Glaister Brian C, Schoen Jason A, Orendurff Michael S, Klute Glenn K
Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA.
J Biomech Eng. 2009 Mar;131(3):034501. doi: 10.1115/1.3005153.
In order to protect sensitive residual limb soft tissues, lower limb prostheses need to control torsional loads during gait. To assist with the design of a torsional prosthesis, this paper used simple mechanical elements to model the behavior of the human ankle in the transverse plane during straight walking. Motion capture data were collected from ten able-bodied subjects walking straight ahead at self-selected walking speeds. Gait cycle data were separated into four distinct states, and passive torsional springs and dampers were chosen to model the behavior in each state. Since prosthetic design is facilitated by simplicity, it was desirable to investigate if elastic behavior could account for the physiological ankle moment and include viscous behavior only if necessary to account for the inadequacies of the spring model. In all four states, a springlike behavior was able to account for most of the physiological ankle moments, rendering the use of a damper unnecessary. In State 1, a quadratic torsional spring was chosen to model the behavior, while linear torsional springs were chosen for States 2-4. A prosthetic system that actively changes stiffness could be able to replicate the physiological behavior of the human ankle in the transverse plane. The results of this study will contribute to the mechanical design and control of a biomimetic torsional prosthesis for lower limb amputees.
为了保护敏感的残肢软组织,下肢假肢需要在步态过程中控制扭转负荷。为了辅助扭转假肢的设计,本文使用简单的机械元件对正常人在直线行走时踝关节在横向平面内的行为进行建模。从十名身体健全的受试者以自行选择的行走速度向前直线行走时收集运动捕捉数据。步态周期数据被分为四个不同的状态,并选择被动扭转弹簧和阻尼器来模拟每个状态下的行为。由于简化有助于假肢设计,因此有必要研究弹性行为是否能够解释生理踝关节力矩,并且仅在必要时纳入粘性行为以解释弹簧模型的不足。在所有四种状态下,类似弹簧的行为能够解释大部分生理踝关节力矩,因此无需使用阻尼器。在状态1中,选择二次扭转弹簧来模拟行为,而在状态2至4中选择线性扭转弹簧。一种能够主动改变刚度的假肢系统或许能够复制正常人踝关节在横向平面内的生理行为。本研究结果将有助于下肢截肢者仿生扭转假肢的机械设计与控制。