UNIST researchers design easy way to make soft robots made of flexible materials

SEOUL -- Robots in everyday life, such as nursing and pet robots, need soft and flexible characteristics. There is a high interest in soft robots made of flexible materials, but it is difficult to implement a complex driving system with flexible materials. South Korean researchers have developed an easy way to make soft robots that are flexible and strong.

A research team from Ulsan National Institute of Science and Technology (UNIST) demonstrated a starfish robot using tensegrity (tension + integrity) structures, which are widely used in long-span space structures in civil engineering due to controllability, reliability and flexibility. The production of a starfish robot that can shrink and unfold on its won is possible by using smart magnetic materials.

"This study is meaningful in developing a technique to quickly and easily implement tensegrity structure in the desired form, and will greatly help develop soft robots with various shapes and functions in the future," said Kim Ji-yun, a UNIST professor of material science and engineering.

Tensegrity structure provides both structural integrity and flexibility through the combination of stiff struts and a network of flexible tendons. The integration of smart materials into tensegrity structures would provide additional functionality and may improve existing properties, but manufacturing approaches that generate multi-material parts with intricate 3D shapes suitable for such tensegrities are rare.

"The structural complexity of tensegrity systems fabricated through conventional means is generally limited because these systems often require manual assembly," the UNIST team said in a research paper published on the website of Science Robotics, a science journal.

"We report a simple approach to fabricate tensegrity structures made of smart materials using 3D printing combined with sacrificial molding. Tensegrity structures consisting of monolithic tendon networks based on smart materials supported by struts could be realized without an additional post-assembly process using our approach," the paper read.

"We demonstrated a tensegrity robot capable of walking in any direction and several tensegrity actuators by leveraging smart tendons with magnetic functionality and the programmed mechanics of tensegrity structures. The physical realization of complex tensegrity metamaterials with programmable mechanical components can pave the way toward more algorithmic designs of 3D soft machines."