GPS/BDS RTK Positioning Based on Equivalence Principle Using Multiple Reference Stations

Abstract

Reliable real-time kinematic (RTK) is crucially important for emerging global navigation satellite systems (GNSSs) applications, such as drones and unmanned vehicles. The performance of conventional single baseline RTK (SBRTK) with one reference station degrades greatly in dense, urban environments, due to signal blockage and multipath error. The increasing use of multiple reference stations for kinematic positioning can improve RTK positioning accuracy and availability in urban areas. This paper proposes a new algorithm for multi-baseline RTK (MBRTK) positioning based on the equivalence principle. The advantages of the solution are to keep observation independent and increase the redundancy to estimate the unknown parameters. The equivalent double-differenced (DD) observation equations for multiple reference stations are firstly developed through the equivalent transform. A modified Kalman filter with parameter constraints is proposed, as well as a partial ambiguity resolution (PAR) strategy is developed to determine an ambiguity subset. Finally, the static and kinematic experiments are carried out to validate the proposed algorithm. The results demonstrate that, compared with single global positioning system (GPS) and Beidou navigation system (BDS) RTK positioning, the GPS/BDS positioning for MBRTK can enhance the positioning accuracy with improvement by approximately (45%, 35%, and 27%) and (12%, 6%, and 19%) in the North (N), East (E), and Up (U) components, as well as the availability with improvement by about 33% and 10%, respectively. Moreover, the MBRTK model with two and three reference receivers can significantly increase the redundancy and provide smaller ambiguity dilution of precision (ADOP) values. Compared with the scheme-one and scheme-two for SBRTK, the MBRTK with multiple reference receivers have a positioning accuracy improvement by about (9%, 0%, and 6%) and (9%, 16%, and 16%) in N, E, and U components, as well as the availability improvement by approximately 10%. Therefore, compared with the conventional SBRTK, the MBRTK can enhance the strength of the kinematic positioning model as well as improve the positioning accuracy and availability.

BDS/GPS Multi-Baseline Relative Positioning for Deformation Monitoring

“…Finally, the IF ambiguity-fixed solution was obtained. The observation redundancy is considerably increased by the multi-GNSS MBS compared to the single-GNSS SBS [26]. Using more observations inevitably increases the AR dimension.…”

“…For example, Amin et al [25] employed the MBS model to increase the reliability of GPS monitoring networks by adopting a uniform datum and eliminating synchronous baseline closure errors in the optimal design of large GNSS control networks. Wang et al [26] enhanced the availability of RTK positioning by roughly 10% using a multi-reference station constraint algorithm based on the equivalence principle in autonomous vehicle navigation. Fan et al [27] proposed a dual-antenna RTK algorithm with baseline vector constraint to improve the system ambiguity resolution (AR) success rate from 48 to 85%.…”