In the realm of miniaturized robotics, finding power sources that pack enough energy for locomotion and agility has been a longstanding challenge. While batteries are efficient and clean for larger robots, their energy density diminishes significantly as size decreases. Researchers at Cornell University, however, have devised a breakthrough solution that leverages the unparalleled energy density of chemical fuels for tiny robots.
Published in the journal Science on 14th September, their innovative approach involves utilizing a miniature internal-combustion engine within the robots. This engine operates on methane vapor and oxygen injected into a soft combustion chamber. A spark ignites the mixture, causing the top of the chamber to balloon upwards like a piston, generating powerful forces through rapid cycles. Two of these actuators, each the size of a quarter of a U.S. penny and weighing just 325 milligrams, can drive a pair of legs, creating an exceptionally potent soft quadruped robot.
One of the remarkable aspects of this technology is its durability, despite the inherently violent nature of combustion. The actuator can withstand actual explosions, thanks to careful design considerations such as a small combustion volume, flame-resistant elastomer material, and an integrated flame arrestor. It can operate continuously for over 750,000 cycles without any degradation in performance.
The researchers have successfully implemented this breakthrough in an insect-scale quadrupedal robot, which demonstrates near-insect level performance. Despite being only 29 millimeters long and weighing 1.6 grams, this tiny robot can jump an impressive 59 centimeters straight up and walk while carrying 22 times its weight.
Looking forward, the researchers are keen on further refining the technology to balance speed and force, enabling robots to perform a range of motions from walking to running and jumping. Moreover, they envision employing aggregates of these small but powerful actuators to serve as variable recruitment musculature in large robots, enabling dexterity and agility in a new league of land-based hybrid machines. This breakthrough opens up exciting possibilities, showcasing the potential for large robots to be powered by thousands of tiny yet potent explosions, revolutionizing the world of robotics.