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The dynamic performances of an innovative robotic total station (RTS) are assessed while tracking a moving target; also, the results of these performance evaluations are exploited to design its control system. The proposed methodology is novel and uses ad hoc virtual experiments implemented on the digital twin of the studied RTS. This methodology is general and is also applicable for the design of other mechatronic systems. The proposed ad hoc virtual experiments constitute a benchmark for assessing the tracking performances of pointing systems. The application of this methodology to the studied RTS will help complete the RTS's design by determining the most suitable actuators and the control system constants necessary to obtain the assigned dynamic performances. A 3D-printed prototype of the designed RTS was built and is shown in this paper. [ABSTRACT FROM AUTHOR]

Rockfall phenomena are considered highly dangerous due to their rapid evolution and difficult prediction without applying preventive monitoring and mitigation actions. This research investigates a hazardous site in the Municipality of Vecchiano (Province of Pisa, Italy), characterized by vertical rock walls prone to instability due to heavy fracturing and karst phenomena. The presence of anthropical structures and a public road at the bottom of the slopes increases the vulnerability of the site and the site's risk. To create a comprehensive geological model of the area, Unmanned Aircraft System (UAS) photogrammetric surveys were conducted to create a 3D model useful in photointerpretation. In accessible and safe areas for personnel, engineering–geological surveys were carried out to characterize the rock mass and to define the portion of rock walls to be monitored. Results from nine multitemporal Robotic Total Station (RTS) measurement campaigns show that no monitoring prisms recorded significant displacement trends, both on the horizontal and vertical plane and in differential slope distance. Additionally, satellite Persistent Scatterer Interferometry (PSI) analysis indicates that the slopes were stable over the two years of study. The integration of these analysis techniques has proven to be an efficient solution for assessing slope stability in this specific rockfall-prone area. [ABSTRACT FROM AUTHOR]

The development of multi-sensor systems (MSSs) goes hand in hand with assessing the quality of these complex systems. Therefore, reliable reference information of superior accuracy is essential for validation, serving as ground truth. When the assessment is based on 3D point cloud comparison, appropriate reference environments with suitable geometries are required. However, validation of an MSS can also be performed directly on its 3D position or even its 6D pose. This is particularly suitable for systems without sensors for environmental acquisition. When using kinematic measurement systems, the temporal relationship between the MSS and the reference trajectory must be considered, which can be challenging. Modern sensors of an MSS are often synchronized to GPS time. However, this global time information is not provided for high-accuracy tracking sensors such as robotic total stations (RTSs) or laser trackers (LTs). Instead, only a reference to an internal sensor time is implemented, which does not meet the highest quality requirements for reference trajectories. Depending on the motion speed, time offsets in the millisecond range can lead to significant trajectory inaccuracies. This paper presents investigations for GPS time synchronization of the polar measurement elements of both RTS and LT from Leica Geosystems. While the LT uses a precise trigger signal for the time link, the RTS requires the Measure & Stream application provided by the instrument manufacturer. The two different approaches are presented theoretically. Based on empirical long-term studies, their possibilities and limitations are critically discussed. For the high-frequency LT, reference trajectories with precise synchronization based on GPS time can be reliably realized. With an RTS, improved synchronization can be achieved by using Measure & Stream. Thus, 43 % lower tangential deviations from the reference could be achieved compared to the raw data. However, there are still inconstant time offsets of 63.9 ms on average. Depending on the speed of the target, this can lead to significant position deviations. Further investigations are required. In general, the developed approaches for the realization of GPS-synchronized reference trajectories can be used not only for the quality assessment of MSS, but also for monitoring or kinematic positioning applications. [ABSTRACT FROM AUTHOR]

The ultra-wideband (UWB) technology has been increasingly recognized as an efficacious strategy for Indoor Positioning Systems (IPSs). However, the accuracy of the UWB system can be severely degraded by non-line-of-sight (NLOS) errors. In this study, we proposed a new method to reduce the UWB positioning error in such an indoor environment. We developed a system consisting of a Robotic Total Station (RTS), four UWB base stations, a moving target (including a prism and a UWB tag), and a PC. The observed coordinates of the moving target, captured using millimeter precision from an RTS device, served as the ground truth for calculating the positioning errors of the UWB tag. In a significant NLOS scenario, the UWB's three-dimensional positioning error was identified to exceed the nominal value declared by the manufacturer by a factor of more than three. A detailed analysis revealed that each coordinate component's error distribution pattern demonstrated considerable variance. To reduce the NLOS error, we designed a combined multilayer neural network that simultaneously fits errors on all three coordinate components and three separate multilayer networks, each dedicated to optimizing errors on a single coordinate component. All networks were trained and verified by benchmark errors obtained from the RTS. The results showed that neural networks outperform the traditional methods, attributed to their strong nonlinear modelling ability, thereby significantly improving the external accuracy by an average reduction in RMSE by 61% and 72%. It is evident that the proposed separate networks would be more suitable for NLOS positioning problems than a combined network. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rockfall phenomena are considered highly dangerous due to their rapid evolution and difficult prediction without applying preventive monitoring and mitigation actions. This research investigates a hazardous site in the Municipality of Vecchiano (Province of Pisa, Italy), characterized by vertical rock walls prone to instability due to heavy fracturing and karst phenomena. The presence of anthropical structures and a public road at the bottom of the slopes increases the vulnerability of the site and the site’s risk. To create a comprehensive geological model of the area, Unmanned Aircraft System (UAS) photogrammetric surveys were conducted to create a 3D model useful in photointerpretation. In accessible and safe areas for personnel, engineering–geological surveys were carried out to characterize the rock mass and to define the portion of rock walls to be monitored. Results from nine multitemporal Robotic Total Station (RTS) measurement campaigns show that no monitoring prisms recorded significant displacement trends, both on the horizontal and vertical plane and in differential slope distance. Additionally, satellite Persistent Scatterer Interferometry (PSI) analysis indicates that the slopes were stable over the two years of study. The integration of these analysis techniques has proven to be an efficient solution for assessing slope stability in this specific rockfall-prone area.

Robotic Total Stations (RTS) are fully automated theodolites with electronic distance measurement (EDM) that include a number of additional tools (e.g., camera, laser rangefinder, onboard computer, and tracking software, etc.) enabling them to work autonomously. The added tools make RTSs able to track mobile targets on civil structures thus opening to the use of RTSs in structural monitoring. Unfortunately, the available RTSs are able to track a target up to a motion rate of 3 Hz. Reducing mobile masses is a viable design strategy for extending this frequency border. Such a strategy is pursued in this study by proposing the use of parallel pointing systems (PPS) as basic mechanical architectures for RTSs. The literature on PPSs is reviewed and the applicable PPS architectures are selected. Successively, the selected architectures are sized according to RTSs' functional requirements, and the positioning precision of the sized mechanisms is evaluated. The result of this study is that there are three PPS architectures suitable for RTSs, whose detailed comparison is also presented. [ABSTRACT FROM AUTHOR]

The ultra-wideband (UWB) technology has been increasingly recognized as an efficacious strategy for Indoor Positioning Systems (IPSs). However, the accuracy of the UWB system can be severely degraded by non-line-of-sight (NLOS) errors. In this study, we proposed a new method to reduce the UWB positioning error in such an indoor environment. We developed a system consisting of a Robotic Total Station (RTS), four UWB base stations, a moving target (including a prism and a UWB tag), and a PC. The observed coordinates of the moving target, captured using millimeter precision from an RTS device, served as the ground truth for calculating the positioning errors of the UWB tag. In a significant NLOS scenario, the UWB’s three-dimensional positioning error was identified to exceed the nominal value declared by the manufacturer by a factor of more than three. A detailed analysis revealed that each coordinate component’s error distribution pattern demonstrated considerable variance. To reduce the NLOS error, we designed a combined multilayer neural network that simultaneously fits errors on all three coordinate components and three separate multilayer networks, each dedicated to optimizing errors on a single coordinate component. All networks were trained and verified by benchmark errors obtained from the RTS. The results showed that neural networks outperform the traditional methods, attributed to their strong nonlinear modelling ability, thereby significantly improving the external accuracy by an average reduction in RMSE by 61% and 72%. It is evident that the proposed separate networks would be more suitable for NLOS positioning problems than a combined network.

The total station is the most basic geodetic measuring instrument, locally the most accurate and versatile. Its accuracy is the cornerstone of its use and is defined by the standard deviations of horizontal direction, zenith angle and slope distance measurements. These accuracy parameters are given by the manufacturer, but these are only valid under optimum measurement conditions. To ensure the credibility and reliability of the measurements, these values must be periodically ascertained or determined for atypical measurement configurations or measurement conditions. Standardised procedures are used for this purpose, but in our opinion, they do not reflect the full influence of the measuring conditions and other measuring aids. A comprehensive determination of the accuracies (variation components) from the alignment, where all possible influences in a given situation are applied, may be considered the most appropriate for determining the angular accuracy of measurements. Such atypical conditions are certainly represented by geodetic measurements in the confined spaces of an underground mine. Thus, an experimental determination of the accuracy of four different robotic total stations was carried out at the Center of experimental geotechnics in a mine Josef teaching centre (CTU in Prague), and the Frstner method was used to determine the variation components. A network of 6 stations and 8 target points was designed. The grid size was approximately 32x21 m with 4 - 31 m lengths. A network with the same configuration was also duplicated at the surface to assess whether the accuracy is different in underground and how the results will correspond to the accuracy claimed by the manufacturers. The result of the testing is that the accuracy claimed by the manufacturers is maintained even under such difficult measurement conditions in narrow corridors and with short sights. The overall evaluation also found that the accuracy achieved underground and on the surface is identical, although it varies from instrument to instrument. [ABSTRACT FROM AUTHOR]

Robotic Total Stations (RTS) are fully automated theodolites with electronic distance measurement (EDM) that include a number of additional tools (e.g., camera, laser rangefinder, onboard computer, and tracking software, etc.) enabling them to work autonomously. The added tools make RTSs able to track mobile targets on civil structures thus opening to the use of RTSs in structural monitoring. Unfortunately, the available RTSs are able to track a target up to a motion rate of 3 Hz. Reducing mobile masses is a viable design strategy for extending this frequency border. Such a strategy is pursued in this study by proposing the use of parallel pointing systems (PPS) as basic mechanical architectures for RTSs. The literature on PPSs is reviewed and the applicable PPS architectures are selected. Successively, the selected architectures are sized according to RTSs’ functional requirements, and the positioning precision of the sized mechanisms is evaluated. The result of this study is that there are three PPS architectures suitable for RTSs, whose detailed comparison is also presented.

Earth flows are complex gravitational events characterised by a heterogeneous displacement pattern in terms of scale, style, and orientation. As a result, their monitoring, for both knowledge and emergency purposes, represents a relevant challenge in the field of engineering geology. This paper aims to assess the capabilities, peculiarities, and limitations of different remote sensing monitoring techniques through their application to the Pietrafitta earth flow (Southern Italy). The research compared and combined data collected during the main landslide reactivations by different ground-based remote sensors such as Robotic Total Station (R-TS), Terrestrial Synthetic Aperture Radar Interferometry (T-InSAR), and Terrestrial Laser Scanner (TLS), with data being derived by satellite-based Digital Image Correlation (DIC) analysis. The comparison between R-TS and T-InSAR measurements showed that, despite their different spatial and temporal resolutions, the observed deformation trends remain approximately coherent. On the other hand, DIC analysis was able to detect a kinematic process, such as the expansion of the landslide channel, which was not detected by the other techniques used. The results suggest that, when faced with complex events, the use of a single monitoring technique may not be enough to fully observe and understand the processes taking place. Therefore, the limitations of each different technique alone can be solved by a multi-sensor monitoring approach. [ABSTRACT FROM AUTHOR]

Featured Application: As a result of inter-university cooperation, the authors have developed a technological line of 3D printing allowing to build a dedicated protective housing for precise, robotic electronic total stations operating in a displacement monitoring system on a construction site or mining areas. Construction works, especially in the case of large road or tunnel investments, require the active participation of surveyors. It applies to classic geodetic procedures such as staking out or conducting control measurements and continuously monitoring displacements and deformations. Negative factors at surveying sites may hinder the implementation or directly affect the instruments, especially total stations. Heavy dust and rainfall containing harmful and destructive substances can be mentioned here. Contemporary measuring instruments are technologically complex and expensive devices, often exposed to the sun, wind, and frost. To mainly protect robotic total stations, various preventing housings are used. Practice shows, however, that these are half-hearted solutions, often negatively influencing the accuracy of the surveys. Based on the authors' professional and scientific experience, a technological line using the modeling and 3D printing of protective housings for robotic electronic total stations has been developed. The workflow includes dedicated online modeling and printing unique instrument covers that best suit certain sites. The prototype was shielded with an additional hydrophobic layer and tested in a geodetic laboratory. The validation results confirm the high usability of the technological line while maintaining the appropriate millimeter level positioning accuracy and effectiveness of the geodetic monitoring. [ABSTRACT FROM AUTHOR]

TLS is nowadays often used for deformation monitoring. As it is not able to scan identical points in different time epochs, mathematical models of objects derived from point clouds have to be used. The most common geometric form to describe built objects is a plane, which can be described by four parameters. In this study, we aimed to find out how small changes in the parameters of the plane can be detected by TLS. We aimed to eliminate all possible factors that influence the scanning. Then, we shifted and tilted a finite physical representation of a plane in a controlled way. After each controlled change, the board was scanned several times and the parameters of the plane were calculated. We used two different types of scanning devices and compared their performance. The changes in the plane parameters were compared with the actual change values and statistically tested. The results show that TLS detects shifts in the millimetre range and tilts of 150″ (for a 1 m plane). A robotic total station can achieve twice the precision of TLS despite lower density and slower performance. For deformation monitoring, we strongly recommend repeating each scan several times (i) to check for gross errors and (ii) to obtain a realistic precision estimate. [ABSTRACT FROM AUTHOR]

Copyright of Türkiye Fotogrametri Dergisi is the property of Mersin University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Earth flows are complex gravitational events characterised by a heterogeneous displacement pattern in terms of scale, style, and orientation. As a result, their monitoring, for both knowledge and emergency purposes, represents a relevant challenge in the field of engineering geology. This paper aims to assess the capabilities, peculiarities, and limitations of different remote sensing monitoring techniques through their application to the Pietrafitta earth flow (Southern Italy). The research compared and combined data collected during the main landslide reactivations by different ground-based remote sensors such as Robotic Total Station (R-TS), Terrestrial Synthetic Aperture Radar Interferometry (T-InSAR), and Terrestrial Laser Scanner (TLS), with data being derived by satellite-based Digital Image Correlation (DIC) analysis. The comparison between R-TS and T-InSAR measurements showed that, despite their different spatial and temporal resolutions, the observed deformation trends remain approximately coherent. On the other hand, DIC analysis was able to detect a kinematic process, such as the expansion of the landslide channel, which was not detected by the other techniques used. The results suggest that, when faced with complex events, the use of a single monitoring technique may not be enough to fully observe and understand the processes taking place. Therefore, the limitations of each different technique alone can be solved by a multi-sensor monitoring approach.

Building structures are subject to various deformations caused by external and internal factors. Deformations are determined by various methods in the form of monitoring. It is very important to monitor the dynamic vibration response on bridge structures since these measurements allow us to identify any possible damage over time and take appropriate action. Our experiment, described in this article, is based on the use of non-contact methods, among which we used a geodetic instrument RTS (Robotic Total Station) and a seismograph to measure vibrations. The purpose and novelty of our work are reflected in the use of geodetic instruments to determine the dynamic response and synchronization of the obtained results. When using RTS technology, we increased data acquisition from 9 to 26 measurements per second. Comparative analysis of the measured signals was performed using FFT (Fast Fourier Transformation) and LSP (Lomb–Scargle Periodogram), based on LSSA (Least-Squares Spectral Analysis). The results showed us that when using the RTS geodetic instrument, it is possible to achieve frequency spectra comparable to those measured with a seismograph instrument. By increasing the number of measurements, the RTS method can be used to obtain more continuous data, which are essential for dynamic analyses. [ABSTRACT FROM AUTHOR]

Determining the displacements and consequent deformations of structures is a demanding branch of engineering. Displacements are most often determined by geodetic methods, among which high-precision non-contact methods have recently taken the lead. Engineering geodesy is an indispensable part of construction projects. In the desire for efficient and fast measurements, the technology of terrestrial laser scanning (TLS) and the use of robotic total station (RTS) and other geodetic methods are becoming more and more useful for engineers. In the presented study, we focused on the measurement and comparison of vertical displacements with various mentioned equipment and the determination of the influence of meteorological conditions on the displacements of timber beams that we used to perform the experiment. Measurements were performed both in the laboratory and outdoors. A novelty in the work was the use of a TLS scanner to determine the evaluation of small value displacements and the analysis of the usability of geodetic measuring equipment. In the Materials and Methods section, we describe the equipment used and the characteristics of the beams. The Results section describes the experimental outcomes, which include the performance of experimental analysis of vertical displacements of timber beams under different meteorological conditions. Altogether, the results consist of geodetic measurements and the processing of measured data. The results of measurements of vertical displacements with a terrestrial laser scanner were compared with the results obtained with a robotic total station were evaluated and compared with the displacements calculated from static analysis and the results of other methods used. [ABSTRACT FROM AUTHOR]

Building construction is the subject of various factors and their consequences must be regularly monitored; this can be carried out in the form of control measurements or monitoring. This article aims to show the usability of geodetic non-contact methods in defining the dynamic response of structures. The lamella on which various methods for monitoring the dynamic response was used for simulation; the emphasis is on a modern geodetic method using a Robotic Total Station (RTS). To determine the dynamic response, the algorithm for the determination of the harmonic oscillation´s average amplitude and the methods of the spectral analysis of the sampled data is further described. The results obtained with the RTS method have shown a high level of reliability for the determination of dynamic response.

Construction works, especially in the case of large road or tunnel investments, require the active participation of surveyors. It applies to classic geodetic procedures such as staking out or conducting control measurements and continuously monitoring displacements and deformations. Negative factors at surveying sites may hinder the implementation or directly affect the instruments, especially total stations. Heavy dust and rainfall containing harmful and destructive substances can be mentioned here. Contemporary measuring instruments are technologically complex and expensive devices, often exposed to the sun, wind, and frost. To mainly protect robotic total stations, various preventing housings are used. Practice shows, however, that these are half-hearted solutions, often negatively influencing the accuracy of the surveys. Based on the authors’ professional and scientific experience, a technological line using the modeling and 3D printing of protective housings for robotic electronic total stations has been developed. The workflow includes dedicated online modeling and printing unique instrument covers that best suit certain sites. The prototype was shielded with an additional hydrophobic layer and tested in a geodetic laboratory. The validation results confirm the high usability of the technological line while maintaining the appropriate millimeter level positioning accuracy and effectiveness of the geodetic monitoring.

TLS is nowadays often used for deformation monitoring. As it is not able to scan identical points in different time epochs, mathematical models of objects derived from point clouds have to be used. The most common geometric form to describe built objects is a plane, which can be described by four parameters. In this study, we aimed to find out how small changes in the parameters of the plane can be detected by TLS. We aimed to eliminate all possible factors that influence the scanning. Then, we shifted and tilted a finite physical representation of a plane in a controlled way. After each controlled change, the board was scanned several times and the parameters of the plane were calculated. We used two different types of scanning devices and compared their performance. The changes in the plane parameters were compared with the actual change values and statistically tested. The results show that TLS detects shifts in the millimetre range and tilts of 150″ (for a 1 m plane). A robotic total station can achieve twice the precision of TLS despite lower density and slower performance. For deformation monitoring, we strongly recommend repeating each scan several times (i) to check for gross errors and (ii) to obtain a realistic precision estimate.

Despite the increasing interest in kinematic data acquisition, Robotic Total Stations (RTSs) are still relatively seldom used. No matter if Mobile Mapping Systems or Control & Guidance, GNSS is mostly used as position sensor, which limits the application to outdoor areas. For indoor applications, a combination of relative sensors is usually employed. One reason why RTSs are not used is the challenging time referencing and synchronization. In this work we analyze the challenges of a synchronized kinematic application of RTSs and present solutions. Our approach is based on a wireless network synchronization to establish a precise temporal reference frame. The achievable synchronization quality is thoroughly examined. In addition we develop a kinematic model of spherical measurements, that incorporates timing related parameters. To estimate these parameters we propose a temporal calibration utilizing an industrial robot. Both parts of our approach are evaluated using a test setup of two total stations, proofing an overall synchronization accuracy of 0.2 ms. An overall horizontal kinematic point accuracy of 2.3 mm reveals the potential of sufficiently synchronized RTSs. [ABSTRACT FROM AUTHOR]

In order to solve automatic guidance problem of long-distance curved pipe jacking, an automatic guidance system for pipe jacking based on single-prism is presented in this paper. The single-prism system can automatically acquire 3D coordinates of the center of tunnel-boring-machine (TBM) tail, and can acquire horizontal and level deviations of the center of TBM tail with respect to the designed tunnel axis. The single-prism system has been successfully applied in practical pipe jacking projects. In order to obtain 3D orientations of TBM, an automatic guidance system for pipe jacking based on multivariate-data fusion is further proposed on the basis of the single-prism system. Mathematical models of the multivariate-data system have been tested in the ground testing site, and results showed that those models are feasible. [ABSTRACT FROM AUTHOR]

To validate the accuracy and reliability of onboard sensors for object detection and localization for driver assistance, as well as autonomous driving applications under realistic conditions (indoors and outdoors), a novel tracking system is presented. This tracking system is developed to determine the position and orientation of a slow-moving vehicle during test maneuvers within a reference environment (e.g., car during parking maneuvers), independent of the onboard sensors. One requirement is a 6 degree of freedom (DoF) pose with position uncertainty below 5 mm (3σ), orientation uncertainty below 0.3° (3σ), at a frequency higher than 20 Hz, and with a latency smaller than 500 ms. To compare the results from the reference system with the vehicle’s onboard system, synchronization via a Precision Time Protocol (PTP) and system interoperability to a robot operating system (ROS) are achieved. The developed system combines motion capture cameras mounted in a 360° panorama view setup on the vehicle, measuring retroreflective markers distributed over the test site with known coordinates, while robotic total stations measure a prism on the vehicle. A point cloud of the test site serves as a digital twin of the environment, in which the movement of the vehicle is visualized. The results have shown that the fused measurements of these sensors complement each other, so that the accuracy requirements for the 6 DoF pose can be met while allowing a flexible installation in different environments.

Building structures are subject to various deformations caused by external and internal factors. Deformations are determined by various methods in the form of monitoring. It is very important to monitor the dynamic vibration response on bridge structures since these measurements allow us to identify any possible damage over time and take appropriate action. Our experiment, described in this article, is based on the use of non-contact methods, among which we used a geodetic instrument RTS (Robotic Total Station) and a seismograph to measure vibrations. The purpose and novelty of our work are reflected in the use of geodetic instruments to determine the dynamic response and synchronization of the obtained results. When using RTS technology, we increased data acquisition from 9 to 26 measurements per second. Comparative analysis of the measured signals was performed using FFT (Fast Fourier Transformation) and LSP (Lomb–Scargle Periodogram), based on LSSA (Least-Squares Spectral Analysis). The results showed us that when using the RTS geodetic instrument, it is possible to achieve frequency spectra comparable to those measured with a seismograph instrument. By increasing the number of measurements, the RTS method can be used to obtain more continuous data, which are essential for dynamic analyses.

Determining the displacements and consequent deformations of structures is a demanding branch of engineering. Displacements are most often determined by geodetic methods, among which high-precision non-contact methods have recently taken the lead. Engineering geodesy is an indispensable part of construction projects. In the desire for efficient and fast measurements, the technology of terrestrial laser scanning (TLS) and the use of robotic total station (RTS) and other geodetic methods are becoming more and more useful for engineers. In the presented study, we focused on the measurement and comparison of vertical displacements with various mentioned equipment and the determination of the influence of meteorological conditions on the displacements of timber beams that we used to perform the experiment. Measurements were performed both in the laboratory and outdoors. A novelty in the work was the use of a TLS scanner to determine the evaluation of small value displacements and the analysis of the usability of geodetic measuring equipment. In the Materials and Methods section, we describe the equipment used and the characteristics of the beams. The Results section describes the experimental outcomes, which include the performance of experimental analysis of vertical displacements of timber beams under different meteorological conditions. Altogether, the results consist of geodetic measurements and the processing of measured data. The results of measurements of vertical displacements with a terrestrial laser scanner were compared with the results obtained with a robotic total station were evaluated and compared with the displacements calculated from static analysis and the results of other methods used.

Geodetic measuring methods are widely used in the course of various geotechnical works. The main purpose is usually related to the location in space, geometrical dimensions, settlements, deflections, and other forms of displacements and their consequences. This study focuses on the application of selected surveying methods in static load tests (SLTs) of foundation piles. Basic aspects of the SLT are presented in the introductory section, together with the explanation of the authors’ motivation behind the novel (but already sufficiently tested) application of remote methods introduced to confirm, through inverse analysis, the load applied to the pile head under testing at every stage of its loading. Materials and methods are described in the second section in order to provide basic information on the test site and principles of the SLT method applied. The case study shows the methodology of displacement control in the particular test, which is described in light of a presented review of geodetic techniques for displacement control, especially terrestrial laser scanning and robotic tacheometry. The geotechnical testing procedure, which is of secondary importance for the current study, is also introduced in order to emphasize the versatility of the proposed method. Special attention is paid to inverse analysis (controlling of the pile loading force on the basis of measured deflections, and static calculations by means of standard structural analysis and the finite element method (FEM)) as a tool to raise the credibility of the obtained SLT results. The present case study from just one SLT, instrumented with various geodetic instrumentation, shows the results of a real-world dimensions test. The obtained variability of the loading force within a range of 15% (depending on real beam stiffness) proves good prospects for the application of the proposed idea in practice. The results are discussed mainly in light of the previous authors’ experience with the application of remote techniques for reliable displacement control. As only a few references could be found (mainly by private communication), both the prospects for new developments using faster and more accurate instruments as well as the need for the validation of these findings on a larger number of SLTs (with a very precise definition of beam stiffness) are underlined in the final remarks.

Development and verification of real-time algorithms for robotic total stations usually require hard-ware-in-the-loop approaches, which can be complex and time-consuming. Simulator-in-the-loop can be used instead, but the design of a simulation environment and sufficient detailed modeling of the hardware are required. Typically, device specification and calibration data are provided by the device manufacturers and are used by the device drivers. However, geometric models of robotic total stations cannot be used directly with existing ro-botic simulators. Model details are often treated as company secrets, and no source code of device drivers is available to the public. In this paper, we present a complete workflow for automatic geometric model extraction of robotic total stations using the Denavit-Hartenberg convention. We provide a complete set of Denavit-Hartenberg parameters for an exemplary ro-botic total station. These parameters can be used in existing robotic simulators without modifications. Furthermore, we analyze the difference between the extracted geometric model, the calibrated model, which is used by the device drivers, and the standard spherical representation for 3D point measurements of the device. [ABSTRACT FROM AUTHOR]

This article proposes a contribution to the inspection procedures of curved reinforced concrete road bridges through a short-term monitoring plan using topographic techniques during an ambient vibration test (AVT) under normal traffic conditions. The proposed monitoring method was used to determine the 3D displacements in the observed points, which enabled the evaluation of vibrations of two points on the bridge deck in the vertical (Z), horizontal (Y)—perpendicular to track direction—and longitudinal (X) directions of the track. The application consisted of measurements performed under normal traffic conditions with two RTSs with a nominal sampling rate of 10 Hz. The targets were two prisms located on opposite edges of the runway and perpendicular to the traffic direction. A tri-dimensional view of the residuals from the measured coordinates and Morlet continuous wavelet transform (CWT) are used to establish the time and frequency-domain of the bridge vibrations and analyze the behavior and movement of the midspan in an AVT. This study confirms the feasibility of using high sampling rate RTSs for monitoring dynamic responses of small concrete bridges without interrupting traffic on highways. [ABSTRACT FROM AUTHOR]

Building construction is the subject of various factors and their consequences must be regularly monitored; this can be carried out in the form of control measurements or monitoring. This article aims to show the usability of geodetic non-contact methods in defining the dynamic response of structures. The lamella on which various methods for monitoring the dynamic response was used for simulation; the emphasis is on a modern geodetic method using a Robotic Total Station (RTS). To determine the dynamic response, the algorithm for the determination of the harmonic oscillation's average amplitude and the methods of the spectral analysis of the sampled data is further described. The results obtained with the RTS method have shown a high level of reliability for the determination of dynamic response. [ABSTRACT FROM AUTHOR]

In this paper, we present an alternate method for the generation and implementation of the sensor measurement variance used in an Extended Kalman Filter (EKF). Furthermore, it demonstrates the limitations of a conventional EKF implementation and postulates an alternate form for representing the sensor measurement variance by extending and improving the characterisation methodology presented in the previous work. As presented in earlier work, the use of surveying grade optical measurement instruments allows for a more effective characterisation of Ultra-Wide Band (UWB) localisation sensors; however, in cluttered environments, the sensor measurement variance will change, making this method not robust. To compensate for the noisier readings, an EKF using a model based sensor measurement variance was developed. This approach allows for a more accurate representation of the sensor measurement variance and leads to a more robust state estimation system. Simulations were run using synthetic data in order to test the effectiveness of the EKF against the originally developed EKF; next, the new EKF was compared to the original EKF using real world data. The new EKF was shown to function much more stably and consistently in less ideal environments for UWB deployment than the previous version.

Our proposal for this paper is to identify and introduce topographic methods and technologies to ensure the best monitoring of buildings of vital importance for society or those with significant structural damage due to compaction of soil. The main purpose of this study is to find and compare contemporary methods that have been developed in recent years and are used in applied topography, replacing traditional methods successfully. Recently, digital technology has evolved at the same time with society needs and development. The use of 3D laser scanner, combined GPS stations, laser or photogrammetric scanning, total or modern robotic stations and drones, appear to be the most suitable solutions nowadays. A comparative research using different scientific papers will be presented in a short table. Each method is described with its advantages and disadvantages. [ABSTRACT FROM AUTHOR]

High sampling-rate robotic total stations (RTS) are emerging tools for monitoring both semi-static and dynamic displacement responses of bridge structures, due to rapid advancements in data sampling rates and tracking speeds. However, the dynamic measurement accuracy of the RTS needs to be fully assessed, especially for different sighting distances. To this end, groups of static and dynamic evaluating tests were carried out on university campuses, and a further in-situ performance assessment with RTS was performed for monitoring dynamic responses of a long suspension bridge in Changsha, China, with a central span of 328 m. A standardized procedure was developed to process these RTS measurements. The background noise in RTS measurements for sighting-distances varying from 25 m to 400 m only results in minor errors which mainly distribute in a frequency range of less than 0.1 Hz. The vibration displacements of an oscillating platform between the RTS and an accelerometer are compared in both horizontal and vertical directions to demonstrate the sufficient accuracy of the RTS measurements. The in-situ experiment also leads to a similar conclusion. This study confirms that the feasibility of using high sampling-rate RTS for monitoring dynamic responses of bridges. [ABSTRACT FROM AUTHOR]

Monitoring applications may require operating robotic total stations (RTS) at the limit of their sensitivity with respect to target displacements. Thorough understanding and mitigation of systematic effects are required in order to reach or push this limit. We investigate some of these effects, in particular effects external to the total station, using data and experience gained from a continuously operating monitoring system installed at the terminus of the Great Aletsch Glacier in Switzerland. The system consists of two robotic total stations, about 60 prisms, four global navigation satellite system (GNSS) receivers, thermocouples, inclinometers, and meteo-sensors. The purpose of the monitoring is to study reversible deformations of the adjacent slopes, likely driven by snowmelt and mountain water level changes. The deformations reach the millimeter- to centimeter-level and shall be studied on time scales ranging from annual to sub-annual, and ideally even down to daily or sub-daily resolution. Our investigation focuses on four aspects: protective housing, pillar stability, refraction, and stability of orientation, all of which were found to affect the measurements on the milligon-level with lines-of-sight of up to 2 km. The results highlight signatures of apparent point displacements, and the discussion comprises approaches to bounding or mitigating these effects which may also be expected in similar monitoring situations at other locations. [ABSTRACT FROM AUTHOR]

Robotic total stations (RTS) are frequently used for the measurement of temperature induced bridge deformations or during load testing of bridges. In experimental setups, total stations have also been used for the measurement of dynamic bridge deformations. However, with standard configurations the measurement rate is not constant and on average an update rate of 7-10Hz can be achieved. This is not sufficient for the vibration monitoring of bridges considering their natural frequencies which are also in the same range. In this paper, we present different approaches to overcome these problems. In the first two approaches we demonstrate how the measurement rate to prisms can be increased to 20Hz to determine vertical deformations of bridges. Critical aspects like the measurement resolution of the automated target tracking and the correct sequence of steering commands are discussed. In another approach we demonstrate how vertical bridge vibrations can be measured using an image assisted total station (IATS) and corresponding processing techniques. The advantage of image-based methods is that structural features of a bridge like bolts can be used as targets. Therefore, no expensive prisms have to be mounted and access to the bridge is not required. All approaches are verified by laboratory investigations and their suitability is proven in a field experiment on a 74m long footbridge. In this field experiment the natural frequencies derived from the total station measurements are compared to the results of accelerometer measurements. [ABSTRACT FROM AUTHOR]

Recent developments in localisation systems for autonomous robotic technology have been a driving factor in the deployment of robots in a wide variety of environments. Estimating sensor measurement noise is an essential factor when producing uncertainty models for state-of-the-art robotic positioning systems. In this paper, a surveying grade optical instrument in the form of a Trimble S7 Robotic Total Station is utilised to dynamically characterise the error of positioning sensors of a ground based unmanned robot. The error characteristics are used as inputs into the construction of a Localisation Extended Kalman Filter which fuses Pozyx Ultra-wideband range measurements with odometry to obtain an optimal position estimation, all whilst using the path generated from the remote tracking feature of the Robotic Total Station as a ground truth metric. Experiments show that the proposed method yields an improved positional estimation compared to the Pozyx systems’ native firmware algorithm as well as producing a smoother trajectory.

Modern robotic total stations (RTS) have the ability to automatically aim, search and track moving targets at high precision thereby enabling kinematic positioning. However, the internal subsystems of the RTS (distance and direction) exhibit time delays which limit the precision positioning of a moving target. These effects are investigated with tracking experiments on a known circular and linear path. A second part of this research investigates small-scale unmanned aerial vehicles (UAV) which use navigation quality GPS as a priori coordinates for photogrammetric processing of acquired images. RTS kinematic positioning was applied to a UAV in a field trial to improve a priori image coordinates and evaluate the method for direct geo-referencing. [ABSTRACT FROM AUTHOR]

Urban tunnel projects such as new metro lines face particular challenges. Shallow overburden, difficult (hydro)geological conditions and sensitive buildings in close proximity are risks that often cannot be avoided, demanding large and complex geotechnical monitoring programmes. This paper considers the current situation of tunnel monitoring in urban environments and describes two specific monitoring solutions, one for shafts and one for structures, and emphasises the importance of efficient data management with the assistance of a tunnel information system. Finally, the paper gives an overview of recent research activity and emerging sensing technologies. [ABSTRACT FROM AUTHOR]