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[214] Citation: Abstract
Networked haptic virtual environments (NHVEs)
are those in which multiple users collaborate and experience
force feedback at the same time. The robustness of such systems
needs to be tested under various network conditions that closely
mirror the Internet. Previously, we had proposed three virtual
coupling schemes to maintain position coherency in a NHVE,
which were tested using constant and then time-varying delays
using the actual Internet through UDP packet reflectors. In this
paper we present the results of comparing performance of the
virtual coupling schemes for a time varying delay emulated
using the popular network emulator NIST Net, with delay
conditions that existed during our real Internet experiment to
Italy. UDP was used for haptic data communication because of
the high transmission rate requirements for NHVEs. Experiments
were conducted for three fixed packet transmission rates of
1000, 500 and 100 Hz, and their performance compared using
an independent-samples t-test to the data obtained using the
Internet. Locally, the haptic update rate was maintained at
1000 Hz during the experiments. Our results show that the
NIST Net was a suitable emulator for testing with lower packet
transmission rates. At the transmission rate of 1000 Hz the
performance of the virtual coupling schemes were significantly
different from that of the actual Internet experiment.
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Updated: Tue Aug 19 09:16:10 2008
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