Masha Shugrina, an MIT graduate student in computer science and engineering and one of FabForms’designers, said: “The question we set out to answer was, ‘How do you allow people to modify digital designs in a way that keeps them functional?’”
For a CAD user, modifying a design means changing numerical values in input fields and then waiting for as much as a minute while the program recalculates the geometry of the associated object.
Once the design is finalised, it has to be tested for structural stability, integrity and whether it complies with the printer’s specifications using simulation software. Those tests can take several minutes to several hours, and they need to be rerun every time the design changes.
Fab Forms begins with a design created by a seasoned CAD user. It then sweeps through a range of values for the design’s parameters calculating the resulting geometries and storing them in a database. For each of those geometries, the system also runs a battery of tests, specified by the designer, and again storing the results. The whole process would take hundreds of hours on a single computer, but in their experiments, the researchers distributed the tasks among servers in the cloud.
Finally, the system generates a Web page that can be opened in an ordinary browser. The interface consists of a central window, which displays a 3D model of an object, and a group of sliders, which vary the parameters of the object’s design. The system automatically weeds out all the parameter values that lead to unprintable or unstable designs, so the sliders are restricted to valid designs.
“Autodesk has simplified version of this project,” says Ryan Schmidt, head of the Design and Fabrication Group at Autodesk Research. “Project Shapeshifter is similar to these geometry generators that have a parametric model you can explore. But they have a common problem: that you can make something that won’t work on your printer.
“What I thought was exciting about this work is that it can prevent you from designing something that isn’t going to print or that isn’t going to be strong enough once you’ve printed it.”
