The
DigiClip
system allows the tracking, synchronization and and integrity control
of paper-based documents with their electronic counterparts. Particles
were integrated in a paper clip and allowed to obtain location
information for a document. In conjuction with a document management
system, the DigiClip device enabled a physical notifcation of changes
of the electronic document. The sensors of the DigiClip device allow
further the application of integrity rules on the physical document,
such as document integrity on a single page-level, handling constraints
and location restrictions. The DigiClip device was built by the Adam
Eames who did an internship at SAP in cooperation with TecO.
Features: The DigiClip incorporates a capacitive page-count sensor. Particle XBridges
are used to enable a room-level tracking. Sensors like acceleration
sensor and light sensor are used to detect situation like "put into a
bag", or "put below a bunch of other papers". LEDs on the board
indicate the state changes of the electronic document associated with
the physical one. As a result, the DigiClip system is able to keep electronic and paper-based documents in sync.
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DigiClip on papers | DigiClip close-up |
The DigiClip device is built on top of a Particle core
board utilizing a customized sensor board integrating an acceleration
sensor ADXL210, light sensor TSL250, and a capacitive page count
sensor. Latter is based on a capacitor formed by 2 metal plates wrapped
around the pages of a paper-based document. The distance between the
plates is discriminated by the number of pages in between. We assumed
that equal-thick pages in all our experiments. A DAC on the device
generates a sinoid voltage across the capacitor and an ADC measures it.
The sensor is outlined in the following two figures presenting a
schematic overview and measurement results. A mathematical explaination
is summarized in this document.
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Fig. Page count sensor schematic |
Fig. Measurement results (click to enlarge) |
We also tried out
a force sensor - a flexible resistor, but it turns out, that the
measurements are too instable to achive an acceptable page count
resolution.
In order to track
the DigiClip devices and therefore the documents, we deployed a
cell-of-origin location system using the Particle XBridges. The
following figures depict the overall system.
The DigiClip device is integrated in a document management system. The
database holds the actual state of physical document. The actual state
is sensed and communicated by the DigiClip device attached to the
document via bridges which span a communication cell. The user
configures the DigiClip and receives changes of states, e.g. position
change or alerts.
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Fig. DigiClip System overview (click to enlarge) |
Fig. DigiClip location system |
The DigiClip
device went under a redesign to account for usability and easy
deployment in various scenarios. As a result it became a handy device
which is packed in a plastic box, LED positions were standardized and a
button was added. The DigiClip 2 integrates a variety of sensors, such
as temperature, light, acceleration, microphone. It can be easily
augment by further actuators like speaker and provides a 8 pin
interface for further connections. Although it lost the page count
sensor, DigiClip 2 quickly became a platform for investigating SAP's
Smart-Item scenarios. Such scenarios incoporate physical entities which
are augmented by electronic devices such as the DigiClip in order to
execute business logic at the point of action. We explore such
scenarios in the CoBIs
project. A DigiClip variation was the BlueClip - a bluetooth enabled
DigiClip in the same housing and sensors. It utilizes a zeevo module
for bluetooth communication. Remarkable is the energy consumption which
required an additional battery compared to regular Particle Computer
technology. The blueclip was build to enable the integration of
standard consumer electronics in DigiClip networks. We realized an
authenticated document signature using a regular cell phone as a proof
of concept. A connector board enabled bridging between the two
platforms and communication standards. Download an animation of the DigiClip/BlueClip.
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Fig. DigiClip 2 |
Fig. DigiClip and BlueClip |
Recently, the location system based on DigiClip was improved. Instead of using RF in the cell-of-origin system, we incorporate an IR beaconing system. The beacons were generated by a separate transmitter. The DigiClip's 8 pin port was used to connect a TSOP IR receiver. This allows accurate readings in situations where unreliable RF communication is expected, e.g. industrial areas. Surrounding light was filtered out by software.
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Fig. DigiClip and TSOP receiver |
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The DigiClip was presented in papers on IWSAWC 2004 and Pervasive 2004. Apart from scientific publications, the DigiClip attracted a lot of publicity. It was presented on CeBIT 2004 to the German chancellor Gerhard Schröder and on SAPPHIRE 2004,SAP Research Labs, Palo Alto, SAPPHIRE Australia, "Tag der Informatik" at the University of Darmstadt, Multimedia Forum at the University of Karlsruhe . Articles in SAP magazines utilized the DigiClip to push the idea of Smart-Items in business processes. As a result, the DigiClip is used in scenarios of the CoBIs project implementing collaborative business processes in safety scenarios of BP involving chemical drums.
