论文标题
关于双线性时域的识别和减少Loewner框架
On Bilinear Time Domain Identification and Reduction in the Loewner Framework
论文作者
论文摘要
Loewner框架 - (LF)与Volterra系列(VS)结合使用,提供了一种非侵入性近似方法,能够通过时间域测量值鉴定双线性模型。该方法使用谐波输入,为数据获取建立自然方法。对于具有VS表示的非线性问题的一般类别,增长的指数方法允许推导广义内核,即对称的广义频率响应函数 - (GFRFS)。此外,Volterra操作员的同质性决定了考虑多少核的准确性。对于弱非线性设置,仅需要少量内核才能获得良好的近似值。在这个方向上,提出的自适应方案能够改善计算非零内核的估计。傅立叶变换将这些测量值与派生的GFRF相关联,而LF与系统理论建立了联系。在线性情况下,LF通过在频域中插值来将所谓的S-参数与线性转移函数相关联。该方法的目的是通过时间域测量结果将识别扩展到双线性系统的情况,并近似其他一般的非线性系统(通过Carleman Bienearizarizarion方案)。通过识别使用LF的线性贡献,通过SVD实现大量降低。拟合的线性系统具有与原始线性系统相同的McMillan学位。然后,通过增强特殊的非线性结构来提高线性模型的性能。简而言之,我们直接从可能在时域模拟的潜在大型系统中学习了减少差异双线性模型。这是通过首先拟合线性模型来完成的,然后通过拟合相应的双线性操作员来完成。
The Loewner framework-(LF) in combination with Volterra series-(VS) offers a non-intrusive approximation method that is capable of identifying bilinear models from time-domain measurements. This method uses harmonic inputs which establish a natural way for data acquisition. For the general class of nonlinear problems with VS representation, the growing exponential approach allows the derivation of the generalized kernels, namely symmetric generalized frequency response functions - (GFRFs). In addition, the homogeneity of the Volterra operator determines the accuracy in terms of how many kernels are considered. For the weakly nonlinear setup, only a few kernels are needed to obtain a good approximation. In this direction, the proposed adaptive scheme is able to improve the estimations of the computationally non-zero kernels. The Fourier transform associates these measurements with the derived GFRFs and the LF makes the connection with system theory. In the linear case, the LF associates the so-called S-parameters with the linear transfer function by interpolating in the frequency domain. The goal of the proposed method is to extend identification to the case of bilinear systems from time-domain measurements and to approximate other general nonlinear systems (by means of the Carleman bilinearizarion scheme). By identifying the linear contribution with the LF, a considerable reduction is achieved by means of the SVD. The fitted linear system has the same McMillan degree as the original linear system. Then, the performance of the linear model is improved by augmenting a special nonlinear structure. In a nutshell, we learn reduced-dimension bilinear models directly from a potentially large-scale system that is simulated in the time domain. This is done by fitting first a linear model, and afterwards, by fitting the corresponding bilinear operator.