Global Navigation Satellite System is considered as the only reliable source of offering positioning information in the time systems and global references. These features are important for ensuring some consistency in the information acquired at monitoring stations. A variometric approach termed as VADASE has been implemented to provide real-time displacement and velocity estimates from dual and single frequency stand-alone receivers.
Although the geodetic dual frequency Global Positioning System receiver has been implemented in experiments, it has been found that such dual frequency receivers and low-cost single frequency ones, function in a similar fashion when it comes to velocity approximation with VADASE as well as standard methods. Therefore, the outcomes can be extended to any GPS receiver whether dual or single frequency.
Global Navigation Satellite System suffers some setbacks. These include, noise, sky visibility observable correlation, and limited frequency acquisition, and this may be compensated by accelerometer sensors capability. Therefore, low-cost Micro Electro-Mechanical System accelerometers appear to be a potential alternative to the high-cost accelerometer sensors, which have been so far adopted for monitoring applications.
When it comes to Global positioning system and Micro Electro-Mechanical System integration the Global Navigation Satellite System offers displacements as well as velocities in a global reference time. On the other hand, Micro Electro-Mechanical System offers accelerations in a sensor-fixed system that may have some variation because of movements of the monitored object. Elisa Benedetti and Mattia Crespi at University of Rome ‘‘La Sapienza” and in collaboration with Athanasios Dermanis at the Aristotle University of Thessaloniki investigated the feasibility of integrating the benefits of Micro Electro-Mechanical System accelerometers and Global Navigation Satellite Systems with an eye on the low-cost Global Navigation Satellite System receivers, in a bid to enhance the diffusion of low-cost monitoring. Their work is now published in Advances in Space Research.
The authors set up the merging methodology at the level of combination of kinematics results i.e. displacements and velocities generated from two sensors, where the observations were processed separately. Global Positioning System results were processed implementing the VADASE and its improved version approach in a bid to obtain velocities and displacements respectively. Micro Electro-Mechanical System results i.e. accelerations, were integrated numerically to get displacements and velocities as well.
Difference in reference and time systems, measurement rate and epochs for the two sensors were a few issues faced with when trying to combine the kinematic results. Therefore, the authors developed and tested an approach that was helpful in transforming into a unique reference and time system the results from the Micro Electro-Mechanical System and Global Positioning System. However, the method was limited to time-dependent arrangement of the Micro Electro-Mechanical System with respect to the GPS.
The authors then proposed a data fusion method pegged on Discrete Fourier Transformation and cubic splines interpolation for displacements as well as velocities. The derived solutions of Micro Electro-Mechanical System and Global Positioning System were initially separated by a rectangular filter in spectral domain, and then combined via a cubic spline interpolation.
The method was applied to experimental results and accuracies of about 5 mm for booth slow and fast displacements and 2mm/s for velocities were evaluated. The outcomes give way to an appealing and powerful implementation of low-cost single frequency receivers necessary for monitoring. The use of Micro Electro-Mechanical System- accelerometers present a powerful tool for enhancing Global Navigation Satellite System potentials for structural as well as ground investigations and monitoring.
Elisa Benedetti, Athanasios Dermanis, and Mattia Crespi. On the feasibility to integrate low-cost MEMS accelerometers and GNSS receivers. Advances in Space Research, volume 59 (2017), pages 2764–2778.Go To Advances in Space Research
Benedetti, E., Branzanti, M., Biagi, L., Colosimo, G., Mazzoni, A., Crespi, M., 2014a. GNSS seismology for the 2012 Mw = 6.1 Emilia earthquake: exploiting the VADASE algorithm. Seismol. Res. Lett. 85 (i. 3), 649–656.
Benedetti, E., Branzanti, M., Colosimo, G., Mazzoni, A., Crespi, M., 2014b. Integration of low-cost GPS receivers and MEMS-accelerometers: experiments and potentiality of a new approach for real-time structural monitoring. In: ENC – GNSS 2014 Proceedings (Session D5) (online only).
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