A ketchup cap inspired engineers to build a motor-free shape-shifting robot

Engineers at Princeton University, led by Glaucio Paulino, have developed a motor-free robot capable of rolling, crawling and changing shape using a principle inspired by a ketchup cap. The team investigated how ketchup cap hings snap open and stay open in two distinct positions, revealing that curved, folded shells can hold multiple stable shapes without traditional locking mechanisms.

By analyzing the behavior of these curved shells, the researchers created mathematical rules predicting their behavior and used these principles to build a magnetically controlled robot that can change its shape and move without motors or complex internal mechanisms. The ketchup cap's simple design demonstrated that curved shells can naturally settle into multiple stable positions, which the researchers leveraged to create a simpler and more efficient robotic design based on geometry rather than conventional mechanical components.