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What kind of motor do you think i need?

by ABHIdAVIATOR
Tags: kind, motor
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ABHIdAVIATOR
#1
Jan23-09, 04:38 AM
P: 22
hi,
I'm doing an experiment, in realisation of which i need to move a steel plate up and down. Please consider the following constraints faced by me:

-The plate would rise to 12mm at most.

-The speed should be such that it rises 12mm in around half a second.

-I want to be able to stop the plate anywhere between 0-12mm.

-Variation of the speed may also be needed.

-The plate will be exposed to high pressurefield above, so will tend to come down.

-I have only 75mm(L)*175mm(W)*25mm(H) space to accommodate the lifting mechanism.

-I can also mount the motor outside the above mentioned cavity, but the motor diameter less than 30mm is preferred.

After considering all the above mentioned constraints, i've thought of getting a miniature rack and pinion system manufactured. But the driving motor is still not finalized and i'm facing a problem in it. Initially i thought of using a geared dc motor but then i won't be able to stop it at the precise positions (4mm say). Servos can definitely be used but the speed control is a problem.
Stepper motor seems a good choice but i haven't got much experience working with them.

So, please help me choose a good motor or a new mechanism.

Thank you in anticipation.

Abhishek.
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ank_gl
#2
Jan23-09, 10:28 AM
P: 735
how about using a threaded shaft DC motor(make a small coupling) & a nut as the plate? It sure would give high reduction, space requirement is also isnt much, can be quick. though i dunno how well it would respond to speed requirement.
coreyh
#3
Jan23-09, 03:55 PM
P: 10
Hi Aviator,

Judging from your speed requirements, 12mm in 0.5sec, which translates into quite a steep acceleration profile, i suspect a power-screw setup will be too slow. I would recommend looking at a linear drive instead. It will be more expensive, but you can get really fast dynamic response as well as integrated position feedback. Check out these sites:

- http://www.faulhaber-group.com/servl...2/i428419.html
- http://www.copleycontrols.com/Motion...otors/sta.html

I used one of the ones from copley, STA1104 i think, for a project recently instead of building a crank/con.rod system hooked up to a motor. Keep in mind you need to buy the drive electronics as well. For their smallest servoTube i paid about 1000chf + 600chf for the control box. (1chf ~ 0.9USD) But compared to making anything custom this was a bargain. The drive comes with software and you can drive it from your PC or using an oscilloscope. You could also easily integrate it's control into a Labview application if it's part of a bigger experiment.

I would suggest to try and refine your speed, acceleration, load and space/mounting requirements and make a request to both of these companies. I do this all the time when i'm looking for a component, usually get tons of good responses!

Finally, you will need a linear coupling to connect the linear drive to your load. Ask in your request for a recommendation on this as well.

Hope this helps and good luck!

ABHIdAVIATOR
#4
Jan24-09, 02:55 AM
P: 22
What kind of motor do you think i need?

http://www.flickr.com/photos/3371122...65139/sizes/o/

this is a possible solution. I dont find a suitable motor.
i think steppers might work, but circuit is the problem. I dont have any exposure of microcontroller programming.

Well, thanks coreyh. Althought the solution you proposed is good, i'm not in a state to afford the same.


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