My foot lifted on its own. With just a slight motion as if to walk, I was stepping onto an uphill mountain trail. A wearable robot device strapped to my waist and legs detected and analyzed my movements, then added power to the next predicted motion. It felt as if my legs were moving automatically.
I climbed Cheonggyesan wearing the HypershellX Ultra, a wearable robot from the Chinese robotics startup Hypershell that uses artificial intelligence (AI) to match the user's movements and augment power and control at needed moments.
Hikers started showing interest one by one from the moment I put on the device at the entrance before the hike. Some, curious, asked what it was, while an older man chided, saying, "Why wear something like that when you're coming to the mountain to exercise?" When asked if it really works, I finished strapping in, saying I was about to find out.
You wear the machine by strapping the part with the battery and motor around your waist like a belt and wrapping bands around both legs. Remembering an employee's advice that wearing it in the exact position maximizes the effect, I took care to fit it properly. I tightened the belt to fit snugly to my pelvis and waist, and fixed the leg bands 1–2 cm above the knees. It took about five minutes to power it on and sync it with the preinstalled app.
At 1.8 kg (excluding the battery), the weight was not a major burden. Because the battery sits at the back of the waist, wearing a backpack was difficult. On the other hand, when sitting to rest or bending forward, there was nothing in front of my abdomen, so wearing the device did not feel inconvenient.
Cheonggyesan stretches 4,000 meters from the entrance to the peak, with an elevation of 616 meters. I started in the lower-intensity eco mode and, after walking a bit, switched to hyper mode. It wasn't a dramatic difference, but the assistive push grew stronger.
Even though I kept it as close to my legs as possible, at first the sensation of having my legs lifted felt awkward. Recalling that it takes time for the device to optimize to my movement patterns, I decided to entrust my body to the machine.
After passing the halfway point and entering a section where the slope gradually steepened, I started to feel the effect bit by bit. In particular, on stretches with continuous stairs, power transfer was good enough that I sometimes bounded up several steps at once. Because the AI predicts the user's movements and augments power, it seemed to optimize energy transfer on stairs with regular spacing rather than on dirt paths.
As we neared the peak and my companion of similar fitness began to slow, I was able to keep climbing without stopping at about the same pace as at the start by splitting the effort with the robot. I had heard that a delivery worker actually bought one; it likely helped that person too.
Near the summit, the attention of tired hikers poured in. They started with, "Does that really help?" and went on to ask about the price and how it works. When I asked in return whether they would buy one to try it, some shook their heads.
It helped on the descent as well. When I tried to go fast on the way down, my knees or ankles would always get strained, but the robot seemed to absorb that impact instead. Sensing the downward motion, the power previously used to lift my leg was used to stabilize my knee. To compare directly, I took off the device; my body instantly felt lighter, but my legs felt that much heavier, and the load on my knees felt much greater.
By the time I finished the descent, which took about three hours, the battery had about two bars left. Counting walking and running on other days as well, it ran out after roughly six hours of use. You can swap in an extra battery, but for activities like trekking where carrying spares is hard, that's something to consider. According to Hypershell, one charge can cover up to 30 km.
Reactions around me to a device offering convenience to humans were a mix of expectation and regret. A person surnamed Yoon, 35, who said they tried it at a pop-up store, said, "It seems it would help in daily life, such as when lifting heavy loads, but a price in the 3 million won range is a burden," adding, "If the rental price is reasonable, I would consider using it."
A person surnamed Song, 68, a climber I met that day, said, "It's a real mountain if you're out of breath and your legs hurt when you get to the top," adding, "I'm curious, but I don't think I'd bother using it."
A person surnamed Lee, 49, who works at the same company, put on the device, went up and down five floors of stairs, and said, "It would be very useful if I bought it for my father, whose strength has greatly weakened. It definitely takes less effort," but added, "However, if he wears this all the time, he won't get exercise, and his muscles might deteriorate further, so we'd need to think more about it."