Here is some information about what I am upto I am making a smart windmill system in which the windmilll is able to adjust itself according to the direction in which wind is blowing in order to make the traditional windmill system more efficient so i have created a wind direction detection mechanism now I want to turn the dome of my windmill according to this detected direction with the help of some motor mechanism so I need help in choosing motor as the motor which i would be using now must rotate the dome 360 degree freely according to the detected direction ..................
Servos are cheaper and easier to program. I'd reckon you go for a servo.
If the windmill is small enough that you can find a servo strong enough to hold it in position then the servo will certainly be easier to use. For a larger windmill you would probably want to use a geared DC motor but you would need to include some type of position feedback as well -- like a wheel encoder or magnetometer.
The problem with using any sort of motor is the risk that it uses more power than the turbine generates. That's why small wind turbines just use a wind vane to point into the wind.
A geared DC motor would probably be best, and probably one with a worm gear so that it will hold position without power. However the wind direction changes very frequently so the motor will almost be moving continuously.
Stepper motors are out of the question - they use far too much power.
...R