In this paper, a semi-active exoskeleton used to reduce the muscle fatigue of the lower limb was designed and evaluated. Background: The advantages and disadvantages of assistive exoskeletons developed for industrial purposes were introduced. Simulation: The process of squatting was simulated in the AnyBody.7.1 software, the result showed that muscle activity of the gluteus maximus, rectus femoris, vastus medialis, vastus lateralis, vastus intermedius and erector spinae increased with increasing of knee flexion angle. Design: The exoskeleton was designed with three working modes: rigid-support mode, elastic-support mode and follow mode. Rigid-support mode was suitable for scenes where the squatting posture is stable, while elastic-support mode was beneficial for working environments where the height of squatting varied frequently. The working environments were identified intelligently based on the EMGs of the gluteus maximus and quadriceps, and the motor was controlled to switch the working mode between rigid-support mode and elastic-support mode. In follow mode, the exoskeleton moves freely with users without interfering with activities such as walking, ascending and descending stairs. Experiments: Three sets of experiments were conducted to evaluate the effect of exoskeleton. Experiment one was conducted to measure the surface electromyography signal (EMGs) , the root mean square of EMG amplitude of soleus, vastus lateralis, vastus medialis, gastrocnemius, vastus intermedius, rectus femoris, gluteus maximus and erector spinae were reduced by 98.5%, 97.89%, 80.09%, 77.27%, 96.73%, 94.17%, 70.71% and 36.32% respectively with the assistance of the exoskeleton. The purpose of experiment two was to measure the plantar pressure. With exoskeleton, the percentage of weight through subject's feet was reduced by 63.94%, 64.52% and 65.61% respectively at 0, 60 and 120 degrees of knee flexion angle. Experiment three was purposed to measure the metabolic cost at a speed of 4km/h and 5km/h with and without exoskeleton. experiment results show that the average additional metabolic cost introduced by exoskeleton was 2.525% and 2.85%. It indicated that the exoskeleton would not interfere with the movement of the wearer seriously in follow mode. Conclusion: The exoskeleton not only effectively reduced muscle fatigue, but also avoided interfering with the free movement of the wearer.

中文翻译：

---

基于肌电图的半主动外骨骼可减少蹲时的肌肉疲劳

在本文中，设计并评估了一种用于减轻下肢肌肉疲劳的半主动外骨骼。背景：介绍了为工业目的开发的辅助外骨骼的优缺点。模拟：在AnyBody.7.1软件中模拟了蹲下过程，结果显示，随着膝关节屈曲角度的增加，臀大肌，股直肌，股内侧肌，股外侧肌，中间股肌和竖脊肌的肌肉活动增加。设计：外骨骼设计有三种工作模式：刚性支撑模式，弹性支撑模式和跟随模式。刚性支撑模式适用于蹲姿稳定的场景，而弹性支撑模式适用于蹲姿高度频繁变化的工作环境。根据臀大肌和股四头肌的肌电图，智能地识别工作环境，并控制电动机以在刚性支撑模式和弹性支撑模式之间切换工作模式。在跟随模式下，外骨骼可以与用户自由移动，而不会干扰步行，上升和下降楼梯等活动。实验：进行三组实验以评估外骨骼的作用。实验一用于测量表面肌电信号（EMGs），比目鱼肌，外侧外侧肌，内侧内侧肌，腓肠肌，中间内侧肌，股直肌，臀大肌和竖脊肌的EMG振幅的均方根减小了98.5％，97.89。在外骨骼的帮助下，分别为％，80.09％，77.27％，96.73％，94.17％，70.71％和36.32％。实验二的目的是测量足底压力。在膝关节屈曲角度为0度，60度和120度时，使用外骨骼时，通过受试者脚部的重量百分比分别减少了63.94％，64.52％和65.61％。实验三的目的是在有和没有外骨骼的情况下以4km / h和5km / h的速度测量代谢成本。实验结果表明，外骨骼引入的平均额外代谢成本为2.525％和2.85％。这表明在跟随模式下，外骨骼不会严重干扰穿戴者的运动。结论：外骨骼不仅可以有效减轻肌肉疲劳，而且可以避免干扰佩戴者的自由运动。在0、60和120度的膝盖屈曲角度下，双脚分别减少了63.94％，64.52％和65.61％。实验三的目的是在有和没有外骨骼的情况下以4km / h和5km / h的速度测量代谢成本。实验结果表明，外骨骼引入的平均额外代谢成本为2.525％和2.85％。这表明在跟随模式下，外骨骼不会严重干扰穿戴者的运动。结论：外骨骼不仅可以有效减轻肌肉疲劳，而且可以避免干扰佩戴者的自由运动。在0、60和120度的膝盖屈曲角度下，双脚分别减少了63.94％，64.52％和65.61％。实验三的目的是在有和没有外骨骼的情况下以4km / h和5km / h的速度测量代谢成本。实验结果表明，外骨骼引入的平均额外代谢成本为2.525％和2.85％。这表明在跟随模式下，外骨骼不会严重干扰穿戴者的运动。结论：外骨骼不仅可以有效减轻肌肉疲劳，而且可以避免干扰佩戴者的自由运动。实验结果表明，外骨骼引入的平均额外代谢成本为2.525％和2.85％。这表明在跟随模式下，外骨骼不会严重干扰穿戴者的运动。结论：外骨骼不仅可以有效减轻肌肉疲劳，而且可以避免干扰佩戴者的自由运动。实验结果表明，外骨骼引入的平均额外代谢成本为2.525％和2.85％。这表明在跟随模式下，外骨骼不会严重干扰穿戴者的运动。结论：外骨骼不仅可以有效减轻肌肉疲劳，而且可以避免干扰佩戴者的自由运动。