Inspenet, October 8, 2023.
This robot provides hope in device reduction.
A group of researchers led by Robert Shepherd, from Cornell University in New York, developed an actuator that uses a combustion chamber manufactured by 3D printing and weighs just 325 milligrams. This actuator works by generating a spark between a pair of electrodes, which ignites a mixture of methane and oxygen . The resulting explosion exerts a force of 9.5 newtons on a flexible membrane.
The team has chosen methane as an energy source , as it is a chemical fuel capable of storing energy much more densely than lithium-ion batteries, allowing the devices to be reduced to dimensions similar to those of an insect.
The membrane expands rapidly outward with each explosion, but safely contains the gases, which are gradually released as it contracts. This actuator is capable of generating up to 100 explosions of this nature per second. In durability testing, one of the actuators successfully withstood 8.5 hours of continuous operation, for a total of 750,000 successful explosions.
From actuator to robot
The team then designed a prototype quadruped robot that incorporates two of these combustion chamber devices, each connected to a pair of expandable membranes on its legs. Fuel was supplied remotely through thin pipes. Test results showed that the robot had the ability to move loads that were 22 times its own weight, suggesting the possibility of using onboard fuel in future applications.
The robot , with dimensions of 29 millimeters long and a weight of 1.6 grams, has the ability to perform jumps reaching heights of up to 56 centimeters, advancing 16 centimeters. In addition, it can crawl or jump on various surfaces at speeds up to 16.9 centimeters per second, achieving turns in any direction by activating a single combustion chamber at a time.
The team notes that the ability to quickly generate large force at a tiny scale not only has applications in robotics, but could also be useful in devices such as pumps and automated laboratory equipment. However, a significant drawback stands out when using explosions to power robots: the noise they generate is high.
” There are many places where this would be useful that would not be next to a person ,” he says. “ In fact, I think this would be a solution for search and rescue and operations in austere and remote environments like space, like water .”