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18L Shakes!!!


tsquaremedia

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1 hour ago, Dylan Weidman said:

so I think I figured mine out. I ride hard too and have 3000 miles on this wheel. Turns out the plastic mold that mounts the case to the pedal arms finally fractured away from the case. basically my wheel and my case were barley held together causing the board to freak out. check for fractures to rule this out if you ride hard

I double checked and there is no fractures on my case. 

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On 7/11/2019 at 3:30 AM, tsquaremedia said:

So I ran into an issue today with my Kingsong 18L and hope someone can help me out. As soon as I get on the unit and start riding, it shakes violently until I get off and then it resets itself.

Just a little backgorund, the unit has over 2200kms. I'm a pretty aggressive rider, cruising speed of 43-45km, jumping curbs and riding down stairs quite frequently.

I already opened the unit to see if there was any issues with the control board, loose axle bolts, etc but didn't see anything that caused for concern. Do you think it could be a motor problem, control board or firmware issue? I am running the latest 1.13 firmware.

 

 

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1. Check horizontal calibration when upgrade firmware

2. check whether this happen when the wheel is still, e.g. lift up the handle and push forward or backward to see whether it shakes.

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5 hours ago, Micheal Shen said:

1. Check horizontal calibration when upgrade firmware

2. check whether this happen when the wheel is still, e.g. lift up the handle and push forward or backward to see whether it shakes.

I already performed a calibration and it still has the shakes. 

The wheel does not shake when still or when I’m trolleying it around. It only shakes when there is pressure applied to the pedals or to the front/back end of the wheel with my hands. You can see in the video examples I posted earlier. 

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17 hours ago, Marty Backe said:

Can you please try an experiment with your ACM. Get up to 40km/h and then pull the hall sensor cable and tell us what happens.

If what you say is correct, I'd love to know at what speed they stop being used.

But I have my doubts that this is a true statement. @esaj, do you know anything about this?

There are so-called "sensorless" motor driving algorithms that rely on the voltage and phase current measurements to timing the motor drive, but I don't know much about the details of motor control algorithms or if such is  used in any wheel:

Quote

Sensorless control (see Sensorless FOC Block Diagram) of AC drives is attractive for cost and reliability considerations. Sensorless control requires derivation of rotor speed information from measured stator voltage and currents in combination with open-loop estimators or closed-loop observers.

All I remember is reading somewhere is that it's pretty hard to get right because of the precise timing requirements on the voltage measurement, and as usual with complex motor algorithms, the math gets somewhat hairy fast... 

Might be able to test by doing what you suggest, using some sort of a jig to hold the tire off the ground with the mainboard visible, speed it up to high speed by gently tilting and then yanking off the hall-sensor -connector, but I doubt anyone really wants to try that  ;)  For science? :P 

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@US69 so I just got a new control board today. I installed it, upgraded the firmware and calibrated the horizon and lift assist but I am still getting the violent shakes when I ride at low speeds 😔

Does this mean I am having issues with the hall sensors/motor?

 

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All right this might be borderline inappropriate... But the title... Since @Hunka Hunka Burning Love isn't around to do it.... Someone else have to step up.

Sorry in advance. Summer holidays approaching fast. 

And I hope the KS16X will be here soon and beat what seems to have become a sad EUC launch tradition from all major brands: bugs, quarks and faults. 

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It really looks like the wheel is building up to these crazy oscillations as soon as you start riding.

I'm not sure the cracks are enough for that. They seem very minor. But maybe it's enough?

For these oscillations to start due to the cracks, the board would have to be loose (moving against the motor/pedal bracket/pedal assembly) and be able to wobble a bit (and then it amplifies the wobbling into this crazy shaking).

  • How loose is the board? Is there any way to tell if these cracks allow the shell to move against the pedal brackets+pedals+motor assembly? Or maybe the board isn't firm in the shell in some other way
  • Did you ever try if the wheel does the same if you push it instead of ride it? If there's differences when you have weight on the pedal bracket (where the cracks are) and when you have not, that would point towards the cracks being the reason.
    If there's no difference... I don't know.
  • Does the wheel go into the same shaking if you switch it on and keep it still and balanced on the spot (but you don't move it which might start the oscillation)?
    Does the wheel go into the same shaking if you move it back and forth (pendulum) on the spot?
    Maybe you can find some behaviors that illuminate the situation...
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17 minutes ago, tsquaremedia said:

So after taking the shell off and taking a closer look, I noticed cracks along the frame right by the wheel axle.

Could this be the reason for the violent shakes?

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First off, I don't know for sure, but... 

I recall someone had a wheel that behaved badly with shakes due to similarly cracks. Now this was not a KS18L or KS18XL, but might have been a KS18a/y/s (the one where you can sit on, tall) or might have been Inmotion V8. 

The problem with cracks like that is you are not connected/locked in place between shell/motor/sensors. It can shift and you get to feel that as shakes/play in motor control/ lag in response. 

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1 hour ago, meepmeepmayer said:

It really looks like the wheel is building up to these crazy oscillations as soon as you start riding.

I'm not sure the cracks are enough for that. They seem very minor. But maybe it's enough?

For these oscillations to start due to the cracks, the board would have to be loose (moving against the motor/pedal bracket/pedal assembly) and be able to wobble a bit (and then it amplifies the wobbling into this crazy shaking).

  • How loose is the board? Is there any way to tell if these cracks allow the shell to move against the pedal brackets+pedals+motor assembly? Or maybe the board isn't firm in the shell in some other way
  • Did you ever try if the wheel does the same if you push it instead of ride it? If there's differences when you have weight on the pedal bracket (where the cracks are) and when you have not, that would point towards the cracks being the reason.
    If there's no difference... I don't know.
  • Does the wheel go into the same shaking if you switch it on and keep it still and balanced on the spot (but you don't move it which might start the oscillation)?
    Does the wheel go into the same shaking if you move it back and forth (pendulum) on the spot?
    Maybe you can find some behaviors that illuminate the situation...

After taking off the batteries and motor, it is evident that the cracks are a lot worst then I expected.

The control board is definitely not loose. The shaking only occurs as I'm moving on the wheel, leaning forward or backwards. It doesn't shake when turned on and balanced against the wall. I can even walk it with the trolley handle with no issues.

 

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4 hours ago, tsquaremedia said:

Does this mean I am having issues with the hall sensors/motor?

looks like you have...other than that i have no idea anymore, sorry!

Edit: After seeing the cracks in your shell, perhaps this goes down just to have loose pedal arms!

You should open the wheel, or at least drop out the wheel/motor underneath.

Seams the pedalarms have got that loose that your shell cracked...and then also the vibrating is coming from this.

 

Can you make a photo of the pedalarms?

 

Sorry for jumping around on the explanations....far away diagnosis is very difficult, and best would be to have a proper repairshop!

 

 

Edited by US69
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This is my guess
because there is a crack in the connection between the outer casing and the pedal arm. When you drive, the outer casing and the motor and control board are inconsistent and produce strong vibration.

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If I don't guess the error, you can stand on the 18L and then calibration, so you don't have a strong vibration when driving.
But it is very likely that when you start 18L, it will vibrate.
For your safety, I still recommend a new shell.

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  • 3 weeks later...
On 7/18/2019 at 5:55 PM, US69 said:

looks like you have...other than that i have no idea anymore, sorry!

Edit: After seeing the cracks in your shell, perhaps this goes down just to have loose pedal arms!

You should open the wheel, or at least drop out the wheel/motor underneath.

Seams the pedalarms have got that loose that your shell cracked...and then also the vibrating is coming from this.

 

Can you make a photo of the pedalarms?

 

Sorry for jumping around on the explanations....far away diagnosis is very difficult, and best would be to have a proper repairshop!

 

 

They did note earlier in the thread they had found a loose axle nut or something, and had tightened it.  It seems possible that not finding that earlier, might have contributed to the extensive cracking.

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