How Does BB-8 From ‘Star Wars IV: The Force Awakens’ Work?

With trailers of the new Star Wars movie, The Force Awakens, being aired everywhere, one character that repeatedly steals the show is the new round astromech droid BB-8. For the uninitiated, an astromech is a droid that serves as an automated mechanic on starships, sometimes working to co-pilot the aircraft during missions from specialized sockets exposed to space. Now that you’re enlightened and your cool quotient has gone up considerably, let’s look at what’s so different about this droid and why people are going so wild over it.


The most amazing thing is that the droid is not a computer-generated animation, but an actual robot, conceptualized by the Star Wars team and executed by Sphero. Looking at the rolling droid, it seems like the head is detached and floating over a globular body. The moving dome-shaped head also gives a comical aspect to it. However, everyone is curious about the technology that makes this droid’s navigation possible. For example, how does the dome-shaped head always stay on the dorsal (top) side of the body when the body is rolling? Also, how does the body roll forward with a purpose and not tumble out of control?

Although there is no formal account of the technology used, geeky fans have tried to fish for information and connect the pieces of the puzzle to come up with a rudimentary explanation. The body of BB-8 actually works more or less the same as the Sphero toy; an automated spinning ball. Two possible mechanisms are suggested, namely, the body contains either a four-wheel drive system or a mast-like arm connected to a drive system that always maintains a relative position with respect to the sphere.


But how does it do that? Think of the body as a hollow ball that contains a mass with wheels inside it. When this mass moves up the walls of the sphere even a little, the centre of mass for the whole sphere shifts. This creates torque, due to the gravitational force acting on the mass, and makes the spherical object rotate around its axis. However, if the surface is not flat and smooth, then the torque interacts with the external friction, which causes angular momentum to develop and propels the body forward. In case of our BB-8, the drive system has a base plate that acts as the weight or mass inside the body. This contraption also consists of a motor connected to omni wheels, which make the sphere rotate in any direction. Additionally, the robot uses gyroscopes (direction and balance) and accelerometers (momentum) and can be controlled using a remote.

Now we turn to its head, which basically looks like a hyperactive squirrel when it rotates over its body. The drive system is thought to contain a mast, just like one in the Sphero. According to the Sphero patent, this arm can rotate and magnetically interact with the external environment. Therefore, the domed head might contains a high-powered magnet that is strongly attracted to the arm inside, which keeps it in place on the top while the ball rolls. The head may also have ball bearings that make its cruising action over the body swift and smooth.

You can even have your own miniature BB-8, which can be controlled by an app on your phone. Now you know what you should ask Santa for this Christmas! That list never seems to end!


  1. BB-8 – Wikipedia
  3. How BB8 Works
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About the Author:

Rujuta has a MA in Counseling Psychology and MSc in Cognitive Science. She is currently pursuing a PhD in Cognitive Science from IIT Kanpur in India. Her primary area of interest being human memory and learning, she is also interested in the neuroscience of cognitive processes. She also identifies herself as a bibliophile and a harry potter fanatic.

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