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Design an EUC that can protect its rider from control-board/battery failure?


Truong Do
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I hit a cutoff once last year and lost my riding confident for a week, plus I have heard of many serious injuries caused by cutoffs. Everyday I think about cutoff few times while I am still very excited/relaxing riding my wheel. To me a chance of cutoff is higher than a chance of having a car accident. So I am begging the EUC makers out there to invest on researching to reinvent an EUC that would not just stop suddenly when the main control-board/battery fails. There are many of you here, who are very technical, may have some ideas? Like having a secondary/watchdog circuit that can smartly monitor a failure and take over the control and switch the wheel to an aggressive tilt-back instead of just stop suddenly? While paying big bulk for our health insurance, I am willing to pay more for a more reliable wheel. So whatever EUC maker that can do this would win big!

I started riding EUC more than a year ago where only me having it in the group of my friends. Now we have 8 wheels in the group. Someone kept mentioning "I do not want it" is now riding it every day:) Btw, most of us work for Microsoft and I just have a wild idea of making this popular in the big tech companies like Microsoft, Goolge, Facebook where the employees can ride between campus buildings for meetings, lunch or just for being excited:) Then we may get some attention and probably investment or even a new wheel made by one of those tech companies:)

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@MouseWithoutBorders are you sure that you had

33 minutes ago, MouseWithoutBorders said:

EUC that would not just stop suddenly when the main control-board/battery fails

My first assumption would be that you just overburdened the system (motor) like described in  

That's a system immanent limit that has to be known and respected. Or one has to choose a stronger wheel with higher limits.

One can blame the manufacturers that they do not mention this limits or not implement a warning system which prevents such overburdening (like i tried to describe in this topic - but thats only theoretically - no idea if this could really work in the real world. But there are for sure solutions possible)

If this above described overlean is not what happens in your case and you have real battery/motherboard induced cutoffs you have "old" or faulty EUCs which you should return/replace!

PS.: Anyone knows how to delete or insert lines after an pasted topic link like the one below i can't get rid off on android?

 

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1 hour ago, Chriull said:

If this above described overlean is not what happens in your case and you have real battery/motherboard induced cutoffs you have "old" or faulty EUCs which you should return/replace!

You are right! In my case it was the BMS in AirWheel X8 that took care of the battery instead of me. I later then got it shunted plus an home built extended battery pack. All I meant is that an electrical circuit may fail at any time to any wheel.

Btw, I am riding a ks16s now and the last reported cutoff on an ks16s did not seem to have anything related to over-lean/over-power. I am curious knowing more about the investigation of that case though. Before buying the ks16s I had actually spent many hours researching on which branch is the safest and KingSong seems to be the one.

I was the one to introduce this awesome toy to our group and now keep mentioning about how to ride it safety but there is still chance of crash that we are not in control:( I would feel responsible for every fall they make.

Edited by Truong Do
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The only way to make sure a plane's wings don't just suddenly fall off is making sure they are built well enough so they don't just break away in flight. There are no planes with a spare pair of wings.

The only real way to make sure a EUC's electronics don't suddenly fail is to make good enough electronics. I don't see the point in parallel electronics. My opinion.

I'm not so sure you could reasonably have actual redundancy. Seems complicated, it's not just about having a second board that can jump in if the primary one fails. What if a short blocks the motor (mosfet short can be circumvented by circumventing the board, what about other shorts)? What if a battery fails suddenly and you lose power from it? Do you have enough spare power in the other batteries? Can any error be compensated for fast enough? Do you add more possible points if failure with extra circuitry and parts?

And: either you have by definition situations where the wheel uses all its resources and you can't afford to have anything not work, or your wheel can ever use only 50% of its capacity because you need the same amount as a spare (the IPS S5 seems to be doing that?). Which seems stupid (and expensive) to me.

In my opinion, even today's wheels are already very safe from cut-outs. If the manufacturers just used good cables, good mosfets, good other electronics (an order of magnitude stronger than they use today, quality tested components, etc), and they parallel the battery blocks like KS does on their latest wheels so the battery can't fail entirely (that's how I understood it, but BMS must work with that too, not sure here) - that must be enough. Along with strong motors and big enough batteries in the first place. Maybe some small improvements like a board that keeps working if one of the mosfets blows. Not sure if "bigger" redesigns make sense.

How I see it: if you want more safety, don't use a inherently instable self-balancing vehicle. If you are afraid of a plane's wings falling off in flight, don't fly. Make the machine better, instead of problematic redundancy (I'm all for nonproblematic redundancy though:efee47c9c8:).

Edited by meepmeepmayer
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5 minutes ago, meepmeepmayer said:

you need the same amount as a spare (the IPS S5 seems to be doing that?). Which seems stupid (and expensive) to me.

I knew about this and kind of like the idea thinking about safety, but we will see how it goes:)

7 minutes ago, meepmeepmayer said:

and they parallel the battery blocks like KS does on their latest wheels so the battery can't fail entirely (that's how I understood it, but BMS must work with that too, not sure here), and that must be enough (along with strong motors and big enough batteries in the first place).

Nice, they are going to the right direction then:)

7 minutes ago, meepmeepmayer said:

How I see it: if you want more safety, don't use a inherently instable self-balancing vehicle. If you are afraid of a plane's wings falling off in flight, don't fly.

It is unfair to compare an electric circuit to a plane's wing which has super low chance of falling off:) But you may well say a circuit built in Elon Musk's rocket never fail:)

Btw, a plane's wing may have two engines for a reason.

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I'm just worried about unnecessary or outright dangerous or maybe prohibiting stuff being required from our beloved wheels (like in possible regulation). What we need most right now is the same stuff we have now, just (much) better. Not "redundancy" or whatever, not primarily. But I'm the last one to complain about sensible improvements.

Planes can have multiple engines because it's easy to add one without problem. No such part in EUCs, right? That's why I used the wings for analogy.

To get closer to your original topic idea, some thoughts I had:

  • A board the can switch off a failed mosfet in use without problem (that would be a very sensible improvement and should be doable!)
  • Cables that can do 500A indefinitely. I still hate today's thin axles and motor cables, even on the new wheels. Why not just make everything 10 times thicker?
  • (This may be more trouble than it's worth) Some kind of capacitor and basic balancing electronics in the motor, so the wheel can tiltback you to a safe stop even if the electronics suddenly stop working.
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12 minutes ago, meepmeepmayer said:

(This may be more trouble than it's worth) Some kind of capacitor and basic balancing electronics in the motor, so the wheel can tiltback you to a safe stop even if the electronics suddenly stop working.

I like the way you are going into more technical details even though I do not get all of them but hopefully some of this would get heard by the EUC makers out there! Ideas are just ideas, my idea could be as stupid as 99.9% of other ideas out there. I just want to say people would likely choose safety over other things when buying a wheel, especially for ones who commute, not just playing with the wheel like an X game.

47 minutes ago, meepmeepmayer said:

or your wheel can ever use only 50% of its capacity because you need the same amount as a spare

I actually mentioned something related to this in our group chat yesterday by saying "when buying your next wheel, you want to choose a wheel that you would use 50% of its capacity most of the times for safety reason".

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I know more or less nothing about electronics. A capacitor is just something that stores a bit of electricity (like a battery), but this is probably a really bad idea. Instead of a hardware failure causing a cut-out, it might electrocute the rider (to death?) if it gets suddenly discharged in error:efeff54d4a: Not sure...

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31 minutes ago, meepmeepmayer said:

I know more or less nothing about electronics. A capacitor is just something that stores a bit of electricity (like a battery), but this is probably a really bad idea. Instead of a hardware failure causing a cut-out, it might electrocute the rider (to death?) if it gets suddenly discharged in error:efeff54d4a: Not sure...

That might be a good idea.  Electrocute one to death prior to cutout so you cannot feel the pain of a face plant.  We are on to something here!

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18 hours ago, Acturbo said:

That might be a good idea.  Electrocute one to death prior to cutout so you cannot feel the pain of a face plant

We would better encourage, @meepmeepmayer's next idea could be the right one:) Btw, 60V is just at a point where you start getting a little shocked from it unless you touch it by your tongue:D

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How do electric shocks work? Does voltage or amperage count? Charge maybe? I believe a capacitor, suitable to keep a wheel going for 5-10 seconds (for an emergency stop), suddenly discharging will be much more than the normal voltage and current. But hey, instead of the electronics frying, the rider does, so nobody can complain except the relatives if they can figure that out:efee612b4b:

The board that can deal with a blown mosfet is probably a better idea. Not sure how hard or easy it would be to build that.

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