基于时频切片分解的时变系统参数识别

Modal Parameter Identification of Time-varying System Based on Time Frequency Slice Decomposition

系统参数识别分为时不变系统参数识别和时变系统参数识别两大研究方向,其中时不变系统参数识别的研究已趋于成熟,而时变系统参数识别的研究则仍然处于起步阶段。对于多自由度时变结构,提出一种基于时频切片分解的时变系统参数识别方法。该方法采集结构的振动位移响应,根据时频分解计算得到响应在整个时频段内的时频能量分布图;依据结构的时频分布特性,选择多个时频切片窗分解响应信号,再对分解出的信号分别进行逆变换计算完成时域上的信号重构;重构出来的信号对应于结构的各阶模态位移响应信号,利用Hilbert变换提取信号瞬时频率,从而识别出结构各阶频率。通过一个三自由度的弹簧阻尼质量仿真实验,验证了该方法具有良好的识别精度和工程实用价值。

System parameter identification can be divided into two research directions: time-invariant system parameter identification and time-varying system parameter identification.The research on time-invariant system parameter identification has become mature,while the research on time-varying system parameter identification is still in its infancy.For multi-degree-of-freedom time-varying structures,a method for parameter identification based on time frequency slice decomposition is proposed.The first step of this method is to collect the displacement response of the structure,and then obtain the time-frequency energy distribution of the response in the whole time-frequency band.According to the time-frequency distribution characteristics of the structure,multiple time-frequency window signals are sliced out,and the inverse transform of FSWT is performed to reconstruct the signals in time domain.The reconstructed signal corresponds to each order modal displacement response signal of the structure.The instantaneous frequency of the signal is extracted by Hilbert transform,and the modal frequencies of each order of the structure are identified.According to a simulation experiment of the three-degree-of-freedom mass spring damping system,the method is proved to have good identification accuracy and practical engineering value.