Engineers Go Neck and Neck with Nature

One of the best sources of inspiration for engineers that are seeking to build better, faster, or more efficient machines is the natural world. By studying the behavior of animals and the way they move, for example, scientists and engineers have been able to create robots that can move more efficiently, better adapt to their surroundings, or perform complex functions that are challenging to design.

Before robots can play a larger role in assisting us in our daily lives, one of the hurdles that needs to be cleared is the development of practical flexible manipulators with a high level of dexterity. Systems proposed to solve this challenge typically rely on manipulators with elastic bodies that are penetrated by a number of artificial tendons that drive movement with the help of an actuator at the base. But these designs lack structural stability, and moreover, only have a limited amount of dexterity and are difficult to control with precision.

A team led by researchers at The University of Tokyo found inspiration in the design of the ostrich’s neck. These birds are capable of accessing hard-to-reach areas, or turning their hands in virtually any direction during flight, thanks to their highly flexible necks. In addition to their noted dexterity, ostrich necks are also known to be very sturdy.

These are exactly the types of traits that an ideal flexible robotic manipulator should have, so the researchers studied it to understand what made it tick. A dissection was performed to better understand the layout of the tendons, muscles, and bones that move this six pound neck with such precision.

The anatomical data gathered was put to use in creating seventeen 3D-printed vertebrae, which were linked together with bearings. Bundles of springy piano wire, in conjunction with an electric motor that can reel them up, served as the muscular system. As for ligaments, some simple rubber bands proved to be sufficient for providing constant tension so that the manipulator, named RobOstrich, did not fall flat on its face.

After constructing the manipulator, it was found that some complex actions could be completed with very simple actuation patterns. For example, a rolling pattern, in which the head remains level, but vertebral joints move in a successive sequence, can be achieved by flexing a single artificial muscle.

A series of experiments were conducted to better understand how the manipulator’s motor patterns relate to movements. The testing revealed that through simple actuations, RobOstrich can move in patterns with the same characteristics as the neck movements of the ostrich. This knowledge was leveraged to demonstrate how the manipulator can realize complex functionality, like reaching for an object.

At present, with just a pair of muscles, the neck can only move in two dimensions. The team is working towards three-dimensional movement for a future version of the manipulator, but the complexity that will have to be introduced to make this happen is not yet fully understood. If they are successful, this platform could serve as the basis for a new generation of flexible robotic manipulators that can perform tasks that were once too challenging to achieve with any practical device.