DES-Based Synchronization Algorithm Optimization for EtherCAT Master–Slave System

EtherCAT, known for its exceptional real-time performance and synchronization capabilities, is widely used in industrial multi-axis control systems. In these systems, the synchronization status of slave axes plays a critical role in determining the precision of the end-effector. While the distributed clock synchronization technology in EtherCAT achieves effective overall synchronization for the master–slave system, notable synchronization errors persist between non-reference slaves and the reference slave. To address this issue, this paper proposes an improved EtherCAT master–slave synchronization method based on the Double Exponential Smoothing (DES) algorithm. The proposed method begins by measuring the transmission delay between the master and the reference slave. Using this delay, the exponential moving average technique is applied to periodically adjust and compensate for synchronization errors between the master and the reference slave. Subsequently, the DES algorithm is employed to periodically calculate the clock drift of non-reference slave clocks relative to the reference clock, enabling corresponding compensation for the slave clocks. To validate the feasibility of the proposed method, an EtherCAT master–slave experimental platform was established using the Xenomai real-time operating system, and synchronization performance was evaluated. Experimental results show that the proposed method controls synchronization errors within ±90 ns in a six-slave experimental setup. Compared with synchronization error ranges achieved using only exponential moving average (EMA) for clock drift compensation, the proposed method reduces the synchronization error by approximately 16.36%, thereby validating its effectiveness.