Synchronization Improvement of Distributed Clocks in EtherCAT Networks

Park, Sung-Mun; Kim, Hong-Ju; Kim, Hyoung-Woo; Cho, Chang Nho; Choi, Joon‐Young

doi:10.1109/lcomm.2017.2668400

Cited by 30 publications

(12 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The frequency of each slave's drift compensation is set by the Speed_Counter_Start register, and this determines the time period for the execution cycle of the drift compensation and is typically set as significantly higher than 10 ns [11], [16]. It is noted that the drift compensation of the reference slave is optional as a configuration condition of the EtherCAT DC synchronization mechanism, and the drift compensation of the reference slave must be turned on to ensure that the time synchronization works between the master and all the slaves.…”

Section: Drift Compensationmentioning

confidence: 99%

“…Subsequently, as soon as the system time function returns with each system time of the master and slave, the master stores the master system time in memory while the slaves send the slave system times to the master at each operation cycle, and the sent slave system times are stored in memory by the master. After completion of each experiment round, the system times of the master, reference slave, and last slave stored at each operation cycle are saved in an SD card, and the saved experimental results are transferred and analyzed on the analysis PC [11], [13].…”

Section: B Measurement Of Synchronization Errorsmentioning

confidence: 99%

“…The slave-slave time synchronization in EtherCAT networks is realized with a high degree of accuracy, as demonstrated by a slave-slave jitter of less than 12 ns in [10]. Additionally, an accuracy improvement method is proposed for slave-slave synchronization in EtherCAT networks, and the performance is demonstrated via experiments in [11].…”

Section: Introductionmentioning

confidence: 99%

“…Only EtherCAT slaves are equipped with special hardware for time synchronization that is typically not provided for the master [14], [15]. The time control loop (TCL) in the reference slave compensates for the master-slave synchronization error by only a fixed 1 ns correction of the reference slave clock every 10 ns without considering the error magnitude [11].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Accuracy Improvement of Master–Slave Synchronization in EtherCAT Networks

Park

Kim

et al. 2020

IEEE Access

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Drift Compensationmentioning

confidence: 99%

Section: B Measurement Of Synchronization Errorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Accuracy Improvement of Master–Slave Synchronization in EtherCAT Networks

Park

Kim

et al. 2020

IEEE Access

Self Cite

View full text Add to dashboard Cite

show abstract

“…Various researchers have tried to solve this problem using different control schemes [36][37][38]. However, these algorithms need to run in a separate real-time task, which could reduce the clock accuracy of the EtherCAT master because of context switching jitters.…”

Section: Synchronous Joint Space Controllermentioning

confidence: 99%

Network-Oriented Real-Time Embedded System Considering Synchronous Joint Space Motion for an Omnidirectional Mobile Robot

Delgado

Choi

2019

Electronics

View full text Add to dashboard Cite

This paper proposes a real-time embedded system for joint space control of omnidirectional mobile robots. Actuators driving an omnidirectional mobile robot are connected in a line topology which requires synchronization to move simultaneously in translation and rotation. We employ EtherCAT, a real-time Ethernet network, to control servo controllers for the mobile robot. The first part of this study focuses on the design of a low-cost embedded system utilizing an open-source EtherCAT master. Although satisfying real-time constraints is critical, a desired trajectory on the center of the mobile robot should be decomposed into the joint space to drive the servo controllers. For the center of the robot, a convolution-based path planner and a corresponding joint space control algorithm are presented considering its physical limits. To avoid obstacles that introduce geometric constraints on the curved path, a trajectory generation algorithm considering high curvature turning points is adapted for an omnidirectional mobile robot. Tracking a high curvature path increases mathematical complexity, which requires precise synchronization between the actuators of the mobile robot. An improvement of the distributed clock—the synchronization mechanism of EtherCAT for slaves—is presented and applied to the joint controllers of the mobile robot. The local time of the EtherCAT master is dynamically adjusted according to the drift of the reference slave, which minimizes the synchronization error between each joint. Experiments are conducted on our own developed four-wheeled omnidirectional mobile robot. The experiment results confirm that the proposed system is very effective in real-time control applications for precise motion control of the robot even for tracking high curvature paths.

show abstract

Innovation of EtherCAT adaptive synchronization control in embedded CNC

Cao

Wang

Jia

et al. 2023

Int J Communication

View full text Add to dashboard Cite

EtherCAT is a real-time Ethernet protocol and has been widely used in the field of motion control owing to its high speed (100 or 1000 Mbps), low processor occupancy, and good synchronization performance in slaves. However, the master-slave synchronization method is blank in the EtherCAT protocol. The study proposes a novel master-slave synchronization method that relies on the stable sync0 of reference slave by adjusting the trigger moment of master interpolation period to settle packet loss caused by EtherCAT master-slave un-synchronization, adaptively and dynamically. Furthermore, the proposed method improved EtherCAT to a whole new level, indicating that the EtherCAT master no longer depended on the real-time operating system (RTOS). In addition, a synchronization predictive compensation mechanism was adopted to eliminate the compensation lag defect of existing synchronization methods. Compared with conventional studies, the synchronization method improved compensation efficiency, settled inaccurate compensation with evaluation derived from different working frequencies, and eliminated accumulative error in clock. Finally, the proposed method added almost no computation and communication load and only required eight or 16 bytes to modify the EtherCAT frame coding in the interpolation period. Experiments were carried out on machine tools to demonstrate the advantage of the proposed method in improving the synchronization performance, with an average communication jitter of only 32-71 ns.

show abstract

Synchronization Improvement of Distributed Clocks in EtherCAT Networks

Cited by 30 publications

References 7 publications

Accuracy Improvement of Master–Slave Synchronization in EtherCAT Networks

Accuracy Improvement of Master–Slave Synchronization in EtherCAT Networks

Network-Oriented Real-Time Embedded System Considering Synchronous Joint Space Motion for an Omnidirectional Mobile Robot

Innovation of EtherCAT adaptive synchronization control in embedded CNC

Contact Info

Product

Resources

About