Dynamic Stabilization Myth, Fact and Phys. (dead)

[4Seg]

dead thread.

[JohnG]

Um, if the Segway weighs 80 lbs. and the person on it weighs 200 lbs., wouldn't you also have to take into account the person who's standing on the Segway and where their center of gravity is (much higher and above the axle)? I would think so.

[charmed]

Excellent points, 4Seg. It should be noted, however, that with the DS in the iBot, the weight is well above the axle(s). No doubt getting the weight below the axle makes it much easier for the Segway to keep a person upright. I wonder, though, exactly how easy it would be to balance on it without power....I get your point, and I agree with it, but it would be a pretty shaky pendulum, I think.


Somewhere I read that in the case of the iBot, or applications where the weight is above the axle, the further away the weight is the easier it is to stabilize it (as in balancing a stick on your palm- the longer the stick, the slower the reflexes required to move under it).

Fascinating stuff. I hope you get your reseller's license soon, I'm ready to buy.

[ftropea]

4Segway,

I like Kamen's "balancing a broomstick on your hand by the end of its handle" example better ;)

Especially if we're talking DS!

But I understand your point. However, I think the "magic" is that it only takes little subtle movements beneath your feet to keep you balanced.


Regards,

Frank A. Tropea
----------------------------------
Ginger : Robotics :: PC : Computers

[4Seg]

quote:Originally posted by jgrohol


Um, if the Segway weighs 80 lbs. and the person on it weighs 200 lbs., wouldn't you also have to take into account the person who's standing on the Segway and where their center of gravity is (much higher and above the axle)? I would think so.

You're exactly right; however, keep in mind most of the weight is in the wheels and the platform and the platform also sets below the axles. True the center of gravity is truly about the mid section a person's body; however, the focal point of weight is concentrated below the axle. When a Segwayist leans forward the CG is shifted thus causing a delta in pitch to the platform. DS detects this and
attempts to regain pitch. (This is DK's controlled fall he fondly talks about).

If we could only be resellers...

[4Seg]

quote: However, I think the "magic" is that it only takes little subtle movements beneath your feet to keep you balanced.

True, however, not true about a Segway at a standstill.
The machine can be off you will naturally be balanced. Of course, if you lean forward with it off (and the kickstand isn't down) you will fall forward flat on your can.

Oh, this too, your feet dont move a bit. Other people who have ridden the Segway mention a slight bending of the knees. Very true for standing in one spot. No stiff legging! ;)


If we could only be resellers...

[4Seg]

quote:Originally posted by charmed

Excellent points, 4Seg. It should be noted, however, that with the DS in the iBot, the weight is well above the axle(s). No doubt getting the weight below the axle makes it much easier for the Segway to keep a person upright. I wonder, though, exactly how easy it would be to balance on it without power....I get your point, and I agree with it, but it would be a pretty shaky pendulum, I think.


Somewhere I read that in the case of the iBot, or applications where the weight is above the axle, the further away the weight is the easier it is to stabilize it (as in balancing a stick on your palm- the longer the stick, the slower the reflexes required to move under it).

Fascinating stuff. I hope you get your reseller's license soon, I'm ready to buy.


Thanks Charmed. I think we will find the i-Bot probably weighs a lot more than it looks. Have you ever seen someone ride a unicycle? LOL I use to actually. The wheel is constantly moving to be able to "appear" to stay in one spot. That is not the case with the Segway nor the i-Bot (they are both completely still) I think we will find that every day science plays a major role instead of DS. The iBot has a much more to it. A handicapped person won't be able to lean. I haven't spent much time researching more.

I will say that the hidden DS is simply good placement of the platform.



If we could only be resellers...

[don c.]

Hanging the weight of the passenger platform from the axle gains the Segway some balance benefits, but not nearly enough to switch off the DS and hope to remain upright. The wheels of the Segway don't make the obvious, wide, back and forth swing as human piloted unicycles, because the MEMs gyro sensors and the DSP's can react to an out of balance situation much more rapidly than a human. That doesn't mean the wheels aren't undergoing torque or movement though, however small. Connect an oscilloscope to the motor power inputs of a Segway and view the heartbeat of DS at a standstill; much like a human heartbeat, but with many of the traces on the screen painted downwards (along with upwards).

http://www.howstuffworks.com/ginger2.htm

"The Segway has five gyroscopic sensors, though it only needs three to detect forward and backward pitch as well as leaning to the left or right (termed "roll"). The extra sensors make the vehicle more reliable. All of the tilt information, as well as information from additional tilt sensors, is passed on to the brain of the vehicle. The brain is made up of two electronic controller circuit boards, comprising a cluster of microprocessors. Time Magazine reports that the Segway has 10 onboard microprocessors, which boast, in total, about three times the power of a typical PC. The vehicle requires this much brain power because it needs to make extremely precise adjustments to keep from falling over. If one board breaks down, the other will take over all functions so that the vehicle stays upright".

[4Seg]

quote:Originally posted by don c.

Hanging the weight of the passenger platform from the axle gains the Segway some balance benefits, but not nearly enough to switch off the DS and hope to remain upright. The wheels of the Segway don't make the obvious, wide, back and forth swing as human piloted unicycles, because the MEMs gyro sensors and the DSP's can react to an out of balance situation much more rapidly than a human. That doesn't mean the wheels aren't undergoing torque or movement though, however small. Connect an oscilloscope to the motor power inputs of a Segway and view the heartbeat of DS at a standstill; much like a human heartbeat, but with many of the traces on the screen painted downwards (along with upwards).

http://www.howstuffworks.com/ginger2.htm

"The Segway has five gyroscopic sensors, though it only needs three to detect forward and backward pitch as well as leaning to the left or right (termed "roll"). The extra sensors make the vehicle more reliable. All of the tilt information, as well as information from additional tilt sensors, is passed on to the brain of the vehicle. The brain is made up of two electronic controller circuit boards, comprising a cluster of microprocessors. Time Magazine reports that the Segway has 10 onboard microprocessors, which boast, in total, about three times the power of a typical PC. The vehicle requires this much brain power because it needs to make extremely precise adjustments to keep from falling over. If one board breaks down, the other will take over all functions so that the vehicle stays upright".
Don, thx. DS probes connected to the o-scope will indicate very slight power consumption when the HT is at rest; however, would you agree we would see slight adjustments? There is no movement when stopped, I witnessed this in person. I was able to observe about 75 or more people ride the Segway at the Chicago show. (Where's Brooster?!!) Brooster had an exclusive showing with Segway, and I happen to be there "in the back room" as well. We were able to ask Eric from Segway very specific questions. (Brooster has a list of questions and answers, see TIQ, there is a few posts about this)

I am still amazed by the stability of the Segway. I was the first one at that show. (6:45 before the Museum opened. Hell, I was even behind the scenes and even ended up in the Marketing Director's office asking questions. it was pretty cool. The people at the Show were great).

I went to the show with mixed emotions and was hoping not to be let down by all the hype. I studied the Segway for almost 4 hours as I saw many people with huge grin on their faces. Richard, an employee at the museum, was the first to ride. A free-lance journalist was also there to interview him after he had his experience. Richard can affirm the smooth ride. CJ compared it to flying (I suppose it was the reason he took the goggles. )

Eric said he also rode the Segway down stairs! LOL. I imagine we'll have X-Treme Segway matches in the future. LOL.

Just some rambling thoughts and remembering the ride.



If we could only be resellers...

See the Segway clips! http://www.stlsegway.com/movies

[Dreamer]

The movie clips are informative.

The one thing that bugs me is the girl that follows the rider around, as if something catastrophic might happen. If the Segway HT is safe to ride, the presence of the girl is sending the wrong message.

I didn't notice any of the riders having any difficulty learning how to control the Segway. Oh, I understand the liability issues, but the presence of the girl helper in the video is just plain silly, and it detracts from the demonstration of how easy it is to learn how to ride a Segway.

I'm done with my rant. Carry on.

[4Seg]

quote:Originally posted by Dreamer

The movie clips are informative.

The one thing that bugs me is the girl that follows the rider around, as if something catastrophic might happen. If the Segway HT is safe to ride, the presence of the girl is sending the wrong message.

I didn't notice any of the riders having any difficulty learning how to control the Segway. Oh, I understand the liability issues, but the presence of the girl helper in the video is just plain silly, and it detracts from the demonstration of how easy it is to learn how to ride a Segway.

I'm done with my rant. Carry on.


I hear that! I think she was there just make people feel comfortable. I will make a point of that on the site. Thanks! (I just wished she would have gotten out of my way! :)

If we could only be resellers...

See the Segway clips! http://www.stlsegway.com/movies

[Casey]

quote:(I just wished she would have gotten out of my way! :)

Probably the reason she was there. Remember how the riders on GMA and the Tonight show kept trying to get a little crazy with it. She was probably a buffer between you taking it easy or getting carried away, spinning doughnuts etc. :)

Frank

[4Seg]

You're probably right. :-)

If we could only be resellers...

See the Segway clips! http://www.stlsegway.com/movies

[Seg-wager]

I can't wait for the spinning donuts part! ;) I've been dreaming about that for hmmmmm, awhile...wheeeeeeeeeeeeee! Yes, if something happens it will be my own fault!

[ftropea]

Hey look... We have a lot of first hand accounts from people trying a Segway-HT for the first time. Many of them say the sensation is strange... something they didn't expect. In fact, many of them feel as if they're "unstable" aboard the Segway-HT, that is until their minds "plug into" the control loops and steady themselves. I don't have a problem with Segway people being there when people are first learning to ride the device. In fact, if they weren't there - there is a chance that *some* of these people might of done something wrong.. panic.. or possibly hurt themselves. So it's for the good of the "first time" - the good of the company - and the good of surrounding spectators - that someone is there to "hold their hands" and guide them through it.

Regards,

Frank A. Tropea

[4Seg]

I couldn't agree more Frank. The girl was extremely polite and even took time out to answer some questions. The only problem was her answers sounded scripted directly from their web page. If you look at the beginning of my ride, I'm pretty shakey. She grabbed the control stick and gave me a quick tip and I was off an running. (or better yet Segg'n) ;)

If we could only be resellers...

See the Segway clips! http://www.stlsegway.com/movies

[Seg-wager]

(True, Frank. Of course I'd actually like to know how to ride one before trying anything fancy and the 'just learning' stage, or a time with others nearby wouldn't seem the appropriate moment to do so.)

[Brooster]

That girl ain't just any girl, BTW.



Brooster

[Turtle]

I'll step in here to say that no, it is not possible to balance on a Segway that's off. I'll explain briefly why.

When the HT is live, it's constantly sensing motion and angle on the platform, and in effect moving it slightly to remain under what it has calculated to be your collective center of gravity. You, as a human being, do this constantly, every instant. I defy anyone to stand... absolutely... still. You can't do it, and neither can the Segway. Sure, it might balance momentarily, but when you, the human, move some part of your body to restablish YOUR momentary balance, a Segway that's off can't then respond to you, which it must.

In short, you'd fall over in seconds unless you did an elaborate wobble to try to stay upright. The fact that about 50 pounds of weight is below the centerline of the axles (the wheels don't count) is irrelevant. In fact, because of the placement of the stick, an "off" Segway can't even balance itself, even though the weight of the stick is less than that of the batteries under it.

The "handler" walking along with guest riders is so they don't go bananas and go off and do something dumb.

[4Seg]

quote:Originally posted by Brooster

That girl ain't just any girl, BTW.

Brooster

Hey Broo! :D Anything we should know? I feel bad I couldn't remember her name. She was VERY nice. She was extremely patient and was helping people all day.

If we could only be resellers...

See the Segway clips! http://www.stlsegway.com/movies

[ftropea]

You know, it may be ideal to have even *less* weight in the base when talking "Dynamic Stabilization." Don't know for sure.. but my gut tells me that reducing the weight/mass in the base creates less work for the motors to do. Of course I'm not suggesting a decrease in power.. it still has to be able to shuffle you around at 12mph.. but getting the weight down in the base, either by using lighter materials.. or lighter, more advanced batteries - should be advantageous to overall performance/efficiency.

Regards,

Frank A. Tropea

[Brooster]

Thanks for the clarification, Turtle.

4Seg, the gal was very nice indeed, and extremely helpful. I don't think it's appropriate to mention her name or position here in the open forum ... let it suffice to say that she's not just one of the "hired handlers." She's a bit higher up in the organization.

Brooster

[4Seg]

quote:Originally posted by Brooster

Thanks for the clarification, Turtle.

4Seg, the gal was very nice indeed, and extremely helpful. I don't think it's appropriate to mention her name or position here in the open forum ... let it suffice to say that she's not just one of the "hired handlers." She's a bit higher up in the organization.

Brooster

Broo, thx. I wasn't suggesting mentioning any names. I thought that you were hinting that she was someone other than a Segway employee. (Perhaps a friend of yours.) that's all.

I'll let a cat out of a bag here I have never mentioned on any forum. From an accident I had almost 18 years ago, I have partial loss of balance. (ironic eh?) It was due to massive head injuries and loss of hearing in the left ear. I went to Chicago, not only to see it in real life; but, to see how I could perform with it. I actually mentioned the balance ordeal to the "Segway Girl" and her reaction was like she was a bit suprised. She also seemed confident I would not have any problems operating the Segway. And as you can nv20e, I was off and flying quickly.

[ftropea]

4Seg...

Thanks for sharing that. Interesting point... How does your sense of balance effect you in daily life? Is riding a bike or conventional scooter out of the question?

Regards,

Frank A. Tropea

[4Seg]

quote:Originally posted by ftropea

4Seg...

Thanks for sharing that. Interesting point... How does your sense of balance effect you in daily life? Is riding a bike or conventional scooter out of the question?

Regards,

Frank A. Tropea

Both could be a problem should I turn my head around to quickly glance behind me (ie to look for traffic). It's quite comical to see me perform that act. See scooters and bikes turn when you lean, the segway won't turn as bad (or next to no turn), the steering grip prevents me from loosing balance. I know mirrors would help on bikes and scooters, but there's always the compulsion to turn around.





If we could only be resellers...

See the Segway clips! http://www.stlsegway.com/movies

[4Seg]

I was just reading through this thread and found few errors. Nothing new in this thread., sorry.

If we could only be resellers...

Mike
http://www.stlsegway.com
Yahoo: stlsegway

[BruceWright]

I don't agree with the theory that the weight below the axel has much to do with stability at all. When you say the "focal point of gravity", where do you get that? Gravity doesn't have a focal point. If the center of the combined mass of you and the device is above the axel, you will fall without motor power. Unless those batteries weigh 200 pounds, and are hanging more than 3 feet below the axel, they are not an effective counter-weight for an average man.

[GlideMaster]

I think Jgrohol responded to this topic in his 17 Sep. 2002 posting and was on the money.

Ok I don't know why I'm getting in this discussion but for the good of the sight I am submitting this information from the Participant Workbook. Hope it helps.

Theory of Operation

Dynamic Stabilization
The Segway HT uses a technology called dynamic stabilization. When you lean forward, the device moves forward. When you lean backward, the device moves backward. The sensations of movement are similar to those that people experience everyday while walking.

Dynamic Stabilization

Statically stable objects avoid tipping by:
keeping a low center of gravity maintaing a wide, stable base
Hummans are unique because, in walking erect:
they carry their center of gravity up high they have a very small footprint

The Segway HT has no throttle or brake controls, and responds to your every move as if it were an extension of your body. You lean forward; Segway detects it with sophisticated sensors, and drives the wheels as needed to keep you upright while moving forward.

Lean back, and Segway slows to a stop. Once stopped, leaning back also allows you to move backwards.

Segway HT can balance in place, allowing you to stan motionless by detecting minute changes in balance and instantly responding. There is no need to leave the Segway HT when stopped.

When commanded, Segway's computers can rotate one wheel forward and one rearward, turning in place.

Lateral (side-side) Stability

Lateral Stability

Dynamic stabilization technology balances the Segway HT forward and backward. The rider must maintain dynamic lateral stability (side-to-side).

There are diagrams in the workbook to go with this information.

<center>REMBER:
Responsible Riders Ride Segway
and
Segway Riders Ride Responsibly

Segway, The Mind Changer</center>