According to an implementation, a set of particles is provided for use in estimating a location of a state of a dynamic system. A local-mode seeking mechanism is applied to move one or more particles in the set of particles, and the number of particles in the set of particles is modified. The location of the state of the dynamic system is estimated using particles in the set of particles. Another implementation provides dynamic state estimation using a particle filter for which the particle locations are modified using a local-mode seeking algorithm based on a mean-shift analysis and for which the number of particles is adjusted using a Kullback-Leibler-distance sampling process. The mean-shift analysis may reduce degeneracy in the particles, and the sampling process may reduce the computational complexity of the particle filter. The implementation may be useful with non-linear and non-Gaussian systems.