Research Team Led by SNU Professor Cho Kyu-Jin Develops “Arm of Gazette Robot”
- Featured on the Cover of “Science Robotics”


▲ SNU Department of Mechanical and Aerospace Engineering Professor Cho Kyu-Jin

 
SNU College of Engineering (Dean Cha Kook-Heon) announces on 14^th that the research team led by Professor Cho Kyu-Jin of the Department of Mechanical and Aerospace Engineering has developed a drone robot arm (“gazette robot arm”) using the origami technology. This research has been featured on the cover of the latest issue of “Science Robotics”.
 
Professor Cho’s team (First Authors: Researcher Kim Suk-Jun and Postdoctoral Researcher Lee Dae-Young; Author: Professor Jung Gwang Pil of the Department of Mechanical and Automotive Engineering of Seoul National University of Science and Technology; Corresponding Author: Professor Cho Kyu-Jin, Designer: Researcher Song Jung-Ryul) proposes a foldable manipulator using the “Variable Stiffness Mechanism” that allows an easy control of the robot arm using a single wire. Team demonstrates new applicability of the origami structure.  
 
The robot arm lightly folds thin and quickly unfolds to stiffen. This technology overcomes the structural limitation of conventional robot arms that make them difficult to hold heavy weight and drive smoothly.
 
The “Variable Stiffness Mechanism,” inspired by origami, constricts the movement of adjacent creases that are perpendicular to each other. Using this mechanism, at deployed state, a lightweight hexagonal structure(40X40X100mm) of less than 30 g can endure a compressive force of maximum 12 kg. On the other, by pulling the wire, lockers detach and the hexagonal structure flat-folds compactly.
 
In the video, drone extends its arms to grab objects placed between narrow gaps and takes footages near tree branches. At folded state when the arms are not in use, the robot stays compact for efficient movement and at deployed state, it demonstrates its outstanding capabilities. Cho’s team successfully defeats the two main constraints, space and weight, of soft robots by adding arms. This achievement is to bring insights to general robotics or structures that are implemented in extreme environments like the poles, deserts, oceans, and space.
 
Professor Cho states, “Soft robots, due to its flexibility, lacked the ability to sustain heavy weight. This robot arm uses the variable stiffness mechanism, something in between soft and hard robots, so that the module stays folded while moving and unfolds to stiffen when required. The material in use is a composite of soft fabric coated with stiff PET film.”
 
Q: How can a single wire control the locking mechanism of a robot arm?
A: This is due to the path that the wire follows inside the arm. A single wire unlocks the variable stiffness mechanism consecutively to fold the arm. When the wire is pulled, the force simultaneously splits between unlocking the mechanism and folding the arm. However, with the locker installed, the force to fold the arm initially interferes destructively and only the variable stiffness mechanism gets lifted. Afterwards, the arm folds. This wire-based mechanism can be applied to a single module, or it can be extended to link 7 to 8 modules like the one seen in the video. When the wire is released, the rubber band inside the arm stretches and lockers are installed by magnets.
 
Who is Professor Cho Kyu-Jin?
He is the head of the SNU Soft Robotics Research Center. Cho has been acknowledged for his research in soft robotics and biomimetic robotics to be awarded the “IEEE RAS Early Career” in 2014. In 2015, he becomes the first in SNU College of Engineering to have his study be published on the “Science” journal with his water strider robots. In 2016, he receives attention at the American Association for the Advancement of Science (AAAS) for his soft wearable robot “Exo-Glove Poly” that can help the disabled to perform everyday tasks. In the April of the same year, Cho has won the “RoboSoft Grand Challenge” held in Pisa, Italy with his “SNUMAX”.
 
[Research Paper]
Link: https://www.dropbox.com/sh/2eyw2mhbb9ujk99/AACM-DE7MAcUUiETaDW0VB5ua?dl=0
 
[Photo]
Link: https://www.dropbox.com/sh/otuxrc4dy1ow2lm/AADfACw3Bkkt9pmExGTcX4ypa?dl=0
 
[Video]
Link: https://youtu.be/GW7D3CjQd-g
 

▲ Drone Extending Its Arms to Grab an Object Placed in a Narrow Space