Interview with Hyungsoon Park, Professor at the Department of Mechanical Engineering at KAIST

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When Professor Hyung-Soon Park was a Ph.D. candidate at the Department of Mechanical Engineering at KAIST, it occurred to him one day: “Will my life be different when I make nice robots or become good at controlling them? I don’t think I’m helping anyone. Why should I continue this study?” These questions prompted him to pursue the field of rehabilitation robotics. Developing various robots to help the physically challenged, Professor Park turned his attention to using a treadmill, a machine traditionally used for physical training, as a more effective tool for walking rehabilitation training. After a long period of research, he finally upgraded the treadmill’s performance.

“Many researchers are interested in ‘being the first.’ So, they make new attempts with novel ideas and publish their papers. However, my research philosophy is to ‘do what can become available right now.’ So, my lab is engaged in R&D efforts for what can be readily usable.”

  • New treadmill combining innovation and universality

Traditional walking rehabilitation training involves physical therapists assisting patients. Treadmills for constant walking are also used for walking rehabilitation, but they demonstrate meager effects compared to training in which physical therapists participate in person. This is because, while therapists can accommodate patients by directly checking the condition of each patient, conventional treadmills are not designed to sufficiently reflect patient condition or personal demand.

“However, as a means for rehabilitation training, treadmills themselves have many merits such as safety and accessibility. I began this research in 2011, when Dr. Pam Duncan reported far-reaching research results comparing the rehabilitation effects of skilled physical therapists against treadmills in the United States. The results showed that physical therapists proved far more effective. That’s when I began to explore ways to make existing treadmills much more effective by maximizing their advantages.”

Prof. Park focused on implementing a realistic feeling of walking into treadmill rehabilitation by devising a method of moving the treadmill in response to the walker’s speed.

“First, we developed a controller to make the treadmill respond to the speed of the walker. Based on multiple studies, we decided to focus on the fact that the maximum speed of a foot swung while walking is proportionate to the walking speed. So, we installed cameras around the treadmill to analyze motions. We also developed a sensor to check each foot’s swing speed with the cameras and identify the user’s intent to change the walking speed.”

The innovation and universality embodied in this new treadmill stood out in the next stage. The treadmill developed by Professor Park is 1.5m long, as is the case with general treadmills. This short treadmill is able to swiftly understand the walker’s intent to change speed and readily change the walking speed on the treadmill just as a walker changes walking speed on the ground. Further, the first models of motion analysis cameras were quite expensive, but the currently used models only cost about 200,000 to 300,000 won, thanks to ideas contributed by students participating in the research project. Compared to similar constant-walking treadmills developed in other countries, with lengths of 2-8 meters and costing several million dollars, Professor Park’s treadmill represents remarkably innovative improvements of existing technology.

In addition, this treadmill uses virtual reality to allow for curved walking with the straight rail. “We used a little trick. When you walk while watching the screen installed on the front side of the treadmill, the virtual reality technology produces the display angle depending on which direction you watch. That way, you could feel as if you’re walking along a curved path. Parkinson’s disease patients are prone to falling down while curved walking, and our treadmill offers a perfect environment for their training.”

  • KAIST END RUN Seed Project to enable free, goal-oriented research

Professor Park participated in the KAIST END RUN Seed Project to receive support in the process of making his new treadmill into popular models. Seoul National University Bundang Hospital partnered with him to apply the treadmill in its clinical practice, and Professor Park improved the technology based on the actual clinical cases. As a result, this treadmill technology operates only with the servo-motor installed on general treadmills, as well as motion analysis cameras, sensors, and screens to show virtual reality.

“While participating in the KAIST END RUN Seed Project, I realized that this project was consistent with my research philosophy, which is to do what can become readily usable. I enjoyed working with the project as my philosophy was in harmony with the project’s goal of assisting commercialization of promising technologies. Also, this project is self-driven and goal-oriented. It requires minimum paperwork, so researchers can enjoy more autonomy. The final presentation was very efficient as well as it only asks the researchers to demonstrate key points to the evaluators within five minutes.”

  • Message for rehabilitation robotic engineers

Professor Park’s treadmill features outstanding technology, but it also carries profound meaning. “I believe this treadmill’s upgraded performance sends a message to engineers working in rehabilitation robotics. Many robotic engineers tend to put robots first when they try to make robots help people. However, I‘m confident that the top priority should be people. If robots are not the best solution to the problem, they should consider giving up expensive robots and finding the best solution. This treadmill combined technologies oriented towards human beings and was made available for all patients. I wish this message could facilitate development of technologies, at least in the field of rehabilitation robotics, to place people first.”

  • A single goal to help those who are physically challenged due to brain diseases

This new treadmill demonstrated its effect in recovery of walking symmetry, one of the yardsticks to measure the efficacy of walking rehabilitation training. Also, it obtained particularly favorable results in brainwave tests. Compared to existing treadmill training, Professor Park’s treadmill contributed to remarkably high brainwave activities during walking training. This outcome indicates that training based on each walker’s own pace and volition is of significant importance for recovery of brain functions.

“Currently, our lab is greatly interested in brainwave studies. If we can discover which rehabilitation training is more effective based on those brainwave studies, I believe we will be able to develop training equipment and programs perfect for each user.”

The treadmill upgraded by Professor Park is heading toward the next level. Mr. Park’s lab is working to prove the treadmill’s performance through long-term clinical tests. He has only one goal: to help those who are physically challenged his dream come true and bring a bright future for many patients who want to recover their walking abilities.

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