King Song 18a 1360wh top speed fall

[Alex_U]

I fell, rolling on King Song 18a 1360wh at top speed on tarmac, still alive and now I wonder if anyone had the same experience under similar circumstances.

So my story is: after 100 km the wheel android app allowed me to set the upper speed limit at 40 km/hour. I setup my wheel with the following numbers: Class 1 Alarm = 0, Class 2 Alarm = 0, Class 3 Alarm = 38, Ollie Speed = 40 and went to roll with battery fully loaded. After 32 km (more than 60% of power remaining - last and within the very first time I reached 106 km after the only charge) there were slopes on my way and while rolling downhill I reached the speed limit of 40 km/h. The wheel was continuously beeping, but I don’t remember pedals going up as it had been before when the wheel had been locked at 20 km/h (probably it depends on Class Alarm setup numbers). So after rolling at full speed downhill for at least a minute I probably reached the limit of 45 km/h and the wheel completely switched off its internal gyroscope after what I uncontrollably leaned forward and hit the ground. It would have been better, if I had body protection on at that time, but I had nothing but shoes and swimming trunks.

Insane – you might say, but I was completely sure in my wheel, absolutely stable movement on even tarmac and had absolutely no clue, that the wheel could have switched its gyroscope off after reaching that 45 km/h limit. You may experience this, if you switch your King Song 18a 1360wh wheel on, lift it and lean it in air to one side or the other – it will reach 45 km/h pretty quick, after what gyroscope will be switched off, wheel will stop turning, but it will be still powered. And after that you will have to switch the wheel off and on again in order to switch gyroscope on and calibrate a new horizontal level.

So my question is: Can I somehow override wheel setup and force it not to switch gyroscope off, when I reach 45 km/h speed limit?

P.S. I could not find in threads of this site similar story, so please don’t try me hard, if I had missed one.

P.P.S. My condition is more or less good now on the second day after fall, just some skin ripped out, but healing pretty quick – in 2 weeks it will completely renew and in 4 weeks there will be no sign of it I hope.

Edited June 20, 2016 by Alex_U

[esaj]

45km/h crash with no protective gear?   Pretty much all the wheels will power off after reaching max speed, but even if they didn't. the motor wouldn't have enough torque left to keep you balanced (the pedals would still just "fall" forward). AFAIK, you cannot stop the wheel from powering off, just don't ride that fast.

As for the tilt-back not reacting, setting it that high might mean that the motor no longer has enough torque to lift them at that speed. Set it lower.

[Bryan Wells]

I would believe that setting the top speed at 40kph was where the mistake was, but I have no idea. So far my ks-18a 800w  that i constantly hit 30kph with has been rock solid.

[OliverH]

31 minutes ago, esaj said:

45km/h crash with no protective gear?   Pretty much all the wheels will power off after reaching max speed, but even if they didn't. the motor wouldn't have enough torque left to keep you balanced (the pedals would still just "fall" forward). AFAIK, you cannot stop the wheel from powering off, just don't ride that fast.

As for the tilt-back not reacting, setting it that high might mean that the motor no longer has enough torque to lift them at that speed. Set it lower.

Esaj is totally right.

Look on a torque curve or put a power curve in relation to speed and make a second curve with the driving resistance (including balance power).  

Max speed may work with a light driver, fully charged battery on a flat road. You need a small bump and the forces / the torque is not enough. Balancing could take a big part.

A downhill road with that speed and than braking would not be nice. As we can see here there's no safety design at all with today's EUC.

[Cloud]

@Alex_U. Wow, you gotta be careful.  You lucked out with your fall - 40 kph,  no protective gear and only ripped skin? Unicycle gods are real nice to you!

The 40-45 kph speed limit is a the limit with no weight on. Please try not to ride at higher than 35kph, and set your alarm and tiltback to lower than 40. 

Get well soon

[Hunka Hunka Burning Love]

Glad to hear that you're okay and still alive.  Going downhill at 40 kph and falling in swimtrunks?  Wow you must be a Ninja or have a deathwish.  

I'm certainly no expert, but a lift test basically shows you what maximum speed the motor can spin at with no load other than the weight of the rubber tire and inner tube.  When you are riding it there is additional weight and road friction that the motor has to deal with which will affect that maximum speed.  If you put an elephant on it it likely won't be able to go as fast.

Also be aware that manufacturers likely base their stated maximum speeds based on a test subject weighing a certain weight.  If you are lighter than that weight you might be able to go a little faster, but if you are heavier that speed ceiling will be lower.  Anytime you exceed that soft, variable limit the wheel will fail.  It just cannot keep you balanced as it needs to be able to go faster to stop your forwards fall so you have to keep a speed reserve to save you.  Setting the last warning right at the upper limit is asking for trouble.

If you roll downhill over that speed above its limit it's asphalt skin donation time.  Going downhill can be more dangerous as gravity tends to speed you up so you have to watch your speed carefully.  Setting the warnings conservatively to give it 4-5 kph reserve may be a wiser choice.  If you absolutely need a wheel to roll downhill safely at 40-45 kph buy a wheel that can handle your weight going 50-55 kph.  If you need to go 50 kph buy a wheel that can go 55-60 kph and so on.  If you have to ride on the wheel's maximum speed limit and want to ignore the laws of physics and battery power buy lots of health insurance and protective gear and pray.

Edited June 20, 2016 by HunkaHunkaBurningLove

[Bryan Wells]

I noticed if I pick up my 18 with the wheel turned on, it will max out its Freewheel speed at 40kph. Ut probably thought it was freewheeling at that point

[US69]

normally the Ks18 1200 watt can handle 40 kmh...

but there are other questions? whats your weight...was it a msssive downhill? why the tiltback downt work or dif you just not recognize it?

i would have suggest a more safety till motor cut off...test it by pulling up the wheel at about 60percent batterie like in that case...

on your app you can than see the motor cut off max speed....

 

someting went wrong here....after the constantly beeping you SHOULD have slowed down...perhaps because of the downhill where the wheel is not horizontal in any way you do not recognize the tiltback....

do the max cut off test by lifting it up....i guess it will be higher than 45.... but then you weight and bumps also plays a roll...

fact is: wheel warned you by massive beeping that the limit is reached....

[Mistagear]

I dont think you can rely on tilt-back to give sufficient warning above 40kph.

This I think is because, to maintain 40kph or higher, you need to lean forward very hard to counter wind resistance, requiring near maximum power from the batteries. This will leave you with very little margin of reserve power to tilt back pedals.

Unless you have above 80% battery charge, you are taking a huge risk of cut out.

My KS18 1200w which has been modified with a 40% greater diameter wheel (26 inch) has a theoretical top speed 40% higher than the standard  model (40kph + 40% = 56kph) and I recently experienced a cut out at approx 50kph due to insufficient reserve power.. Similar to what Alex_U experienced on a standard diameter wheel.

Despite wearing considerably more safety gear, it's been about 6 weeks recovering (and not back to riding yet) so Alex, you are one, VERY LUCKY rider

 

[johrhoj]

Glad to hear you are healing quickly and did not sustain major injuries.

Having said that, I want to thank you for being "a bit stupid", and teach everyone reading this forum how to deal with those maximum speed specification. I want to add one important important remark to this discussion:

The KS18a 1200W will beep twice when you overcharge the batteries (no matter what speed you are going). If you are already driving with full beeps, the first overcharge warning beeps will go unnoticed. I admit that I have driven on full beeps too, but after my experience yesterday, i will always reduce speed when the double-beep speed alarm goes. 

My experience yesterday was driving my ks18 all the way (depleting the battery). I will make it a new topic later today.

[Jurgen]

Swimming truncks at 45Kmh, really?!!! Man man man, you are one lucky bastard, it's a miracle you're still in one piece.

As Esay already said, any wheel will switch off or drop you at close to max speed. Standing still the motor has 100% torque and (obviously) no speed, at max speed you'll have no torque (to keep upright).

Personally I follow 3 rules: protective gear allways, no riding at max speed (or push it to the llimit) below 60V (80% batt capp.), and no riding below 58V (60% batt capp.) if I can help it. Which in your case with a 1360wh as you stated this leaves you with a effective 'safe' range of around 32Km. With my IPS T680+ I get exactly the same range at 25Kmh, and I'm 100Kg. You didn't state your weight, but even then, 32Km using 40% of your batt seems a lot. Or you are 100kg+ guy that rides continuously at 40kmh+ up and down slopes, or there might be something wrong with the battery.

Good luck healing man, may the Big Rider watch over you on your next runs.

 

 

[Jason McNeil]

On 6/19/2016 at 11:02 AM, Alex_U said:

it will reach 45 km/h pretty quick, after what gyroscope will be switched off, wheel will stop turning,

We haven't received/sold any of the 40kph KS 18s but it sounds like this is something KS need address pretty soon for this variant.  

When visiting the factory, I was told by the Engineers that the 1200W motors had a 10kph safety reserve on them (motor capable of 50kph), but clearly the lift test demonstrates that the control-board limits to 45kph, which isn't a great deal of margin. IMO this Wheel either needs to be reduced to 35kph or the firmware updated to support 50kph in a no-load lift test. 

Edited June 20, 2016 by Jason McNeil

[Jurgen]

2 hours ago, Jason McNeil said:

We haven't received/sold any of the 40kph KS 18s but it sounds like this is something KS need address pretty soon for this variant.  

When visiting the factory, I was told by the Engineers that the 1200W motors had a 10kph safety reserve on them (motor capable of 50kph), but clearly the lift test demonstrates that the control-board limits to 45kph, which isn't a great deal of margin. IMO this Wheel either needs to be reduced to 35kph or the firmware updated to support 50kph in a no-load lift test. 

interesting info. Do you believe a 10KmH difference between the speed limit and no-load lift test max speed is enough (margin of errors)?

My IPS T680+ is limited to 30Kmh, and the no-load lift test shows a (theoretical) max speed of almost 47Kmh.

[Alex_U]

15 hours ago, HunkaHunkaBurningLove said:

If you need to go 50 kph buy a wheel that can go 55-60 kph and so on.

Are there any such wheels on sale?

14 hours ago, KingSong69 said:

 what's your weight...was it a massive downhill? why the tiltback did not work or did you just not recognize it?

do the max cut off test by lifting it up....i guess it will be higher than 45.... but then you weight and bumps also plays a roll...

My weight is 68 kg (150 lb). Downhill angle was less than 5 degrees. The tiltback did not work, I'm pretty sure - I would have definitely noticed if it had worked. I know how the tiltback feels at 20 km/h, at 40 - it should have been no difference.

Max cut off test by lifting up is exactly 45 km/h on my wheel.

Edited June 20, 2016 by Alex_U

[edwin_rm]

Interesting that the 1100W motor-version has the same lift-test cutoff speed as the 800W-motor version.

On my 16 I can easily push to 5 kph over the tiltback setting. I can see how you could, too. Specially downhill.

My recommendation: set the tiltback to 35kph, as you can then push on that to 40kph, leaving you an extra 5 kph safety margin (to avoid hitting the 45kph cutoff). Or alternatively set the beeps to 40kph, and always immediately slow down when you hear beeping.

Do note as well that the cutoff speed will be slightly lower during low voltage conditions. You can test this by doing a lift-test when battery is at 30% for example.

Edited June 20, 2016 by edwin_rm

[Jason McNeil]

2 hours ago, Jurgen said:

Do you believe a 10KmH difference between the speed limit and no-load lift test max speed is enough (margin of errors)?

It's just a theory, but it's awfully suspicious that both KS & GW have a cut-off speed of 45kph in a 'no-load' lift test, maybe the PWM IC can only switch up to a maximum rate? @esaj & @lizardmech, along with some of the other resident experts, might be in a better position than I am to indicate whether this is true or not.

[esaj]

3 minutes ago, Jason McNeil said:

It's just a theory, but it's awfully suspicious that both KS & GW have a cut-off speed of 45kph in a 'no-load' lift test, maybe the PWM IC can only switch up to a maximum rate? @esaj & @lizardmech, along with some of the other resident experts, might be in a better position than I am to indicate whether this is true or not.

Not that familiar with the capabilities of the driver ICs, as I've only built the drivers from discrete components, but I doubt it's an issue. Based on what I know, usually in motor-drives the PWM-frequency doesn't change, only the duty cycle.

[Alex_U]

14 hours ago, Mistagear said:

Despite wearing considerably more safety gear, it's been about 6 weeks recovering (and not back to riding yet) so Alex, you are one, VERY LUCKY rider

Probably I am, but I had not recognized it until I read your posts, lads. My injuries are on the pictures (3 days after fall). Now I understand, I was very lucky on that day. Right after falling I checked my condition - there was no bleeding. Those were excellent news, because there was 7 km to my home to roll. After I checked my wheel: switched it off and on, re-established gyroscope, everything seemed OK.

I don't remember any strong pain at that moment, just was a bit disappointed that people in passing cars saw me falling (it happened on a highway). A man on a rolling wheel is rare in our region, it's a kinda like a legend, like a unicorn - everyone talks about it, but few have really seen it. A man rolling at 40 km/h is even more unique - you start realizing that cars, overtaking you, are not that fast any more. A man falling at 45 km/h on tarmac is just a show and you feel yourself a central clown - not a good feeling, I might add.

Anyway, I stepped on pedals and started rolling in 2 minutes after fall. In a few seconds of vertical position I felt there was something wrong with my eyes - black cloud started growing right from the centre to periphery. It was an absolutely shiny day, no clouds in the sky, almost midday and I could not see anything in front of me. I understood that if I had continued then I would have lost my conscience. I stopped, bent myself forward and started intensively breathing. In bent position it really felt better, vision recovered. I rolled again, but in a few seconds of vertical position there was the same effect. As I understand now, my brain had not finished by that time analysing how damaged my body was in and outside, in other words it was the total integrity check of all my organs. And until it's done, the brain really wanted to stop me and the only way to do that was to power off my conscience. I resisted. For the third time I stepped on pedals. It's really strange, I absolutely controlled my balance, but could not control my vision - black growing stain right in the middle again. And when stopped and bent again, I felt something different in my head - that was a feeling of light cold. I understood, my brain had finished its analysis and would not have tried to stop me any more. After that I rolled home without stops. I have to say I did not hit my head and had no headache neither then, nor now.

[Alex_U]

5 hours ago, Jason McNeil said:

When visiting the factory, I was told by the Engineers that the 1200W motors had a 10kph safety reserve on them (motor capable of 50kph), but clearly the lift test demonstrates that the control-board limits to 45kph, which isn't a great deal of margin. IMO this Wheel either needs to be reduced to 35kph or the firmware updated to support 50kph in a no-load lift test. 

Absolutely right. There should be a fool-proof. I was absolutely sure, that first of all the wheel would have tilted back at 40 km/h as it did at 20. But secondly I could not have expected that it would have cut itself off at 45 (I did a lift test on the second day after fall only and had not known that before). And the problem is not related to insufficient power, it's a program bug - too low margin. I'm pretty sure there was more than enough power in my wheel to let me roll and roll, but reaching that speed limit of 45 and programmed power cut off was a back stab, I could not have imagined. Now I know the root cause.

Who should I ask to improve firmware to do it one way (reduction to 35) or the other (power cut off speed limit increase to 50 kph)?

Edited June 20, 2016 by Alex_U

[Alex_U]

38 minutes ago, edwin_rm said:

My recommendation: set the tiltback to 35kph,

I will definitely follow these recommendation, because they are all logical. But what Alarm trigger in App Menu can do that: 1, 2, 3 or Ollie? I tried to figure it out on the second day, but did not complete my trials due to lack of time.

[Hunka Hunka Burning Love]

6 hours ago, Alex_U said:

Are there any such wheels on sale?

.

I was actually just trying to make a point and not really trying to pinpoint any real, existing EUC's capable of certain maximum speeds.  For example, I can ride my NB1E+ at 22 pkh which is perfectly fast enough for me, and I have a reserve speed of about 27 KPH which can save me in the event I speed up going downhill or accidentally go faster.  It may not save me if I overlean for fast acceleration at 22 KPH so I don't do that.  For you, if you need a wheel that goes 45-50 downhill, you need a wheel that has a reserve speed of 5-10 KPH so about 60 KPH to handle what you're asking of it without failing.  That wheel may not exist today, but it likely will in the future so if you absolutely need to go that fast, wait for it.  For your existing wheel, likely a top speed of 35-40 KPH can be possible if ridden carefully, but it should have 5 or more KPH reserve speed throughout the battery charge range to keep you balanced in various situations (speed increase, overlean, etc).  I think in your case you took it to 45 KPH which likely is the terminal velocity quite quickly before it could do any tiltback.

I'm no physicsologist, but my theory is that if your acceleration demand rate through either leaning or accerating downhill is greater than the programmed acceleration rate to create tiltback, the wheel cannot provide it.  That may be why people don't sense any tiltback.  To perform tiltback, there has to be a controlled amount of acceleration I believe to tilt the rider at an upwards pedal angle.  If the rider is exceeding that acceleration, the wheel just doesn't have enough power to over-accelerate the acceleration.  Does that make any sense? 

I think where maybe manufacturers confuse buyers is when they state a maximum speed 45 KPH for example.  If that's more of a terminal velocity before failure it can give buyers an unsafe impression that they can push the wheel up to that speed without problems.  The problem is that if they go 1 KPH faster for example, the wheel cannot deal with it and balance is lost.  Perhaps we should reference the top speed before faceplant (TSBF) as terminal velocity so it's clearer?  I don't know.  If a lift test results in a top speed of 45 KPH without load the terminal velocity under load likely will be a lot lower.  Now, I'm no electrical or mechanical engineer, but I'm just going by what my brain tells me so take that with a grain of salt. 

One other thing is that mandatory tiltback might be a good safety feature, but it must be foolproof regardless of how fast or quick the velocity or acceleration request by the user is.  People don't fully understand how EUC's work for the most part so these safeties have to be implemented with maybe an option to turn them off for professional riders that have to checkmark a disclaimer when doing so.  I think though that it is difficult to program a tiltback to smoothly engage when there is a sudden high acceleration request.  The tiltback acceleration would have to be even higher and could be unsettling.  Maybe a vibration warning before TSBF could help, but if the acceleration is too great there would be little warning.  There's no easy way to slow a leaning object in balance unless that object helps by leaning back.  Unless there is a reserve power boost pack to save faceplants specifically added to a wheel that creates a strong enough tiltback no matter what the current acceleration and torque requests are on the wheel, it's probably best just to have the app limit the tiltback setting safely below the terminal velocity while taking in consideration battery power remaining.

I also think you may have experienced a state of shock with the tunnel vision.  You went through a traumatic crash so your fight or flight reaction was in full effect with adrenaline (epinephrine) released.  After the crash your system has a let down response where things are trying to return back to normal, but the sudden reduction in blood pressure maybe caused your brain and ocular systems to start shutting down resulting in a near faint.  It's just biology.  After car crashes or other trauma, people can go into a state of shock which can make them pass out.  I nearly passed out after watching some OR surgery procedures where you could see and smell the large amount of blood.  There's a sweet metallic sickly smell that is pretty distinctive that you don't normally experience unless there is a lot of blood nearby.

You might be wise to have yourself checked out just in case as some injuries or concussions can be difficult to self diagnose.  Those do look like mostly superficial abrasions and bruising so hopefully it's no big deal as you mentioned.  Keep in mind that middle meningeal artery ruptures can be quite serious.  Or so says House MD. 

Edited June 21, 2016 by HunkaHunkaBurningLove

[Jurgen]

55 minutes ago, Jason McNeil said:

It's just a theory, but it's awfully suspicious that both KS & GW have a cut-off speed of 45kph in a 'no-load' lift test, maybe the PWM IC can only switch up to a maximum rate? @esaj & @lizardmech, along with some of the other resident experts, might be in a better position than I am to indicate whether this is true or not.

If it were a cut-off speed of 25kph, allowing the user to set the max speed to 20kph, that's a 25% safety margin.

With a cut-off speed of 45kph, allowing the user to set the max speed to 40kph, that's just a 12,5% safety margin, at a speed where a lot of things can go wrong???

Could just be that the techies have not thought it through, and just raised the speed without adapting the algorithm/design. But why, if the motor is capable of 50kph?

I think it's worthwile investigating before somebody gets killed.

 

[steve454]

20 hours ago, esaj said:

45km/h crash with no protective gear?   Pretty much all the wheels will power off after reaching max speed, but even if they didn't. the motor wouldn't have enough torque left to keep you balanced (the pedals would still just "fall" forward). AFAIK, you cannot stop the wheel from powering off, just don't ride that fast.

As for the tilt-back not reacting, setting it that high might mean that the motor no longer has enough torque to lift them at that speed. Set it lower.

Good emoji, that is extremely fast to fall from.

[steve454]

2 hours ago, Alex_U said:

Probably I am, but I had not recognized it until I read your posts, lads. My injuries are on the pictures (3 days after fall). Now I understand, I was very lucky on that day. Right after falling I checked my condition - there was no bleeding. Those were excellent news, because there was 7 km to my home to roll. After I checked my wheel: switched it off and on, re-established gyroscope, everything seemed OK.

I don't remember any strong pain at that moment, just was a bit disappointed that people in passing cars saw me falling (it happened on a highway). A man on a rolling wheel is rare in our region, it's a kinda like a legend, like a unicorn - everyone talks about it, but few have really seen it. A man rolling at 40 km/h is even more unique - you start realizing that cars, overtaking you, are not that fast any more. A man falling at 45 km/h on tarmac is just a show and you feel yourself a central clown - not a good feeling, I might add.

Anyway, I stepped on pedals and started rolling in 2 minutes after fall. In a few seconds of vertical position I felt there was something wrong with my eyes - black cloud started growing right from the centre to periphery. It was an absolutely shiny day, no clouds in the sky, almost midday and I could not see anything in front of me. I understood that if I had continued then I would have lost my conscience. I stopped, bent myself forward and started intensively breathing. In bent position it really felt better, vision recovered. I rolled again, but in a few seconds of vertical position there was the same effect. As I understand now, my brain had not finished by that time analysing how damaged my body was in and outside, in other words it was the total integrity check of all my organs. And until it's done, the brain really wanted to stop me and the only way to do that was to power off my conscience. I resisted. For the third time I stepped on pedals. It's really strange, I absolutely controlled my balance, but could not control my vision - black growing stain right in the middle again. And when stopped and bent again, I felt something different in my head - that was a feeling of light cold. I understood, my brain had finished its analysis and would not have tried to stop me any more. After that I rolled home without stops. I have to say I did not hit my head and had no headache neither then, nor now.

@Alex_U that is a very good description of your brain stopping you from doing more damage to your body.  It takes a little time for the brain to realize what just happened.  And it prevents more damage if you listen,  but after awhile it's like riding through tiltback and your brain gets used to it and then what?  Super Ow ow ow.

Edited June 20, 2016 by steve454
You did hit your head, you have a concussion.

[edwin_rm]

@Alex_U Ollie = Tiltback. Also, I have experience the "blackout" after a wipeout that you described as well. One time I wrecked and then got back on my unicycle immediately, to save face, as I was embarrassed about falling in public. Because I didn't give my body time to recover, I lost consciousness momentarily and wiped out again! Double the embarrassment! Lesson Learned: always take a few minutes break from riding after a crash, so as to allow the body to process what happened and recover.