Researchers have found a way to mimic the remarkable dexterity of the elephant trunk using a surprisingly simple design with just three ‘muscles’. This breakthrough could lead to more versatile and efficient robotic systems.
Understanding the Complexity of the Trunk
A wonder of nature, the elephant trunk has a complex and versatile anatomy. There are 17 muscles (8 per side plus another one for the nasal cavity) and tens of thousands of muscle fibers being controlled by up to 60,000 facial neurons, which is probably why the proboscis is considered one of the most versatile appendages in the entire animal kingdom!
Elephants perform many functions through their trunks from breathing and smelling to trumpeting, sucking in foodstuff, spraying with water, and even using it as a weapon. It accomplishes this remarkable feat by coordinating a panoply of muscle contractions, tensions, and torsional changes (twisting), most eloquent in stretching.
The physics behind the elephant trunk was a ‘paradigm for control of filamentary shape in a three-dimensional environment’ and they inspired fascination among researchers. In addition, this kind of movement is not uncommon in climbing plants or the arms of an octopus, which can serve as inspiration for the design of adaptable robotic systems.
Minimal Yet Mighty
The research team, including both engineers and mathematicians, wanted to design a physical counterpart of this agility with the fewest number of actuators. The kind of devices that produce a force or displacement on actuation is known as an actuator.
Based on this muscular model, the authors developed a mathematical model for an elephant trunk-like manipulator (herein referred to as ETA ) with longitudinal actuators and helical actuators that mimic longitudianl muscles and visceral muscles respectively.
They calculated that this one longitudinal fiber and two helical fibers design could produce many trunk deformation modes, both in-plane and out-of-the-plane of the curled-up trunk. This provides greater versatility and reach than with three-linear or two-helix designs.
To apply the mathematical model, the researchers built a soft, slim polymer-based cylindrical structure and integrated 3D-printed liquid-crystalline elastomer fibers that curl in response to heat—made of inexpensive and commonly available materials—to act as actuators. Different fibers tended to contract in a specific direction when heated by an embedded copper wire, ensuring that each ‘muscular’ actuator could be controlled individually.
Conclusion
This “simple trunk-like robotic arm” designed by Urbain and colleagues exemplifies how Nature’s solutions could continue to be at the core of their highly adaptable and efficient robotic systems. This breakthrough in robotic manipulation, motion planning, and obstacle avoidance is enabled by simply mimicking three key factors that allow the elephant trunk to achieve its extraordinary dexterity. While the capabilities of the are relatively limited at this stage, the results point to a viable method for unlocking nature’s solutions to designing advanced robots.
