YouTube hacker James Bruton has been building a pair of Performance Robots. He’s developed puppeteering rigs that enable their human operator to manipulate a small model of the bots to have them move, but one thing they lacked before now is actual grippers. He shows how he was able to add these needed implements in the video below, using some very clever tricks to allow them to grip objects of different sizes with a consistent amount of force.
These compliant robot grippers are fairly simple — in terms of humanoid robots — consisting of dual finger mechanisms that come together and separate in tandem. A servo motor pushes and pulls a linkage assembly that connects the two, using a spring assembly to limit the force exhibited on the object. A Hall effect sensor recognizes when the linkage/spring is stretched out of the range of an internal magnet, allowing it to stop and hold the object in place. Another servo operates the wrist, which lets the hands rotate with respect to the arms.
You can see the robots demonstrated in the latter part of the video, where Bruton squares off with Matt Denton in a robot challenge. The game is to get a set of balls on stands into a box, activating the grippers with switches built into the models. While the bots look fantastic, the operators may actually need a bit of practice!