From: brucec@phoebus.labs.tek.com (Bruce Cohen)
Subject: Re: INDUSTRY: NASA develops "telepresence" for exploration (Forwarded)
Date: 7 Feb 92 16:57:25 GMT
Organization: Software Technology Research Laboratory, Tektronix Inc.



In article <1992Feb5.195830.22487@watserv1.waterloo.edu> dstamp@watserv1.
waterloo.edu (Dave Stampe-Psy+Eng) writes:

> Didn't mention how they're planning to get around the 40-minute minimum 
> round-trip speed-of-light delay between Earth and Mars...  Even the 1.5
> second delay between the Earth and Moon will cause problems in a lot
> of applications.

First, just to satisfy my own obsessive need to pick nits, I have to
point out that the MINIMUM round-trip time lag, earth-to-mars and back
is about 7 minutes at closest approach (about 65 million kilometers
separation) and MAXIMUM is about 40 minutes (call it 400 million
kilometers).

As far as I know, no one has seriously suggested VR-style operation over
distances farther than the moon; I think the press release referred to
explorers *on Mars* operating the robots: 'Astronauts may someday explore
Mars without leaving their base camp using "telepresence,"'

There were several studies done by NASA sometime in the '80s examining
how to do exploration and construction tasks via teleoperation at Lunar
distances and exploration on Mars.  As I recall, the consensus was that
the only way was to assume most low-level, time-critical tasks (control
of motion, reaction to unexpected dangers like finding you're at the
edge of a cliff, etc.) and repetitive tasks like turning a bolt down
with a wrench, would be done by on-board AI control systems. The AI
would deal with what it could, and inform the remote operator when
something unexpected happened or when the current task was done.

I don't believe these studies looked closely at exactly how the operator
would interact with the robot, and I do see some real problems with
tightly-coupled VR-style teleoperation at Martian distances.  The moon
is not so bad, though you do have to give up some of the high-speed,
hand-eye coordination sorts of action that humans are so good at, since
the combined system will tend to hunt, if not oscillate with that kind
of delay in it.  There's a graphic description of how such a system can
go wrong in a disastrous way in Arthur Clarke's short story "A Meeting
with Medusa", in which a remote-controlled news camera platform has its
control connection re-routed through a satellite link without the
operator knowing it.  The unexpected additional 0.5 seconds of
round-trip delay causes the operator to lose it completely, destroying
the airship being photographed.  I think the idea of the studies was to
have the operator more supervise than control the robot directly, so
this wasn't an issue with them.
--
"The end cause ... is too often handed off as an afterthought to harried
interface designers who follow programmers around with virtual brooms
and pails." - Brenda Laurel in "Computers as Theatre"
------------------------------------------------------------------------
Speaker-to-managers, aka
Bruce Cohen, Software Technology Research Lab   email: brucec@strl.labs.tek.com
Tektronix Laboratories, Tektronix, Inc.         phone: (503)627-5241
M/S 50-662, P.O. Box 500, Beaverton, OR  97077