Design of Flow Control Algorithm and PID Controller for Internet-based Networked Control Systems

• Main Authors: Yu-Wei Lin, 林育暐
• Other Authors: 曾傳蘆
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/j2g3f4

碩士 === 國立臺北科技大學 === 機電整合研究所 === 94 === In recent decades, Internet has grown rapidly. Internet-based Networked Control System (INCS) which uses Internet to transmit control and feedback signals to perform closed-loop control is getting popular. However, due to the nature of uncertain transmission delay of Internet, the performance of controller designed by conventional control techniques deteriorates. Based on the Control System Transfer Protocol (CSTP), this thesis proposes a new flow control algorithm to solve the problem. The proposed algorithm also improves the efficiency of TCP-Like flow control algorithm. Using the monitored network states, round trip time (RTT) and the change of RTT, a fuzzy logic reasoning mechanism is proposed to adjust the packet sending rate of the sender and thus the packet transmission delay is reduced. Moreover, using the error response of the considered INCS, a GA-based PID controller is designed at the client to improve the capability of traditional PID controller. Finally, the research builds up an INCS environment as a testing platform by the VisSim and VB software to verify the performance of the proposed method. From the experimental results, it is seen that the method proposed by this thesis can reduce the influence of network transmission environment and performs well in the presence of time delay.