This paper describes a semi-powered ankle prosthesis and corresponding unified controller that provides biomimetic behavior for level and sloped walking without requiring identification of ground slope or modulation of control parameters. The controller is based on the observation that healthy individuals maintain an invariant external quasi-stiffness (spring like behavior between the shank and ground) when walking on level and sloped terrain. Emulating an invariant external quasi-stiffness requires an ankle that can vary the set-point (i.e., equilibrium angle) of the ankle stiffness. A semi-powered ankle prosthesis that incorporates a novel constant-volume power-asymmetric actuator was developed to provide this behavior, and the unified controller was implemented on it. The device and unified controller were assessed on three subjects with transtibial amputations while walking on inclines, level ground, and declines. Experimental results suggest that the prosthesis and accompanying controller can provide a consistent external quasi-stiffness similar to healthy subjects across all tested ground slopes.

中文翻译：

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半电动踝关节假肢和统一控制器，用于水平和倾斜行走

本文介绍了一种半动力踝关节假体和相应的统一控制器，该控制器可提供水平和倾斜步行的仿生行为，而无需识别地面坡度或调节控制参数。该控制器基于以下观察结果：健康的个体在水平和倾斜的地形上行走时保持不变的外部准刚度（小腿和地面之间的弹簧状行为）。模拟不变的外部准刚度需要脚踝，该脚踝可以改变脚踝刚度的设定点（即平衡角）。开发了一种具有新型恒定体积动力非对称执行器的半动力踝关节假体，以提供这种功能，并在其上实现了统一控制器。对该设备和统一控制器进行了评估，对三名在胫骨，水平地面和下坡路行走时进行截肢的受试者进行了评估。实验结果表明，在所有测试的地面坡度上，假体和相应的控制器都可以提供与健康受试者相似的一致的外部准刚度。