The “Young Robot Engineer” series is a collaborative project between the Korean Robotics Society and Robot News, aimed at discovering and introducing young robotics engineers who will lead the future of Korea’s robotics industry. The 37th interview features Professor Jang Han-deut (34) of Incheon National University. Professor Jang earned his bachelor’s and master’s degrees in mechanical engineering from Osaka University in Japan before returning to Korea, where he received his Ph.D. from KAIST in February 2019. After serving as a postdoctoral researcher at KAIST, he has been an assistant professor at Incheon National University since September 2019. His primary research interests include Physical Human-Robot Interaction, Variable Stiffness Actuators, Prosthetics, Exoskeletons, Nonlinear System Control Theory, and Bio-signal Processing for Motion Intent Extraction. He received the KAIST Mechanical Engineering Department’s Best Teaching Assistant Award in 2014 and the 30th ICROS Best Paper Award in 2015.
Q. You are currently an assistant professor in the Department of Mechanical Engineering at Incheon National University. Could you introduce the department?
The Department of Mechanical Engineering at Incheon National University is dedicated to the academic principles of mechanical engineering, aiming to cultivate outstanding engineers who will play leading roles in industries, public enterprises, and research institutes. The department focuses on designing and manufacturing various types of machinery that enhance human life. With approximately 600 students, the department is supported by around 20 professors with world-class educational capabilities. The curriculum is rooted in traditional mechanical engineering but has expanded to include advanced interdisciplinary fields such as renewable energy, nanomaterials, and, more recently, robotics and bioengineering. We are particularly committed to nurturing talented students in the field of robotics.
Q. I understand you are currently working on a national research project titled “Development of Next Generation Motion Intention Recognition Technology for Safe Physical Human-Robot Interaction.” Could you elaborate on this research? Also, if you are working on other projects, please introduce them as well.
Since my undergraduate days, I have been deeply interested in prosthetics. During my master’s program, I minored in biomedical engineering and conducted theoretical research on how the dynamic characteristics of the human musculoskeletal system influence motor control. Building on this experience, I began researching technologies necessary for physical interaction between humans and robots during my Ph.D.
My research focuses on two main areas: first, hardware development to create actuators that mimic the compliance of human muscles while delivering high torque with low weight; and second, interface research to accurately recognize human motion intent and relay commands to robots without delay using bio-signal processing. These technologies are essential for advanced prosthetics and have broad applications across various fields. I am committed to continuing this research with a sense of mission.
Q. You received your Ph.D. from KAIST in February 2019 with a thesis titled “Development of Self-stabilizing Variable Stiffness Actuation System with Variable Radius Gear and High Torque Motor.” Could you explain the content of this research?
My research was driven more by a natural science perspective than a purely technical one. To briefly explain, human nerves transmit signals through sodium-potassium ion channels, which, due to the accompanying material transport, are much slower compared to robots. From a control engineering standpoint, such slow speeds should make stable control impossible, yet humans achieve this effortlessly. This led me to hypothesize that the dynamic characteristics of the human musculoskeletal system might inherently stabilize the system, even with incomplete feedback. I termed this “self-stabilization” and mathematically derived the conditions for it.
Surprisingly, I found that the dynamic characteristics of human muscles satisfy these conditions. Through experiments, I developed a mechanical system that meets these conditions, resulting in a Variable Stiffness Actuator (VSA) that can precisely adjust joint stiffness without feedback control or computational devices. This research earned me my Ph.D.
My research approach is often described as unique, as I let hypotheses and experimental results guide my direction. I find beauty in uncovering truths step by step, which keeps me motivated and excited about my work.
Surprisingly, I found that the dynamic characteristics of human muscles satisfy these conditions. Through experiments, I developed a mechanical system that meets these conditions, resulting in a Variable Stiffness Actuator (VSA) that can precisely adjust joint stiffness without feedback control or computational devices. This research earned me my Ph.D.
My research approach is often described as unique, as I let hypotheses and experimental results guide my direction. I find beauty in uncovering truths step by step, which keeps me motivated and excited about my work.
Q. Your primary research interests include Physical Human-Robot Interaction, Variable Stiffness Actuators, Prosthetics, and Exoskeletons within the field of biorobotics. What are the latest trends in biorobotics?
Robotics is a rapidly evolving field with diverse approaches. While it’s difficult to pinpoint the latest trends, a major focus remains on developing robots that ensure human safety during physical interaction. Recent advancements in AI and computational power have led to research leveraging massive calculations to address these challenges. While this is a valid direction, I focus on understanding human motor control principles from a control engineering perspective, applying these insights to robot development.
Biorobotics is a field where researchers explore novel approaches, making it an exciting area with immense potential.
Q. You completed your bachelor’s and master’s degrees in mechanical engineering at Osaka University in Japan before returning to Korea for your Ph.D. at KAIST. What motivated you to pursue robotics?
I was selected for the Korea-Japan Science and Engineering Scholarship Program during President Kim Dae-jung’s administration, which allowed me to study in Japan after high school. I chose Osaka University, renowned for its mechanical engineering and robotics programs. Initially, I was not interested in robotics but was deeply fascinated by differential equations and control engineering. However, witnessing Honda’s humanoid robot ASIMO fall while climbing stairs was a turning point. This incident made me question the field until my master’s advisor introduced me to passive dynamic walkers—simple machines that walk stably without sensors or controllers. This inspired me to hypothesize that the human musculoskeletal system’s dynamic properties might aid control, leading me to pursue robotics.
Q. What do you think are the strengths of Japanese robotics research?
Japan’s robotics research excels in its focus on long-term, curiosity-driven projects rather than immediate practical applications. Many researchers prioritize enjoying their work over meeting short-term performance metrics. This environment fosters experts who lead not only robotics but also broader scientific fields. While Korea’s context differs, I hope for a research culture that supports long-term academic exploration.
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Q. What is the most challenging aspect of your research?
My research often involves formulating hypotheses and adjusting directions based on experimental results. While this approach can lead to breakthroughs, it also means facing frequent setbacks, especially when human experiments are involved. However, I remain committed, driven by a sense of mission and the belief that perseverance yields positive outcomes.
Q. What are your dreams and goals as a researcher?
My goal is to develop robots that match or surpass human capabilities in physical interaction. Key technologies include compliant yet powerful actuators and real-time bio-signal interfaces. Beyond technical achievements, I aim to contribute to understanding human motor control principles through robotics, advancing both technology and scientific knowledge.
Q. What advice do you have for students aspiring to study robotics?
Robotics is an interdisciplinary field that requires knowledge beyond mechanical and electrical engineering, including anatomy and physiology. I encourage students to broaden their perspectives and explore various disciplines, as nature does not confine knowledge to academic boundaries.
Q. What advice would you give for the advancement of Korea’s robotics industry?
While robots like drones and industrial robots have seen commercial success, the industry still has room to grow. Collaboration between academia and industry is crucial to bridge gaps and expand robotics into diverse fields.
Q. Are there any professors or researchers who have significantly influenced your work?
I am deeply grateful to my master’s advisor, Professor Koichi Osuka of Osaka University, and my Ph.D. advisor, Professor Kim Jeong of KAIST. Their guidance and support have been invaluable, and I hope to pass on their wisdom to my students as I embark on my journey as an educator.