欠驱动异构式下肢康复机器人动力学分析及参数优化

Dynamic analysis and parameter optimization of under-actuated heterogeneous lower limb rehabilitation robot

针对现有外骨骼机器人人机自由度不匹配和关节对中性差的问题,提出欠驱动下肢康复机器人.欠驱动机器人只有4个直线驱动,驱动的直线运动通过推杆和人机连接机构转化为人下肢在矢状面内的屈伸运动,带动人体进行步态康复训练.建立机器人系统的人机耦合模型,进行模型的动力学分析,对人机耦合模型中影响动力学结果的参数进行分析,建立驱动力与肢体推动力之间的关系模型,并以推力系数最大为目标进行参数分析与优化,得到最佳的结构参数.根据优化后的结构参数搭建康复机器人实验系统,对髋、膝关节驱动力与角度进行对比.实验结果表明最大髋关节角度误差为2.9°,最大膝关节角度误差为6.4°,最大误差均约为9%,验证了动力学模型和参数优化结果的正确性.

An under-actuated lower limb rehabilitation robot was proposed aiming at the problems of humanmachine DOFS mismatch and poor joint neutrality of existing exoskeletons robots.The under-actuated robot system only has four linear drives.The linear motion driven by the robot is transformed into the flexion and extension of lower limbs in the sagittal plane through connecting rod and human-machine connection mechanism.Humanmachine coupling model was established for robot systems,and then dynamics analysis was carried out.The parameters in the human-machine coupling model that affect dynamic results were analyzed,a method to analyze the relationship between driving force and limb driving force was proposed,then the parameters with the maximum thrust coefficient as the target were analyzed and optimized,and the best structural parameters were obtained.Finally,the rehabilitation robot system was established based on the optimized structural parameters.The driving force and the angle of hip and knee joints were compared.Experimental results showed that the maximum error of the hip joint angle was 2.9°,the maximum angle error of the knee joint was 6.4°,and the maximum errors were about 9%,which verified the correctness of the dynamic model and the parameter optimization results.