It is always better to make bots in a set of modules which can be assembled together to form the required bot. For the dust bot there are two things required, first a gripper that can hold the balls and second a vehicle that can take that gripper from one place to another. First of all it is required to make a vehicle that can be controlled by the wired controls. After accomplishing this task we need a mechanism to grab the balls. Further the grip of the grabber should be of such strength that the balls don’t fall of the bot till we reach the finishing end. The movement of the gripper should be bidirectional and quite precise as we require the movement of the gripper in both the directions. The stability is the success of every bot. More the stability in your design better is your bot. Hence, the arm holding the gripper should be properly fixed and shouldn’t be unstable. Therefore, aluminum rods were chosen with clamps for enhanced stability of the gripper.  And most important the bot should utilize the off the shelf material and it must be really economic. 

DPDT stands for double pole double throw switch. By using this we can change the polarity of the applied voltage. It is used in situations where we need different outputs. It has 3 states ON, OFF, ON. The difference between the two ON is that the polarity of both the states is opposite with respect to each other.That’s the reason why it can drive the dc motor in both directions. It can also switch an ac motor but it can’t change the direction of the motor. Since, ac motor will run in same direction irrespective of the polarity therefore, it can only be used for switching ON and OFF for an ac motor but not for changing its direction.