Researchers at Tokyo University’s Graduate School of Information Science and Technology have developed a robotic arm in the shape of an ostrich’s neck. The artificial arm can be twisted to get into hard-to-reach places. The manipulator, called RobOstrich, moves neighboring joints one after the other and thus creates a rolling movement pattern.
Birds’ necks are highly flexible so they can groom themselves better or look in different directions in flight. The ostrich has a particularly robust and dexterous neck. The Japanese scientists have therefore taken it as a model for their robotic arm, as described in the scientific paper “RobOstrich” Manipulator: A Novel Mechanical Design and Control Based on the Anatomy and Behavior of an Ostrich Neck” describe which is published in IEEE Robotics and Automation Letters.
Developing robotic arms that have as many degrees of freedom as possible is a challenge. “From a robotics point of view, it is difficult to control such a structure,” explains Kazashi Nakano, a doctoral student at the Graduate School of Information Science and Technology. “We focused on the ostrich neck because we can discover something new there.”
Recommended Editorial Content
With your consent, an external YouTube video (Google Ireland Limited) will be loaded here.
Always load YouTube video
The RobOstrich manipulator still moves a little awkwardly, but is already showing its potential.
To do this, the research team first dissected the neck of an ostrich in order to understand its structure of tendons, muscles and bones. The researchers wanted to know exactly how it is possible to move a body part weighing around three kilograms so flexibly. The ostrich neck has 17 vertebrae including the shaft and atlas – more than twice as many as humans with their seven cervical vertebrae. The vertebrae in an ostrich can be twisted in two directions, which leads to extremely high degrees of freedom.
Difficult to control
After their observations, the scientists set about building the RobOstrich arm based on this model. To do this, they printed out 17 vertebrae using a 3D printing process, which they connected with bearings. They used piano strings to replace the muscles between the ostrich vertebrae. They used rubber bands at the base of the manipulator to create tension. An electric motor is used to wind the wires, creating enough tension to flex the robotic arm’s muscles.
Together with a simple gripper, RobOstrich is able to carry out various gripping tasks. Similar to a real ostrich neck, a rolling movement pattern is generated. Adjacent joints move in sequence while the head remains level with the ground. This movement pattern is achieved by merely tensioning the wires on the underside of the artificial neck, while the length of the wires on the back remains the same, so there is no need to pull. The RobOstrich manipulator can thus carry out complex actions with minimal effort.
Nakano admits that this very flexible structure is difficult to control. However, due to the skillful arrangement of muscles and joints, there are a number of skillful gripping movements.
At the moment, however, this is still working a bit awkwardly and only forwards in a two-dimensional plane. The researchers are now working on redesigning the manipulator so that it can move in three dimensions. To do this, they want to develop a controller that also enables gripping movements in unstructured environments.
(olb)
