Implementation And Application Of Linux-based POWERLINK Communication Technology

The communication of traditional motion control system mainly depends on the field bus technology, its real-time performance, reliability, stability and openness would be difficult to meet the demands of modern manufacturing. Real-time industrial ethernet has been applied in industrial control field, which effectively improves the real-time performance and stability of motion control systems. Based on a thorough comparative analysis of various real-time ethernet, this dissertation selects a real-time industrial ethernet-Ethernet POWERLINK whose openness is the best as the research object. Employing the Linux system as the implementation platform, realization and application of POWERLINK communication technologies are carried out. The main research work is summarized as follows.1. In this dissertation, the system structure of real-time kernel RTAI is studied in depth. To realize real-time operating system of RTAI/Linux hardware, the real-time kernel RTAI is ported to Linux and used to manage all the hardware interrupt, extending the hardware of Linux system. The hardware performance of RTAI/Linux system is verified, which provides a feasible operation platform for the realization of the POWERLINK protocol.2. According to the protocol architectures and hardware platforms of POWERLINK, we developed an overall solution for transplant. In this dissertation, we analyzed the source code of openPOWERLINK. We also systematically introduce the principle and protocols constitution of POWERLINK as well as the work flows of network management state machine. Combined with Linux kernel network architecture, we selected a kernel porting manner to achieve POWERLINK protocol in the Linux kernel.3. In this dissertation, we built a POWERLINK master station in the Linux system. Combined with hardware platform and the underlying module code of openPOWERLINK, we modified the clock driver module code, designed interrupt service routine as well as ring shared cache. Lastly, we bound the openPOWERLINK protocol with Socket which is Linux network interface.4. The POWERLINK master station, which is implemented in the Linux system, is used in the servo control system to monitor its communication jitter, synchronization and stability. We used WireShark which is a network protocol analyzer to track and verify the startup process of POWERLINK in detail, and verified the other properties of POWERLINK. Firstly, we applied POWERLINK master to two-dimensional servo motion platform, to achieve circular interpolation. Secondly, we detected communication jitter of POWERLINK protocol. Thirdly, we did an experiment that keeping the POWERLINK master station communicating with multiple POWERLINK slave stations for a long time to monitore the stability and synchronization of the network communication. The experimental results show that the POWERLINK protocol based on Linux has good synchronization and stability.