Bibinagar, Naveen Kumar (2010-08). Robustness of Ethernet-Based Real-Time Networked Control System with Multi-Level Client/Server Architecture. Master's Thesis. Thesis uri icon

abstract

  • The importance of real-time communication at the device level in a factory automation setup is a widely researched area. This research is an effort to experimentally verify if Ethernet can be used as a real-time communication standard in a factory automation setup, by observing the effects of packet delays, packet loss, and network congestion on the performance of a networked control system (NCS). The NCS experimental setup used in this research involves real-time feedback control of multiple plants like DC motors and a magnetic-levitation system connected to one or more controllers. A multi-client-multi-server architecture on a local area network (LAN) was developed using user datagram protocol (UDP) as the communication protocol. Key observations are as follows. (1) The multi-client-single-server system showed the highest packet delays compared to single-client-single-server architecture. (2) In the singleclient- single-server system, as the Ethernet link utilization increased beyond 82 percent, the average packet delays and steady-state error of the DC motor speed-control system increased by 2231 percent and 304 percent, respectively. (3) Even under high link utilization, adding an additional server to the NCS reduced average packet delays considerably. (4) With large packet sizes, higher packet rates were automatically throttled by Ethernet's flow control mechanism affecting the real-time communication negatively. (5) In the multiclient- multi-server architecture, average packet delays at higher packet rates, and at higher packet lengths were found to be 40 percent lesser than the those of the single-clientsingle- server system and 87.5 percent lesser than those of the multi-client-single-server system.
  • The importance of real-time communication at the device level in a factory

    automation setup is a widely researched area. This research is an effort to experimentally

    verify if Ethernet can be used as a real-time communication standard in a factory

    automation setup, by observing the effects of packet delays, packet loss, and network

    congestion on the performance of a networked control system (NCS). The NCS

    experimental setup used in this research involves real-time feedback control of multiple

    plants like DC motors and a magnetic-levitation system connected to one or more

    controllers. A multi-client-multi-server architecture on a local area network (LAN) was

    developed using user datagram protocol (UDP) as the communication protocol. Key

    observations are as follows. (1) The multi-client-single-server system showed the highest

    packet delays compared to single-client-single-server architecture. (2) In the singleclient-

    single-server system, as the Ethernet link utilization increased beyond 82 percent, the

    average packet delays and steady-state error of the DC motor speed-control system

    increased by 2231 percent and 304 percent, respectively. (3) Even under high link utilization, adding

    an additional server to the NCS reduced average packet delays considerably. (4) With

    large packet sizes, higher packet rates were automatically throttled by Ethernet's flow

    control mechanism affecting the real-time communication negatively. (5) In the multiclient-

    multi-server architecture, average packet delays at higher packet rates, and at

    higher packet lengths were found to be 40 percent lesser than the those of the single-clientsingle-

    server system and 87.5 percent lesser than those of the multi-client-single-server

    system.

publication date

  • August 2010