基于弹性形变摩擦力的光学天线伺服系统建模

Modeling of optical antenna servo system using elastic deformation friction torque

摘要:

目的：针对光学天线伺服系统非线性建模问题，提出了一种弹性形变摩擦力模型描述系统的非线性效应，并采用遗传算法实现模型参数辨识。方法：首先，给出了弹性形变摩擦力经验公式，将摩擦力描述为相对运动物体表面接触形变产生的弹性力，接触形变在相对运动过程中连续变化，消除了Stribeck模型零速度不连续性，且参数比LuGre模型少，无需求解微分方程，降低了模型辨识难度。然后，以模型输出速度与实测伺服电机输出速度误差平方和为评价函数，采用遗传算法实现了三种模型的参数辨识。结果：实验结果表明：在相同的遗传进化迭代次数下，弹性形变摩擦力模型精度比Stribeck模型提高2.3倍，比LuGre模型提高4.6倍。结论：验证了弹性形变摩擦力模型用于伺服系统非线性建模的可行性。

Abstract:

Objetive: In order to realize nonlinear model identification of optical antenna servo system, an elastic deformation friction model is proposed to describe the nonlinear effect of the system, and the genetic algorithm is used to identify model parameters. Method : First, the empirical formula of elastic deformation friction force is given, which considers that the friction force is originated by the elastic deformation of the asperities of the contacting surfaces. The contact behaves as a spring, and the contact deformation changes continuously during relative motion, eliminating the discontinuity at zero velocity of Stribeck model. Compared with the LuGre model, this model has fewer parameters and does not need to solve differential equations, which reduces the difficulty of parameter identification. Then, the parameter identification of the three models is realized by using the genetic algorithm with the square sum of the error between the model and the measured data of servo system as the evaluation function. Result: Experimental results indicate that: under the same genetic evolution process, the accuracy of the elastic deformation friction model is 2.3 times higher than that of the Stribeck model, and 4.6 times higher than that of the LuGre model. Conclusion: The results verify the feasibility of the elastic deformation friction model for nonlinear modeling of servo system.