IST Austria Researchers Develop CurveUps: Self-Actuating 3D Printed Objects

We’ve heard of 3D printers being used to draw in 2D, but what about taking a 3D model and transforming it into a 2D template? That’s what a group of researchers with the Institute of Science and Technology (IST) Austria are attempting to do in their research on self-actuating objects, which are essentially flat materials that use material forces to transform themselves into 3D objects. The group of current and former IST Austria computer scientists not only figured out a way to create smooth, self-actuating, free-form objects, they also developed a unique material design and a new self-transformation method.

Until now, the range of self-actuating objects was fairly limited to objects with sharp edges and hardly any curvature, while methods of transformation were mostly based on folding, or other processes, like inflation and chemical reactions, that could not be precisely controlled. But the IST Austria research group designed flat sheets that can change themselves into free-form, smooth-surfaced 3D objects, which they call CurveUps.

“There is a great deal of knowledge in terms of 2D printing technology, and we connect these capabilities with those of 3D objects,” explained Bernd Bickel, Assistant Professor at IST Austria and team leader. “This is an extremely exciting area of 3D printing research, and the group is actively working to expand the possibilities even further.”

The other team members include third year Computer Graphics and Digital Fabrication PhD student Ruslan Guseinov and Eder Miguel, previously a postdoctoral student with IST Austria, now a postdoc at Rey Juan Carlos University.

The team was able to work out the computational tools necessary to take a user-provided 3D model and use it to automatically create a 2D flattened template, which then transforms into the original 3D version once it’s released. It’s difficult to get a final 3D object which is mechanically stable, but the team got around this by developing a controllable mechanism.

Guseinov said, “I experimented with so many different materials and methods before coming up with our current design.”

Tiny tiles, sandwiched between pre-stretched layers of latex, make up the CurveUps. While the CurveUps are transforming, the tension in the latex pulls these tiles together, and joins them all into one continuous shell. The team published their research in a paper, titled “CurveUps: Shaping Objects From Flat Plates With Tension-Actuated Curvature,” in ACM Transactions on Graphics.

The abstract reads, “We present a computational approach for designing CurveUps, curvy shells that form from an initially flat state. They consist of small rigid tiles that are tightly held together by two pre-stretched elastic sheets attached to them. Our method allows the realization of smooth, doubly curved surfaces that can be fabricated as a flat piece. Once released, the restoring forces of the pre-stretched sheets support the object to take shape in 3D. CurveUps are structurally stable in their target configuration. The design process starts with a target surface. Our method generates a tile layout in 2D and optimizes the distribution, shape, and attachment areas of the tiles to obtain a configuration that is fabricable and in which the curved up state closely matches the target. Our approach is based on an efficient approximate model and a local optimization strategy for an otherwise intractable nonlinear optimization problem. We demonstrate the effectiveness of our approach for a wide range of shapes, all realized as physical prototypes.”

Once the team developed the design and transformation method, they worked on creating tools to make the 2D templates for printing. The IST Austria team’s program automatically generates a 2D tile layout, including the location, orientation, and shape of each tile and connecting pins, from a user-supplied 3D form. But this would obviously be a huge optimization problem, and nearly impossible to complete on a personal computer, as even small models can have hundreds, or even thousands, of individual tiles. So the group figured out a two-step optimization process: it gives an approximate solution first, then performs any local refinements needed before making the final template. You can view the procedure, from 3D model to a CurveUp, in the video below.

Guseinov explained, “Our research is a step toward the development of new fabrication technologies: there have been many advances in flat fabrication, for instance in electronics, that have previously been limited to 2D shapes. With CurveUps, we make it possible to produce 3D objects empowered with these same technologies, pushing the limits of digital manufacturing far beyond the current state.”

Next month, the IST Austria research team will present their paper at SIGGRAPH 2017 in Los Angeles, one of the premier conferences in the world on computer graphics and interactive techniques. Discuss in the CurveUps forum at 3DPB.com.