Application Platform Intelligent Mobility - Test Site Architecture and Vehicle2X Communication Setup

Transcription

1 Application Platform Intelligent Mobility - Test Site Architecture and Vehicle2X Communication Setup Tobias Frankiewicz, Lars Schnieder, Frank Köster German Aerospace Center (DLR) Institute of Transportation Systems Lilienthalplatz 7, D Braunschweig, Germany Tel.: , Fax: {tobias.frankiewicz, lars.schnieder, frank.koester}@dlr.de Keywords Vehicle2X-Communication, V2X, Cooperative Driver Assistance Systems, Test and Validation, Application platform for Intelligent Mobiliy 1 Abstract The German Aerospace Center is currently constructing a large-scale research facility called Application platform for Intelligent Mobility (AIM) [1]. This paper describes the reference track a test site for Vehicle2X communication and cooperative driver assistance systems as a major part of the new research infrastructure [2]. After the hardware architecture is discussed in detail, use cases and related research projects using the infrastructure are briefly described. 2 Introduction and Motivation With its Application Platform Intelligent Mobility (AIM) [3], the German Aerospace Center (DLR), the state of Lower Saxony, the city of Braunschweig and other partners, are creating a unique way of linking up research, development and applications for intelligent transportation and mobility services. As a major system for research, AIM enables users from science, research and development, and industry to study a wide range of topics from the highly complex, interlinked world of transportation. AIM integrates and draws on the actual traffic and transportation environment in the city and region of Braunschweig and includes special test tracks as well as a powerful set of instruments to simulate large-scale and microscopic aspects of mobility. As an open and flexible research platform, AIM has been designed with longevity and sustainability in mind. Unlike previous approaches involving individual, topic-based test sites in different cities, AIM allows the test infrastructure to be reused to address a wide range of challenges. AIM therefore considerably reduces the investment requirement for each project. The basic infrastructure can be reused in a variety of projects and modified to accommodate 1

2 particular needs. AIM also makes it possible, at relatively little expense, to handle long-term data and studies that extend well beyond the typical term of individual projects (two to three years) and to ensure that the infrastructure and results can be reused. An important part of this new research facility is a reference track on a public road around the city center which will be equipped with so-called ITS Roadside stations (IRS) for Vehicle-to-X communication (V2X). Details of this reference track, especially the IRS communication architecture will be discussed in this paper. 3 Reference Track 3.1 Hardware Setup of an AIM ITS Roadside Station Figure 1 shows the hardware setup of an AIM ITS Roadside Station (IRS). Each IRS consists of the following components: a Communication Control Unit (CCU), a specialized communication device for V2X communication according to IEEE p an Application Unit (AU), a computer to process applications requiring a higher computing capacity in the field. Furthermore a database can store process data (e.g. sensor input). a GPS receiver for both time and positioning reference an interface to the adjacent traffic light controller a connection to the backbone network 1 Additionally, a specific IRS can be equipped with one or more of the following components (dotted line in fig. 1): a connection to the traffic tower (e.g. via ethernet) further communication modules such as regular Wireless LAN (WLAN) sensors for traffic detection such as radar sensors or cameras Modularity has been a major paradigm in the development of the IRS architecture. Inside the IRS the different components are interlinked by ethernet LAN. This means that any component could be easily replaced by another one (e.g. with higher performance or from a different manufacturer) and new components can also be easily integrated. Because of this modular architecture the same setup of AU, CCU, GPS receiver and additional sensors is also used inside the vehicle as an ITS Vehicle Station (IVS). Then, the traffic light interface is replaced by a vehicle interface to access the vehicle systems. 1 This connection is realized by an internet connection (via UMTS or SDSL) and a VPN tunnel 2

3 Sensor WLAN V2X GPS AU Traffic light interface CCU backbone network connection to traffic tower Figure 1: ITS Roadside Station: hardware setup The Communication Control Unit (CCU) is a device that handles the Vehicle2X communication. It periodically sends beacon frames on the V2X band and it transmits messages whenever requested by the Application Unit (AU). Any application-specific software runs on the AU, which is an industrial-type computer with some hardware modifications (smaller size and wider temperature range). In the current setup, the AU software receives signal state 2 messages that are sent by the traffic light interface on a UDP port and forwards these messages to the CCU without changing them. In future applications the AU will compose new messages on demand and send them to the CCU for transmitting via V2X. The GPS receiver is used to add accurate time stamps to the V2X messages. Since the IRS is stationary the precisely 3 measured position is stored inside the CCU and transmitted with every beacon frame. In order to get information from the traffic light controller, each IRS has a specialized interface that allows a read-only 4 communication between the traffic light controller and the AU. Both the traffic light controller and the interface were developed by Siemens in order to guarantee safe operation of the traffic light system. The backbone network connects the IRS with each other and with the ITS Central Station, a backend server which is currently being specified. There are three feasible ways to connect the IRS to the backbone: a UMTS mobile radio connection, a regular Wireless LAN or an SDSL 5 connection. At the moment, all IRS are connected via UMTS. At selected locations a regualar 2 The signal state message is defined in the sim T D project [4]. 3 The IRS positions are measured with a differential GPS system. The position accuracy is better than 0.5 m. 4 Currently, the ISR only receives information from the traffic light controller. An interaction with the traffic light controller is currently being developed to enable prioritzation of certain vehicles. 5 Symmetric Digital Subscriber Line 3

4 SDSL internet connection will be installed. In both cases a VPN 6 network is used to ensure connection security. The other IRS locations will be connected via a regular Wireless LAN which serves two purposes: interlinking IRS that do not have an own uplink to the backbone network and providing information to mobile devices of road users and non-road users via IEEE g. A special WLAN network is being installed that uses mesh technology to realize this task. A mesh network provides roaming between the various WLAN access point, so a mobile device can move inside the mesh network without loosing connection to the network. Furthermore, several VLANs 7 are provided on the wireless network to devide and secure the different services that are offered. 3.2 Geographical Scope In general the V2X reference track follows the ring road around the city centre of Braunschweig (see figure 2). This part of the city is an optimum setting for research directed to the improvement of urban road traffic (e.g. optimization of traffic flow and efficiency). Traffic density is highest in this part of the road network as well as related emission of noise and air pollutants (CO 2, NO x and PM10). The chosen section of the road network covers many interesting aspects of traffic management including prioritization of public transportation vehicles and emergency vehicles, audible signals for visually impaired or blind persons as well as a variety of existing sensors (e.g. cameras or inductive sensors). Figure 2 shows a map of Braunschweig s city center. The V2X system is operational at the first three intersections since July 2011 (top right corner of fig. 2). Since then first applications were demonstrated in the field (e.g. traffic light assistance, see section 4.1). In 2012 further eleven intersections were added (purple dots). Ten more IRS will be installed until the end of In 2013 the test site will be further extended (dotted lines). The geographical scope will primarily be driven by the requirements of upcoming research projects. 6 Virtual Private Network 7 Virtual LANs allow several logically seperated LAN connections on a single physical link. 4

5 Figure 2: AIM Reference Track purple dot IRS operational (08/2012) red dot IRS to be installed in 2012 dotted line Possible extensions in Applications and Use Cases 4.1 DLR Traffic Light Assistance An IRS is able to communicate the current state of an adjacent traffic light and further information (e.g. topology of data) to road users via a wireless ad-hoc network according to the IEEE p communication standard. Furthermore regular Wireless LAN is added in order to distribute at least the same data to other road users and non-road users (e.g. cyclists and pedestrians). These information is currently received by the research vehicle FASCar that runs a traffic light assistance algorithm developed by DLR. The FASCar is a reseach vehicle that was developed for the implementation and test of Advanced Driver Assistance Systems with a focus on highly automated driving. In the past two years the vehicle was also equipped with a Vehicle2X communication system and a computer display which is located in front of the steering wheel (at the speedometer s position of regular vehicles). Figure 3(a) shows a picture of the research vehicle. In fig. 3(b) the display of the Traffic Light Assistant (TLA) is shown. The TLA uses the vehicle s GPS position and information on the traffic light s signal state that is received via V2X communication. A model of the vehicle s acceleration behaviour is also integrated in the TLA algorithm. Based upon this data and the known position of the stop line at the intersection a speed advice is calculaed as an interval of a minimum speed and maximum speed. The display shows the current phase of the traffic light and the suggested speed interval on the speedometer (green circular segment) if it is possible to pass the traffic light in a green phase. If a stop is unavoidable an engine off advice is shown on the display. In the near future this application will be further improved. Future research will be directed 5

6 towards the valid prediction of green times especially for traffic-actuated traffic lights as well as the improvement of available data for queue-length before the stopping line. (a) DLR Research Vehicle FASCar (b) Display of the Traffic Light Assistant Figure 3: DLR research vehicle FASCar 4.2 Related research projects The installed infrastructure of the AIM reference track is also used in various research projects. This section briefly describes two examples of those. KOLINE [5] is a national research project founded by the German Federal Ministry of Economics and Technology. It aims on improving the traffic flow and traffic efficiency on a road network by measuring of traffic data and online optimizing the phases of traffic lights in the whole road network. The project s final demonstration will take place in 2012 both on a non-public test site and in the city of Braunschweig using the AIM infrastructure. In order to realize the test case several radar sensors will be installed on three intersections within the reference track. A server working as ITS Central Station processes the measurement data and calculates an optimized signalization scheme which is transmittet to the traffic tower of the infrastructure operators. The research project Stadtpilot [6] [7] is run by the Braunschweig Technical University and focuses on autonomous driving on a public road in the city of Braunschweig. A V2X communication unit has been integrated into the project s research vehicle which enables it to receive the current traffic light s signaling states. The artificial intelligence can then react on this information, optimizing the vehicle s speed or stopping at the stop line if neccessary. 6

7 5 Outlook As stated in the previous section, several current and future reseach projects can use the infrastructure of the AIM reference track in order to concentrate on their own research questions without having to install an own test site for each project. Furthermore time and budget can be saved by simply adding some project-specific extensions to the existing AIM infrastructure. In the future the currently existing uni-directional interface between the traffic light controller and the IRS will be extended to cover bi-directional interaction. Other use cases (e.g. prioritization of public transportation vehicles) will become possible. The AIM test site infrastructure will continously grow until its planned size is reached at the end of While extending the test field by installing more IRS at the planned locations and adding other components the infrastructure will also be extended according to the needs of other related research projects which are driven by the DLR, e.g. integrating traffic sensors. In parallel to the expansion of the infrastructure a fleet of vehicles (including buses) will be equipped with V2X communication equipment to perform field operational tests. This way the large-scale research facility AIM will significally improve the research landscape. Acknowledgement The DLR thanks the state of Lower Saxony, Germany and the Helmholtz Association of Research for founding the AIM project with an overall budget of 15 Million Euro. References [1] Frank Köster, Marco Hannibal, Tobias Frankiewicz, Karsten Lemmer. Anwendungsplattform Intelligente Mobilität Dienstespektrum und Architektur. In AAET: Automatisierungssysteme, Assistenzsysteme und eingebettete Systeme für Transportmittel, volume 12. ITS Niedersachsen, Intelligente Transportsysteme und -dienste Niedersachsen e.v., [2] Tobias Frankiewicz, Arno Hinsberger et. al. Standortbestimmung und Integration von ITS Roadside Stations für die Anwendungsplattform Intelligente Mobilität. In AAET: Automatisierungssysteme, Assistenzsysteme und eingebettete Systeme für Transportmittel, volume 12, pages ITS Niedersachsen, Intelligente Transportsysteme und -dienste Niedersachsen e.v.,

8 [3] German Aerospace Center, Institute of Transportation Systems. Application Platform for Intelligent Mobility. January [4] simtd project consortium. Deliverable D Spezifikation der Kommunikationsprotokolle. [5] Bley, Kutzner, Friedrich, et al. Kooperative Optimierung von Lichtsignalsteuerung und Fahrzeugführung. In AAET: Automatisierungssysteme, Assistenzsysteme und eingebettete Systeme für Transportmittel, volume 12. ITS Niedersachsen, Intelligente Transportsysteme und -dienste Niedersachsen e.v., [6] Tobias Nothdurft, Peter Hecker, Sebastian Ohl, Falko Saust, Markus Maurer, Andreas Reschka, Jürgen Rüdiger Böhmer. Stadtpilot: First fully autonomous test drives in urban traffic. In 14th International IEEE Annual Conference on Intelligent Transportation Systems, pages , [7] Tobias Nothdurft, Peter Hecker, Tobias Frankiewicz, Jan Gacnik, Frank Köster. Reliable information aggregation and exchange for autonomous vehicles. In IEEE 74th Vehicular Technology Conference: VTC2011-Fall,