Support system for safe driving heavily depends
on global navigation satellite system. Pseudoranges between
satellites and vehicles are measured to compute vehicles&#x2019;
positions and their relative positions. In urban areas, however,
multipath errors (MPEs) in pseudoranges, caused by
obstruction and reflection of roadside buildings, greatly degrade
the precision of relative positions. On the other hand,
simply removing all reflected signals might lead to a shortage
of satellites in fixing positions. In our previous work,
we suggested solving this dilemma by cooperative relative
positioning (CoRelPos) which exploits spatial correlation of
MPEs. In this paper, we collected the trace data of pseudoranges
by driving cars in urban areas, analyzed the properties
of MPEs (specifically, their dependency on signal strength,
elevation angles of satellites, and receivers&#x2019; speeds), and highlighted
their spatial correlation. On this basis, the CoRelPos
scheme is refined by considering the dynamics of MPEs. 
Evaluation results under practical vehicular scenarios confirm
that properties of MPEs can be exploited to improve
the precision of relative positions.

Suhua Tang

Nao Kawanishi

Rei Furukawa

Nobuaki Kubo

Experimental Evaluation of Cooperative Relative Positioning for Intelligent Transportation System

Electric wheelchair is one of the many engines used for the movement of aged and disabled people. This paper introduces an obstacle avoidance using deformable virtual zone (DVZ), particle filter to improve localization and fuzzy controller to join desired target. This controller is developed to increase the independence of disabled and aged people, specifically those who suffer not only disability in the lower limbs but also visual disturbances. To overcome these problems, different perceptive abilities or sensors were introduced. In this context, we developed a control system composed by fuzzy controller to join a target, DVZ method for obstacle avoidance, and particle filter for localization. Also, we present the simulation results of the wheelchair navigation system.

Malek Njah

Mohamed Jallouli

Combination of the DVZ Method, Particle Filter, and Fuzzy Controller for Electric Wheelchair Navigation

Satellite navigation is critical in signal-degraded environments where signals are corrupted and GNSS systems do not guarantee an accurate and continuous positioning. In particular measurements in urban scenario are strongly affected by gross errors, degrading navigation solution; hence a quality check on the measurements, defined as RAIM, is important. Classical RAIM techniques work properly in case of single outlier but have to be modified to take into account the simultaneous presence of multiple outliers. This work is focused on the implementation of random sample consensus (RANSAC) algorithm, developed for computer vision tasks, in the GNSS context. This method is capable of detecting multiple satellite failures; it calculates position solutions based on subsets of four satellites and compares them with the pseudoranges of all the satellites not contributing to the solution. In this work, a modification to the original RANSAC method is proposed and an analysis of its performance is conducted, processing data collected in a static test.

Gaetano Castaldo

Antonio Angrisano

Salvatore Gaglione

Salvatore Troisi

P-RANSAC: An Integrity Monitoring Approach for GNSS Signal Degraded Scenario

Vehicle navigation systems usually simply function by calculating the shortest fastest route over a road network. In contrast, pedestrian navigation can have more diverse concerns. Pedestrians are not constrained to road/path networks; their route may involve going into buildings (where accurate satellite locational signals are not available) and they have different priorities, for example, preferring routes that are quieter or more sheltered from the weather. In addition, there are differences in how people are best directed: pedestrians noticing landmarks such as buildings, doors, and steps rather than junctions and sign posts. Landmarks exist both indoors and outdoors. A system has been developed that uses quick response (QR) codes affixed to registered landmarks allowing users to localise themselves with respect to their route and with navigational instructions given in terms of these landmarks. In addition, the system includes images of each landmark helping users to navigate visually in addition to through textual instructions and route maps. The system runs on a mobile device; the users use the device&#x2019;s camera to register each landmark&#x2019;s QR code and so update their position (particularly indoors) and progress through the route itinerary.

Anahid Basiri

Pouria Amirian

Adam Winstanley

The Use of Quick Response (QR) Codes in Landmark-Based Pedestrian Navigation

A three-dimensional matrix method is proposed in this paper for Global Navigation Satellite System (GNSS) constellation Intrasatellite Link (ISL) topological design. The rows and columns of proposed matrix contain the information of both constellation orbit planes and satellites in each orbit plane. The third dimension of proposed matrix represents the time sequences during constellation movement. The proposed method has virtues of better advantage of conceptual clarity and computational efficiency, meanwhile, some properties of ISLs in the constellation can be proved easily. At the second part of this paper, a link assignment and optimal routing problem is proposed using three-dimensional topology matrixes, which aimed to minimize the relay hops during the process of data uploading to whole constellation network. Moreover, some practical constrains as antenna beam coverage and relative velocity are considered and analyzed in detail. Finally, some numerical simulations are provided, and the results demonstrated the promising performance of proposed topological method in reduction of computation burden, clear ISL conception, and so forth; the efficiency of provided optimal ISL routing problem is also proved.

Xiaoliang Wang

Yansong Meng

Zhe Su

Gang Wang

Lixin Zhang

Deren Gong

A Simple Three-Dimensional Matrix Method for Global Constellation Intrasatellite Link Topological Design

Radio frequency interference detection and mitigation are becoming of paramount importance due to the increasing number of services and applications based on the position obtained by means of Global Navigation Satellite Systems. A way to cope with such threats is the implementation in the receiver of advanced signal processing algorithm able to raise proper warning or improve the receiver performance. In this paper, we propose a method based on the Wavelet Transform able to split the useful signal from the interfering component in a transformed domain. The wavelet packet decomposition and proper statistical thresholds allow the algorithm to show very good performance in case of multiple pulse interference as well as in the case of narrowband interference, two scenarios in which traditional countermeasures might not be effective.

Luciano Musumeci

Fabio Dovis

Use of the Wavelet Transform for Interference Detection and Mitigation in Global Navigation Satellite Systems

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International Journal of Navigation and Observation - Table of contents 2014

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International Journal of Navigation and Observation