What is a Servo Control System

A servo control system is one of the most important and widely used forms of control system. Any machine or piece of equipment that has rotating parts will contain one or more servo control systems. The job of the control system may include:

* Maintaining the speed of a motor within certain limits, even when the load on the output of the motor might vary. This is called regulation.
* Varying the speed of a motor and load according to an externally set programme of values. This is called set point (or reference) tracking.



Servo motors are brushed or brushless servo motors with feedback, typically encoder or resolver. They can be rotary or linear motors. They require a complex closed loop control algorithm (such as the classic PID method). Normally the control loop has to be tuned, and servo dither can be a problem.. Due to the added control and feedback, typically servo systems are more expensive than stepper systems.

Servo motors typically have a peak torque of 3-10x the continuous torque, their torque curve is much flatter than the stepper curve, and the maximum speeds are much higher. Peak torque is a great thing; often, a system just needs extra power for a short time to accelerate, overcome friction, or such.

Our daily lives depend upon servo controllers. Anywhere that there is an electric motor there will be a servo control system to control it. Servo control is very important. The economy of the world depends upon servo control (there are other things to be sure – but stay with me on the control theme). Manufacturing industry would cease without servo systems because factory production lines could not be controlled, transportation would halt because electric traction units would fail, computers would cease because disk drives would not work properly and communications networks would fail because network servers use hard disk drives. Young people would become even more unbearable and they would complain more than they do now, because their music and games systems will not work without servo control.

Servo control systems are that important and it is vital to know about them. So pay attention and sit up straight – you are not on holiday and I am not writing this for the good of my health.