The idea was to make an extremely simple Bluetooth-controlled robot. It was done with an effort to understand the working of the Bluetooth module (HC-05) and how to use it. It can move forward, backward, left, right and stop by giving letter inputs of 'f', 'b', 'l', 'r' and 's' respectively.
Note: This model uses Adafruit L293D motor shield. This requires you to download and use a particular library for the same. You can use a generic motor shield as well but the code will change. For those of you who want to use the Adafruit one, please refer the following link:
(All the credit goes to the creator of the video, I learnt how to use the motor shield from the above mentioned link and hence I am merely recommending the same)
The other prerequisite needed is how to use the bluetooth module which can be learnt easily online.