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GNSS/INS integrated solution has been extensively studied over the past decades. However, its performance relies heavily on environmental conditions and sensor costs. The GNSS positioning can obtain satisfactory performance in the open area. Unfortunately, its accuracy can be severely degraded in a highly urbanized area, due to the notorious multipath effects and none-line-of-sight (NLOS) receptions. As a result, excessive GNSS outliers occur, which causes a huge error in GNSS/INS integration. This paper proposes to apply a fish-eye camera to capture the sky view image to further classify the NLOS and line-of-sight (LOS) measurements. In addition, the raw INS and GNSS measurements are tightly integrated using a state-of-the-art probabilistic factor graph model. Instead of excluding the NLOS receptions, this paper makes use of both the NLOS and LOS measurements by treating them with different weightings. Experiments conducted in typical urban canyons of Hong Kong showed that the proposed method could effectively mitigate the effects of GNSS outliers, and an improved accuracy of GNSS/INS integration was obtained, when compared with the conventional GNSS/INS integration. [ABSTRACT FROM AUTHOR]

Accurate and globally referenced global navigation satellite system (GNSS) based vehicular positioning can be achieved in outlier-free open areas. However, the performance of GNSS can be significantly degraded by outlier measurements, such as multipath effects and non-line-of-sight (NLOS) receptions arising from signal reflections of buildings. Inspired by the advantage of batch historical data in resisting outlier measurements, in this paper, we propose a graduated non-convexity factor graph optimization (FGO-GNC) to improve the GNSS positioning performance, where the impact of GNSS outliers is mitigated by estimating the optimal weightings of GNSS measurements. Different from the existing local solutions, the proposed FGO-GNC employs the non-convex Geman McClure (GM) function to globally estimate the weightings of GNSS measurements via a coarse-to-fine relaxation. The effectiveness of the proposed method is verified through several challenging datasets collected in urban canyons of Hong Kong using automobile level and low-cost smartphone level GNSS receivers. [ABSTRACT FROM AUTHOR]

Rail-track detection is a core function for automated rail transit perception. However, existing methods cannot effectively detect the rail-tracks in a complex environment, especially in turnout scenarios. In this study, we propose a topology guided method to detect rail-tracks which includes the following four parts: Firstly, a neural network is used to obtain the pixels of the rail-lanes, and the geometric relationship between rail-lanes is mined by inverse perspective transformation. Secondly, the rail-lanes’ pixels are converted to rail-lanes’ key points and the topological relationship between the key points. Thirdly, the rail-lanes are reconnected through topological relationships between key points. Finally, the rail-track geometry features are used to match the rail-lanes. Experimental results show that the rail-track level F1 score of the proposed method reached 91.62%, which is state-of-the-art (SOTA) in this field. Furthermore, the proposed method has been tested and applied on the Hong Kong Metro Tsuen Wan Line. [ABSTRACT FROM AUTHOR]