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随着控制规模的扩大和以太网技术在工业中日益广泛的应用，基于以太网的网络化控制系统成为控制界发展和研究的热点。本文结合基于以太网的现场网络化控制系统的研究和开发，对基于以太网的网络化控制系统的实时性进行研究，着眼于在资源有限和成本约束下，提高网络化控制系统的实时性和可实用性，并将其应用到研究开发的NetCON系统中。 论文的主要研究内容和创新之处如下： ⑴ 详细介绍了网络化控制系统（NetCON）的构建过程，对各个子系统的关键技术点进行了说明，然后结合以太网的应用特性，对NetCON系统在实时应用中所面临的问题进行了分析，指出网络控制节点的内部时延决定了NetCON系统的整体实时性，并确定了影响节点内部时延的三个关键因素：微处理器、操作系统和节点内部的网络传输延时，它们相应也是改善NetCON系统的实时性的切入点。 ⑵ 操作系统是影响控制节点内部延时的主要因素，为提高NetCON系统的实时性，选择基于最新的2.6内核的嵌入式Linux作为了控制节点的新一代操作系统，因为2.6内核与2.4内核相比，不仅支持了内核可抢占的调度策略，而且采用了更小的调度周期，因此在实时性能上有了很大提高。在此基础上，完成了NetCON系统向2.6内核升级的相关工作，包括设备驱动程序开发、相关服务程序移植和基于实时进程的应用程序开发等。 ⑶ 根据控制系统中常伴随有大量的复杂浮点运算存在的实际情况，选择了带浮点运算协处理器的ARM9芯片EP9302作为NetCON系统中网络控制节点的CPU单元，然后结合浮点运算协处理器的使用特点，对NetCON系统的实现机制进行了相应修改，完成了NetCON系统的硬件控制器从AT91RM9200到EP9302微处理器的升级工作，包括设备驱动的开发，交叉编译与下载机制的改进等，实例测试表明，新NetCON系统在应用于有大量运算的复杂应用时，实时性能有了明显提高。 ⑷ 在网络化控制系统中，各种数据信息的传输实时性要求并不相同，根据这一特点，论文利用Qos控制在NetCON系统中实现了数据的分类传输调度机制，根据数据的实时性来分配带宽和传输优先级，这样各个控制节点在数据传输过程中将优先保证实时数据的传输，以此提高系统的整体实时性。另外，根据网络化控制系统中实时数据一般具有速率高、数据包长度相对较短的特点，论文采用了NAPI技术来提高NetCON系统的网络处理速度，这也是提高NetCON的实时性的一个有效措施。 ⑸ 设计开发了NetCON系统的简单网络管理软件，实现了NetCON系统的网络地址的管理、系统时钟同步、硬件故障检测与报警等管理功能，对基于SNMP管理的下一步开发也提供了一个整体实现框架。简单网络管理功能对提高NetCON系统的可实用性是很重要的。

With the expanding of control scales and the increasing wide use of Ethernet technology in industry fields, the networked control systems based on Ethernet have become hot subjects for development and study of control theory. This dissertation focuses on improving the real-time performance and practicability of NCS, and utilizing the improved method in NetCON system. Main work and contributions in this dissertation are described as following. Firstly, the design and implementation of the NetCON system is introduced and the key points of the design are explained. Combing with the characteristics of Ethernet, the problems of the NetCON system in real-time applications are analyzed. It is pointed out that the time delays in smart network nodes determine the real-time performance of the NetCON system. Secondly, the operating system is the very important point affecting the time delays in a smart network controller node, while the embedded Linux 2.6 is selected as a new embedded operating system to the smart network nodes of the NetCON system. This selection will heighten the real-time performance of the system for two reasons, one is the smaller scheduling cycle is adopted in Linux 2.6; the other is that Linux 2.6 supports the preemptive kernel scheduling but 2.4 not; this is the key difference. Based on the above, the relative work with upgrading the kernel of network controller from 2.4 to 2.6 is implemented correspondingly. Thirdly, many complex computations always present in control applications, such as in data sampling and in control algorithms. With a view to this fact, EP9302 microcontroller, which is one of ARM9 processors with a MaverickCrunchTM coprocessor, has been used as the hardware core of the smart network controllers in NetCON. For utilizing the accelerated floating point operations performed by the Crunch coprocessor in NetCON, the design of one cross-compile server is analyzed and implemented. Fourthly, several types of data can be synchronously transmitted in NCS, while some are real-time data but the others are not. Based on this fact, a general transmission scheduling method is presented in the paper, which is based on the Linux Qos. That is to say the method can allocate the network bandwidth and the transmission priority for data related with the transmitting request of the messages. In addition, for the real-time data in NCS general being high-speed and with short size, the NAPI is applied in the NetCON system to increase the network receiving speed. Finally, three types motor experiment based on NetCON, that is local control, control over Ethernet and control over wide wireless networks, are presented. Finally, the simple network management software of the NetCON system is designed and implemented, which incorporates the network address management, system clock synchronization and the remote monitoring of smart node hardware status, et al.