The robot is designed in such a way that the small obstacles dropped by other robots could be handled or diverted automatically. The design has been taken from the 60s train models in which a special mechanical devices is mounted on the train engines known as cowcatcher to divert the animals that come in front of the trains.
Similarly, our model of robot has a strong piece of shafts mounted in front of the robot to protect it from the obstacles.
Note: We have not used Magnetic sensors as there may be chances that the magnetic readings could get altered by the other devices in vicinity.
The position of the sonar and color sensor are such that it will not be altered by most of the lego objects.