Researchers taking inspiration from one of the savannah’s most beloved animals have designed a 3D printable lattice structure that allows for more seamless movement in robots.
The team from the Swiss Federal Technology Institute of Lausanne mimicked the musculoskeletal system of elephants which allowed the robot to perform complex movements without the typical “robot-stiffness”.
The musculoskeletal system coordinates the muscles, tendons, ligaments and bones to work together to create smooth movements, something that researchers have previously found difficult to create in robotic structures.
“We used our programmable lattice technique to build a musculoskeletal-inspired elephant robot with a soft trunk that can twist, bend and rotate, as well as more rigid hip, knee, and foot joints,” says postdoctoral researcher Qinghua Guan.
“This shows that our method offers a scalable solution for designing unprecedentedly lightweight, adaptable robots.”
To develop this technology, the team made use of a lattice structure composed of individual cell units made from a simple foam material.
The lattice is 3D printed with 2 main cell types: Body-Centric Cubic (BCC) lattices and X-cubes. The team’s method also allowed them to print hybrid cells, whose shape lies anywhere on the spectrum between BCC and X-cube.
“This approach enables the continuous spatial blending of stiffness profiles and allows for an infinite range of blended unit cells,” says co-author and PhD student, Benhui Dai.
“It’s particularly suited for replicating the structure of muscular organs like an elephant trunk.”
Elephants, like humans, have a mix of rigid bones and loose flexible fat and muscles.
While humans have more than 600 muscles in their entire body, an elephant’s trunk alone has up to 40,000 muscles which allow for enormous strength and dexterity.
By using individual lattice sections allocated to twisting, bending and rotating movements, the robot was also able to replicate the intricate actions of an elephant’s trunk.
The team was able to recreate an elephant’s movements such as the sliding plane joint, which is found in the small bones of the foot, and a bending uniaxial joint like those found in the knee.
“Like honeycomb, the strength-to-weight ratio of the lattice can be very high, enabling very lightweight and efficient robots,” explains Assistant Professor Josie Huges, who led the team.
Part of what made these lattices so efficient is that each cell’s position within the lattice could be programmed. This meant cells could be superimposed onto each other to create entire new compositions with greater mechanical properties.
The lattice design allows for around 4 million possible configurations with 4 superimposed cells and over 75 million for 5 cells.
Soft robots, which are engineered to be flexible and fluid, have many real-world applications such as in agriculture and disaster zones. They are currently being tested for use in surgery to allow for less intensive and more precise operations.
Hughes says that their technology could offer many exciting possibilities for future soft robotic research.
“The open foam structure is well-suited for motion in fluids, and even offers potential for including other materials, like sensors, within the structure to provide further intelligence to foams.”
The technology is presented in a study in Science Advances,