Today we had a successful day of remote driving via satellite, but not from the United States; today Nomad was driven for 698 meters from Santiago, the capital of Chile. It may seem like a short distance, but in fact it is more than three times the nominal distance expected of the Sojourner robot. Francisco Lira, the person who brought you live panospheric imagery on the web, was in the driver's seat during this early afternoon test from Pontificia Universidad Catolica de Chile, using a satellite link supplied by Entel and network hardware by Coasin. We welcome the addition of this new remote driving station, look forward to having them drive again in the future, and especially welcome their enthusiasm: Francisco offered to drive Nomad all the way to Santiago (1000 kilometers away).
Today was not a very successful mechanical day, however. First of all, two of our rental trucks were out of commission and being repaired. But more importantly, during some tests of a new driving configuration called a Point Turn, the bearing on Nomad's left front wheel seized. A Point Turn describes what occurs when a vehicle rotates in place without moving forward or backward. Other vehicles (like tanks and some other robots) can perform point turns by simply driving their wheels in opposite directions; spin the left wheels forward and right wheels back, and you will turn clockwise. However Nomad has a special configuration in which all four wheels are physically rotated into the direction of travel; if the wheels formed a square, then adjacent wheels would be turned 90 degrees away from each other. It was during the first set of software tests of this configuration that the bearing, whose seal had broken earlier, froze and caused us to shut down for the day. Many rocks had gotten wedged into the wheel during the month of travel on this rugged terrain, breaking the seal and allowing dirt and particles to accumulate. The bearing finally gave way during this test. Still, prior to this problem in the afternoon, Nomad had been driven 4.279 kilometers from the Carnegie Science Center this morning.
Finally, today was the last day for team member Carlos Guestrin. Carlos was with us for a week, testing and demonstrating the Skyline Position Estimation technology. We are sorry to see him go, partly because he's a good guy, partly because his tests went so well we'd like to see them continue, but mainly because his rental truck still has working shock absorbers and a tape deck. Yes, we will really miss Carlos....