Automatic control refers to the use of a control device or controller to make a machine, device, or production process operate automatically based on a predetermined rule. This involves adjusting the parameters, such as the amount being controlled, of the controlled object so that it operates in the desired state.
Automatic control theory is the technical science that studies the general principles of automatic control. In its early stages, it was based on feedback theory and was primarily used for industrial control. During World War II, the development of automatic control theory was advanced and improved as it was applied to the design and manufacture of military equipment, such as aircraft and marine autopilots, artillery positioning systems, and radar tracking systems.
After the war, a comprehensive system of classical control theory based on transfer functions was established. This system mainly studied the analysis and design of linear constant systems with single input and single output.
In the early 1960s, with the advent of modern applied mathematics and the use of electronic computers, automatic control theory entered a new stage of development known as modern control theory. This stage focused on the optimal control of multi-variable systems with high performance and precision. The main method used was the state space method.
Today, automatic control theory continues to evolve, with the theory of intelligent control, based on cybernetics, information theory, and bionics, becoming increasingly prominent.
Automatic Control System
To perform complex control tasks, the controlled object and control device are connected to form an integrated system known as an automatic control system. In this system, the output of the controlled object, or the controlled quantity, is a physical value that requires precise control. This could be a constant value, such as temperature, pressure, or flight path.
The control device is the complete mechanism that controls the controlled object. It can use different principles and methods to control the object, but the most fundamental one is the feedback control system based on the feedback control principle.
Feedback control system
In a feedback control system, the control device adjusts the controlled object based on feedback information obtained from the controlled amount. This information is used to continuously correct any deviation between the controlled amount and the desired control amount, enabling the control of the controlled amount. This is the principle of feedback control.