Automotive navigation system | EPFL Graph Search

An automotive navigation system is part of the automobile controls or a third party add-on used to find direction in an automobile. It typically uses a satellite navigation device to get its position data which is then correlated to a position on a road. When directions are needed routing can be calculated. On the fly traffic information (road closures, congestion) can be used to adjust the route. Dead reckoning using distance data from sensors attached to the drivetrain, an accelerometer, a gyroscope, and a magnetometer can be used for greater reliability, as GNSS signal loss and/or multipath can occur due to urban canyons or tunnels. Mathematically, automotive navigation is based on the shortest path problem, within graph theory, which examines how to identify the path that best meets some criteria (shortest, cheapest, fastest, etc.) between two points in a large network. Automotive navigation systems are crucial for the development of self-driving cars. Automotive navigation systems represent a convergence of a number of diverse technologies, many of which have been available for many years, but were too costly or inaccessible. Limitations such as batteries, display, and processing power had to be overcome before the product became commercially viable. 1961: Hidetsugu Yagi designed a wireless-based navigation system. This design was still primitive and intended for military-use. 1966: General Motors Research (GMR) was working on a non-satellite-based navigation and assistance system called DAIR (Driver Aid, Information & Routing). After initial tests GM found that it was not a scalable or practical way to provide navigation assistance. Decades later, however, the concept would be reborn as OnStar (founded 1996). 1973: Japan's Ministry of International Trade and Industry (MITI) and Fuji Heavy Industries sponsored CATC (Comprehensive Automobile Traffic Control), a Japanese research project on automobile navigation systems. 1979: MITI established JSK (Association of Electronic Technology for Automobile Traffic and Driving) in Japan.

NAVAROU - Potentiel d'utilisation des données routières de la navigation automobile pour l'entretien routier

Pierre-Yves Gilliéron

Car navigation is a field in broad expansion and the industry quickly developed a standard to model cartographic data useful for the applications of the road transport telematics: GDF, Geographic Data Files. Since its first version in 1988, GDF became an ISO standard in 2004, written by the technical committee TC 204. Consequently, the providers of data for navigation (Tele Atlas and Navteq) improved the content of their cartographic products by covering the road networks of the most part of the countries. Thus, this data model and its content are considered as a reference for many computer applications of navigation and management of the road and traffic. This project aims to evaluate the potential of ISO-GDF for the road information system (SIR) in Switzerland, from which the basic concepts (location, topology, geometry) are described in the standards SN 640.910 and following. The first part of the project is focused on the formulation of the requirements in terms of data for the road networks for the main business processes of road maintenance management. This step allowed to highlight classes of objects described in the GDF data model. The second step is a comparison between the definitions and data models described in VSS standards about the SIR and the content of ISO-GDF standard. This semantic and conceptual study checks the degree of compatibility between the data and the models according to the basic criteria: geometry, topology, attributes and space location. Based on this comparison, the study shows the potential benefits of the coupling between the data according to the GDF standard with basic data from the SIR. This third step aims at applying procedures to transfer and transform GDF data set into a format compatible with VSS standards for the spatial location, the geometry of the axes and the topology of the road network. These concepts of coupling were partially used by the project MISTRA for the import of basic data of GDF type. The fourth part deals with the management of GDF type data combined with data from the SIR. Several scenarios are described according to the type of operation (import, update, manipulation) and according to the contents existing beforehand in the SIR. The last part focuses on legal and organisational aspects which are fundamental elements when an information system, managed by a public administration, assimilates data of the GDF type coming from a private supplier. By its methodical approach, this project allows a comparison of models and definitions of road objects by highlighting the degrees of compatibility, while showing the practical features offered by the mechanisms of coupling. The choice of project MISTRA to integrate basic data of GDF type fully illustrates the growing role of data from private cartographic suppliers in the management of public infrastructures. However, the management of multiple data sources (public, private) in a SIR remains a complex operation about update and manipulation. In this context, the public-private partnerships can only extend in order to guarantee a quality of services for the road infrastructures and traffic management.

2008

Two degrees of freedom miniaturized gyroscope based on active magnetic bearings

Thomas Bosgiraud

The introduction of the active blocking system, better known as ABS, into cars revealed the growing need for inertial sensing. Among other data, that permit to apprehend the movements of a vehicle, the measurement of the vehicle angular velocity describes the change rate of the vehicle attitude. This measurement has been called by Foucault in 1852 gyroscopic sensing (from the Greek words σκοπειν = observe and γυρος = rotation). The currently available gyroscopes are either very high precision instruments (hence very costly), used in planes, or cheaper products but with a lack of sensitivity to be used in vehicle navigation. Therefore, a real need for gyroscopes combining low cost and precision exists. This thesis proposes to develop a gyroscope based on miniaturized active magnetic bearings (AMB). The advantage of such a device is that the spun mass will be levitated what frees it from any mechanical link to the base of the instrument what render precise classical mechanical gyroscopes so expensive. This thesis presents two prototypes of AMB based gyroscopes. The first one relies on the ball orbit sensing method which is a new theory proposed in this work. Because of the uncertainties due to the nonlinearities inherent to active magnetic bearings, the position of the levitated mass is adaptively controlled. Measurements performed on the prototype have demonstrated the feasibility of this solution with a ball following either a circular or a vertical orbit. The second designed prototype relies on the Newton's second law of motion. Due to the AMB inherent uncertainties and to the force coupling present in the proposed prototype, it has been chosen to drive the levitated mass with a H∞ controller. Simulations are run to compare three different H∞ controllers with the quality of the angular velocity measurement as criterion. Finally, a feed forward H∞ controller showed the best performances in terms of angular velocity measurements during simulations run on the prototype developed during this thesis.

EPFL2008