基于Hammerstein模型的挖掘臂伺服系统参数辨识

摘要

液压挖掘臂伺服系统是复杂非线性系统,针对线性模型难以准确反映系统动态的特性,采用包含静态非线性模块和动态线性模块的Hammerstein模型来描述该系统.Hammerstein模型中的线性模块采用离散自回归模型(ARX),非线性模块则采用分段多项式基函数.利用多频率正弦激励与角度输出信号,采用带遗忘因子的递推最小二乘法实现线性与非线性模块参数的解耦辨识.通过对比实验分析辨识所得Hammerstein模型与ARX模型,得Hammerstein模型误差比线性模型误差减小约77％,结论表明采用Hammerstein模型描述挖掘臂伺服系统是有效可行的.%According to the complex nonlinear properties of hydraulic excavator arm ' s servo system, a Hammerstein model which contains static nonlinearity and dynamic linearity was adopted to describe the system instead of linear model. The dynamic linear module was described by a discrete Auto-Regressive eXogeneous (ARX ) model, and the static nonlinearity module was described by a two-segment polynomial. The forgetting factor recursive least square method was applied to realize decomposition identification of the parameters for both linear and nonlinear module through multi-frequency sinusoidal input and angle output signal. The comparison experiments between the identified Hammerstein model and ARX model indicated that the error of Hammerstein model was reduced by 77% , the results demonstrated that Hammerstein model meets the need for describing the servo system of excavator arm.