Northwestern University engineers have created a novel, reasonably priced robotic actuator that contracts and expands to resemble the actions of human muscles. Impressive capabilities of the actuator are demonstrated by the creation of a cylindrical, worm-like soft robot and an artificial bicep.
In laboratory tests, the cylindrical soft robot demonstrated its ability to navigate tight hairpin curves within narrow, pipe-like environments. Meanwhile, the artificial bicep lifted a 500-gram weight 5,000 consecutive times without failure. The actuators’ bodies were 3D-printed using common rubber, resulting in a production cost of approximately $3, excluding the motor. This is a stark contrast to traditional rigid actuators, which can cost hundreds to thousands of dollars.
The researchers published their findings in the journal Advanced Intelligent Systems, emphasizing the potential of their actuators to make robots safer, more flexible, and practical for real-world applications. Historically, robotic design has relied on stiff actuators, but the limitations in flexibility, adaptability, and safety have driven the search for alternatives.
The team’s design draws inspiration from human muscles, which contract and stiffen simultaneously. They utilized 3D-printed cylindrical structures known as “handed shearing auxetics” (HSAs), made from thermoplastic polyurethane, a rubber commonly used in cellphone cases. These HSAs extend and expand when twisted, enabling unique movements and properties. Unlike previous versions made from rigid materials, these rubber HSAs are softer and more flexible, making them more practical.
Postdoctoral scholar Taekyoung Kim highlighted the innovation, explaining how they made HSAs softer and more durable using a cost-effective desktop 3D printer. The actuator’s design includes extensible, soft rubber bellows that function like a revolving, pliable shaft, driven by a single servo motor to twist and contract or extend.
The team successfully built a soft robot that crawled using just one actuator, showcasing the versatility and potential of their design. The robot, measuring 26 centimeters, could crawl backward and forward at over 32 centimeters per minute. As the actuator extends, both the robot and the artificial bicep become significantly stiffer, enhancing their functionality.
Ryan Truby, a professor at Northwestern, expressed excitement about the future of bioinspired robots, noting that this innovation could enable robots to perform tasks previously considered impossible for conventional robots.
