Research On Networked Control System Performance Based On Improved EDF Scheduling Strategy

Networked control system is a new comprehensive application involving computer technology,communication network and control science.Traditional control theories and methods have become more and more difficult to meet the needs of actual work with the increase of control objects and the complexity of the control environment.The networked control system is widely used in intelligent robots,industrial control,aerospace and military industries due to its advantages of resource sharing,easy management,high security and good reliability.At the same time,as a technology produced by the integration of multiple disciplines,many new problems have also appeared,such as channel execution delay,transmission congestion,and data packet loss.The competition for resources in the task of network transmission gives new directions and meanings to the research work.The competition for resources in the network transmission of tasks gives new directions and meanings to the research work.The central task of this dissertation is how to improve and optimize the execution effect of the tasks in the network control system,optimize the transmission quality and improve the adaptability to the task of dynamic changes of attributes,and maintain the stability of the control system.The research of this dissertation mainly includes the following aspects:(1)This dissertation introduces the current research direction and existing problems of networked control system,introduced the basic concepts of networked control system scheduling,classified the scheduling methods and described their typical scheduling strategies in detail,and analyze the characteristics,advantages and disadvantages of static and dynamic scheduling.(2)This dissertation explains the transmission protocols under different networks,and builds a simulation platform to verify the working effects of different scheduling strategies and different network protocols,determines the best network environment and protocol suitable for task transmission in the networked control system.(3)Considering that the overall performance of the networked control system is closely related to the time attribute of the transmission task and the channel environment.This dissertation makes improvements on the basis of the EDF(Earliest Deadline First)scheduling strategy.Starting from the schedulable condition,the task dynamic change time interval is refined,and the distribution function of each attribute is used to obtain the distribution function of the schedulable condition based on two judgments rules are the conditions of possibility and necessity,finally the precise values of the schedulable variables that meet the requirements is determined and the precise execution time and period values of the task attributes are obtained.On this basis,task transmissions under different packet loss rates and interference rates are carried out.The defect of performance degradation caused by the indefinite priority under the traditional method is overcome,the system output quality is enhanced,and the adaptability to adverse influence factors is improved at the same time.(4)Considering that the traditional control method in the networked control system cannot dynamically adjust its properties with the environment,the traditional PID controller is optimized in this dissertation.A fuzzy PID controller fused with fuzzy control theory is designed,and data transmission is carried out based on the improved EDF scheduling strategy.Through the dual optimization of the scheduling algorithm and the controller,the reasonable allocation of resources in the task execution process is realized,the problems of invalid competition and information congestion are reduced,and the performance of the networked control system is further improved.The multi-loop task model of the networked control system is established in this dissertation,the task transmission under the improved EDF scheduling strategy is also simulated and verified.It is proved that this method can effectively improve the adaptability of tasks under dynamic changes in execution time and period,enhance the transmission quality of tasks and maintain good system stability.