《工业现场总线协议的建模与仿真分析》由会员分享，可在线阅读，更多相关《工业现场总线协议的建模与仿真分析（99页珍藏版）》请在金锄头文库上搜索。
1、 I工业现场总线协议的建模与仿真分析 摘摘 要要 工业现场总线控制系统 FCS 是计算机、通信、仪表和控制技术相结合的产物，适应了工业控制系统的分散化、网络化和智能化的要求，已成为控制技术研究领域的热点。但现在现场总线的研究却不能很好地满足实际工程的需要，很多具有挑战性的问题急迫需要解决。同时现场总线研究工具功能的局限性也在很大程度上制约了其研究工作的开展。本文从现场总线的研究工具入手，在网络通信协议层面上对现场总线进行了研究和探索。本文的主要工作和贡献如下： 1. 首先针对工业控制领域的发展，介绍了应用日益广泛的现场总线，总结了现场总线的特点和实时性要求。通过对现场总线通信协议及其研究现状的
2、分析，指出了现场总线研究方面存在形式化描述不足的问题，提出了结合 Petri 网和 Matlab 强大功能的新型研究方法。 2. Petri 网作为图形化的数学建模工具，已被广泛用来描述和分析复杂通信协议。而目前专门针对 Petri 网设计的仿真软件大都是非商业性的，仿真能力有限。Matlab 作为一种工程计算及系统仿真等方面的大型商业软件，在仿真能力、扩展性及服务支持上有着明显的优势。为此，提出了一种利用 Matlab/Stateflow 对 Petri 网模型进行仿真的方法。 3. 在具体介绍了 FF 总线的基础上，建立了该协议的 DSPN 模型，运用II介绍的方法建立了 FF 总线协议在
3、 Matlab/Stateflow 下的仿真平台模型，并运用该模型对总线性能进行了仿真分析。 针对 FF 总线协议中调度表的构造问题，介绍了单调速率算法。同时针对该算法的不足，引进了 ERM算法，并给出了 ERM 算法的可行性分析。 4. 在具体介绍了 CAN 总线协议的基础上，建立了该协议的 DSPN 模型和 Matlab/Stateflow 下的仿真平台模型。 并运用该模型对总线性能进行了仿真分析。为保证 CAN 总线中信息传输的严格实时性,引入了 TDMA 调度机制,并且混合了 EDF 调度算法来调度软实时信息。 该混合算法通过给硬实时信息保留特定时间域的方法,来满足硬实时信息的严格实时
4、性要求，该算法可以充分保证系统信息的实时性要求。 5. 具体介绍了一种新型总线协议FTT-CAN 协议。引进了一种保证后备主节点和活动主节点运行完全同步的方法, 并用状态机进行了描述。根据 FTT-CAN 总线的特点，建立了其 DSPN 模型和对应的Matlab/stateflow 仿真平台模型，并运用该模型对总线性能进行了仿真分析。在 FTT-CAN 中,由于错误可能导致后备节点需要在线更新 SRT 表以达到和活动主节点完全一致，而协议中并没有保证后备节点 SRT 表更新的相关机制。 为此本文提出了一种保证后备节点SRT表更新过程的算法。同时在充分考虑了更高优先级突发信息的影响后，对算法进行
5、了简化，以适合在线实时调度的需要。最后，对该算法进行了仿真和分析。 关键词关键词： 现场总线系统，Petri 网，模型，网络调度 IIIMODELING、SIMULATION AND ANALYSIS OF FIELDBUS PROTOCOLS ABSTRACT Fieldbus Control System(FCS), which is nurtured from computer, telecommunications, instruments and control technologies meets the requirement of automatic control syste
6、m for distribution, network and intelligent, and has been the hotspot of global automation technology. However, the academic study of Fieldbus cant meet the actual needs and there are many challenging issues need to be addressed urgently. Meanwhile the limitations of instruments have largely restric
7、ted the development of the research in FCS. This dissertation starts the researching work from the instruments and focuses on the network communication protocols to study and explore the FCS. The main work and contributions of this dissertation can be summarized as follows: 1. First, as to the devel
8、opment in the field of industrial control, the dissertation introduces and summarizes the characteristics of FCS. From the analysis of communication protocol and the present researching achievement of FCS, this dissertation points out the problem that modal description of IVFCS is not enough now, an
9、d provides a new researching method which combined the great functions of Petri Net and Matlab. 2. As a modeling tool for graphic mathematics, Petri Net has been widely used to describe and analyze complicated communication protocols. But now, the specifically designed simulation tools for Petri Net
10、 are all non-commercial and their simulation capacities are limited. Meanwhile Matlab as a large commercial software has been widely used in systems engineering and simulation. It has obvious advantage in simulation capability, expansibility and support services. Therefore, a method how to use Matla
11、b/Stateflow to simulate the Petri Net is presented. 3. After a specific introduction of FF protocol, its DSPN model and the corresponding Matlab/Stateflow model are established by the method previously provided. And the performance of FF protocol is simulated and analyzed on the model. As to the con
12、struction of FF scheduling table, the Rate Monotonic algorithm is provided. Also, the Extended Rate Monotonic algorithm and its feasibility analysis algorithm are provided to mend the disadvantage of RM algorithm. 4. After a specific introduction of CAN, its DSPN model and Matlab/Stateflow model are
13、 established, and the performance of CAN protocol is simulated and analyzed on the model. To guarantee the strict Vreal-time requirement of information in CAN, the TDMA scheduling mechanism is introduced, and the EDF scheduling algorithm is also introduced to regulate the soft real-time information.
14、 The hybrid algorithm guarantees the stringent requirement of hard real-time information by the method that reserves the specific time domain for it. The hybrid algorithm can fully guarantee the stringent time requirement of system information. 5. As a new protocol, FTT-CAN is described in detail. A
15、 method to guarantee the synchronized activities between backup and active master nodes is presented and described by the state machine. The DSPN model and the Matlab/Stateflow model of FTT-CAN are established, and its performance is simulated and analyzed on the model. Due to errors in FTT-CAN, the
16、 backup nodes may need to update their SRT tables to achieve synchronization with active master, but there is no mechanism to guarantee the updating process. So an algorithm to guarantee the SRT updating process of backup nodes is presented in this dissertation. And the algorithm is simplified after carefully consideration of the influences of higher priority packages to meet the needs of online real-time scheduling. Finally, the algorithm is simulated and analyzed on the simulation platf
