Research On Key Technique Of Road Information Acquirement Based On Positioning And Electronic Map

Along with the increasing development of automotive technology, more and morerequest for riding comfort, dynamic performance and economic were put forward. In orderfor vehicles control system to make vehicles play a better performance, besides demandvehicles'state parameters, even need road conditions and driver's intention may be requiredto considered, therefore road environment information of vehicles current position requiredare captured at real time. But the methods of obtaining current road parameters almost havesome shortcomings. For example, historical driving road information can be distinguishedonly in some time, but it is difficult to acquire the changes of road conditions on traindirection ahead, or determine current precise road positions and so on. So either not preciseroad parameters obtained, or lack of real time when obtaining road parameters. At present,the precision of electronic map and richness information are quite abundant, electronic maphas been widely used in the world today. In this paper, a road information extractionsystem that can obtain at real time and pre-read road information has been established byusing GPS and electronic map's road parameters database information, laid a theoreticaland practical foundation for using these parameters into vehicle control system.With the popularity and development of satellite navigation and positioning technologywith an emphasis on GPS, as well as the increasing precision improvement of deadreckoning devices, a GPS+DR hybrid location technology makes it probable to locatemoving vehicles at real time.With the increasing development of GIS( geographic information system), cartographyand computer technology, high-precision electronic map has replaced traditional papermaps. At the same time, combined navigation and position information with electronic maptechnology can display vehicles current positions on electronic map, the derivation mapmatching technology has been widely used in the area of vehicle navigation, informationacquisition and measurement. In addition, high-speed computing chips have alreadyenabled us to obtain related information by high strength calculation.As mentioned above, after obtaining the information of specific vehicles roadnavigation and position information, train direction, combined with electronic map relevantto road parameters obtained, vehicles current position and road parameters on traindirection ahead can be obtained quickly and precisely. Combining road informationobtained with vehicles controlling system relevant to control information so that vehicleautomatic transmission system can respond on the basis of different road conditionseffectively and timely, not only enhance the adaptability of vehicle shifting control, but also adapt to drivers'intentions, which enhances riding comfort, dynamic and economicproperty.Obtaining the current road parameters information precisely and at tremendous speedwill enable automotive shifting to respond to different road situations such as road level,road surface material, the attachment of the road,the inflexion of the frontage,curvature ofthe road, etc timely and effectively. So that it enhanced the adaptability of shifting strategiesand robustness further, and improved the property of the vehicles'economic security andriding comfort further.In allusion to the problems of shifting strategy without introducing current roadparameters and eigenvalue in vehicles control system, in this paper, using positioninformation supplied by GPS and electronic map related data, road parameters informationwere extracted. It can provide road surface situation of road which current vehicle lies in,has supplied powerful parameter data for vehicles control system. Including the followingaspects:Part I: research for the extraction of GPS position information and data switching. Inorder to obtain vehicle road information, we must obtain current vehicle positioninformation using GPS position technology and verify information obtained. Becauseelectronic map format is the BJ-54 coordinate system in China which demandingconversion of coordinate using GPS position information extracted, so that it is probable todisplay current vehicle real-time position information on electronic maps. Because thissystem use local electronic map, of which the range of coordinate is relative small, fourparameters coordinate switching method is used. It can increase switching speed.Part II: analyzing and adding road parameter data format based on electronic map.Because of DBF which original electronic maps belonging to may not include such as roadlevel, road surface adhesion, etc relevant to parameter information. Therefore, we shallinsert necessary related information items manually and complete information storage inoriginal electronic maps, to extract related parameters in future use and the process ofcalling program and to avoid all kinds of errors which were caused by lack road parameterinformation or uncompleted.Part III: map matching and road parameter extraction. Because of some errors whenextracting current vehicle position information effectively and switching coordinate, currentvehicle position information can not be displayed precisely on electronic map, thus we shallestimate data effectively and reasonably by map matching method so that it is probable todisplay current vehicle position on electronic map accurately and quickly. After mapmatching, system will extract current vehicle road relevantly to parameter information. Toextract current vehicle road information accurately and quickly, and forecast vehicle roadahead by pre-reading mechanism, it is enable to implement road parameters acquirementquickly and effectively. Introducing pre-reading mechanism enable to solve the problems ofrelatively low system real-time which a great many floating point calculation lead to and timing sequence inconsistencies exist between computing results and vehicle parameters ata single moment in time.This system has achieved using demand a basically by debug and run. After loadingelectronic maps, it enable to extract road parameters on electronic maps accurately andintegrallty. Building integrated electronic map road parameter database can not only use toextract related road parameters, but also ensure vehicle current position by map matching.Road parameter database has avoided data storage redundancy by reasonable physicalstructure, at the same time, enhanced data access efficiency.Finally, after many testings, this paper has analyzed and concluded measurement data,established model simulation demonstrative system. This system enable to display roadsurface and driving situations that vehicle current position lies in on electronic maps at realtime. Experimental evidence shows that introducing road parameters into shifting strategyin vehicle automatic transmission system can deal with the problem of complicated roadsurface shifting frequently, and this way is effective and feasible.