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Workflow Integration of Physical Goods | ||||
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Download a zipped Postscript Version of my master thesis here (1.5MB) | ||||
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In today's industry many goods are transported between producer and consumer by many different transportation media. Often sensitive goods have special requirements that have to be fullfilled not only during stockage but also during transportation from one stock to another. In our concrete case we have photo chemicals that need to be kept in a certain temperature range in order not to lose their specific chemical characteristics. In order to asure that the delivered goods are in good condition temperature has to be recorded during all transportation process. | ||||
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Nowadays it is up to the producer or deliverer to provide for a means of control of the goods.
These means are often not sufficiently reliable for consumers as corrupted goods may damage
a whole production chain. For example, very often analogous thermometers are attached to the
goods which are able to show the maximum and minimum temperature. These are often big and
badly attached as to fell off the goods and therefore measuring not the exact temperatures.
Also truck drivers do not know about these thermometers, find them rolling around in their
truck and just throw them away so that no measurements at all are available.
The analogous devices are also not very accurate and also do not show the period during which a certain temperature was reached. Maybe the maximum temperature was reached only during a few minutes and did not damage the goods which however have to be discarded anyway because the time information is not available. |
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The requirements for a new solution were that it had to
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Choice of the adequate measuring device is one of the most important parts of the project.
The best one we found is the Minidan, produced by ESYS GmbH in Berlin. The Minidan is a digital data logger available for temperature as well as for other parameters as humidity, acceleration, orientation, voltage and movements and vibrations. It can store up to 16,000 values with an accuracy of 0.03°C or alternatively the double amount with an accuracy of 0.5°C. With the high accuracy it thus can measure continuously for 166 days or 5.5 months at a measure rate of 15 minutes.The Minidan is equiped with an infrared interface for wireless communication with the PC. It can alternatively be built also with radio frequency interface. Radio frequency has the advantage that it does not require intervisibility but, on the other hand, may be disturbed when operating in a metallic environment. The PC can manage up to 5 Minidans simultaneously. The battery lasts for 2 years minimum at a medium measuring and communication activity. There is no indication about the remaining power but changing the battery every 2 years when calibrating the thermometer seems a practical solution as well. A new version of the Minidan is able to store event timestamps additionally to temperature data. A timestamp is recorded each time the logger is read together with an id specific to the reading person or device. This allows for maximum control over the data and events during transportation. The logger can be readout during transportation for intermediate control (goods can be sent back to the producer if found defective already on the way). |
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There is several pieces of software needed for the project:
If the starting time cannot be determined at the point of the parameterization the cube has to be started right after the goods leave the depot, being already attached to them. For this case a small device can be constructed with infrared interface that does nothing but sending the starting signal to the Minidan. The second and the third piece constitute the main part of the project. The architecture is chosen in order to have the software work for both of these cases. Have a look at an overview over the architecture in the slides. The program consists of two parts. The first reads the data from the cube via an infrared interface and then stores the data in XML format in a file. The second part has to communicate with a backend system's interface to transfer the data. It consists of a http server and client. The client connects to the backend system's interface, which in our case is the SAP Business Connector, and notifies it to read in a new XML data file. The web server has two tasks. The first is to hand the XML file to the backend system, the second is user interface communication. The user interface is entirely working in a web browser and therefore is independent of the operating system. Also the program can be managed remotely which is important to enable a quality manager in another department to take care of errors rather than leaving this difficult task to the workers down in the discharging area. The HTTP/XML interfaces between the program and the backend system as well as the user interface make the program very flexible and easy to adapt to other systems and environments. It also allows for easy deconnection of the first from the second part in order to use the first part for intermediate readout. The XML data can then be viewed directly in a browser together with an XSL style sheet instead of being transferred into a backend system. The programming language is Ansi C++ which is also sufficiently independent of platforms and offers all necessary functionality for infrared communication. The project is developped on Windows NT but should be portable for use on Unix operating systems as well. |
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The development is finished and the software has been installed on the corresponding pilot systems. The pilot consumer is Infineon Technologies AG, Dresden, and the producer is Shipley, Amsterdam. During this phase, the project will be used to gain further insight into the problem and first experiences with the system. Both sides are very optimistical about the usability and the advantages of the system. | ||||
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We appreciate very much any kind of comment on the project or these pages. Do not hesitate to write an e-mail to anke@thede.net. |