do i need a stepper motor or a dc motor?

[eng soso]

hello every one,
i am designing my undergraduation project, and i need to design an elevator , which one of these motors would be suite for the design?
(stepper motor or DC motor ) and if it is a stepper , is it accurate? or it needs a sensor to stop at spicific floor?
thanks,

 

[alexan_e]

A stepper motor has a specified angle step (for example 1.8 degree), if you use some kind of gear you can get much smaller steps but
for your application i think that you probably need a servo motor that gets a feedback from the sensors when to stop, it can be more precise than a stepper motor.
I think you would have to use sensors in any of the above to detect the correct level to stop, I'm not sure if you can avoid it by using a predefined amount of steps..

Alex

 

[MahmoudHassan]

without sensors:
both can do that ..... suggest you have building for which you design your project the distance between two floors say 3 meters
you can make experiments two know how many turns needed from your motor to move elevator from 1st floor to second and call it a "step"
then to move elevator from 1st floor to 5th floor you need five steps and so on
if you used stepper motor it will be more accurate than DC motor in design like that ...but take care
the motor performance and other mechanical parts must work perfect a designed but for long time working _say after a month_the system won't be perfect and so need to adjusted again and so this is why you must use sensors

if you want to use sensors it will be better and it is not needed to use stepper motor ...DC motor is ok ..i think.

 

[srhoar]

Lets assume the intent of the project is to learn about electro-mechanical systems.
You would normally use a DC motor (or AC) and gear it down. Use sensors to know its position. Then use some type of control system to make it work (uP,PLC,RELAY,Discrete, etc.)

To make the design simple, I (not being a mechanical engineer) would use the stepper motor. That way I could control its speed without having to use gears.

Everything else should be the same. Just trade off the gears (mechanical) for the stepper (electrical) for simplicity.

Hope this helps,

Red