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Thursday, March 19, 2009

Chess Playing Robots at the AAAI-10

Many people are probably aware of the world-famous chess match between Garry Kasparov, a world champion, and Deep Blue, a super computer built by IBM, that took place in 1997. Deep blue won the match, but only with the help of humans because it couldn't really move the chess pieces without an arm. That is no longer the case, especially at the Small Scale Manipulation Competition held at the 24th AAAI (Association for the Advancement of Artificial Intelligence) conference at Atlanta in July 2010, where four robots from different universities paired up against each other and moved all the chess pieces themselves. "Small Scale" here means robots that are smaller than the size of a human, and the goal was not to beat the opponent in a game of chess, but to manipulate chess pieces adeptly and accurately. Extra points can be earned by showing the ability to recognize the pieces on the fly. The competition was one of the many great treats at the conference. As a conference attendee, I was fortunate enough to observe the real duels with my own eyes.

Gambit -- University of Washington Intel Lab
"Gambit" is a robotic arm built by the University of Washington Intel Lab using funding from Intel, and interestingly, one of the two main builders of the robot is actually an old acquaintance I had met at the HRI conference earlier this year in Japan. Her name is Cynthia, and with this connection, I was able to dig out quite some information about how the robot works. Gambit is equipped with both a depth camera and a regular video camera. It uses SIFT features for recognizing pieces on the board and also uses dead reckoning to remember the positions of them. The robot is even smart enough to line up the opponent's pieces it had captured neatly by the side of the board. The gripper has tactile sensors built-in, but according to Cynthia, they aren't very useful, and she had to spend a good amount of time picking the right kind of material for the gripper so it can grab onto a chess piece firmly. One special trick the robot has is the ability to call for help whenever it gets stuck or couldn't reach certain positions. The cost of the robotic arm is relatively cheap (a few thousand dollars) and the university is actually promoting it as a research platform to other researchers.

Chiara -- Carnegie Mellon University Tekkostsu Lab
The strange scorpion look alike robot on the right is "Chiara", a robot built by the Carnegie Mellon University Tekkostsu Lab. It is also an open-source hardware/software platform promoted by the lab priced around several thousand dollars. Before making a move, Chiara would first walk to align itself at the right location, then raise itself high and use its gripper-stinger to pick up the right chess piece. The mobility of the robot seemed really cool, and I thought it was needed because otherwise the robot wouldn't be able to reach pieces at the other half of the board. Turned out, the mobility was only there because it was part of the platform. The robot is actually only able to play half of the board. But because the competition only focused on the first ten moves of each robot, they were able to get away with the limitation. This robot is a vision-only robot, meaning it doesn't use ranger sensors such as infrared, sonar, or laser. Due to the special pattern of the chess board, recognizing the board is not a very difficult task, and the robot performed relatively well during the competition.

Georgia Tech's robot is a massive, expensive looking arm. I would have guessed the price range of the robot to be somewhere around $100K. A Swissranger depth camera was held above the chess board (from a tripod by the side) separately from the robot in order to read the board and chess pieces positions. Ironically, in the first move of the game, the arm misbehaved and made a big swing to the side, almost knocking over the camera-holding tripod. That totally messed up the camera calibration, and the Georgia Tech team got heavily penalized by the judges because they had to reposition the camera and recalibrate everything in order for the robot to work correctly.

The robot built by University of Alabama is definitely the champion with respect to cost. The designer of the robot proudly told me that the entire robot cost less than $700. It uses an iRobot create robot platform as the mobile base. Then a hobby robotics arm kit is used for the arm (our lab has a robotic arm very similar to this that cost around $400). An android phone with a built-in video camera is held above the chess board in order to recognize the board and pieces. Then a Netbook running Ubuntu is used to control and process data from each of those three parts separately through a wireless network. This robot is also a mobile one. It moves around the table in order to align itself to the necessary positions. In the first game though, the members of the team got quite frustrated because it would take forever for the Netbook to download data, which was not the case during the testing in previous day. Turned out they were using the conference shared wi-fi network, which became quite congested at the time of the competition and slowed everything to a crawl. In the second day of the competition, they used their own wireless network, and the situation was improved dramatically.

Each robot played against all the other robots, and the total points were tallied to identify a winner. Eventually, Gambit from University of Washington won the championship with flying colors (or is it really flying arms). The video below was made by the winning team in celebration of their triumph. VERY INTERESTINGLY, part of me and my voice were captured in this video as well, proving that I was actually there!! So here's your challenge of the day: see if you can find me in the video! The video also showed a match between a kid (rumored to be a world-ranked player) and Gambit toward the end, but I don't know who actually won.

Gambit's journey to Championship

In each and every AAAI conference (at least for the last few years), there's always a robot competition and the competition is always great fun! I am so looking forward to next year's competition. Now I just have to write a good paper before the submission deadline and hope it gets accepted....

Picture of the Day:

Beautiful night landscape of Atlanta (taken from the 56th floor of the Peachtree Plaza Hotel in downtown)