A new design from a group of Harvard engineers demonstrates how 3D printing can improve soft robotics. Most of today’s robots are metal, and for good reason—they are fast, precise, and powerful. Hard bodies are logical homes for the metal electronics that are required for sophisticated autonomous machines. However, metal robots are inflexible and fragile. Soft robots, on the other hand, are adaptable and resilient. Unfortunately, they are also slow and difficult to fabricate. Most importantly, soft materials aren’t good at protecting the hardware that is required for autonomous robots. Now that new materials can be 3D printed, Harvard researchers created a robot that combines the best of both options, with a rigid core that gradually transitions to a soft body.
Previously, the abrupt transitions from hard to soft material was a frequent failure point for soft robots. The Harvard researchers solved this challenge by using a 3D printer to construct a body with varying degrees of hardness. They mixed several materials in different ratios to create a range from rigid to soft in one continuous print job. At the center of the body, a stiff cage contains a battery, computer, and materials for the combustion system to propel the robot. The cage is surrounded by a semisoft shield, which is then surrounded by a soft outer body.
To move, the robot inflates its three pneumatic legs to tilt the body in the right direction, then butane and oxygen mix, a pair of wires spare the fuel ignition, and the robot propels into the air. The robot can jump half its width forward and as high as up to six times its body height. The researchers performed stress tests that revealed that the gradual hard-to-soft robot was much better at surviving falls than a harder version and it protected the inner electronic guts better than a completely soft robot did. The project was supported by the National Science Foundation and the Wyss Institute, and is published in the July 10 issue of Science.
The robot should perform well in harsh conditions such as disaster zones, because it can jump around obstacles and survive unexpected falls. It would do better than hard robots in harsh terrain because it doesn’t have any sliding parts or joints that could get clogged with debris. “The robot’s stiffness gradient allows it to withstand the impact of dozens of landings and to survive the combustion event required for jumping. Consequently, the robot not only shows improved overall robustness but can locomote much more quickly than traditional soft robots,” said researcher Nicholas Bartlett.
Harvard’s Office of Technology Development has filed for a provisional patent on the technology and is pursuing commercialization opportunities. The researchers were able to take their ideas from concept to reality quickly and cheaply, thanks to 3D printing. As new materials continue to become available for 3D printing, more engineers will be able to design and test prototypes faster and cheaper than ever before. As 3D printing becomes even more widespread, creative engineering should lead to many improvements in technology.