基于系统辨识的颤摆质量模型在跳深动作中的动力学仿真

The Kinetics Simulation of Drop Jump with Wobbling Mass Model Based on System Identification

目的:利用系统辨识与优化解算跳深动作颤摆质量模型中力学元件的参数,并结合计算机仿真探讨模型在冲击性动作动力学仿真中的有效性和实用性。方法:将人体简化为1自由度的颤摆质量模型,导出相应的状态方程,将实验所得人体多刚体模型质心于垂直方向上的运动学数据作为输入量,地面垂直反作用力作为比较量,采用n4 sid子空间系统辨识方法并结合约束优化方法求解出模型力学元件参数估值,回代模型仿真计算输出跳深动作过程中的垂直地面反作用力。结果:辨识与各种初始条件下仿真所得到的地面力值与实测地面力值的拟合度均可达到80%左右;随跳深高度的增加,模型中力学元件的刚度k与阻尼c的值也呈增大趋势;运动学解析数据的精度对拟合度有较大的影响。结论:基于系统辨识的颤摆质量模型可有效反映人体在受到冲击时整体粘弹性的响应表现,而通过个体实验确定模型内参数的方法,也使得模型在应用时更具针对性和灵活性。

Using system identification and parameters of mechanics component in wobbling mass model of optimized resolution of drop jump, the present research aims to investigate the effectiveness and validity of the model in kinetics simulation of impact strength. Methods： Simplify the human body to a wobbling mass model with one degree freedom, use as input quantity the kinematic data of the barycenter of the model of human multi-rigid body along pure vertical line and use the ground vertical reacting force as comparative quantity, and use the n4sid sub-space system identification methods to obtain the generalized state equation. Find out the estimated values ofmechanical component parameters of the model by way of the constrained optimization methods and output the vertical ground force in drop jump process by way of inverse model simulation calculation. Results： The fitting degree between the simulated vertical ground force and the actual vertical ground force is about 80%. The values of the rigidity k and the damping c of the mechanical components in the model get larger with the increase of drop height. The precision of the kinetics analysis data has a greater influence on the fitting degree. Conclusions： the wobbling mass model based on system identification can effectively reveal the whole body＇ s viscoelastic characteristics when it is under impact, while the method of identifying parameters within the model through individual experiment brings more directions and flexibility to the model.