An industrial automation control system consists of a controller and a controlled object. However, to achieve complex control tasks, a typical automatic control system usually also includes: setpoint elements, actuators, measuring and transmitting elements, and comparator elements. So, what are the components of an industrial automation control system?
Based on their control principles, industrial automation control systems are classified into open-loop control systems and closed-loop control systems.
1. Open-loop control system
In an open-loop control system, the system output is only controlled by the input, resulting in poor control accuracy and interference suppression characteristics. In contrast, open-loop control systems based on time-sequential logic control are called sequential control systems; they consist of sequential control devices, sensing elements, actuators, and the controlled industrial object. They are mainly used in the control of processes in machinery, chemical engineering, material handling and transportation, as well as in robotic arms and automated production lines.
2. Closed-loop control system
A closed-loop control system is based on the feedback principle. It controls the system by utilizing the deviation between the output and the desired value, thus achieving relatively good control performance. A closed-loop control system is also known as a feedback control system.
Based on the given signal, automatic control systems can be classified into constant value control systems, servo control systems, and program control systems.
1. Constant value control system
A system whose given value remains constant, requiring the system output to approach the desired value with a certain precision. Examples of constant-value systems include automatic control systems for temperature, pressure, flow rate, liquid level, and motor speed in production processes.
2. Follow-up control system: The given value changes according to an unknown time function, and the output is required to follow the change of the given value. Such as a radar antenna system that follows a satellite.
3. Programmable control system: The given value changes according to a certain time function. Such as a programmable machine tool.
