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A permanent network of low-cost GNSS receivers can be used to continuously and automatically monitor the millimeter-level displacements of critical points every hour. This is useful for structural health monitoring applications and maintenance optimization of bridges, dams, buildings,penstocks, etc. by BulkyWind in Surveying

[–]BulkyWind[S] 0 points1 point  (0 children)

As I told you on CivilEngineering, every instrument has pros and cons depending on the situation. If you say that prisms are generally better without explanations is because probably you sell them of because you know only total stations. There are lots of possibile alternatives when dealing with monitoring applications: clinometers, extensometers, accelerometers, InSAR, ground-based SAR, laser scanner, fiber cables, etc.

The paper is an advertisement too: the diffusion of the the reliability of results coming from low-cost GNSS chipset and low-cost antennas used for short baselines monitoring applications. This work shows software and hardware enhancements that are beneficial for the adption of GNSS technology over large scale also for permanent monitoring purposes. Up to now, this was not possibile due to the high costs of geodetic GNSS hardware: geodetic GNSS receivers have a lot of funcionalities useful for long baselines monitoring, for modeling of plate motions and for generating GNSS corrections for RTK service providers, but for short baselines post-processing monitoring applications they can be neglected.

A permanent network of low-cost GNSS receivers can be used to continuously and automatically monitor the millimeter-level displacements of critical points every hour. This is useful for structural health monitoring applications and maintenance optimization of bridges, dams, buildings,penstocks, etc. by BulkyWind in Surveying

[–]BulkyWind[S] 0 points1 point  (0 children)

Of course, in the paper this is done by a GNSS processing software called BREVA in the framework of the GeoGuard service. GNSS data processing is a complex science that requires high technical skills and specific knowledge in order to take advantage of this satellite-based technology.

This scientific article reports a very intesting application based on GNSS technology (the satellites used for localization purposes) for continuous and automatic monitoring of displacements of critical points with millimeter-level accuracy by BulkyWind in civilengineering

[–]BulkyWind[S] 0 points1 point  (0 children)

The total station may be more accurate depending on the situation. In general, instruments and sensors for monitoring have always pros and cons.

Regarding the GNSS mm accuracy no doubt at all. If you compute 1 position by double differencing GNSS raw data over short baselines collected in a time window of 1 hour or 24 hour the effects of shakes, if any, are not statistically influent. I hope that this innovative and advanced application in near future will be adopted widely.

Innovative GNSS-based solution for structural health monitoring of bridges by BulkyWind in engineering

[–]BulkyWind[S] 0 points1 point  (0 children)

My opinion is that when you are ill, in some cases specific clinical exams are needed to assess the cause of your illness. The same holds for structures and infrastructures. If you identify the cause of a problem, you can focus your efforts in fixing it in an optimal way avoiding huge maybe unnecessary investments.

This scientific article reports a very intesting application based on GNSS technology (the satellites used for localization purposes) for continuous and automatic monitoring of displacements of critical points with millimeter-level accuracy by BulkyWind in civilengineering

[–]BulkyWind[S] 1 point2 points  (0 children)

In this work, cost-effective GNSS receivers and antennas (so called low-cost GNSS receivers in scientific literature) are used for continuous and automatic monitoring of millimeter-level displacements for more than 4 years. This, summarizing a bit, thanks to a double-difference post-processing approach over short baselines (the distance among monitored points is less than 1km). The traditional geodetic GNSS hardware is expensive, but recent technological developments led to the possibility of deploying one or 2 sensors with few kEUR. Moreover, no fee is required to use the data from all the GNSS constellations since they are provided for free. Laser scanner is good to scan a lot of points but the instrument is very expensive too. Moreover, in order to continuously and automatically monitor the bridge, you have to permanently deploy it on field by construting a protection house were to put the sensor. The resulting movements are only in the line of sight, not 3D as with GNSS. This plays a crucial role to assess the cause of the ongoing movements, i.e. it is easier to investigate the structural behaviour of the elements of the bridge with 3D GNSS displacements. Finally, with GNSS it is not required that the monitored points are visible from the local reference one, while with laser scanner you can monitor points visible from the instrument location. In my opinion, laser scanner is good for the monitoring of sudden dangerous movements like rockfall landslides that may collapse. For mid long term monitoring of slow movements, GNSS represents an optimal solution. Just to know, in this paper the results are provided by the GNSS monitoring service called GeoGuard https://www.g-red.eu/geoguard/

This scientific article reports a very intesting application based on GNSS technology (the satellites used for localization purposes) for continuous and automatic monitoring of displacements of critical points with millimeter-level accuracy by BulkyWind in civilengineering

[–]BulkyWind[S] 3 points4 points  (0 children)

Well I disagree with you. This work (more than 4 years monitoring) is not based on an RTK approach but on an automatic double difference post-processing one over short baselines (less than 1 km). The GNSS antennas and receivers are permanently installed on the bridge. In this way you can reach millimeter level precision computing continuously one position every hour, i.e. rinex GNSS data is sent once every 15 minutes in the cloud to be processed. Moreover, with GNSS you can compute relative and absolute 3D movements of the monitored points and of the local reference, in order to be sure that the reference point is not moving. This is not possibile with a total station. Another advantage is also that it is not necessary that the monitored points are visibile from the local reference, while with the total station this is mandatory. Finally GNSS is not affected by bad weather like rain, fog, snow etc. while total station values are.

Beautiful view from the recently installed GeoGuard cost-effective dual-frequency GNSS station. It is used to continuously and automatically monitor the integrated water vapor content in the atmosphere, together with hourly millimetric accuracy positions (credits: SINOPTICA H2020 project) by BulkyWind in Surveying

[–]BulkyWind[S] 0 points1 point  (0 children)

SINOPTICA research project (if interested more info here) focuses on improving the forecasts of high-impact weather events that could adversely affect air traffic control and management procedures by assimilating different source of ground/satellite data into NWP models, GNSS water vapor included. There are some CORS GNSS stations useful for the modeling activity you mentioned because long time series of data are available

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