LORAX

The Life on Ice: Robotic Antarctic Explorer (LORAX) is researching and field testing the necessary technologies to enable an autonomous rover to conduct survey traverses of the Antarctic ice sheet. Assess autonomous navigation capability on snow/ice Specifically the rover will circumnavigate geologic features that protrude through the ice (nunataks) and sample and measure the abundance of microorganisms surviving in the top 10cm of ice to understand how microbes migrate in Antarctica.

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Field Report

February 24-25, 2005
Lake Mascoma, New Hampshire

Objective

The goal of this field experiment is to establish the mobility of the Nomad configuration and the technologies for autonomous navigation meet the requirements of the survey traverse intended in our Antarctic science investigation of micro-organisms living in surface ice.

Agenda

Execute continous 10km traverse
Measure wind turbine power performance

Status and Progress

Execute continuous 10km traverse. We were successful in our efforts to achieve 10 kilometers of uninterrupted autonomous traverse and demonstrate a milestone towards the technical feasibility of a 100km Antarctic traverse.

We began the day by recalibrating Nomad's stereo cameras in order to obtain settings that work well over the entire range of light conditions (bright mid-day to low-contrast late-day). Nomad's generator, which we plan to eliminate in favor of solar and wind power, needed treatment to remove water/ice that were interrupting uniform power output and causing computers and communications equipment to reboot. Our goal was to prepare everything to run continuously for an entire day.

We chose a route of eight latitude/longitude points that circumnavigated Lake Mascoma and commanded Nomad to execute the route twice, each circuit being about 7 km. The lake surface is 45 cm of solid ice with 15 cm of snow overlaid. There were no physical barriers to Nomad's mobility, just as we expect in Antarctica, but there are a fair number of ruts/tracks that Nomad's Navigator might choose to avoid.

After commanding the path to Nomad we had only sit back and watch for 8 hours. Nomad used its onboard compass and wheel odometry to dead reckon from goal to goal. Upon reaching each goal, the robot would stop simulating the time before and after initiation of science activities. The Navigator used stereo images to model the terrain in front of it to choose an obstacle free path. At dusk when light levels drop too low for vision, Nomad's laser continues to operate and cause the vehicle to backup and recover its path when an obstacle trips the "virtual bumper"--the loss of sufficient light occurred --after about 6.5 hours when Nomad had travelled 11 km.

After just under 8 hours (traveling 0.5m/s) Nomad returned to its starting point, for the second time, having traveled 14078m. It is important to note that the snowy terrain is mostly featureless so the robot was primarily looking for unexpected items in its path. It did this all day long with no need for assistance, demonstrating a first instance of day long autonomy in a snow/ice environment.

Upcoming

Archive representative sample of snowy terrain images
Assess mobility on snow-covered slopes
Pack Nomad and equipment

Weather

Cold, 10F (overnight -5F), still to light breeze (10-15kph), partly sunny


Field Report

February 21-23, 2005
Lake Mascoma, New Hampshire

Objective

The goal of this field experiment is to establish the mobility of the Nomad configuration and the technologies for autonomous navigation meet the requirements of the survey traverse intended in our Antarctic science investigation of micro-organisms living in surface ice.

Agenda

Deploy Nomad to frozen Lake Mascoma
Assess autonomous navigation capability on snow/ice
Integrate wind turbine and measure performance

Status and Progress

Deploy Nomad to frozen Lake Mascoma. Nomad and all equipment were successfully shipped our collaborators at the Cold Regions Research and Engineering Lab. We quickly unpacked and had the local towing company haul Nomad, via tilt-bed truck, to Lake Mascoma. Researchers from CRREL had made ice thickness measurements and confirmed 18" of ice, safe conditions for our rover trials. At the lake we finished assembly and began checkout tests on actuators and sensors. Nomad survived the trip in excellent condition.

Assess autonomous navigation capability on snow/ice. Although we had planned for ice, we arrived at Lake Mascoma after a night of heavy snow. Nomad however had no difficulty with 6 inches of snow onto of the ice.

Initially we experienced communication drops out and controller resets but traced those back to power problems. We found Nomad's internal generator was sagging to 80V and this we due to icing in the carborator. We built a left-handed smoke shifter to redirect the generator exhaust onto the carburator to keep it warm and it has been running smoothly at 120V since.

For the bright snow we've closed camera apertures and recalibrated the stereo vision system. There is enough texture on the snow and ice that Nomad is producing excellent terrain maps, although they are mostly flat. Nomad also carries a laser scanner to act as a "virtual bumper". We have verified improved the filtering on the laser so that it is not confused by falling snow. Other refinements to the navigation system have improved tracking of heading by more finely resolving steering arcs.

Integrate wind turbine. We have conducted a simulation study to solar and wind energy in Antarctica to determine whether our intended test area near Carapace Nunatak will be able to support a continuous solar/wind rover mission. We've installed a wind turbine on Nomad to assess stability and measure output. An anemometer gives us continuous wind speed which we can use to correlate turbine power to our model.

Upcoming

Measure wind turbine performance
Demonstrate continuous 10km traverse

Weather

Cold, 15-25F, still (morning) to light breeze (10-15kph), overcast (mornings) to partly sunny


For information contact:
Dr. Dimitrios Apostolopoulos or
Dr. David Wettergreen

This research is supported by NASA.