Author Topic: Need Help finding corect motor  (Read 626 times)

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Offline RcstarttofinishTopic starter

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Need Help finding corect motor
« on: July 30, 2012, 03:38:28 PM »
I need help finding a motor than could support 50+ lbs at 1 & 1/2 ft away. It needs to be 12 or 24 volts and relatively small. I am thinking about building an exoskeleton. Feel free to add sugestions or comments even if they do not help with this exact question. Thx!

Offline Soeren

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Re: Need Help finding corect motor
« Reply #1 on: July 30, 2012, 06:52:07 PM »
Hi,

I need help finding a motor than could support 50+ lbs at 1 & 1/2 ft away. It needs to be 12 or 24 volts and relatively small.

That's a solid 14400+ ozf-in (102+ Nm).
Whenever you use the term "relatively", you have to add something commonly known that you relate to. As is, we don't know if you mean smaller than a cordless drill motor (impossible), smaller than a Jaguar V12 motor (possible) or whatever.

I can assure you of one thing though... Since you need around 10 times the power of a windshield wiper motor, it sorta shoots your exo down, as you'd need huge batteries as well.
Huge batteries are heavy, so you'll need more power => even larger batteries (that are still heavier... etc.)

Perhaps rethink why you want all that torque and whether there's alternatives - balancing out moving objects may make it possible with much less power.


I am thinking about building an exoskeleton. Feel free to add sugestions or comments even if they do not help with this exact question. Thx!

Suggestions: Learn physics, learn math, learn electronics, build robots, have fun (which you do by the former 4 ;D) and finally, cut down on the SciFi movies ;)

Exos are nice and I do have plans for making one myself (possibly just for arms and hands), not to give me superhuman strength though, just to keep a moderate human strength, as rheumatoid arthritis is happily eating away on my physical possibilities year by year and in a decade or two, I'll probably really need it just to take a p*** - I'm just hoping (without great hope though) for technological quantum leaps that will make it possible before then - as of today, it's pure SciFi.

For something a little more real, you might wanna check out what a MIT team has been brewing on for years on end (and with funding that no private person can get near).
http://web.mit.edu/newsoffice/2007/exoskeleton-0919.html
A bit pretentious to call it an exoskeleton IMO - exo-legs would be a more appropriate term.

Quote from: the linked page
Our dream is that 20 years from now, people won't go to bike racks--they'll go to leg racks,

Where "20 years from now" and "leg" is the bits worth noting, when you wanna check the level of exos (and when a designer says 20 years, we all know it's a wild guess, as nobody really knows what happens in that span of time - it may just as well be 50 years - anybody seen the flying cars which, in the fifties, was predicted to be every mans vehicle in 2000?
(Predicted by people you'd normally view as smart).

The real key to making exos possible and viable is a super-giant leap in rechargeable battery technology, so let's all cheer for the chemists (not those operating from a shed in the Colombian jungle though).
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline RcstarttofinishTopic starter

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Re: Need Help finding corect motor
« Reply #2 on: July 30, 2012, 07:11:59 PM »
Funding is not an issue. I guess that instead of batteries it could be corded. So I am looking for a 120v (U.S.A Wall Socket) motor with at least 50+ lb ft of torque that is "relatively"  ;) small (The largest would be the size of your thigh).

Offline Soeren

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Re: Need Help finding corect motor
« Reply #3 on: July 30, 2012, 08:46:18 PM »
Hi,

Funding is not an issue.

Then just contact someone like Maxon, they can surely help you with size info etc.


So I am looking for a 120v (U.S.A Wall Socket) motor with at least 50+ lb ft of torque that is "relatively"  ;) small (The largest would be the size of your thigh).

A DC motor is much easier to control and you could use a switch mode converter to give you the DC from the mains.

But really... According to your other post (please don't double post), you haven't build robots before and an exo is a far cry from a beginners project - I'd suggest something like the $50 robot from this site as a first project and then a series of gradually more complicated projects, before taking on something that nobody has ever really succeeded in.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline RcstarttofinishTopic starter

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Re: Need Help finding corect motor
« Reply #4 on: July 30, 2012, 09:05:11 PM »
I am new to the forum not robotics  >:(  8)

Offline Soeren

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Re: Need Help finding corect motor
« Reply #5 on: July 30, 2012, 09:30:53 PM »
I am new to the forum not robotics  >:(  8)

Well, then I really don't understand your other post, but perhaps you're a really quick learner?

I am a newbie to robotics but i need a motor [...]
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline RcstarttofinishTopic starter

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Re: Need Help finding corect motor
« Reply #6 on: July 31, 2012, 08:28:06 AM »
Sorry I meant a newbie to the forum  ::)

Offline jkerns

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Re: Need Help finding corect motor
« Reply #7 on: August 01, 2012, 08:10:05 AM »
How are you connecting the motor?  Belts, gears, levers etc. will change the motor torque requirements (and speed).
I get paid to play with robots - can't beat that with a stick.

http://www.ltu.edu/engineering/mechanical/bachelor-science-robotics-engineering.asp

 


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