Has anyone built a segway?
 

Has anyone built a segway? I remember dean saying that it was possible to build a segway using the parts in the kit, but I havent seen anyone take on that task yet...

I want to try and make something of the sort, possibly with one wheel and no handlebars... ;)

tenkai

A unicycle Segway? Sounds lovely.

I haven't made one... but we're gonna I think. With the gyro and all... same principle I guess. Just for fun. Or maybe we're not going to. It's possible though. You should do it.

I remember a team at the nationals who had a 4 wheel 'Segway' that was very crude but worked! Then again, there wasn't any challenge to making something that'd run on 4 wheels. Nonetheless, it'd be fun to play around with.

About a uni-Segway...
Say you made one with one ball instead of a wheel and you stood on a platform on top of the ball. The board would fit over the top half/third of the ball and have motorized wheels between the platform and the ball (somewhat like those old-fashioned mice with balls, except the uni-Segway would motorizzed the wheels inside it) Whichever way the rider leaned, the platform would roll the ball to be under their center of gravity just like a segway does, except this would go in every direction. It would not need a steering handle, but it would move without turning the rider unless you programmed it to rotate as it rolled to make the platform face the direction that the ball was rolling. This would then require the user to get onto the uni-Segway from one direction every time and would also make strafing impossible unless you turned you body a different direction from your legs (which isn"t very hard if you ask a marching band nerd.) I would rather just have to turn to uni-Segway through inertia and friction (like how you turn a rolley chair without touching anything) and then be able to slide right and left without facing that direction (can't you picture the military fighting with these and strafing back and forth on little balls?) It would be really cool to see someone do this, so if you want any help designing it, contact me at pauluffel@hotmail.com.

My old team, 122 The NASA Knights, is currently building one. Can't really tell ya how far along on it they are, though I'm almost positive that they have the base complete and motors/wheels mounted. Sooner or later one of them should see this post and will be able to tell ya all about it.

~Tom Fairchild~

Sooner it seems :)

Actually, we have a working segway, minus the auto-balance code. If you lean forward to balance the segway, then you can move forward. It is very slow right now, and I doubt it will ever be close to the real thing, but we have plans to use it to tow our cart ... and I think that'd be a sight to see.

Anyway, maybe another team member can post pictures or something.

Stephen

My idea for the uni-wheel segway wasnt using a ball (but that is quite an intreging idea) It was to just make it with one wheel, and have it require balance on the user's part for the side to side motion. If anyone has used a Voodoo Balance Board, you will kinda know what im talking about, but the rocking thing wouldnt be there.The way you would turn would be to go forward or backwards and lean to the right or left. Just you wait! you may see me at the NYC regionals zipping around, or racing Dean!

tenkai

Ya... I love it. 'Minus the Auto-Balance code' :)

I hope you arn't using a standard robot computer. I think that it would be impossible in PBASIC. A lot easier in C. (Well... still hard as heck, but still easier that PB.)

I'm trying to think. How would the program decide if the user is leaning forward, and thus wants to go forward, or if the unit is 'falling' forward and the user wants to stay still. I remember seeing Dean at the 2002 kick off standing on a ramp. The segway would go up...&...down...up...&...down. Pretty funny. I think that they improved the code, because as i remember, when i saw if again on a ramp, it didn't move at all.

They have improved the code. I was able to ride a segway only a couple months after they came out. Then I rode one this summer. When I rode it the first time it would kinda shake if you wanted to stay still. Then this summer when I rode it it was smoooooth.

The model I rode was the I-Series

I have been working on my own sort of mini-segway. It won't actually carry anyone (except perhaps a small rodent) but it will still be very cool. Im using an OOPic as the controller and a model helicopter piezo gyro for balancing. Eventually it should be able to drive around autonomously. The project has been stalled recently for lack of machine tools to build the chassis, but it looks like I will be able to use our school's CNC Bridgeport very soon. If it is ready in time I will bring it to the Pacific Northwest Regional and (hopefully :-) nationals to show off.

There's no computer on it as of right now (it is really hard to stay on for any good amount of time). It can just move back and forth OR spin in a circle... We still haven't found a good 4-way switch or small joystick we can use. Any ideas?

It wouldnt have to decide if it was leaning forward or falling. The effect produced is the same in either case. If it is falling forward, then the Segway will move forward to compensate, and balance the machine. If the driver was leaning forward, then it would move forward to compensate as well, but the weight of the person would keep it leaning forward,and hence, keep it moving forward.

Oh, BTW. Go take two wheels and a platform and set them up like the Segway, see if you can stand on it. Check out this short vid of one of our mentors balancing on it.

Is he balancing or is the device balancing for him

He is balancing.

O well whats the point of that?

1) To show off our nice engineering (though it doesn't balance, it's still pretty cool)
2) You notice he goes back and forth. It is surprisingly hard to keep the thing balanced while going in one direction for any significant period of time.

Summation: Dean Kamen is a genius. You don't realize how brilliant the Segway is until you try to do it yourself without computer help.

O, I totaly agree. I dont expect a FIRST team to be able to develope a segway, it would be so increadably hard! I just got really really exited!

Although I have not personally tried to balance on that device without a computer, just from looking at the segway I am not particularly impressed. Considering the center of gravity is below the center of the wheels it will naturally balance even without motors. Granted it would be foolish engineering to do otherwise, since it would be more likly to tip over; but I'm still a little disappointed.

Did your mother drop you as a child (j/k). I am not sure what you are getting at, but when a rider is on the segway it will not balance on its own without the machine being active. I mean it IS possible for a rider to find his/her center of gravity and shift it as they moved, but that would take soooooo much skill.

It naturally balances while you are standing still. Once you get moving, it's a whole different ball game.

Not really, if you were to put the device on an incline and stand on it while it rolls down it would be no different than while it is moving from your point of view. From your perspective constant speed will be just like standing still. Therefor all the motors need to do it maintain constant speed when you are upright, and accelerate you in whichever direction you should lean. That both prevent the device from tipping over and allows you to control its motion.

Like I said, try it, then you come back and tell me that.

Segway CG back of envelope calculations
 

I'm afraid you're wrong in this case, Max.

The average (height-weight proportional, for those of you who read personal ads ;-) ) person has a center of gravity that is roughly around sternum level standing straight. If you don't believe me, take martial arts that require falling (Judo, Aikido) or watch a ballet dancer in action.

Now, the segway is about 80 lbs, and typical non-Ally McBeal person is at least 120 lbs. So, even if the Segway's own CG is below the pivot axis of the wheel - the combined CG of the rider *AND* machine cannot be. Unless the Segway is MUCH MUCH heavier than the rider, which is not the case.

Your mentor's humble 2 cents anyway ;-)

Ah, but what you failed to take into account is the instinct not to fall over. A person will instintivly keep their center of gravity over their feet, therefor, for all our purposes, putting it at their feet. If the feet are below the axis of the wheels, they will reenforce the low center of gravity of the segway (even tho with that hand rail the segways own CG is probably above the axis of the wheels).

Except we do that by taking a step if we feel off balance. Not possible when standing on a Segway style platform.

So you mean to say that if you stand on a 1 foot by 1 foot platform that is tilted under you you can't keep your balance? CG occupies a point rather than a space, so you can shift your weight from foot to foot or toe to heel. If a person were not able to maintain their center of gravity over their feet they would not be able to climb a hill on account of their body remaining perpendicular to the slope and eventually tipping over.

Actually, no, you can't. Like I said, try it.

If you take that platform and put 2 wheels on it, I bet you'd have a very difficult time balancing on it.