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The significance of PID control
The current level of industrial automation industries to measure the level of modernization has become an important symbol. Meanwhile, the control also experienced the development of the theory of classical control theory, modern control theory and intelligent control theory of three stages. Intelligent control is a typical example of fuzzy automatic washing machine. Open-loop control system can be divided into control systems and closed-loop control system. A control system including controller, sensors, transmitters, actuators, input and output interfaces. Controller's output through the output interface, the implementing agency, added to the charged system; control system, the amount charged, through sensors, transmitters, sent to the controller through the input interface. Different control systems, sensors, transmitters, actuators are not the same. Such as pressure control system pressure sensor to be used. Electric heating control system sensor is a temperature sensor. At present, PID control and controller or intelligent PID controller (instrument) has a lot of products have been in the engineering practice has been widely applied, there is a wide range of PID controllers, the major companies have developed PID parameter self-tuning capabilities of intelligent controller (intelligent regulator), which automatically adjusts the PID controller parameters are adjusted through the intelligent or self-correction, adaptive algorithms to achieve. PID control are achieved using pressure, temperature, flow, liquid level controller, PID control can achieve programmable controller (PLC), also allows PID control of PC systems, etc.. Programmable Logic Controller (PLC) is to use the closed-loop PID control module to achieve control, programmable logic controller (PLC) can be connected directly with ControlNet, such as Rockwell's PLC-5 and so on. PID control function also allows the controller, such as Rockwell's Logix product line, which can be connected directly with ControlNet, use the network to achieve its remote control functions.
1, the open-loop control system
Open-loop control system (open-loop control system) is charged with the object output (controlled variables) on the controller (controller) did not affect the
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output. In this control system, not dependent on the amount will be charged against sending it back to form any closed loops.
2, closed loop control system
Closed loop control system (closed-loop control system) is characterized by the system control object output (controlled variables) will affect the controller against the output sent back to form one or more closed loop. Closed-loop control system has positive feedback and negative feedback, if the feedback signal and system for a given value of signal contrast, is known as negative feedback (Negative Feedback), if the same polarity is called positive feedback, the general closed-loop negative feedback control systems are used , also known as negative feedback control system. Many examples of closed loop control system. Such person is a negative feedback loop control system, the eye is the sensor, as feedback, the human system through constant correction to all the right moves last. If there are no eyes, no feedback loop, will become an open-loop control system. Other cases, when a truly automatic washing machines have to continuously check whether clothes washed, and cut off the power automatically after cleaning, it is a closed loop control system.
3, step response
Step response is a step input (step function) added to the system, the system outputs. Steady-state error is the response of the system into steady state, the system's expected output and actual output of the difference. Control system performance can be stable, accurate, fast and three words to describe. Stability is the stability of the system (stability), a system to work properly, first of all must be stable, from the step response appears to be that convergence; quasi-control system refers to the accuracy, control precision, usually stable state error to (Steady-state error) description, it said the system output and the expected steady-state value of the difference; faster control system response is fast, usually the rise time to quantify.
4, PID control principles and characteristics
In engineering practice, the most widely used regulator control law is
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PID控制的意义中英文翻译资料
