From: tolman%asylum@hellgate.utah.edu (Kenneth Tolman)
Subject: SCI: Latency in interplanetary transmission of telepresence
Date: Wed, 5 Feb 92 14:50:26 -0700
Organization: University of Utah CS Dept



  Yep, there is a huge transmission latency between Mars and Earth (an ever
changing one as well).  Note that the article for NASA suggested that the
teleoperator was located on Mars itself at base, not sitting here on Earth.

  However, it seems entirely possible to work even with such a huge latency.
(And with small latencies too to prevent amplifying overcompensating feedback)
What is needed is an accurate world model within the computer which serves
to generate the environment.  This requires that the model matches nearly
with the actual reality!  Thus the user could pick up a part of the space
station and reattach it, and the commands for this motion would be sent
out and later on the actual action is performed.  So the user operates in
a "pre-world", always hoping that what they see themselves doing actually
happens later.  When the model starts to deviate too significantly from
the reality (not noticed until the signal has gone out and back) the model
must be adjusted.

  This has the severe limitation of only working when the reality is 
already known and can be predicted under interaction.  An exploring robot
that turned a corner and found a cliff (expecting flatness) would not update
the users model until it had already fallen off.  However this technique has
great potential and suggests research into modelling physical phenomena is
needed to create accurately responding virtual environments.

Tom Tolman