动态称重系统的建模及其参数估计

Model establishment and parameter identification for dynamic weighing system

阐述了为了兼顾动态称重系统的快速性和精度,将动态称重作为一个基于最小二乘法的参数估计和预测问题来处理,即从建立数学模型和信号处理算法方面加以解决。然后,将动态称重系统等效为二阶系统,分析得出了系统为时变非线性系统,推导出了系统的动态数学模型,并且,根据系统模型,将问题转化为参数辨识问题。辨识算法上,采用了基于Householder变换的自适应最小二乘法,其具有抗方程病态性好、稳定性好、估计精度高、计算量小、跟踪性好等优点。试验结果证明:所提出方法是可行的,达到了试验提出的技术要求,测量相对误差小于0.25%FS,系统在全量程范围内的准确度不低于0.25%。在提高称重速度的同时,也保证了系统的测量准确性,对于此类系统的实用化开发具有很好的参考价值。

In order to consider the speed and precision simultaneously in dynamic weighing system, the problem of dynamic weighing is resolved through parameter identification based on least square method and forecast method. The dynamic weighing system is equivalent to two orders system that is non-linearity time variable system, dynamic mathematic model is established by analysis. According to the system model, parameter identification method of adaptive least square based on Householder transformation is adopted. The Householder transformations have some advantages, for example, anti ill function, higher stability, higher precision, fewer calculation amount and good trace ability. The method adopted is feasible by prove of experiment result. Through the method, the technology requests are achieved, the relative error of measurement is less than 0.25 % FS and the accuracy in the full scale is no less than 0.25 % ; Not only the weighing speed but also precision are achieved. The method have the reference value for the practicality development of the similar weighing system to a great extent.