One difficult challenge in robotics is to make them move smoothly across rough surfaces. Researchers have been experimenting with various methods, including the ones inspired by nature, to make robot movement more flexible.
By taking cues from nature, engineers have created a new centipede-like robot that can easily switch from straight walking to curved motion.
Osaka University researchers successfully demonstrated the new robot's flexible motion. “We were inspired by the ability of certain extremely agile insects that allows them to control the dynamic instability in their own motion to induce quick movement changes,” said Shinya Aoi, one of the authors of this study, in an official release.
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The development of the robot
Centipedes are myriapods with elongated, flexible bodies consisting of numerous segments attached by jointed legs. This gives them the ability to move on diverse terrain easily.
This robotic myriapod, too, has six segments and flexible joints. Each segment is made up of two legs and a motor that allows the flexibility of each leg to be adjusted.
This flexibility of the joints allows for the “pitchfork bifurcation” process, where straight walking becomes unstable. This instability allows the robot to walk in a curved pattern and to move from side to side, just like a centipede. As a result, there is much more stability and maneuverability.
“Because this approach does not directly steer the movement of the body axis, but rather controls the flexibility, it can greatly reduce both the computational complexity as well as the energy requirements,” they explain.
The robot prototype measures 53 inches in length and weighs 9.1 kg. The researchers also tested the robot's curved path movement to reach specific locations, and it was able to navigate successfully.
The researchers intend to test their design in more challenging environments on Earth in the future. If everything goes as planned, this one-of-a-kind robot could help with search and rescue missions as well as planetary exploration.
“We can foresee applications in a wide variety of scenarios, such as search and rescue, working in hazardous environments, or exploration on other planets,” says Mau Adachi, another study author.
Nature-inspired robots may be the future of space exploration. NASA's JPL has been training a snake-like robot that can easily traverse the uneven and unknown terrains of our solar system's celestial bodies.
The results have been published in the journal Soft Robotics.
Study Abstract:
Legged robots have remarkable terrestrial mobility, but are susceptible to falling and leg malfunction during locomotion. The use of a large number of legs, as in centipedes, can overcome these problems, but it makes the body long and leads to many legs being constrained to contact with the ground to support the long body, which impedes maneuverability. A mechanism for maneuverable locomotion using a large number legs is thus desirable. However, controlling a long body with a large number of legs requires huge computational and energy costs. Inspired by agile locomotion in biological systems, this study proposes a control strategy for maneuverable and efficient locomotion of a myriapod robot based on dynamic instability. Specifically, our previous study made the body axis of a 12-legged robot flexible and showed that changing the body-axis flexibility produces pitchfork bifurcation. The bifurcation not only induces the dynamic instability of a straight walk but also a transition to a curved walk, whose curvature is controllable by the body-axis flexibility. This study incorporated a variable stiffness mechanism into the body axis and developed a simple control strategy based on the bifurcation characteristics. With this strategy, maneuverable and autonomous locomotion was achieved, as demonstrated by multiple robot experiments. Our approach does not directly control the movement of the body axis; instead, it controls body-axis flexibility, which significantly reduces computational and energy costs. This study provides a new design principle for maneuverable and efficient locomotion of myriapod robots.
