Principles Behind Servo Motors

by Virginia Franco

Servo motors have been around for years. Because of their small size, they are widely used by hobbyists and collectors to operate remote-controlled or radio-controlled toy cars and robots and even airplanes. Servo motors can also be found in one form or another in industrial devices where robotics are necessary. Servo motors can be found across a number of industries, from pharmaceutics to food services. This article will provide some background about servo motors, including what they are, how they work and how they are used.

What is a Servo Motor?

A servo is a small device with circuitry built right in. It has a positionable shaft that can be arranged in a number of angled positions via a coded signal. The position of the shaft changes as it receives different signals. Despite their small size, servo motors are powerful but don't consume much energy.

How does a Servo Motor Work?

A servo motor operates on the principal of "proportional control." This means the motor will only run as hard as necessary to accomplish the task at hand. If the shaft needs to turn a great deal, the motor will run at full speed. If the movement is small, the motor will run more slowly. A control wire sends coded signals to the shaft using "pulse coded modulation." With pulse-coded modulation, the shaft knows to move to achieve a certain angle, based on the duration of the pulse sent via the control wire. A 1.5 millisecond pulse will make the motor turn to the 90-degree position. Shorter than 1.5 moves it to 0 degrees, and longer will turn it to 180 degrees.

Servo Motors for Toy Enthusiasts

Servo motors can be found in radio-controlled toy cars

Servos are used in radio-controlled airplanes to position the rudders, in radio-controlled cars to move the wheels and in other remote-controlled toys like puppets.

Servo Motors for Industrial Applications

In food services and pharmaceuticals, the tools are designed to be used in harsher environments, where the potential for corrosion is high due to being washed at high pressures and temperatures repeatedly to maintain strict hygiene standards.

Types of Servo Motors

There are two types of servo motors--AC and DC. AC servos can handle higher current surges and tend to be used in industrial machinery. DC servos are not designed for high current surges. Generally speaking, DC motors are less expensive than their AC counterparts.

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.

Photo Credits

  • photo_camera http://www.seattlerobotics.org/guide/images/servo1.jpg;http://img.alibaba.com/photo/204106230/R_C_Car_remote_control_toy_car_.jpg