Improving Sit/Stand Loading Symmetry and Timing Through Unified Variable Impedance Control of a Powered Knee-Ankle Prosthesis
Improving Sit/Stand Loading Symmetry and Timing Through Unified Variable Impedance Control of a Powered Knee-Ankle Prosthesis
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DOI：
10.1109/tnsre.2023.3320692
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发表时间：
2023-01-01
影响因子：
4.9
通讯作者：
Gregg，Robert D.
中科院分区：
文献类型：
--
作者：
Welker，Cara Gonzalez;Best，T. Kevin;Gregg，Robert D.
使用被动假肢的人通常严重依赖他们的生物肢体来完成坐着和站立的任务，导致完成时间变慢，骨关节炎和腰痛的发病率增加。动力假肢可以解决这些挑战，但其控制方法将坐立转换分为离散阶段，限制了用户在运动中的同步，并且需要长时间的手动调整时间。本文扩展了我们的初步工作，使用基于大腿的相位变量来参数化优化的数据驱动的阻抗参数轨迹，用于坐姿、站立和行走，只有两种分类模式。我们通过一个与膝盖速度相关的缩放项来解耦站-坐和坐-站平衡角度，与之前的结果相比，将模型拟合误差减少了大约一半。然后，我们用三个膝盖以上截肢的人进行坐姿和站立转换到三种不同的椅子高度来实验验证控制器。我们的研究表明，在动力膝踝假体上实施的控制器产生了仿生关节力学，与参与者的被动假体相比，显著减少了坐/站负载的不对称性和完成5倍坐-站任务的时间。与先前开发的步行控制器的集成还允许在不同的椅子高度之间进行坐/走转换。控制器的仿生辅助可以减少由于被动假肢不足而导致的对生物肢体的过度依赖，帮助改善膝盖以上截肢者的活动能力。
Individuals using passive prostheses typically rely heavily on their biological limb to complete sitting and standing tasks, leading to slower completion times and increased rates of osteoarthritis and lower back pain. Powered prostheses can address these challenges, but have control methods that divide sit-stand transitions into discrete phases, limiting user synchronization across the motion and requiring long manual tuning times. This paper extends our preliminary work using a thigh-based phase variable to parameterize optimized data-driven impedance parameter trajectories for sitting, standing, and walking, with only two classification modes. We decouple the stand-to-sit and sit-to-stand equilibrium angles through a knee velocity-dependent scaling term, reducing the model fitting error by approximately half compared to our previous results. We then experimentally validate the controller with three individuals with above-knee amputation performing sitting and standing transitions to/from three different chair heights. We show that our controller implemented on a powered knee-ankle prosthesis produced biomimetic joint mechanics, resulting in significantly reduced sit/stand loading asymmetry and time to complete a 5x sit-to-stand task compared to participants’ passive prostheses. Integration with a previously developed walking controller also allowed sit/walk transitions between different chair heights. The controller’s biomimetic assistance may reduce the overreliance on the biological limb caused by inadequate passive prostheses, helping improve mobility for people with above-knee amputations.