small hub motors

Does anyone know where to buy a small hub motor and wheel? I am looking for something in the 8 to 14 inch range and maybe about 10 to 20 watts.
Google only seems to turn up bicycle hub motors that only go down to 250 watts 10 180 watts.
The robot is for a friend of mine who has MS. He has trouble moving simple stuff, like a cup of coffee, from one room to another.
thanks Bob Smith
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Bob:
You might try to find a motor and hub at:
<http://banebots.com/
If you do not like the motor selection, you might try:
<http://www.anaheimautomation.com/
I've never bought anything from them, but they seem to have a fairly broad selection of motors.
-Wayne
Bob Smith wrote:

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Wayne C. Gramlich wrote:

Thanks, Wayne. I'm looking specifically for "hub motor" not a motor and hub. Hub motors are pretty popular for bicycles and are reasonably prices but are too big for this project. Maybe there is just not enough of a market for what I'm hoping to find.
thanks Bob Smith
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Bob Smith wrote:

Sorry 'bout that. I never heard that distinction before. When I Googled "hub motor" I got a whole bunch of hits, so now I understand the difference.
-Wayne
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Bob Smith wrote:

The best I've found so far is at http://www.goldenmotor.com / Click on "Hub Motor". More power and weight than I'd like but the size and price are right. I wonder if I can modify these so the wheel is cantilevered and not on a fork.
Bob
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Bob Smith wrote:

Their wheel chairs did not use a fork. So I suspect that there is some way to do it. I'm not sure if it will work with specific one you are looking at tho'.
-Wayne
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A while back I was also looking for a low-wattage hub motor. I also came across goldenmotor.com who seemed to have the lowest wattage ones. But, their lowest wattage is still 75 watts. As for ones not needing a fork, the Model: HUB24S -- 8" Mono Shaft wheelchair motor is the lowest power one, but, it is 180 watts.
Why do you want a hub motor? For me, I thought it gave the easiest way to mount, and the best ground clearance for an outdoor application I had. But, in the end, there just weren't any low power ones that I could find. However, for your indoor application, other choices are available.
Joe Dunfee
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l o wrote:

Yeah, this was my pick as well. The problem is that two of these and a battery would be 25 or 30 pounds. I was hoping for something a little lighter.

My former boss has MS. He walks with case and even then has a very uneven gait. By "walks with a cane" I mean _everywhere_, including from room to room. The problem is that he would like to brew a cup of coffee in the kitchen and take it to his desk to drink. One good hand and one good leg and carrying a cane means he can not carry a cup of coffee (or much else) from place to place.
He is a pretty good guy with a good sense of humor, so when he asked if I could build a robot to help I immediately said yes. He and I are both hard-core Linux guys which is a big help. He can do the high level coding, leaving me to the mechanical stuff.
The idea is to have the robot respond to voice command and to go from station to station in his house. We will use his desktop computer for the CPU intensive stuff and use a Chumby for the on board computer. A Chumby is a well documented, low power Linux computer. We will use dead reckoning for navigation and will use bar codes printed on 8.5-by-11 sheets for landmarks. A web cam can scan the area for bar codes and, using triangulation, figure out fairly accurately where it is. The nice part of bar codes, web cams, and voice recognition is that almost everything we need is off-the-shelf Linux software.
Our plan is to build a prototype first and then discard it. I will use some motors from a kiddie car that I salvaged awhile ago. Wheels will be plywood with some 12 inch bicycle tires (but no inner tube for now). Ultrasonics for collision avoidance but I'd like to get to stereo vision at some point. Tail dragger to begin but I'd like to get a balancing robot at some point. We will have fairly big wheels so a balancing robot should be easy since we can keep most of the heavy items below the axle.
We'll use the Demand Peripherals BaseBoard4 for all the Linux to hardware interfaces so this should be almost trivial.
This is probably more detail than you wanted. I would appreciate any advice you can offer.
thanks Bob Smith
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Bob, why do you specifically want the motor to be a hub motor?
As for advice, i don't have any from real experience, but some thoughts did come to mind that may ring true to you. Keep in mind that my comments are more in the category of brainstorming.
Weight; I would think that the goal would be to make a robot that your friend can move around if necessary. Robots are known for getting stuck, loosing power, and just plain breaking down. A good robot won't do this a lot, but eventually it will.
Size; You friend needs to be able to get around the robot if it is stuck in the hallway. But, it also must be tall enough to be able to set a full cup of coffee on it, while he is standing. And of course, your friend isn't as agile as some, so these criteria are going to be more restrictive than it might if you were making it for yourself.
Perhaps if the wheels will just easily free-wheel if it is powered down. That way he can just push it out of the way if necessary. This might solve some of the weight/size issues.
There certainly are a bunch of criteria that all are in a fight against each other. It would be very wise to make an easy mock-up of possible dimensions, and weights.
As for a balancing, that tends to make me nervous. Your friend is going to have a harder time cleaning up after a mess than your would. Sure, we have all seen projects showing off a 2-wheeled robot balancing a tray with a beverage. But, you are not a research institute. I think you might be better off sticking with something very reliable.
A differential drive with a round base, and the wheels centered , and then a 3-rd caster, has its advantages with turning around in tight spaces. But I would also wonder about stability. If the house does not have carpet where the robot will go, then you are probably OK.. But, if not, then that 3rd wheel caster tends to cause the top of a server- bot to move a lot during transitions. Perhaps the robot should just be made smart enough to know that it must go extremely slow when transitioning to a carpet. Many round differential steering robots tend to tip back and forth , especially when they are made taller than the base diameter. I suspect it is best to minimize this. I wonder if it is better to not be a symmetrical round robot, but rather have the drive wheels more forward, so that you have a more stable base. The task of turning around gets more complex to program, but people do it for some robots.
Here is a link to one "Butler Bot", but I really suspect that it is only practical without carpets. It is based on a IRobot Create. Note that you can hack most Roombas, since they have serial connectors. But, the all suffer from issues going over carpet. http://blog.makezine.com/archive/2010/06/belvedere_the_butlerbot.html
This Toshiba prototype looks wonderful, but note that they are NOT demonstrating with a cut of liquid! http://www.switched.com/2010/03/12/wheelie-butler-bot-serves-dinner-lacks-witty-banter /
This one is interesting, but certainly limited to cans of beverages. http://www.norrislabs.com /
I imagine one good form to consider is that of a serving cart. I came across some round ones in a quick internet search; http://www.accent-furniture-direct.com/Alfresco-Home-21-0850-AFH1234.html http://www.accent-furniture-direct.com/Emu-ER6407-82-41-QS-EMU1172.html
Hope I gave you some ideas and stuff to consider.
Joe Dunfee
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Joe Dunfee wrote:

No really good reason. The prototype will use motors taken from a kiddie electric car. These motors have a ring gear around an axle that passes through the motor. I need to find a wheel and hub that will fit. This is kind of a pain. Bicycle wheels are made for a fork mount and I'd like a cantilevered wheel. A hub motor would make this a lot easier, especially one made to be mounted on just one side.

Frederic does not have much upper body strength so a stuck robot is a real problem, especially if it is also a heavy robot. The kiddie car motors have a very long gear train and will be difficult to move. For the finished robot I was thinking of hub motors (which are easier to move) and, don't laugh, a socket for a broom handle. The idea is that attaching a broom handle gives him some leverage to turn or pull the robot. The wheels are about 12 inches in diameter to get over a floor/carpet transition.

Right! You know those 5 gallon buckets? The prototype has the motors, batteries, electronics, and batteries in the bottom of two of those. The top bucket is removable. He can put stuff on the top lid, in the top bucket, and/or remove the top bucket.

Yep, 12 inch wheels and small hub motors would work

There are a lot of unanswered questions. Will a two-wheel, tail dragger work? Is voice control (which Frederic got working last night) really be the right way to control it? Will big bar codes and web cams be enough for localization? Will the ride be smooth and fast enough to be useful?

Agreed. Two wheels does solve the problem of getting pneumatic tires on all wheels. Also, if he really hopes to carry an open cup of coffee then the top platform will have to be balanced or gimbaled anyway. If the weight is below the axle it will tend to be self balancing. But agreed, this is not a priority.

Yes, it does need to go from floor to carpet. We can put in a ramp if required but I was going to use ultrasonics on the prototype to detect bumps. I would like to play with stereoscope vision as a way to detect open paths, bumps and for obstacle avoidance. All of this is still an open problem.
> Many round differential steering robots

The 5-gal detergent buckets for the prototype are not really round but are kind of rectangular. (I'll post a photo when the prototype is done.) Big drive wheels near the front and a caster on the back. As you suggest, stability may be a problem.

http://www.switched.com/2010/03/12/wheelie-butler-bot-serves-dinner-lacks-witty-banter /
Yep, you have the right idea for what we're trying to do. The Toshiba one seems closest.

You did, thanks!
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says...

Don't make him hobble around the house to get a broom. Make the socket fit the cane that he already has in his hand...
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In article <67317809-1fb7-4734-94c0-9608d8b97922

How about a short/wide robot with a low center of gravity during travel that can then lift a tray to service height? Think of something like a jumbo roomba with a scissor lift. In the kitchen a voice command will have it extend a tray up to perhaps 4 feet for the coffee mug. (Extra points if the tray has a "cup holder" like in a car.) The 'bot then lowers the tray for transport, drives to the desk, then on command raises the tray/coffee.
A tall 'bot would shake coffee out of the mug moving over carpet and abruptly starting/stopping. This bot would lower the tray/coffee closer to a center of gravity. Plus the lift height could be commanded for a person standing (lift to counter-top height) or sitting in a chair (perhaps to TV-tray height) for convenience.
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Uniden wrote:

This is a good idea but I don't know how to build something like this. Or where to buy it.
On a separate note, the idea of using the cane instead of a broom handle is also really good. I'll see if I do this.
thanks Bob
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McMaster.com has this;
Item #2846T11 Compact Electric Lift Table 500# Capacity, Adjusts 5" to 30" at 1 7/8" per second. 25" X 12" Table Size , $2,826.36
I imagine too expensive. Your experiments on the prototype will show if it is necessary. Human serving cars are 3" high, but I am sure people go very slow if they are going over bumps. Perhaps there can be a compromise in the height. Maybe if the height were 25", it would still be acceptable height to put stuff on while standing, and stable enough to do transition to carpet.
[note that I also started a new thread "Server Robot" since we have strayed away from just the wheels so please direct future replies to that thread]
Joe Dunfee
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