Professor Youngsu Cha and his research team at the Korea University School of Electrical Engineering have developed a hybrid quadruped robot capable of traversing steep slopes and uneven terrain with ease. By integrating a foldable leg-assisted system, the team overcame the limitations of conventional wheeled robots, opening new possibilities for locomotion over complex surfaces.
 

Conventional wheel-based robots have seen broad applications in transportation, surveillance, and exploration thanks to advances in AI and precision control. However, they struggle on rough or inclined surfaces. To address this challenge, the research team proposed a Foldable Leg Assistant (FLA) system, which employs a Variable Stiffness Structure (VSS)—a mechanism that allows the robot to adjust its rigidity in response to external forces or stimuli. This enables the robot to lift or tilt its body autonomously, allowing the wheels and legs to work in complementary coordination for complex terrain mobility.
 

The FLA-equipped robot demonstrated the ability to lift its body by approximately 23% of its total height and successfully climbed slopes as steep as 73 degrees, surpassing the limits of existing wheel-based designs. Experiments further confirmed that the robot achieved stable locomotion with a 90% success rate across various terrains, including platforms and gravel surfaces.
 

The team also applied the same variable stiffness mechanism to a foldable robotic arm equipped with a camera, enabling the robot to inspect confined or hard-to-reach environments such as drainage systems and narrow gaps. Moreover, they designed a soft robotic gripper capable of delicately handling irregular or fragile objects—such as fruits and food items—demonstrating strong industrial potential.
 

Professor Cha stated, “This research demonstrates how soft and flexible foldable structures can complement and enhance the performance of conventional rigid robots. We expect our findings to inspire new directions in the design of multifunctional robotic systems with enhanced adaptability and functionality.”
 

This research was published online on October 6 in Advanced Science (Impact Factor: 14.1), a leading international scientific journal.