Adaptive, contactless near-infrared-sensor-systems for protective devices at saws

Status:

completed 12/2011

Aims:

The goal of the project "Adaptive, contact-free infrared sensor system for protective means at saws" LBIS was the conceptual design, development and practical evaluation of a novel sensor technology which allows a fast, reliable and contact-free detection of hands at saws (and other manually-fed machinery). Such a technology could help to prevent a lot of accidents at such machines, which are generally prone to accidents. In consequence, the labor conditions of many people can be improved and costs for medical treatments, and accident annuities forthe social accident insurance can be reduced. The research was focused on bone bandsaws and circular bench saws for construction sites.

Activities/Methods:

The basic idea of the technology came up beforehand and patents have been applied by the IFA together with the Bonn-Rhine-Sieg University of Applied Sciences (EP2054193 / EP2193878). The technology consists of an optoelectronic sensor system which generates short strobe pulses of near- infrared radiation and receives any reflected radiation by the use of photodiodes. As the system uses LEDs of different peak-wavelengths, the system is able to perform a multispectral scan.

During the conceptual phase, a comprehensive measurement campaign was carried out in which 329 people were examined using spectrometers for the visible and near-infrared spectrum. Additionally, typical workpieces, including 76 samples of wood and 20 samples of meat, have been examined.

The acquired data was analyzed using a custom data-mining software in order to identify an ideal combination of wavebands for the targeted applications. It must be mentioned that the wavebands were chosen in consideration of the LEDs available on the market, as the development of custom LEDs would have exceeded the project's budget.

Results:

During the construction phase, a concept for the setup of the transmitter and receiver was developed together with the company Jenoptik. Optoelectronic and mechanic components have as well been crafted by Jenoptik. The entire development and implementation of embedded electronics and software was done at the Bonn-Rhine-Sieg University of Applied Sciences.

Methods for the calibration and acquisition of learning data were developed to put the functional models into operation. A motorized linear positioning unit was used to perform measurements of a number of objects from different, well-defined distances.

Finally, tests at band saws for metal and bones, as well as circular saws for construction sites were performed under realistic conditions. The results can now be used to develop sample devices. This could be done in cooperation with our industrial partners SIRMAN and AVOLA, which already were involved in the project.

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