The paper presents a method of structural monitoring with the use of angular displacement measurements performed with inclinometer devices. Inclinometer method is a solution free from the basic disadvantages of optical methods used commonly in structural monitoring, such as sensitivity to any type of visibility restrictions, pollution or influence of weather conditions. At the same time, with appropriate sensor parameters, a much better measurement accuracy is obtained than for typical optical methods and very low energy demand and moderate costs are achieved. Taking into account the above-mentioned issues, in the first stage an appropriate MEMS-type inclinometer sensor was selected, its laboratory tests were carried out and a method of the offset temperature drift correction, individual for each sensor, was developed.

While constructing and documenting civil structures, large machines, and industrial facilities, one can encounter a situation where relevant control points are hardly accessible. The instruments with appropriate surveying equipment available on the market provide relatively standard measurements. The limitations mentioned above may transfer into an increased working time (or financial effort) that must be considered while performing the prescribed measuring works. One of the possible solutions (assuming financial capabilities) is utilizing a video-total station (a scan station) with additional supporting equipment. Another possibility would be employing a terrestrial laser scanner (TLS) or close-range photogrammetry. However, such technologies demonstrate significant limitations, especially in the industrial environment.
Regarding that, the authors propose an original measuring set collaborating with a free electronic total station. The main working principle is a known surveying 3D-polar method that can determine XYZ coordinates. The solution presented in the paper facilitates the performance of inventory works, consisting of dimensioning civil structures and rooms with difficult access. Such situations can often be encountered in industrial plants or while documenting architectural or other engineering structures. The device can also be used for dimensioning ventilation ducts, elevator shafts, and other similar facilities. Depending on the configuration of the measuring equipment and the target shapes, the final accuracy may reach a sub-millimeter or millimeter level. Hence, the solution can successfully be applied in civil engineering, industrial surveying, and industrial metrology.

The paper presents a method of structural monitoring using measurement of vertical displacements realized optically by horizontally directed laser beam. A measuring device with an integrated rangefinder and inclinometer sensor was developed. Inclinometer sensor are used to correct measurement results of the rangefinder in order to eliminate errors resulting from spatial position changes of the laser beam. Such a solution was adopted as an alternative to a more complex and demanding method, which is the stabilization of the laser beam orientation. The proposed inclinometric correction method allows in a simple and clear way to eliminate a serious problem of the displacement measurement method with a perpendicularly directed laser beam, which is inevitable in practice the lack of permanent stability of the measuring device position. The developed measuring device is wireless, both in terms of power supply and communication with other elements of the monitoring system. In order to verify the correctness of measurements carried out by the developed device, on site tests were carried out in two industrial-warehouse buildings with functioning monitoring systems using other measurement methods, earlier verified. The tests confirmed compliance with the indications of the existing system at a level completely sufficient for structural monitoring system purposes. The conducted research show that the proposed method of displacements measurement with inclinometric correction of errors, provides accurate and reliable results, allowing also to obtain additional information about the behaviour of the structure in the place of installation of the measuring device.

The paper presents a method of structural monitoring with the use of angular and linear displacement measurements performed using inclinometer and laser measuring devices. The focus is mainly on the inclinometer measurement method, which is a solution free from the basic disadvantages of optical methods, such as sensitivity to any type of visibility restrictions, pollution or influence of weather conditions. Testing of this method was carried out in practical application in an wireless monitoring system, installed in a large-area industrial building. The measurement results performed using the inclinometers were compared with simultaneous measurements of linear displacements performed with the use of proven methods based on laser rangefinders. The research and analysis show that the method of measuring angular displacements using the inclinometers with MEMS sensors of appropriate quality is a very good, better than typical optical methods, solution of structural monitoring systems that allows to obtain accurate and reliable results.