The Hop is a robotic suitcase that lets you go hands-free at the airport via the Bluetooth connectivity in your phone, the suitcase can follow its owner all on its own. "Hop is a suitcase that follows the user. Represents the next generation of luggage, the following. The suitcase contains three receivers that are able to receive, identify and triangulate different signals coming from the user's cell phone. A microcontroller interprets these signals calculating the phone's position regarding to the suitcase. The same microcontroller operates a caterpillar system based on compressed air, which follows the user at a constant distance. If the signal is lost the user is alerted by the vibration of the phone and suitcase locks itself. The bags can be programmed to follow one to another or are controlled jointly by the staff that handles the baggage at airports or stations."