Study on Dynamic Priority Scheduling Based on Fuzzy Logic for Networked Control Systems

Based on the analysis of major factors that influence networked control systems (NCSs) communication scheduling, a dynamic priority scheduling scheme based on fuzzy logic is presented. In the scheme, the communication priority is determined by 3 factors, which are the message deadline, the performance criterion and the parameter error of control loops. Experiments of medium access control (MAC) with CAN bus prove that the proposed dynamic priority scheduling can satisfy real-time demands of different control loops under heavy burden of network, and improve the network utilization efficiency and NCSs' performance.

I. Introduction

Along with the fast development of computer and network communication, the structure of control system is changed a lot. The Networked Control Systems (NCSs), a new combination of network and computer control technology, become a hot topic in academia. Because the traditional point-to-point links are replaced with networked communication in NCSs, a higher reliability is achieved here, and NCSs are easy in installation, system diagnosis and maintenance. Meanwhile, NCSs can reduce the cost and improve the flexibility of control systems. But, the limited bandwidth and carrying capacity of network are shared by a few of control loops, thus there are some problems such as network-induced delay and Jitter, and these problems will bring the systems dynamic performance decline even stability comedown, and increase the complexity of control system analysis and design.