tailieunhanh - Advanced Control Engineering - Chapter 7

Digital control system design Như một kết quả của sự phát triển trong công nghệ bộ vi xử lý, việc thực hiện của thuật toán điều khiển bây giờ là lúc nào thông qua việc sử dụng vi điều khiển nhúng hơn là sử dụng các thiết bị tương tự. Một hệ thống điển hình sử dụng bộ vi xử lý kiểm soát được hiển thị trong hình . Trong hình . RAM là bộ nhớ truy cập ngẫu nhiên và được sử dụng cho không gian làm việc mục đích chung. ROM, PROM, EPROM là đọc bộ nhớ. | 7 Digital control system design Microprocessor control As a result of developments in microprocessor technology the implementation of control algorithms is now invariably through the use of embedded microcontrollers rather than employing analogue devices. A typical system using microprocessor control is shown in Figure . In Figure RAM is Random Access Memory and is used for general purpose working space during computation and data transfer. ROM PROM EPROM is Read Only Memory Programmable Read Only Memory and Erasable Programmable Read Only Memory and are used for rapid sources of information that seldom or never need to be modified. A D Converter converts analogue signals from sensors into digital form at a given sampling period T seconds and given resolution 8 bits 16 bits 24 bits etc. D A Converter converts digital signals into analogue signals suitable for driving actuators and other devices. The elements of a microprocessor controller microcontroller are shown in Figure . Figure shows a Central Processing Unit CPU which consists of the Arithmetic Logic Unit ALU which performs arithmetic and logical operations on the data and a number of registers typically Program Counter - incremented each time an instruction is executed Accumulator s - can undertake arithmetic operations Instruction register - holds current instruction Data address register - holds memory address of data Control algorithms are implemented in either high level or low level language. The lowest level of code is executable machine code which is a sequence of binary words that is understood by the CPU. A higher level of language is an assembler which employs meaningful mnemonics and names for data addresses. Programs written in assembler are rapid in execution. At a higher level still are languages Digital control system design 199 Fig. Microprocessor control of a plant. program counter RAM address bus accumulator s ALU instruction register data bus ----- ROM PROM EPROM data