Assessment of Moving-Base Real-Time Kinematic (RTK) Positioning Using Low-cost Global Navigation Satellite System (GNSS) Receivers in Vehicle Heading Determination

Abstract

Abstract – In recent years, various studies have been conducted to evaluate the performance of low-cost GNSS receivers in comparison to high precision GNSS receivers in stationary base positioning. Since a setup with a moving-base has not been widely performed, this study intends to assess the use of multi-frequency low-cost GNSS receivers in a moving-base Real-Time Kinematic (RTK) positioning, specifically, in vehicle heading determination. A moving-base setup could provide not only the positions, but also the headings of the platform where the receivers are mounted. Vehicle heading is useful in many transport applications such as vehicle accident investigation. It could give information that may be used to examine a vehicle’s orientation history, among others. In this study, the respective antennas of two low-cost GNSS receivers were mounted on top of the vehicle 1.5 m apart, with the rover antenna located in front of the moving-base antenna. The receivers were configured for real-time transmission and reception of corrections. The vehicle travelled along an expressway and its real-time true headings were displayed in the u-center software. The heading outputs were validated by comparing to the manually computed headings using GNSS-derived positions from post-processed solution. The results showed that the Root Mean Square Error (RMSE) between the two heading datasets was 0.3258 degree which is almost equivalent to the expected accuracy of 0.33 degree. For a 4.8-m average length of car, this could translate to 0.03 m offset from center which is a considerable difference. To further validate the results, the average distance between the receivers, which was 1.4985 m, was compared to the actual baseline length of 1.5 m. The difference was 0.0015 m. The results indicate that the low-cost GNSS receivers can be used in a moving-base RTK positioning to provide accurate headings of the vehicle real-time, which could also be examined post-survey.

Keywords: RTK, moving-base RTK, relative positioning, GNSS, vehicle heading determination