【作者】 李斌；

【导师】 刘鲁源；

【作者基本信息】 天津大学 ， 控制理论与控制工程， 2004， 硕士

【摘要】 通过网络闭环的反馈控制系统称为网络控制系统(Network Control System，简称NCS)，它是一种完全分布式与网络化的实时反馈控制系统。不同于一般的网络系统，其传输的消息具有数据量少，传输周期短和实时性高等特点。在网络控制系统中由于所有节点共享物理传输介质，各个节点必须竞争得到网络访问权才能发送数据，基于此，必须对网络中的通信进行调度管理。本文在对近年网络控制系统的调度算法进行综述分析的基础上，基于CAN总线对网络控制系统中的调度算法进行了相关研究。首先针对网络控制系统分布式的特点，特别是类似于CAN总线的多主系统，由于没有单一的时钟提供同步机制，影响调度管理的同步。本文在“后期协商”同步算法的基础上，从减少网络同步开销，提高时钟同步的准确度与精确度的角度出发提出了“阶段分割”同步算法，该算法的采用使网络中同步消息的个数从n2+2n下降到3n，提高了带宽利用率。然后针对EDF(Earliest Deadline First)调度算法在CAN总线应用中存在的问题，研究相应的解决方案。在基本EDF调度算法的基础上提出了能够解决截止期编码的对数分区EDF调度算法。基于DM(Deadline Monotone)算法实现简单和EDF算法的灵活性强、资源利用率高等优点，提出了一种改进型EDF调度算法(简称EEDF)，有效地解决了DM调度算法资源利用率低与EDF调度算法额外开销大等缺点。 最后，基于EEDF(Enhanced Earliest Deadline First)调度算法提出了一种适用于网络控制系统的反馈控制实时调度算法FC-EEDF(Feedback Control-Enhanced Earliest Deadline First)。该调度算法针对网络控制系统的特点利用基于消息截止期的性能指标作为调节量实现反馈控制。同时在对控制理论与实时调度分析的基础上建立了一种通用的反馈调度模型，为进一步的研究奠定了基础。更多还原

【Abstract】 When a traditional feedback control system is closed via network, which is a sort of completely distributed, networked and real-time feedback control system, then the control system is called Networked Control System (NCS). Differed from the common network system, messages transmitted in the NCS have the distinct characteristic of short data length, short transmission period and high real-time. Because in the NCS physical medium is shared by all the nodes, each node having message to transmit must win the privilege of access to the medium. For these reasons the network communication should be scheduled and managed. The scheduling algorithm of NCS in CAN field bus is researched in the thesis based on the survey and analysis of the scheduling theory of NCS in several years.First, aiming at the distribution of NCS, specially the multi-master system such as CAN, there is no unified network clock, so the scheduling and management are affected. In the thesis based on the posteriori agreement from the point of reducing the message for clock synchronization and improving the precision and accuracy of network clock synchronization, the phase-decoupled algorithm is proposed. When applying the algorithm to NCS, the message for synchronization will be reduced from n2+2n to 3n.Second, based on the analysis of the problems of applying EDF algorithm to CAN, the corresponding solutions are researched. Founded on the basic EDF algorithm, the logarithmic quantization of message deadline that can solve the problem of mapping the deadline to priority is proposed. Because of the simple implementation of DM and the flexibility and the high resource utilization of EDF, a new enhanced EDF algorithm is put forward, which solves the low resource utilization of DM and the high excess resource wasting of EDF.Finally, grounded on the EEDF algorithm the feedback control real-time scheduling algorithm for NCS is proposed. In the paper the proposed algorithm aiming at the characteristic of NCS the performance index relating to the message deadline is used as adjuster. In the meanwhile based on the analysis of control theory and real-time scheduling, the general feedback scheduling model is built and established and as the basis for the future research.更多还原