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Wobbles of Doom! Lucky to have avoided a crash!


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Ah, the Wobbles of Doom. I like it, and a very appropriate name. Glad you came out the other end in one piece :thumbup:

Thanks for the data - the wobble is clearly seen at 21:09 ^_^

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Is the wheel losing traction and trying to compensate?

The jerky wobbles are skary but in essence it wants to stay upright. You just have to try and slow down gently or ride it out. Like pushing the clutch when you feel your wheels just spinning.

Am I completely off here? What was it about you think?

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It's probably a lot to do with the cold evening temperature and head wind tonight in addition to the higher average speed of 30.8 kph over my trip.  Also I was accelerating up some stretches of hill.  The Tesla power is addicting and crazy.  It just gives and gives when you ask it to. 

I gotta remove my speaker as it isn't helping. 

Here's the telemetry from the same route, but it was warmer and the average speed was lower. 

Screenshot_20180523-203033.png

Screenshot_20180523-203039.png

Screenshot_20180523-203047.png


 

Edited by Hunka Hunka Burning Love
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As a beginner I was worried about this wobble thing until I experienced it the first time.  I was tied and sore from learning when it started.  I could tell it was a feedback loop error on my part.  AKA what Keith said.  That and loose ankle joints. I thing you can also turn out of it. Or zig zag like Chooch

Edited by RockyTop
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I get wobbles on my V8 if my feet are centered on the pedal, particularly when braking. Forward placement is a much more stable ride. I liked the idea of a more rearward stance to reduce acceleration and increase breaking but not at the price of the wobbles. 

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5 hours ago, Hunka Hunka Burning Love said:

Luckily I rode through it and brought it under control.  :efefc8626c:  Here's some telemetry data.   The battery started at 100% and ended at 31% after 19 km. 

Ou are lucky! Glad your safe! Are there any irregularities on the terrain were you were riding (ie: stick, tree root, stones...etc?) Personally  I would go back to the scene and inspect the area.  Situations like these weigh heavily on a rider until there are some sound answers leading to the cause. 

3 hours ago, Keith said:

But what exactly causes the wobbles to start in the first place in order to then start over correcting them?

That is a great question. I know in my case it was a hitting a large pothole. In Hunka’s case who knows. I find it hard to fathon that attaching a BT speaker to Tesla’s body would initiate a wooble. 

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6 hours ago, Hunka Hunka Burning Love said:

:efee96588e:  Good thing I wore my big boy diaper pants today.  It was cold and a little rainy, but I decided to go for a spin along my usual route anyways.  I was a little tired from today so I thought what better way than a ride to help revitalize the energy levels.  :w00t2:

Halfway into my ride and stopping briefly to secure my BT speaker at the top of a slight downhill path, I hopped back on and headed down the slope like I've done many, many times before.  What I didn't expect was encountering a really bad case of the wobbles while accelerating to about 40 kph.  I've had some minor oscillations before, but those were nothing like this.  I nearly had to bail as the wheel approached the edge of the pathway and the dropoff into the valley below.  The Tesla was veering quickly side to side about a foot in either direction.  Add to that I'm headed downhill, and it was very hard to brake during this crazy shimmy. 

Usually during a mild wobble I'll lift up one of my heels off the pedal and tilt it onto the ball of the foot which tends to stop the wobbles right away.  The oscillation is definitely self-induced.  With the cold weather and slight fatigue I had the worse case of wobbling I've ever experienced.  In this case there was no way I could lift a heel up - it was wobbling so bad. I don"t think my speaker placement helped matters. 

Luckily I rode through it and brought it under control.  :efefc8626c:  Here's some telemetry data.   The battery started at 100% and ended at 31% after 19 km. 

Screenshot_20180530-213036.png


 

You can see where I stopped to adjust my speaker. 

I didn't realize you could pinch to zoom out and in on this graph. 

 

Anyways, just in case someone else encounters these wobbles, if they aren't severe, try the foot tilt up trick and see if it works for you.  For extreme oscillations just try your best to lean back and slow down.  If anyone else has some tricks, post them up! 

When I wobbles I find clenching the wheel between my calves works to get rid of them

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When you guys say wobble, is that when the wheel is moving side to side and making tiny “s” turns or is it rapid front/back tilting?

I get side to side movements when I try to squat on the wheel. I’m not sure how to prevent that, any advice would be helpful. 

I experienced rapid front/back tilting once on my nb1s1 just before it died. Luckily, it was very slow speed and I was able to get off without getting hurt. 

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7 hours ago, Hunka Hunka Burning Love said:

it was wobbling so bad

The thought comes to mind that the pneumatic tire is uniquely the only 'non-rigid' part of the moving EUC.

Perhaps the unique elastic (rubber sidewall) and pneumatic properties of an inflated EUC tire, under the circumstances of EUC wobble, creates reactively oscillating and turning forces that dampen at lowering speeds.

At 50 psi (arbitrary psi choice) the 170 pound rider with a 30 pound EUC has a  footprint of about 4 square inches pushing against the rotating sidewall (slightly deformed?). You do the math for your specific tire and combined rider+EUC weight.

Monster's tire is 32 psi and has wobbled when the riders center of gravity is rapidly lowered to a some specific point above the Monster at a speed below 20 mph but above 10 mph.

???

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27 minutes ago, Rotciv said:

When you guys say wobble, is that when the wheel is moving side to side and making tiny “s” turns or is it rapid front/back tilting?

I get side to side movements when I try to squat on the wheel. I’m not sure how to prevent that, any advice would be helpful. 

I experienced rapid front/back tilting once on my nb1s1 just before it died. Luckily, it was very slow speed and I was able to get off without getting hurt. 

you can think of it as fishtailing but not slow like a car, fast like a real fish.  lol

Edited by eddiemoy
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More armchair thoughts on wobble:

When wobble occurs the EUC cyclically twists back and forth below the mounted rider in a harmonic way.

The law of Conservation of Momentum (a vector quantity) seems to be appropriate in describing wobble. Before wobble starts the 'twisting wobble vector is zero in magnitude'.

A 'Half-wobble momentum seems to be created by various forces on the EUC tire footprint as a result of the riders center of gravity, the riders pedal input at the axel, motor torque, etc. A half-wobble momentum change in the opposite direction follows  as various forces dissipate the initial half-wobble energy. The net twisting wobble momentum vector equals zero for one complete cycle of wobble (conservation of momentum). Wobble is harmonic when it happens. It cycles back and forth.

The EUC itself also has a substantial forward momentum vector.

The rider is more or less loosely attached to the EUC during wobble and the net controlling effect of the riders downward pressure on the pedals is apparently reduced during the time that wobble occurs which is alarming and sometimes dangerously unsafe.

Since the forward momentum vector is so large (vector quantities map head to toe consecutively and vector length is proportional to its magnitude) the riders path (vector sum) continues more or less on a straight path during wobble.

At decreased speed wobble seems to go away.

Edited by Bob Eisenman
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I'm out on a ride. This story came to mind.

Ancient EU lore recalls the story of the scorned infant Wobble who was the mutant love child of Princess Osmo of the Gimbals and Crown Prince Hathaway of the Shirts.


Wobble's spirit lived on and was known to fear certain disruptions and to cause chaos around him when perturbed in certain ways.

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One more cup of coffee before I go.  To the Valley below.

3 hours ago, Marty Backe said:

You've really turned into a speed demon @Hunka Hunka Burning Love :)

No kidding.  I remember being chided for going over 25 km/h.  What happened to that guy?

Dump the crappy speaker.  Its placement throws off your balance enough that combined with the high speed gave the wobble.

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5 hours ago, Marty Backe said:

You've really turned into a speed demon @Hunka Hunka Burning Love :)

It's all those months limited to 20-22 kph on the ol' Ninebot One E+ that had me yearning to break that speed barrier!  :w00t2:  With more pedestrians there's not much chance to sustain prolonged higher cruising speeds so it's nice on these gloomy days when you have the pathways to yourself.

7 hours ago, Rehab1 said:

Ou are lucky! Glad your safe! Are there any irregularities on the terrain were you were riding (ie: stick, tree root, stones...etc?) Personally  I would go back to the scene and inspect the area.  Situations like these weigh heavily on a rider until there are some sound answers leading to the cause. 

That is a great question. I know in my case it was a hitting a large pothole. In Hunka’s case who knows. I find it hard to fathon that attaching a BT speaker to Tesla’s body would initiate a wooble. 

Thanks!  I'm glad I didn't crash.  It was just like those motorcycle oscillation videos but worse....

The pathway is very smooth on this downhill stretch so I didn't think much of it.  I blame it on uneven foot positioning, my speaker, and leg fatigue.  I usually have my toes overhanging the front of the pedal so nothing really was different there.  Man, the wheel was flailing side to side like a crazy bronco buck.  I'm surprised I didn't crash.

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