The QR codes probably encode behavioral scripts to apply to an object that the robot encounters.  So a box with one QR code may mean that the robot should attempt to pick it up even after interruption.  A different QR code may mean that the robot should give up if it is interrupted when picking up the box.  A different QR code may mean pick up box and move it to self.  A QR code next to a door may mean that the robot should exit it automatically when it gets within a certain distance of it.