Foldable Joints for Foldable Robots

Print-and-fold approaches to robot fabrication allow entire robots to be produced using a single uniform process: fabricating them in-plane and then folding them into their 3-D forms. Current efforts to design print-and-fold robots have been limited by a lack of understanding of what motions can be achieved by folding. In this paper, we introduce fold patterns for three basic joints commonly used in robots, and we show how the patterns can be changed to accommodate user-specified ranges of motion. The joints are composed with each other to produce joints with higher degrees of freedom and with rigid bodies to produce entire foldable linkage mechanisms. We have folded our basic joints and composed mechanisms, and they achieve the expected kinematics. We have also printed control circuitry on and attached actuators directly to three of our designs, demonstrating that it possible to print and fold robots with many different kinematics.