通过分两步识别慢流形,高效建模高维快慢系统动力学。
SINDy on slow manifolds
- 先拟合快变量与慢变量的代数关系,再构建流形约束下的动态模型。
- 库规模和条件数显著降低,实测在梁屈曲与机翼绕流中准确率提升。
- 适合复杂多尺度系统建模,尤其适用于数据驱动的物理机制发现。
稀疏非线性动力学识别(SINDy)是利用数据学习可解释动力系统模型的有效方法。然而,对于高维快慢耦合系统,其回归问题同时面临计算不可行与病态难题。理论上仅建模慢流形上的动力学可解决上述问题,但需引入高阶非线性项补偿截断的快变量,导致SINDy候选项库呈指数爆炸式增长。本文提出一种新SINDy变体,分两步实现:(i) 识别慢流形,即建立快变量关于慢变量的代数表达式;(ii) 在该流形上学习慢变量的动力学模型。关键在于,第(i)步所得方程被用于构造第(ii)步的流形感知函数库,仅包含必要高阶非线性项,而非所有低阶单项式。该定制化库为原库的稀疏子集,专用于特定问题。在突跳屈曲梁与NACA 0012机翼绕流的数值实验中,该方法显著降低条件数与库大小,实现了对慢流形上动力学的精确识别。
原文摘要 · Abstract (English)
The sparse identification of nonlinear dynamics (SINDy) has been established as an effective method to learn interpretable models of dynamical systems from data. However, for high-dimensional slow-fast dynamical systems, the regression problem becomes simultaneously computationally intractable and ill-conditioned. Although, in principle, modeling only the dynamics evolving on the underlying slow manifold addresses both of these challenges, the truncated fast variables have to be compensated by including higher-order nonlinearities as candidate terms for the model, leading to an explosive growth in the size of the SINDy library. In this work, we develop a SINDy variant that is able to robustly and efficiently identify slow-fast dynamics in two steps: (i) identify the slow manifold, that is, an algebraic equation for the fast variables as functions of the slow ones, and (ii) learn a model for the dynamics of the slow variables restricted to the manifold. Critically, the equation learned in (i) is leveraged to build a manifold-informed function library for (ii) that contains only essential higher-order nonlinearites as candidate terms. Rather than containing all monomials of up to a certain degree, the resulting custom library is a sparse subset of the latter that is tailored to the specific problem at hand. The approach is demonstrated on numerical examples of a snap-through buckling beam and the flow over a NACA 0012 airfoil. We find that our method significantly reduces both the condition number and the size of the SINDy library, thus enabling accurate identification of the dynamics on slow manifolds.
Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。