A New Type Of Embedded PAC Controller Design And Key Technology Researh

There is an increasing demand of controlling in the industrial manufacturing process. PAC is a new type of programmable automation controller, which has significant advantages on controlling performance, information processing, data acquisition and network communication capabilities.PAC brings in various advantages of PLC and PC. PAC has the features of stable reliability, easy operation and real-time processing performance.PC machine has the capabilities of powerful computing, data storage and processing, mature network communication, graphic images display, and databases as well as third-party applications communications.The research on embedded PAC controllers has been carried out at home and abroad. But the domestic research on PAC controller is relatively late, which mainly refers to ICPDAS in Taiwan and Yan Hua in Mainland China. A new embedded PAC controller is designed in the paper, which has the features of high control precision, strong compatibility, rich communication capabilities, and low cost. It is suitable for a variety of industrial control occasions. On the control algorithm, it improves the PID control algorithm, PID relay-feedback self-tuning algorithm, and fuzzy-PID self-tuning. The PAC controller can improve control accuracy and control response, to meet the higher control requirements.The main work is as follows:(1) The researcher designed and developed a lightweight embedded PAC controller hardware platform, which adopted a high performance microcontroller, equipped with the embedded operating system. The platform can realize input sampling and output controlling of multi-channel analog quantity and digital quantity, and integrated RS232, RS485, CAN bus, Ethernet bus and other communication technology, and realize the coordinated control of a variety of controllers.(2)The software design is based on embedded PAC controller hardware platform, and transplanted embedded operating system and embedded TCP / IP protocol stack to the hardware platform. On the basis of high-precision input sampling and output control, the PAC controller using the common protocols of Modbus-RTU and Modbus-TCP to design and develop communication software, and build in Web-Server, and finally developed and designed Lab VIEW PC software for remote acquisition and control.(3)It is commonly used PID algorithm in the industry. The research improved PID algorithm, analyzed the self-tuning PID algorithm, and implemented the relay feedback self-tuning PID algorithm in embedded systems. The experimental results show that the parameters which measured by the method can basically meet the control requirements.(4)For more industrial control equipment, such as pulsation vacuum sterilizer, pipeline electric heating oil, reactor kettle and other control objects, which have characteristics of nonlinear, time-varying, time-delay. It hasn't been able to meet higher control requirements for only using PID control. Integrated by fuzzy control algorithm with PID control, the researcher designed a fuzzy self-tuning PID control algorithm. Experiments show that this method improves the control performance, and has very good control effect.