考虑膝关节转动刚度的二段腿行走步态分析

为研究腿部构造对双足倒立摆行走步态的影响,提出了一种含膝关节的二段腿倒立摆模型,确定了腿部受到的反力和腿长的关系,建立了模型运动控制方程和仿真模型,采用庞加莱映射和牛顿迭代法求得了模型周期性行走步态结果,分析了机械能、冲击角、膝关节初始角度、膝关节转动刚度等模型参数对行走步态的影响.分析结果表明:含膝关节的二段腿初始刚度较大,随着变形的增大刚度逐渐减小,表明二段腿存在受力柔化特性；二段腿模型能够在一定参数范围内实现多种周期性步态,给定合适的参数组合,模型能够覆盖人体正常行走的频率区间.对比线弹簧模型,本文模型构造更接近于真实人体,模型参数物理意义明确,为模型的实验验证和参数标定打下了基础.

Gait analysis of two-segment leg considering knee joint rotational stiffness

To investigate the influence of the structure of legs on walking gait patterns of bipedal inverted pendulum, a bipedal model with two-segment legs was proposed. The relationship between the reaction force on the leg and the length of the leg was determined. Functions of motion and the simulation model of the proposed bipedal model were built. Periodic walking gait patterns were solved with Poincare return map and Newton-Raphson algorithm. Influences of model parameters including mechanical energy, attack angle, knee rest angle, and joint stiffness on gait patterns were analyzed. Analytical results show that the initial stiffness of the two-segment leg was large, while it gradually decreased with the increase of the deformation of the leg, indicating that the two-segment leg may soften with deformation. The proposed bipedal model could achieve various walking gait patterns in a certain range of parameters. It could also cover the range of the pacing rate of normal human walking, if the values of the parameters were well selected. Compared with models with linear spring legs, the proposed model was closer to the body structure of real human, and the physical meanings of its parameters were clearer, which lays foundation for experimental verification and parameters calibration of the model.