The integrated navigation system with strapdown inertial navigation system (SINS), Beidou (BD) receiver and Doppler velocity log (DVL) can be used in marine applications owing to the fact that the redundant and complementary information from different sensors can markedly improve the system accuracy. However, the existence of multisensor asynchrony will introduce errors into the system. In order to deal with the problem, conventionally the sampling interval is subdivided, which increases the computational complexity. In this paper, an innovative integrated navigation algorithm based on a Cubature Kalman filter (CKF) is proposed correspondingly. A nonlinear system model and observation model for the SINS/BD/DVL integrated system are established to more accurately describe the system. By taking multi-sensor asynchronization into account, a new sampling principle is proposed to make the best use of each sensor’s information. Further, CKF is introduced in this new algorithm to enable the improvement of the filtering accuracy. The performance of this new algorithm has been examined through numerical simulations. The results have shown that the positional error can be effectively reduced with the new integrated navigation algorithm. Compared with the traditional algorithm based on EKF, the accuracy of the SINS/BD/DVL integrated navigation system is improved, making the proposed nonlinear integrated navigation algorithm feasible and efficient.

A Strapdown Interial Navigation System/Beidou/Doppler Velocity Log Integrated Navigation Algorithm Based on a Cubature Kalman Filter

Relative position awareness is a vital premise for the implementation of emerging intelligent transportation systems, such as collision warning. However, commercial global navigation satellite systems (GNSS) receivers do not satisfy the requirements of these applications. Fortunately, cooperative positioning (CP) techniques, through sharing the GNSS measurements between vehicles, can improve the performance of relative positioning in a vehicular ad hoc network (VANET). In this paper, while assuming there are no obstacles between vehicles, a new enhanced tightly coupled CP technique is presented by adding ultra-wide bandwidth (UWB)-based inter-vehicular range measurements. In the proposed CP method, each vehicle fuses the GPS measurements and the inter-vehicular range measurements. Based on analytical and experimental results, in the full GPS coverage environment, the new tight integration CP method outperforms the INS-aided tight CP method, tight CP method, and DGPS by 11%, 15%, and 24%, respectively; in the GPS outage scenario, the performance improvement achieves 60%, 65%, and 73%, respectively.

http://iopscience.iop.org/article/10.1088/0957-0233/26/4/045003/pdf

An ultra-wide bandwidth-based range/GPS tight integration approach for relative positioning in vehicular ad hoc networks

Satellite navigation is quickly becoming a multidimensional complex challenge, with four Global Navigation Satellite Systems (GNSS) fully or partially deployed, more than 90 GNSS satellites currently in the sky, and 12 open-service GNSS signal types available to the end-user. Research papers about GNSS performance typically focus on single or dual GNSS solutions, and there are still very few papers addressing jointly the four existing GNSS together. It is the goal of our paper to present a unified, fast, modular, and simple-to-program theoretical analysis of the four GNSS, focusing on performance limits in terms of spectral characteristics, tracking, multipath robustness, and positioning accuracy. A unified new compact approach for dealing with all the modulations employed in GNSS is also included.We show a unified generic framework for analyzing the multi-GNSS signals in a fast and simple-to-implement manner, without the need of simulating constellations or gathering measurement data. Our approach is also validated with Spectracom-based constellation data. Our analysis can be used as the starting point in further design process or system analysis.

Accuracy limits in multi-GNSS

In providing acceptable navigational solutions, Location-Based Services (LBS) in land navigation rely mostly on integration of Global Positioning System (GPS) and Inertial Navigation System (INS) measurements for accuracy and robustness. The GPS/INS integrated system can provide better land-navigation solutions than the ones any standalone system can provide. Low-cost Inertial Measurement Units (IMUs), based on Microelectromechanical Systems (MEMS) technology, revolutionized the land-navigation system by virtue of their low-cost miniaturization and widespread availability. However, their accuracy is strongly affected by their inherent systematic and stochastic errors, which depend mainly on environmental conditions. The environmental noise and nonlinearities prevent obtaining optimal localization estimates in Land Vehicular Navigation (LVN) while using traditional Kalman Filters (KF). The main goal of this paper is to effectively eliminate stochastic errors of MEMS-based IMUs. The proposed solution is divided into two main components: (1) improving noise cancellation, using advanced stochastic error models in MEMS-based IMUs based on combined Autoregressive Processes (ARP) and first-order Gauss-Markov Process (1GMP), and (2) modeling the low-cost GPS/INS integration, using a hybrid Fuzzy Inference System (FIS) and Second-Order Extended Kalman Filter (SOEKF). The results obtained show that the proposed methods perform better than the traditional techniques do in different stochastic and dynamic situations.

/pdf/a-new-technique-for-integrating-mems-based-low-cost-imu-and-oya50y8ex8.pdf

A new technique for integrating MEMS-based low-cost IMU and GPS in vehicular navigation

The application of GPS in bridge monitoring aims to determine accurately and precisely the response of the deck and towers of the bridge, and estimate the main response characteristics (amplitude, and modal frequencies). The main requirement of GPS monitoring is a high level of accuracy and availability of fixed solutions, which ensure the reliable operation of GPS and result in the precise estimation of the bridge’s response. However, the derived GPS time series of bridge monitoring can be contaminated by noise, due to the performance of the GPS satellite(s), the geometry of the GPS satellite constellation and the potential obstructions due to the bridge elements, which can even lead to GPS solution of poor accuracy and/or precision and result in reduced efficiency of the performance of the GPS monitoring. This study investigates the potential contribution of other GNSS constellations for a more robust and reliable displacement time series solution, derived from multi-GNSS records. More specifically, a novel method is developed to derive the optimal combination of GNSS records to determine the GNSS displacement time series based on checks of parameters which reflect the geometry of the satellite constellation and the quality of the GNSS satellites signals. The method is applied in monitoring of the Severn Suspension Bridge, in the UK, and it is revealed the enhancement in the GNSS monitoring performance of the bridge response for specific time-intervals for various locations on the bridge’s support towers, suspension cables and deck.

Monitoring the response of Severn Suspension Bridge in the United Kingdom using multi‐GNSS measurements

Till recently, for civil users worldwide, GPS was the only Global Navigation Satellite System (GNSS) for positioning purposes. However, the return of GLONASS as well as the appearance of Galileo and Beidou has brought many modern and advanced positioning services to the world. More importantly, the combinations of these systems in common multi-GNSS solutions promise much improvement in accuracy, availability and reliability of the positioning. This paper presents research works on development of multi-GNSS positioning solutions working with real signals collected from the recently launched satellites of the new Galileo and Beidou systems. The result analyses prove not only the readiness of the developed multi-GNSS solutions but also their real advantages over the stand-alone solutions.

Development of real multi-GNSS positioning solutions and performance analyses

Since December 27, 2012, the Beidou Navigation Satellite System officially started to operate. This event is a great opportunity for researchers in South East of Asia to receive and analyze the Beidou signals. After the official statement, the researchers at NAVIS centre monitored the broadcasted signal by using NAVISOFT- our Software Radio Receiver. This paper shows the analysis on the navigation message that was broadcasted by the Beidou satellites on the B1I bandwidth. In general, we were able to observe a valid ephemeris data on visible satellites. The successful PVT computation by using combinations of GEO and MEO/IGSO in static condition through code-phase measurements is indicated in this paper.

Duc Minh Truong

Papers

Development of real multi-GNSS positioning solutions and performance analyses

Recent results in receiving and decoding signals from the Beidou system

The tensor-train mimetic finite difference method for three-dimensional Maxwell's wave propagation equations