《自控理论ch7》由会员分享，可在线阅读，更多相关《自控理论ch7（138页珍藏版）》请在金锄头文库上搜索。
1、Automatic Control Theory Chapter 7 School of Information Science and Engineering,CSUAutomatic Control TheorySchool of Information Science and Engineering,CSU*Automatic Control Theory Chapter 7 School of Information Science and Engineering,CSUChapter 7 Analysis and Compensation of Linear Discrete-tim
2、e System7.1 Basic concept of discrete-time system7.2 Sampling and holding of signal7.3 z transform theory7.4 Mathematic model of discrete-time system7.5 Stability and steady-state error Summary7.6 Transient-state performance analysis7.7 Digital compensation of discrete-time system 7.8 Design of disc
3、rete-time control systemAutomatic Control Theory Chapter 7 School of Information Science and Engineering,CSU7.1 Basic concept of discrete-time system7.1.1 Sampling control system7.1.2 Digital control system7.1.3 Characteristic of discrete-time system7.1.4 Research method ReturnAutomatic Control Theo
4、ry Chapter 7 School of Information Science and Engineering,CSU7.1.1 Sampling control system1. Concept of discrete-time systemThe signals in system include impulse sequence or digital, the system can be called discrete (time) system. Generally, if the discrete signal is impulse sequence, the system i
5、s called sampling system or impulse control system. If the discrete signal is digital, the system is called digital control system or computer control system(The systems controller is digital computer at almost time). Automatic Control Theory Chapter 7 School of Information Science and Engineering,C
6、SUExample: Furnace temperature control systemAutomatic Control Theory Chapter 7 School of Information Science and Engineering,CSU2. Sampling signal Period sampling (sampler)T is sampling period.Ideal sampler =0Real samplerAutomatic Control Theory Chapter 7 School of Information Science and Engineeri
7、ng,CSUSampling signal reconstrutingHolderAutomatic Control Theory Chapter 7 School of Information Science and Engineering,CSU3. Typical structure diagram of sampling systemSamplerHolderPlantSensorReturnAutomatic Control Theory Chapter 7 School of Information Science and Engineering,CSU7.1.2 Digital
8、control systemA digital computer may serve as a compensator or controller in a feedback control system. Since the computer receives data only at specific intervals, it is necessary to develop a method for describing and analyzing the performance of computer control systems.Automatic Control Theory C
9、hapter 7 School of Information Science and Engineering,CSUComputer control systems are widely used in industry. They also play an important role in the control of industrial processes which utilize a combination of a computer and an actuator working together to perform a series of tasks.Automatic Co
10、ntrol Theory Chapter 7 School of Information Science and Engineering,CSU1. Digital control systemTypical diagram of computer control systemAutomatic Control Theory Chapter 7 School of Information Science and Engineering,CSUDigitizationIf we have designed a continuous-time (analog) controller and wis
11、hed to implement it digitally, we need analog-to-digital (A/D) converter, digital-to-analog (D/A) controller and processor (computation of control action). In addition, sometimes we also need an filter before sampling.Automatic Control Theory Chapter 7 School of Information Science and Engineering,C
12、SU2. A/D converter Continuous analog signalDiscrete digital signal1) Sampling: e(t) e*(t)2) Quantization量化: e*(t) Automatic Control Theory Chapter 7 School of Information Science and Engineering,CSU3. D/A converterContinuous analog signalDiscrete digital signal1) Decoding解码;2) Reconstructing复现(重构).A
13、utomatic Control Theory Chapter 7 School of Information Science and Engineering,CSU4. Typical block diagram of digital control systemTTAutomatic Control Theory Chapter 7 School of Information Science and Engineering,CSUControl principleThe digital computer receives the error in the digital form and
14、performs calculations in order to provide a control output in digital form. The computer may be programmed to provide the output control signal so that the performance of the process is near or equal to the desired performance. Many computers are able to receive and manipulate several inputs, so a d
15、igital computer control system can often be a multivariable system.ReturnAutomatic Control Theory Chapter 7 School of Information Science and Engineering,CSU7.1.3 Characteristic of discrete-time system1. A digital computer may serve as a compensator or controller in control system. The effect is better than analog compensator. The control rule can be modified conveniently and is very agile.2. Transfer of sampled signal (digital signal) can effectively reduce noise, so
