What is a servo system?

Servomechanism, also known as servo system, is a feedback control system used to accurately follow or reproduce a certain process.

The servo system is an automatic control system that enables the output controlled quantity of the object's position, orientation, state, etc. to follow the arbitrary change of the input target (or given value). Its main task is to amplify, transform and adjust the power according to the requirements of the control command, so that the torque, speed and position control of the drive device is very flexible and convenient.

In many cases, the servo system specifically refers to a feedback control system in which the controlled quantity (the output of the system) is mechanical displacement or displacement speed, acceleration, and its function is to make the output mechanical displacement (or rotation angle) accurately track the input displacement ( Or turning angle), its structure is not different in principle from other forms of feedback control systems. The servo system was initially used in the national defense industry, such as the control of artillery, the automatic driving of ships and aircraft, and the launch of missiles. Later, it was gradually extended to many sectors of the national economy, such as automatic machine tools, wireless tracking control, etc. 

The structure of the servo system

There are various structures and types of mechatronics servo control systems, but from the perspective of automatic control theory, servo control systems generally include five parts: controller, controlled object, execution link, detection link, and comparison link. The following figure shows the principle block diagram of the servo system.

1. Comparison link

The comparison link is the link that compares the input command signal with the feedback signal of the system to obtain the deviation signal between the output and the input, and is usually implemented by a special circuit or computer.

2. Controller

The controller is usually a computer or a PID control circuit, and its main task is to transform the deviation signal output by the comparison element to control the actuator to act as required.

3. Implementation link

The function of the execution link is to convert various forms of input energy into mechanical energy according to the requirements of the control signal to drive the controlled object to work. The executive components in the mechatronics system generally refer to various motors or hydraulic and pneumatic servo mechanisms.

4. The accused

5. Testing link

The detection link refers to a device that can measure the output and convert it into the dimension required by the comparison link, which generally includes a sensor and a conversion circuit.