Which motor is beter stepper of dc motor

[mrel]

Hello
I would like to build security camera setup where by camera can pan and Tilt using either a stepper motor OR Dc to pulse width modulator motor device to control dc motor .
I am not sure if I need a dc to pulse width modulator motor device to use for a dc motor .
Thank for infor
mrel

 

[magnatro]

its better to use a stepper motor for better control with precise adjustments of the camera angles
but for a better result,
Use a servo motor..

 

[dknguyen]

A DC motor would give more accurate results and better performance BUT it also costs a lot more because you needa lot of parts to turn it into a servo motor:
-non-stepper DC motor
-a gearbox since DC motors turn too fast with too little torque for something like a camera pan-tilt (these in particular can get very expensive and hard to source)
-position sensors
-servo drive electronics (PWM being controlled by position sensors in a closed loop to maintain a fixed motor position. DC motors naturally spin contnuously so the electronics have to keep the motor halfway between forward and reverse to get them to hold a fixed position)

With the stepper it tends to be much cheaper but your results aren't as good. You tend not to need a gearbox since they spin slow with lots of torque. Also, because the design of stepper motors allow them to naturally hold a fixed position rather than spin continuously, they can be used in open loop control without position sensors. All you need is:
-stepper motor
-stepper motor drive electronics

The major catch of this is that since you are using the stepper motor in open loop control, the motor must have sufficient torque to reliably move to where it's told whenever commanded. You are essentially telling it to move by a certain amount and blindly assuming it always did so successfully. If it doesn't, the motor won't be where you think it is and you lose track of where the motor actually is. Also, no position sensors means the motor is not as accurate. Of course, you can always use position sensors (and compatible drive electronics) with stepper motors to get around both these drawbacks. But doing this negates one of the stepper motor's two advantages (no gearbox, and no position sensors).

If you don't know where to start, I'd say that DC servo motors are beyond your budget to buy everything premade or your ability to build them, and in many cases your ability to buy the parts to build them! THe exception is radio-controlled servo motors where everything is in a nice neat package already: motor, gearbox, sensors, and drive electronics. If your camera is small enough these are a good choice. I don't know how big your camera assembly is, but make sure to check them out first. A good place to start is www.servocity.com.

But for anything larger, steppers have the advantage of being MUCH more affordable as well as easy to implement. DC servo motors though, are the gold standard (in quality and price!)

 

[arunb]

stepper motor, probably with a micro-stepping drive would be better