Birds are able to do a lot thanks to their highly flexible necks, whether it be turning their heads around to groom their backs, looking in many different directions during flight, or accessing hard-to-reach nooks and crannies along the ground or in trees. Among all avian species, the ostrich stands out as one bird with a particularly sturdy and dexterous neck—qualities that are also appealing for robotic manipulators.
Using an accurate blueprint of the muscles and tendons in an ostrich’s neck, researchers in Japan have created a novel robotic manipulator called RobOstrich. They describe the device in a study published 6 April in IEEE Robotics and Automation Letters.
Researchers are interested in creating soft and flexible robotic manipulators that could easily bend into hard-to-reach places, but this comes with challenges. “From a robotics perspective, it is difficult to control such a structure,” explains Kazashi Nakano, a doctoral student at the Graduate School of Information Science and Technology at the University of Tokyo. “We focused on the ostrich neck because of the possibility of discovering something new.”
His team first dissected the neck of an ostrich to understand the underlying network of tendons, muscle, and bone that helps manipulate such a long and heavy body part, which weighs in at a hefty 3 kilograms. Whereas a human has seven vertebrae in the neck, an ostrich has more that double that. What’s more, each cervical vertebra bends in two directions, resulting in extremely high degrees of freedom.
Using this anatomical data, the researchers set about creating their RobOstrich manipulator by 3-D printing 17 vertebrae, which they connected with bearings. Bundles of piano wires were used to mimic the biological muscles between an ostrich’s vertebrae (intervertebral muscles), and rubber bands were used as ligaments at the base of the manipulator to provide tension. An electric motor then reels in the wires, generating tension to “flex” the manipulator’s muscles. In a series of experiments, RobOstrich was able to complete various reaching tasks, where it had to achieve different configurations in order to come into contact with an object.
Just like a real ostrich neck, the RobOstrich manipulator achieved a “rolling pattern,” where adjacent joints move in sequence while the head remains level with the ground. Nakano says he was surprised to find that this movement pattern can be achieved simply by adding tension to wires on just the underside of the neck alone, while the length of the wire on the backside remains constant—that is, it doesn’t need to be pulled. In this way, the manipulator can achieve complex configurations with minimal effort.
“The flexible structure is difficult to control, but the advantage is that dexterous reaching movements can be achieved by introducing muscle arrangements and joint ranges of motion based on the ostrich’s anatomy,” says Nakano.
As currently configured, RobOstrich can only move forward on a 2D plane, but the researchers hope to achieve 3D movement in the future.
“We aim to develop a controller that can perform reaching movements in an unstructured environment while colliding gently with it,” says Nakano.
Meanwhile, RobOstrich is not the only ostrich-inspired robot making headlines. Ostriches can also run at astounding speeds—covering 100 meters in just 5 seconds. Inspired by this feat, researchers at Oregon State University created Cassie, a two-legged speedster. Last September, Cassie set new records for the fastest bipedal robot; you can watch the video here.
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