A year ago, Carl Bugeja started working on a four-legged walking robot named 4B that could fold down into a 6cm diameter ball, or roughly the size of a baseball. Like many projects, this one got shelved for a while, but after a long hiatus, he’s returned to his little robot in order to work out the kinks. The process is shown in the video below, including some early testing; however, before watching it, be warned that he’s saving the final testing until Tuesday, December 17th, so you can check back then or perhaps even subscribe. (UPDATE: This clip has since been uploaded.)
While the payoff doesn’t come until later, the process is quite interesting. 3D-printed parts were produced by Shapeways, such as ball-legs constructed out of thin and flexible Nylon. 12 servos move its four legs using a custom PCB — featuring a BLE module, an IMU and proximity sensors — with gait geometry calculated using inverse kinematics. The ball is designed to walk around or fold up in a standby mode, and Bugeja even hints that if the panels are actuated in the proper order it should even be able to roll.
From the looks of the video, it seems that the major issues are fixed, including a rather “do not try this” modification of the battery to remove its current protection, so it should be ready to walk/roll under smartphone control as promised.
Bujega has made 4B completely open source, with all the files and code available on Hackster.