直线超声电机非线性模型辨识

针对直线超声电机具有很强的非线性，理论建模困难，提出采用辨识方法建模. 首先分析了直线超声电机在不同驱动条件下的阶跃响应，提出将直线超声电机速度模型简化为带纯延迟的一阶惯性系统，驱动频率和相位差对电机动态参数的影响转化为所建模型时间常数、系统增益和延时间参数的变化. 然后用最小二乘法辨识出模型参数与驱动频率和相位差之间的函数关系，建立了直线超声电机的调频、调相控制非线性模型，为直线超声电机高精度控制提供了模型依据. 最后，通过比较直线超声电机阶跃响应的实测值与仿真值，验证了所建模型的有效性.

Nonlinear Model Identification of Linear Ultrasonic Motor

Since the speed characteristic of linear ultrasonic motor (LUSM) has strongly nonlinear property, it is difficult to derive an accurately mathematic model in theory. This problem is tried to be solved and a modeling method by identification is proposed in this paper. Firstly, the step responses of LUSM in different driving conditions were analyzed. It is proposed here that the model of LUSM can be simplified as one-order inertial pure lagging systems. The idea is to transform the effect of the driving frequency and phase difference of two-phase driving voltages into the changes of the parameters in the proposed model, such as time constants, gains and delays. Secondly, these parameters were obtained by least-squares regression, and dynamic nonlinear models of LUSM for frequency-speed control and phase-difference-speed control were proposed, which provide model basis for high accuracy control of LUSM. Finally, the validity of the proposed method is confirmed by experimental results.