Research Of Key Technologies About Portable Embedded Navigation Platform

With the rapid development of technologies, such as Internet, distributed computing, wireless communications,mobile computing and micro-mini-RTOS, the computer technology has gradually coming into our daily information tools, and the tools are more intelligent and powerful. The focus of information technology is shifting from the information management and storage to the information processing, integration and rapid access. In addition, more and more integrations of the spatial information are using in our society, positioning navigation system has been rapid developed and wider applied. Especially in the popular embedded navigation field, the role and its functions have been accepted. Embedded navigation systems is a multi-level system, it can be widely used in various types of car, hand-held, lightweight entertainment consumer products but also related to hardware, operating system, map data services, navigation applications and user interface. For the popular of wireless networks and improvement of urban information services, the integrated information services of embedded navigation system has become a key and indispensable part of daily life for families and society. Some embedded navigation-based intelligent transportation systems has well developing and using in many countries, they have played an important role in people's life. For the diversity of the current embedded hardware, operating system and the shortage of management of navigation electronic map data, there are many limitations and constraints in the course of function expansion of the navigation applications. Most navigation products are developed by different companies according to the different hardware and software design,that's made the navigation-based applications hard to meet the industry needs and scalability.Nowadays, the hardware manufacturers and navigation electronic map providers are doing main research of navigation systems,and the researches are mainly focused on the bundle development of specified platform. The main service method is navigation, the performance of productions is of greatly difference and the scalability is limited. In recent years, some software development platform of embedded GIS and navigation has appeared, but most of them are based on customized embedded operating system or specific hardware platform. At present the entire deeply system research of navigation is needed, but for the particularity of embedded navigation systems, some high-performance algorithms and data model research has far from meeting the needs of embedded navigation systems. The reasonable system architecture design, spatial information data model, effective organization and design of embedded systems with multi-module key technologies and the reasonable scheduling mechanism have become the important basis of navigation system, and the cross-platform embedded software development methodologies, multi-engine structure, rapid development and application have become the core content of the navigation system. Therefore, the systematical analysis and research on embedded hardware and embedded operating system, rational management on spatial data in the embedded field, the multi-engine design and integration, and the proper embedded software development technology, that is, to build embedded portable navigation platform is important way for fast development of embedded navigation systems.In this paper, combing with the National Natural Science Fund Project:Eleventh Five-Year National Support Scheme "the key technology research and demonstration of share the urban spatial information infrastructure ",focusing on research and design of embedded portable navigation platform with the core navigation capability, for solving the key technologies, such as the spatial data organization and management, the portability the software, the industry applications development and the expansion of popular service. With the comparison of embedded navigation systems, we discussed the spatial data organization model, the portable software development methods, the multi-engine design, navigation module design, achieved the rapid adaptability for different hardware platforms and software platform, developed our navigation electronic map physical storage format. On these bases, we studied the diverse data integration and management. With the needs of kernel navigations system, we realized the kernel modules such as positioning, path analysis and intelligent navigation. The use of enhanced extended file access module and efficient memory management module, with the stand-alone GUI engine, that makes the whole navigation platform can meet the most needs of navigation system or the applications based on navigation. Specifically the research works are as follows:(1)Analyzed the applications and development of embedded navigation systems, pointing out the integration of multi-technologies and the intelligentization is the main direction of navigation system, and the navigation electronic map data, wireless data transfer, industrial data integration, cross-platform development support are the key technologies of embedded navigation systems. Discussed the Embedded systems development technology, navigation and electronic map technologies, multi-engine technology and navigation technology, etc. are discussed, pointing out feasible of embedded portable navigation platform. Combing with the characteristics of spatial information services, the needs of industrial applications,even the rapid development of internet of things, we proposed necessity and importance of the portable embedded navigation platform in the current and future information society.(2) Analyzed the embedded navigation systems, discussed the application model, and given the hierarchical model of embedded navigation systems by the study of embedded logic of navigation map data classification, management, spatial indexing, path analysis, path navigation, and map display. To achieve the system's cross-platform, we concludes the characteristics of portable navigation platform, adopting the hardware abstraction layer and the operating system layer approach to achieve the independent hardware and system software design of navigation platform. Meanwhile, we studied the navigation electronic map by the analysis of road model, the physical storage format, and multi-data organization and management. Finally, we designed the modules such as GUI, road network analysis, GPS navigation, wireless communications, and build up the model of the portable navigation platform.(3)Using the abstraction layer design technology, integrate the embedded navigation platform with embedded hardware and embedded operating system, using the hardware abstraction layer technology to achieve the isolation of hardware platform and embedded operating system, using the operating system abstraction layer technology to archive the isolation of embedded operating system and navigation system. Discussing the involved works, such as message management, file interface design, especially the GUI window system. By using GAL and IAL to combine the hierarchical message and window management mechanism, and designed the independent window system. We finally realized a complete portability abstraction layer for cross-platform software development.(4)Combining the data management, discussed the principle of making the electronic map, the large map sheet map management and seamless splicing technology, studied the management of spatial data from the perspective of navigation systems and scheduling mechanism of data organization, proposed a data organization model for navigation applications and services expansion. By using the uniform grid index, organized the data in different layers with different scale to archive the continuous map browsing. Meanwhile, centralized store the packed data in parcels, according to the topology to reconnect the split road segment by using the IDT table to achieve the lossless storage of vector data compression. At the basis of the works, we discussed the physical storage format, combine the characteristics of embedded devices, designed our physical storage format of navigation map, concluded the methods of map data abbreviation, compressed the data and stored by bit format. The strategy of the simplified structure, bit format storage and sub-block compression made the data can meet the needs of navigations.(5) Proposed our multi-engine navigation architecture design, given their design models. The GDI display engine based on Frame-buffer can achieve the excellent performance in the visual map display and the independent GUI window system. The file access scheduler engine can provides the high-performance data supply for many modules. The memory management engine can achieve the small memory, lower-data access and high speed hit rate, it can provides the excellent performance in many different hardware platforms. The positioning and navigation engine satisfied the needs of many applications by the well designed GPS signal organization and management module, route analysis module and map-matching module. The platform is the result of using of multi-engine structures, the hierarchical and modular structure makes the platform can meet most business needs. The structure is the business core the support of the platform.(6) Realized the embedded portable navigation platform and developed several applications by using the platform. The portability, well organized multi-data storage, multi-engine and navigation structure of the platform are proved in these applications. What's more, the using of wireless network communication proved the capacity of expansion and development of the platform.