High-precision time synchronization in real-time Ethernet-based CNC systems

Xu, Xiong; Xiong, Zhenhua; Wu, Jianhua; Zhu, Xiangyang

doi:10.1007/s00170-012-4246-5

Cited by 18 publications

(9 citation statements)

References 24 publications

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“…between a machine tool, a handling robot and a connecting PLC. Motions must be synchronized, switch times coordinated and many more conditions met [37]. We often find configurations without an explicit master functionality, merely the state control of the whole production cell is distributed among the individual machines.…”

Section: Cyber-physical Production Systemsmentioning

confidence: 99%

Special Issue on Smart Production

2019

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Section: Cyber-physical Production Systemsmentioning

confidence: 99%

Special Issue on Smart Production

2019

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“…A clock servo is a control system that uses frequency compensation to periodically correct the time offset [25]. There are many studies on clock servo [26][27][28][29][30][31][32][33][34], but few provide a detailed evaluation of synchronization performance under QIDA.…”

Section: Introductionmentioning

confidence: 99%

A Fuzzy-PI Clock Servo with Window Filter for Compensating Queue-Induced Delay Asymmetry in IEEE 1588 Networks

Zhang,

Li,

Wang

et al. 2024

Sensors

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Clock synchronization is one of the popular research topics in Distributed Measurement and Control Systems (DMCSs). In most industrial fields, such as Smart Grid and Flight Test, the highest requirement for synchronization accuracy is 1 μs. IEEE 1588 Precision Time Protocol-2008 (PTPv2) can theoretically achieve sub-microsecond accuracy, but it relies on the assumption that the forward and backward delays of PTP packets are symmetrical. In practice, PTP packets will experience random queue delays in switches, making the above assumption challenging to satisfy and causing poor synchronization accuracy. Although using switches supporting the Transparent Clock (TC) can improve synchronization accuracy, these dedicated switches are generally expensive. This paper designs a PTP clock servo for compensating Queue-Induced Delay Asymmetry (QIDA), which can be implemented based on ordinary switches. Its main algorithm comprises a minimum window filter with drift compensation and a fuzzy proportional–integral (PI) controller. We construct a low-cost hardware platform (the cost of each node is within USD 10) to test the performance of the clock servo. In a 100 Mbps network with background (BG) traffic of less than 70 Mbps, the maximum absolute time error (max |TE|) does not exceed 0.35 μs, and the convergence time is about half a minute. The accuracy is improved hundreds of times compared with other existing clock servos.

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“…The associate editor coordinating the review of this manuscript and approving it for publication was Bohui Wang . clock, and other non-reference slaves' clocks are adjusted to the reference slave's clock. Although the DC mechanism enables synchronous operation of devices in distributed system applications, a recent demand has arisen for more precise synchronization performance via distributed real-time precision control applications such as multi-axis motion control systems including robots and computerized numerical control machines [7]- [9].…”

Section: Introductionmentioning

confidence: 99%

Accuracy Improvement of Master–Slave Synchronization in EtherCAT Networks

Park

Kim

et al. 2020

IEEE Access

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In the study, we develop a method to improve the accuracy of master-slave synchronization in EtherCAT networks. The method involves two key compensations that are not considered in the EtherCAT protocol. First, the propagation delay between the master and reference slave is measured, and the system time of the reference slave is then compensated for the measured propagation delay. Second, the bias component of the synchronization error between the master and reference slave is periodically estimated, and system time of each slave is then compensated for the estimated bias component. The entire method is implemented as part of the master application without modifying the EtherCAT protocol or requiring excessive computation load or large memory space. Thus, the developed method is advantageous because it can be immediately applied at low cost to existing EtherCAT networks. By performing extensive experiments based on a Linux-based EtherCAT master, we demonstrate that the developed method significantly improves the accuracy of the master-slave synchronization in EtherCAT networks.

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High-precision time synchronization in real-time Ethernet-based CNC systems

Cited by 18 publications

References 24 publications

Special Issue on Smart Production

Special Issue on Smart Production

A Fuzzy-PI Clock Servo with Window Filter for Compensating Queue-Induced Delay Asymmetry in IEEE 1588 Networks

Accuracy Improvement of Master–Slave Synchronization in EtherCAT Networks

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