what is the difference between simple dc motor and servo motor?

Question

Actually I am looking for conversion of high torque dc motor to digitally controlled servo motor using pot or encoder in simpliest way ..... i can use my PC for initial modelling.....

Answer 1

A DC motor uses a commutator built onto the shaft which will automatically change the polarity of the armature winding as the shaft rotates. This switching keep the magnetic fields between teh armature and stator is a state which keeps the armature rotating. With out commutation the motor shaft would rotate until the magnetic fields lined up N to S at which time the motor would stop turning.


In a SERVO motor a commutator is not used. Instead multiple sets of field windings are located about the Stator. A single pair of these field windings are energized at a time. The shaft rotates into alignment with the energized field and stops movment. To make a servo motor turn the fields are energized in turn (STEPS) to make a rotating field. The armature then follows this rotating field. In essence the "Commutation" or switching On/Off of the field coils is done electronically. This can be done with a driver circuit of a micro controller.

the advantage of a servo motor is precise rotational control which is based upon the number of steps/rev and any associated gearing. Very precise movments can be performs as attested to by there use in hard drives and automation.

DC motors provide torque. A high torque DC motor like a car starter is series wound. Other DC motors such as shunt wound are used in automation. THe advantage with the use of a DC motor is easy speed control by varying the voltage applied to the motor.

Rotational control of either may be done with some sort of feedbach mechanism such as a pot connected to teh shaft. The feedback is used as a signal to a motor controller which will stop the rotation of the shaft via control of the particular motor in use.

You may consider using the same motor you currently have and consider providing some means to control the motor controller which drives the motor. i.e 4-20 ma input to a motor controller which is designed to drive either a DC motor or Servo. You keep the existing motor and mechanical setup and change the existing manual motor controller to a type that will interface to your application.

Answer 2

A servo DC motor is used to control a load. It has the ability to move forward or reverse and hold a position. Servo are also equipt with an encoder for position sensing, they can be closed or open loop controlled. Think of a Servo like balancing a BAT on your palm. if the load moves you compensate, thats what a servo will do. DC motors generally run forward or reverse, servos can be geared down, but so can ac motors these motors are refered to as gearhead. There seems to be confusion between a stepper and a servo in some of the answers. In a stepper the poles of the motor pulse and the motor rotates one step, if no other pulses are give the motor holds its position like two magnets close to each other. A servo with spin (unless geared) The stepper holding power is what you feel when you turn a stepper motor it feels like rolling over little bumps. The more of these little bumps or windings you have around the motor the smaller the steps can be which can be related to accuray. It is easy to see how even a small load could mess with a stepper motor move weight forward and suddenly reversing it puts a strain on the hold power and the motor can skip steps. Servos actually get stronger when they are at 0 RPM they will draw a strong current just like start up. It is always a good idea to slow you servos down even quickly to avoid a sudden reverse it will help longevity of your cnc or robot etc. If you want to see how someone did a conversion of a dc motor go to http://www.truetex.com/servomod.htm
Good Luck!

Answer 3

Servo Vs Motor

Answer 4

A servo motor has a pot or encoder to monitor the shaft's rotational position. Often it is used to hold the shaft in place at a specific angle of rotation. The motor torque required depends on the load. Other uses are for precise location as in CNC machines where a feedback loop keeps track of how far the cutting head has traveled.

To convert a simple dc motor to a servo motor would require a means of attaching the pot or encoder to the shaft. Then reading the output and using the information to determine the shaft position and/or number of rotations.

Answer 5

DC motor :
-DC (Direct Current) Motors are two wire (power & ground), continuous rotation motors.
-The speed of DC motors is controlled using pulse width modulation (PWM), a technique of rapidly pulsing the power on and off. The percentage of time spent cycling the on/off ratio determines the speed of the motor, e.g. if the power is cycled at 50% (half on, half off), then the motor will spin at half the speed of 100% (fully on). Each pulse is so rapid that the motor appears to be continuously spinning with no stuttering.

Servo Motor :
-Servo motors are generally an assembly of four things: a DC motor, a gearing set, a control circuit and a position-sensor (usually a potentiometer).
-The position of servo motors can be controlled more precisely than those of standard DC motors, and they usually have three wires (power, ground &). Power to servo motors is constantly applied, with the servo control circuit regulating the draw to drive the motor.
-PWM is used for the control signal of servo motors. However, unlike DC motors it’s the duration of the positive pulse that determines the position, rather than speed, of the servo shaft.

https://www.electrikals.com

Answer 6

This Site Might Help You.

RE:
what is the difference between simple dc motor and servo motor?
Actually I am looking for conversion of high torque dc motor to digitally controlled servo motor using pot or encoder in simpliest way ..... i can use my PC for initial modelling.....

Answer 7

A servo motor is a motor that is massively geared down and fitted with a travel stop or a reversing switch.