Foldable Joints for Foldable Robots

Print-and-fold manufacturing has the potential to democratize access to robots with robots that are easier to fabricate using materials that are easier to procure. Unfortunately, a lack of understanding about how motion can be achieved by folding hinders the scope of print-and-fold robots. In this paper, we show how the basic joints used in robots can be constructed using print-and-fold. Our patterns are parameterized so that users not only get the desired degrees of freedom but can also specify the joint's range of motion. The joints can be combined with each other to achieve higher degrees of freedom or with rigid bodies to produce foldable linkages. We have folded our basic joints and measured their force–displacement curves. We have composed them into joints with higher degrees of freedom and into foldable mechanisms and found that they achieve the expected kinematics. We have also added actuators and control circuitry to our joints and mechanisms, showing that it is possible to print and fold entire robots with many different kinematics using a uniform process.