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Open AccessArticle

Robust Outlier-Adaptive Filtering for Vision-Aided Inertial Navigation

by Kyuman Lee 1,*,† and Eric N. Johnson 2
School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Drive, Atlanta, GA 30313, USA
Faculty of Aerospace Engineering, The Pennsylvania State University, 229 Hammond Building, University Park, PA 16802, USA
Author to whom correspondence should be addressed.
Current address: 55 River Oaks Pl, San Jose, CA 95134, USA.
Sensors 2020, 20(7), 2036;
Received: 7 March 2020 / Revised: 28 March 2020 / Accepted: 1 April 2020 / Published: 4 April 2020
(This article belongs to the Special Issue UAV-Based Smart Sensor Systems and Applications)
With the advent of unmanned aerial vehicles (UAVs), a major area of interest in the research field of UAVs has been vision-aided inertial navigation systems (V-INS). In the front-end of V-INS, image processing extracts information about the surrounding environment and determines features or points of interest. With the extracted vision data and inertial measurement unit (IMU) dead reckoning, the most widely used algorithm for estimating vehicle and feature states in the back-end of V-INS is an extended Kalman filter (EKF). An important assumption of the EKF is Gaussian white noise. In fact, measurement outliers that arise in various realistic conditions are often non-Gaussian. A lack of compensation for unknown noise parameters often leads to a serious impact on the reliability and robustness of these navigation systems. To compensate for uncertainties of the outliers, we require modified versions of the estimator or the incorporation of other techniques into the filter. The main purpose of this paper is to develop accurate and robust V-INS for UAVs, in particular, those for situations pertaining to such unknown outliers. Feature correspondence in image processing front-end rejects vision outliers, and then a statistic test in filtering back-end detects the remaining outliers of the vision data. For frequent outliers occurrence, variational approximation for Bayesian inference derives a way to compute the optimal noise precision matrices of the measurement outliers. The overall process of outlier removal and adaptation is referred to here as “outlier-adaptive filtering”. Even though almost all approaches of V-INS remove outliers by some method, few researchers have treated outlier adaptation in V-INS in much detail. Here, results from flight datasets validate the improved accuracy of V-INS employing the proposed outlier-adaptive filtering framework. View Full-Text
Keywords: V-INS; UAV; EKF; IMU; camera vision; computer vision; image processing; outlier rejection; adaptive filtering; sensor fusion; navigation V-INS; UAV; EKF; IMU; camera vision; computer vision; image processing; outlier rejection; adaptive filtering; sensor fusion; navigation
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Lee, K.; Johnson, E.N. Robust Outlier-Adaptive Filtering for Vision-Aided Inertial Navigation. Sensors 2020, 20, 2036.

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