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How can you possibly fall off a self balancing scooter?

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Peeler
Guest

Fri Jan 25, 2019 9:45 am   



On Fri, 25 Jan 2019 11:15:07 +1100, Steven, better known as cantankerous
trolling senile geezer Rot Speed, wrote:

<FLUSH all the idiotic trollshit unread again>

....and much better air in here again.

--
Richard addressing Rot Speed:
"Shit you're thick/pathetic excuse for a troll."
MID: <ogoa38$pul$1_at_news.mixmin.net>

NY
Guest

Fri Jan 25, 2019 10:45 am   



"Steven" <shy543_at_gmail.com> wrote in message
news:gav2ojFcs0sU1_at_mid.individual.net...
Quote:
"NY" <me_at_privacy.net> wrote in message
news:Odqdnc3cerV429fBnZ2dnUU78UXNnZ2d_at_brightview.co.uk...
Let's say you're stood stationary and upright on it, not moving. Now,
you lose your balance a little and begin to fall over backwards. Your
feet tilt backwards, the device senses this, and moves backwards.
You're now still over the device

Yes, but it can't move under the center of gravity while your feet are
still on it.

You've forgotten Newton 3: "for every action, there is an equal and
opposite reaction".

Nope.

It moves the wheels by the motor exerting a torque on them. This causes
an equal and opposite torque on the scooter-and-human,

Yes.

thus moving the person's C of G relative to the axle

Nope, because the tilt of the human doesn't change much.


Doesn't it? I've never really watched one in operation that closely.

Quote:
until the C of G is once again directly over the axle.

Fraid not.

This is how it corrects for the person leaning too far forwards or
backwards.

No, it applies force, it doesn't shift the CoG.

If the person leans back, the sensors detect that the scooter is tipping
backwards, and rotates the wheels backwards, thus tipping the person
forwards.

By force, not by moving the CoG


You may well be right: by exerting a forward-twisting force it may
counteract the tendency of the person (whose C of G is still behind the
axle) to twist the platform backwards. I suppose the fact that it does this
allows the person then to move to adjust their own C of G once the platform
is stable again.

Peeler
Guest

Fri Jan 25, 2019 10:45 am   



On Fri, 25 Jan 2019 09:09:42 -0000, NY, the brain damaged, notorious,
troll-feeding senile idiot, babbled again:

<FLUSH those two idiots' endless sick shit unread again>

NY
Guest

Fri Jan 25, 2019 10:45 am   



"Commander Kinsey" <CFKinsey_at_military.org.jp> wrote in message
news:op.zv490lwywdg98l_at_desktop-ga2mpl8.lan...

Quote:
I knew steering played a big part (I thought about 50%) because I've seen
a trick played where people are given bicycles with fixed steering, and
it's very difficult to balance on them.


Also there have been tests where a perfectly balanced human-size/weight
dummy is attached to a bike, and it falls over even when it is travelling at
a speed that a human could ride easily. That suggests that minute
adjustments to balance and steering are a major factor in staying upright.


Quote:
I'm sure the wheels play a big part too - if you remove a bicycle wheel
and keep the hub, then spin it holding the wheelnuts, it's difficult to
turn over. Mind you, maybe that's not enough to prevent the weight of the
rider falling over too.


That's the gyroscopic effect. If the wheel is rotating and you twist the
axle side-to-side (in a horizontal plane), there is a force that tries to
twist the axle up-and-down (in a vertical plane). It acts so as to correct a
tendency to fall over: if you start to lean to the left and the front axle
turns to the left, the gyroscopic force acts to try to move the bike back to
vertical, and its magnitude varies with speed.

I can see why people though that this was the only force that mattered,
since it does play a small part in keeping balance - it's just that it's not
enough on it own.

I read of an experiment where a bike was fitted with wheels that had discs
of equal mass to the wheel that were rotated (electrically) in the opposite
direction so as to cancel out any gyroscopic force. And the bike was still
rideable, though it was slightly harder to keep one's balance.

Peeler
Guest

Fri Jan 25, 2019 4:45 pm   



On Fri, 25 Jan 2019 09:34:50 -0000, NY, the brain damaged, notorious,
troll-feeding senile idiot, babbled again:

<FLUSH another huge load of senile shite>

You seniles STINK of your senility! <BG>

Peeler
Guest

Fri Jan 25, 2019 5:45 pm   



On Fri, 25 Jan 2019 09:34:50 -0000, NY, the brain damaged, notorious,
troll-feeding senile idiot, babbled again:


<FLUSH>

Quote:
direction so as to cancel out any gyroscopic force. And the bike was still
rideable, though it was slightly harder to keep one's balance.


You must be ever so thankful to have found a filthy retarded troll, wanker
and attention whore like Peter Hucker whom you can keep feeding, senile
idiot! LOL

Steve Walker
Guest

Fri Jan 25, 2019 7:45 pm   



On 25/01/2019 09:09, NY wrote:
Quote:
"Steven" <shy543_at_gmail.com> wrote in message
news:gav2ojFcs0sU1_at_mid.individual.net...
"NY" <me_at_privacy.net> wrote in message
news:Odqdnc3cerV429fBnZ2dnUU78UXNnZ2d_at_brightview.co.uk...
Let's say you're stood stationary and upright on it, not moving.
Now, you lose your balance a little and begin to fall over
backwards.  Your feet tilt backwards, the device senses this, and
moves backwards. You're now still over the device

Yes, but it can't move under the center of gravity while your feet
are still on it.

You've forgotten Newton 3: "for every action, there is an equal and
opposite reaction".

Nope.

It moves the wheels by the motor exerting a torque on them. This
causes an equal and opposite torque on the scooter-and-human,

Yes.

thus moving the person's C of G relative to the axle

Nope, because the tilt of the human doesn't change much.

Doesn't it? I've never really watched one in operation that closely.

until the C of G is once again directly over the axle.

Fraid not.

This is how it corrects for the person leaning too far forwards or
backwards.

No, it applies force, it doesn't shift the CoG.

If the person leans back, the sensors detect that the scooter is
tipping backwards, and rotates the wheels backwards, thus tipping the
person forwards.

By force, not by moving the CoG

You may well be right: by exerting a forward-twisting force it may
counteract the tendency of the person (whose C of G is still behind the
axle) to twist the platform backwards. I suppose the fact that it does
this allows the person then to move to adjust their own C of G once the
platform is stable again.


It simply moves the platform and the rider's feet back to below the CoG.
Hence rebalancing.

SteveW

Commander Kinsey
Guest

Mon Jan 28, 2019 9:45 pm   



On Fri, 25 Jan 2019 09:34:50 -0000, NY <me_at_privacy.net> wrote:

Quote:
"Commander Kinsey" <CFKinsey_at_military.org.jp> wrote in message
news:op.zv490lwywdg98l_at_desktop-ga2mpl8.lan...

I knew steering played a big part (I thought about 50%) because I've seen
a trick played where people are given bicycles with fixed steering, and
it's very difficult to balance on them.

Also there have been tests where a perfectly balanced human-size/weight
dummy is attached to a bike, and it falls over even when it is travelling at
a speed that a human could ride easily. That suggests that minute
adjustments to balance and steering are a major factor in staying upright.

I'm sure the wheels play a big part too - if you remove a bicycle wheel
and keep the hub, then spin it holding the wheelnuts, it's difficult to
turn over. Mind you, maybe that's not enough to prevent the weight of the
rider falling over too.

That's the gyroscopic effect. If the wheel is rotating and you twist the
axle side-to-side (in a horizontal plane), there is a force that tries to
twist the axle up-and-down (in a vertical plane). It acts so as to correct a
tendency to fall over: if you start to lean to the left and the front axle
turns to the left, the gyroscopic force acts to try to move the bike back to
vertical, and its magnitude varies with speed.

I can see why people though that this was the only force that mattered,
since it does play a small part in keeping balance - it's just that it's not
enough on it own.


I would have said a large part. Just try balancing on a bicycle that's stationary.

Quote:
I read of an experiment where a bike was fitted with wheels that had discs
of equal mass to the wheel that were rotated (electrically) in the opposite
direction so as to cancel out any gyroscopic force. And the bike was still
rideable, though it was slightly harder to keep one's balance.


I guess it's also harder if you have a very lightweight racing bike with lighter wheels. Mind you, I could never ride a bike with narrow handlebars, I can only ride mountain bikes. Not enough leverage to balance by steering in those drop handlebar types.

Commander Kinsey
Guest

Mon Jan 28, 2019 9:45 pm   



On Fri, 25 Jan 2019 09:34:50 -0000, NY <me_at_privacy.net> wrote:

Quote:
"Commander Kinsey" <CFKinsey_at_military.org.jp> wrote in message
news:op.zv490lwywdg98l_at_desktop-ga2mpl8.lan...

I knew steering played a big part (I thought about 50%) because I've seen
a trick played where people are given bicycles with fixed steering, and
it's very difficult to balance on them.

Also there have been tests where a perfectly balanced human-size/weight
dummy is attached to a bike, and it falls over even when it is travelling at
a speed that a human could ride easily. That suggests that minute
adjustments to balance and steering are a major factor in staying upright.


I'm sure the wheels play a big part too - if you remove a bicycle wheel
and keep the hub, then spin it holding the wheelnuts, it's difficult to
turn over. Mind you, maybe that's not enough to prevent the weight of the
rider falling over too.

That's the gyroscopic effect. If the wheel is rotating and you twist the
axle side-to-side (in a horizontal plane), there is a force that tries to
twist the axle up-and-down (in a vertical plane). It acts so as to correct a
tendency to fall over: if you start to lean to the left and the front axle
turns to the left, the gyroscopic force acts to try to move the bike back to
vertical, and its magnitude varies with speed.


There's something you can do with a computer chair (as in one that can rotate) and a bicycle wheel. I can't remember what it was, something like your friend gets the wheel spinning and hands it to you, then you turn it to the horizontal, making the chair spin round.

Quote:
I can see why people though that this was the only force that mattered,
since it does play a small part in keeping balance - it's just that it's not
enough on it own.

I read of an experiment where a bike was fitted with wheels that had discs
of equal mass to the wheel that were rotated (electrically) in the opposite
direction so as to cancel out any gyroscopic force. And the bike was still
rideable, though it was slightly harder to keep one's balance.


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