Moire Method Research Articles

Automatic Detection Method of Camera Direction from Target Normal Direction in Sampling Moire Method and its Application to Displacements Measurement of Large Structures

Automatic Detection Method of Camera Direction from Target Normal Direction in Sampling Moire Method and its Application to Displacements Measurement of Large Structures

Impact of Standing and Sitting Postures on Spinal Curvature and Muscle Mechanical Properties in Young Women: A Photogrammetric and MyotonPro Analysis.

BACKGROUND This study aimed to evaluate the effect of standing and sitting positions on spinal curvatures evaluated using projection moire and muscle tone and stiffness using the MyotonPRO hand-held device in young women. MATERIAL AND METHODS Thirty-three healthy women, aged 21 to 23 years, volunteered in the study. We used the projection moire method to examine spinal curvatures in both positions and the MyotonPRO device to measure the tone and stiffness of muscles in 3 regions. We evaluated the effects of positions (standing vs sitting), regions (cervical, thoracic, and lumbar), and side factor (right vs left) using multivariate analysis. RESULTS The sitting position significantly decreased the lumbosacral and thoracolumbar angles (P<0.001), but had no effect on the superior thoracic angle. Muscle tension and stiffness were the highest (P<0.001) in the cervical region and did not differ between positions (P>0.05) in this region. We found significantly higher muscle tone and stiffness in the thoracic and lumbar regions during sitting than during standing (P<0.001). There was symmetry in the muscle tone and the stiffness between the right and left sides of the spine. CONCLUSIONS The sitting posture decreased lumbosacral and thoracolumbar angles but increased muscle tension and stiffness in the lumbar and thoracic regions only. The symmetry of muscle tone and transverse stiffness in both positions was the normative value. This study provides insight into the adaptive physiological changes in spinal curvature and muscle mechanical properties in young women and serves as an important reference point for clinical studies of women.

The Impact of Interaction between Body Posture and Movement Pattern Quality on Injuries in Amateur Athletes.

Background: this study aimed to examine the impact of interaction between body posture and the quality of movement patterns on injury frequencies in amateur athletes. Methods: The study sample consisted of 89 young amateur athletes. Movement pattern quality was assessed by the Functional Movement Screen (FMS), test and body posture in the frontal plane was assessed by the moire method for the parameters Shoulder Slope Angle, Lower Scapula Protrusion Difference, and Pelvic Tilt Angle. Injury data were collected through completion of the Injury History Questionnaire for the past 12 months. Results: Using cluster analysis, participants were allocated into a either category with good (BPg) body posture or poor (BPp), and using FMS cutoff points (14), either a category of good movement pattern quality (MPg) or poor (MPp). Two-way ANOVA was performed, and the Bonferroni post-hoc test revealed a reduction in injuries among participants from the MPg-BPg group compared to the other three groups (p < 0.05). However, no interaction between factors was revealed. No statistically significant differences were observed among the remaining three groups in the case of injury prevalence (p > 0.05). Conclusions: A combination of proper body posture and high-quality movement patterns is associated with a lower frequency of injuries, without direct interaction between chosen factors, which suggests that they impact injury risk independently. Practicing suitable BP and ensuring high-quality MPs should be regarded as a strategy in injury prevention.

쌍안경식 로드셀의 실험적 방법과 수치적 방법을 통한 변형 비교

In this paper, the structure and merits of the binocular type load cell are mentioned, and the principle of deformation of the load cell is assumed to be the deformation behavior of Statically indeterminate, and then theoretically analyzed. In addition, finite element analysis was conducted to determine the suitability of the principle and bending strain was measured. In order to compare this theory through actual experiments, an experimental method of measuring strain by attaching a strain gauge was conducted, and an additional optical analysis was performed. Through the shadow moire experiment, which is a technique, it was possible to draw conclusions by conducting comparisons with numerical methods. As a result of this analysis, the theory and finite element analysis showed an error of about 6.75%, and the basis for assuming negative information was given. have derived However, the shadow moire method showed a difference when compared to the numerical method, and these causes were analyzed and concluded.

Assessment of changes in the sagittal plane of the spine in girls with adolescent idiopathic scoliosis using the moire method.

The gold standard in the clinical assessment of the extent of scoliosis is the Cobb method but the analysis also covers the changes that occur within the spine and trunk in relation to the transverse and sagittal planes. The study aimed to estimate changes in the sagittal plane of the spine in girls with right-sided thoracic adolescent idiopathic scoliosis. The study involved 29 girls with scoliosis (13.6 ± 0.6 years) and 36 healthy girls as the comparison group. The tests included an interview, clinical examination (with the use of Adam's test and the Cobb angle), and examination of shape of the spine surface with the use of the photogrammetric method and the projection moire effect. Lower values of the thoracic kyphosis parameters were found in the scoliosis group. Significant differences were noted for the parameters of the lumbosacral section α (p= 0.02), thoracolumbar section β (p< 0.001), the upper thoracic section γ (p< 0.001), thoracolumbar and upper thoracic section β+γ (p< 0.001) and the total size of α+β+γ (p< 0.001) curvatures. The study showed that with an increase in the angular value of the thoracic curvature, the thoracic kyphosis decreased.

Multiplication sampling moire method for full-field deformation measurement of composite materials.

A multiplication sampling moire (MSM) method was proposed for robust deformation distribution measurement by performing phase analysis of the second harmonic (second-order frequency) of a single grating pattern. The MSM method has a very strong noise immunity because the second harmonic spectrum is far from the low-frequency region of the background noise in the frequency domain. Phase analysis of an experimental grid image on a carbon fiber-reinforced plastic (CFRP) specimen indicated that the MSM method effectively solved the problem of non-negligible phase measurement errors of conventional methods that extract the fundamental frequency of the grating, in the case of severe local noise. The displacement and strain distributions of CFRP in a tensile test were successfully measured. This method is suitable for deformation measurement of various composite materials.

Važiavimo metodų galulaukėje, naudojant telemetrines sistemas, tyrimas

This paper is a full article on the basis of the material presented in the two conference thesis. In the process of investigation of dynamics and vibrations of agricultural machines various experimental methods are used. Among them moire methods can be noted because of their simplicity and easy applicability. Projection moire is most often used for this purpose. It is used to visually estimate the shape of the eigenmode by projecting moire grating to a flat part of the case of the agricultural machine. Time averaging is applied when investigating vibrations of the structure according to the eigenmode. In this paper possibilities of application of hybrid experimental – numerical procedures for measurements of large amplitude vibrations by reflection moire are investigated.

Micro-deformation Study of Stainless Steel Impacted by Ceramic Particle Using Electron Moiré Method

High-velocity oxy-fuel (HVOF)-sprayed metallic coating can be used to create a surface layer that plays a significant role in enhancing the overall strength, stiffness, and fatigue life of the treated material. The micro-deformation around a single impacted particle is a critical factor that must be considered for the optimization of the HVOF process. In this study, the micro-deformation field of stainless steel impacted by a ceramic particle was characterized at the micro-scale. A grid with a frequency of 1200 lines/mm was fabricated on the surface of stainless steel specimen. The microscopic deformation field formed on the substreate surface, induced by the impact of micro-particles with a diameter of 18 µm, was determined using the electron moire method and numerical simulations. The in-plane plastic strain around the impacted particle was found to be as high as 9.1%, and the value sharply decreased with the increase of the distance to the edge of the impacted particle. The diameter of the plastic area was about 40 µm, which was approximately 2.2 times larger than the particle size. The experimental results were compared with numerical simulation results, and good agreement between the results was found. The electron moire technique can be a useful tool for the measurement of the deformation field induced by an impacted particle in a very local area with a size on the order of microns.

Анализ современного состояния и перспективы развития методов контроля натяжения радиоотражающего сетеполотна на развертываемый каркас крупногабаритной зеркальной антенны

The article considers the problems of developing an operating automated method for monitoring the force and uniformity of tension of a radio-reflecting mesh on the deployable frame of large mirror antennas. Based on the performed analysis of known control methods they are classified as contact mechanical methods and non-contact optical ones. It is shown that only optical monitoring methods provide automated control of the tension force of the radio-reflecting mesh on the frame. Among the known optical methods for monitoring, only the moire band method allows creating an immediate picture of the uniformity of the tension of the radio-reflecting mesh over the entire surface under consideration. The method is based on the revealed relationship of moire patterns with the uniformity and tension force of the radio-reflecting mesh. The advantages of the described method are shown; the main advantage is the possibility of installing a radio-reflecting mesh on the deployable frame of the large mirror antenna in real time. Due to its versatility, the proposed method can be used in any other structures where the element being tested is a grid, regardless of the material from which it is made.

Dynamic out-of-plane displacement measurement using the instantaneous analysis phase-shifting method

This paper presents an instantaneous analysis shadow moire method for dynamic out-of-plane displacement measurement. The shadow moire method is widely applied to the measurement of the out-of-plane displacement, such as the deformation or warpage on the surface of the objects. Generally, the method of phase shifting is used to analyze the phases of the shadow moire fringes and to obtain the out-of-plane displacement. To generate accurate phase shifting, the grating must be moved step by step precisely. However, the step motion provided by the conventional mechanical device is neither accurate nor prompt. In this study, a novel stair-structured plate consisting of a series of 4-step-height sets is designed to produce shadow moire fringes with the quadrature phase. The quadrature-phase fringes are utilized to extract instantaneously the shadow moire phase for measurement of the dynamic out-of-plane displacement of an object. Experiments show that our method can effectively detect the dynamic out-of-plane displacement with a micrometric scale resolution and is capable of suppressing the discrepancy of displacement to 0.83 $$\%$$ . The proposed measurement method of the out-plane displacement is suitable for the pressure sensing or application of the tactile sensor.

Wpływ masy szkolnego plecaka transportowanego skośnie na prawym lub lewym barku i przy różnoimiennym biodrze na cechy postawy w płaszczyźnie strzałkowej i poprzecznej 7-letnich uczniów obojga płci

Introduction. The continuing percentage of postural statics disorders may have its roots in the method of carrying the loads of school supplies. Aim. The aim of the study was to show the effects of the load of the container with school supplies carried obliquely on the left shoulder and right hip or on the right shoulder and left hip in the sagittal and transverse planes on the posture. Material and methods. Body posture tests were carried out on a group of 65 pupils aged 7 years, using the projection moire method in four positions: 1-the habitual posture, 2 – the posture after a 10-minute asymmetric loading, 3 – the posture assumed one minute after removing the load, 4 - two minutes after taking the load off. Physical fitness was measured with the Sekita test. The analysis included the values of posture features to determine the significance of their differences and correlation with physical fitness to determine its relationship with the size of these differences. Conclusions. (1) The mode of carrying school items obliquely on the right or left shoulder and on different hips may cause significant adaptation changes in the skeletal and muscular system. It should be assumed that the bigger these changes are, the longer the carriage time is, the greater the mass of the container and the intensity of physical effort are. The changes are not gender specific. The analyzed carriage method should not be practiced among 7-year-old children of both sexes. (2) The overall fitness level shows a diversified relationship with changes in the values of postural traits as a result of the assumed carriage of school supplies. This relationship is bigger among boys. In case of girls, correlations are observed between endurance and the size of the inclination angle of the thoracic-lumbar spine. Among boys, all the features of physical fitness correlate most often with asymmetry of convexity of the lower angles of shoulder blades and the pelvic torsion in the transverse plane. The impact is gender dependent.

Application of Displacement and Rotating Angle Measurement in Time Series Using Sampling Moire Method to a Plant Structure

Application of Displacement and Rotating Angle Measurement in Time Series Using Sampling Moire Method to a Plant Structure

Two-axes tilt sensing using circular gratings moiré

A circular grating moire method is proposed for sensing the tilt magnitude (θ) and tilt direction (α) for tilt about two orthogonal axes. A device consisting of a pair of fixed (upper) and semifloating (lower) circular gratings inside a water-filled acrylic container has been developed. The moire pattern images for tilt angles ranging from 0 deg to 7 deg are captured using a webcam, processed by low-pass filtering and transformed from Cartesian-to-polar coordinates. This is followed by column-wise fringe center localization using polynomial fitting, unwrapping of the extracted fringe centers, and sine-curve fitting. The peak-to-valley height (hpv) and phase shift (φ) of the unwrapped and fringe centers were determined from the fitted sine curve. The relationship between hpv and θ is found to be parabolic with the y-intercept at its minimum point, whereas that between φ and α is linear. From the tilt sensing experiments, the mean absolute errors in θ and α are found to be 0.16 deg and 3.1 deg, respectively, with uncertainty of ±0.027 deg and ±0.5 deg at 95% confidence level. The proposed device is capable of sensing tilt magnitude and direction along two orthogonal tilt planes and can potentially be applied in landslide monitoring.

Photogrammetric evaluation of body posture of 6-year-old boys training judo, in three repeated assessments.

The purpose of this work was to assess changes in body posture in a group of 6-year-old boys training judo, compared to a control group, in three repeated examinations. The study included 88 boys aged 6. Fifty-one of them started judo training in sports clubs at the beginning of the school year (JU). The control group included 37 boys attending reception classes in primary schools, selected at random (NT). Body posture was assessed 3 times at 3-month intervals, according to the general methodology of the Moire's technique, and 15 body posture indices were obtained as a result: 7 in the sagittal plane, 1 in the axial plane and 7 in the coronal plane. The system for photogrammetric body posture assessment of CQ Elektronik System was used in this study. The ANOVA test showed that neither the group factor - the fact of judo training - nor the time factor had any significant effect on the number of "deviations from normal values" of body posture (p > 0.05). Statistically significant intergroup differences were noted for six body posture indices measured with the Moire's method. Steadily decreasing numbers of "deviations from normal values" of body posture indices in the JU group were observed over the three examinations. Regular 6-month judo training had a statistically significant effect on a decrease of body rotation in the axial plane - the effect of judo training may be considered corrective in this case.

Assessment of body posture with the Moire's photogrammetric method in boys practising judo versus their non-sports-practising peers

Summary Objective Regular judo training may induce favourable developmental changes in body posture of boys. The purpose of this work was to assess changes in body posture of 8-year-old boys training judo versus a control group in two repeated assessments. Methods The study included 73 boys aged 8. Thirty-six of them started judo training in sports clubs at the beginning of the school year (JU). The control group included 37 boys attending first and second classes of primary schools, selected at random (NT). Body posture was assessed with the Moire's method, two times, at a 6-month's interval between the two assessments. Distributions of the values of the obtained variables were assessed with the W Shapiro–Wilk test. Non-parametric tests were used for their analysis. The median, mean and SD were calculated. To evaluate the differences between the T1 and T2 results, the Wilcoxon matched-pairs test was used, and to evaluate the intergroup differences both for the first and for the second measurement – the Mann–Whitney U test, adjusted for continuity. Results In group JU, the time factor (T1–T2) had a significant effect (P ≤ 0.05) on changes of 6 body posture indices. In the first assessment, there was a significant difference between the JU and NT groups with respect to 5 body posture indices; in the second assessment, there were only two differences. Conclusion Regular 6-month's judo training in the examined boys resulted in deepening of physiological spinal curvatures, progressing symmetrisation of shoulder blades and spine alignment to the C7–S1 line.

Development of Solute-solvent Separation Soft Lithography Grating for Measuring High-temperature In situ Deformation Using Scanning Electron Microscope Moiré Method

In this study, a technique is developed for fabricating high-temperature solute-solvent separation soft lithography (HSS-SL) grating for metallic materials. Using this technique, a 150 lines/mm crossing-type grating is directly fabricated on the surface of a miniaturized single edge notch tension (SENT) specimen. Further, the microstructure of the grating is analyzed using scanning electron microscope (SEM) and atom force microscope. The grating is found to be highly suited for forming high-contrast SEM moire fringes. In addition, the chemical composition of the grating is characterized using energy dispersive X-ray spectroscope (EDS), whose results indicate that the grating exhibits good resistance to high-temperature oxidation owing to the high heat endurance of its constituent materials, SiO and SiO2. With respect to high-temperature applications, the HSS-SL grating is employed successfully for measuring the linear thermal expansion coefficient of GH2036 alloy at temperatures of 25-600 °C. Moreover, the high-temperature displacement and strain fields around the semicircular notch of the SENT specimen are determined based on the SEM moire. These results confirm that thus-fabricated HSS-SL gratings show high potential for use in high-temperature in situ deformation measurements using the SEM moire method.

A Phase Compensation Method for Phase Extraction of Abrupt Surfaces in Projection Moiré

Projection moire method is a high-resolution, non-contacting and full-field optical measurement technique. But the 2π-ambiguity problem in phase unwrapping limits the phase difference between neighbouring pixels under π which makes projection moire method ineffective at measuring abrupt surfaces or steps. This paper aims at putting forward a phase compensation method to solve this 2π-ambiguity problem in projection moire. Since the phase of moire pattern is the variance between the phase of specimen grating on object’s surface and the phase of the reference grating, our method is to calculate the phases of specimen grating and the reference grating respectively, regard their difference as the phase of the moire pattern in theory and correct the wrong unwrapped moire fringe phase with integral multiple of 2π. In order to acquire the phase of specimen grating which also has the 2π-ambiguity problem, using multiple fringe pictures with different pitches. The experiments successfully reconstruct two objects with discontinuities in their surfaces. This phase compensation technique no longer requires us to count fringe orders or find a reference point to mark the zero-order moire fringe during experiments.

Form Follows Force: A theoretical framework for Structural Morphology, and Form-Finding research on shell structures

With the springing up of freeform architectures, the key problem to structural engineers is to generate structural forms with high structural efficiency subject to the architectural space constraints during the conceptual design process. In this research, a theoretical framework for Structural Morphology has been proposed, that provides an effective solution to the problem. To enrich the proposed framework, systematic Form-Finding research on shell structures is conducted.

Development of Measurement and Monitoring Method for Crack Width in the Concrete by Moiré method

It is very important to measure the deformation of the structural parts of the large constructions for the health onitoring or damage evaluation of the constructions. The Moiré methods are measurement methods of the deformation using moiré phenomena which can be observed when two grids were overlapped. In this study, a new method to measure the crack width of the concrete structural materials using Moire method has been developed. The growth of the crack width in the concrete specimens with model grid during splitting tensile test was measured by this method.

Electronic-projecting Moire method applying CBR-technology

Electronic-projecting method based on Moire effect for examining surface topology is suggested. Conditions of forming Moire fringes and their parameters’ dependence on reference parameters of object and virtual grids are analyzed. Control system structure and decision-making subsystem are elaborated. Subsystem execution includes CBR-technology, based on applying case base. The approach related to analysing and forming decision for each separate local area with consequent formation of common topology map is applied.