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Diplomarbeit 2005 (DA05): Arbeits-Archiv
 
DA Hak 05/1 - Algorithm for the detection of impacts
Studierende: Philip Gossweiler, gosswphi
  Dominik Keller, kelledom

Betreuer: Kurt Hauser, husr

Publicly accessible devices are always in danger of being damaged by acts of vandalism. Preventing such damage is usually difficult because it would require better protection of the device or permanent video observation. Such measures usually require substantial financial and personnel expenses. A better approach than ongoing observation is the immediate detection and recognition of occuring damage. In that manner offenders can instantly be caught and not only after time consuming examination of video material. Additionally, this method dramatically reduces the down time of crucial devices because it allows immediate response and necessary repair measures.

As part of this diploma thesis we implemented that method on a information board which is commonly deployed by railway companies at their stations. The mentioned board is vulnernable to impacts because it features a built in liquid crystal display. At the same time it is vital to keep the down time of the information board as low as possible which distinguishs it as an ideal test object. To be able to measure impacts we made use of piezoelectric sensors which generate a signal depending on the amount of force used.

These signals were analyzed and evaluated. With the gained knowledge we developed an algorithm that classifys impacts according to their potential of damage and triggers an alarm if the impact is critical. During the development we tested a wide variety of possible solutions. Under the given circumstances the analysis of the frequency spectrum of the signal has proven to be the most practicable to assess the potential of damage. We implemented the resulting algorithm in a software which is executable on commercial desktop PC running Microsoft Windows. All sensor signals and their interpretation is graphically displayed on the screen.

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