单侧肌力减弱导致的步态不对称及踝部辅助改善：基于强化学习的仿真研究
Gait Asymmetry from Unilateral Weakness and Improvement With Ankle Assistance: a Reinforcement Learning based Simulation Study
AI总结：
本研究通过强化学习仿真框架，探讨单侧肌力减弱对步态对称性的影响，并验证踝关节外骨骼辅助改善步态对称性的效果。
摘要：
单侧肌肉无力常常导致步态不对称，破坏肢体间的协调性和支撑时间。本研究提出一个基于强化学习（RL）的肌肉骨骼仿真框架，旨在（1）量化渐进性单侧肌肉无力对步态对称性的影响，（2）评估在受损条件下踝关节外骨骼辅助是否能改善步态对称性。总体目标是建立一个基于仿真的学习工作流程，以支持在患者实验之前进行早期控制器开发。通过将右侧腿部肌肉强度降至基线的75%、50%和25%来诱导不对称步态。步态不对称性通过离地时间、峰值接触力和关节层面的对称性指标进行量化。随着无力程度的增加，时间性和运动学不对称性逐渐增大，最显著的表现是在踝关节。踝关节活动范围对称性从100%强度时的近对称行为（对称指数，SI=+6.4%；相关性r=0.974）降到了25%强度时的严重不对称（SI=-47.1%，r=0.889），同时负载向未受损侧转移。在50%强度时，踝关节外骨骼辅助相对于未辅助的受损条件改善了运动学对称性，将踝关节SI的幅度从25.8%降至18.5%，并将踝关节相关性从r=0.948提高到0.966，尽管峰值加载仍偏向未受损侧。总体而言，该框架支持对损伤严重程度和辅助策略的受控评估，并为未来的人体实验验证提供了基础。
英文摘要：
Unilateral muscle weakness often leads to asymmetric gait, disrupting interlimb coordination and stance timing. This study presents a reinforcement learning (RL) based musculoskeletal simulation framework to (1) quantify how progressive unilateral muscle weakness affects gait symmetry and (2) evaluate whether ankle exoskeleton assistance can improve gait symmetry under impaired conditions. The overarching goal is to establish a simulation- and learning-based workflow that supports early controller development prior to patient experiments. Asymmetric gait was induced by reducing right-leg muscle strength to 75%, 50%, and 25% of baseline. Gait asymmetry was quantified using toe-off timing, peak contact forces, and joint-level symmetry metrics. Increasing weakness produced progressively larger temporal and kinematic asymmetry, most pronounced at the ankle. Ankle range of motion symmetry degraded from near-symmetric behavior at 100% strength (symmetry index, SI = +6.4%; correlation r=0.974) to severe asymmetry at 25% strength (SI = -47.1%, r=0.889), accompanied by a load shift toward the unimpaired limb. At 50% strength, ankle exoskeleton assistance improved kinematic symmetry relative to the unassisted impaired condition, reducing the magnitude of ankle SI from 25.8% to 18.5% and increasing ankle correlation from r=0.948 to 0.966, although peak loading remained biased toward the unimpaired side. Overall, this framework supports controlled evaluation of impairment severity and assistive strategies, and provides a basis for future validation in human experiments.
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