Researchers from Harvard University and MIT are creating soft robots that can lift objects up to 1,000 times their own weight using only air or water pressure.
While soft robotics has seen major research development and breakthroughs over the last decade, increased flexibility and dexterity has usually meant the use of softer materials, which in turn meant a trade-off of reduced strength and resilience.
The researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), the Wyss Institute at Harvard University and MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have created origami-inspired artificial “muscles” that add strength to soft robots.
According to Daniela Rus, a Professor of Electrical Engineering and Computer Science at MIT and one of the senior authors of the research paper, expressed surprise at the strength of the actuators.
“We expected they’d have a higher maximum functional weight than ordinary soft robots, but we didn’t expect a thousand-fold increase,” Rus said.
Corresponding author of the research paper, Robert J. Wood, a Professor of Engineering and Applied Sciences at the SEAS, says artificial muscle-like actuators are one of the most important grand challenges in all of engineering.
“Now that we have created actuators with properties similar to natural muscle, we can imagine building almost any robot for almost any task,” he explained.
Each artificial muscle consists of an inner 'skeleton' of metal coil or folded plastic sheets. This structure is surrounded by air or fluid and sealed inside a plastic or textile bag.
The muscle moves thanks to a vacuum that is applied to the inside of the bag. This causes the bag to collapse onto the skeleton, creating tension that drives the motion. The muscle’s movement is directed entirely by the shape and composition of the skeleton, with no other power source or human input required.
The engineers point out that the muscles are 'programmable' – designing how the skeleton folds defines the movement of the whole structure. This eliminates the need for a control system, simplifies the algorithms required, and allows the muscles to be very compact and simple, and thus more appropriate for mobile or body-mounted systems.
The researchers have experimented with various materials, different skeleton shapes, and different muscle functionality, ranging from some that can contract down to 10 per cent of their original size, lift a delicate flower off the ground, or twist into a coil.
The artificial muscles are able to generate about six times more force per unit area than mammalian skeletal muscle can, and a 2.6 g muscle can lift a 3 kg object. They are also quick to assemble and cost-effective.