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.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-08-8368 |
| Date | 2010 August 1900 |
| Creators | Bibinagar, Naveen Kumar |
| Contributors | Kim, Won-jong |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | application/pdf |
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