Team 871 - Homebrew Segway

[sanddrag]

Originally posted by D.Fahringer
Thanks Sanddrag! That advice was right on the money!
The link works now!

Cool. Glad I could help.

For the speed, I'm sure we could push it past 12.5 mph with a couple chias under there. Manually, I don't know. I've never ridden a manual one.

[MrB]

everything regarding the craigwat is correct.

1) it does not turn, yet :-)

2) the rider still has to balance it manually, the code works, but the FP drivetrain is not strong enough to support a human riders applied weight.

3) a lower CF would help balancing, but while testing we needed ground clearance to allow for great changes in angle to test the gtro code. it increases with change in angle and we needed to test it as such..

4) WERNER, where is your "871 ALUMNI" TAG!!!!

(you spend years helping create a genius and then they pretend not to be associated with you :-)

[MrB]

hmmm, as for the 12.5 ft/second i'm doubtfut...

the segway is powered bt two 2kw specialty motors, i doubt we will ever come close to its output :-)

i'm more interested in skillful balancinf and asthetics.. we'll worry about speed in bersion 2.0 :-)

did i mention we are only at engineering prototype bersion 0.001 :-)

[D.Fahringer]

That is 12.5 mph... so all we have to do is 13-15 mph. Ahh the power of Chiaphuas! or the 1/2" drill with a custom transmission would have power enough to reach that speed but It would not leave any extra power for recovery of rider or terrain bobbles.

It would be a combined effort of the gyro control system and the riders effort similar to the Craigway prototype...if the rider doesn't allow the machine to get in a fight for balance it could be coaxed to get up to a higher speed.

The real Segway won't get up to it's speed potential if the rider doggedly leans forward trying to force it to go...

[GregTheGreat]

Originally posted by D.Fahringer
That is 12.5 mph... so all we have to do is 13-15 mph. Ahh the power of Chiaphuas! or the 1/2" drill with a custom transmission would have power enough to reach that speed but It would not leave any extra power for recovery of rider or terrain bobbles.

It would be a combined effort of the gyro control system and the riders effort similar to the Craigway prototype...if the rider doesn't allow the machine to get in a fight for balance it could be coaxed to get up to a higher speed.

The real Segway won't get up to it's speed potential if the rider doggedly leans forward trying to force it to go...

You might be able to pull of the 13-15 without the gyro balancing. The programming and motors can only compensate so fast. If you were to wish to make one that fast, I would recommend drill motors, but remember you would need casters in the front and back (that or an exceptional programmer). If you're programmer can make it operate at over 12.5 with the drills and be able to maintain balance, I will be hiring him to teach me his unbelievable skills. The drills are sloppy, and if you are attempting a speed such as that, use a Chiaphua, I think you might be able to use that with a high gear ratio (that and a very stable rider) and you might be able to pull it off. If you find a way, you can send me some video, and I will even host it for you. I don't think its possible, but if it is, I am sure you guys will figure out how. I wish you the best of luck on creating this unique project.

[sanddrag]

Originally posted by MrB
the segway is powered bt two 2kw specialty motors, i doubt we will ever come close to its output :-)

2kw for each motor? My electric scooter has one 450w motor and it goes 16 mph.

[Matt Krass]

Hey guys, can any of you electrical geniuses out there provide some info on Resistor-Capacitor circuits and how to use them with the edubot? I remember being told it could be done but not how. I want to use it to stabilize gyro output.

[Willum]

I worked out the physics behind the Craigway and essentially any gyro driven balancing scooter. I'll post it on the website asap. But it's 1am now, and i have a graduation rehearsal at 8am, and need to leave for prom at 2pm, so it may be a day or so before you guys see this stuff. It's neat and something to ponder.

I may have figured out how the Segway allows for 3 speed maximums, with three keys.

Will

[MrB]

go willium!!!

[Matt Krass]

Originally posted by MrB
go willium!!!

Heh, same here! I need all the info I can get!

<EDIT> Can you guys tell me the sensitivity of the gyro? I want to make sure it has enough clearance to react, like how far do I have to tilt it and how fast before its measurable? </EDIT>

[WernerNYK]

The gyro provided in the kit is _alright_. It provides pretty accurate readings at slow speeds of rotation. However, it can only sense so quickly... I dont know the numbers at all, but ie only 15 degrees of rotation/second, than it would max out and have to "reset" and that takes some time.

I would imagine for these self-balancing HTs that you all are trying to build the stock gyro will not present a large problem, but just FYI there are much better ones available from Digikey.

[Matt Krass]

Great, that helps a lot, I guess I better put a notice on there to nto snap it in any direction. Having the stabilization gyro pause to reset might result in a GW Bush! I still need to learn though, how far and fast does it have to turn before it will register? and what do you recommend for freedom of movement?

[D.Fahringer]

I was curious for some time about the exact cause of this drill motor slop in the transmission. I found it to be part of the variable load clutch mechanism and it can be taken out completely but you will have a little job on your hands. The slop results from the internal gear sleeve is prevented from rotating under load by balls that are spring loaded. These balls pass through the holes in the housing shown in the picture and the bumps on the back of the gear sleeve are so far apart that it will spin until the ball comes into contact. The fix? weld on more bumps! then it won't rotate at all. Minimal play.

The unit shown is a 2001 model but I suspect the same feature in the 2003.

The only problem then is the mounting of a long motor/transmission on the Segway gets in the way of where you would want to stand if you are going for the ultimate in low CG
of the machine.

[Adrian Wong]

Hello. Excuse me for intruding, but something has been bothering me since I started reading this thread.

Isn't the Segway and these other gyroscopically stabilized platforms an example of the common "inverted pendulum" control theory experiment?

If so, you wouldn't want to have a low center of gravity for the system. You would want the center of gravity to be higher (e.g. farther from the wheels).

Just a thought. Best of luck to everyone on these projects; they're very interesting to follow.

[D.Fahringer]

The lower the CG the easier it is to remain upright it seems to me. The fact that I can stand on the KnightKrawler without turning it on displays some inherent stability. The students and I have a little trick we do on it where we set the speed and a mild turn and then let go of the controls....(the "No Hander Meander").

Take a base where you stand above the axles of the wheels
and one where you stand below and try to balance....no contest!
If the wheels are free to turn the first one will get you in trouble right away!

I am keeping in mind that a yard stick is easier to balance on my hand than a 6 inch ruler and the yard stick's CG is further from my hand but I feel that is just a reaction time matter.

Anyone else have thoughts about this? It is interesting!