Stroke survivors are often left suffering from gait instability due to hemiparesis. This gait dysfunction can lead to higher fall rates and an overall decrease in quality of life. Though there are many post-stroke gait rehabilitation methods in use currently, none of them allow patients to regain complete functionality. Interlimb coordination is one of the main mechanisms of walking and is usually overlooked in most post-stroke gait rehabilitation protocols. This work attempts to help further understand the mechanism of interlimb coordination and how the brain is involved in it, studying the contralateral response to unilateral stiffness perturbations. A unique robotic device, the Variable Stiffness Treadmill (VST), is used in conjunction with a pre-established neuromuscular gait model to analyze for the first time the supraspinal control mechanisms involved in inter-leg coordination induced after unilateral perturbations. The attempt to explain the observed kinematic and muscular activation data via the gait model results in the identification of two control variables that seem to play an important role in gait stability and recovery after perturbations: the target angle of attack and target hip to ankle span. This is significant because these two parameters are directly related to longer stride length and larger foot clearance during swing phase. Both variables work toward correcting common issues with hemiparetic gait, such as a shorter stride and toe drag during swing phase of the paretic leg. The results of this work could aid in the design of future model-based stroke rehabilitation methods that would perturb the subject in a systematic way and allow targeted interventions with specific functional outcomes on gait. Additionally, this work-along with future studies-could assist in improving controllers for robust bipedal robots as well as our understanding of how the brain controls balance during perturbed walking.

中文翻译：

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基于模型的人类步态腿间协调的脊柱上机制分析：走向模型知情的机器人辅助康复


中风幸存者经常因偏瘫而出现步态不稳定。这种步态功能障碍会导致更高的跌倒率和生活质量的整体下降。尽管目前有许多中风后步态康复方法在使用，但没有一种能让患者恢复完整的功能。四肢间协调是行走的主要机制之一，在大多数中风后步态康复方案中通常被忽视。这项工作试图帮助进一步了解肢体间协调的机制以及大脑如何参与其中，研究对单侧刚度扰动的对侧反应。一种独特的机器人设备，可变刚度跑步机（VST），与预先建立的神经肌肉步态模型结合使用，首次分析单侧扰动后引起的腿间协调所涉及的脊柱上控制机制。通过步态模型解释观察到的运动学和肌肉激活数据的尝试导致了两个控制变量的识别，这两个控制变量似乎在扰动后的步态稳定性和恢复中发挥着重要作用：目标攻角和目标髋踝跨度。这很重要，因为这两个参数与摆动阶段较长的步幅和较大的脚间隙直接相关。这两个变量都致力于纠正偏瘫步态的常见问题，例如偏瘫腿摆动阶段的步幅较短和脚趾阻力。这项工作的结果可以帮助设计未来基于模型的中风康复方法，该方法将以系统的方式干扰受试者，并允许对步态进行具有特定功能结果的有针对性的干预。 此外，这项工作以及未来的研究可以帮助改进稳健的双足机器人的控制器，以及我们对大脑如何在扰动行走过程中控制平衡的理解。