I have this obsession with Star Wars, and this is a natural non life threatening condition. Die-hard fans like me, when the Star Wars Celebration started this year it gave me something to get excited about. The new Trailer was shown AND we got to see the glimpse of the new droid BB-8, and to the surprise of all Star Wars fans it wasn't CGI! For Star Wars fans this was a revelation. We had only seen a glimpse of the robot in the first trailer released last year. It was a rolling robot ball for a body with a robotic head to top it off, and it doesn't fall off and it moves freely. Everyone is scratching their heads wondering how did they do that? As the crowd looked upon it, Abrams explained the reasoning behind the robot, "There were a lot of discussions about how having a CGI BB-8 would be so much easier for shooting," he said. "But we also knew it would be so much better for the film, for the actors, for the set, for the look of it, if it were performed. Neil Scanlan and his unbelievable team ... built and puppeteer-ed BB-8 in the movie and did an extraordinary job, and it was better for the actors and it was better for the film itself." https://www.youtube.com/watch?v=A_K10fX9DSY   Disney recruited a company called Sphero, they designed a rolling ball (Sphero) that was controlled by your phone or tablet and the concept was fascinating. The website shows a video of the little guy rolling around like BB-8. But what about the head? We see that the head is really not attached, or it would clearly not be able to move around. The theory is that there are magnets that allow the head to float a millimeter or so on the surface of the body. That would not account for how it stays on top of BB-8s body when it rolls. Here is my guess. The cap is a second robot: head is a second robot that is remote controlled and that is how the Head of BB-8 looks around. I am thinking the head has a gyroscope or something that tells the head which way is up, and an accelerometer to detect motion. There is a patent from Disney filed for a "Magnetic spherical balancing robot drive" https://www.google.com/patents/US8269447. Now that covers the body of BB-8 now we need to figure out the head. Here is another patent that could possibly be the solution to how the head stay on BB-8 and an explanation. http://www.faqs.org/patents/app/20140345957 "A self-propelled device includes a spherical housing and an internal drive system including one or more motors. The internal drive system acts to provide power to an interior surface of the spherical housing, thereby causing the self-propelled device to move. A biasing mechanism is coupled to the internal drive system and includes a spring and a spring end in contact with the inner surface of the spherical housing. An accessory component magnetically interacts with the biasing mechanism through the spherical housing such that as the self-propelled device rotates along, the accessory component remains stable with respect to the biasing mechanism." While this no solution it adds to the mystery and if this is the shape to come for many toys or upcoming Star Wars movies there is a lot of excitement to come. Star Wars has always been the leader in the field of cutting edge technology and BB-8 is no surprise.