ChessBot - wooden chess-playing robot

Hello, this is one of my Arduino-projects - ChessBot, chess-playing robot. His brain is an Android-smartphone, that sees the chessboard, analyzes position and sends this info about move to the robot via bluetooth. This manipulator works with Arduino Leonardo and with 4 servos Tower Pro SG-90. You can ask some questions in comments, i’ll try to answer on some of them. I don’t want do tutorial about this project, because it’s very difficult to replicate it. Sorry for my english, it’s not my mother-tongue.