Segway Idle Sound

[buzzert]

Hey everyone!

I was just curious if anyone knows what it is that makes the idle sound (kind of like a fish tank) on a Segway? From careful observation, it appears to be coming from the gearboxes. It's also worth noting that the sound goes away in security mode. What could this be? The segway surely doesn't have an air cooling system (because the power base is water-tight), and it couldn't be the motors moving rapidly to balance the user, as it makes the sound in standby mode as well.

Hmmm

[Mons1]

Hello do you have a gen 1 seg?
Mine is gen 1 and it sonds like yours, Im told this is the
electronic and gyros ho make this sound!

[segsurfer]

I believe the idling sound you hear in both gen one and two is caused by the gyroscopes...the gyroscopes serve as sensors in the balancing procedure, they aren't activated when the seg isn't in any type of balance modes (IE, security mode) As for the high pitched whine that certain people hear, that is a feature on the gen 2's that was purposefully added to alert blind and deaf people to the presence of a segway, apparently they can sense the frequency emitted by the segway.
hope this helps,
-segsurfer

[Neelix]

Are we talking about the FET (field-effect transistor) noise?

The "running water" sound?

I'm pretty sure that is not the gyros. As far as I know they don't make any noise.

[quade]

I'm pretty sure that is not the gyros. As far as I know they don't make any noise.

Well, none that could be heard by human ears.

Pretty much the only thing the noise could be is the motors.

[cruiter]

Neelix you are correct !!! The sound is not the gyros. They are completly solid state (no rotating wheels). Other than the LSF, Gears, wheels, and motors, there are no other moving parts in the i2. It is electronic noise generated from inside basicly just to let you know it's on. The whine when gliding is the gear whine and sometimes when very slow or balancing you may hear gear teeth chatter. All very normal. If I hear noise, I'm re-assured it's running (just in case my eyes are closed :)). There are many posts from a year or so ago with same information. But it's all good.

Come to Atlanta Stone Mountain area for our seg glide on 27 July. Will be a great time and lots of photo opps with the big rock and for those that can spend the night, a great laser light show and music.
Are we talking about the FET (field-effect transistor) noise?

The "running water" sound?

I'm pretty sure that is not the gyros. As far as I know they don't make any noise.

[wwhopper]

And they are very quiet, but it was decided early on they had to make some noise.

So any noise you hear is programmed and does come via the motors.

I bet that noise you are hearing is the noise that was planned so the Segway is not dead quiet.

When you glide, you can hear the gears whine a bit, but it does make that sweeping sound while it is standing still.

Thes sort of sound what you would expect a hovercraft would make in hover mode!

[Gihgehls]

The sound you hear is white noise being mixed into the motor control signal. The purpose of this noise is to cover up the high pitched whines and squeals that electric motors make. Think of a drill motor with the trigger barely pressed down-- It makes a lot of noise.

[scotty1024]

As for the high pitched whine that certain people hear, that is a feature on the gen 2's that was purposefully added to alert blind and deaf people to the presence of a segway

Wonderful! I was starting to wonder if I needed to take it in and have it looked at. To me it sounds like the fusion reactors on the Starship Enterprise: The Next Generation.

I say that and everyone thinks I'm hearing things.

And yes: I'm legally blind, so it works. Especially when you're standing on it. In which case you're wondering if there is anyway to turn it off. :D

[Gihgehls]

As for the high pitched whine that certain people hear, that is a feature on the gen 2's that was purposefully added to alert blind and deaf people to the presence of a segway, apparently they can sense the frequency emitted by the segway.
hope this helps,
-segsurfer

That doesn't make any sense. I think someone lied to you. First, gen1 and gen2 motors and main electronics are identical; the only new sound-related feature on gen2 is that all the sounds are made by the motors. Second, Segway's engineers wouldn't add a safety feature that only "certain people" could hear, at the top of the range of human hearing. Not all blind people have superman ears. I am 25 years old and have excellent hearing, and must struggle to hear the high pitched whine of the motors. Lastly, how could a sound so difficult to hear be useful to deaf people? Sorry, Segsurfer, but this doesn't make sense at all.

Edit: we may have been talking about different things here. Are you talking about the noisy "running water" sound, or are you talking about the high-pitched squeals that sound like a busted television?

[segsurfer]

That doesn't make any sense. I think someone lied to you. First, gen1 and gen2 motors and main electronics are identical; the only new sound-related feature on gen2 is that all the sounds are made by the motors. Second, Segway's engineers wouldn't add a safety feature that only "certain people" could hear, at the top of the range of human hearing. Not all blind people have superman ears. I am 25 years old and have excellent hearing, and must struggle to hear the high pitched whine of the motors. Lastly, how could a sound so difficult to hear be useful to deaf people? Sorry, Segsurfer, but this doesn't make sense at all.

Edit: we may have been talking about different things here. Are you talking about the noisy "running water" sound, or are you talking about the high-pitched squeals that sound like a busted television?

I'm talking about the high pitched frequency that certain people can hear audibly. It sounds kind of like the sonic security systems in jewelry stores. It was purposefully created to alert people, specifically the blind, to the segways presence. I'm taking this from what my dealer said. While most people can barely hear it, such as yourself, that specific frequency is just enough to alert people to the segway's presence.
-segsurfer

[Five-Flags]

...
I'm taking this from what my dealer said.
...
-segsurfer

You know, I've got this bridge in Brooklyn that I'm not using since I moved to Florida.....

I can give you a really good deal on it....:D:D:D:D

[bentbiker]

I'm talking about the high pitched frequency that certain people can hear audibly. It sounds kind of like the sonic security systems in jewelry stores. It was purposefully created to alert people, specifically the blind, to the segways presence. I'm taking this from what my dealer said. While most people can barely hear it, such as yourself, that specific frequency is just enough to alert people to the segway's presence.
-segsurferI think your dealer has misinterpreted what has been claimed by INC. I don't believe they have ever claimed that high frequency is intentional. They have claimed that the motor noises have been "tuned" to alert all pedestrians of the units' presence.

As for that claim, I have my own suspicions. I'd bet the spin meeting went something like this:
Engineer: Well we've tried everything we know how to do to eliminate all sounds from "It", but no matter what we do, there are some sounds that are just the nature or the package -- there is nothing we can do.

Manager: OK. Then lets change gears. This is not "defect", "side-effect", or "nagging-annoyance", it is a "FEATURE" that we purposely added to the unit so that "It" doesn't sneak up on anybody and scare them. Tune it as best you can to the least annoying frequency, but quit spending money to quiet it down; go forth and sell this feature to the naive populace.

[GlennO]

A feature - ? So somewhere in the bowels of our machines there is a speaker of sorts?

Wow, would I like to mod that! This is almost like saying that it has a built-in horn that we should be able to crank up a bit when approaching people, or crank up a lot more for those not paying attention. the possibilities are endless! :)

Glenn

[bentbiker]

A feature - ? So somewhere in the bowels of our machines there is a speaker of sorts?

INC has long claimed that they intentionally made the Segway noisy (my word) by using very complicated frequency calculations to make the motors create the sounds instead of putting a speaker in the unit. You've never heard these claims?

[GlennO]

No, because the gen 1's were a lot quieter than the i2's. As it stands now though, this 'sound' can only be heard if it is quiet outside. If there is sufficient traffic that noise will easily drown it out.

It would be easier to create an electronic sound rather than to re-calibrate any actual working parts. I would consider any machine with a motor that didn't make any noise at all to be better calibrated than one that does.

I haven't done this, but if it is a sound that is created by the working parts then the frequency and/or volume should change as the speed is increased - after all, if you are gliding along at top speed this 'sound' should be able to be heard farther away, and I don't think this is true, but then again my ears today are not as good as they once were.

Glenn

[thouston]

Are we talking about the FET (field-effect transistor) noise?

The "running water" sound?

I'm pretty sure that is not the gyros. As far as I know they don't make any noise.

FET's make noise? I don't think so. They are solid state devices.

I noticed a super high pitched sound coming out of the battery pack yesterday when I had my i2 turned on its side putting air in the tires.

[buzzert]

Yes, it's definitely not the gyros, as they are now accelerometers and do not have any moving parts. I have a gen2 BTW, but I've heard the same sound on the gen1's as well (the sound I'm referring to is the "running water" sound).

Another interesting observation is that the sound appears to get louder when going up a steep surface (like a rounded curb).

The sound you hear is white noise being mixed into the motor control signal. The purpose of this noise is to cover up the high pitched whines and squeals that electric motors make. Think of a drill motor with the trigger barely pressed down-- It makes a lot of noise.

That is fascinating! But what device creates the white noise? The motors? (like for the stick shake and rest of the sounds?)

[Neelix]

FET's make noise? I don't think so. They are solid state devices.

I noticed a super high pitched sound coming out of the battery pack yesterday when I had my i2 turned on its side putting air in the tires.


I love how, every time this thread topic comes up, someone says, "Solid state devices can't make noise."

My rebuttal each time is, "Have you not heard capacitors charge?" Also, you yourself state that you heard a sound coming from the battery; since the batteries don't have any moving parts how is that....

We were told, years and years ago, that the running water noise originates in the FETs. Other noises like tones and beeps (save the noises that come from the handlebar speaker in the gen1) come from the motors via complex signal modulation. I've heard segways play the jeopardy theme, entirely through the motors.

[jgbackes]

I wish they would put the jetson sound back in the motors. Burb, burb, burb.... Would be very cool...

[pam]

Neelix, did you hear the jeopardy theme from INC machines? Those engineers will do incredible things, just having fun. Maybe they'll bring one to fest. I'd love to hear it. BTW, are you and your family coming to fest?
Pam

[Neelix]

Yeah, Pam, I'm surprised you didn't hear it. This was at the Florida Fest.

We'll be in Indiana.

[thouston]

I love how, every time this thread topic comes up, someone says, "Solid state devices can't make noise."

My rebuttal each time is, "Have you not heard capacitors charge?" Also, you yourself state that you heard a sound coming from the battery; since the batteries don't have any moving parts how is that....

We were told, years and years ago, that the running water noise originates in the FETs. Other noises like tones and beeps (save the noises that come from the handlebar speaker in the gen1) come from the motors via complex signal modulation. I've heard segways play the jeopardy theme, entirely through the motors.

No, I've never heard capacitors charge and capacitors aren't solid state devices. Last time I checked there wasn't any silicon crystals inside of a capacitor like in FETs, IC's and microprocessors. What I have heard is the high voltage charging circuit in my old camera charging the capacitor to drive the flash. That charging circuit uses a transformer (Not a solid state device) that makes noise when it's outputting voltage to charge the capacitor to fire the Xenon flash tube.

The noise I heard in the battery pack and the "complex signal modulation" was undoubtedly the PWM power supply (switcher) used in the Segway. The motors in the Segway are brushless neodymium stepper motors made by danaher/kollmorgen. You ever notice how the device cogs at low speed? I have. It's a stepper motor driven by a PWM power supply. PWM power supplies make noise. High pitched noises as a matter of fact. I've read other threads where other users are discussing the high pitched noises coming from their Segways and it's got to be the switcher people are hearing.

Which mode are the FET's in the Segway running? Analog or switching mode?

I strongly suspect they are running in analog mode. I'm not positive but I do have lots of experience with FET's (See US patent #5,993,356). 10 years of R&D to find the right FET's to work in my invention. In that 10 years I NEVER once heard FETs make a peep running in analog mode. I've over powered and burned out plenty of them but never heard a single sound out of them. I'm using a similar neodymium DC motor made by Danaher/Kollmorgen in my invention that's also used in the Segway. I make voltage adjustments to the motor (using a switching power supply) every 5 ms which is also similar to the Segway. In my configuration the motor makes no noise and the FET's don't either. The PWM power supply does make noise depending on how it's being driven.

As far as the Segway motors making music, I guess anything is possible. We all know that vibrations cause sounds to be emitted. My question is which parts inside of the danaher stepper motor used in the Segway vibrate to make noise? Was it the PWM power supply pulse width changes that were making the music/sounds? And if there is noise that's not the PWM power supply then there must be vibration caused by power being applied to the motors. If this is the case, why doesn't the HT take off during music/sound mode and where is the power dissipation occurring? The display showing the jeopardy theme music being played, was it loud? What was vibrating and generating the sound? Does anyone have a link to a video showing the musical Segway they could share?

The old saying: "Don't believe anything you hear and only 50% of what you read". I will add, even if you hear it from INC.

[Gihgehls]

The segway doesn't take off because in order to make sound, a speaker (or motor) needs to vibrate to make sound. That is, it needs to replicate a wave form, and as we all know, waves go up and then down, peaks and valleys. The segway doesn't take off because the motor is vibrating back and forth extremely quickly, and the amplitude of the wave it is recreating is lower than what it would need to be in order to engage the teeth in the gear box. And that low speed rattle-- you've only got it half right. Yes, the motors are steppers, but the noise is a result of rapidly changing torque direction coupled with the gear lash in the transmissions. If there were no gears you wouldn't hear a thing.

[Neelix]

We don't need a video to see a demonstration of the same technique used to play the jeopardy theme. Just turn your segway on. If it's a Gen1 (with the most recent software), it'll give a three tone beep out of the motors, and if it's a gen2, it'll do the warp-engine noise.

[bentbiker]

We don't need a video to see a demonstration of the same technique used to play the jeopardy theme. Just turn your segway on. If it's a Gen1 (with the most recent software), it'll give a three tone beep out of the motors, and if it's a gen2, it'll do the warp-engine noise.Chris,
That is an excellent point. Since these sounds are generated before the unit is put into balance mode, that would seem to eliminate the gears as playing any part in the sounds that are "intentionally" generated. Until such time as balance mode is initiated, the gears are not subject to any torque.

[thouston]

The segway doesn't take off because in order to make sound, a speaker (or motor) needs to vibrate to make sound. That is, it needs to replicate a wave form, and as we all know, waves go up and then down, peaks and valleys. The segway doesn't take off because the motor is vibrating back and forth extremely quickly, and the amplitude of the wave it is recreating is lower than what it would need to be in order to engage the teeth in the gear box. And that low speed rattle-- you've only got it half right. Yes, the motors are steppers, but the noise is a result of rapidly changing torque direction coupled with the gear lash in the transmissions. If there were no gears you wouldn't hear a thing.

You're still at 60k ft. throwing out guesses as to the process involved to make a Segway produce sounds from the motor. Show me someone else other than INC that is doing this. I'm also well aware of how the process might work but if you read between the lines what I'm really asking is WHY. Why would Segway engineer a product that has a switching power supply drive a stepper motor in a way that exercises the stepper just to make some sounds? What about wear and tear? Stepper motors aren't designed to make noise. They aren't speakers they are motors.

Yes, the transmission is making noise at low speeds. I'm only making a point that the cogging felt has nothing to do with the transmission it's strictly a function of the way a stepper motor works.

[thouston]

We don't need a video to see a demonstration of the same technique used to play the jeopardy theme. Just turn your segway on. If it's a Gen1 (with the most recent software), it'll give a three tone beep out of the motors, and if it's a gen2, it'll do the warp-engine noise.

You may not but I really do. I would bet that the demonstration you saw at Fest was some rigged up demo provided by the INC engineering team for nothing more than a "look what we are able to do" as a byproduct of the stepper/switcher combination used. What I really want to know is why would they do it? Don't be so sure in life until you understand all of the pieces that go into what you think you saw or heard.

[glen_d]

In my configuration the motor makes no noise and the FET's don't either.

I suspect that beligerent comments will leave you in the same position as when you started . . . ignorant of how the Segway works. A polite request for information might get you somewhere. Sure, you'll get some mis-information along the way, but I'm sure you can sort that out. But berating people because you think they're stupid or you think you are so much smarter will have just one effect . . . it'll make this place not very much fun to visit for you or anyone else.

Glen

[thouston]

I suspect that beligerent comments will leave you in the same position as when you started . . . ignorant of how the Segway works. A polite request for information might get you somewhere. Sure, you'll get some mis-information along the way, but I'm sure you can sort that out. But berating people because you think they're stupid or you think you are so much smarter will have just one effect . . . it'll make this place not very much fun to visit for you or anyone else.

Glen

First, Neelix started by stating "I love how, every time this thread topic comes up, someone says, "Solid state devices can't make noise." Does that sound friendly to you? Sounded belittling to me and just because I've got 14 posts and Neelix has 1K doesn't make me a neophyte. He assumed I was and I responded appropriately proving him wrong.

Secondly, did I say I was smarter than anyone else? This stuff excites me and I have a great desire to know more and spirited conversation is how things get done and people learn new things. Yes, I have experience in some areas beyond the average and I'm sorry if you are threatened by this and perceive it as a boast. Being Segway owners, I'm almost positive that most folks on this board have extensive knowledge in areas that I can't even fathom.

[rrc1962]

The motors in the Segway are brushless neodymium stepper motors made by danaher/kollmorgen. You ever notice how the device cogs at low speed? I have. It's a stepper motor driven by a PWM power supply. PWM power supplies make noise.

Are sure of that? I'm not arguing because I don't know for sure, but I'd be real surprised if Segway was using stepper technology. That is old technology. Servo drivers make the same high pitched sounds. I've built many CNC machines using both stepper motors and servo motors. Steppers are cheaper to implement, but servos deliver vastly superior performance.

[jgbackes]

Tom,

Try this, take the cover off a gen 1 segway (I have, see my water posting on the WIKI) and power the machine up and down, there is audio (generated by the motors) coming from the base unit. This is not magic or trickery, it's just a wave being sent to the motor controllers that is being "played" by the motors.

There is a video showing the engineers that worked on the controller board. As he holds it up he says, "See, no speaker." I think the engineers there are very proud of the fact they have taught the Segway to make noise without having to add a speaker.

My guess is that the elastomer connection from the wheel through the transmission allows them a little latitude in motion. They can command the unit to move VERY small distances and not actually cause the tires/wheels to spin.

The gear ratio in the transmission is 25 to 1, as I recall, so moving the motor one step in either direction is not going to effect the motion of the base unit.

If you could, on your invention, try this and let me know how it work... Command the stepper to move forward, then backward one step at 440 times a second. Do you get any sound? Should be an middle C if my theory is correct. Perhaps I'll do a patent search and see if anyone has a patent on using a stepper motor in such a way to make UI noises.

Keep inventing, the world needs cool new toys!

[thouston]

Are sure of that? I'm not arguing because I don't know for sure, but I'd be real surprised if Segway was using stepper technology. That is old technology. Servo drivers make the same high pitched sounds. I've built many CNC machines using both stepper motors and servo motors. Steppers are cheaper to implement, but servos deliver vastly superior performance.

No, I'm not sure. I only have experience with the N series ServoDisc line of Danaher motors. www.electromate.com/db_support/downloads/KollmorgenNseries.pdf They aren't brushless and are in a different configuration than the ones used in the Seg. I had read somewhere that the Seg motor was brushless. That with the fact that I can feel it cogging helped me to make the statement that they are steppers. I would really love to know the exact Danaher motor used. It would tell us a whole lot more about the drive mechanism.

[Mr5150]

My dealer said it was fan noise like a PC? Hmmm....

[thouston]

Tom,

Try this, take the cover off a gen 1 segway (I have, see my water posting on the WIKI) and power the machine up and down, there is audio (generated by the motors) coming from the base unit. This is not magic or trickery, it's just a wave being sent to the motor controllers that is being "played" by the motors.

There is a video showing the engineers that worked on the controller board. As he holds it up he says, "See, no speaker." I think the engineers there are very proud of the fact they have taught the Segway to make noise without having to add a speaker.

My guess is that the elastomer connection from the wheel through the transmission allows them a little latitude in motion. They can command the unit to move VERY small distances and not actually cause the tires/wheels to spin.

The gear ratio in the transmission is 25 to 1, as I recall, so moving the motor one step in either direction is not going to effect the motion of the base unit.

If you could, on your invention, try this and let me know how it work... Command the stepper to move forward, then backward one step at 440 times a second. Do you get any sound? Should be an middle C if my theory is correct. Perhaps I'll do a patent search and see if anyone has a patent on using a stepper motor in such a way to make UI noises.

Keep inventing, the world needs cool new toys!

It's funny you would post this. I am VERY close to disassembling my i2 to get in there and figure some of this stuff out. I have a feeling that this would void my warranty. I've go some other steppers available and I'll have to setup a test with your suggestion.

Very informative post. Thanks for posting.

[Gihgehls]

Show me someone else other than INC that is doing this.

http://www.afrotechmods.com/cheap/hdspeakers/hdspeakers.htm

[segsurfer]

Tom,

Try this, take the cover off a gen 1 segway (I have, see my water posting on the WIKI) and power the machine up and down, there is audio (generated by the motors) coming from the base unit. This is not magic or trickery, it's just a wave being sent to the motor controllers that is being "played" by the motors.

There is a video showing the engineers that worked on the controller board. As he holds it up he says, "See, no speaker." I think the engineers there are very proud of the fact they have taught the Segway to make noise without having to add a speaker.

My guess is that the elastomer connection from the wheel through the transmission allows them a little latitude in motion. They can command the unit to move VERY small distances and not actually cause the tires/wheels to spin.

The gear ratio in the transmission is 25 to 1, as I recall, so moving the motor one step in either direction is not going to effect the motion of the base unit.

If you could, on your invention, try this and let me know how it work... Command the stepper to move forward, then backward one step at 440 times a second. Do you get any sound? Should be an middle C if my theory is correct. Perhaps I'll do a patent search and see if anyone has a patent on using a stepper motor in such a way to make UI noises.

Keep inventing, the world needs cool new toys!

JG, Have you been able to find that video on the internet?
-segsurfer

[LoupGarou]

The sound is coming from the motors, not the gyros. You can hear the gyros, but you need to have a ultrasonic detector/downconverter and have the cover off the baseplate to expose the gyro group to be able to hear them. Something like this:
digitalzeus.wordpress.com/2008/01/06/175

The motors are 3 phase servos, not steppers, and they are controlled with a full three phase FET driver, not just a simple stepping system. This setup is what allows it to do everything from "stick shake" to all of the other warnings and sounds that it does without dropping the torque to the wheels or locking the rotors up. It is also what makes both the regenerative braking, and it's ability to proportionally limit torque and current draw through pulse shaping. You really need to watch the board's output on a good digital storage oscilloscope to get a good appreciation for all of the work that has gone into the design. If you are gliding along on level ground, current consumption drops to next to nothing, even though you are rolling along at a good clip (8-10MPH). As you lean back to brake hard, the spikes are clearly noticeable on the DSO as the unit applies reverse torque.

Very good engineering job Segway.

Loup
(Enjoying my X2 while waiting for the 3rd Gen series, and praying for them to get the Centaur to market)...

[LoupGarou]

The sound is coming from the motors, not the gyros. You can hear the gyros, but you need to have a ultrasonic detector/downconverter and have the cover off the baseplate to expose the gyro group to be able to hear them.

The motors are 3 phase servos, not steppers, and they are controlled with a full three phase FET driver, not just a simple stepping system. This setup is what allows it to do everything from "stick shake" to all of the other warnings and sounds that it does without dropping the torque to the wheels or locking the rotors up. It is also what makes both the regenerative braking, and it's ability to proportionally limit torque and current draw through pulse shaping. You really need to watch the board's output on a good digital storage oscilloscope to get a good appreciation for all of the work that has gone into the design. If you are gliding along on level ground, current consumption drops to next to nothing, even though you are rolling along at a good clip (8-10MPH). As you lean back to brake hard, the spikes are clearly noticeable on the DSO as the unit applies reverse torque.

Very good engineering job Segway.

Loup
(Enjoying my X2 while waiting for the 3rd Gen series, and praying for them to get the Centaur to market)...

[jgbackes]

I can't find it for the life of me... It was a collection of videos some one here with a better memory than I have will hopefully remember.

[Neelix]

One other thing: in an emergency shutdown (on a gen2, at least. I honestly forget how a gen1 behaves in a shutdown...) the louds beeps and the final "scream" that it makes come out of the motors, just like all the other sounds. Sounds won't begin coming out of the motors until after you've dropped below a certain speed; I was led to believe (I'm going to phrase anything I'm not 100% sure of like this so people don't jump down my throat) that this is because there is the possiblity of problems when the music/sound signals are sent to the motors while they're moving at higher speeds.

[buzzert]

One other thing: in an emergency shutdown (on a gen2, at least. I honestly forget how a gen1 behaves in a shutdown...) the louds beeps and the final "scream" that it makes come out of the motors, just like all the other sounds. Sounds won't begin coming out of the motors until after you've dropped below a certain speed; I was led to believe (I'm going to phrase anything I'm not 100% sure of like this so people don't jump down my throat) that this is because there is the possiblity of problems when the music/sound signals are sent to the motors while they're moving at higher speeds.

You are right, it'll give you severe speed limiter until sounds finally start playing.

Here's a video!: http://youtube.com/watch?v=f7GQ3LaqhpM'

I think it's intriguing that the segway is able to make those very loud sounds and still manage to produce the sub-audible stick-shake at the same time; because remember, any sound that comes out of the motors is actually just a really high-frequency stick-shake.

[Neelix]

Are sure of that? I'm not arguing because I don't know for sure, but I'd be real surprised if Segway was using stepper technology. That is old technology. Servo drivers make the same high pitched sounds. I've built many CNC machines using both stepper motors and servo motors. Steppers are cheaper to implement, but servos deliver vastly superior performance.
You're right, Ross. This time I have a citation. In the book "Segway Secrets" (2003) pg 3-8, it reads, "[the motor]...is a servo motor, meaning it's smart and will do whatever it is told to." Also, Amazon.com's Segway technical specifications page reads, "Motors: Two brushless, DC servomotors."

[thouston]

http://www.afrotechmods.com/cheap/hdspeakers/hdspeakers.htm

This is an interesting project but not quite what the Segway is doing. IF it's doing what folks on the board are saying it's doing...

[Gihgehls]

Thouston, please explain to me the difference between a speaker and an electric motor.

[thouston]

Thouston, please explain to me the difference between a speaker and an electric motor.

I'm really not sure. Why don't you explain it to me?

[Gihgehls]

I'm really not sure, but one of them uses magnets to convert electrical signals into physical motion, and the other one uses magnets to convert electrical signals into more pronounced physical motion.