计算机控制系统(英文版)Chapter1ComputerControlTheoryandDesign

Computer-Controlled Systems Theory and Design,2,Course Information,Time: 10:00-11:40am, Friday 10:00-11:40pm, Tuesday (even weeks) Office hour:10:00-11:40,Tuesday (odd weeks), 622 Venue: 综A209 Modules + Experiments Grading Procedure: in-term evaluation experimental results final paper examination. Important Formula: Success=Hard Work + Good Luck,3,Chapter 1 Computer Control,4,Contents,1.1 Introduction to CCS 1.2 Classification of CCS 1.3 History and future of CCS 1.4 Computer-control theory 1.5 Summarization,New Words,5,New Words,6,New Words,7,8,1.1 Introduction,Comparison between ACS and CCS,9,1.1 Introduction,A typical computer-controlled system,Figure 1.1: Schematic diagram of a computer-controlled system,Synchronization,a sequence of numbers,10,1.1 Introduction,ACS CCS,Structure:,Process Actuator Measure Controller (correcting network),Process Actuator Measure Controller (digital computer) Adapter (A/D, D/A),Parts:,Analog Analog + Digital,Signals:,Analog,Continuous analog Discrete analog Discrete digital,11,1.1 Introduction,Virtues Strong computation ability for realizing complex control algorithms, which are easily modified High precision:10-70 (analog: 10-2) High volume memory: store a great deal of information Adaptive and robust: self-learning and reasoning High efficiency: multi-control loop ( analog: one ) Defects Error: quantization error Computation delay: especially for serial computation and complex control algorithms,12,1.2 Classification,1.2.1 Operation Guide Control System,Open-loop control system Simple, safe, reliable For design, tuning For data collection and handle,13,1.2 Classification,1.2.2 Direct digital control (DDC),Close-loop control system Multi-control algorithms Instead of multi-analog controllers to control multi-loops simultaneously,14,1.2 Classification,1.2.3 Supervisory computer control (SCC),Upper computer control + lower computer control (analog or digital) Upper computer: high-level control and management for set point control, sequential control and optimal control Lower computer: control the process,15,1.2 Classification,1.2.4 Distributed control system (DCS),DCC: for process SCC: coordinate and supervise DCCs for shops optimal control Factory level: make plan for the factory and report the data of SCCs and DCCS Management level: make long- term plan, coordinate the full company and global optimization,16,1.3 History and Future,1952-1965: pioneering period Thomson Ramo Woodridge and Texaco: a computer-controlled system for the polymerization unit for a refinery factory in Texas was designed 1965-1972: industry application period Minicomputer Computer central control,17,1.3 History and Future,1972-: development period Microcomputer Period and General Use of Computer Control PLC (Programmable logic controller) Distributed control system Computer integrated system Embedded system Network control system,18,1.3 History and Future,19,1.3 History and Future,The future of the technology related to CCS process knowledge Continuous increasing process knowledge with slow speed Process control system measurement technology Data merging Soft measurement computer technology Computation ability, visualization, communication programming control theory Model predictive control, adaptive control More difficult control algorithm,20,1.4 Computer-Control Theory,Approximations of analog control system (ACS): CCSACS 1.4.1 Time dependence 1.4.2 A naive approach to CCS 1.4.3 Deadbeat control 1.4.4 Aliasing 1.4.5 Difference Equation,21,1.4 Computer-Control Theory,1.4.1 Time Dependence Example1.1 Time dependence in digital filtering Figure 1.4(a) The block diagram of a digital filter.,22,1.4 Computer-Control Theory,23,1.4 Computer-Control Theory,Phenomena: The figure clearly shows that the sampled system is not Time-invariant because the response depends on the time when the step occurs. Conclusion: The response of the system to an external stimulus will then depend on how the external event is synchronized with the internal clock of the computer system. The closed-loop system is a linear periodic systems.,24,1.4 Computer-Control Theory,1.4.2 A naive approach to CCS Example1.2 Controlling the arm of a disk drive A schematic diagram of a disk-drive assembly is shown in Fig. 1.5.,25,A Hard disk Drive System,1.4 Computer-Control Theory,26,1.4 Computer-Control Theory,27,1.4 Computer-Control Theory,28,1.4 Computer-Control Theory,Phenomena: When sampling period is very small, the difference between the outputs of the systems is very small. When sampling increases, the CCS will deteriorate. Conclusion: It is straightforward to obtain an algorithm for CCS simply by writing the continuous-time control law as a differential equation and approximating the derivatives by differences.,29,1.4 Computer-Control Theory,1.4.3 Deadbeat control Example 1.3 Disk drive with deadbeat control,30,1.4 Computer-Control Theory,Phenomena: The excellent behavior of the