Demonstrating Performance Levels of Positioning Technologies

Transcription

1 Demonstrating Performance Levels of Positioning Technologies Version 2.1 June 2009 GMV Aerospace and Defence S.A. c/ Isaac Newton 11 P.T.M. - Tres Cantos E Madrid SPAIN Tel.: Fax: Web:

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3 WHAT IS POLARIS? The use of additional sensors and systems with GNSS improves navigation performances and open the way for new mass-market and professional applications. The demonstration of the levels of performance that can be expected using current and future positioning technologies will create new opportunities for industry. polaris is a software tool that allows the rapid evaluation of navigation performances for different user applications in different environments polaris provides the means to demonstrate the benefits to be gained with a wide variety of combinations of systems and sensors in different user environments. polaris has been designed to cope with the different levels of expertise. A non-expert user of the tool will be able to assess the performance any combination of standard navigation devices in their particular operating environment. The navigation expert will also have the added advantage of being able to fine tune the individual components for a more rigorous analysis, particularly in terms of the GNSS and SBAS elements, thanks to polaris advanced Graphical User Interface (GUI)

4 A GIS Facility and a 3D Tool allow working with real application environments, including low visibility conditions like urban canyons. A dedicated module, the GNSS&UA simulator, is in charge of evaluating the navigation performances. Algorithms have been optimised to minimise simulation execution time so you do not have to wait hours (for typical analyses) to get simulation results. GNSS & UA Simulator Graphical User Interface GIS Cartography GIS Facility 3D Subsystem - 4 -

5 WHAT IS POLARIS INTENDED FOR? Feasibility Studies Before embarking on costly revisions to the existing navigation services it is necessary to know in advance what enhancements can be expected, and which may ultimately not lead to significant improvements. Use polaris from the very beginning of the feasibility phase. Perform trade-offs between different implementation options (e.g., positioning technologies to be used) and parametric analyses to support feasibility and cost-benefit studies. Present results in a clear and understandable manner to help making a Go/No Go decision. polaris has been used as well in several feasibility analyses commissioned by ESA and the European Commission. These studies were aimed at analysing integration of EGNOS into Galileo, and the extension of EGNOS outside the European Civil Aviation Conference (ECAC) area. Get User s Feedback System/application design has to be driven by user requirements. Linking potential users with system/application designers is essential to ensure that the final product becomes what the final users truly need. However many users do not - 5 -

6 have a technical background on positioning technologies. In particular, this represents a serious problem for market analyses. Use polaris facilities to show users in a clear manner how they can benefit from the product in question. In doing so it will be easier for them to provide feedback for system/application definition and design. polaris results can be easily used to prepare market surveying questionnaires, and can itself be used for surveying users during market analysis campaigns. polaris provides simulation results in many user-friendly graphical ways (coloured maps, X-Y plots, bar charts, etc.), including 3D scenarios in the VRML format. The Graphical User Interface has been designed to cope with different levels of expertise, which makes polaris the ideal tool to survey future users. Moreover, polaris can be even used as a powerful e-learning tool. 95 th Percentile of the number of satellites in view for GPS (assuming a constellation of 24 satellites) and Galileo+GPS over a urban area (centre of Madrid) and distribution of the percentile over the area in question. GPS Galileo + GPS - 6 -

7 Support System and Application Design The primary purpose of computer simulations is to validate the high level as well as the low level specifications. In addition, they also allow for specific design optimisation and the analysis of critical design issues. In the initial phases service volume simulations are used to define the service coverage scope and characteristics. Simulations are used for the dimensioning of the system as well as the determination of the achievable navigation performances. Whilst current simulators are focusing on the GNSS global component, they do not allow simulating regional and local component contributions, not to mention the different sensors (like odometers) that can be frequently found in many massmarket and professional applications. It is known that the use of Galileo (used alone or in combination with GPS) will not meet many application requirements, which will need to use additional systems and sensors, and thus the inclusion of these navigation aids have to be considered. Evaluate navigation performances including both navigation systems and sensors. Support performance budget definition and optimisation to refine system and error budgets requirements. Support high-level system design Test whether current design meets system/user requirements or not Optimise ground infrastructure, in terms of number of stations, distribution and characteristics Contribute to system deployment planning Contribute to performance validation - 7 -

8 Evaluate the same application with different user terminal characteristics (GNSS receivers, sensor quality, etc.), ground infrastructure (number and distribution of DGNSS stations, pseudolites, etc.), allowing savings in costly demonstration equipment Anticipate possible system evolutions (additional services, technology improvements, etc) and their impact on system design polaris is being used in the frame of the Galileo programme for performance assessment activities, providing feedback to system design (constellation definition in terms of satellite positions, spare philosophy, service error budgets assessment, etc) and In-Orbit Validation (IOV) planning. For instance, it is possible to analyse a GNSS constellation consisting of 4 satellites (for instance, during in-orbit validation phase). polaris is representing the percentage of times that vertical accuracy values are below 100 meters. The possibility of analysing the impact of GNSS receiver contributions makes polaris of invaluable help for GNSS manufacturers. Using polaris they can establish upper bounds for the different error components, checking their impact on navigation performances for different applications and in different user environments. polaris allows the generation of simulated trajectories according to a Gauss- Markov model. Starting from a reference ( true reference ) trajectory, polaris implements statistical models (Gauss-Markov process) to generate a possible realisation of that trajectory, consistent with the combination of systems used

9 The figure on the right corresponds to a simulated trajectory, as a user receiver would compute it (according to the conditions configured for error budgets and environment). The true (reference) trajectory is shown on the left. This feature opens the possibility of going beyond performance assessment to allow polaris users test their own algorithms such as RAIM, map-matching, road tolling, sensor hybridisation, and so on. Promote Navigation Systems and Applications There are many pilot projects aimed at demonstrating the benefits of satellite navigation in different applications. Obviously they can only make use of GPS, or GPS plus wide and local area augmentations as a maximum. Add maps, graphics and animations generated with polaris to your product documentation, brochures, web site, etc. Give a voice to potential users showing in an easy and understandable manner how they can benefit from the proposed solution

10 Best of all, you can do this even before the system is available, paving the way to market penetration and product commercialisation. If the system is expected to improve or complement an existing one, conduct data campaigns with the existing solution, reproduce results with polaris and simulate the situation with the system being proposed. The figure on the left represents the number of EGNOS GEO satellites in view over a given urban area. Simulation results showed that 24% of user locations cannot receive the EGNOS signal through GEO satellites. Systems (like SISNeT) for wireless dissemination of SBAS corrections may be the solution. Using polaris it is possible to, first of all, evaluate those applications using GPS, or GPS plus augmentations, and compare the results with real data to demonstrate confidence in the simulation results. Then it is straightforward to simulate the same applications with Galileo in order to demonstrate the benefits to be gained. It is even possible to evaluate the same application with different user terminal characteristics (GNSS receivers, sensor quality, etc.), ground infrastructure (number and distribution of DGNSS stations, pseudolites, etc.), allowing savings in costly demonstration equipment

11 SYSTEMS AND SENSORS SUPPORTED The following navigation systems are supported: GNSS systems, like GPS or Galileo Regional differential corrections (SBAS), like EGNOS or WAAS Local differential corrections (differential GNSS) Local augmentations, including pseudolites and radio mobile (GSM / GPRS / UMTS) positioning When evaluating dynamic (i.e., non-static) applications it is also possible to include sensors and see their effect on navigation performances. Among the sensors supported we can find odometers, gyroscopes, gyrocompasses and much more. polaris provides default configurations for all the systems and sensors mentioned before. Default configurations are provided for the following systems: GNSS: Fully characterised (constellation and navigation services) Galileo, GPS and GPS III. Default GNSS user receivers available for all services defined. SBAS: EGNOS (European Geostationary Overly Service) Local Elements: Like the DGPS network of the Spanish Port Authority. Sensors: default low, mid and high grade heading and distance sensors In addition, users have the option to define elements from polaris GUI. polaris users can set up any parameter affecting navigation performances computation

12 USER ENVIRONMENTS polaris can evaluate applications both over service areas (grid of static user terminals) and along trajectories. In both cases they can be defined using the GIS Facility. Trajectories can be defined just by selecting waypoints. polaris will compute the shortest trajectory joining those waypoints. Since a significant number of applications take place in urban areas, where masking angle conditions affect navigation performances, the option of simulating 3D environments (and, in particular, urban canyons) is a must. The use of 3D GIS data may not be justified, nor critical, in some cases given the average expense of such maps, such as when evaluating an application in a typical urban environment. For those situations, polaris includes a tool to create 3D environments starting from 2D GIS maps, the 3D Environments Tool Lite

13 The 3D Environments Tool (Lite version) allows creating 3D urban canyons starting from 2D GIS maps. The user selects an area within the map and height conditions (constant or random within a given range). The tool generates the visibility conditions to be used later during simulations

14 EVALUATING NAVIGATION PERFORMANCES In order to evaluate an application, the first thing to do is to define the combination of systems and sensors to be used, the user terminal characteristics and the service area or trajectory. In polaris jargon, this is called a scenario. Users can define multiple analyses for the scenario in question. Obtain Accuracy, Dilution of Precision (DOP) and number of navigation signals received for given availability levels (percentiles). Vertical, horizontal, long-track, cross-track, positioning, timing and global accuracies and DOP can be computed. Conversely, obtain availability figures for given threshold values. Compute protection levels according to WAAS-MOPS definitions. Compute availability of Galileo services based on the Galileo integrity concept (Hazardous Misleading Information, or HMI, and number of critical satellites). Compute the continuity risk (availability computations only)

15 VISUALISING SIMULATION RESULTS polaris provides a powerful and user-friendly facility for visualising and analysing simulation results: Coloured maps generated with the GIS facility, which can be exported to graphic files (JPEG format)

16 Bar charts to gather information for different Figures of Merit (e.g., several availability levels) or different scenarios (trade-offs and parametric analyses) Merit. XY-Plots to represent the evolution (along trajectories) of the Figures of

17 Navigate through 3D environments containing simulation results (using the Virtual Reality Mark-up Language, VRML). Produce reports summarising simulation results. Since they are in the HTML format, it is quite easy to include them in your own documents. Easily export simulation results to plain text files, and post-process and represent them with your favourite software

18 OTHER FEATURES polaris runs on any standard PC or laptop under Windows 2000 and Windows XP operative systems. Detailed on-line help and user manual, with more than 360 pages. Wizard for first-time users Easily share elements, scenarios and simulations; download sample files from polaris website

19 Generate HTML reports for each component, scenario or simulation defined in the system

20 A HISTORY OF SUCCESS 1999 First release of GMV s elcano, polaris predecessor 2000 elcano V2 releases allowing, among other things, the assessment of RAIM availability and navigation performances in urban canyons First version of polaris released. Full Service Volume Simulator supporting GNSS/SBAS/DGNSS and local elements (pseudolites and mobile radio positioning) polaris v2 released. It now allows including sensors for navigation performance assessment at user level. Inclusion of the Galileo integrity concept (HMI) ESA procures polaris for the Radio Navigation Laboratory, at the European Space Research and Technology Centre (ESTEC) in the Netherlands Customized version of polaris for ESA (polaris V3). polaris is used (in different ways) in the following projects: Galileo B and C/D/E1 phases Extension of SBAS systems (EGNOS) to South-America and North-Africa, in the frame of the GEM project. Feasibility studies, like ARMAS (road tolling applications based on GNSS), SCORE (vehicle and pedestrian applications for E-112 emergency calls) and ADvantis (centralised guaranteed integrity localisation services) GRAS (Galileo Road Application Simulator), for in-car telematic systems and services

21 2007 GMV engineers use polaris to support the development of Galileo GMS OSPF and IPF (error budget allocation and expected impact at user level). They investigate alternative integrity concepts in response to the problems they face during OSPF/IPF design polaris is used in the frame of the SACCSA project under ICAO (Internal Civil Aviation Organization) contract to support the feasibility analysis of an SBAS system in Latin America by Contributing to define the ground station network distribution Assessing the navigation performances to be obtained polaris V4 released. polaris is endowed wit one of its most powerful capabilities: the generation of simulated trajectories and errors. This paves the way for new astonishing applications of polaris (e.g. testing new RAIM algorithms, map-matching, etc) polaris is used in the frame of the phase III of ESA s ARMAS project. Transport for London (TfL) engaged with ESA in order to cooperate toward the use of polaris in the prediction of Galileo performance in London. polaris V4 is used in ESA s GNSS Evolution Programme. Thanks to the implication of GMV engineers in the Programme, GMV generates internal (developer) versions of the SW to test the different ideas proposed in: CAGIR, aimed at studying the use of C band for GNSS systems The Multi-Regional augmentation System (MRS), which aims at providing SBAS services and regional integrity considering the future GNSS constellations

22 GETTING ADDITIONAL INFORMATION In order to get additional information about polaris, or request evaluation copies of the software, please visit Alternatively, you can also contact GMV by fax or letter: (FAO Marketing Department) GMV, S.A. c/ Isaac Newton 11 P.T.M. Tres Cantos Madrid SPAIN Ph Fax