Segway tone generator

[bystander]

Did something a little unusual to my I167.

It's sort of a sound system modification. Many folks have added speakers and whatnot to their HT. I did the same, but instead of playing the radio, or CDs or MP3s, I play the sound of the motors through the sound system.

I found a way to pick up the magnetic leakage from the motors. The sounds are in the audio range and using a pair of inductive coil pickups, it's about at the same audio level as an electric guitar type signal.

I bought an inexpensive ($16) set of amplified stereo speakers and added a small homebuilt audio preamp to bring the level up.

It sounds quite interesting (to me at least). There's some kind of harmonic present and it sounds similar to a ring modulator effect.

The pitch is low at low speed and high at high speed. In a gentle turn at speed, there is a warbling effect.

I didn't put much high frequency filtering in the circuit, so at standstill and very low speed, one can hear some of the PWM driving signal, it's similar to the white noise the HT already makes by itself - but you can turn the volume of the "noise" up and down with the amplified speaker's volume control.

It sort of makes a purring or growling noise at low speed. If you power the HT off, then drag it around with the audio amp left on, you can still hear the tones as you move because the magnets are still turning inside the motors.

One nice thing about this modification is that everything is external to the HT. Nothing is cut or opened. The inductive sensors are just taped under the platform near the motors. There is a sweet spot to pick up the best sound. Some places near the motor have a louder signal, some places have more or less of the harmonic signal.

Here's a picture (http://www.segwaychat.com/photos/bystander/spots.jpg) of where on the chassis I placed the sensors. This photo was originally from Stan Dobrowski's site. I added the red ellipses to show where I placed the pickups. No need to remove the batteries, the picture is from Stan's disassembly photo page.

Stan, I hope you don't mind if I borrowed one of your pictures. I don't have my camera handy right now.

It would be interesting to have several HTs equipped with this kind of sound system and run them all at once.

It might also be interesting to run the motor's audio signals through various guitar pedal effects.

[KSagal]

Bystander,

Let me see if I got this right. You have modified your seg to sound more like a seg.

Maybe your's could sound like an Uber Seg...

I am reminded of an old "Lost in Space" episode where the robot is captured by a whole bunch of little robots and made into their king...

If I go to a segfest with you, will my seg want to run off with your seg? You may be messing with the natural order...

Yuk, Yuk



Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[bystander]

It is the equivalent of clipping playing cards to the fork of a bicycle so when they hit the spokes, a buzzing noise is produced.

It's just a fun effect, an audio embellishment, perhaps comparable to blinking lights or electoluminescent tape.

It doesn't merely amplify the noises of the HT, the harmonic content of the signal almost adds an extra dimension to gliding.

The effect turns out to be better at low and medium speeds. Once traveling steadily over 9 or 10 MPH, it eases into a dull drone.

I don't know how well I can describe the sound. My first post doesn't seem descriptive enough.

This should make a great spooky sound effect for Halloween.

Almost like a sound one would hear in classic arcade games from the 70s and 80s.

I don't know that it would have a pied piper effect on any other segs, or seg riders for that matter. But it does sound interesting.

[KSagal]

It seems to me that this is the seg equivilent of Glass Pacs or straght pipes on your hog...

It doesn't increase the horsepower, it just makes the same sound like more...

I have never been particularly aurlly inclined, but there is clearly a segment of the population that is...

Good luck with this latest project... You should post a small clip with both sound clips (regular and inhanced)

Just be careful. It happened with Harley's. I don't know if you glide with a helmet or not, but if you do, I don't want to see a news report in the future of you with your suped-up sounding seg and the viking horns on your helmet!

I must remove my tounge from my cheek so I can go to work...

Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[bystander]

Well, I am aware this project seems frivolous. I don't mind.

But there's something more here than frivolity. There's an extra measure of feedback going on.

When gliding and balancing, and you shift your weight, the HT pushes back. Push it a little, and it pushes back a little, push it more, it pushes back more. Gliding can be a dialog between you and the vehicle.

When gliding with the amplified motor audio, there's an instantaneous sense of how much the HT is "pushing back" to keep you balanced. Perhaps I am overstating the effect, but an additional channel of communication seems to be occurring.

I probably could scrape together a recording (but I'd have to work out a means of hosting it). The sound by itself may be interesting to some. But without the context of what the HT is doing while it is making that particular sound, most would only find it a curiosity.

It's more of an interactive thing.

[KSagal]

I know I am poking fun at you but this is interesting. Kind of a biofeedback for your seg.

You must remember that I am a very conservative fellow, and may not put the same value on a biofeedback device as someone else (I'll refrain from saying someone from California...)

I actually do applaud this effort to bring the communication between rider and device to a higher level. It really is a good thing...

I am somewhat of an accomplished troubleshooter in my little field of engineering types... I have encountered very few problems that I could not find and repair, on the commercial equipment that I deal with. When I arrive as the factory rep or as the back-up engineer and find the problem that has eluded the on site folks for a while, they often ask how I find things that often are not in the documentation or the circuit prints.

I almost always tell them it is because I can position myself to be able to communicate with almost anything... I can understand what the machine is trying to do, and why it is trying to do it, and what would stop it from getting it done...

It sounds as weird as your original posts... I hope there aren't some boobs like me just waiting to give me a hard time as I did you...

Anyway, Good luck with your efforts, and I am looking forward to hearing about future ones.

Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[W9GFO]

quote:I have found very few problems that I could not find...

You should make that your sig.

[KSagal]

Well corrected, I meant to say that I have found very few machine faults that I could not find the cause to, and therefore repair...

I deserved at least that much, considering how much I busted Bystander's chops, especially since I basically agree with him...

Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[yosgof]

Bystander,

Could you record the sound (a small sample) and post a link for the rest of us to hear and appreciate?

- Yossi
http://gallery.photo.net/photo/3365119-lg.jpg

[Doug Field]

OK, this ranks as one of the coolest Segway hacks ever.

MP3's or WAV's, please!!

Doug

"There is nothing more difficult to take in hand, or more perilous to conduct, or more uncertain in its outcome, than to take the lead in the introduction of a new order of things." -Niccolo Machiavelli

[pam]

Love it.
Pam

[bystander]

O.K., I borrowed someone's iTalk and made a short recording while riding around at various speeds with lots of stops and starts on a fairly smooth, painted concrete surface.

I have no problem posting a link, but I don't have a way to host a file. The Segwaychat interface only seems to be able to upload image files. (I tried renaming a file, just in case, but it apparently checks the file's contents) Anyway, the file I've got is way too large.

I'm not sure converting it to MP3 to make it smaller is a good idea. The recording is slightly overmodulated and it's already at a low rate. Turning it into a MP3 might make artifacts that would be confusing. I'm sure most listeners will find the sound quite chaotic as it already is.

I am currently looking into ways of getting the recording posted. The file is around 1.9MB and is one minute, 58 seconds long. WAV format, Mono, 8 kHz rate. Compressed into a .zip file, it's still 1.63MB.

If there are any volunteers willing to host this, I am willing to email you the recording. Please contact me through my profile here on Segwaychat.

Edited for P.S.

P.S. I've converted it to MP3 without it sounding too much different from the WAV. It's now at 350 KB.

[bystander]

Thanks to groundloop's help, here are links to the recording I made earlier.

http://www.trix.com/GroundLoop/bystander.mp3 (349 KB)
http://www.trix.com/GroundLoop/bystander.wav (1.9MB)

Warning: parts of this are loud. Turn your speakers down a little the first playback, then turn them up later to listen for the details.

The staticy noise at the beginning is the HT at a standstill, with the volume turned all the way up. It starts growling and rumbling as it starts moving and turning slowly. I step on the platform at around the 3 second mark.

At around 7 seconds, I accelerate for a few seconds then stop. I make several starts and stops, turning, going forwards and backwards up to around the 45 second mark.

Between 47 and 50 seconds, I accelerate backwards hard enough to cause reverse stick shake, you can probably hear it.

Between 50 and 72 seconds, I make two approx. 10-11 second longer runs. At around 72 seconds I slow down to a standstill. That thumping and rumbling noise is from the speakers, it's not me running into anything - but it sure sounds like collisions. When the HT is moving very slow, there is a lot of low frequency present from this setup.

At around 78 seconds, I dismount and power off the HT. If you turn the volume up, you should hear blinky going to sleep. The rest of the sounds are me pushing the HT along. The magnets turning in the motors continue to generate their signals which are amplified by the speakers.

I make about 3 bursts of speed pushing, then maneuver the HT around at a low speed until the recording ends. When pushing, there's a little less of that staticy background noise because the PWM signals are not present, since the HT is off at that point.

There's about 4 things going on at once. Each motor has a fundamental waveform, plus harmonics riding on the fundamental. There are two pick-ups, one side to each stereo speaker. I can hear the fundamental, the zero-beat between the two slightly different frequencies from each motor, and the harmonics.

The sound at times reminds me of the "thick" bonus multiplier sound heard on some Atari arcade games such as Tempest or I, Robot.

Thank you groundloop for helping with this.

[macgeek]

Sounds like a alien harley!
I LOVE IT!!!!!!!


Jonathan

"Think outside the car"

[pam]

Neat harmonics with the undergrowl and the clicks.
Thanks, Bystander.
Pam

[Sal]

Agreed, this is very cool.

-Sal

Think Different
www.apple.com

[KSagal]

After listening, I have to say that there is no question who's seg sounds like the king...

It's back to that 'Lost in Space' episode. I have no doubt that my seg would consider your seg it's leader!

Very cool, man. Keep this stuff comming...


Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[Zorba9]

"Hello? Segway tech support? Can you help me? My HT has started making the strangest growling noises, I'll let you hear this................." :)

KOG

Zorba9.....

[Brooster]

Man, in the first few seconds there, I thought I was listening to one of these!

http://www.ww2racing.com/Pomona2003/burnout-night.jpg

Neat stuff!

[8][:P]

Brooster

[yosgof]

Vety nice indeed.

More like an alien Honda.

Now just outfit your HT with a mean boom box (and lots of chrome), patch it through and...

- Yossi
http://gallery.photo.net/photo/3365119-lg.jpg

[terryp]

That would sure get my attention if it was coming up behind me on the sidewalk. Pretty cool.

Segway - What's holding you up?

[Sal]

As some of the above have said, add some chrome...

...a sidecar, shave your head, go topless with a leather vest, and you have a very hi-tech Hell's Angel.

-Sal

Think Different
www.apple.com

[JD]

Great little experiment bystander! I used earphones to listen to your recording. I feel like that is what it must be like for the BSA, sitting inside the powerbase with a motor on either side. It's a wonderful magnetic stethoscope you've built there.

JD

[ElectraGlide]

I always thought the best thing about the Segway was it's quiet ride!
Some people have way too much free time on their hands ; )

Steve

[terryp]

Hey - if Doug says it's cool, it's cool :)

Segway - What's holding you up?

[GyroGlider]

Cool stuff,
where can I get the inductive coil pickups ?

I am thinking about programming a microcontroller that counts the pulses of the motors and outputs a pre-recorded sound-loop based on the speed of the motor(s).

Anyone seen or remembers the movie "the wraith"( from the 80´s ) with Charlie Sheen.
A SEGWAY that sounds like the mysterious "Turbo Interceptor" !!!
Or how about a the sound of a "T-Fighter" from StarWars.
Would´nt that be cool :D

[bystander]

Speaking of headphones, that's the first way I tried it out. Adding the speakers was the next step, in order to demonstrate the effect for others. I'm thinking about putting the on/off switch on the handlebar for use as a "bell" (a.k.a. "pedestrian alert").

I've only had a little use in public with the speakers so far, but in some ways it's a little more civil. It's difficult to take someone by surprise when they can hear you 15 yards away. In many cases, it is better not to accidentally "sneak up" on pedestrians.

Since the (un-augmented) HT quiets down even more when moving slowly, some folks are quite surprised to see the HT, no matter how slowly I pass them. We all know the HT is not completely silent, but it can seem nearly so when there is ordinary traffic noise present in the background.

It's a similar situation as when you're riding your bike, and the chain squeaks a little. It's a small thing, but others on the road and near the road (on the sidewalk) are given a "heads up" slightly ahead of time. I have found after I lube the chain on the bicycle (making it quieter), I need to be more careful in some situations, because there is less advance warning to others.

When gliding late at night, of course I turn the speakers off when passing residential areas, something you can't do with a gas powered scooter.

---

I can't say I'm not guilty of too much free time on my hands, but...

There are a few hobby type applications that can follow along this avenue of research.

1. An ordinary bike speedometer can take a couple of seconds to register changes in speed. A HT can change speeds in a fraction of a second, so it might be nice to have a more responsive speedometer.

The zero-crossings of the pulses can be used to make an accurate odometer/speedometer. It's fundamentally more accurate than an ordinary add-on bike odometer, because you count 48 pulses per wheel revolution, rather than just one. (Think of measuring distance in steps of 1.25 inches instead of steps of 59.7 inches.)

If even shorter distances / time intervals need to be measured, multiple sensors can be deployed in an array.

It's a little bit of overkill though, due to inaccuracies such as exact tire inflation, microturning by shifting your weight sideways, or occasional slight losses of traction (slipping).

2. The pulses from the wheels can be combined electronically to make an electronic "South Pointing Chariot". Just maintain a counter such that it's value controls a heading indicator. The counter would wrap around at a value of 96 or so. Have the pulses from one wheel count up and the other wheel count down. As you turn the HT around, the heading will change relative to the HT's chassis, but the indicator will remain pointing in the direction it started out in.

Some interesting history about the mechanical version of this can be found on a google search (http://www.google.com/search?biw=818&hl=en&q=south+pointing+chariot).

3. The quadradure of the signal on each motor can be sensed to make a quite accurate "dead reckoning" estimation of each wheel's forward and backwards travel. This might be used for part of a do-it-yourself "E stand". (The other part would be a mechanized weight shifter or BSA shifter).

4. Haven't got to the guitar pedal effects box yet, that may sound even better, or maybe not. If someone had a pair of spare pickups from a bass guitar and mounted them under the motors, it might give a richer sound.

5. This might be an "attention getting" device for a parade, rental operation, dealership, or advertising project. You wouldn't want it too loud to be an annoyance though. Maybe you could leave the noisebox powered on for most of the time, then turn it off for short periods to demonstrate "stealth mode".<grin>

6. I found the amplified speakers I modified are available for even lower cost ($8, plus tax, S&H) online at outpost dot com (Item # 3661595), so there's no excuse that it has to be expensive.

[yosgof]

Bystander,

Cool stuff especially with the additional ideas.

Zero crossing though???? I Wonder how many people got that. Also the thing with the quadrature may be a bit puzzling.

My suggestion is also add a heart beat monitor (wire yourself in the loop) and combine is with the pickups from the HT.

Image the effect at 12Mph.

- Yossi
http://gallery.photo.net/photo/3365119-lg.jpg

[bystander]

quote:Originally posted by yosgof

Bystander,

Cool stuff especially with the additional ideas.Thanks for the feedback.quote:Zero crossing though???? I Wonder how many people got that. Also the thing with the quadrature may be a bit puzzling.No worries. If people are that curious, they'll look it up on Google or ask for more details. If their eyes glaze over, they won't.quote:My suggestion is also add a heart beat monitor (wire yourself in the loop) and combine is with the pickups from the HT.

Image the effect at 12Mph.Sort of a bio-feedback karaoke (http://www.answers.com/topic/karaoke) machine? Then all the pretty girls will wonder why my HT is making that "wolf whistle" sound...

[bystander]

quote:Originally posted by GyroGlider

Cool stuff,
where can I get the inductive coil pickups ?
You can make them. I wrapped about 5 feet of magnet wire around a piece of scotch tape (wrapped sticky side out around a 3/16 inch rod). It was probably around 80 to 100 turns. Then I put another piece of tape around the outside to hold the coil, then slid the tape/wire off the rod and onto a short steel machine screw. The pair of coils must of cost all of 39 cents. Finished coil is approx. 1/2 inch long and 5/16 inch diameter. The magnetic field from the HT motors is so strong, the coil's parameters are not critical.

Magnet wire is a fine pitched (24-32 gauge) copper wire with an enamel coating. If you have trouble finding it at the store, take apart a small broken transformer or small broken DC motor and unwind the coil. Speakers have magnet wire coils too, but the wire is so fine, it may be hard to handle. However, with a speaker, if you can get the coil out intact, it is already wound in a coil form! All you have to worry about is getting the ends attached to the rest of the circuit.

If you have a spare guitar pickup, that could work too, but I don't have one handy and don't know if it works for sure. I think a guitar pickup has a coil for each string, so you wouldn't need the whole thing, just part of it. Maybe if you used the whole set of coils in the pickup, a more complex sound could be heard.

If you want just the fundamental frequency from the motor, mount the coils closer to the center of the platform, (but not in the exact center, there aren't any signals there). The places I indicated on the picture have signals with more "ringing" on them. About two inches inboard from the spots indicated still have a strong magnetic signal without too many harmonics.

[yosgof]

For the lazier readers here’s one for 5 bucks. http://www.lessemf.com/kits.html

The whole shebang for 17.


- Yossi
http://gallery.photo.net/photo/3365119-lg.jpg

[bystander]

quote:Originally posted by yosgof

For the lazier readers here’s one for 5 bucks. http://www.lessemf.com/kits.html

The whole shebang for 17.


- Yossi
http://gallery.photo.net/photo/3365119-lg.jpg


Good find.

I had forgotten about those. I was looking for those before I started the project and found that Radio Shack no longer carried them. The next nearest place, across town in Van Nuys (http://www.allelectronics.com), was out of stock until just recently (http://www.allelectronics.com/cgi-bin/category.cgi?category=search&item=TPX-1&type=store), so I ended up improvising with the magnet wire.

Don't forget about the stereo pre-amp. I used a pair of LM368 ICs and six 10 uf tantalum capacitors. I had these in my junk parts bin, but these parts would retail for $2 to $4 total (new) depending where you purchased them.

If these were mass-produced offshore, the manufacturing cost ought to be less than $5, so you would think it could retail for $15 to $20.

Just a guess though, there's transportation, warehousing, licensing, distribution, return items, taxes, import fees, advertising, etc.

---

The Radio Shack audio amp pictured under the magnetic pickup (at the EMF Safety Superstore) will amplify the signal from the coil, but it may not be loud enough to hear in traffic. Ought to be OK for headphones though. If I recall correctly, that RS amplifier has one LM386 as it's amplifier IC.

This would be a good way to check out the sounds with off-the shelf equipment in a fairly inexpensive manner.

[yosgof]

Bystander, now add this baby (converted to DC) http://www.hobbytron.com/vmk110.html

- Yossi
http://gallery.photo.net/photo/3365119-lg.jpg

[JD]

Bystander,

It would be fun to hear how it would sound if you recorded the signals directly from the pickup coils, thus eliminating the gear and other ambient noises.

JD

[xsegwayer]

Hello all,
Long time time lurker....first post. I think that if you eliminate the gearbox freqs you won't find the sound to be as pleasant. The overriding substance that I hear is the gearboxes running through their sweep. I believe the gear meshes were designed to always be ~two octaves apart. Their "chordal" design is what is sounding so cool!!!

[bystander]

Heh,

Engadget posted these back on June 28th, I just came across them now. (I was vacationing last week.)

For a car: Vroom Box (http://www.vroombox.com/) (not for sale yet)

For a bicycle: TurboSpoke (http://www.turbospoke.com/products.asp) (seems to have started distribution at the end of June 2005)

Audio samples can be found on the pages of the above links.