The robots sequence from one behavior to another as they accomplish their task of gathering trash. Initially, a tiny color camera guides the robots to trash, which they grab with a specially-designed gripper. The robot's vision is sometimes fooled, so they may grab non-trash objects like table legs. Once a robot has a piece of trash in hand, it searches for a trash can, again using vision. After locating a trash can and moving to it, the robot drops the trash nearby.
Many people wonder why the robots are painted fluorescent green.
Although it does make them a bit more flashy, there's another reason. Bright green is easy for the robots to see, so they use it to keep tabs on one another. Unfortunately, they confused dark shadows under tables with trash cans. The result was that they sometimes hid trash under furniture instead of throwing it away. Maybe that's just a sign that robots are becoming more human all the time.