A team at MIT has developed a novel method for designing three-dimensional structures that can be deployed from a flat configuration with a single pull of a string. The technique, inspired by the Japanese art of kirigami, promises to simplify the assembly and transport of complex structures for a wide range of applications, from portable medical devices to emergency shelters.
The core innovation lies in an algorithm that translates a user-defined 3D shape into a flat pattern composed of interconnected tiles. These tiles are connected by rotating hinges, allowing the structure to fold flat for storage and then expand into its intended form when actuated. The algorithm doesn’t just create a foldable pattern; it optimizes the path a string must take to efficiently deploy the structure. It calculates the fewest points the string needs to lift and the shortest route connecting them, minimizing friction during deployment. This ensures a smooth and reliable transition from flat to 3D with a single pull.
Kirigami, the art of paper cutting, served as a key inspiration for the researchers. Unlike origami, which relies on folding, kirigami allows for cuts to be made in the material, enabling more complex and dynamic shapes. The MIT team leverages this principle by creating structures that utilize auxetic mechanisms – materials that become thicker when stretched and thinner when compressed. This property is crucial for efficient folding and unfolding.
“The simplicity of the whole actuation mechanism is a real benefit of our approach,” says Akib Zaman, a graduate student in electrical engineering and computer science and lead author of the research. This simplicity is a significant departure from many existing deployable structures that require complex mechanisms or multiple steps for assembly.
The algorithm operates in two key steps. First, it converts the desired 3D geometry into a flat arrangement of these auxetic tiles. Second, it computes the optimal string path, identifying the minimum number of lift points and the shortest connecting route. This path is designed to minimize friction, ensuring smooth actuation. The process is also reversible, allowing the structure to be easily returned to its flat configuration.
The potential applications of this technology are diverse. The researchers demonstrated the method by creating a human-scale chair that could be assembled and disassembled by one person. Beyond furniture, the team envisions applications in the medical field, such as rapidly deployable splints or other portable devices. Emergency response is another key area, with the possibility of creating flat-pack emergency shelters or field hospitals that can be quickly deployed in disaster zones. The technology could also be used to create foldable bike helmets or robots capable of flattening to navigate confined spaces.
The fabrication of these tile patterns is versatile, accommodating various manufacturing techniques including 3D printing, CNC milling, and molding. This flexibility allows for the creation of structures from a range of materials, tailoring the design to specific application requirements.
Looking further ahead, the researchers suggest the technology could even be adapted for space exploration. Modular space habitats could be manufactured on Earth in a flat configuration and then deployed on the surface of Mars by robots, reducing the logistical challenges of transporting large, pre-assembled structures. The efficient storage and transport offered by this method are particularly valuable in space applications where volume and weight are at a premium.
The development addresses a long-standing challenge in engineering: creating complex structures that are both robust and easily deployable. Traditional methods often involve intricate assembly processes or bulky mechanisms. This new approach offers a streamlined solution, potentially revolutionizing how we design and deploy structures in a variety of fields. The ability to store and transport complex 3D objects in a flat, compact form significantly reduces costs and logistical hurdles.
While the current research focuses on optimizing the string-pulling mechanism, future work could explore alternative actuation methods, such as using shape-memory alloys or pneumatic systems. Further research will also focus on scaling up the technology to create even larger and more complex structures. The team is also investigating ways to automate the design process, making it easier for users to create custom deployable structures without requiring specialized expertise.
