Time Synchronization Based on Random Variables Analyzed in Real-Time Ethernet-Based Networked CNC Systems

Having analyzed the main random variables which affected the synchronization accuracy, this paper presents a time synchronization method with high precision of the networked CNC system based on RTE which combines the IEEE 1588 protocol with a ring topology. This synchronization method adopts the instant fixed-time forwarding mechanism increasing the synchronization frequency and high frequency measurement clock to decrease the measurement error, and uses the DPLL and the PI controller for drift compensation and offset compensation respectively to reduce the frequency drift of crystal oscillator. Meanwhile the algorithm of the DPLL and the PI controller are analyzed respectively. Finally, in this paper an experimental platform is built, and some experiments are conducted to verify the performance of the time synchronization method. The experimental results demonstrate that the synchronization method achieves high synchronization accuracy.