BB-8 is a fictional droid character in the Star Wars franchise. It has a ball-shaped body and a domed head. BB-8's body rolls independently from the head, which always stays near the vertical axis of the droid.

BB - 8 Droid

At RoboCET, we built a BB-8 robot using the Arduino Uno. Our BB-8 is controlled by Bluetooth controller application (like Arduino Bluetooth Controller-All in One App) which can be installed on your phone. Pair the Bluetooth module to your smartphone.

Materials Used:


1. Bluetooth module Interface Arduino

HC-05 Bluetooth Module is a Bluetooth system used to wirelessly connect microcontrollers with Bluetooth-enabled devices like smartphones. Its circuit is simple so that the user only needs a few steps to connect the Bluetooth module.

Bluetooth module Interface Arduino

2. Motor Driver interface with Arduino

Motor drivers serve as an interface between the motors and the control circuits. It allows you to control the working speed and the direction of two motors simultaneously. Motor Driver has 4 input pins, 4 output pins, 2 enable pins, Vcc, Vss, and GND.

Motor Driver interface with Arduino


1. Physics Behind the Body

BB-8’s body is a sphere that can roll. How do you make a sphere roll without pushing it? It requires a mass that can move inside the sphere. We enclosed a small wheeled vehicle inside the sphere.

As the car moves up the wall of the sphere a little, the center of mass of the entire sphere shifts upwards from the vertical axis with respect to the point of contact. When the center of mass shifts upwards, an external torque acts on the sphere. This torque then boosts the angular momentum of the sphere and causes it to roll. As the sphere begins to roll, the centre of mass tends to remain at its lowest point.

1. Physics Behind the Head

The head of BB-8 is not affixed to his body. The head is held in place by magnetic attraction to the body. In order to keep the head upright, the weight of the head must be less than the force of attraction. We used neodymium magnets here.The magnet inside the body is erected using a pipe fixed to the Bluetooth car.To minimise the friction between the body and the head, the rollers from the roll-on deodrants are placed between them.

Working Videos:

BB - 8 Droid Without Head
BB - 8 Droid Trial Run


Project Done by: