On Clock Synchronization Based On IEEE1588

Time synchronization problem originates from the requirement of developing distributed system and real-time tasks.The core problem is to achieve the time consistency among all the subsystems through time-synchronization method.The traditional GPS method and NTP protocol are not able to meet current industrial demand due to their high-cost and unpredictable message latency.Currently,IEEE1588 protocol is the best choice for time-synchronization problem,However,it often cannot achieve the precision level of sub-microsecond or nanosecond and it's not able to guarantee the stability of slave clock in the industrial reality.From the perspective of mathematical statistics,the objective of this paper is to promote a systematically statistical method to improve the time-synchronization precision and stability.The contributions are shown in the following.(1)Through the mathematical analysis for transmitting message latency,I decomposed latency into inherent jitter,temporary latency mutation and persistent latency change.In order to improve accuracy,dynamic threshold method and fixed-window real-time detection method are promoted.(2)In clock servo system,multi-model PID controller strategy is promoted for improving the slave-clock stability when step-mutation occurs.So slave clock system will become more smooth due to the less jitter.(3)By filtering PTP messages based on the detection of link blocking,qualified PTP messages will be choosed for calcuation of master-to-slave frequency offset.(4)Based on stateflow time-synchronization simulation system,all the promoted methods above get validated and verified.The simulation results show us those methods above can improve the adaptive ability of time-synchronization system for multiple types of latency changes,and the synchronization precision and stability of whole system as well.