Difference between DC and Servo Motors | Servo motor in delhi

Need a motor for your project, but not sure which type to get? Hopefully this rundown on the difference between DC and Servo Motors will help you decide! Servo motor in delhi

DC Motors: DC (Direct Current) Motors are the two wire (power & ground), continuous rotation motors. When you supply the power, a DC motor will start spinning until that power is removed. Most DC motors run at a high RPM (revolutions per minute), examples being the computer cooling fans, or radio controlled car wheels!

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 Motors: 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 the three wires (power, ground & control). The power to servo motors is constantly applied, with the servo control circuit regulating the draw to drive the motor. Servo motors are designed for more specific tasks where the position needs to be defined accurately such as controlling the rudder on a boat or moving a robotic arm or robot leg within a certain range.

These motors do not rotate freely like a standard DC motor. Instead the angle of rotation is limited to 180 Degrees (or so) back and forth. They receive a control signal that represents an output position and applies power to the DC motor until the shaft turns to the correct position, determined by the position sensor.

PWM is used for the control signal of the servo motors. However, unlike DC motors it is the duration of the positive pulse that determines the position, rather than speed, of the servo shaft. A neutral pulse value dependant on servo (usually around 1.5ms) keeps the servo shaft in the center position. Increasing that pulse value will make servo turn clockwise, and a shorter pulse will turn the shaft anticlockwise. The servo control pulse is usually repeated after every 20 milliseconds, essentially telling the servo where to go, even if that means remaining in the same position.

When a servo is commanded to move, it will move to the position and hold that position, even if the external force pushes against it. The servo will resist from moving out of that position, with the maximum amount of the resistive force the servo can exert being the torque rating of that servo.

DC Motors:

Fast, continuous rotation motors – Used for anything that needs to spin at a high RPM e.g. car wheels, fans etc.

Servo Motors:

They are fast, high torque, accurate rotation within a limited angle – Generally a high performance alternative to stepper motors, but more complicated setup with PWM tuning. Suited for the robotic arms/legs or rudder control etc.