5 research outputs found
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Client-server-based LBS architecture: A novel positioning module for improved positioning performance
Permission to distribute obtained from publisher.This work presents a new efficient positioning module that operates over client-server LBS architectures. The
aim of the proposed module is to fulfil the position information requirements for LBS pedestrian applications
by ensuring the availability of reliable, highly accurate and precise position solutions based on GPS single
frequency (L1) positioning service. The positioning module operates at both LBS architecture sides; the client
(mobile device), and the server (positioning server). At the server side, the positioning module is responsible
for correcting userâs location information based on WADGPS corrections. In addition, at the mobile side,
the positioning module is continually in charge for monitoring the integrity and available of the position
solutions as well as managing the communication with the server. The integrity monitoring was based on
EGNOS integrity methods. A prototype of the proposed module was developed and used in experimental trials
to evaluate the efficiency of the module in terms of the achieved positioning performance. The positioning
module was capable of achieving a horizontal accuracy of less than 2 meters with a 95% confidence level
with integrity improvement of more than 30% from existing GPS/EGNOS services
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Precise positioning in real-time using GPS-RTK signal for visually impaired people navigation system
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 24/9/2010.This thesis presents the research carried out to investigate and achieve highly reliable and accurate navigation system of guidance for visually impaired pedestrians. The main aim with this PhD project has been to identify the limits and insufficiencies in utilising Network Real-Time Kinematic Global Navigation Satellite Systems (NRTK GNSS) and its augmentation techniques within the frame of pedestrian applications in a variety of environments and circumstances. Moreover, the system can be used in many other applications, including unmanned vehicles, military applications, police, etc. NRTK GNSS positioning is considered to be a superior solution in comparison to the conventional standalone Global Positioning System (GPS) technique whose accuracy is highly affected by the distance dependent errors such as satellite orbital and atmospheric biases.
Nevertheless, NRTK GNSS positioning is particularly constrained by wireless data link coverage, delays of correction and transmission and completeness, GPS and GLONASS signal availability, etc., which could downgrade the positioning quality of the NRTK results.
This research is based on the dual frequency NRTK GNSS (GPS and GLONASS). Additionally, it is incorporated into several positioning and communication methods responsible for data correction while providing the position solutions, in which all identified contextual factors and application requirements are accounted.
The positioning model operates through client-server based architecture consisted of a Navigation Service Centre (NSC) and a Mobile Navigation Unit (MNU). Hybrid functional approaches were consisting of several processing procedures allowing the positioning model to operate in position determination modes. NRTK GNSS and augmentation service is used if enough navigation information was available at the MNU using its local positioning device (GPS/GLONASS receiver).The positioning model at MNU was experimentally evaluated and centimetric accuracy was generally attained during both static and kinematic tests in various environments (urban, suburban and rural). This high accuracy was merely affected by some level of unavailability mainly caused by GPS and GLONASS signal blockage. Additionally, the influence of the number of satellites in view, dilution of precision (DOP) and age corrections (AoC) over the accuracy and stability of the NRTK GNSS solution was also investigated during this research and presented in the thesis.
This positioning performance has outperformed the existing GPS service. In addition, utilising a simulation evaluation facility the positioning model at MNU performance was quantified with reference to a hybrid positioning service that will be offered by future Galileo Open Service (OS) along with GPS. However, a significant difference in terms of the service availability for the advantage of the hybrid system was experienced in all remaining scenarios and environments more especially the urban areas due to surrounding obstacles and conditions.
As an outcome of this research a new and precise positioning model was proposed. The adaptive framework is understood as approaching an integration of the available positioning technology into the context of surrounding wireless communication for a maintainable performance. The positioning model has the capability of delivering indeed accurate, precise and consistent position solutions, and thus is fulfilling the requirements of visually impaired people navigation application, as identified in the adaptive framework
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Interface design for a remote guidance system for the blind: Using dual-screen displays
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The mobility for the visually impaired people is one of the main challenges that researchers are still facing around the world. Although some projects have been conducted to improve the mobility of visually impaired people, further research is still needed. One of these projects is Brunel Remote Guidance System (BRGS). BRGS is aimed to assist visually impaired users in avoiding obstacles and reaching their destinations safely by providing online instructions via a remote sighted guide.
This study comes as continuation of the development process of BRGS; the main aim that has been achieved of this research is the optimisation of the interface design for the system guide terminal. This helps the sighted guide to assist the VIUs to avoid obstacles safely and comfortably in the micro-navigation, as well as to keep them on the right track to reach their destination in the macro-navigation. After using the content analysis, the performance factors and their assessments method were identified in each BRGSâ element, which concluded that there is a lack of research on the guide terminal setup and the assessment method for the sighted guide performance. Furthermore, there are no model to assist the sighted guide performance and two-screen displays used in the literature review and similar projects. A model was designed as a platform to conduct the evaluation on sighted guide performance. Based on this model, the computer-based simulation was established and tested, which made the simulation is ready for next task; the evaluation of the sighted guide performance. The conducted study determined the effects of the two-screen displays on the recognition performance of the 80 participants in the guide terminal. The performance was measured with the context of four different resolution conditions. The study was based on a simulation technique, which is consisted of two key performance elements in order to examine the sighted guide performance; the macro-navigation element and the micro-navigation element. The results show that the two-screen displays have an effect on the performance of the sighted guide. The optimum setup for the two-screen displays for the guide terminal consisted of a big digital map screen display (4CIF [704p x 576p]) and a small video image screen display (CIF [352p x 288p]), which one of the four different resolutions. This interface design has been recommended as a final setup in the guide terminal
Interface design for a remote guidance system for the blind : using dual-screen displays
The mobility for the visually impaired people is one of the main challenges that researchers are still facing around the world. Although some projects have been conducted to improve the mobility of visually impaired people, further research is still needed. One of these projects is Brunel Remote Guidance System (BRGS). BRGS is aimed to assist visually impaired users in avoiding obstacles and reaching their destinations safely by providing online instructions via a remote sighted guide. This study comes as continuation of the development process of BRGS; the main aim that has been achieved of this research is the optimisation of the interface design for the system guide terminal. This helps the sighted guide to assist the VIUs to avoid obstacles safely and comfortably in the micro-navigation, as well as to keep them on the right track to reach their destination in the macro-navigation. After using the content analysis, the performance factors and their assessments method were identified in each BRGSâ element, which concluded that there is a lack of research on the guide terminal setup and the assessment method for the sighted guide performance. Furthermore, there are no model to assist the sighted guide performance and two-screen displays used in the literature review and similar projects. A model was designed as a platform to conduct the evaluation on sighted guide performance. Based on this model, the computer-based simulation was established and tested, which made the simulation is ready for next task; the evaluation of the sighted guide performance. The conducted study determined the effects of the two-screen displays on the recognition performance of the 80 participants in the guide terminal. The performance was measured with the context of four different resolution conditions. The study was based on a simulation technique, which is consisted of two key performance elements in order to examine the sighted guide performance; the macro-navigation element and the micro-navigation element. The results show that the two-screen displays have an effect on the performance of the sighted guide. The optimum setup for the two-screen displays for the guide terminal consisted of a big digital map screen display (4CIF [704p x 576p]) and a small video image screen display (CIF [352p x 288p]), which one of the four different resolutions. This interface design has been recommended as a final setup in the guide terminal.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
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Adaptive, reliable, and accurate positioning model for location-based services
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis presents a new strategy in achieving highly reliable and accurate position solutions fulfilling the requirements of Location-Based Services (LBS) pedestriansâ applications. The new strategy is divided into two main parts. The first part integrates the available positioning technology within the surrounding LBS application context by introducing an adaptive LBS framework. The context can be described as a group of factors affecting the application behaviour; this includes environmental states, available resources and user preferences. The proposed adaptive framework consists of several stages, such as defining the contextual factors that have a direct effect on the positioning performance, identifying preliminary positioning performance requirements associated with different LBS application groups, and introducing an intelligent positioning services selection function. The second part of this work involves the design and development of a novel positioning model that is responsible for delivering highly reliable, accurate and precise position solutions to LBS users. This new model is based on the single frequency GPS Standard Positioning Service (SPS). Additionally, it is incorporated within the adaptive LBS framework while providing the position solutions, in which all identified contextual factors and application requirements are accounted. The positioning model operates over a client-server architecture including two main components, described as the Localisation Server (LS) and the Mobile Unit (MU). Hybrid functional approaches were developed at both components consisting of several processing procedures allowing the positioning model to operate in two position determination modes. Stand-alone mode is used if enough navigation information was available at the MU using its local positioning device (GPS/EGNOS receiver). Otherwise, server-based mode is utilised, in which the LS intervenes and starts providing the required position solutions. At the LS, multiple sources of GPS augmentation services were received using the Internet as the sole augmentation data transportation medium. The augmentation data was then processed and integrated for the purpose of guaranteeing the availability of valid and reliable information required for the provision of accurate and precise position solutions. Two main advanced position computation methods were developed at the LS, described as coordinate domain and raw domain.
The positioning model was experimentally evaluated. According to the reported results, the LS through the developed position computation methods, was able to provide position samples with an accuracy of less than 2 meters, with high precision at 95% confidence level; this was achieved in urban, rural, and open space (clear satellite view) navigation environments. Additionally, the integrity of the position solutions was guaranteed in such environments during more than 90% of the navigation time, taking into consideration the identified integrity thresholds (Horizontal Alert Limits (HAL)=11 m). This positioning performance has outperformed the existing GPS/EGNOS service which was implemented at the MU in all scenarios and environments. In addition, utilising a simulation evaluation facility the developed positioning model performance was quantified with reference to a hybrid positioning service that will be offered by future Galileo Open Service (OS) along with GPS/EGNOS. Using the statistical t-test, it was concluded that there is no significant difference in terms of the position samplesâ accuracy achieved from the developed positioning model and the hybrid system at a particular navigation environment described as rural area. The p-value was 0.08 and the level of significance used was 0.05. However, a significant difference in terms of the service integrity for the advantage of the hybrid system was experienced in all remaining scenarios and environments more especially the urban areas due to surrounding obstacles and conditions