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Marty Backe

[1860Wh MSX Warning - Oscillation!] Gotway Repeats The MSuper V3s+ Debacle of 2017

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18 minutes ago, ZenRyder said:

The second problem that Nick and I both had is death wobbles at speed. I had already been up to 29 mph on this new MSX, but it was on a long straight paved bike trail and luckily no hard deceleration was required. But on the hill by my house, which is also very steep I had to stop because of the stop sign at the bottom with likely traffic. So it wasn't an option to accelerate out of it. 

I believe the idea of accelerating out of "wobbles" comes from motorcycles where the idea is to take the weight of the front wheel. If you only have just one wheel, then wouldn't accelerating just mean you crash faster? I'm just a beginner so forgive me if it's a stupid question.

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1 minute ago, mike_bike_kite said:

I believe the idea of accelerating out of "wobbles" comes from motorcycles where the idea is to take the weight of the front wheel. If you only have just one wheel, then wouldn't accelerating just mean you crash faster? I'm just a beginner so forgive me if it's a stupid question.

I thought the idea came from stopping the input (deceleration) which caused the problem. By acceleration I meant no longer leaning hard back to decelerate. So I didn't accelerate but I did attempt to ease off the hard deceleration. Never even had a hint of a single wobble prior to this. Only seems to happen at higher speeds. @Nick McCutcheon, who is much more experienced than me, also experienced the wobbles at higher speeds. 

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Split for visibility.

Are any MSXes affected? Only 100V?

Is the back light not working a sure sign the MSX is bad? If the light works, does that mean you're good?

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Marty, the second video in your post, image stabilization is trying to stabilize the wobble out of the video I suspect, hah.

2 hours ago, mike_bike_kite said:

I believe the idea of accelerating out of "wobbles" comes from motorcycles where the idea is to take the weight of the front wheel. If you only have just one wheel, then wouldn't accelerating just mean you crash faster? I'm just a beginner so forgive me if it's a stupid question.

"When in doubt throttle out," yeah throttle takes pressure off the front tire, which reduces its influence on the bike if wobbles are in progress. If you lift (wheelie) the front tire, just straighten and set back down problem solved but hard to do when the throttle hand is getting whipped all over the place and the bike isn't lined up.  Braking applies larger force to the front and amplifies the problem.  Same effect with cars -- people making an aggressive curve at speed and let off the gas, the weight transfer to the front causes the front to have more control resulting in "snap oversteer" and they go spinning, because they didn't let off the steering while letting off the gas.  I don't think any of this applies to EUCs as there's only one tire.  It does make sense that carving could cure euc fishtail / death wobble.  This is similar to a car with worn out loose steering components -- wobbles when driving straight, but making a curve pins all the forces to one side and becomes steady.

I posted a psa on r/ElectricUnicycle to this thread but I can't pin it.

Edited by xorbe

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I also got a lot of footage of @Nick McCutcheon 's wheel oscillating in action. I'll post the clips here when I get to it.

 

Edit:  YouTube video

Edited by Flyboy10

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4 minutes ago, Jason McNeil said:

GW just advised, that they believe that this instability is a consequence of the internal piezoelectric speaker being in too close proximity to the gyro sensor

:facepalm:

Electromagnetism, how does it work? The electrical engineers at Kingsong (18L) and now Gotway, too, apparently don't know:facepalm:

Is the speaker placement or model different on the 1860Wh MSXes? What changed?

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3 minutes ago, Jason McNeil said:

Latest development on this: GW just advised, that they believe that this instability is a consequence of the internal piezoelectric speaker being in too close proximity to the gyro sensor, at least one Wheel has been tested, it looks promising. Waiting for feedback from a couple other Customers from this batch. If this is the case, the fix is a fairly simple speaker further out from the controller.  

Interesting, I noticed that they moved the speaker up right next to the fan. Here is a picture of the location in the case:

20191119-194150.jpg

You're saying that it will be easy to relocate, but there isn't any other room on this side of the case due to the extra battery pack. That's why they had to move it in the first place. 

There is a lot more room on the other side. 

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8 minutes ago, meepmeepmayer said:

Electromagnetism, how does it work

But piezo doesn't have a magnet or a magnetic field.  What about the rear tail light?

Edited by xorbe

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4 minutes ago, ZenRyder said:

You're saying that it will be easy to relocate, but there isn't any other room on this side of the case due to the extra battery pack. That's why they had to move it in the first place. 

There is a lot more room on the other side. 

I realized how ambiguous this sounds. I have over used the word "other" to make my statement incoherent. 

To clarfy:

There is no more room to the left of the control board because the extra battery pack now fills that spot. 

There is still some room on the opposite side of the wheel. 

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11 minutes ago, xorbe said:

But piezo doesn't have a magnet or a magnetic field.  What about the rear tail light?

I meant mostly that if the sensor is so susceptible to interference, maybe some electromagnetic shielding (aka a metal casing) wouldn't be the worst idea. Right now, it looks like you could build a "zapper" that makes every wheel oscillate!

As far as what causes this, I have to trust what Gotway and Jason say. Good idea with the rear light, though. Maybe it is the culprit, after all it doesn't work in those cases and it seems more likely the rear light interferes with the sensor than the beeper interfering with both the sensor and rear light. On the other hand, the beeper was moved, the rear light was not. And since it has power cables going to it, I think it will do electromagnetism:) Maybe it's the combination of beeper and light, too;)

Edited by meepmeepmayer

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Yeah as an EE, I wouldn't jump to a conclusion on that without digging in.  Just have to wait.

Edited by xorbe

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5 hours ago, ZenRyder said:

You can see the forward/backward oscillation when I'm going down the first hill. It's tilting back and forth. I just put it down to inexperience on my part, but in hindsight and with @Marty Backe 's testing confirm that it's the wheel.

The GPS stops before the crash, but I was probably going 22-25 mph. I have the EUC World logs if it matters. 

The second problem that Nick and I both had is death wobbles at speed. I had already been up to 29 mph on this new MSX, but it was on a long straight paved bike trail and luckily no hard deceleration was required. But on the hill by my house, which is also very steep I had to stop because of the stop sign at the bottom with likely traffic. So it wasn't an option to accelerate out of it. 

Who knew an MSX could fly using those little pedals? :laughbounce2:

Anyway, the fender popped off, but I was able to snap it back on, no problem. The only serious damage was to my pride. :crying:

I am disappointed that this firmware screw-up happened. But overall, I still like the MSX and want to get it fixed ASAP. I'll let you know how it goes. Let me know if you have any questions. 

Yeah, I love watching your MSX do multiple rotations in slo-mo. Sorry :D

There were just shy of 3 complete 360-degree rotations of the wheel in the air. Amazing it wasn't damaged more (usually the pedals hit and they get twisted).

Edited by Marty Backe

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5 hours ago, Planemo said:

I don't know whether to laugh or cry. I have an incoming 1860Wh MSX as I type, expected in 1 to 2 weeks. Ordered from Intelligent Walking Store.

To say I am gutted with this news is an understatement, but I really appreciate you giving us the heads up on this Marty, before someone seriously hurts themselves.

I will be keeping all fingers and toes crossed, and will update once I have confirmed if I am one of the unlucky ones or not.

Do you have experience riding Gotway wheels? Just know that your wheel should ride smooth with zero back and forth oscillation. When riding straight it really should feel like your Z10.

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