SNU researchers develop exosuit to help people lift heavy objects
New advances in robotics could help push the limits of the human body, making us faster or stronger. Researchers at the Biorobotics Laboratory of Seoul National University (SNU) have developed an exosuit that corrects a person's posture.
In a recent paper, they described the Movement Reshaping (MR) exosuit, which, instead of enhancing any part of the human body, couples the movement of one joint with another to lock or unlock the movement of that other joint. The suit works passively, without batteries or a motor.
For example, when trying to lift a heavy object from the floor, most of us bend at the waist, a posture that promotes injury. The SNU device blocks the bent-over posture and helps correct it into a safer squat.
The paper states: "The conventional approach to correcting lifting posture, immobilizing vulnerable joints with fixation, is insufficient to prevent back injuries resulting from repetitive lifting. Instead, when lifting small but heavy objects, the entire kinetic chain must interact to achieve a series of squat-lift actions."
“We call our methodology "body-powered variable impedance (resistance)" because we can change the impedance of one joint by moving another”
Most assistive devices, such as Carl Zelik's HeroWear, are designed to reduce user fatigue by providing extra power and minimizing interference with the user's voluntary movements. On the other hand, there is the MR Exosuit, which focuses on converting the user's lifting movements into a safe squat form, as well as providing additional strength.
The MR suit was designed to reduce injuries among workers in factories and warehouses who perform repetitive lifting. Many lifting-related injuries are caused not only by muscle fatigue but also by improper posture during the action. Bending over is easier than squatting, and people naturally tend to choose the more comfortable strategy.
Rehabilitation medicine specialist Kiwon Kim from the SNU College of Medicine, who also contributed to the study, said: "Because the harmful effects of such comfortable but unsafe movements develop slowly, people do not recognize the risk in time, as in the case of disc degeneration."
The researchers developed a mechanism that blocks hip flexion when a person tries to bend over and unlocks it when they try to squat.
“We connected the upper back to the foot using a unique tendon structure consisting of vertical braking cables and a horizontal rubber band. When the hip is flexed and the knee is not bent, the hip flexion torque is transmitted to the foot through the braking cable, causing strong resistance to movement. However, if the knees spread laterally to squat, the angle between the tendons changes and the hip flexion torque switches to support from the rubber band”
The device was tested on ten people who used the suit for the first time. Nine of the ten participants changed their movement pattern closer to a squat form while wearing the exosuit. According to the researchers, this means an average improvement of 35% in participants' posture index. They also noted a 5.3% average reduction in participants' metabolic energy consumption.
The scientists are currently working on improving the MR Exosuit to test it in real working conditions. Trials are planned to begin soon. In 2022, the researchers intend to commercialize the device, but there is still work to be done. The suit's effectiveness was confirmed in the paper, but its long-term effects from wearing it were not.
“In the future, we plan to conduct experiments in various fields that require lifting posture training, such as industrial settings, gyms, and rehabilitation centers”
The engineers also plan further research to extend the principle of body-powered variable impedance to sports applications. Many whole-body sports, such as golf, swimming, and running, require proper movement training to improve safety and performance.
The research team plans to develop movement-training sportswear suitable for various sports, using soft materials such as cables and elastic bands. SNU research shows that artificial tendons, whose structure differs from human ones, can effectively help people by changing their movement patterns.
The existing version of the exosuit could be used to prevent improper lifting movements in patients with poor spinal conditions. The scientists expect their design to lead to changes in future wearable robotics research. They demonstrated that wearable devices do not need to imitate the original anatomical structure of the human body.
