摘要
目的研究足踝生物力学动态仿真实验台的控制问题，提出一套完整的多轴控制算法使实验台在模拟自由度、时间和精度、负荷重量、调试效率等指标上与国际同行相比具有竞争力。方法设计人体足踝步态实验台，通过5个伺服电机驱动的机构模拟步态的运动过程（5个自由度）。基于对整个步态过程中力加载的科学分析和合理简化，在Matlab中对此多自由度力加载的过程进行建模。提出运用PID迭代学习算法来控制力，并在Simulink中进行仿真分析。基于仿真的参数，在实际搭建的系统上验证该算法的有效性与可靠性。结果经过4～5次的迭代学习，实验台可以在5s时间内完成1个支撑相的模拟，3个方向的足底反力（Fz、Fy、Fx）都具有重复性和可控性，在50％的人体体重下Fz和Fy输出曲线与目标曲线的均方根误差分别收敛到20N和8N，小于模拟负载的10％。结论迭代学习控制方法可使足踝步态模拟实验台具有较强的力学模拟能力，提高了实验台的智能性，为后续进一步提高模拟速度和精度奠定良好的基础，其研制对尸体足踝生物力学实验具有重要意义。
Objective To study the control problem in dynamic foot biomechanical simulator and propose a com- plete multi-axis control algorithm which could be more competitive than that of current gait simulators in aspects as simulations in degree-of-freedom （ DOF）, velocity, precision, weight-bearing and trial efficiency. Methods A novel custom-made foot and ankle biomechanical simulator was developed to simulate both motion and force characteristics in a stance phase with .5 DOF. A model of the simulator was built in Matlab based on gait analysis and reasonable simplification. Iteration learning control （ILC） was proposed to control multi-axis forces and was verified in Simulink. Finally, the control strategy was validated in the simulation platform with a prosthetic foot. Results The novel simulator could complete the motion and force loading process within 5 seconds in one stance after 4-5 iterations. All 3D ground reaction forces （ F,, Fy and Fx） had high verified repeatability. The tracking curves of Fz and Fy with 50% of real body weight could converge to the target ones with root mean square （RMS） error of 20 N and 8 N using ILC, respectively, which was smaller than 10% of simulated loads. Conclusions The proposed control strategy greatly improved intelligence of the simulator and provided a good foundation to further improve the simulation speed and accuracy. The development of the simulator is of great significance to the cada- veric experiments on foot and ankle biomechanics.
出处
《医用生物力学》
EI
CAS
CSCD
北大核心
2014年第4期355-362,共8页
Journal of Medical Biomechanics
基金
国家自然科学基金资助项目(81071234)
关键词
步态模拟器
力控制
迭代学习
生物力学
Gait simulator
Force control
Iterative learning control（ILC）
Biomechanics
