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What exactly is a servo motor ?

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mImoto

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fanuc 6m servo setting

Hello,

I am a bit confused with the types of motor. I have seen the term "servo motor". Is it a DC motor? what is it exactly a servo motor?

Thanks in advanced and best regards,

mimoto
 

6m dcmotor

Hello mimoto
A servomotor is a motor specifically designed to be part of a servo system. No magic inside.
Some years (decades??) ago, the DC servomotor was the most common for moderate to high powers (there was a split winding AC servo with very limited power capabilities). The DC servo uses permanent magnets to linearize the transfer function (the iron in pole pieces of a separatelly excited DC motor is subject to demagnetization due to armature reaction)
wich is desirable for system stability.
Armature (rotor) moment of inertia is usually minimized to make the whole system more responsive.
Another point is the thermal design, a servo can sustain rated torque at zero speed (holding a hanging load for example).
The weak point of every DC motor is its brushes and collector.
The AC servomotor uses the permanent magnets in the rotor and the windings in the stator. But, to get a
rotating magnetic field you have to put position sensors in the armature to switch windings electronicaly (the same thing the collector in de DC motor does mechanically).

Hope this helps
 

Re: Servo motor question?

Maybe it is a stupid question but could you define what is a servo system?

Thanks again,

mimoto
 

Hello again, mImoto,
A servo system is a closed loop control system; that is, a system that uses some sort of sensor to correct the actions on a controlled variable in order to maintain it at a preset value. When you talk about a servo system, you usually are talking about a position control system. The most simple servo systems are implemented using a potentiometer as position sensor, that way you could process all the signals, SetPoint, ActualPosition, Error, and CommandOutput in analog form, using op amps for example.
Best regards.
 

Re: Servo motor question?

Servo motors allow the continuous variability of both the field and rotor winding currents. They cost more than ordinary motors.
 

Re: Servo motor question?

I guess if u want to know it's application, pressure sensitive lablers or encoders and resolvers is perfect example
 

Re: Servo motor question?

Hi take a look a motorpro they have a servo example as i recall

regards
 

Re: Servo motor question?

hello
I am need information for dc servo motor model (T-2000m & 6m with encoder) fanuc, as T(n.m) ,P(kw), V(v) , I(a)
 

Re: Servo motor question?

mImoto said:
Maybe it is a stupid question but could you define what is a servo system?

Thanks again,

mimoto

Hi mImoto,

Servo is original from latin language of slave which any device could follow
your order to do something you want to do is called a servo device.
Servo motor???
A motor that you can command it's postion,speed even torque could called a servo motor.
How to give your command to motor???Just give command to servor driver it will
translate your command into other form that motor could reconginze.

Good luck
 

Re: Servo motor question?

There is also an other type of motor that is stepper motor. They are somewhat equivalent to servo motors in functionality. Stepper motors do not rely on some feedback mechanism as it is in servo motors (potentiometer). Rather they rotate in small steps (fixed angular displacement per step). You can find more info through Google. :spoko:
 

Re: Servo motor question?

Servo system is a general term that represent such a system that has a feedback value which is used to correct the "Errors" in control function. In position control systems , all the time mechanical conditions varies , motor load and inertia changes ,even environment conditions like temperature is not stable and disturbs the control function. If you give a proper feeback to control function , you have a closed loop control and correct it when needed.

Servo motors can be AC , DC , permanent magnet and so on.
In my last project , I have used a BLDC (Brushless DC) motor as servo motor , and 3 hall effect sensors as feedback device. I design and collected a control system around PIC 18F452 and get perfect results under 120 USD.

Every servo system is not expensive ..
 

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