Thursday, July 21, 2011


After the many flight delays and cancellations yesterday, Suk Joon was finally able to fly in this morning. Immediately following lunch we got straight to work. Suk Joon tested the various stopping methods in the new instrument laptop code and was able to get all of them working.

Due to the favorable weather conditions, we decided to do a full test. We set a course of points 50-150m apart from the north end of camp and moving north east. During the test the snow ranged from very hard(<1 of boot sinkage) to soft (>6 in of boot sinkage). Yeti was able to complete the first 13 waypoints, but the thick snow at the 14 point cause Yeti to go in circles around the point, never getting close enough to register that it was at the point.

Yeti driving off into the wild on its autonomous journey

After dinner we attempted to do a nearly identical run. The cold weather helped firm up the snow and Yeti was able to reach the waypoints after circling them several times.

The flight out of Summit is still scheduled for the 23rd so we will start packing up after breakfast tomorrow. This trip has gone by way too quickly. I've just started to get use to the altitude and almost all of Yeti's mechanical problems have been solved. I'm definitely going to miss Quentin's wonderful cooking, but a nice warm room will be a welcome change after a week in a freezing cold tent.

Day 7 the best day

Yeti traveling autonomously doing square wave pattern

The robot circling near the waypoint when the turning effort is saturated due to the resistance of deep snow.

Tom trying to deflate tire in order to reduce slippage and ground pressure.

View of the Summit Camp from far away

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.

Wednesday, July 20, 2011

Bad Weather

A huge snow storm rolled in today. Summit has received several feet of snow and the powder is really soft. Walking outside of the camp I've been sinking down to my knees at points. I attempted to take Yeti out this morning and as soon as Yeti passed the berms on the north end of the camp, it sunk past its motor housings. With the continued snow and warm weather coming up, I will be unable to operate Yeti off base for several days.

Days 4-5

Day 4- Brandon and I took Yeti off base for the first time. We strapped Yeti to a sled and took a pair of snowmobiles west of the skiway. I entered the wrong coefficients for the autonomous control so Yeti struggled to make the turns fast enough. The snow was quite deep and Yeti's tires would dig down until the motor housings touched the snow, but Yeti never got stuck. Travel was quite slow because the tires were slipping.

Later in the day, I took Yeti out to the north of camp, but Yeti got stuck in the snow drifts on the north end of camp. I took manual GPS measurements of a safe path through the berms for future travel.

Day 5-Took Yeti out to the Northeast of the camp, parallel to the skiway. The IGERT students arrived today and several of them volunteered to help me. After fixing the control coefficients Yeti appeared to be running perfectly. About 500 meters away from the base, Yeti got stuck and managed to dig itself in. I inspected the spot where Yeti got stuck and could find nothing different at that point. Yeti was still slipping, especially when turning. To retrieve Yeti I towed a group of IGERT students behind a snowmobile. I followed behind Yeti as one of the other students drove Yeti manually using a laptop. We lost radio contact with Yeti briefly and nearly ran into the highly explosive JATO engines, the only obstacle on the north end of camp.

After returning, I measured the air pressure in the tires and found one tire at 30+psi and the others around 10psi. I took air out of the tires until they were all at about 4psi. This should prevent some of the slipping, but I haven't had a chance to test this.

Tuesday, July 19, 2011

Notes on Summit and the Project

Summit is a camp at the peak of the Greenland ice sheet. The camp is located at about 10,500 feet elevation and the temperature stays below freezing year around. The temperature has generally ranged between -20F and 20F. Various scientific groups do a variety of research on the snow, air, and ice in the area. Food is prepared by the camp chef who has cooked a variety of delicious meals from curry to gumbo.

This summer's deployment to Greenland has two main purposes. First, it is a test of the autonomous control system on Yeti to ensure it can follow complicated paths as required by scientists. Second, Yeti is collecting surface roughness data for Dartmouth researcher Mary Albert and particulate matter data for UNH researcher Jack Dibb.

The overall goal of the Cool Robot project is to create an autonomous robot platform which can be used with a variety of scientific packages. Yeti, along with the solar powered Cool Robot can be programmed with GPS coordinates and sampling procedures and allowed to collect data with little or no user interaction.

Days 3 and Pictures from Day 1 and 2

pictures taken on the flight from Kanger to Summit

Photos taken by Suk Joon of the area around the base at Kanger

The KISS building we lived in at Kanger

The C130 which transported us to Summit

unloading the transport

Our work space in the Science Operations Building

arriving at Summit

Tuna melts for lunch

Manually driving Yeti behind the base

The tents we sleep in. They stay relatively warm, but my water bottles are partially frozen when I wake up in the mornings.

Suk Joon had to leave due to Altitude sickness so I've recruited other students up at summit to help me.

7/17 - Ran a 250m long test using a square wave going north of the Science Operations Building. The sensor package was assembled on the sled with the Trimble GPS antenna going between the instrument laptop and UNH's C.R.A.P. Rigid poles were used over ropes to prevent the instrument package from flipping and to allow Yeti to backup. Ropes were used to attach the poles to the sled to allow for some give between the robot and the sled.

The control code worked perfectly and the robot turned with almost no oscillation. Although this test was conducted entirely in base, data was still collected with the two particulate filters and the GPS.

A group of high school students from Greenland, Denmark, and the USA came to Summit for several days. I gave a short demo of how Yeti works and convinced several of them help me take Yeti on several runs

Second Day at the Summit

Today, we decided to fix the problems that we found yesterday.
In the morning, we first worked on the connection between the sled and the robot. We first changed the connection from the pipe/ aluminum bracket to the pipe/ rope configuration. This hammock configuration enabled the sled to be offset from the robot so that the turning momentum of the robot was not so big. Furthermore, we shorten the pipe so that the distance between the robot and the instrument sled was not so big. After this change, the turning of the robot was significantly faster and smoother.
In the afternoon, I had to take a break due to altitude sickness. While I was taking a break, Tom worked on setting up of Trimble GPS. By the end of the afternoon, Tom configured GPS successfully.
In the evening, we did several autonomous runs with the instrument sled connected to the robot. Yeti completed the runs successfully even with more complex patterns of square wave. However, the robot again failed to stop after the completion of the autonomous run.
Late at night, I worked on the dynamic C code and the driving java code to fix this problem in the autonomous run. Unfortunately, I did not get a chance to test to code before I had to fly back to Kanger for altitude sickness.

First day at the Summit

After 2 hour flight in National Guard's Cargo Airplane, we finally arrived at the Summit. After a quick lunch, we went to straight to work.
After unpacking all the crates, we first decided to test out Yeti's autonomous run. Thankfully, the autonomous run was successful after tweaking the coefficients of the Proportional Integral Control in the driving logic.
Then, we decided to connect the instrument sled to Yeti to see whether Yeti is functional while towing the sled. When we connected the sled with the pipe that was used to connect GPR, we found that the turning momentum of the robot + sled was too great. When we manually controlled the robot to turn, the robot was barely turning even at the highest speed differential between the left and the right wheels. Therefore, we decided that we should shorten the distance between the sled and the robot as well as make the connection more flexible instead of using pipe and aluminum bracket.
Also, during the autonomous run, the robot sometimes restarted automatically the autonomous run after finishing the first run. This seems to be an error in the dynamic C driving code that needs to be fixed for tomorrow.
In the evening, we demonstrated the robot's autonomous run to NSF's media group and journalists from AP and popular mechanics. Then, we did interviews with them as well.