Screenshot from a video showing the robot in action. Tirado J. et al/YouTube
Researchers from the University of Southern Denmark (SDU) have developed a bioinspired soft robot that mimics the movement of limbless animals. Inspired by creatures like snakes and worms, the robot can easily traverse flat and obstacle-filled surfaces.
Alongside a paper published in the journal Cyborg and Bionic Systems, the team also released footage of the robot in action. In the video, the robot can be seen bending its “body” in a fashion strikingly similar to the limbless animals it was designed after.
The robot is also surprisingly fast for its size, with test footage showing it capable of travelling in a straight line up to 0.03 mph (11.09 millimeters per second). That might not sound fast, but to put it into perspective, your typical earthworm can achieve speeds of somewhere in the region of 20mm per second.
Other parts of the footage show the robot navigating fairly complex environments as well. One particular experiment shows it can easily tackle an obstacle course with its relatively tight “turning circle.”
Soft robot inspired by nature
According to the research team, the robot can move by using its body to gain traction with the ground. This is accomplished, according to the researchers, by using inflatable soft actuators arranged in an antagonistic manner (working against each other).
Along with its skin, this simulates the earthworm’s ability to move using a phenomenon known as anisotropic anchoring. In the case of worms, this involves the presence of tiny appendages on the animal’s skin called setae, which help it gain purchase on a surface and enable movement.
The body itself is also covered in a kirigami skin, which is a patterned, flexible material that creates asymmetric friction. This enables the robot to apply different resistance in different directions, much like an earthworm’s setae.
Using these features, the robot can replicate something called rectilinear motion (straight crawling), which is achieved by inflating chambers in sequence. Steering is accomplished through asymmetric gaits, which allow for rotation or turning.
Regarding navigation, the robot features a suite of onboard proximity sensors to detect and analyze its surroundings. Actual command and control are provided via a human-machine interface (HMI) that allows a human to guide or adjust movement in real-time.
Potential applications out of the lab
Its adaptability was demonstrated through successful maneuvering around coarse substrates and solid obstructions, highlighting the potential for autonomous exploration in unpredictable settings.
The design also emphasizes mechanical compliance, allowing the robot to deform in response to pressure rather than break, a vital trait for navigating collapsed buildings or pipes.
This development is not just interesting for its own sake, but could have some critical applications when fully fleshed out. For example, it could provide search-and-rescue operations in rubble, explore confined areas, monitor environments, or inspect hard-to-reach industrial spaces.
Future iterations could integrate autonomous decision-making or AI-driven pathfinding, potentially eliminating the need for human oversight.
The study, “Multimodal Limbless Crawling Soft Robot with a Kirigami Skin,” can be found in the journal Cyborg and Bionic Systems.
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