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Considering a DIY segway

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Nickosha

New Member
Hello, I am building a segway with my class and I was wondering if anyone has some advice or if anyone could help us with some of the questions we have.

1. How strong of motors do you think would be necessary? Atleast how much torque do you think we need?

2. About the motor drives, are there any relatively inexpensive commercial products we could use or is it difficult to build our own. I understand that an h-bridge isn't a very complicated design, but are there important features we'd miss out on by going that route?

3. From our initial research, it looks like you need to use a 2-axis gyroscope and an accelerometer for control. We are not sure what to look for in the specs though. Are there any someone could recommend?

Thanks for any help. We're really excited about this project. :D

edit: sorry, I think this is the wrong section for this. Could a mod move it over?
 
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Mr RB

Well-Known Member
Elektor magazine just did one, a major project in the magazine and they sell a kit too. Just be aware it won't come cheap, you need 2 high power gearmotors, good chassis wheels etc, good high current hbridge motor drivers, complex sensors and some clever programming.

Once you start talking "where do I get inexpensive X" then you might be better off with a another project like a DC gearmotor cart that only needs 1 gearmotor, 1 hbridge and the easiest of programming. And will be just as much fun to ride if you make it fast! ;)
 

DirtyLude

Well-Known Member
Ya, that DIY one in the article still came out to somewhere around the $2k mark. Yikes.
 

Nickosha

New Member
Sorry for not responding until now. Thank you shortbus and Mr RB for the references.

For the cost, I'm sure it will cost quite a bit, but some high school students with a few RIT students made one for under $1,000 for all the materials. It was much less because they already had some materials. We're kind of in the same boat as them. We have some motors that may work, a cpu, and materials for the frame. Basically we need the gyroscopes, batteries, gearbox, and the motor drives/speed controllers.

For the gyroscopes, I guess the question is if a simple hobby gyroscope like Pololu - LPR510AL Dual-Axis (Pitch and Roll or XY) Gyro with ±100°/s and ±400°/s Ranges would work well enough or if we need to use a more expensive type. We might need to just find out.

For the motor speed controller, we're just not really sure. We're not expecting to be going 15 mph or anything. I'm wondering if maybe something that can supply 20A or 25A continuous would be fine, since we'll be driving exclusively on flat ground.
 

etechdude

New Member
Hmmm... I'm also considering a DIY segway as an off-season project for my robotics team. We'll be paying for this ourselves (can't fundraise), so budget is a major concern. I'm still investigating/calculating, but here's my high-level analysis...

I'm thinking of using 2 CIM motors ($28 ea) and 2 AM Toughbox gearboxes ($88 ea), because they're relatively low cost, and the Toughboxes have the ability to add a second CIM motor if we decide we want more torque/speed later. Also, these were competition parts for last year's FIRST FRC competition, so I'm pretty sure I can find some used units for cheap. As an alternative, I think CIM motors with belts/pullies may be workable as a lower-cost alternative to gearboxes, plus it would be easy to add extra motors there too, if needed later.

Other major expenses will be the batteries (will most prob have to buy whatever's available) and wheels (hoping to find something useable at Harbor Freight). Metal/materials for the frameworks should be available as scrap from various places, including some I have already. Electronics/control system is the easy part for me, as I've got lots of that already, though I'm considering changing to something with an easier programming interface for the students, such as perhaps a basic-stamp or Propeller.

I've seen others do this for under $1000, but I'm hoping to come in around $600-$700. No commitments on that yet though.

Cheers,
-Neil
 

Nickosha

New Member
After some research, I think that we will use the adxrs614 single axis gyroscope and adxl203 dual axis accelerometer for control. They have both been used successfully in other DIY segway projects, so I'm pretty sure they will be fine.

I've also found two different examples of DIY segway projects using the $125 Sabertooth 2x25, so I'm happy to find out that we could cut so much off of our estimated cost. I'm not sure I'd expect it to be suitable for slopes, but it looks like it is more than fine for flat ground.

On the motors, we already have a few pairs so I'm pretty sure we're all set there. One of them already has the gears set up to what we may need, but we'll have to do some testing on that.

The batteries are probably going to need to be purchased. There are SLA batteries that are cheap and hold a large charge, but they are heavy. Alternatively we can run several Lithium batteries in series and parallel. They are lighter, but also much more expensive and relatively complicated to set up. We haven't made any decision on this.

The wheels we're still thinking about. It mostly depends on how much room we need under the base.

Anyways we're working on it, but it will have to wait because we're on holiday break as of two days ago, so Merry Christmas!
 
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