A Continuous Positioning Algorithm Based on RTK and VI-SLAM With Smartphones

Abstract

The navigation technology has developed rapidly and immensely over the past few decades. Among the multiple navigation technologies, the representative and promising techniques are Real-time Kinematic (RTK) technique and Simultaneous Localization and Mapping (SLAM). RTK can provide realtime positioning results with high accuracy, while SLAM can not only locate the user but also construct a map of the new ambient. The first smartphone, the Xiaomi MI 8, equipped with the dual-frequency Global Navigation Satellite System (GNSS), hit the market in May 2018, providing valid carrier-phase measurements for RTK owe to the developer option of "Force full GNSS measurements." Nevertheless, RTK underperforms in urban areas as the buildings and trees can block the satellite signals. RTK cannot even provide positioning results when the GNSS outage happens. However, SLAM can effectively make up the drawbacks of RTK as it utilizes no more information than the images. SLAM can also be combined with the Inertial Measurement Unit (IMU) called Visual-Inertial SLAM (VI-SLAM,) with the improvement of accuracy and robustness. Therefore, our study mainly aims to confirm the feasibility of continuous positioning based on RTK and VI-SLAM with the Xiaomi MI 8. An application is developed to execute the functions, including logging images, measurements of IMU, and GPS measurements in Receiver INdependent EXchange (RINEX) format with the Xiaomi MI 8. The performances of RTK with and without the assistance of VI-SLAM are assessed respectively in the urban area. The experimental results demonstrate that the combination of RTK and VI-SLAM based on smartphones can effectively provide continuous positioning results. We believe our application will facilitate research and development in relation to positioning algorithms. Readers have access to this application at https://github.com/Nronaldo/CIGRLogger.

The Integration of GPS/BDS Real-Time Kinematic Positioning and Visual–Inertial Odometry Based on Smartphones

“…We proposed a continuous positioning algorithm based on RTK and visual-inertial SLAM (VI-SLAM) in our previous work [46]. The location part of VI-SLAM (VIO) is employed in [46] to assist RTK in urban areas.…”

“…We proposed a continuous positioning algorithm based on RTK and visual-inertial SLAM (VI-SLAM) in our previous work [46]. The location part of VI-SLAM (VIO) is employed in [46] to assist RTK in urban areas. While both our previous and current studies involve RTK and VIO, the strategies for combining them are different.…”

“…However, in our previous work, RTK and VIO do not run simultaneously, but alternate to estimate a positioning solution. The position output from RTK does not affect the output from VIO and vice versa [46]. In our previous work, we combined RTK with VIO in a straightforward and unreliable way.…”

“…Our previous work open sourced a CIGRLogger to collect images, IMU measurements, and GPS measurements. The GPS measurements are output in RINEX format and can be directly processed by RTKLIB, similar to what the GEO++ RINEX Logger does [46]. However, valid satellites in a single constellation are unable to meet the positioning requirements in urban areas.…”

High-Accuracy Position-Aware Robot for Agricultural Automation Using Low-Cost IMU-Coupled Triple-Laser-Guided (TLG) System

“…To effectively perform these complex open-field tasks, accurate and precise localization of these agricultural robots, including XYZ position, heading, and attitude (roll and pitch tilts), are essential. Several principles of localization sensors for agricultural robots are real-time kinematic global navigation satellite systems (RTK GNSS) [1]- [5], landmarks detection [6], light laser detection and ranging (LiDAR) [7]- [8], radar [9], sensor fusion with camera [10]- [13], ultrasonic [14], multi-sensor fusion [15]- [16], beacons based [17], localization and mapping (SLAM) [18], laser range finder (LRF) [19], and inertial measurement unit (IMU) [20]. Particularly, RTK GNSS coupled with inertial navigation systems (INS) is extensively employed by farmers due to its relatively higher accuracy and precision compared to other sensing techniques.…”