Put these flat cut-outs into an oven, and then watch them fold themselves into little robot-like shapes. Combining new algorithms with self-folding electronic components, researchers have developed a method that could one day be used to create printable robots that can assemble themselves into three-dimensional configurations when heated. MIT News Office reports.
Building on previous work with origami techniques, MIT's Daniela Rus and colleagues demonstrate, in two separate studies, the promise of bakable robots put together using parts produced by 3D printers. The first describes a system that uses a digital file of a 3D shape to generate 2D patterns that can be reproduced by self-folding plastic.
- To precisely control the angles where the heated sheet folds, the team sandwiched a PVC sheet between two films of rigid polyester punctured all over with slits of varying widths.
- When heated up between 55 and 120 degrees Celsius, the PVC contracts and the slits close. Where the edges of the polyester film press up on another, the PVC changes shape.
- The final angle is a function of the difference in the widths of the slits in the top and bottom films.
- For example, if there's a narrow slit in the top film and a parallel, wider slit in the bottom one, then as the PVC contracts, the edges of the top slit will press together and then the entire sheet will bend downward until the bottom edges meet.
So far they've produced an egg, a bunny, a house, and a humanoid-shaped structure (pictured above). The left image shows the self-folding sheet, and the right is a completed self-folded shape.
Their other study explains how to build foldable electrical components -- resistors, inductors, capacitors, sensors, and actuators -- from self-folding, laser-cut materials. These are the electromechanical muscles behind the robots' movements.
- The electronic components are created using a polyester coated in aluminum.
- The sensor they designed looks like a small accordion, where each of the folds contains a separate resistor.
- When the folds compress, the total resistance changes proportionately, producing a measurable effect on the electrical current passing through the sensor.
- In order for the robot to move, the actuator is a foldable coil that's augmented with a pair of iron cylinders, which can be magnetized by an electrical current.
In this video, you can watch robotic components folding themselves up.
"We have this big dream of the hardware compiler, where you can specify, 'I want a robot that will play with my cat,' or 'I want a robot that will clean the floor,' and from this high-level specification, you actually generate a working device," Rus says in a news release. "So far, we have tackled some subproblems in the space, and one of the subproblems is this end-to-end system where you have a picture, and at the other end, you have an object that realizes that picture."
Their next step is to figure out how to get these tools inside the robots, Rus tells New Scientist, "to add the brains to the body."
The work [pdf] was presented at the IEEE International Conference on Robotics and Automation earlier this month in Hong Kong.