This device, created using affordable materials and a standard 3D printer, powered a worm-like robot and an artificial bicep that lifted a 500-gram weight 5,000 times without failure.
Northwestern engineers have developed a soft, flexible device enabling robots to move by expanding and contracting like human muscles. This device, called an actuator, created a cylindrical, worm-like robot and an artificial bicep. In experiments, the cylindrical robot navigated narrow, pipe-like environments, and the bicep lifted a 500-gram weight 5,000 times without failing.
The body of the actuator was 3D-printed using common rubber, costing about $3 in materials, excluding the motor. This contrasts with the typical stiff actuators in robotics, which can cost hundreds to thousands of dollars.The actuator could lead to inexpensive, soft robots, safer and more practical for real-world applications. The team emphasised the safety of soft robots in human-centric environments. Inexpensive actuators could make robots more practical and widely used.
Soft Actuators for Robotics
Rigid actuators, long the cornerstone of robot design, lack flexibility and adaptability, prompting exploration of soft actuators. Truby’s team aimed to create materials that move like human muscles, contracting and stiffening simultaneously. The team developed the actuator by 3D-printing cylindrical structures called “handed shearing auxetics” (HSAs). HSAs extend and expand when twisted. Previously, they used expensive printers and rigid plastics, but this time, Kim used thermoplastic polyurethane, a common rubber, making the HSAs softer and more flexible. This allowed fabrication with a standard desktop 3D printer.
Earlier HSAs used multiple motors for actuation, complicating fabrication and reducing softness. Kim improved the design by adding a rubber bellows to a single HSA, driven by one motor. This simplified the process and made the actuator more practical for various robotic systems. The resulting worm-like robot, measuring 26 centimeters, crawled backward and forward at over 32 centimeters per minute. The actuator stiffens when fully extended, similar to human muscles. This feature, often overlooked in soft robotics, enhances the actuator’s utility.
