assets as one promising field of application for WSN. In particular we show .... application platform for diverse smart object technologies like. RFID, RTLS and ...
Wireless Sensor Network-Based Asset Management for Mobile Measurement Devices Helena Preiß, Sebastian Lempert, Christopher Kaffenberger, Alexander Pflaum Department for Supply Chain Technologies Center for Intelligent Objects ZIO Fraunhofer Institute for Integrated Circuits IIS Fuerth, Germany Email: {helena.preiss; sebastian.lempert; christopher.kaffenberger; alexander.pflaum}@iis.fraunhofer.de Abstract – The maturity level of Wireless Sensor Networks (WSN) has grown constantly and the market offers first components and products. Nevertheless the commercial breakthrough in industries has not yet happened due to the lack of economically justifiable applications. This paper presents the management of assets as one promising field of application for WSN. In particular we show how the existing asset management process for mobile measurement devices at Fraunhofer IIS is optimized with a WSN-based asset management system.
I.
AN INSUFFICIENT ASSET MANAGEMENT HAS NEGATIVE IMPACTS ON VALUE-ADDING PROCESSES AND FINANCIAL CAPABILITIES
Asset management could be defined “as systematic and coordinated activities and practices through which an organization optimally and sustainably manages its assets and asset systems” [1]. In this context we understand assets as physical goods which are essential for the execution of the value-adding process but don’t merge in the final product. From our point of view the need for an asset management system is reasonable when three circumstances occur: Assets have a high monetary value. Assets have more than one user or responsible person. Assets are critical for the company’s success as the value-adding process depends on them. In many cases a fourth criteria becomes essential as physical assets can be mobile. These assets move around in a company or on a site, are used at different places and often have not a dedicated storage location. If a company has not installed an asset management system the last criteria leads to a lack of transparency about the number, the status and the location of the assets. The assets wander around, nobody feels responsible for them and they finally get lost. Under these conditions a company has to hold high security stocks if it wants to satisfy customer requests in time. This ties up capital and narrows the financial capabilities for the company. Additional, a badly performing asset management influences the value-added processes negatively as assets have long waiting times or are missed completely.
Asset management systems are as various as the companies using them but mostly they don’t meet the high expectations in reducing the stock, speeding up the processes and solving the problems mentioned above. To prevent negative impacts of an insufficient asset management, in this contribution we propose the use of WSN for the management of eligible assets in general. In particular we present a WSN-based asset management solution for mobile measurement devices at Fraunhofer IIS. The rest of this contribution is organized as follows. A comparision between this contribution and related work is given in section II. In section III we describe what the previous asset management process at Fraunhofer IIS looked like in the past along with its weaknesses. On this basis in section IV we present the developed WSN-based asset management system, the benefits that come along with it and the method for optimizing the existing asset management process. We conclude this contribution with a summary and an outlook on prospective future work in section V. II.
STATE OF THE ART: WSN FOR ASSET MANAGEMENT
WSN are broadly discussed in industries and research literature, where [2] and [3] give a good overview about different application areas. Although the maturity level of WSN has grown constantly over the years, a commercial breakthrough has not happened yet. We compared 13 suppliers concerning their offerings in the area of asset management systems and found out that all companies offer RFID-based and about the half WLAN- or RTLS-based solutions. Only one company has WSN in its portfolio what leads us to the assumption that either the customers don’t request this technology or that WSN-based solutions for asset management are not ready for the market. In contrast, a look on the scientific literature reveals first pilot and test applications of WSN for the management of assets. The main application areas are the health care sector and hospitals. For example, in [4] and [5] medical devices are equipped with ZigBee-based WSN nodes in order to track their positions. The WSN consists of 21 mobile nodes and they aim especially on time savings, asset utilization and an efficient inventory management. A similar approach is described in [6]. In a clinical environment a WSN consisting of about 500 mobile s-net sensor nodes is used to optimize asset tracking, the supply chain of blood product and the patient safety during
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blood transfusion. Furthermore, WSN test installations are used for asset management in logistics and supply chain management. For example, commissioning might be improved by using shelves and containers equipped with sensor nodes which are speeding up picking processes [7]. This comparison shows that there is still a discrepancy between research results and their use in the industrial practices. The asset management system presented in this contribution wants to reduce this gap. III.
EXISTING ASSET MANAGEMENT PROCESS FOR MOBILE MEASUREMENT DEVICES AT FRAUNHOFER IIS
A. Identification of Weaknesses in the Existing Process The Fraunhofer Institute for Integrated Circuits IIS makes use of a range of high-priced measurement and testing devices from 1.000 € to 100.000 € used by different organizational teams for research and industry projects. One single measurement setup can consist of numerous devices so that their worth can sum up to 1.000.000 €. The original asset management process was supported by a central IT-system. When new laboratory equipment was bought, it was inventoried with its accompanying information like identification number and type, its supplier, its storage location and the responsible person in a database. All registered employees are able to log in the IT-system, but they are only allowed to search for devices and to change the current asset location. The lending process looks as follows. If a person wants to borrow a measurement device he or she selects it via the IT-system and looks around in the laboratories. If a suitable device is found and moved from one room to another, the employee is urged to update the current location in the ITsystem manually. B. Derivation of Requirements for a Supporting Asset Management System The process described above causes problems and a dissatisfactory asset management situation. The employees don’t consequently update the data in the IT-system and so virtual and real storage locations are not consistent. This leads to a couple of resulting discomforts with the asset management system. To identify and rank the main problems guided interviews consisting of 26 questions were carried out with seven engineers. The seven engineers are responsible for the measurement devices in their departments and spend most of their working time with measurement tasks. A new asset management solution should help to solve the following eight aggregated main problems which negative affect the valueadding processes and the financial capabilities of the company: Long search times for measurements devices as their current location is not valid in the IT-system. Decentralized storage of devices as they are not returned to their original location after usage. Loss of devices as they are borrowed by other departments of the company and are not returned later. High safety stock due to the attempt to satisfy customer requests in time.
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Time delays of research projects as industrial projects are preferred in case of bottlenecks. Measurement installations cannot be reproduced on a later date. Accompanying documents get lost, mixed up, or dirty and so important information are not well attached to the measurement device. Yearly inventory is time consuming as the measurement devices have to be searched and documented manually. Beyond these problems, the seven interview partners mentioned additional functionalities the asset management system should support: Identification of measurement devices on item level. Active localization of measurement devices. Geofencing for the laboratories. Geofencing describes the implementation of virtual fences around an area and the active triggering of alarm messages when a fence is crossed without permission [8, 9]. As the current IT-based asset management system caused dissatisfaction among the employees, could not solve all problems mentioned above and was not able to fulfill the additional requests of the engineers, a new solution had to be found. In this case, a WSN-based solution was selected for two reasons. First, WSN provide all technological functionalities to meet the requirements and second, a cost-benefit analysis shows the best ratio compared with other technologies like RFID or RTLS [10]. IV. OPTIMIZATED ASSET MANAGEMENT PROCESS THAT USES A WSN-BASED ASSET MANAGEMENT SYSTEM A. Overview on the System Architecture The technical implementation relies on an integration and application platform for diverse smart object technologies like RFID, RTLS and WSN. This fundamental architecture unites these technologies with a shared technology abstraction layer, controls the interaction between these technologies and existing enterprise infrastructures, supports intra-corporate and crosscompany integration and aims at reducing integration costs significantly. Furthermore the platform is equipped with a set of basic applications that serve as a basis for the efficient development of more sophisticated applications for the Internet of Things [11]. The essential requirements that such a platform should meet are presented in [12], further detailed requirements and the corresponding fundamental abstract architecture are presented in [13]. In addition a description of the underlying methodological approach that comprises the structured derivation of functional requirements from real world applications and subsequently the design of the platform is given in [10].
sdfsdfadasd Figure 1: Asset management system architecture based on s-net sensor nodes and the integration and application platform
As can be seen in Figure 1 the implemented asset management system architecture consists of:
Java EE components. The same applies to the asset management application on top of the platform.
Mobile and fixed WSN infrastructure: Since mobile sensor nodes are battery powered, frequent battery changes would be a show-stopper in a system with a large amount of deployed sensor nodes. Consequently the system is built upon very energy efficient s-net sensor nodes and corresponding gateways and anchor nodes that were developed at Fraunhofer IIS [14].
B. Details on the Functionalities of the Developed System For every asset, basic information like inventory number, warranty expiration date and specification are stored in a database. These information are accessible via a web frontend, where reservations can be made, capacities can be checked and measurement setups can be defined and reproduced.
Integration and application platform: The platform serves as a basis for the asset management application and connects this application and the WSN infrastructure to the existing enterprise IT. Existing enterprise IT: The asset management system is integrated into the intranet of Fraunhofer IIS. An additional connection to the existing management information system is planned for the near future. Clients: The asset management system comes with a user friendly graphical user interface that can be accessed with usual web browsers. The concrete implementation of the above mentioned abstract platform architecture is based on the current Java EE specification Version 6. Amongst others our implementation leverages the standards EJB 3.1, JPA 2.0 and JSF 2.0 while using JBoss AS 6.0.0, PostgreSQL 9.0.4 and OpenFaces 3.0. The platform modules presented in [13] are implemented as
Since real life information must be available to the system, every asset is equipped with and represented by a s-net sensor node (see Figure 2). Periodically, the sensor node sends its position to the integration and application platform via hard wired anchor nodes (which are installed in almost every room) or directly to the gateway, which routes messages to the platform. After receiving and interpreting a message, the platform maps the sensor node id to the asset id, adds a time stamp and stores the coordinates of the node in a database. Furthermore, the room number that belongs to these coordinates is determined by a positioning engine and stored in the database too. Amongst others, on this basis, two scenarios can occur: Users can ask for the actual position of an asset: that means that via a web frontend the last room that has been determined by the positioning engine is shown on a map.
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The system logic is responsible for generating alert messages in case defined geofences are crossed without permission: every time the server receives the position from a sensor node, the generated room number is compared to a list of rooms an asset must not leave. In case that the room number is not one of those associated with the asset, a SMS message is sent to the owner of the asset. Last but not least the management of the system is done by an authorized administrator, who can add new assets to the system, assign to them their respective sensor nodes, allocate geofences, add new users and administrators and (un-)connect the system to gateway nodes.
adequate level. This will be done through usability tests with a group of users, who answer questionnaires and execute typical use cases with the asset management system. The results of these tests will build the base for the optimization of the system in a version 2.0. In addition in the next months the system will be enlarged: more measurement devices will be tagged with the s-net sensor nodes. Furthermore the next generation of s-net sensor nodes will be developed and used as well. These nodes will be equipped with an energy efficient Wake Up-Receiver [15] that represents a significant contribution to the economy of the WSN-based asset management process. [1]
[2] [3] [4]
[5]
[6] Figure 2: Mobile measurement device observed by s-net sensor node [7]
C. Testbed for the Asset Management Application The project was executed at two distantly located departments of the Fraunhofer Institute for Integrated Circuits IIS, Nuremberg and Fuerth. Every department initially received about 20 sensor nodes. In addition, 30 anchor nodes were permanently installed at both department sites. The asset management system itself is available via a web frontend and thus accessible via the Fraunhofer IIS intranet site. V.
[9]
[10]
CONCLUSION AND OUTLOOK
This contribution was motivated by the negative impacts that an insufficient asset management has on value-adding processes and financial capabilities. Against the background of an inefficient asset management process for mobile measurement devices at Fraunhofer IIS, we showed how this process was optimized with a WSN-based asset management system: we described what the previous asset management process at Fraunhofer IIS looked like in the past along with its weaknesses. On this basis we presented the developed WSNbased asset management system, the benefits that come along with it and the method for optimizing the existing asset management process at Fraunhofer. The system has been implemented over the last months and the next step is the evaluation of the system. Aim is to proof if the system supports the users in the departments on an
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[8]
[11]
[12]
[13]
[14]
[15]
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