下肢外骨骼人机耦合交互力特性分析

Characteristic Analysis on Human-Machine Interaction Force of Lower Limb Exoskeleton

目的提出一种基于虚拟肌肉的人机耦合动力学建模方法,对穿戴外骨骼步行过程的人机交互力及穿戴者肌骨系统的肌肉激活情况等特征进行量化分析。方法首先在穿戴外骨骼的步态实验中,利用人体动作捕捉系统和自行开发的力学监测装置,同步获取穿戴者步行动力学、肌电信号、外骨骼驱动状态及局部的法向人机交互力信息;然后,在肌骨系统建模环境中建立人机耦合模型,并以步态实验数据和外骨骼关节扭矩作为耦合模型的驱动信息,进行逆动力学计算;最后,对模型的仿真数据与实验测试结果进行对比,量化评估下肢外骨骼人机耦合模型的有效性。结果耦合模型逆动力学计算的法向交互力以及下肢肌肉激活情况与步态实验测量结果相比,在响应曲线趋势上均具有良好一致性,其中交互力结果具有高程度的相关性(r=0.931,P<0.01),均方根误差较小,下肢肌肉激活程度峰值误差均小于5%。结论本文提出的人机耦合模型可有效计算人与外骨骼交互力。该耦合模型的建立为以后外骨骼结构优化与控制算法的验证与迭代,以及外骨骼助行助力功效的性能评估提供理论依据。

Objective To propose a human-machine coupling dynamics modeling method based on virtual muscles,so as to quantitatively analyze the characteristics of human-computer interaction force and muscle activation of the musculoskeletal system.Methods First,in the gait experiment of wearing exoskeleton,the human motion capture system and self-developed mechanical monitoring device were used to obtain the wearer’s walking dynamics,electromyography(EMG)signals,exoskeleton drive status and local human-computer interaction information.The human-machine coupling model was established in modeling environment of the bone system,and the gait experiment data and the exoskeleton joint torques were used as driving information of the coupling model to perform inverse mechanical calculations.Finally,by adjusting strength and stiffness parameters of the virtual muscles,the real data of the model was compared with the experimental test result,to quantitatively evaluate effectiveness of the human-machine coupling model of the lower extremity exoskeleton.Results The normal interaction force calculated by inverse dynamics of the coupled model and the activation of lower limb muscles had a good consistency in response curve trend compared with measurement results of the gait experiment,and the interaction force results had a high degree of correlation(r=0.931,P<0.01),the root mean square error was small,and the peak error of lower limb muscle activation was lower than 5%.Conclusions The human-machine coupling model proposed in this study can effectively calculate the interaction force between human and exoskeleton.The establishment of the coupling model provides a theoretical basis for verification and iteration of the exoskeleton structure optimization and control algorithm,as well as performance evaluation on mobility assistance effects of the exoskeleton.