Dynamic Monitoring of Structural Deformations utilizing an Experimentally Validated Efficient Technique

Up-to-date detection of a building's responses under various load situations is essential to generate data used to assess its capacity to bear crucial loads. This study presents an innovative and effective method to detect structural displacements and provide a more accurate alternative to existing approaches such as trigonometry leveling and angle intersecting. The least squares method was used to produce a concurrent solution that includes all the observed data to improve precision and retrieve the data needed for statistical analysis. The proposed method was validated experimentally and compared with the total station, conventional structural analysis, and displacement gauges to test and monitor a three-point loaded Reinforced Concrete (RC) beam at seven discrete points. The displacement gauge measurements were used as a baseline for comparing the outcomes from the other methods. The maximum mid-span deflection of the tested RC beam showed that the variation between the recorded displacement using displacement gauges and the suggested approach was below 0.31mm, resulting in a 3.7% inaccuracy, while the total station observations and the ACI-Code deflection provisions provided deflections of 0.62 and 3.64mm, resulting in 7.4% and 43.4% inaccuracies, respectively. Furthermore, comparing the results using root-mean-square error, the suggested method's precision in detecting displacements was much superior to the total station. The proposed approach was effective for detecting horizontal and vertical deformations and offers a viable option for building monitoring across both the element and whole building stages

Development of a Semi-autonomous Holonomic Load Carrier with Multi-camera Perception

Master's thesis in Mechatronics (MAS500)This thesis documents the development of a load carrier capable of carrying ten advanced personal robots. The robots of concern are Segway Robotics’ Loomo,which are used for education purposes at the University of Agder. They are used at multiple locations on campus, and it is desired to develop a system that can effectively transport them around. The report covers the concept generation, mechanical design, electrical design and development of a navigation system. A simple and compact design was developed and built. To achieve holonomic drive, the rig was equipped with four mecanum wheels. A mechanical design process was performed tocome up with a solution for mounting the wheels to the rig. This included design of an axle and bearing calculations. Additionally, the stability of the rig had to be verified. Further on,to drive the mecanum wheels, four brushless dc motors were utilized. The system consist of multiple hardware components, which needed to communicate with each other. The solution for this is documented in this report

Accuracy improvement in area-based matching for structural displacement measurements

Measuring and monitoring of structure deformations such as beams have an essential role in civil structural analysis. Measurements obtained pertaining to their displacements, among others, provide the information needed for the studies on material behaviours and structural designs. These measurements can also provide important indicators regarding to their failures. Under controlled laboratory conditions, these displacements can be determined using, for instance, high precision Linear Voltage Differential Transducers (LVDT). The high precision capabilities of these sensors make them suitable for structural deflection experiments. However, these LVDT sensors face a number of major drawbacks, such as, the sensors may be subjected to movement or damaged during the experiment, and the points measured are at pre-determined locations. In other words, displacements can only be measured at points where the LVDTs sensors are fixed. In addition, when large numbers of points of displacement are required or desired, the use of these sensors becomes prohibitively expensive and laborious. Whilst various researchers have used digital close range photogrammetry and the area-based matching approach in determining movements but work on the use of more than two images and surface models has not been reported. Therefore, this study proposes a revised method of precisely determining the displacements of structures using a multi-image area-based matching approach that uses surface models, i.e. a non-contact method. Experiments on beams under loading were performed under laboratory conditions. A series of multiple digital images were captured simultaneously using three digital single-lens reflex cameras throughout the experiments. The beam’s vertical displacements obtained from the proposed method were then validated by comparing against those obtained from the LVDTs. The results indicate that the mean differences between the displacement obtained from the proposed method and LVDTs are less than 0.5mm.The ttest conducted with a confidence level of 5% revealed that the differences between the two sets of results are not significant. It can be concluded that the use of multi-image area-based image matching using surface models is capable of measuring displacements and be used as an additional approach that complements the traditional methods in beam displacement measurements

Developing and testing a method for deformations measurements of structures

Dynamic monitoring of structures is an important task in civil engineering that aims to determine the stability and safety of a structure by using information about its deformations. This paper describes the development of a method for the determination of structures deformations. The proposed method is developed to add a new solution to traditional methods of angle intersection and trigonometric leveling. It is designed to provide a simultaneous solution to all observations in one step using least squares solution to improve the expected accuracy and to generate the necessary data for statistical analysis. A practical experiment was made, where the observations of 7 deformation points on a simply supported steel beam with concentrated load were measured using the proposed method, total station and linear variable displacement transducers (LVDTs). Deflections measured directly from LVDTs were used as a reference for assessment of the serviceability of the beam. The results show that for the maximum deflection at mid-span of the beam, the differences between the measured deflections from LVDTs and proposed method are less than 0.87 mm corresponding to an error of 4.3%, while they are less than 1.32 mm causing an error of 12.5% for the case of total station measurements. Based on root mean square error values, the accuracy of point displacements determination using the proposed method is much better than total station measurements. The proposed method is suitable for the accurate determination of horizontal and vertical displacements and provides a realistic solution for monitoring structures at both entire structure and member levels

3D modeling by low-cost range cameras: methods and potentialities

Nowadays the demand of 3D models for the documentation and visualization of objects and environments is continually increasing. However, the traditional 3D modeling techniques and systems (i.e. photogrammetry and laser scanners) can be very expensive and/or onerous, as they often need qualified technicians and specific post-processing phases. Thus, it is important to find new instruments, able to provide low-cost 3D data in real time and in a user-friendly way. Range cameras seem one of the most promising tools to achieve this goal: they are low-cost 3D scanners, able to easily collect dense point clouds at high frame rate, in a short range (few meters) from the imaged objects. Such sensors, though, still remain a relatively new 3D measurement technology, not yet exhaustively studied. Thus, it is essential to assess the metric quality of the depth data retrieved by these devices. This thesis is precisely included in this background: the aim is to evaluate the potentialities of range cameras for geomatic applications and to provide useful indications for their practical use. Therefore the three most popular and/or promising low-cost range cameras, namely the Microsoft Kinect v1, the Micorsoft Kinect v2 and the Occipital Structure Sensor, were firstly characterized from a geomatic point of view in order to assess the metric quality of the depth data retrieved by them. These investigations showed that such sensors present a depth precision and a depth accuracy in the range of some millimeters to few centimeters, depending both on the operational principle adopted by the single device (Structured Light or Time of Flight) and on the depth itself. On this basis, two different models were identified for precision and accuracy vs. depth: parabolic for the Structured Light (the Kinect v1 and the Structure Sensor) and linear for Time of Flight (the Kinect v2) sensors, respectively. Then the effectiveness of such accuracy models was demonstrated to be globally compliant with the found precision models for all of the three sensors. Furthermore, the proposed calibration model was validated for the Structure Sensor: with calibration, the overall RMSE, decreased from 27 to 16 mm. Finally four case studies were carried out in order to evaluate: • the performances of the Kinect v2 sensor for monitoring oscillatory motions (relevant for structural and/or industrial monitoring), demonstrating a good ability of the system to detect movements and displacements; • the integration feasibility of Kinect v2 with a classical stereo system, highlighting the need of an integration of range cameras into 3D classical photogrammetric systems especially to overpass limitations due to acquisition completeness; • the potentialities of the Structure Sensor for the 3D surveying of indoor environments, showing a more than sufficient accuracy for most applications; • the potentialities of the Structure Sensor to document archaeological small finds, where metric accuracy seems to be rather good while textured models shows some misalignments. In conclusion, although the experimental results demonstrated that range cameras have the capability to give good and encouraging results, the performances of traditional 3D modeling techniques in terms of accuracy and precision are still superior and must be preferred when the accuracy requirements are restrictive. But for a very wide and continuously increasing range of applications, when the required accuracy can be at the level from few millimeters (very close-range) to few centimeters, then range cameras can be a valuable alternative, especially when non expert users are involved. Furthermore, the technology on which these sensors are based is continually evolving, driven also by the new generation of AR/VR reality kits, and certainly also their geometric performances will soon improve

Engineering for a Changing World: 59th IWK, Ilmenau Scientific Colloquium, Technische Universität Ilmenau, September 11-15, 2017 : programme

In 2017, the Ilmenau Scientific Colloquium is again organised by the Department of Mechanical Engineering. The title of this year’s conference “Engineering for a Changing World” refers to limited natural resources of our planet, to massive changes in cooperation between continents, countries, institutions and people – enabled by the increased implementation of information technology as the probably most dominant driver in many fields. The Colloquium, complemented by workshops, is characterised by the following topics, but not limited to them: – Precision Engineering and Metrology – Industry 4.0 and Digitalisation in Mechanical Engineering – Mechatronics, Biomechatronics and Mechanism Technology – Systems Technology – Innovative Metallic Materials The topics are oriented on key strategic aspects of research and teaching in Mechanical Engineering at our university

Structural Health Monitoring using Unmanned Aerial Systems

The use of Structural Health Monitoring (SHM) techniques is paramount to the safety and longevity of the structures. Many fields use this approach to monitor the performance of a system through time to determine the proper time and funds associated with repair and replacement. The monitoring of these systems includes nondestructive testing techniques (NDT), sensors permanently installed on the structure, and can also rely heavily on visual inspection. Visual inspection is widely used due to the level of trust owners have in the inspection personnel, however it is time consuming, expensive, and relies heavily on the experience of the inspectors. It is for these reasons that rapid data acquisition platforms must be developed using remote sensing systems to collect, process, and display data to decision makers quickly to make well informed decisions based on quantitative data or provide information for further inspection with a contact technique for targeted inspection. The proposed multirotor Unmanned Aerial System (UAS) platform carries a multispectral imaging payload to collect data and serve as another tool in the SHM cycle. Several demonstrations were performed in a laboratory setting using UAS acquired imagery for identification and measurement of structures. Outdoor validation was completed using a simulated bridge deck and ground based setups on in service structures. Finally, static laboratory measurements were obtained using multispectral patterns to obtain multiscale deformation measurements that will be required for use on a UAS. The novel multiscale, multispectral image analysis using UAS acquired imagery demonstrates the value of the remote sensing system as a nondestructive testing platform and tool for SHM.Ph.D., Mechanical Engineering and Mechanics -- Drexel University, 201

Dynamical systems : mechatronics and life sciences

Proceedings of the 13th Conference „Dynamical Systems - Theory and Applications" summarize 164 and the Springer Proceedings summarize 60 best papers of university teachers and students, researchers and engineers from whole the world. The papers were chosen by the International Scientific Committee from 315 papers submitted to the conference. The reader thus obtains an overview of the recent developments of dynamical systems and can study the most progressive tendencies in this field of science

Engineering for a changing world: 60th Ilmenau Scientific Colloquium, Technische Universität Ilmenau, September 04-08, 2023 : programme

In 2023, the Ilmenau Scientific Colloquium is once more organised by the Department of Mechanical Engineering. The title of this year’s conference “Engineering for a Changing World” refers to limited natural resources of our planet, to massive changes in cooperation between continents, countries, institutions and people – enabled by the increased implementation of information technology as the probably most dominant driver in many fields. The Colloquium, supplemented by workshops, is characterised but not limited to the following topics: – Precision engineering and measurement technology Nanofabrication – Industry 4.0 and digitalisation in mechanical engineering – Mechatronics, biomechatronics and mechanism technology – Systems engineering – Productive teaming - Human-machine collaboration in the production environment The topics are oriented on key strategic aspects of research and teaching in Mechanical Engineering at our university