Adaptation of a smart walker for stroke individuals: a study on sEMG and accelerometer signals

Abstract Introduction: Stroke is a leading cause of neuromuscular system damages, and researchers have been studying and developing robotic devices to assist affected people. Depending on the damage extension, the gait of these people can be impaired, making devices, such as smart walkers, useful for rehabilitation. The goal of this work is to analyze changes in muscle patterns on the paretic limb during free and walker-assisted gaits in stroke individuals, through accelerometry and surface electromyography (sEMG). Methods The analyzed muscles were vastus medialis, biceps femoris, tibialis anterior and gastrocnemius medialis. The volunteers walked three times on a straight path in free gait and, further, three times again, but now using the smart walker, to help them with the movements. Then, the data from gait pattern and muscle signals collected by sEMG and accelerometers were analyzed and statistical analyses were applied. Results The accelerometry allowed gait phase identification (stance and swing), and sEMG provided information about muscle pattern variations, which were detected in vastus medialis (onset and offset; p = 0.022) and biceps femoris (offset; p = 0.025). Additionally, comparisons between free and walker-assisted gaits showed significant reduction in speed (from 0.45 to 0.30 m/s; p = 0.021) and longer stance phase (from 54.75 to 60.34%; p = 0.008). Conclusions Variations in muscle patterns were detected in vastus medialis and biceps femoris during the experiments, besides user speed reduction and longer stance phase when the walker-assisted gait is compared with the free gait.

引言：脑卒中（Stroke）是引发神经肌肉系统损伤的主要病因之一，学界长期致力于研发机器人设备以辅助卒中后受损患者。根据损伤范围的不同，此类患者的步态可出现异常，智能助行器（smart walker）等设备可有效辅助其康复训练。本研究旨在通过加速度测量法（accelerometry）与表面肌电图（surface electromyography, sEMG），分析卒中患者在自由步态与助行器辅助步态下，患侧肢体的肌肉模式变化情况。
方法：本次分析的受试肌肉包括股内侧肌、股二头肌、胫骨前肌与内侧腓肠肌。受试者先在直道上以自由步态行走三次，随后借助智能助行器完成三次直道行走。研究人员对采集得到的步态模式数据、表面肌电信号与加速度计数据进行分析，并开展统计学检验。
结果：加速度测量法可实现步态时相识别（站立相与摆动相）；表面肌电图可获取肌肉模式变化信息，该变化在股内侧肌（激活起始与终止时刻；p=0.022）与股二头肌（激活终止时刻；p=0.025）中被检测到。此外，自由步态与助行器辅助步态的对比结果显示，受试者步行速度显著下降（从0.45 m/s降至0.30 m/s；p=0.021），站立相时长显著延长（从54.75%提升至60.34%；p=0.008）。
结论：本实验中，研究人员在股内侧肌与股二头肌中检测到肌肉模式变化；相较于自由步态，助行器辅助步态下受试者的步行速度降低、站立相时长显著延长。