A servo system is a feedback control system used to accurately follow or reproduce a process. It is also called a follow-up system. In many cases, a servo system specifically refers to a feedback control system where the controlled variable (the system's output) is mechanical displacement, displacement velocity, or acceleration. Its function is to ensure that the output mechanical displacement (or rotation angle) accurately tracks the input displacement (or rotation angle). The structural composition of a servo system is not fundamentally different from other forms of feedback control systems.
1. What is a servo system?
A servo system, also known as a follow-up system, is a feedback control system used to accurately follow or reproduce a process. A servo system is an automatic control system that enables the output controlled variable, such as the position, orientation, and state of an object, to follow any changes in the input target (or given value). Its main task is to amplify, transform, and regulate power according to control commands, making the torque, speed, and position control of the drive device highly flexible and convenient. In many cases, a servo system specifically refers to a feedback control system where the controlled variable (the system's output) is mechanical displacement or displacement velocity and acceleration. Its function is to ensure that the output mechanical displacement (or rotation angle) accurately tracks the input displacement (or rotation angle). Its structural composition is not fundamentally different from other forms of feedback control systems. Servo systems were initially used in defense and military industries, such as artillery control, ship and aircraft autopilot, and missile launches. Later, they were gradually extended to many sectors of the national economy, such as automatic machine tools and wireless tracking control.
2. The role of a servo system
Servo systems are developing rapidly not only in theory but also in their application devices. Modular, digital, high-precision, and long-life devices are updated and replaced every 3-5 years. Traditional AC servo motors have soft characteristics and their output characteristics are not single-valued; stepper motors are generally open-loop controlled and cannot accurately position, and the motor itself has a speed resonant region; PWM speed control systems have poor position tracking performance; frequency conversion speed control is simple but sometimes lacks accuracy; DC motor servo systems are widely used in position servo systems due to their excellent performance, but they also have disadvantages, such as complex structure, prominent dead zone at ultra-low speeds, and noise and maintenance issues caused by commutation brushes. New permanent magnet AC servo motors are developing rapidly, especially after the development from square wave control to sine wave control, resulting in better system performance, a wide speed range, and superior low-speed performance.
3. Working principle of a servo system
The controlled objects of a servo drive system are the displacement and speed of the machine tool's coordinate axes, and the actuators are servo motors or stepper motors; the part that controls and amplifies the input command signals is called a servo amplifier (also known as a driver, servo unit, etc.), which is the core of the servo drive.
A servo system is essentially a follow-up system. The controlled variable is either displacement or its derivative with respect to time. To define a follow-up system, it's a system whose output reproduces the input signal as quickly and accurately as possible. Metrics for measuring this include overshoot and latency.
A servo system is an automatic control system that enables the output controlled variables, such as the position, orientation, and state of an object, to follow any changes in the input target (or given value). The main task of a servo system is to amplify, transform, and regulate power according to the requirements of control commands, making the torque, speed, and position control of the drive device highly flexible and convenient.
