The robot circling near the waypoint when the turning effort is saturated due to the resistance of deep snow.
Today was the best day in many ways. First of all, I was lucky enough to get back to the Summit after all the complication for past 4 days (flight cancellation, bad weather, and administrative approvals...).
We ran two long range autonomous mode tests, which were both successful. The first run was about 2.5km run. Yeti performed almost perfectly until 14th waypoint out of 20th waypoint. Then, the snow got too soft, and Yeti was not able to turn efficiently. As a result, when we got closer to Yeti, Yeti was making a circle around 14th waypoint without being able to go through this waypoint due to saturation of turning effort. We had to pull the robot out of deep snow in order for the robot to continue this long autonomous run. It took about 1 hours and 20 mins to get to 16th waypoint due to circling problem, and by this time, the voltage of the battery was too low for Yeti to move on. However, we definitely got a confirmation of how Yeti can travel for about 2km by itself. Also, the first test showed us that we need to prevent Yeti to go too deep into the snow.
The second long range test was little bit shorter because we wanted the robot to have enough battery power left to come home by itself. It was about 1km run. Even after deflating tire, we still ran into the problem of the saturation of turning effort in deep snow. We decided take of UNH package which was weighing down the robot too much. After this, the robot had much easier time traveling through deep snow and accurately hitting each waypoint. In 50 mins, the robot completed the 1km run, and successfully came back home autonomously.
The two tests show that we either have to increase the robot's capacity to turn or to decrease the accuracy of waypoint following. These will prevent the robot from circling around the waypoint without going through it. Also, we know that the weight of the instrument package can be a great obstacle in a deep snow reducing the robot's ability to turn.
Also, we carried out quick test for each stopping mode using the instrument laptop, using a short 5 point autonomous run. The results were very successful. All 3 stopping modes were carried out perfectly, suggesting that the robot will be able to perform stops configured to the need of various instruments.
Although we did not have time to travel all the way to the other side of the skiway to do an accurate plume experiment, we were very satisfied by the robots ability to carry out a long range autonomous travel as well as stopping patterns.