We consider the problem of robust estimation involving filtering and smoothing for nonlinear state space models which are disturbed by heavy-tailed impulsive noises. To deal with heavy-tailed noises and improve the robustness of the traditional nonlinear Gaussian Kalman filter and smoother, we propose in this work a general framework of robust filtering and smoothing, which adopts a new maximum correntropy criterion to replace the minimum mean square error for state estimation. To facilitate understanding, we present our robust framework in conjunction with the cubature Kalman filter and smoother. A half-quadratic optimization method is utilized to solve the formulated robust estimation problems, which leads to a new maximum correntropy derivative-free robust Kalman filter and smoother. Simulation results show that the proposed methods achieve a substantial performance improvement over the conventional and existing robust ones with slight computational time increase.
IntroductionIn recent years, estimation problems involving filtering and smoothing based on dynamic state space models (SSMs) have received significant attentions. These problems are frequently encountered in many areas, such as target tracking, fault detection and diagnosis, parameter estimation, navigation, and many others. The celebrated Kalman filter (KF) [1] offers optimal estimation with the minimum mean square error (MMSE) for a linear SSM when both the process and measurement noises are Gaussian. Nevertheless, most applications in practice inherently have nonlinear SSMs, for which an optimal nonlinear filter or smoother is typically intractable. Several sub-optimal solutions were proposed for nonlinear SSMs, including the extended KF [2], unscented KF [3], cubature Kalman filter (CKF) [4], and others. Some interesting relations among these solutions can be found in [5,6]. Meanwhile, for smoothing, the Rauch-Tung-Striebel (RTS) smoother was introduced in [7] for linear Gaussian SSMs. A general framework of Gaussian optimal smoothing for nonlinear SSMs was proposed in [8], following which several sub-optimal nonlinear RTS smoothers were developed, such as the extended RTS smoother, unscented RTS smoother, cubature Kalman smoother (CKS), and others.Although the aforementioned filtering and smoothing methods in general perform well under the Gaussian assumption, they can potentially break down in the presence of heavy-tailed non-Gaussian noises, which may appear in either the process procedure or measurement procedure. This happens in, for instance, tracking a maneuvering target with outliers in observations [9]. A primary reason behind the degradation is that the traditional KF/RTS and their sub-optimal extensions were derived from the MMSE criterion, and the resulting estimates are sensitive to heavy-tailed noises [10]. * H. Wang is with the Persistent efforts have been devoted to tackling heavy-tailed noises in order to obtain more robust state estimates. Multiple models based techniques and sequential Monte Carlo sampling methods can be used ...