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Stepper Motor vs Servo Motor

Stepper Motor vs Servo Motor

Stepper Motor vs Servo Motor

(OP)
Hi all,

What's the main differences between stepper and servo motors and what applications might they be used?

God bless,

Phil.

RE: Stepper Motor vs Servo Motor

Stepper motors tend to be used without feedback i.e., send the motor 100 steps and assume it moves that 100 steps worth.  Servos use feedback.  Send them a command and look at the feedback and make corrections.  Both are used in machine tool applications as sell as other systems that need to move objects.

RE: Stepper Motor vs Servo Motor

Mechanically, the biggest difference is that a stepper is designed on purpose to cog, while an ideal servo has no cogging whatsoever.

That's a consequence of the control approaches described above.  A closed-loop control system wants linear, or quasilinear behavior, which obviates a coggable motor.

A stepper motor uses the cogging as a means of provide repeatable responses to stepping commands and to stay in the commanded position.

TTFN

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RE: Stepper Motor vs Servo Motor

Many modern steppers use "micro-stepping" technologies which provide much more smoother motion than they used to.  If the stepper torque is geared through a ballscrew or whatever, you may never notice it.

Servos generally can provide higher speeds, torques, and accelerations than steppers.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com

RE: Stepper Motor vs Servo Motor

A few thousand bucks.  

My advice is to only use steppers for very low-torque, rotational applications, like rotating a small part or free machine member.  Yes, I know that they make big stepper brutes, but I have had lots of problems with such applications in my 22 years' experience.  Anything that requires torque or acceleration of even moderate loads usually will need a servo.  The cost savings of the stepper will not be worth the headaches you will have with it.

Don
Kansas City

RE: Stepper Motor vs Servo Motor

(OP)
what exactly do you mean by cogging? thanks for all you replies.  

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