基于机构运动学分析的人体下肢几何参数提取

Extraction of the Geometric Parameters of Human Low Limbs Based on Kinematics Analysis of Mechanism

由关节中心(轴)位置所确定的下肢几何参数是步态运动测量与分析的关键参数.已有的基于三维运动捕捉系统的步态运动测量应用中,人工干预因素较多,存在一定的主观性,从而对步态运动的测量信度产生显著的不利影响.针对这一问题,在对下肢环节和关节进行合理机构学简化的基础上,建立人体下肢多刚体运动学模型;通过下肢机构运动学分析,改进标志点设置方案;通过构造下肢运动的约束方程,充分利用大量的采样数据,推导了关节位置、模型几何参数的拟合算法.并通过试验验证测量方案及算法的有效性.

The geometric parameters of the lower limbs determined by the location of the joint centers(or axes) are the key parameters for gait kinematic measurement and analysis. The existing methods for gait motion measurement based on 3D motion capture instrument need much manual intervention. As a result, these methods have a certain degree of subjectivity, and the measurement accuracy and repeatability are impaired severely. Aim at this problem, the multi-body kinematics model of human lower limb is established based on reasonable simplifications to the body segments and joints of lower limbs. Through kinematic analysis, the configuration scheme of marker set is improved. By constructing the constraint equations of lower limb motion and making full use of a large amount of sample data, an algorithm for joint centers, geometric parameters of the model, and gait kinematics is established. The feasibility of the algorithm and the gait kinematics measurement method is verified by experiment.