3D Printed Metamaterial Mechanisms
Lately, the soft robotics field has been seeing more and more that many normally rigid structures and systems (with hard parts like bearings, hinges, levers, etc) can be replaced by compliant mechanisms that provide the same result. A great example is Super-Releaser's own Glaucus robot. While there are many "hard" robotic quadrupeds that can walk, the Glaucus walks while being completely made of super-soft silicone. Compliant mechanisms can have many advantages, however the difficulty comes when designing such a mechanism that will provide the desired feedback consistently and reliably. Researchers Alexandra Ion, Johannes Frohnhofen, Ludwig Wall, Robert Kovacs, Mirela Alistar, Jack Lindsay, Pedro Lopes, Hsiang-Ting Chen, and Patrick Baudisch at the Hasso Plattner Institute have published a new research paper regarding a powerful solution to this problem.
The researchers developed a virtual 3D editor that can generate metamaterial machines for FFF 3D printing. Metamaterials are systems that show novel behavior based on their structure. In this case, substantial movement without normal, rigid mechanisms. The researchers' program allows for a general-purpose approach to making these metamaterial machines. The program functions by creating a 3D form and subdividing the 3D shape into cells. The researchers categorize the cells into to types: solid, rigid cells, called members and soft, more flexible cells, called hinge cells. Member cells consist of boxes with intersecting lines, while hinge cells consist of a variety of shapes that allow for differing ranges of motion. Both cell types can be manipulated to have different elastic properties (e.g. more stiffness or more flexibility). By designating certain parts to be certain cells and by inputing how stress will be applied to the machine, the program will turn the 3D model into a 3D printable metamaterial mechanism.
Additionally, the program has the ability to simulate how the finished metamaterial system will act and the capability to create systems with hinge cells on different axis, allowing for the creation of mechanisms with many degrees of freedom.
According to the researchers, metamaterial mechanisms have numerous advantages over traditional multi-part, multi-material mechanisms. These advantages range from ease of fabrication and assembly to extended lifespan due to there being no friction on any part of the system to wear it down. They do admit that there are limitations to this technology, for example, that these mechanisms are not well suited for small forces and are limited in complexity by the tools being used to manufacture them. As a result of this paper, the researchers believe that we should think of metamaterials less as materials and more as machines. Following this research, they plan to investigate metamaterial mechanisms for embedded mechanical logic.
As mentioned previously, this work is quite analogous to soft robotics, in that it is replacing normally stiff and complex mechanisms with soft and simple ones. As a soft robotics company, Super-Releaser is quite interested in this topic. I personally see a tremendous amount of potential in the patterns used in cells in this research. By only manipulating geometry, further motion could be created for metamaterial mechanisms, such as extension, twisting, or even retraction. Overall, we are excited to see this research and cannot wait to see where it leads.
By Aidan Leitch