The continual miniaturization of mass-market sensors built in mobile intelligent terminals has inspired the development of accurate and continuous navigation solution for portable devices. With the release of Global Navigation Satellite System (GNSS) observations from the Android Nougat system, smartphones can provide pseudorange, Doppler, and carrier phase observations of GNSS. However, it is still a challenge to achieve the seamless positioning of consumer applications, especially in environments where GNSS signals suffer from a low signal-to-noise ratio and severe multipath. This paper introduces a dedicated android smartphone application called Walker that integrates the GNSS navigation solution and MEMS (micro-electromechanical systems) sensors to enable continuous and precise pedestrian navigation. Firstly, we introduce the generation of GNSS and MEMS observations, in addition to the architecture of Walker application. Then the core algorithm in Walker is given, including the time-differenced carrier phase improved GNSS single-point positioning and the integration of GNSS and Pedestrian Dead Reckoning (PDR). Finally, the Walker application is tested and the observations of GNSS and MEMS are assessed. The static experiment shows that, with GNSS observations, the RMS (root mean square) values of east, north, and up positioning error are 0.49 m, 0.37 m, and 1.01 m, respectively. Furthermore, the kinematic experiment verifies that the proposed method is capable of obtaining accuracy within 1–3 m for smooth and continuous navigation.

Nowadays, the autonomous vehicle has undergone an impressive development, in which one of the most challenging tasks is to pursue high-precision and continuous navigation in complex scenarios. However, GNSS signals are very likely to be blocked and the inertial system suffers from error drift over time. To achieve centimeter-level positioning accuracy, a tightly-coupled model is built via fusing visual, GNSS, and INS measurements, based on a priori visual feature map. The visual map is first generated by a visual mobile surveying system, and the quality of the map is improved by outlier elimination and road lane tracking. This visual feature map consists of two layers that involve 3D coordinates of robust visual features and road lane markings, then two GNSS/INS/Vision fusion models are developed. The first one fuses visual 2D-3D feature matching, GNSS, and INS measurement. The proposed system is effective even when satellites are all out of lock. The second one fuses lane line constraints with GNSS, INS, and distance measurement indicator (DMI). In the experiment part, we show how a visual feature map is generated and refined, then, the performance of the positioning algorithm is evaluated. For the first fusion model, we achieve 10 cm RMS accuracy when only one feature point was matched and all GNSS signals are blocked for 20 minutes. For the other fusion model, the system maintained 10 cm RMS accuracy or even better when a few GNSS satellites are out of lock for 300 seconds.

In urban environments, positioning performance of global navigation satellite system (GNSS) degrades severely due to the harsh environment, which will be improved after fused with a strap-down inertial navigation system (SINS). However, owing to the error accumulation, the positioning ability of GNSS/SINS integration will also decrease significantly during frequent GNSS outages. To improve the positioning accuracy, we use stereo vision to enhance the performance of GNSS/SINS integration, where GNSS and stereo vision are loosely coupled and tightly coupled with SINS under the earth-centered earth-fixed (ECEF) frame, respectively. To evaluate the positioning performance of the multi-sensor fusion system, two in-field experiments were conducted to assess the contribution of stereo vision. The results show that with the support of stereo vision and SINS, GNSS accuracy can be considerably improved by 60%~80% in complex environments, which also outperforms the GNSS/SINS integration. Besides, detailed analyses in various urban environments further demonstrate that stereo vision can significantly improve the performance of GNSS/SINS integration when a long-term GNSS anomaly occurs, but it shows no improvement for a short-term GNSS anomaly.

High-precision continuous position and attitude determination are the critical modules of mobile mapping and autonomous driving. Research in the integration of global navigation satellite system (GNSS) and strapdown inertial navigation system (SINS) has greatly enhanced the accuracy and robustness of position and attitude in different scenes. However, the complexity and variability of the real scenes are still challenging for the existing models, parameters, strategies, and algorithms (MPSA). It is worth noting that high-quality datasets are key to accelerating the research and development of MPSA, which has been proved in the computer vision (CV) fields represented by the ImageNet dataset. Unfortunately, current public datasets either do not provide the raw observations of GNSS and inertial navigation units (IMU) or are not collected in abundant scenes and moving platforms. Therefore, a large-scale diverse GNSS/SINS dataset, named SmartPNT-POS, is presented. This dataset covers rich real-world environments, such as open-sky and complex urban, and multiple moving platforms, like aircraft, land vehicles, and ships. In addition, different types of IMUs, including those manufactured in Hexagon, iMAR Navigation GmbH, Honeywell, etc., are contained in SmartPNT-POS as well. Moreover, it provides ground truths in each group of data for users to analyze and evaluate their MPSA. Now the dataset is publicly available through Kaggle, a data science community, and the website to obtain the dataset is provided in the text. There have been thirty sets of data published on the website up to the present, and comprehensive analyses have been made in this contribution for the position and attitude determination results obtained by different processing modes. More data will be collected for different environments and applications, and published on the same website in the future.