lego mindstorm nxt radar robot (video)

this lego robot can move without hitting any obstacle.it is programed by the lego mindstorm nxt programing tool. Firstly it finds zero position of the ultrasonic sensor by the help of color sensor.White stick means the front side and red stick means the backside.
Then it moves forward until there is an obstacle closer than 30 cm. Then it stops and ultrasonic sensor turns one side and then turns the other side.Meanwhile program determines the longest distance around.After that, robot turns to the longest place by calculated angle. robot is also enhanced with the touch sensor mounted in the front for the obstacle that the ultrasonic sensor cant detect. When touch sensor is pushed, firstly robot goes backward during 2 seconds to go away from the obstacle.Then it looks for the longest distance again.