A novel wireless low-cost inclinometer made from combining the measurements of multiple MEMS gyroscopes and accelerometers

Structural damage detection using inclinometers is getting wide attention from researchers. However, the high price of inclinometers limits this system to unique structures with a relatively high structural health monitoring (SHM) budget. This paper presents a novel low-cost inclinometer, the low-cost adaptable reliable angle-meter (LARA), which combines five gyroscopes and five accelerometers to measure inclination. LARA incorporates Internet of Things (IoT)-based microcontroller technology enabling wireless data streaming and free commercial software for data acquisition. This paper investigates the accuracy, resolution, Allan variance and standard deviation of LARA produced with a different number of combined circuits, including an accelerometer and a gyroscope. To validate the accuracy and resolution of the developed device, its results are compared with those obtained by numerical slope calculations and a commercial inclinometer (HI-INC) in laboratory conditions. The results of a load test experiment on a simple beam model show the high accuracy of LARA (0.003 degrees). The affordability and high accuracy of LARA make it applicable for structural damage detection on bridges using inclinometers.The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding provided through the research project BIA2017-86811-C2-1-R directed by José Turmo and BIA2017-86811-C2-2-R. All these projects are funded with FEDER funds. The authors are also indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya, Catalunya, Spain for the funding provided through Agaur (2017 SGR 1482). It is also to be noted that funding for this research has been provided for Seyedmilad Komarizadehasl by Spanish Agencia Estatal de Investigación del Ministerio de Ciencia Innovación y Universidades grant and the Fondo Social Europeo grant (PRE2018-083238).Peer ReviewedPostprint (published version

Innovative Methods and Materials in Structural Health Monitoring of Civil Infrastructures

In the past, when elements in sructures were composed of perishable materials, such as wood, the maintenance of houses, bridges, etc., was considered of vital importance for their safe use and to preserve their efficiency. With the advent of materials such as reinforced concrete and steel, given their relatively long useful life, periodic and constant maintenance has often been considered a secondary concern. When it was realized that even for structures fabricated with these materials that the useful life has an end and that it was being approached, planning maintenance became an important and non-negligible aspect. Thus, the concept of structural health monitoring (SHM) was introduced, designed, and implemented as a multidisciplinary method. Computational mechanics, static and dynamic analysis of structures, electronics, sensors, and, recently, the Internet of Things (IoT) and artificial intelligence (AI) are required, but it is also important to consider new materials, especially those with intrinsic self-diagnosis characteristics, and to use measurement and survey methods typical of modern geomatics, such as satellite surveys and highly sophisticated laser tools

Using Low-cost IoT-based inclinometers for damage detection of a Bridge model

Nowadays, researchers are paying close attention to using inclinometers for Structural Health Monitoring (SHM) applications. Moreover, the applications based on using inclinometers can detect the magnitude and location of bridge pathologies. However, as these applications are based on expensive commercial inclinometers, their use is typically exclusive to the SHM of structures with a high monitoring budget. There is a gap in the literature with the development and validation of low-cost accurate angular-meters for decreasing the monitoring cost of inclinometer-based damage detection applications. This work aims to develop low-cost IoT-based inclinometers for detecting damage in bridge structures. The Low-cost Adaptable Reliable Angle-meter (LARA) is a novel inclinometer that accurately measures an induced inclination by combining the measurements of five gyroscopes and five accelerometers. The accuracy, resolution, Allan variance, and standard deviation of LARA are examined through laboratory experiments and are compared with those obtained by numerical slope calculations and a commercial inclinometer (HI-INC). For further experimental validation, a robotic vehicle model is designed and developed to simulate a moving load over a bridge model. The vehicle model integrates IoT technology and can be utilized in different damage detection experiments. The outcomes of a load test experiment using a simple beam model demonstrate the high accuracy (0.003 degrees) of LARA measurements. LARA may be used for structural damage identification and location in bridges utilizing inclinometers because of its low cost and high accuracy

Utilization of IGS Information for Improved Real-time GPS Positioning

The estimation of a precise user\u27s position is a difficult and complex problem. In addition, the use of geodetic grade position instruments is often not possible for Small Unmanned Aerial Vehicle (SUAV) systems. However, the availability of the global navigation satellite system (GNSS) and International GNSS Service (IGS) predicted product data allows an attempt to increase the precision of a navigation algorithm, which is the aim in this thesis.;The utilization of this information within an algorithm work environment is a complex problem, requiring the development of multiple tools in order to use and access the IGS raw and product data. Therefore, the overall goal of this research project was the development of these tools using MATLAB RTM. The IGS information provided by these tools allows access to a particular set of product and raw data files. The available predicted product data is used to increase the precision of the position estimate for a real-time application. Within this, the conversion from a long time interval to a fast update rate was determined. The use of this information requires these tools to also include important orbit determinations of the GPS satellites.;The use of only precise satellite position information from the developed MATLAB tools is evaluated by a comparison of a position estimation algorithm using recorded satellite position information and the developed satellite position information from the IGS predicted data. The results show an increase in performance of position estimation with the use of the created MATLAB tools. A discussion in how the use of the created tools could further be expanded to increase the accuracy and precision of a position estimation algorithm is presented

Development of a Novel Handheld Device for Active Compensation of Physiological Tremor

In microsurgery, the human hand imposes certain limitations in accurately positioning the tip of a device such as scalpel. Any errors in the motion of the hand make microsurgical procedures difficult and involuntary motions such as hand tremors can make some procedures significantly difficult to perform. This is particularly true in the case of vitreoretinal microsurgery. The most familiar source of involuntary motion is physiological tremor. Real-time compensation of tremor is, therefore, necessary to assist surgeons to precisely position and manipulate the tool-tip to accurately perform a microsurgery. In this thesis, a novel handheld device (AID) is described for compensation of physiological tremor in the hand. MEMS-based accelerometers and gyroscopes have been used for sensing the motion of the hand in six degrees of freedom (DOF). An augmented state complementary Kalman filter is used to calculate 2 DOF orientation. An adaptive filtering algorithm, band-limited Multiple Fourier linear combiner (BMFLC), is used to calculate the tremor component in the hand in real-time. Ionic Polymer Metallic Composites (IPMCs) have been used as actuators for deflecting the tool-tip to compensate for the tremor

Load Estimation, Structural Identification and Human Comfort Assessment of Flexible Structures

Stadiums, pedestrian bridges, dance floors, and concert halls are distinct from other civil engineering structures due to several challenges in their design and dynamic behavior. These challenges originate from the flexible inherent nature of these structures coupled with human interactions in the form of loading. The investigations in past literature on this topic clearly state that the design of flexible structures can be improved with better load modeling strategies acquired with reliable load quantification, a deeper understanding of structural response, generation of simple and efficient human-structure interaction models and new measurement and assessment criteria for acceptable vibration levels. In contribution to these possible improvements, this dissertation taps into three specific areas: the load quantification of lively individuals or crowds, the structural identification under non-stationary and narrowband disturbances and the measurement of excessive vibration levels for human comfort. For load quantification, a computer vision based approach capable of tracking both individual and crowd motion is used. For structural identification, a noise-assisted Multivariate Empirical Mode Decomposition (MEMD) algorithm is incorporated into the operational modal analysis. The measurement of excessive vibration levels and the assessment of human comfort are accomplished through computer vision based human and object tracking, which provides a more convenient means for measurement and computation. All the proposed methods are tested in the laboratory environment utilizing a grandstand simulator and in the field on a pedestrian bridge and on a football stadium. Findings and interpretations from the experimental results are presented. The dissertation is concluded by highlighting the critical findings and the possible future work that may be conducted

Multistation Methods for Geotechnical Characterization using Surface Waves

This dissertation deals with soil characterization methods based on surface wave propagation applied to geotechnical engineering purposes. This topic has gained much interest in the last decade because of the appealing possibilities given by non-invasive methods, which are at once very flexible and cost effective. An overview of the properties of Rayleigh waves in layered linear elastic and linear viscoelastic media is presented, together with their applications for site characterization, of whose the SASW (Spectral Analysis of Surface Waves) method is by far the most well-known in geotechnical engineering. The research has been mainly focused on the application of multistation methods, compared with the classical two-station approach typical of the SASW method. Results from both numerical simulations and experimental testing are reported to compare two-station and multistation methods and to clarify the advantages that can be obtained using the latter ones. In particular the research has been developed following two different directions: on the one hand the application of classical geophysical analysis tools (such as domain analysis and slant stack transform) to tests performed with impulsive sources. On the other one the possibility of obtaining from surface wave testing not only a stiffness profile, but also a damping ratio profile for the site. In this respect a new method for simultaneous measurements of Rayleigh dispersion and attenuation curves is proposed. Regarding the first topic, the necessity of a multistation approach to determine the experimental dispersion test is essentially related to the spatial variation of phase velocity. Analyses in the frequency-wavenumber domain and in the frequency-slowness domain are very powerful approaches, still there was a need of studying the effects of the change of scale from geophysical applications to geotechnical ones. Indeed because of the peculiar properties of Rayleigh waves, surface testing is strongly affected by the distance travelled by the analysed wave. The numerical simulations performed in the research show that the phase velocity obtained using multistation methods with a limited number of receivers close to the source is not a modal value as it is for geophysical applications, but an apparent phase velocity arising from modal superposition. The experimental tests showed the good performances of multistation methods when compared to the SASW method. In particular some drawbacks of the latter method, due essentially to its two-station nature, are avoided and the field-testing appears to be very promising for future applications. In particular the application of the frequency-wavenumber domain analysis can lead to much faster and more stable estimates of the experimental dispersion curve and the process is easily automated, with a great saving of time and less requirement for subjective decisions. Another important advantage is given by the stability with respect to a near field effects that lead to a better reconstruction of the dispersion curve for the low frequencies and hence to a deeper characterization. The necessity of a new method for the simultaneous determination of surface wave dispersion and attenuation curves is linked to the strong coupling existing between the two. Such coupling is extremely important for the subsequent inversion process, in a consistent method leading from the field measurements to the stiffness and damping profiles. The proposed method uses a new testing configuration, designed to measure the experimental transfer function. Successively a regression process of the complex quantity with the corresponding expression obtained modelling soil as a linear viscoelastic layered system leads to the experimental dispersion and attenuation curves. Some preliminary results are reported showing very encouraging results, also if a more extensively testing programme is required for the complete validation of the metho

Development of low-cost sensors for structural health monitoring applications

(English) There is increasing interest in developing low-cost sensors for economical structural health monitoring of civil engineering infrastructures. In addition to their price, they have the additional benefit of being easily connected to low-cost microcontrollers such as Arduino. A reliable data acquisition system based on Arduino technology can further lower the cost of data collection and monitoring, enabling long-term monitoring at an affordable cost. This thesis proposes the following four high-precision low-cost monitoring systems.Firstly, to correctly measure structural responses, a Cost Hyper-Efficient Arduino Product (CHEAP) has been developed. CHEAP is a system made up of five synchronized accelerometers connected to an Arduino microcontroller that works as a data collecting device. CHEAP is a uniaxial MEMS accelerometer with a sampling frequency of 85 Hz. To validate its performance, laboratory experiments were carried out and the results were compared with those of two high-precision accelerometers (PCB393A03 and PCB 356B18).Secondly, a unique low-cost inclinometer is presented, the Low-cost Adaptable Reliable Angle-meter (LARA), which measures inclination through the fusion of different sensors: five gyroscopes and five accelerometers. LARA combines a microcontroller based on Internet of Things technology (NODEMCU), allows wireless data transmission, and free commercial software for data collection (SerialPlot). To confirm the precision and resolution of this device, its measurements under laboratory conditions were compared with the theoretical ones and with those of a commercial inclinometer (HI-INC). Laboratory results of a load test on a beam demonstrate LARA's remarkable accuracy. It is concluded that the accuracy of LARA is sufficient for its application in detecting bridge damage.Thirdly, the effect of combining similar range sensors to investigate the increase of the accuracy and mitigation of the ambiental noises, is also elucidated. To investigate the sensor combination theory, a measuring equipment composed of 75 contactless ranging sensors controlled by only two microcontrollers (Arduinos), was built. The 75 sensors are 25 HC-SR04 (analog), 25 VL53L0X (digital), and 25 VL53L1X. (digital). In addition, the impact of various environmental conditions on the standard deviation, distribution functions, and error level of these sensors (HC-SR04, VL53L0X, and VL53L1X) is determined.Finally, a novel remote versatile data acquisition system is presented that allows the recording of time with microsecond resolution for the subsequent synchronization of the acquired data of the wireless sensors located at various points of a structure. This functionality is what would allow its application to static or quasi-static load tests or to the modal analysis of structures. The system developed has a noise density of 51 g/Hz and a sampling frequency of 333 Hz. This device was used to identify the eigenfrequencies and modal analysis of several structures (polvorín footbridges in Barcelona and Andoain Bridge, Donostia-San Sebastian). The comparison of the modal analysis of the Andoain Bridge using the acquired data of the developed accelerometer and data acquisition equipment with those of commercial accelerometers (PCB 607A61) were satisfactory.The low-cost accelerometer, inclinometer and data acquisition system developed and validated in this thesis can make SHM and infrastructure damage detection a reality at low cost, long term and remotely.(Español) Cada vez hay más interés en desarrollar sensores baratos para conocer de manera económica el estado de las infraestructuras civiles. Además de su precio, estos sensores tienen la ventaja añadida de poder conectarse fácilmente a microcontroladores de bajo coste como Arduino. Un sistema fiable de adquisición de datos basado en la tecnología Arduino puede disminuir aún más el coste de la recogida de datos y la monitorización, lo que permitiría una monitorización a largo plazo a un coste asequible. Esta tesis propone los cuatro siguientes sistemas de monitorización de alta precisión y bajo coste.En primer lugar, para medir correctamente las respuestas estructurales, se ha desarrollado el Cost Hyper-Efficient Arduino Product (CHEAP). CHEAP es un sistema compuesto por cinco acelerómetros sincronizados de bajo coste conectados a un microcontrolador Arduino que hace el papel de dispositivo de recogida de datos. CHEAP es un acelerómetro MEMS uniaxial con una frecuencia de muestreo de 85 Hz. Para validar su rendimiento, se efectuaron unos experimentos de laboratorio y sus resultados se compararon con los de dos acelerómetros de alta precisión (PCB393A03 y PCB 356B18). En segundo lugar, se presenta un inclinómetro de bajo coste, un Low-cost Adaptable Reliable Angle-meter (LARA), que mide la inclinación mediante la fusión de distintos sensores: cinco giroscopios y cinco acelerómetros. LARA combina un microcontrolador basado en la tecnología del Internet de las Cosas (NODEMCU), que permite la transmisión inalámbrica de datos, y un software comercial gratuito para la recogida de datos (SerialPlot). Para confirmar la precisión y resolución de este dispositivo, se compararon sus mediciones en condiciones de laboratorio con las teóricas y con las de un inclinómetro comercial (HI-INC). Los resultados de laboratorio de una prueba de carga en una viga demuestran la notable precisión de LARA. Se concluye que la precisión de LARA es suficiente para su aplicación en la detección de daños en puentes.En tercer lugar, también se dilucida el efecto de la combinación de sensores de rango similar para investigar el aumento de la precisión y la mitigación de los ruidos ambientales. Para investigar la teoría de la combinación de sensores, se construyó un equipo de medición compuesto por 75 sensores para la medición de distancias acoplados a dos microcontroladores de Arduino. Los 75 sensores son 25 HC-SR04 (analógicos), 25 VL53L0X (digitales) y 25 VL53L1X (digitales). Además, se determina el impacto de diversas condiciones ambientales en la desviación estándar, las funciones de distribución y el nivel de error de estos sensores.Por último, se presenta un novedoso y versátil sistema de adquisición de datos a distancia que permite el registro del tiempo con una resolución de microsegundos para la sincronización posterior de las lecturas de los sensores inalámbricos situados en diversos puntos de una estructura. Esta funcionalidad es lo que permitiría su aplicación a pruebas de carga estáticas o quasi-estaticas o al análisis modal de las estructuras. El sistema desarrollado tiene una densidad de ruido de 51 g/Hz y una frecuencia de muestreo de 333 Hz. Este dispositivo se utilizó para identificar las frecuencias propias y los modos de vibración de varias estructuras (pasarelas polvorín en Barcelona y Puente de Andoain, Donostia-San Sebastian). Los modos calculados en una de ellas, el Puente de Andoain, a partir de los datos obtenidos con el acelerómetro y sistema de adquisición de datos desarrollado se comparan satisfactoriamente con los de sensores comerciales (PCB 607A61). El acelerómetro, el inclinómetro y el sistema de adquisición de datos de bajo coste desarrollados y validados en esta tesis pueden hacer realidad la SHM y la detección de daños en infraestructuras a bajo coste, a largo plazo y de forma remota.Postprint (published version

A survey of sag monitoring methods for power grid transmission lines

The transmission line is a fundamental asset in the power grid. The sag condition of the transmission line between two support towers requires accurate real-time monitoring in order to avoid any health and safety hazards or power failure. In this paper, state-of-the-art methods on transmission line sag monitoring are thoroughly reviewed and compared. Both the direct methods that use the direct video or image of the transmission line and the indirect methods that use the relationships between sag and line parameters are investigated. Sag prediction methods and relevant industry standards are also examined. Based on these investigation and examination, future research challenges are outlined and useful recommendations on the choices of sag monitoring methods in different applications are made