| Summary: | 碩士 === 國立臺灣大學 === 電機工程學研究所 === 96 === IEEE1588 standard is a precision time synchronization protocol (PTP). It is designed to synchronize real-time clocks in the nodes of a distributed system that communicate using a network. Within a subnet, the PTP system is expected to achieve the synchronization accuracy in sub-microsecond range. Thus, it is applicable to traditional measurement and control systems, industrial automation systems, communication systems, electrical power systems and many other areas of modern technology.The unit of clock servo plays important roles in the PTP system. It is usually implemented by proportional integral (PI) controller. The time offsets between the master and the slave clock are fed into the PI controller. The output of the PI controller is used to steer the slave clock to synchronize with the master clock. Therefore, the relative tick-rate of the slave clock can be stabilized. In order to improve the performance of the PI controller, this study adopts the gray theory to determine the parameter of the proportional term of the PI controller. The drift of the time offset from master clock can be obtained by using the gray prediction algorithm. Accordingly, the gray PI controller makes the system reduce the time to reach steady state. To assess the performance of the system, this study integrates the PTP software and the network interface with timestamper to establish a subnet. For the stability analysis of the system under tests, this paper utilizes the ITU-T recommended Allan deviation. Experimental results show that the performance of the gray PI controller is better than the traditional one. The transient response time of the system is significantly reduced by introducing the proposed gray PI controller.
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