变频率条件下Galfenol驱动器参数辨识方法研究

Parameters identifications of Galfenol actuator at variable frequencies

利用线性压磁方程和欧拉-伯努利方程建立了基于Galfenol(Fe-Ga合金)驱动器的动力学模型,在变频率条件下,驱动磁场存在扩散效应,直接影响模型对于驱动器动态特性的预测。为解决普通梯度算法无法收敛的问题,提出了一种基于遗传算法的动力学模型参数辨识方法,无需满足持续激励条件,可对变频率条件下驱动器的压磁系数和阻尼系数进行辨识。计算结果表明,辨识算法收敛性好,经过7次迭代以后即可寻找到最优值。同时进行了对比实验,结果显示驱动频率低于220Hz时模型参数变化较小,更高驱动频率时模型参数发生较大的变化。利用该方法可以在变频率条件下准确掌握驱动器结构参数的变化,为Galfenol驱动器磁路的设计与控制提供理论指导。

A dynamic model of Galfenol actuator is developed by using a linear piezomagnetic equation and the Euler-Bernoulli equation.The magnitude and the phase of the excitation field demonstrate the diffusion effect in the magnetic circuit due to the existence of the dynamic eddy current loss.The model prediction of the flexible beam can be directly affected by the influence of the eddy current loss.A genetic algorithm is proposed to identify the parameters of the model,for which the persistent excitation condition is not needed.The piezo-coefficient and the damping constant are identified at different dynamic frequencies.Simulation results show that the proposed method achieves good convergence performance that the optimal model parameters can be found after several iterations.Experimental results show that the variations of the model parameters are small when the exciting frequency was low(less than 220Hz).Larger variations happen when higher frequencies are applied.The changes of the model parameters according to the eddy current loss at different frequencies can be effectively described by the method,which can be used for design and control of the Galfenol flexible structure.