Newsgroups: comp.robotics
Path: brunix!cat.cis.Brown.EDU!agate!ames!kronos.arc.nasa.gov!doctor
From: doctor@kronos.arc.nasa.gov (Terry Fong)
Subject: Dante II - Mt. Spurr Expedition Status (3-Aug-94)
Message-ID: <1994Aug4.170744.29000@ptolemy-ethernet.arc.nasa.gov>
Summary: status information on CMU/NASA volcano robot explorer
Keywords: Dante, teleoperations, volcano, Alaska
Sender: usenet@ptolemy-ethernet.arc.nasa.gov (usenet@ptolemy.arc.nasa.gov)
Nntp-Posting-Host: tardis.arc.nasa.gov
Organization: NASA Ames Intelligent Mechanisms Group
Date: Thu, 4 Aug 1994 17:07:44 GMT
Lines: 125

The following is a status update on the Dante II project. Dante II is
an eight-legged robot (developed by the CMU Robotics Institute with
sponsorship from NASA) which is currently descending into the active
crater of Mt. Spurr, an Alaskan volcano 80 miles west of Anchorage,
Alaska. The primary objective of the Dante II project is to develop and
evaluate new techniques and technologies which can be applied to space
and planetary exploration. 

Throughout the Mt. Spurr expedition, Dante II is being remotely
operated from a base station in Anchorage using control station
software developed at CMU and NASA Ames. Live video coverage is
periodically available via NASA Select. Full mission details including
current status, real-time images/video, and technical data is available
via a WorldWideWeb server provided by the NASA Ames Intelligent
Mechanisms Group. This site can be accessed on the Internet using
information browsers such as NCSA Mosaic and the URL:

	http://maas-neotek.arc.nasa.gov/dante

Questions regarding the Dante II project may be addressed to me via email 
(terry@ptolemy.arc.nasa.gov). Reponse time may be slow.

Terry Fong
NASA Ames Research Center

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Status Report (3-Aug-94)

After remaining on the floor of the crater of Mt. Spurr for the second
night, Dante began the ascent up and out of the crater at 9:00 am ADT.
During the first few hours of operations, the robot moved about 15
meters up the slope at the bottom of the crater.  The slow progress of
the robot through the terrain at the bottom of the crater was not a
surprise - this area included the toughest terrain obstacles encountered
by Dante during the time in the crater, and commanding the robot to pick
it's way through the two-meter tall boulders and obstacles was a very
time consuming process.

As the robot emerged from the hardest area of the terrain to be covered
during the ascent, communication between the robot and the control
center was abruptly interrupted at 12:55pm ADT.  All communications with
the robot were terminated - no video images, computer commands or
scanner data were received from Dante, and it appeared that electrical
connectivity to the robot had also been severed.  The rim station and
rim camera located at the top of the ascent path were both functioning
and transmitting information back to the control center.  This lead to
initial speculation that either the robot or the support tether may have
experienced a rock fall strike which severely damaged the machine or
severed the communications or power conductors encased within the
tether.

The operators in Anchorage used the rim camera to scan the visible
length of the tether and the up slope portion of the robot.  This
inspection was hampered by poor visibility due to the density of the
crater plume and the cloud cover which filled the crater.  As the survey
was conducted, no noticeable indications of rock impact were found on
either the tether or the robot.  30 minutes after the initial loss of
communications with the robot, contact with the rim station and rim
camera was also lost.  However, contact between the control center and
the satellite dish was not interrupted.

The 30 minutes in which the rim station continued to function after loss
of contact with the robot is also the amount of time the rim station UPS
would last in the event of a generator failure.  Using the observable
effects of the communications loss with the robot and the base station,
and the fact that there continues to be contact with the satellite dish,
the control center team conferred to begin diagnosing the problem.

After careful consideration of the problem and an informal failure
propagation analysis, the team identified a scenario which would
generate the observed symptoms.  It is believed that the diesel
generator and power distribution system, which maintains the power
continuity between the robot and the power station on the crater rim,
may have shaken a connector loose.  During the last five full days of
operation with Dante, the power generator has been running continuously.
The generator can create significant vibrations as it runs, and these
vibrations may have loosened one of the plug and clamp connectors on one
of the conductors which pass from the power station to the robot and to
the rim station.  At this point, it is not believed that there is any
problem on board the robot, and the the cause for the signal loss is
limited to the power subsystem at the rim of the crater.

A team will fly out to the rim of the volcano tomorrow morning to
examine the rim station and power system (this activity could not be
conducted today due to inclement weather conditions on the volcano which
made flight opportunities unlikely).  If the suspected cause indeed
turns out to the reason for the signal loss with the robot, the problem
will be corrected and the system restored in fairly short order.  If it
is determined that the suspected cause is not the reason for the
interruption in communications, then the team is prepared to conduct a
thorough on-site inspection of the power subsystem, the rim station and
the communications subsystem as well a remote visual inspection of the
robot 600 feet below the rim station to identify the problem.

If the problem can be identified and corrected at the rim station, then
the rim party will fix it, restart the power flow to the robot, and
Dante will continue the ascent up and out of the crater.  The team is
prepared to reach the rim of the crater as early as 7:30am ADT tomorrow
(weather permitting), and the control center team is ready to resume
walking operations as soon as the power problem is corrected.

If the problem is identified as an issue with either the rim station or
the power station which cannot be corrected, or a problem with the robot
itself (which is not suspected at this time, but is always a
consideration), then the project would be concluded and a contingency
salvage plan will be put in place.  This would involve disassembling the
power and rim stations for transport off the mountain via helicopter,
and preparing to remotely extract the robot from the crater floor.  Due
to safety considerations associated with the high risk of injury by rock
fall, no team members will enter the crater to effect repairs.

It should be noted that even if the mission should be concluded at this
point and the robot be remotely lifted from the crater via either the
tether or the sensor arch, the primary objectives for the project have
already been successfully concluded, and the power and data loss would
not adversely impact the technical and scientific data gathered during
the traverse of the crater floor.

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-- 
_______________________________________________________________________________
 "Every once in a while declare        Terry Fong <terry@ptolemy.arc.nasa.gov>
  peace. It confuses the hell out      NASA Ames, M/S 269-3, Moffett Field, CA
  of your enemies" -- Rule of Acq. #76      (415) 604-6063, (415) 604-6081 lab
