Mechanics of a Servo Control System

A servomotor is an essential component of a servo control system or servomechanism. It is usually paired with an encoding device to accurately provide the speed or position feedback detail. However, not all servomechanisms require a servomotor. A domestic furnace is a good example of a servo control device that does not use a servomotor. The thermostat in a domestic furnace acts as a servomechanism in the sense that it depends on feedback and error-control; however, no motor is directly controlled by it for performing this task.  

Classification of Servos

Servo amplifiers can be further classified based on the type of their performances and their feedback control:

·         Type 0- This type of servos typically generate a constant output value when the error signal remains constant under steady state

·         Type 1- These produce a constant output value when the error signal is null under steady state conditions. However, a constant change of reference would imply a constant error in reference tracking

·         Type 2 – These are capable of providing a steady output value with a null error signal under a steady state. Here a constant change in the reference provides zero error in reference tracking but a steady rate of acceleration of the reference would mean there is a constant error in reference tracking

Here, the bandwidth of the servo control systems, indicate their ability to respond to the rapidly changing input commands.