Institute of Fundamental Technological Research

Będkowski J., Benchmark of multi-view Terrestrial Laser Scanning Point Cloud data registration algorithms, MEASUREMENT, ISSN: 0263-2241, DOI: 10.1016/j.measurement.2023.113199, pp.113199-1-113199-55, 2023

Abstract:
This study addresses multi-view Terrestrial Laser Scanning Point Cloud data registration methods. Multiple rigid point cloud data registration is mandatory for aligning all scans into a common reference frame and it is still considered a challenge looking from a large-scale surveys point of view. The goal of this work is to support the development of cutting-edge registration methods in geoscience and mobile robotics domains. This work evaluates 3 data sets of total 20 scenes available in the literature. This paper provides a novel open-source framework for multi-view Terrestrial Laser Scanning Point Cloud data registration benchmarks. The goal was to verify experimentally which registration variant can improve the open-source data looking from the quantitative and qualitative points of view. In particular, the following scanners provided measurement data: Z+F TLS Imager 5006i, Z+F TLS Imager 5010C, Leica ScanStation C5, Leica ScanStation C10, Leica P40 and Riegl VZ-400. The benchmark shows an impact of the metric e.g. point to point, point to projection onto a plane, plane to plane etc..., rotation matrix parameterization (Tait-Bryan, quaternion, Rodrigues) and other implementation variations (e.g. multi-view Normal Distributions Transform, Pose Graph SLAM approach) onto the multi-view data registration accuracy and performance. An open-source project is created and it can be used for improving existing data sets reported in the literature, it is the added value of the presented research. The combination of metrics, rotation matrix parameterization and optimization algorithms creates hundreds of possible approaches. It is shown that chosen metric is a dominant factor in data registration. The rotation parameterization and other degrees of freedom of proposed variants are rather negligible compared with chosen metric. Most of the proposed approaches improve registered reference data provided by other researchers. Only for 2 from 20 scenes it was not possible to provide significant improvement. The largest improvements are evident for large-scale scenes. The project is available and maintained at https://github.com/MapsHD/HDMapping.

Keywords:
TLS,Point cloud,Open-source,Multi-view data registration,LiDAR data metrics,Robust loss function,Tait-bryan angles,Quaternions,Rodrigues’ formula,Lie algebra

Będkowski J., Benchmark of multi-view Terrestrial Laser Scanning Point Cloud data registration algorithms, MEASUREMENT, ISSN: 0263-2241, DOI: 10.1016/j.measurement.2023.113199, Vol.219, pp.1-28, 2023

Abstract:
This study addresses multi-view Terrestrial Laser Scanning Point Cloud data registration methods. Multiple rigid point cloud data registration is mandatory for aligning all scans into a common reference frame and it is still considered a challenge looking from a large-scale surveys point of view. The goal of this work is to support the development of cutting-edge registration methods in geoscience and mobile robotics domains. This work evaluates 3 data sets of total 20 scenes available in the literature. This paper provides a novel opensource framework for multi-view Terrestrial Laser Scanning Point Cloud data registration benchmarks. The goal was to verify experimentally which registration variant can improve the open-source data looking from
the quantitative and qualitative points of view. In particular, the following scanners provided measurement
data: Z+F TLS Imager 5006i, Z+F TLS Imager 5010C, Leica ScanStation C5, Leica ScanStation C10, Leica P40 and Riegl VZ-400. The benchmark shows an impact of the metric e.g. point to point, point to projection onto a plane, plane to plane etc..., rotation matrix parameterization (Tait–Bryan, quaternion, Rodrigues) and other implementation variations (e.g. multi-view Normal Distributions Transform, Pose Graph SLAM approach) onto the multi-view data registration accuracy and performance. An open-source project is created and it can be used for improving existing data sets reported in the literature, it is the added value of the presented research. The combination of metrics, rotation matrix parameterization and optimization algorithms creates
hundreds of possible approaches. It is shown that chosen metric is a dominant factor in data registration.
The rotation parameterization and other degrees of freedom of proposed variants are rather negligible compared with chosen metric. Most of the proposed approaches improve registered reference data provided by other researchers. Only for 2 from 20 scenes it was not possible to provide significant improvement. The largest improvements are evident for large-scale scenes. The project is available and maintained at https://github.com/MapsHD/HDMapping.

Keywords:
TLS, Point cloud, Open-source, Multi-view data registration, LiDAR data metrics, Robust loss function, Tait–Bryan angles, Quaternions, Rodrigues’ formula, Lie algebra, Rotation matrix parameterization

Groll W., Sowiński B., Konowrocki R., Study of transitional phenomena in rail vehicle dynamics in relation to the reliability and operational state of the continuous welded rail track in terms of rail joints, Eksploatacja i niezawodność, ISSN: 1507-2711, DOI: 10.17531/ein.2023.1.7, Vol.25, No.1, pp.1-11, 2023

Abstract:
This paper presents the results of experimental and numerical studies on reliability and monitoring issues of railway infrastructure in terms of safety and operation. The state of knowledge concerning methods of assessing track condition, in particular rail joints used in continuous welded rail track of railway lines is described. Experimental results of rail joints used in track transition zones and the results of numerical studies/tests of the rail vehicle-track model are outlined. It is demonstrated, basing on the analyses of the experimental results, that not only should the rail joints used in continuous welded rail track be diagnosed during their acceptance, but also during their operation. It is proven that the currently used methodology for testing welded rail joints applied during acceptance testing of contact track is not fully correct and leads to misinterpretation of the measurement results. Moreover, the results of numerical simulation tests presented in this paper confirm the possibility of diagnosing the condition of rail joints by any vehicle passing over such a track equipped with a suitable system.

Keywords:
operational safety,numerical and experimental studies,rail vehicle dynamics,continuous welded rail track,operational safety

Żurawski M., Graczykowski C., Zalewski R., The prototype, mathematical model, sensitivity analysis and preliminary control strategy for Adaptive Tuned Particle Impact Damper, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2023.117799, Vol.564, No.117799, pp.1-32, 2023

Abstract:
The paper presents a novel approach for prototyping and modelling of the Adaptive Tuned Particle Impact Damper (ATPID). After introducing the operation and potential disadvantages of the classical Particles Impact Dampers (PIDs) the authors propose the concept of single-grain controllable damper, which can adapt to actual dynamic excitation by a real-time change of the container height. The investigations focus on the methodology of simplified mathematical modelling of the ATPID damper based on grain physical properties, nonlinear soft contact theory, and control function of the absorber height being a novel component used to optimize dynamic response of the system. The proposed ATPID model is positively verified against the experimental results obtained from the developed test stand including a vibrating beam equipped with the proposed innovative attenuator. The conducted analyses clearly reveal the operating principles of the ATPID damper, the types of grain movement, the influence of shock absorber parameters on the vibrating system response and the energy balance of the system. The solution of the formulated optimization problem aimed at minimization of vibration amplitudes allows to find the optimal damper height for various physical parameters of the grain and the external excitation and to achieve a high efficiency of the proposed damper reaching 90%. In addition, a real-time control strategy providing adaptation of the ATPID damper to changing amplitude of kinematic excitation and effective mitigation of steady-state vibrations is proposed and verified experimentally.

Keywords:
Adaptive Tuned Particle Impact Damper, Damping of vibrations, Semi-active damping, Controllable damper, Control function, Sensitivity analysis, System optimization, Real-time control strategy

Ostrowski M., Mikułkowski G., Błachowski B., Jankowski Ł., Experimental assessment of Bayesian and mode matching approaches for parametric identification of bolted connections, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2023.110652, Vol.201, pp.110652-110652, 2023

Abstract:
This paper investigates the problem of parametric identification of highly uncertain bolted connections. The unknown parameters representing stiffness of the connections are estimated using two commonly accepted methods: (1) the traditional mode matching approach and (2) a probabilistic Bayesian framework based on the maximum a posteriori (MAP) formulation. Additionally, the uncertainties of the unknown parameters are also estimated and compared for both methods. A numerical example and a real lab-scale frame structure with highly uncertain bolted connections were used in the tests. In the experimental case, the system eigenvalues (squares of the natural frequencies) and the mode shapes measured in a broad frequency range were employed. The measured mode shapes were strongly disturbed by assembly discrepancies of the bolted connections. Finally, both methods were compared in terms of computational efficiency on a large-scale FE model (31,848 degrees of freedom). Despite the sophistication of the Bayesian approach in treating the trade-off between measurement errors and expected modeling errors, the results indicate that the two tested methods yield similar values for the unknown parameters. The Bayesian approach requires numerical regularization to calculate the parameter covariance matrix, which may decrease its reliability. In contrast, the mode matching method avoids such numerical difficulties. Furthermore, the Bayesian approach requires a much larger number of iterations and a careful selection of the weighting parameters.

Keywords:
Mode matching, Bayesian approach, Parametric identification, Uncertain bolted connections, Parameter uncertainty, Convergence

Dyniewicz B., Bajkowski J. M., Bajer C., Efficient Strategy for Space-Time Based Finite Element Analysis of Vibrating Structures, Computers & Mathematics with Applications, ISSN: 1873-7668, DOI: 10.1016/j.camwa.2023.08.002, Vol.148, pp.70-80, 2023

Abstract:
This paper presents an efficient parallel computing strategy to solve large-scale structural vibration problems. The proposed approach utilises a novel direct method that operates using simplex-shaped space-time finite elements and allows for the direct decoupling of variables during the assembly of global matrices. The method uses consistent stiffness, inertia and damping matrices and deals with non-symmetric matrices. One significant advantage of this approach is that the computational cost remains unaffected by the bandwidth of the matrix in the traditional sense because only non-zero coefficients are retained. The speed of computations demonstrates a noticeable increase as the number of nodes and the problem's dimensionality grow. To demonstrate the effectiveness of the parallel space-time approach, a comparison with a sequentially executed code was conducted. The results indicate that the proposed method enables calculations at least 20 times faster than those achieved using the classical finite element method. Furthermore, the parallelisation algorithm was successfully implemented to solve a dynamics problem involving a large-scale, three-dimensional railway structure subjected to a moving load. Remarkably, the problem was solved in a reasonable amount of time using a relatively low-cost personal computer.

Keywords:
Space-time, Finite element, Direct decoupling, Vibration, Moving load, Parallel algorithm

Pisarski D., Jankowski , Reinforcement learning-based control to suppress the transient vibration of semi-active structures subjected to unknown harmonic excitation, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12920, Vol.38, No.12, pp.1605-1621, 2023

Abstract:
The problem of adaptive semi-active control of transient structural vibration induced by unknown harmonic excitation is studied. The controller adaptation is attained by using a specially designed reinforcement learning algorithm that adjusts the parameters of a switching control policy to guarantee efficient dissipation of the structural energy. This algorithm relies on an efficient gradient-based sequence that accelerates the learning protocol and results in suboptimal control. The performance of this method is examined through numerical experiments for a span structure that is equipped with a semi-active device of controlled stiffness and damping parameters. The experiments cover a selection of control learning scenarios and comparisons to optimal open-loop and heuristic state-feedback control strategies. This study has confirmed that the developed method has high stabilizing performance, and the relatively low computational burden of the incorporated iterative learning algorithm facilitates its application to multi–degree-of-freedom structures.

Keywords:
reinforcement learning,semi-active control,optimisation,vibration suppression,bilinear system

Badora M., Bartosik P., Graziano A., Szolc T.A., Using physics-informed neural networks with small datasets to predict the length of gas turbine nozzle cracks, Advanced Engineering Informatics, ISSN: 1474-0346, DOI: 10.1016/j.aei.2023.102232, Vol.58, No.102232, pp.1-16, 2023

Abstract:
We created a Physics-Informed Neural Network (PINN) to model the propagation of fatigue cracks. The analyzed object is a high-pressure Nozzle of an industrial gas turbine. The models are based on a Recurrent Neural Network with an embedded Feedforward Neural Network to estimate the stress intensity factor. The thermal stresses are calculated based on engine operational data, leveraging a Finite Element Analysis. However, the time series are available just for 54% of the start-stop cycles, and only 13 crack measures were recorded. Three separate models were trained based on ten, two, and one observation, respectively. The importance of the empirical data was regulated during the training to avoid solutions inconsistent with the underlying physics. The models generalize well and predict accurately also outside the training domain. Additionally, we propose a novel method of scaling models based on PINNs and transferring knowledge between domains. It enables predicting in the target domain, even if damage measures are unavailable. The obtained results confirm the effectiveness of this approach.

Keywords:
Physics-informed neural networks , Predictive maintenance , Fatigue cracks , Regression analysis , Small data , Turbomachinery

Alaei A., Hejazi M., Vintzilaiou E., Miltiadou-Fezans A., Skłodowski M., Dynamic identification of brick masonry semi-circular arches due to temperature and moisture, Structures, ISSN: 2352-0124, Vol.50, pp.148-160, 2023

Abstract:
This paper presents the effects of changes in temperature and moisture content on the dynamic properties of semi-circular arches made of clay brick and gypsum mortar constructed and tested in the laboratory. First, the mechanical properties of the materials used were determined by experimental tests. Operational Modal Analysis was then performed for each condition to measure natural frequencies, mode shapes, and modal damping ratios. An empirical equation for estimating the natural frequencies of the studied arch at different material moisture contents was proposed using the obtained results from experimental tests. Finally, the Finite Element Model Updating Method (FEMU) was applied to calibrate some of the material mechanical properties in modelled arches. In contrast to the effect of moisture, temperature changes showed a difficulty to interpret effect on the dynamic properties of the arch. On the other hand, Poisson's ratio did not affect the dynamic behaviour of the specimen.

Keywords:
Operational Modal Analysis, Brick Masonry Semi-Circular Arch, Temperature, Moisture, Dynamic Parameters

Działak P., Syczewski Marcin D., Błachowski A., Kornaus K., Bajda T., Zych , Osial M., Borkowski A.^♦, Surface modification of magnetic nanoparticles by bacteriophages and ionic liquids precursors, RSC Advances, ISSN: 2046-2069, DOI: 10.1039/d2ra06661k, Vol.13, pp.926-936 , 2023

Abstract:
Magnetic nanoparticles (MNPs) have recently been a point of interest for many researchers due to their properties. However, the studies on the influence of bacteriophages on the synthesis of MNPs seem to be lacking. Furthermore, bacteriophage-modified MNPs have not been combined with n-alkyl quaternary ammonium ionic liquid precursors (QAS). In this study, the aim was to assess the influence of two distinctly different bacteriophages (Escherichia phage P1 and Pseudomonas phage Φ6) on MNPs synthesis in the presence or absence of QAS. Synthesized MNPs have been characterized with X-ray diffraction (XRD) and Mössbauer spectroscopy in terms of changes in the crystallographic structure; scanning electron microscopy (SEM) for changes in the morphology; and ζ-potential. Moreover, the sorption parameters and the loss of viability of bacteria that interacted with MNPs have been determined. The sorption of bacteria differs significantly among the tested samples. Furthermore, the viability of the bacteria adsorbed on MNPs varies in the presence of QAS, depending on the length of the n-alkyl chain. The study has revealed that MNPs can be bound with bacteriophages. Mössbauer spectroscopy has also revealed the probable influence of bacteriophages on the formation of crystals. However, these phenomena require further studies.

Niemczyk-Soczyńska B., Kołbuk-Konieczny D., Mikułowski G., Ciechomska I.A., Sajkiewicz P.Ł., Methylcellulose/agarose hydrogel loaded with short electrospun PLLA/laminin fibers as an injectable scaffold for tissue engineering/3D cell culture model for tumour therapies, RSC Advances, ISSN: 2046-2069, DOI: 10.1039/D3RA00851G, Vol.13, No.18, pp.11889-11902, 2023

Abstract:
This research aimed at designing and fabricating a smart thermosensitive injectable methylcellulose/agarose hydrogel system loaded with short electrospun bioactive PLLA/laminin fibers as a scaffold for tissue engineering applications or 3D cell culture models. Considering ECM-mimicking morphology and chemical composition, such a scaffold is capable of ensuring a hospitable environment for cell adhesion, proliferation, and differentiation. Its viscoelastic properties are beneficial from the practical perspective of minimally invasive materials that are introduced to the body via injection. Viscosity studies showed the shear-thinning character of MC/AGR hydrogels enabling the potential injection ability of highly viscous materials. Injectability tests showed that by tuning the injection rate, even a high amount of short fibers loaded inside of hydrogel could be efficiently injected into the tissue. Biological studies showed the non-toxic character of composite material with excellent viability, attachment, spreading, and proliferation of fibroblasts and glioma cells. These findings indicate that MC/AGR hydrogel loaded with short PLLA/laminin fibers is a promising biomaterial for both tissue engineering applications and 3D tumor culture models.

Szemela K., Meissner M.W., Rdzanek W.P., Efficient analytical method for computing the acoustic field inside enclosures with a mixed rectangular-cylindrical geometry, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2022.109182, Vol.202, No.109182, pp.1-12, 2023

Abstract:
Enclosures with a mixed rectangular-cylindrical geometry are common in sacred, historic and modern buildings. Therefore, obtaining efficient analytical formulas for describing the sound radiation inside such structures is of practical importance. These formulas can be implemented in open-source software and can aid in the analysis of acoustic fields. In this study, the problem of sound radiation by a point source located inside a rectangular enclosure with a sound-absorbing quarter-cylindrical ceiling was analytically solved. The formulas presented in this paper can also be used to obtain the eigenfrequencies and eigenfunctions. To obtain the analytical solution, two connected subregions, namely rectangular space, and quarter-cylinder, were considered, and the continuity conditions were imposed on the region’s coupling interface. The acoustic field was described using the solution for a rigid-walled room and the additional components containing the Fourier and Dini series. These components allow the solution to satisfy the impedance boundary condition and the continuity conditions. The formulas and their computer implementation were validated using the finite element method (FEM). A good agreement was achieved between results given by both methods. The numerical analysis demonstrated that the use of the formulas is less time-consuming than using FEM when the frequency is greater than 150 Hz. Moreover, compared to FEM, the analytical solution can be applied to higher frequencies for which the use of FEM requires hardware with high computing capability.

Keywords:
Room acoustics,Irregular enclosure,Efficient analytical solution,Acoustic pressure field,Acoustic intensity vector field,Complex eigenfrequencies

Ostrowski M., Błachowski B., Mikułowski G., Jankowski Ł., Influence of Noise in Computer-Vision-Based Measurements on Parameter Identification in Structural Dynamics, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s23010291, Vol.23, No.1, pp.1-27, 2023

Abstract:
Nowadays, consumer electronics offer computer-vision-based (CV) measurements of dynamic displacements with some trade-offs between sampling frequency, resolution and low cost of the device. This study considers a consumer-grade smartphone camera based on complementary metal-oxide semiconductor (CMOS) technology and investigates the influence of its hardware limitations on the estimation of dynamic displacements, modal parameters and stiffness parameters of bolted connections in a laboratory structure. An algorithm that maximizes the zero-normalized cross-correlation function is employed to extract the dynamic displacements. The modal parameters are identified with the stochastic subspace identification method. The stiffness parameters are identified using a model-updating technique based on modal sensitivities. The results are compared with the corresponding data obtained with accelerometers and a laser distance sensor. The CV measurement allows lower-order vibration modes to be identified with a systematic (bias) error that is nearly proportional to the vibration frequency: from 2% for the first mode (9.4 Hz) to 10% for the third mode (71.4 Hz). However, the measurement errors introduced by the smartphone camera have a significantly lower influence on the values of the identified stiffness parameters than the numbers of modes and parameters taken into account. This is due to the bias–variance trade-off. The results show that consumer-grade electronics can be used as a low-cost and easy-to-use measurement tool if lower-order modes are required.

Keywords:
computer vision,smartphone camera,system identification,model updating,uncertain bolted connections

Będkowski J., Pełka M., Affordable Robotic Mobile Mapping System Based on Lidar with Additional Rotating Planar Reflector, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s23031551, Vol.23, No.3, pp.1-19, 2023

Abstract:
This paper describes an affordable robotic mobile 3D mapping system. It is built with Livox Mid−40 lidar with a conic field of view extended by a custom rotating planar reflector. This 3D sensor is compared with the more expensive Velodyne VLP 16 lidar. It is shown that the proposed sensor reaches satisfactory accuracy and range. Furthermore, it is able to preserve the metric accuracy and non−repetitive scanning pattern of the unmodified sensor. Due to preserving the non−repetitive scan pattern, our system is capable of covering the entire field of view of 38.4 × 360 degrees, which is an added value of conducted research. We show the calibration method, mechanical design, and synchronization details that are necessary to replicate our system. This work extends the applicability of solid−state lidars since the field of view can be reshaped with minimal loss of measurement properties. The solution was part of a system that was evaluated during the 3rd European Robotics Hackathon in the Zwentendorf Nuclear Power Plant. The experimental part of the paper demonstrates that our affordable robotic mobile 3D mapping system is capable of providing 3D maps of a nuclear facility that are comparable to the more expensive solution.

Keywords:
automatic calibration, solid-state lidar, reshape field of view, 3D mapping, SLAM, robotic mapping

Będkowski J., Pełka M., Affordable Robotic Mobile Mapping System Based on Lidar with Additional Rotating Planar Reflector , SENSORS, ISSN: 1424-8220, DOI: 0.3390/s23031551, Vol.23(3), No.1551, pp.1-19, 2023

Abstract:
This paper describes an affordable robotic mobile 3D mapping system. It is built with Livox Mid–40 lidar with a conic field of view extended by a custom rotating planar reflector. This 3D sensor is compared with the more expensive Velodyne VLP 16 lidar. It is shown that the proposed sensor reaches satisfactory accuracy and range. Furthermore, it is able to preserve the metric accuracy and non–repetitive scanning pattern of the unmodified sensor. Due to preserving the non–repetitive scan pattern, our system is capable of covering the entire field of view of 38.4 × 360 degrees, which is an added value of conducted research. We show the calibration method, mechanical design, and synchronization details that are necessary to replicate our system. This work extends the applicability of solid–state lidars since the field of view can be reshaped with minimal loss of measurement properties. The solution was part of a system that was evaluated during the 3rd European Robotics Hackathon in the Zwentendorf Nuclear Power Plant. The experimental part of the paper demonstrates that our affordable robotic mobile 3D mapping system is capable of providing 3D maps of a nuclear facility that are comparable to the more expensive solution.

Keywords:
automatic calibration,solid-state lidar,reshape field of view,3D mapping,SLAM,robotic mapping

Graczykowski C., Faraj R., Adaptive Impact Mitigation Based on Predictive Control with Equivalent Mass Identification, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s23239471, Vol.23, No.3, pp.9471-1-31, 2023

Abstract:
The paper presents the concept of equivalent parameter predictive control (EPPC) elaborated for semi-active fluid-based (hydraulic and pneumatic) shock absorbers equipped with controllable valves and subjected to impact excitation. The undertaken problem concerns the absorption and dissipation of the impact energy with the requirement to minimize the generated reaction force and corresponding impacting object deceleration. The development of a control strategy for a challenging problem with unknown impacting object mass and unknown changes of external and disturbance forces is proposed and discussed in detail. The innovative solution utilizes the paradigm of model
predictive control supplemented by the novel concept of equivalent system parameters identification. The EPPC is based on the online measurement of system response, the computation of the equivalent
mass of the impacting object, and the repetitive solution of the optimal control problem with various prediction intervals and constraints imposed on valve opening. The presented method is proven to operate robustly for unknown excitations, including double-impact conditions, and it has similar efficiency to control methods developed previously for known impact parameters.

Keywords:
adaptive impact absorption, semi-active control, self-adaptive shock absorber, adaptive model predictive control, model identification adaptive control, model predictive control

Holnicki-Szulc J., Wagg D., Casciati F., Faravelli L., Jankowski Ł., Recent advances in structural control and health monitoring, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.24425/bpasts.2023.145764, Vol.71, No.3, pp.e145764-1-e145764-3, 2023

Keywords:
EACS 2022, structural control, structural health monitoring

Graczykowski C., Faraj R., Extended Identification-Based Predictive Control for adaptive impact mitigation, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.24425/bpasts.2023.145937, Vol.71, No.4, pp.145937-1-10, 2023

Abstract:
The paper introduces Extended Identification-Based Predictive Control (EIPC), which is a novel control method developed for the problem of adaptive impact mitigation. The model-based approach utilizing the paradigm of Model Predictive Control is combined with sequential identification of selected system parameters and process disturbances. The elaborated method is implemented in the shock-absorber control system and tested under impact loading conditions. The presented numerical study proves the successful and efficient adaptation of the absorber to unknown excitation conditions as well as to unknown force and leakage disturbances appearing during the process. The EIPC is used for both semi-active and active control of the impact mitigation process, which are compared in detail. In addition, the influence of selected control parameters and disturbance identification on the efficiency of the impact absorption process is assessed. As a result, it can be concluded that an efficient and robust control method was developed and successfully applied to the problem of adaptive impact mitigation.

Keywords:
adaptive control,optimal control,predictive control,impact mitigation,shock absorber

Hańczur P., Szolc T.A., Konowrocki R., Suppression of rotating machine shaft-line torsional vibrations by a driving asynchronous motor using two advanced control methods, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: DOI: 10.24425/bpasts.2023.147925, Vol.71, No.6 ( e147925 ), pp.1-13, 2023

Abstract:
Many industrial rotating machines driven by asynchronous motors are often affected by detrimental torsional
vibrations. In this paper a method of attenuation of torsional vibrations in such objects is proposed. Here, an asynchronous motor
under a proper control can simultaneously operate as a source of drive and actuator. Namely, by means of the proper control of
motor operation it is possible to suppress torsional vibrations in the object under study. Using this approach, transient and steady-
state torsional vibrations of the rotating machine drive system can be effectively attenuated as well as its precise operational
motions can be assured. The theoretical investigations are carried out by means of a structural mechanical model of the drive
system and an advanced circuit model of the asynchronous motor controlled using two methods: the direct torque control – space
vector modulation (DTC-SVM) and the rotational velocity controlled torque (RVCT) based on the momentary rotational velocity
of the driven machine working tool. From the obtained results it follows that by means of the RVCT technique steady-state
torsional vibrations induced harmonically and transient torsional vibrations excited by switching various types of control on and
off can be suppressed as effectively as using the advanced vector method DTC-SVM.

Keywords:
rotating machine,drive system,control methods,asynchronous motor,torsional vibrations

Zawidzka E., Zawidzki M., Simulation of simple movements of Arm-Z oblique swivel joint chain manipulator, POMIARY - AUTOMATYKA - ROBOTYKA. PAR, ISSN: 1427-9126, DOI: 10.14313/PAR_248/59, Vol.27, No.2, pp.59-67, 2023

Abstract:
Arm-Z is a concept of a hyper-redundant manipulator based on linearly joined sequence of congruent modules by oblique swivel joint mechanism. Each module has one degree of freedom only, namely a twist relative to the previous module in the sequence. Although the concept of this type of manipulator is relatively old and simple, its control is very difficult an nonintuitive, which results in a limited use in industrial practice. This paper presents a simple simulation of Arm-Z in Mathematica programming environment which demonstrates a few simple but potentially useful movements.

Keywords:
Arm-Z, Extremely Modular System, hyper-redundant manipulator, Mathematica, oblique swivel joint

Zawidzka E., Zawidzki M., Kiński W., Prototyp ekstremalnie modularnego hiperredundantnego manipulatora Arm-Z, POMIARY - AUTOMATYKA - ROBOTYKA. PAR, ISSN: 1427-9126, DOI: 10.14313/PAR_247/39, Vol.27, No.1, pp.39-44, 2023

Abstract:


Arm-Z to koncepcja hiperredundantnego manipulatora robotycznego składającego się z przystających modułów o jednym stopniu swobody (1-DOF) i realizującego (prawie) dowolne ruchy w przestrzeni. Zasadnicze zalety Arm-Z to: ekonomizacja (dzięki masowej produkcji identycznych elementów) oraz odporność na awarie (po pierwsze – zepsute moduły mogą być łatwo zastąpione, po drugie – nawet gdy jeden lub więcej modułów ulegnie awarii – manipulator taki może ciągle wykonywać, prawdopodobnie w stopniu ograniczonym, zakładane zadania). Podstawową wadą systemu Arm-Z jest jego nieintuicyjne, bardzo trudne sterowanie. Innymi słowy, połączenie koncepcji nietrywialnego modułu z formowaniem praktycznych konstrukcji oraz sterowanie ich rekonfiguracją (transformacją ze stanu A do B) są bardzo złożone obliczeniowo. Mimo to prezentowane podejście jest racjonalne, zważywszy powszechną dostępność wielkich mocy obliczeniowych w kontraście z wysokimi kosztami i „delikatnością” niestandardowych rozwiązań i urządzeń. W artykule nakreślono ogólną koncepcję manipulatora Arm-Z i zaprezentowano wstępne prace zmierzające do wykonania prototypu.

Keywords:
Arm-Z, odporność na awarie, sterowanie kształtem ogólnym, systemy modularne

Ostrowski M., Błachowski B., Wójcik B., Żarski M., Tauzowski P., Jankowski Ł., A framework for computer vision-based health monitoring of a truss structure subjected to unknown excitations, Earthquake Engineering and Engineering Vibration, ISSN: 1993-503X, DOI: 10.1007/s11803-023-2154-3, pp.1-17, 2023

Abstract:
Computer vision (CV) methods for measurement of structural vibration are less expensive, and their application is more straightforward than methods based on sensors that measure physical quantities at particular points of a structure. However, CV methods produce significantly more measurement errors. Thus, computer vision-based structural health monitoring (CVSHM) requires appropriate methods of damage assessment that are robust with respect to highly contaminated measurement data. In this paper a complete CVSHM framework is proposed, and three damage assessment methods are tested. The first is the augmented inverse estimate (AIE), proposed by Peng et al. in 2021. This method is designed to work with highly contaminated measurement data, but it fails with a large noise provided by CV measurement. The second method, as proposed in this paper, is based on the AIE, but it introduces a weighting matrix that enhances the conditioning of the problem. The third method, also proposed in this paper, introduces additional constraints in the optimization process; these constraints ensure that the stiff ness of structural elements can only decrease. Both proposed methods perform better than the original AIE. The latter of the two proposed methods gives the best results, and it is robust with respect to the selected coefficients, as required by the algorithm.

Keywords:
computer vision,structural health monitoring,physics-based graphical models,augmented inverse estimate,model updating,non-negative least square method

Alaei A., Hejazi M., Vintzileou E., Miltiadou-Fezans A., Skłodowski M., Effect of damage and repair on the dynamic properties of Persian brick masonry arches, The European Physical Journal Plus, ISSN: 2190-5444, DOI: 10.1140/epjp/s13360-023-03781-0, Vol.138, pp.231-243, 2023

Abstract:
In this paper, the dynamic properties of three types of Persian brick masonry arches, semi-circular, ordinary pointed and ordinary four-centred have been studied. These arches were constructed with clay brick, and gypsum mortar in the laboratory and experimental tests were conducted. First, the mechanical properties of the used materials were determined. Then, operational modal analysis was used to measure the dynamic properties of the constructed arches. Afterwards, a horizontal displacement was applied to the arch support to create a crack. The arches were repaired then, and dynamic identification was performed for each case. Several damage detection methods were used to evaluate their ability to detect damage in brick masonry arches. Finite element model updating was used to track changes in the material properties of arches and to match numerical results with dynamic laboratory results. The study showed that damage has a significant effect on the dynamic properties of arches. Repairing the damage partially restores the dynamic parameters to the undamaged condition, but it cannot completely transform the arch into an arch without damage. Damage detection methods were able to identify the occurrence of damage to the arches, but there are limitations in the use of these methods. Diagrams were generated to estimate the static moduli of brick and of gypsum mortar from the dynamic modulus of elasticity of the assemblage of brick and gypsum mortar.

Ostrowski M., Jedlińska A., Popławski B., Błachowski B., Mikułowski G., Pisarski D., Jankowski , Sliding Mode Control for Semi-Active Damping of Vibrations Using On/Off Viscous Structural Nodes, Buildings, ISSN: 2075-5309, DOI: 10.3390/buildings13020348, Vol.13, No.2, pp.1-16, 2023

Abstract:
Structural vibrations have adverse effects and can lead to catastrophic failures. Among various methods for mitigation of vibrations, the semi-active control approaches have the advantage of not requiring a large external power supply. In this paper, we propose and test a sliding mode control method for the semi-active mitigation of vibrations in frame structures. The control forces are generated in a purely dissipative manner by means of on/off type actuators that take the form of controllable structural nodes. These nodes are essentially lockable hinges, modeled as viscous dampers, which are capable of the on/off control of the transmission of bending moments between the adjacent beams. The control aim is formulated in terms of the displacement of a selected degree of freedom. A numerically effective model of such a node is developed, and the proposed control method is verified in a numerical experiment of a four-story shear structure subjected to repeated random seismic excitations. In terms of the root-mean-square displacement, the control reduced the response by 48.4-78.4% on average, depending on the number and placement of the applied actuators. The peak mean amplitude at the first mode of natural vibrations was reduced by as much as 70.6-96.5%. Such efficiency levels confirm that the proposed control method can effectively mitigate vibrations in frame structures.

Keywords:
semi-active control,sliding mode control,structural control,controllable nodes,on/off nodes,damping of vibrations

Zhao D., Dyniewicz B., Bajer C.I., Smart Elastic Material with a Moving Local Stiffness Zone for Reducing the Effects of Impact Loading, SHOCK AND VIBRATION, ISSN: 1070-9622, DOI: 10.1155/2023/6698248, Vol.2023, pp.1-10, 2023

Abstract:
The elastic material properties which change momentarily and locally under the high deformation rate due to the movement of a wavefront are presented. The work contains mathematical formulation, semianalytical results, numerical formulations, and simulation results demonstrating the effectiveness of modifying the rheological properties of the elastic material upon shock load or contact with a rigid obstacle. While the semianalytical solutions can be obtained in a narrow time interval, numerical solutions allow us to track the process of wavefront reflections from edges. The effectiveness of reducing the physical quantities significant for impact in the presented examples reaches 30–70% of forces or accelerations, depending on the adopted criteria.