What does a control system consist of? A management system with its own goals and functions.

The control system is a management system with its own goals and functions composed of "control subject", "control object" and "control media". Control system means by which any interesting or variable quantity within a machine, mechanism or other device can be maintained and changed in a desired manner. In order to realize the basic tasks of automatic control, requirements must be put forward for the behavior of the system during the control process; the basic requirements for the control system are usually met by the system's response to specific input signals.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

The control system refers to the management system with its own goals and functions composed of control subject, control object and control media .

Control system means by which any interesting or variable quantity within a machine, mechanism or other device can be maintained and changed in a desired manner. The control system is also implemented to make the controlled object reach a predetermined ideal state. The control system brings the controlled object to a certain required stable state.

For example, consider a drive system for a car where the speed of the car is a function of its accelerator position. The desired speed can be maintained (or the desired speed change can be achieved) by controlling the pressure on the accelerator pedal. This car drive system (accelerator, carburetor and engine vehicle) forms a control system.

Classification

• Classification according to whether there is feedback

  • No feedback is called an open-loop control system (open-loop control system), the input of this system is directly supplied to the controller, and the controlled object is controlled through the controller. Its main advantages are simple structure, low price, and easy maintenance; its disadvantages are low accuracy and easy to be interfered by environmental changes (such as power supply fluctuations, temperature changes, etc.).

  • Having feedback is called a closed-loop control system. The difference between the input signal and the feedback signal (ie, the deviation signal) is added to the controller, and then the controller is adjusted. The output of the controlled object forms a closed-loop control loop. Therefore, the closed-loop system is also called a feedback control system, and this feedback is called negative feedback. Compared with open-loop systems, closed-loop systems have outstanding advantages, including high accuracy, good dynamic performance, and strong anti-interference ability. Its disadvantages are that the structure is relatively complex, the price is relatively expensive, and it requires high maintenance personnel.

• Different classifications based on the signal processing technology used

  • Analog control system, a control system that uses analog technology to process signals It is called an analog control system.

  • Digital control system, a control system that uses digital technology to process signals is called a digital control system.

• Classification according to whether the input quantity is constant

  • The input quantity is constant, we generally call this control system It is a constant value control system, such as constant speed motor, constant temperature furnace, etc.

  • The output quantity changes as the input quantity changes. This kind of control system is called a follow-up system. For example, missile automatic aiming system, etc.

Performance requirements

In order to achieve the basic tasks of automatic control, it is necessary to control the performance of the system during the control process. Behavior makes demands. The basic requirements for a control system are usually met by the system's response to specific input signals. For example, it is represented by the transition process of the unit step signal and some characteristic values ​​of the steady state. On the premise of ensuring stability, the system is required to have good dynamic performance and steady-state performance, that is:

• The dynamic process is stable (stability);

• The response action must be fast (rapidity);

• The tracking value must be accurate (accuracy).

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