This paper addresses the problem of nonlinear filtering, i.e., computing the conditional distribution of the state of a stochastic dynamical system given a history of noisy partial observations. The primary focus is on scenarios involving degenerate likelihoods or high-dimensional states, where traditional sequential importance resampling (SIR) particle filters face the weight degeneracy issue. Our proposed method builds on an optimal transport interpretation of nonlinear filtering, leading to a simulation-based and likelihood-free algorithm that estimates the Brenier optimal transport map from the current distribution of the state to the distribution at the next time step. Our formulation allows us to harness the approximation power of neural networks to model complex and multi-modal distributions and employ stochastic optimization algorithms to enhance scalability. Extensive numerical experiments are presented that compare our method to the SIR particle filter and the ensemble Kalman filter, demonstrating the superior performance of our method in terms of sample efficiency, high-dimensional scalability, and the ability to capture complex and multi-modal distributions.

基于最优输运解释的非线性滤波方法通过模拟和无似然算法估计从当前状态分布到下一个时间步的Brenier最优输运映射，利用神经网络建模复杂和多模态分布以及采用随机优化算法提高可伸缩性，通过广泛的数值实验与SIR粒子滤波器和集合卡尔曼滤波器进行比较，展示了我们方法在样本效率、高维可伸缩性和捕捉复杂和多模态分布等方面的优越性。

基于最优传输的高维非线性滤波