Why do we need satellite navigation? In our everyday life we use satellite navigation to locate and navigate our way from one place to another without getting lost. We do not flip a map open anymore but listen instead to a friendly voice pointing us electronically controlled the correct route. But not only automobile manufacturers have started to make satellite navigation exceptionally attractive. Generally, satellite navigation is a key element in a multitude of further outdoor applications. However, it also occurs in indoor technologies, providing an independent positioning, as in the field of logistics, security and mass market. There exists the potential to enter a new market with some applications such as locating of vehicles in tunnels, individual monitoring, electronic museum guide, baggage cart management and secured supply chains in interior buildings.For the tracing of convenience goods the locating with the help of satellite navigation comes into consideration, presently with the US military systems GPS and in the future with Galileo. Nevertheless, these location methods reach their limits in the inside of buildings and in their direct environment. Due to shadowing effects the reception of navigation signals is constrained or even impossible. In this context, for indoor locating, complementary technologies promise higher system availability and locating accuracy. An appropriate combination of such locating technologies enables in this context an opening up for the development of new applications and markets. In particular, in the field of logistics the user expects smooth intersections and technology comprehensive approaches supporting logistic processes and comprising them.
A network of numerous research institutions and industrial establishments has come together in order to intensely investigate diverse technologies for locating the inside of buildings and their environments. Based on a market analysis and the determination of user requirements, an assortment of technologies as well as a first system draft using the combination of suitable operations was carried out. For a multitude of logistic applications one locating system is not sufficient since diverse areas need to be covered such as route of transport, factory premises and storage buildings. On the contrary to a single system that reaches by itself its limits, a combined utilization of various technologies turns out to be reasonable. This aspect attracts special attention for the here presented GNSS-INDOOR research project.
In this connection, the system combines next to locating technologies also communication elements and supporting methods as for instance the utilization of digital map materials for the enhancement of accuracy. Fig. 1 presents several components according to these certain aspects: locating technologies, supporting systems and communication. The criterions for the selection process are accuracy, reach, coverage, availability and infrastructure requirements.
Figure 1: Selection of technologies
Particular components and procedures are well-directed adjusted and expanded. The system is supplemented by sensors for the equipment condition monitoring of transported goods with regard to several factors, among others temperature and pressure. These data are either broadcasted directly through radio communication or by means of web-based interfaces to a server. Thereby, together with the actual position location, further meaningful information content is generated. This information enables an optimization of a logistic process and is useful in form of both, process monitoring and process control. Thereby, an early identification of failures in the process flow leads to cost savings.
3. System Design
The data acquisition during this process is carried out through INDOOR mobile devices and sensors on site. In Fig. 2, each step of the demonstration event is displayed schematically. The end device features diverse extensions and sensors, such as GPS, WLAN as well as further end devices like status sensors and the RFID glove. The sensors serve as status inspection of the locating container. The gathered data run together to a locating server that processes these raw data and performs a location determination. Thereby, several sensor data are taken into account and the best locating result is filtered out. An optimization of results is provided through map matching and video analysis. The reference locating data are continuously transferred to the application server, where the process logic is implemented. There, the logic operation of the gained data is carried out in form of a work flow. The allocation of position and time information for a certain container, the connection and disconnection of tugs (towing vehicles) with dollies and containers, the verification of freight lists, delays as well as the correct delivery of containers to the scheduled loading zones are carried out for instance. Hence, the goal of the developed system is the monitoring and subsequent optimization of logistic processes. One method is a graphic visualization as shown in Fig. 2.
Figure 2: Simplified illustration of the complete system
First experimental investigations were performed in the Radio Frequency Identification (RFID) and Telemetric laboratory “LogMotionLab” of the Fraunhofer Institute in Magdeburg (IFF) focusing on the effectiveness of the chosen technologies under laboratory environment. They were accompanied by a field trial at the DHL Hub of the Leipzig/Halle Airport. In this regard, in collaboration with DHL Hub Leipzig GmbH, one of the numerous towing vehicles that transports airfreight containers from one storage building to predetermined loading zones in the airport apron was equipped with a mobile tracking system. Figure 3 illustrates this previously described scenario at the airport apron.
Figure 3: Towing vehicle with tracking system and airfreight containers at the airport apron (Photograph: Dirk Mahler/ Fraunhofer IFF)
The tracking system combines in this concrete case primarily the utilization of GPS with WLAN as locating technologies whereas the airfreight containers are identified by means of passive RFID technology during loading and unloading procedure, as shown in Fig. 4.
Figure 4: Identification of the loaded airfreight container using RFID-Glove technology provided by Fraunhofer IFF (Photograph: Dirk Mahler/ Fraunhofer IFF)
Supportively, additional methods of video analysis came into operation in order to identify on the one hand frequently navigated routes at the apron and contrariwise to enable an intersection with digital maps. The locating system had the ability to track the transport from and to the loading zone through the airport apron consistently with satisfactory accuracy, supplemented by information regarding the payload status. Furthermore, the process flow was successfully monitored and possible failures such as the unloading in an incorrect loading zone were identified in real-time, see Fig. 5. Due to this operation, the verification of suitability of the developed locating system for process monitoring and process optimization succeeded in a real business environment, under realistic conditions and within the framework of an already existing logistic process.
Figure 5: Schematic demonstration of a real-time process flow (Photograph: Dirk Mahler/ Fraunhofer IFF, Source: Deutsche Post)
Based on a market analysis and the documentation of user demands for an indoor locating system, a deduction of system requirements is carried out. This paper presents the combined application of GNSS-INDOOR technologies for a seamless indoor/outdoor navigation. The technology selection and system design has led to a combination of suitable technologies. Particular components and procedures are systematically customised and extended. For the equipment condition monitoring, a radio sensor technology is additionally applied. After the performance of laboratory tests that guarantee the simulation of logistic sub-processes, a continuous tracing of goods within a field trial at the DHL Hub of the Leipzig/Halle Airport was successfully realised. GNSS-INDOOR has successfully demonstrated how key-technologies such as RFID, WLAN and GNSS can be applied within a logistics process for real-time monitoring as well as process optimisation.
This work has been performed in the framework of the research grant of Bundesministerium für Wirtschaft und Technologie (BMWi) aided by the German Space Agency Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) (Förderkenn-zeichen 50 NA 0701) within two years. The project has been successfully completed in April 2009. The herein involved project partners were VEGA Deutschland GmbH, OECON GmbH, Fraunhofer-Institut für Fabrikbetrieb und -automatisierung IFF, Scheller Systemtechnik GmbH, the Fried¬rich-Schiller-Universität Jena as well as the Centrum für Satellitennavigation Hessen ce¬sah.
 GNSS-INDOOR – Innovative Technologien und deren demonstration zur Ortung in Gebäuden, O. Kalden, A. Jungstand, F. Zimmermann, Deutscher Luft- und Raumfahrtkongress 2008, Darmstadt