Abstract In this paper, a passive lower limb exoskeleton with hip and knee joints is proposed for walking assistance. The exoskeleton is designed with built-in spring mechanisms for gravity compensation of the human leg. A pair of mating gears is used to convert the tension force from the built-in springs into balancing torques at the hip and knee joints in order to overcome the influence of gravity. With the novel design, the exoskeleton has a compact layout with small protrusion, which improves its user acceptance and safety. In this paper, the working principle of the design for gravity compensation is described. A model is developed to analyze the effects of the design parameters. Simulations are conducted and the results show that the average absolute driving torque was reduced by 79.0% at the hip joint and 66.4% at the knee joint, with the use of this exoskeleton. Parametric study shows that lower gait speed, lower stiffness with larger pretension of the springs contribute to the maintenance of balance. A prototype of the leg exoskeleton was fabricated, and preliminary tests on healthy subjects verified usability of the exoskeleton.

中文翻译：

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一种重力补偿辅助步行的被动下肢外骨骼设计

摘要 在本文中，提出了一种具有髋关节和膝关节的被动下肢外骨骼用于辅助步行。外骨骼设计有内置弹簧机构，用于人体腿部的重力补偿。一对配对齿轮用于将内置弹簧的张力转换为髋关节和膝关节的平衡扭矩，以克服重力的影响。外骨骼设计新颖，布局紧凑，突出小，提高了用户的接受度和安全性。本文介绍了重力补偿设计的工作原理。开发了一个模型来分析设计参数的影响。进行了模拟，结果表明，髋关节的平均绝对驱动扭矩降低了 79.0%，膝关节的平均绝对驱动扭矩降低了 66.4%，使用这种外骨骼。参数研究表明，较低的步态速度、较低的刚度和较大的弹簧预紧力有助于保持平衡。制造了腿部外骨骼的原型，并对健康受试者进行了初步测试，验证了外骨骼的可用性。