Nudged Particle Filter with Optimal Resampling Applied to the Duffing Oscillator
Ryne Beeson, Uwe Hanebeck
TL;DR
This work tackles the challenge of filtering chaotic dynamical systems with separatrix structures, where standard particle filters struggle due to degeneracy and multi-modal posteriors. It introduces the intermediate resampling nudged particle filter (IRnPF), which couples a control-based nudging toward the future observation with a deterministic resampling step that minimizes the modified Cramér-von Mises distance $D(\mu,\nu)$ to control weight variance. The method is demonstrated on the 2D stochastic Duffing oscillator, showing that IRnPF consistently outperforms both the standard PF and the original nudged PF at the same particle count, particularly across separatrix boundaries. The results suggest IRnPF offers a more robust and efficient filtering strategy for chaotic, sparsely observed systems and may extend to higher-dimensional problems.
Abstract
Efficiently solving the continuous-time signal and discrete-time observation filtering problem for chaotic dynamical systems presents unique challenges in that the advected distribution between observations may encounter a separatrix structure that results in the prior distribution being far from the observation or the distribution may become split into multiple disjoint components. In an attempt to sense and overcome these dynamical issues, as well as approximate a non-Gaussian distribution, a nudged particle filtering approach has been introduced. In the nudged particle filter method a control term is added, but has the potential drawback of degenerating the weights of the particles. To counter this issue, we introduce an intermediate resampling approach based on the modified Cramér-von Mises distance. The new method is applied to a challenging scenario of the non-chaotic, unforced nonlinear Duffing oscillator, which possesses a separatrix structure. Our results show that it consistently outperforms the standard particle filter with resampling and original nudged particle filter.
