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EUC oscillation insight


Jens Muysoms
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A few days ago my inmotion V8 started oscillating again. I had to bail and it left me with a nasty case of road rash on my elbow and knee. This was the 3th time in around 1000 km that I have driven the wheel that I experienced such a rodeo ride. It is also the second time I crashed because of it.

This left me wondering what could have caused the wheel to behave in such a way. I started thinking about the circumstances of my crashes and I can clearly remember that on both instances I was braking while driving through a gutter with about the same radius as the wheel. Is is possible that this would throw off an oscilloscope and send the wheel in some sort of a wild feedback loop?

The battery on my wheel was almost complety full as I had only ridden for about 400 meters when it happened. I don't have any wheellog data because my phone's aggresive doze function keeps closing the app so I rarely ride with the app open.

So I am turning to the great hive mind that is the EUC forum to see if anyone else has noticed the oscillation occur in similar circumstances. Or did anyone experience oscillation in totally different circumstances? I hope to create some insight that may lead to either safer EUCs or at least to a more knowledgable driving style that can avoid the problem.

Thank you all in advance for sharing any insight that you may have. I will try to go to the spot where I crashed later today and take a picture of the gutter of doom and edit it into this post.

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Forward-backwards oscillation, indicating a problem with the wheel staying level, or sideways wobble?

Sideways is not wheel-related, it's you(r legs).

As far as forwards-backwards is concerned, you can reproducably throw off a Gotway's gyro by going over a cow grate or a similar rapid succession of rattling small bumps. It will progressively tilt forwards until you're on firm ground again, then a simple brake+accelerate will get it level again. So gyros can fail in some situations. But a GW won't oscillate/try to throw you off then.

Inmotions, there was an oscillation problem before, maybe one can reproduce an oscillation in the V8 in some situations? Since you know where it happened, you could try if you dare:efefc8626c:

 

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4 hours ago, meepmeepmayer said:

Forward-backwards oscillation, indicating a problem with the wheel staying level, or sideways wobble?

I am talking about the forward-backwards oscillation, the pedals tilt up and down in rapid succesion. Exactly like in the video that you posted in the linked forum topic when that guy jumps down those stairs.

4 hours ago, meepmeepmayer said:

Since you know where it happened, you could try if you dare:efefc8626c:

Depends, do you have some body armor I can use? preferably with build in airbags. 

I really wish to avoid painting the road with my face again, wounds heal but I don't know if my ego or my confidence is capable of getting hit too frequently.

Since GW and Inmotion have these oscillating problems, is this an inherent problem with EUCs in general, or just a bad design on a few wheels?

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9 hours ago, Ipsiain said:

I get the wobbles when braking from a fast speed. I think in my case its to do with my feet being too far forward on the pedals. 

I usually try to anticipate road and traffic conditions so as to avoid having to slam the brakes. 

Do you get those wobbles every time you brake hard or only on uneven terrain.?

I drive with my feet a bit forward as well, I think it has something to do with gettting your centre of gravity more or less in the middle of the peddal

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I wonder if it's an InMotion specific issue with their firmware as I've never seen any other wheel exhibit that behavior.  For a moment there I thought you were talking about the Wobble of DoomTM which I experienced yesterday, but it looks to be the Nodding Bronco BuckTM syndrome instead.

Definitely gear up, but I wonder if it's possible to relax and ride through it like that guy in the video.  It seems like the firmware is trying its best to find the balance point, but likely the gyro is giving it some mixed readings after a sudden physical jolt to the chip.  I wonder if @Bobwheel might be aware of any firmware updates down the road that addresses this specific problem as I can imagine it's quite alarming when your wheel goes into "Bronco" mode.

Some Gotways will progressively tilt forwards after successive drops or bumps, but it's usually self-correcting and not too problematic.  Ninebot One's used to do something similar, yet I've never noticed it with mine.  I wonder whether playing with the pedal firmness setting might improve the situation.  What you do have it currently set at?

Edited by Hunka Hunka Burning Love
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A few times on the Firewheel I've experienced the phenomenon @meepmeepmayer mentioned while riding over washboard roads. I was traveling about 20kph at the time. If the bumps are spaced just right (probably some resonant frequency of the control circuit timing) the pedals will tilt forwards. I never lost control from it but it's a very scary feeling because it's the only time the pedals dip forward like that.

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10 hours ago, Jens Muysoms said:

Since GW and Inmotion have these oscillating problems, is this an inherent problem with EUCs in general, or just a bad design on a few wheels?

Gotway's oscillation issue was an unspecified firmware bug, which they fixed. No reason (and absolutely no evidence) to expect any oscillation problems on Gotways now. This was a one time thing and it's over.

Same for other brands (KingSong etc), wouldn't know of any oscillation problems.

The Inmotion V8 oscillation (presumably, going by the other thread) seems to be related to the small (2P) battery compared to the wheel's higher power draw in some situations, which creates a delayed and amplified reaction (the bucking), so it's not the gyro, and it seems to be a V8 specific problem (unfortunately, one that is unlikely to be fixed because it would involve reducing the top speed or something, or a rather complicated firmware fix for a 2 year old wheel; so it may always be there). So bad/unlucky design on this specific wheel - you braking plus an extra bump to manage seems to be too much for the wheel if you're unlucky.

--

I'd say the (presumably) cheap gyros in all wheels (probably the same or very similar part) can be thrown off if you try, but that should only affect their level (the tilting forward by rattling, or tilting forward in curves which is caused when the base level drifts over time and which can be fixed by a recalibration). But it should never create oscillation, that makes no sense. So gyro weaknesses is something different and unrelated to oscillations (and it is not really a problem, it can only be reproduced in very specific, predictable situations, so just an interesting curiosity).

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I file this under "more powerful wheels and bigger batteries = always better, even just for safety". Maybe a stronger wheel would be for you if the V8 reaches its limits with you riding it? Better than waiting for the next sudden crash:efef36327c: Other than that, no advice other than to drive (or just brake?) slower so you stress the wheel less. Not exactly a solution...

Edited by meepmeepmayer
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