CALIBRATION OF MAGNETIC FIELD SENSOR USED FOR DIAGNOSIS OF STEEL CONSTRUCTION

Przemysław Szulim – Szymon Gontarz – Jędrzej Mączak

   We present the results of an investigation into the calibration of a few types of magnetic sensors. This work focused on the diagnosis of large-scale steel construction based on the concept of a passive magnetic field observer. This relatively new meth-od uses observed variations in the magnetic field around steel construction. Due to magneto-mechanical phenomena, the condi-tion of construction material can be estimated and a prognosis of its state of health can be made. To achieve this aim, in addi-tion to an algorithm, one requires a network of magnetic sensors placed near responsive locations in a construction site. These sensors characterize the sensitivity of the magnetic field at the level of the Earth's magnetic field. Considering the long duration of on-line monitoring, the invariability of the sensor parameters becomes an important feature. Magneto-resistive sensors, MR or GMR, and fluxgate type magnetometers were examined. Temperature stability of the sensors appears to play a key role. Both the sensitivity and the sensor offset temperature drift are involved during measurement. To calibrate the temperature, a set of three-axial magneto-resistive sensors was placed in a climatic chamber. In this paper the experiment results are described and a calibration method is proposed. As an example, measurements are presented from a large steel hall under laboratory and real world conditions

Keywords: magnetic field, sensor calibration, temperature influence

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