Mesh-free adjoint methods for nonlinear filters

Fred Daum

doi:10.1117/12.610672

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14 September 2005 Mesh-free adjoint methods for nonlinear filters

Fred Daum

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Proceedings Volume 5913, Signal and Data Processing of Small Targets 2005; 59130D (2005) https://doi.org/10.1117/12.610672
Event: Optics and Photonics 2005, 2005, San Diego, California, United States

Abstract

We apply a new industrial strength numerical approximation, called the "mesh-free adjoint method", to solve the nonlinear filtering problem. This algorithm exploits the smoothness of the problem, unlike particle filters, and hence we expect that mesh-free adjoints are superior to particle filters for many practical applications. The nonlinear filter problem is equivalent to solving the Fokker-Planck equation in real time. The key idea is to use a good adaptive non-uniform quantization of state space to approximate the solution of the Fokker-Planck equation. In particular, the adjoint method computes the location of the nodes in state space to minimize errors in the final answer. This use of an adjoint is analogous to optimal control algorithms, but it is more interesting. The adjoint method is also analogous to importance sampling in particle filters, but it is better for four reasons: (1) it exploits the smoothness of the problem; (2) it explicitly minimizes the errors in the relevant functional; (3) it explicitly models the dynamics in state space; and (4) it can be used to compute a corrected value for the desired functional using the residuals. We will attempt to make this paper accessible to normal engineers who do not have PDEs for breakfast.

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Fred Daum "Mesh-free adjoint methods for nonlinear filters", Proc. SPIE 5913, Signal and Data Processing of Small Targets 2005, 59130D (14 September 2005); https://doi.org/10.1117/12.610672

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