I would adjust it at the event for extra or lower power is to have a special attachment for my multimeter so it has a XT30 output that will plug into the short link so I can read the voltage of it safely and for me not to have to unscrew stuff and mess around the circuit.

For the potentiometer I would just incorporate that into the PLA enclosure it'll be in so I can adjust it how I want with a screw without having to, once again pull the unit apart and mess with the circuitry. I can see the problem of the potentiometer slightly rotating during big impacts so I will think of a way to somehow "lock" it in place after adjusting the voltage to my liking.

More specifics :
Capacitor bank: 220V 800uF (4 220V 200uF Capacitors in parallel) I might change it to 5.
Energy: 19.36J (would be 24.2J with 5 capacitors)
Charge: 176m Coulombs (220m Coulombs with 5 capacitors)
1.5kg x 10 x 1.3 = 19.5J (should launch a beetle 1 meter into the air)

I will update and add to this thread more and more during the design process and model so it more clearer what I'm talking about and what I'm doing specifically as I can't really explain stuff that well and I just rely on showing what I have in mind than talking from the top of my head. Looking forward to any replies and will do my best to answer any questions

Zitat von Team Explosive

We just recently agreed on a voltage limit of 50 Volts because a combat robot may get ripped apart and then high voltage lines would be exposed.

Might be able to get that working with enough experimentation... I'm fixated on the solenoid flipper idea so I will try to make it work at 50V the way i'm imagining it. Wanted to use 220V as I already have a handful of those capacitors lying around and I could get them for cheaper if anything went wrong and easier to get the required power. Will see what i can do : )
ditching the idea of adjustability then and making sure it's a fixed 50V driver as it just wouldn't make sense to add something adjustable like that with a lower voltage anymore.

Zitat von Runsler

The 50V are also due to german paperwarriors, insurances and stuff.

If i understood that part correctly, anything above 50V may only handled by professionals.

As the arena marshall is very likely not a professional in that sense, that would be problematic.

there might be a solution once an extra beetle arena is there and maybe there could be some workaround (like you're being the only one touching the bot and retrieving it with a stick or whatever), but honestly I doubt it. And as cool as the concept is, the hassle and paperwork around it might just not be worth it if it's somehow possible to stay below 50V.

Oh, I didn't think that German paper warriors and insurance were the things forcing the rule in place. I thought it was at first just a safety precaution for more inexperienced roboteers trying out something new and dangerous and dont really taking in account other stuff that comes along with high voltage and working with it.

For the workaround, I was thinking of the short link I mentioned and for extra added (probably unnecessary unless Adversity is fully mangled and split in half) protection wear some electrical gloves (i don't think fully solid thick rubber gloves because that would be overkill for 220V which is also inside a box and faraday cage over it all hidden inside the bot imo and i only see it as a must in anything that has reached 1000V to be 100% safe )

I will be willing to try to keep it under 50V and still work the way intended because paperwork is not really fun. If I can't manage to get it under 50V I will try the hassle of the paperwork in the worst case just to be able to bring it into the arena and see if it can also be as effective as pneumatics and hydraulics.

Zitat von Runsler

It's one of these cases where "nothing will happen with the right precautions" is good enough for private use, but as soon as the whole Association gets accountable for what might happen a very tiny risk, however small, gets unacceptable. From what i understood, those of us putting the most volunteering work in (by organising everything and managing the whole stucture) and such would at the same time be those having to take the full consequences even with their private money at risk and such. So... Yeah, sadly not a matter of "taking enough precautions", but more "make it somehow fit inside the rules/paperwork", even if the latter might be less safe for th person handling the bot, it's a lot safer for the Association and its "management".

Nevermind then. i am staying within the limit as i don't want to make a stupid bot and get the association in trouble because i like what MMM and GRA do and I don't want to mess anything up and put the entire organization at risk. Will be a bit difficult due to this rule but it doesn't matter I will most definitely find a way around and have been exploring a few other alternative 50v capacitor bank ideas and from what I saw one has a LOT of potential to be as good if not better than the original 220V capacitor bank idea. Thank you for going a bit more into depth because I didn't know much anything about the paperwork and I do not want to screw anything up for the organization and get them in trouble.

So current plan on the circuitry for the Solenoid looks like this. Its quite bulky but I am sure I can design something compact enough but still be able to fix if a specific component dies.

I believe 3S 300mAh is enough for the circuit to function 3 minutes. The regulator circuit also turns off the ZVS driver when the voltage set with the potentiometer is met and will only turn on when it "underloads" so itll be at a stable 50V all the time with no overshoots/undershoots and will also save power. Using it to detect signal on only one capacitor bank as they are both powered by the same transformer so both will get (almost) the exact same voltage and current and will cut off the entire ZVS driver so I believe a second Regulating circuit is not needed.

NCL from the discord server had a brilliant idea to split up the solenoid coil in a number of parallel coils with their own capacitor. That would work a lot better than a single coil. So I'm using two so I dont have to have to complicate anything too much while still getting better performance than a single coil.

Using relays at each coil so they can be turned on in a sequence like a coil gun with individual stages to hopefully raise efficiency, power and save a small bit of power and not load the transformer as much during a flip. And most importantly to isolate the high voltage side entirely from the receiver and Arduino. If I were to use a thyristor and that blows it would be a disaster. So Relays seemed like the obvious choice.

Flyback Transformer and ZVS inductor chokes will use Litzwire so they work better. (and ofcourse the flyback transformers output is directly rectified to DC with a full bridge rectifier.

I wrote capacitor bank but i take it back. i will just use a single 15000uF capacitor at each secondary instead of a bank of 20000uF. I use only 2 capacitors instead of 4. Price is relatively the same and the size and weight is cut in half and i get 18.75J per capacitor before was 25J but its whatever. i am happy with it currently)

Short link will probably be a screw switch instead so i can just screw it in and discharge both with enough screwing (will be fun to make as the capacitor banks aren't wired together and need to be discharged individually with a single screw) Although before using the short screw/link i could just flip one last time with the ZVS driver's link pulled out and discharge it beforehand into the solenoid so the screw wont be abused as much from the short.

Arduino Nano is only there to switch on the relays in a sequence for greater power and to cooperate with the receiver- planning to use CH3 switch to trigger the flip on the transmitter. and maybe even using the left knob on the transmitter to make it able to turn on a single coil so in a emergency where instead of dumping all power into a strong flip and missing i can have 2 weaker flips and maybe toss the opponent away from adversity and then charge up for a big flip. Or in self righting issues if the flip is too powerful and just flips back to the same position a weaker flip could help get back on the wheels without flopping around like a fish with no success.

For the ZVS driver i need a big capacitor on the primary of the transformer and the bigger and beefier it is the faster it'll charge. And i dont want to use something too big so it might charge a bit slower (hence why 2 weaker flips before a big one in emergencies) The gates of each mosfet is connected via 2 diodes to a BJT transistor on the Regulator/Limiter circuit so when the regulator kicks in they will be pulled to ground and turn off.

For now that is all on the circuit side.

On adversity all that has been thought of is instead of 2WD ill have 4wd with timing belts and 2 deadshaft wheels. Planning for the chassis to be 3mm thick aluminum or so with HDPE or TPU wheel guards or so.
For wheels probably diy rubber wheels and maybe cleated wheels aswell

Super SUPER rough sketch because i was bored and just wanted a super quick reality check on how big everything will be (Solenoid and capacitors are To-Scale including the inner thick walls which will be 10mm HDPE) So rest can be ignored as its all wrong sizes

Its going to be VERY hard to make it underweight unless i find smaller capacitors. They are currently the thing eating up the most space.

Energy wise i will go with 25J. The capacitors are cheaper and easier to find and it will still give me a 1.6 meter flip
if all goes well

Parts ordered. Wonder what the mailman will do with almost 10 boxes or so with a username instead of actual name written on it...

Will add a sticker ontop of our intercom (we live in a apartment)

Most of the parts for Lumera have arrived and with that i could begin to work on the CAD. (This is a work in progress. Design will change and get more optimized!

Its going to be a lot of fun optimizing the chassis to be as light as possible. (500g)

Alright where to start.. Solenoids aren't as powerful as i had initially thought. Maybe at 250V-450V would this idea work. But at 50V it has no place in the arena nor in a bot due to the sheer amount of weight the solenoid itself weighs (340g) and added the more special circuitry needed to drive it, power draw, special switching, etc etc is just difficult to make. I've done a few different mechanisms and tests to try to get it to work and only in one did it manage to flip at decent speeds. Though as soon as Lunaris's old beaten up and destroyed chassis (my previous bot) that weighs 217g was put on it it couldn't even lift it and immediately stalled as soon as powered on.

If there were no regulations or rules in place to prevent people from going to stupidly high voltages and currents even then will it be difficult to make it. The amount of power it draws is stupid and would require a special high power switch that is 100% guaranteed to not fail otherwise a lipo fire is most likely gonna occur alongside all the electronics just dying.

Though no worries. I have something else menacing to bring into the arena