Classification of computer control systems \ x0d \ x0d \ There are three methods to classify computer control systems: automatic control line classification, participation control method classification or regulation law classification. \x0d\ 1。 Classification by automatic control line \ x0d \ x0d \ can be divided into the following categories by automatic control: \ x0d \ (1) computer open-loop control system \ x0d \ x0d \ If the output of the computer open-loop control system can control the production process, but the control result-the state of the production process does not affect the computer control system, and the computer \ controller. As can be seen from the figure, the state of the production process is not fed back to the computer, but the operator monitors the state of the production process, decides the control scheme, and tells the control computer to exercise its control function. \ x0d \ x0d \ (2) Computer closed-loop control. X0d\\x0d\ Computer control system is called computer-controlled closed-loop control system. When the computer controls the production object or process, the state of the production process can directly affect the computer. Under the supervision of the operator, the control computer automatically accepts the detection results of the production process state, calculates and determines the control scheme, directly directs the actions of the control elements (devices) and controls the production process. \ x0d \ x0d \ In such a system, the control part controls the running equipment according to the control information sent by the control machine, and on the other hand, the running state of the running equipment is taken as the output, which is measured by the detection part and fed back to the control computer as the input; So that the control computer, the control part, the production process and the detection part form a closed loop. We call this control form control computer closed-loop control. \ x0d \ x0d \ The computer closed-loop control system uses the mathematical model to set the deviation between the optimal value of the production process and the feedback value of the test results, so as to control the production process to run in the optimal state. \ x0d \ x0d \ (3) Online. As long as the computer can directly control the controlled object or the controlled production process, it is called online control of the control computer or online control system without manual intervention. \x0d\\x0d\ (4) Off-line control \ x0d \ x0d \ The control computer does not directly participate in the controlled object or the controlled production process. It only completes the state detection of the controlled object or process, and processes the detection data; Then, the control scheme is formulated and the control instruction is output. The operator refers to the control instruction and manually operates the control part to control the controlled object or the controlled process. This control form is called computer off-line control system. \ x0d \ x0d \ (5) Real-time control system \ x0d \ x0d \ Control computer Real-time control system refers to the controlled object or process. Whenever processing or control is required, another example is the rolling process, in which each rolled steel is counted as a process and each process is repeated. Computer control is only required when entering the process. Once the computer is controlled, it is required to respond or control the information from the production process within a specified time. This system is often realized by using a perfect interrupt system and interrupt handler. To sum up, an online system is not necessarily a real-time system, but a real-time system must be an online system. \ x0d \ x0d \ II。 \ x0d \ x0d \ can be divided into the following categories according to the participating control mode: \ x0d \ (1) Direct digital control system \ Actually, the control part of the controlled production process can convert the digital control quantity output by the computer into analog quantity through the D/A converter in the process input/output channel of the controller. The input analog quantity should also be converted into digital quantity through the A/D converter of the process input/output channel of the controller and enter the computer. \ x0d \ x0d \ DDC control system often adopts microcomputer or microcomputer time-sharing system to realize multi-point control function. In fact, it belongs to discrete sampling with controller. And realize discrete multipoint control. This DDC computer control system has become one of the main control forms of computer control system at present. \ x0d \ x0d \ DDC control has the advantages of great flexibility, high centralized reliability and low price. The production process of several loops, even dozens of loops, can be controlled by proportional-integral-differential (PID) in the form of digital operation, so that the state of industrial controlled objects can be maintained at. The deviation is small and stable. Moreover, as long as the control algorithm and application program are changed, more complex control, such as feedforward control and optimal control, can be realized. Generally speaking, DDC level control is often used as the executive level of more complex advanced control. \ x0d \ x0d \ (2) Computer monitoring system \ x0d \ x0d \ Computer monitoring system is aimed at a certain production process, according to various states of the production process, according to the mathematical model of the production process, to calculate the optimal given value of the production equipment, and automatically or manually adjust the optimal value to the DDC executive level computer or analog regulating instrument or set the control target value. DDC or regulating instruments control all points (operating equipment) in the production process. \ x0d \ x0d \ SCC system is characterized by ensuring that the controlled production process is always in the best state. Therefore, the maximum benefit can be obtained. The first thing that directly affects the effect of SCC is its mathematical model. Therefore, it is necessary to constantly improve the mathematical model and modify the control algorithm and application control program accordingly. \ x0d \ x0d \ (3) Multi-level control system \ x0d \ x0d \ In modern production enterprises, we should not only solve the online control problem of production process, but also solve the production management problem. Daily production variety and quantity planning and scheduling, as well as rose planning, making long-term plans and forecasting sales prospects. , so there is a multi-level control system. \ x0d \ x0d \ DDC level is mainly used to directly control the production process and carry out PID or feedforward control; SCC level is mainly used for optimal control or adaptive control or self-learning control calculation, guiding DDC level control and reporting to MIS level. Generally, the DDC level uses a microcomputer, and the SCC level generally uses a small computer or a high-grade microcomputer. The main function of \ x0d \ x0d \ MIS in workshop management is to make reasonable production scheduling at any time according to the orders of production varieties and quantities issued by the factory level and the collected production process status information. Achieve optimal control and direct SCC level supervision and control. \ x0d \ x0d \ The main function of the factory management MIS is to accept the production tasks assigned by the company and the actual situation of the factory, make optimization calculation, make the production plan and short-term (ten-day, week or day) arrangement of the factory, and then assign the production tasks to the workshop level. The main function of \ x0d \ \ x0d \ MIS in the management of the company is to predict and calculate the market demand. Make a strategic long-term development plan, compare and choose the best production plan according to the order contract, raw material supply and the production situation of the enterprise, make a long-term (monthly or ten-day) production plan and sales plan for the whole company and the whole enterprise, and assign tasks to all management levels of the factory. The main function of \ x0d \ x0d \ MIS layer is to realize real-time information processing, provide useful information for decision makers at all levels, and formulate production planning \ scheduling management scheme to make planning coordination management in an optimal state. This level can be divided into several levels according to the size and management scope of the enterprise. Each level determines the type of computer to be used according to the amount of information to be processed. General workshop-level MIS uses small computers or high-grade microcomputers, factory-level MIS uses medium-sized computers, and company-level MIS uses large computers or super-large computers. X0d\\x0d\ (4) Distributed control or decentralized control system \x0d\\x0d\ Distributed control is to divide the control system into several independent local control subsystems to complete the automatic control task of the controlled production process. Due to the appearance and rapid development of microcomputer, it provides a material and technical basis for realizing decentralized control, and decentralized control has developed abnormally in recent years. It has become an important trend in the development of computer control. \ x0d \ x0d \ Since 1970s, centralized and decentralized control system has appeared, which is a new computer control system with decentralized local control. \x0d\\x0d\ III。 Classify according to laws and regulations \ x0d \ x0d \ If classified according to laws and regulations, computers are very important to industry. X0d\ (1) program control \x0d\\x0d\ If the computer control system is controlled according to a predetermined time function, this control is called program control. If the furnace temperature is controlled according to a certain time curve, it is called program control. The program here refers to the program that determines the corresponding change value with time change, not the running computer. \ x0d \ x0d \ (2) On the basis of program control, sequential control is generated. If the computer can control the production process according to the corresponding values determined with time and the control results before this moment, it is called computer sequential control. \x0d\\x0d\ (3) Proportional integral differential PID control can be used to control conventional analog regulating instruments. PID control can also be realized by microcomputer. \ x0d \ \。 (4) Feedforward control \ x0d \ x0d \ In the usual feedback control system, only when the interference has certain consequences can the feedback produce the control effect of restraining the interference, thus producing the adverse consequences of lagging control. In order to overcome this bad control, after the computer receives the interference signal, a feedforward control effect is inserted before the consequences, so that the influence of the interference on the control variables at the interference point can be completely offset. Therefore, it is also called disturbance compensation control. \x0d\\x0d\ (5) Optimal control system \ x0d \ x0d \ A control system is called an optimal control system. If the computer control system is adopted, the control law (mathematical model) is properly selected under the existing restrictions, so that the operating index of the controlled object is in the best state. The optimal state is determined by a given mathematical model, sometimes it is to pursue a single optimal index in a limited range, and sometimes it is to require a comprehensive optimal index. \x0d\\x0d\ (6) Adaptive control system \x0d\\x0d\ The above-mentioned optimal control can not achieve the best control effect when the working conditions or limiting conditions change. If the working conditions change, the control system that can still control the controlled object is in the best state. Such a control system is called an adaptive system. This requires a mathematical model to reflect how to achieve the best state when conditions change. The control computer detects the information of condition change, calculates according to the rules given by the mathematical model, and changes the control variables, so that the controlled object can still be in the best state. \ \x0d\\x0d\ (7 7) Self-learning control system \x0d. X0d\ If the computer can continuously accumulate experience according to the operation result of the controlled object, and change and improve the control law by itself, so that the control effect is getting better and better, such a control system is called a self-learning control system. \ x0d \ x0d \ The above-mentioned optimal control, adaptive control and self-learning control all involve multi-parameter and multi-variable complex control systems, and they all belong to the research problems of modern control theory. The judgment of system stability, the study of complex mathematical models affected by various factors, etc. It must be realized through the cooperation of production management, production technology, automatic control, testing instruments, program design and computer hardware. The computer scale is determined by the response time required by the controlled object, the number of control points and the complexity of the mathematical model. Generally speaking, it needs a computer with strong functions (speed and calculation function) to realize it. \x0d\\x0d\ The above various controls can be single or not, and several forms can be combined to control the production process. This should be determined in system analysis and system design according to the actual situation of the controlled object.