Distributed Clock Research Articles

Dual-motor synchronous control technology based on EtherCAT

In order to solve the problem of position synchronization of two-motor coordinated control, this paper proposed a dual-motor position synchronization control system based on the industrial Real-time Ethernet——EtherCAT Technology. In this paper, the overall design scheme was put forward, and the synchronization mechanisms and algorithms of DC (distributed clock) were mainly analyzed. Experiments were carried out on the double-drive box transfer mechanism of the experimental platform, and the experimental results showed that the positions of the two motors was well synchronized, meeting the design requirements.

P.1.g.059 - Acute dose-response effects of LSD in healthy humans

EtherCAT has been widely applied in the motion control domain due to its advantages of the fast response speed, low CPU usage and good synchronization performance. Although the built-in distributed clock (DC) synchronization mechanism exhibits strong performance between slaves, the method of clock synchronization between the master and the reference clock is left open for selection by users and there are very few studies in this area. This paper introduces three synchronization modes for EtherCAT and analyzes the reasons for packet loss in free run mode and DC mode. This paper presents a novel method to realize the master clock synchronization with the reference clock. The proposed method can eliminate the settling time which is unusual in other synchronization mechanisms. The method is implemented on Windows with real-time extension and experimental results prove its feasibility.

A clock synchronization method for EtherCAT master

EtherCAT has been widely applied in the motion control domain due to its advantages of the fast response speed, low CPU usage and good synchronization performance. Although the built-in distributed clock (DC) synchronization mechanism exhibits strong performance between slaves, the method of clock synchronization between the master and the reference clock is left open for selection by users and there are very few studies in this area. This paper introduces three synchronization modes for EtherCAT and analyzes the reasons for packet loss in free run mode and DC mode. This paper presents a novel method to realize the master clock synchronization with the reference clock. The proposed method can eliminate the settling time which is unusual in other synchronization mechanisms. The method is implemented on Windows with real-time extension and experimental results prove its feasibility.

Synchronize Your Watches: Part II: Special-Purpose Solutions for Distributed Real-Time Control

The ability to carry out coordered activities in distributed applications is currently considered a basic requirement in most industrial scenarios as well as in many areas with demanding real-time constraints, such as modern electric power systems, the automotive/avionic domains, and some types of networked embedded control systems. For this reason, the majority of the networks that were conceived recently for use in these environments provide some means to deal with distributed clock (DC) synchronization. EtherCAT is a high-performance Ethernet-based industrial network. Its main goal is to enable the adoption of Ethernet communications in automation applications that require short cycle times and low communication jitters. This protocol is an open standard based on master-slave architecture. An important feature of EtherCAT is the DC synchronization mechanism, which enables all devices to share the same system time. In this way, typical control operations, such as the generation of coordered output signals or the precise timestamping of input events, can be synchronized for all devices in the network.

Evaluation of EtherCAT Distributed Clock Performance

EtherCAT is a real-time Ethernet protocol conceived explicitly for industrial applications. It is characterized by high communication efficiency, which permits control loops to be closed with short cycle times, and is provided with a suitable mechanism, known as distributed clock (DC), that enables synchronized operations to take place across the controlled system. These features can be profitably adopted, for instance, to support motion control applications. In this paper, the performance of the DC mechanism is evaluated by means of a thorough campaign of experimental measurements carried out on a real network setup. A number of factors have been taken into account that can affect accuracy and precision, and their effects studied in depth.