Installation Errors Research Articles

Method and Experiment for Quantifying Local Features of Hard Bottom Contours When Driving Intelligent Farm Machinery in Paddy Fields

The hard bottom layer of a paddy field has a great influence on the driving stability and the operation quality and efficiency of intelligent farm machinery. For paddy field machinery, continuous improvements in the accuracy and operation efficiency of unmanned precision operations are needed to realize unmanned rice farming. In the context of unmanned farm machinery operation, the complicated hard bottom layer situation makes it difficult to quantify the local characteristics of paddy fields. In this paper, an unmanned direct rice seeding machine chassis is used to maneuver the operation field and collect the hard bottom layer information simultaneously. This information is used to design a data processing method that automatically calibrates the sensor installation error and performs abnormal value rejection and 3D sample curve denoising of the contour trajectory. A hard bottom layer surface profile evaluation method based on the local sliding surface roughness is also proposed. The local characteristics of the hard bottom layer were quantified, and the results from the test plots showed that the mean value of the local roughness was 0.0065, where 68.27% of the plots were distributed in the variation range of 0.0042~0.0087 and 99.73% were distributed in the variation range of 0~0.0133. Using the test field data, the surface roughness features were verified to describe the variability in representative working conditions, such as the transport, downfield, operation, and trapping of unmanned intelligent farm machinery. When driving intelligent farm machinery, the proposed method for quantifying local features of the hard bottom layer can provide feedback on the local environmental features at any given position of the machinery. The method also provides a reference for the design optimization of unmanned systems, which can help to realize speed adaption and improve the local path tracking control accuracy of smart farming machines.

An Improved Rotational Modulation Scheme for Tri-Axis Rotational Inertial Navigation System (RINS) with Fiber Optic Gyro (FOG)

An optimized scheme can improve the navigation accuracy of RINS without changing the inertial devices. In the multi-position stop scheme, the IMU remains stationary for most of the time, which makes motor control easier. However, the installation errors and the scale factor errors of FOG can cause platform misalignment after a certain angle of rotation around the horizontal axis, resulting in a velocity error. Continuous rotation can suppress time-varying errors better, which is of particular importance for FOG, but it can also increase the sawtooth error of the navigation output, and the error in the direction of rotation cannot be offset. To integrate the advantages of both rotation schemes, we propose an improved rotational modulation scheme for tri-axis RINS. In this scheme, the inner gimbal rotates in a two-position and four-order manner, while the middle and outer gimbals rotate continuously in the order of forward-reverse-reverse-forward. Simulation and navigation test results demonstrate that this improved rotational modulation scheme can effectively improve navigation accuracy by 50% and 25% compared with continuous rotation around the azimuth axis and a 16-position scheme with the same inertial devices, which is of great importance for RINS with FOG.

Differences in participant characteristics and observed child restraint use between population-based and restraint fitting service samples

Objective To compare characteristics and restraint use between a population-based and fitting service sample of child restraint users. Method Characteristics of the two samples were compared using chi-squared tests. Differences in errors in restraint use observed in the two samples were modeled using logistic regression. Results There were significant differences in child age (p < 0.001), and restraint types (p < 0.001) between the two samples, with more younger children in the fitting service sample. Controlling for differences in restraint type, the odds that adult participants were female were 61% less in the fitting service sample than in the population-based sample (OR 0.39, 95%CI 0.21–0.71). The odds that adult participants perceived a large risk associated with restraint misuse (OR 3.62, 95%CI 1.33–9.84), had a household income in the highest bracket (OR 3.89, 95%CI 1.20–12.62) and were living in areas of highest socioeconomic advantage (OR 2.72, 95%CI 1.22–6.06) were approximately three times higher in the fitting service sample. Overall, more participants had errors in restraint use in the population-based sample (p = 0.021). However, after controlling for restraint type, securing errors were three times more likely (OR 3.34, 95%CI 1.12–10.2), and serious installation errors were almost twice as likely (OR 1.91, 95% CI 1.09–3.39) in the fitting service sample. Conclusions While less resource intensive, convenience and/or fitting service samples may be less representative than population-based samples. Given the need for efficiency, methods that combine randomized population-based invitations to participate in restraint fitting check day events across geographically representative areas may be useful for ongoing surveillance of child restraint use.

Online Calibration of RIMU Based on Multistage EKF

Redundant inertial measurement units (RIMUs) are more reliable than normal IMUs, but they are suffering from the calibration of non-orthogonal gyroscopes and accelerometers. In this paper, aiming at the problem of relying on the orthogonal axis IMU information and error term coupling in the online calibration of RIMUs, a method based on the multi-stage EKF algorism is proposed. In this method, the calibration model of the inertial system is established, which does not depend on the orthogonality with the inclined axis inertial system, meanwhile, the attitude, velocity, and position information is taken as the measurement, and a filtering model is established based on the EKF method. Based on this model, the observability of the calibration method is proved, and the window and threshold for secondary filtering are set to reduce the coupling effect of scale factor error and installation error. The digital simulation indicates that the proposed method can provide high-precision online calibration results for the inclined axis scale factor error and installation error of RIMUs, and the calibration error is below 10%.

Ease of Use ratings and real-world child restraint system errors from Safe Kids Illinois seat checks, 2015–2019

Background Child restraint systems (CRSs) significantly reduce risk of crash-related injury, however installation and use errors undermine their benefits. The National Highway Traffic Safety Administration (NHTSA) created the Ease of Use (EOU) rating system to help guide consumers and incentivize manufacturers to improve their products. The EOU rating system assigns one to five stars to four CRS features and overall. Our study assessed the relationship between EOU ratings and CRS installation and use errors documented in seat checks conducted by child passenger safety technicians (CPSTs). Methods We performed a secondary analysis of data from Safe Kids Illinois seat check records from 2015 through 2019 and EOU ratings from 2008 to 2020. Five types of errors were documented by CPSTs. Study authors (JYL and MLM) used a tiered system to match seat check model numbers to EOU ratings. We calculated chi-square statistics and performed logistic regression analyses to assess for EOU as a predictor of relevant CRS errors (e.g., tether errors for forward-facing CRSs). Results Our analyses included 2132 seat check observations, of which 217 (10.2%) were exact, 244 (10.5%) were probable, and 1671 (78.4%) were near matches via sorting and web search. Errors were most common for seat belts (70.7%) and least common for recline angle (36.9%). Star ratings for instructions, vehicle installation, and labels were associated with recline angle and seat belt errors. Star ratings for instructions, labels, and securing child were associated with harness errors. CRSs with 4-star and 5-star ratings had lower odds of errors for recline angle (Odds Ratio (OR) 0.62; 95% Confidence Interval (CI): 0.43, 0.89 and OR 0.31; 95% CI: 0.17, 0.56) lower anchors (OR 0.59; 95% CI 0.40, 0.89 and OR 0.38; 95% CI: 0.21, 0.68), and harness (OR 0.56; 95% CI: 0.40, 0.76 and OR 0.19; 95% CI: 0.10, 0.35) when compared with 1 and 2-star CRSs. Conclusions This study provides evidence in support of NHTSA’s EOU ratings as predictors of some CRS installation and use errors among caregivers who obtain seat checks. A higher star rating may be helpful for caregivers when choosing a CRS that will yield lower installation errors.

Improving the Accuracy of Multipole Magnetic Encoder by Three-Phase Hall

Magnetic encoders have widespread applications in various fields such as aerospace, automotive, robot joint control and machine tool turntables. For instance, obtaining accurate rotation angles of motors is crucial for servo motor control. Herein, we propose an angle-solving algorithm based on a dual-multipair pole magnetic encoder. First, we analyze the nonlinearity issue caused by installation error of the Hall signal and devise a self-adjustment algorithm for the analog signal. Second, we improve the high speed and robustness of the encoder in identifying eigenvalue intervals while solving for angles. Finally, through the big data analysis, the calibration compensation of curve fitting error was performed, and experiments were conducted to verify the effectiveness of the real-time angle-solving algorithm in a high-precision encoder.

Shear resistance of an anchoring coupler applied in demountable concrete connection at varying shear positions

Demountable structures are designed to reduce carbon emissions and energy consumption in the construction sector by reusing structural components. This paper focuses on an anchoring coupler with demountable property used in the demountable precast concrete structure. The shear resistance of the anchoring coupler at varying shear positions was investigated, considering the influence of installation and fabrication errors in actual projects. Firstly, several shear tests of the anchoring coupler were conducted. The ultimate capacities and failure modes of anchoring couplers with varying shear positions were obtained. The bearing capacity of the anchoring coupler without the gap between the beam and column is about 1.34 times that with 45 mm gap. The shear model of the anchoring coupler was fitted by the bilinear curves. Secondly, the numerical model of the anchoring coupler was established and verified. And the influence of the shear position on the ultimate strength was further analyzed by parametric analysis. A simplified calculation method of the shear resistance of the anchoring coupler with varying shear positions was proposed. The design equation for predicting the tension-shear interaction was recommended, considering the similarity between the anchoring coupler and conventional bolt. The aim is to provide theoretical guidance for the safety design of the anchoring coupler and optimize the beam-column connection, which is conducive to expanding the application of the demountable precast concrete structure.

Coarse and Fine Two-Stage Calibration Method for Enhancing the Accuracy of Inverse Finite Element Method.

The inverse finite element method (iFEM) is a novel method for reconstructing the full-field displacement of structures by discrete measurement strain. In practical engineering applications, the accuracy of iFEM is reduced due to the positional offset of strain sensors during installation and errors in structural installation. Therefore, a coarse and fine two-stage calibration (CFTSC) method is proposed to enhance the accuracy of the reconstruction of structures. Firstly, the coarse calibration is based on a single-objective particle swarm optimization algorithm (SOPSO) to optimize the displacement-strain transformation matrix related to the sensor position. Secondly, as selecting different training data can affect the training effect of self-constructed fuzzy networks (SCFN), this paper proposes to screen the appropriate training data based on residual analysis. Finally, the experiments of the wing-integrated antenna structure verify the efficiency of the method on the reconstruction accuracy of the structural body displacement field.

Investigation of static characteristics for linear rolling guide with considering geometric errors

A linear rolling guide (LRG) is extensively used in machine tools, while its static characteristics are not fully understood. This work developed a static stiffness characteristic model with preload and initial load, raceway center-distance errors, and rail installation errors, which is applied to an instance and verified by experiment. The key in this investigation is to equate the skirt of the slider with a cantilever beam and innovatively adopt the principle of line strain to convert the internal contact force into the expansion of the slider’s skirt to the outside deformation. Compared with only considering preload, the proposed model agrees better with the experimental results, which provides a starting point for studying dynamic properties and accuracy maintenance.

Solutions to Preventing Mistake in Building Electrical Installation and Maintenance In Urban Area Based on Skills Training

Electricity plays an important role in the functionality of a building. To ensure the required electrical competencies are met, it is essential to provide appropriate training. Therefore, this community service program based on the needs of the assisted village aimed at providing training to potential dropout youths, equipping them with skills in operating and maintaining building electrical installations, enhancing awareness regarding the importance of proper and correct electrical installations, and fostering energy-independent village. The training included several stages namely preliminary study, planning, implementation, mentoring, monitoring and evaluation. The results of the activity showed that the participants of the training obtained operational as well as building electrical system maintenance skills. These acquired competencies led to the improved standard of living, increased welfare, and the prevention of hazards resulting from errors in electrical installation and maintenance within the village of Giri Mekar. The outcome of this community service activity was that in the assisted village a number of skilled installer cadres had emerged, possessing skills in the operation and maintenance of building electrical installation systems.

Evaluation of transfer length of CFRP tendon in pretensioned concrete beam using embedded FBG sensors

This study aimed to determine the transfer length of pretensioned concrete beams strengthened with carbon fiber-reinforced polymer (CFRP) using a fiber Bragg grating (FBG) sensor. The transfer length is the distance along the tendon that is critical to ensuring effective prestressing force and structural capacity of the concrete beam. Typically, electric strain gauges are used to measure the transfer length, but they can produce measurement errors due to installation errors and data noise. In this study, an FBG sensor was embedded in a CFRP tendon instead of a strain gauge, enabling accurate measurements of tendon strain and transfer length.

An Installation Angle Error Calibration Method in an Ultra-Short Baseline System Based on a Dual Transponder

Abstract The installation error of an acoustic transceiver array is one of the important error sources in an ultra-short baseline (USBL) system. In a USBL system with a positioning accuracy of 0.5%, an installation error angle of 1° will lead to a positioning error of 1.7% times the slant distance. In this paper, a dual transponder-based installation angle error calibration method for USBL is proposed. First, the positioning errors induced by various installation angles are deduced and analysed using the linear measurement of seafloor targets. Then, an iterative algorithm is proposed that estimates the rolling alignment error, pitching alignment error, and heading alignment error, in that order. The simulation and experienced results show that, after three iterations, the estimates of the three alignment errors can converge quickly, all of the estimates converge to within 0.001° and the estimated values are very close to the true values. The horizontal positioning error caused by the installation error angle can be reduced by nearly 75%. The method has good effectiveness and robustness, and can greatly improve the positioning accuracy of the USBL system.

Modeling and Compensation of Inertial Sensor Errors in Measurement Systems

In the field of surveying and mapping, inertial sensor deterministic errors are poorly understood, and error calibration and compensation are not carried out. Thus, in this study, the effects of three types of deterministic errors (i.e., bias, scale factor error, and installation error) in a conventional inertial measurement unit (IMU) error model on a navigation system are theoretically deduced and verified by simulation. Subsequently, navigation experiments are carried out to investigate the effects of the three deterministic errors on the navigation system. The experimental results show that the gyro bias has the strongest influence on the navigation and positioning accuracy of the system. Consequently, we designed a two-position continuous calibration scheme to calibrate the IMU. The calibration scheme can simultaneously calibrate the bias error of the gyroscope and the accelerometer. When calibrating the bias error of the 0.005°/h order of magnitude, the maximum relative error is 13.16%, and the rest of the calibration relative errors are less than 10%, which verifies the effectiveness of the calibration path designed in this paper. The system is compensated by using the IMU bias calibration results, and the navigation experiment results show that the position accuracy and heading accuracy are improved by 72.68% and 79.65%, respectively, through the calibration and compensation of IMU bias error. Therefore, the position and heading accuracy of the system will be greatly improved by calibrating and compensating the bias error through the two-position calibration path before the IMU is used.

Analysis of Polarization Detector Performance Parameters on Polarization 3D Imaging Accuracy.

Three-dimensional (3D) reconstruction of objects using the polarization properties of diffuse light on the object surface has become a crucial technique. Due to the unique mapping relation between the degree of polarization of diffuse light and the zenith angle of the surface normal vector, polarization 3D reconstruction based on diffuse reflection theoretically has high accuracy. However, in practice, the accuracy of polarization 3D reconstruction is limited by the performance parameters of the polarization detector. Improper selection of performance parameters can result in large errors in the normal vector. In this paper, the mathematical models that relate the polarization 3D reconstruction errors to the detector performance parameters including polarizer extinction ratio, polarizer installation error, full well capacity and analog-to-digital (A2D) bit depth are established. At the same time, polarization detector parameters suitable for polarization 3D reconstruction are provided by the simulation. The performance parameters we recommend include an extinction ratio ≥ 200, an installation error ∈ [-1°, 1°], a full-well capacity ≥ 100 Ke-, and an A2D bit depth ≥ 12 bits. The models provided in this paper are of great significance for improving the accuracy of polarization 3D reconstruction.

Performance of asphalt shingles under simulated hurricane winds and evaluation of current installation practices

This paper investigates the wind resistance of asphalt shingles, evaluates the efficiency of their current installation methods, and addresses the lack of a system-level resistance metric from a wind engineering standpoint. The study examined the wind performance of asphalt shingles considering three installation practices recommended in high-velocity wind areas and three nailing non-conformities due to workmanship issues by conducting full-scale failure assessment tests at the NHERI Wall of Wind Experimental Facility. Roofing Application Standard (RAS) No. 115 and FEMA's recommended practices, with and without modifications, were used as recommended practices; while missing nails, over-driven nailing, and high-nailing cases were simulated as installation deviations or errors. Monoslope, gable, and hip roof decks were also used to study the contribution of roofing geometries. The results showed that asphalt shingles installed using methods recommended by the current guidelines may be vulnerable to wind flows from critical directions. Asphalt shingles, tested in the current work, experienced failure at wind speeds below their design level, especially due to cavity pressurization. Nailing non-conformities were also observed to compromise shingles' performance. Additionally, asphalt shingle failure modes, extents, and areas varied with roof geometries and the employed installation methods.

All-Parameter System-Level Calibration for SINS/CNS Based on Global Observability Analysis

Before using the strap-down inertial navigation system (SINS)/ celestial navigation system (CNS) integrated navigation system, the calibration of its error parameters is a necessary process to improve the system accuracy. In this paper, an all-parameter system-level calibration method has been proposed, which utilizes Kalman filtering for simultaneously estimating the bias, scale factor, misalignments of inertial measurement unit (IMU), and installation errors of the star sensor. The observation has been constructed using the inertial navigation output information and the starlight vector measured by the star sensor. The observability of the error parameters has been analyzed theoretically, and the optimal excitation conditions for each error parameter are obtained. The effects of the angle between the starlight vector and the optical axis of the star sensor, and the attitude of the IMU, on the estimation accuracy of the installation error of the star sensor are also given. Finally, a 10-order rotation scheme has been designed and all the error parameters can be optimally excited. The simulation and experimental results demonstrate that all the error parameters have better stability and repeatability, when compared with the traditional method, and the initial alignment error of 3.4" is better than 13.1" of the traditional method. Moreover, the installation error of the star sensor can be estimated with a high precision only when the angle between the starlight vector and the optical axis of the star sensor exceeds 1°. It is shown that the proposed method can effectively improve the navigation performance of the SINS/CNS integrated navigation system.

Impact of installation error and tracking error on the thermal-mechanical properties of parabolic trough receivers

As the solar energy utilization technology for renewable clean energy, actual parabolic trough receivers are subject to tracking errors and absorber tube installation errors, and the bellows and Kovar ring under these errors have a significant impact on the receiver's safety. Based on the MCRT-FVM-FEM principles in this paper, a receiver's optical-thermal-stress mathematical model is modeled and the thermal-stress performance and safety of the receiver's key components under two errors are evaluated. The correlation between the bellows and Kovar ring's performance and the two errors is analyzed. The results demonstrate that the lower tracking errors and larger installation errors markedly increment the absorber's deformation and have a negative impact on the receiver safety. Bellows and Kovar ring's asymmetrical temperature distribution causes variable swell and uneven stress under tracking and installation errors. Temperature gradient variation of bellows is more sensitive under errors than Kovar rings. Kovar ring's compressive stress rises substantially as the Y-directional installation error varied from −15 mm to 15 mm compared to other errors. With tracking errors exceeding 8 mrad, bellows' tensile stress and Kovar ring's compressive stress diminish under installation error. Thus, larger tracking errors significantly reduce the threat to the receiver when installation errors exist.

Experimental studies on structural performance of precast concrete shear walls with innovative UHPC-based connections

Ultrahigh-Performance Concrete (UHPC) is an advanced class of cement-based composite that offers excellent bond performance with steel bars. When compared to conventional approaches, using UHPC-based connections for Precast Concrete Shear Walls (PCSWs) has the advantages of smaller bar lap-spliced lengths and greater tolerance to installation errors. In this study, a two-stage scheme was proposed. Firstly, the bond properties between lapped steel bars and UHPC were determined to provide guidelines for designing PCSWs. A total of 15 pullout samples were designed and tested under direct tension. Failure patterns including steel bar pullout, cover splitting, and steel bar rupture were summarized. The basic splice length of steel bars with diameters limited to 14 mm in UHPC should be at least 6 times the bar diameter. In the second stage, the seismic performance of PCSWs with UHPC-based connections was investigated. Two full-scale PCSWs and two monolithic walls were constructed and tested cyclically in axial compression ratios of 0.1 and 0.3. In PCSWs, the splice length of additional bars (the one-row) in UHPC was set as 10 times the diameter to allow for a safe margin. PCSWs with UHPC-based connections demonstrated higher load-carrying capacity, better ability to dissipate energy, and comparable ductility to monolithic counterparts. An evaluation of test results also met the acceptance criteria for shear wall systems that could be considered as structures assigned to high seismic performance.

Mathematical model of phased array antenna aperture in the presence of errors in the position of antenna elements

The analysis of the directional characteristics of a phased array antenna is one of the main problems in the development of an antenna. The key issue in carrying out this analysis is an adequate representation of the directional characteristics of the phased array antenna with known directional patterns and the set-up as part of the aperture of antenna elements. There are many works considering the directional characteristics of the antenna, taking into account the mutual connection between the antenna elements. A number of works are devoted to the study of the directional characteristics of a phased array antenna in the presence of random errors of the amplitude-phase distribution in the radiating aperture. However, the issues related to the influence of the antenna elements installation error in the radiating aperture on the directional characteristics of the phased array antenna practically did not receive their consideration. With this in mind, this article discusses a mathematical model of the radiating aperture of a phased array antenna in the presence of errors in the antenna elements installation. At the same time, the installation error means not only the displacement of the antenna elements, but also its rotation relative to three axes, due to a violation of the shape of the radiating aperture. The objective of the article is to investigate the influence of the antenna element installation errors, including the displacement and reversal of the antenna elements in the radiating aperture, on the directional characteristics of the phased array antenna, based on strict consideration of the relationship between the directional characteristics of the phased array antenna and the parameters of the antenna elements installation in the radiating aperture. The main results obtained in the article are as follows. 1. A mathematical model of the radiating aperture of the phased array antenna, taking into account the errors of installation of the antenna elements in the aperture, including displacement of the phase center of the antenna elements and rotation of the antenna elements relative to the plane of the radiating aperture at three angles. 2. Investigation of the main patterns of changes in the directional characteristics of the phased array antenna due to the presence of errors in the antenna elements installation in the radiating aperture of the phased array antenna. In particular, errors in the installation of antenna elements practically do not lead to a change in the main beam either in width or in level. The most significant changes in the directional characteristics are manifested as follows: the structure and level of the side lobes of the directional patterns of the phased array antenna change; there is a cross-polarized component in the directional pattern, which, unlike the main component, is weakly directional. The developed mathematical model and the obtained simulation results allow us to determine the relationship between the parameters of the antenna elements installation errors as part of the phased array antenna aperture with a change in the amplitude, phase and polarization directional pattern, on the basis of which requirements for the accuracy of the parameters of the radiating aperture and the accuracy of the antenna elements installation can be formulated. These results are most significant for communication and radar systems that use orthogonal polarization signals when receiving and radiating.

Case Study: Modeling a Grain Bin for Safe Entry Retrofit

All new grain bins produced after 2018 are recommended to have anchor points capable of handling a 2000 lb loading for attachment of bin entry lifeline systems. This study aims to assess the feasibility of a safe entry anchor point retrofit by using finite element analysis (FEA). We used a grain bin owned by Penn State for 3D FEA modeling in SolidWorks. To validate the model results from the FEA model, first strain and then deflection measurements were conducted on the grain. Strain gauges were applied to the grain bin in five locations and strain values were obtained after applying static loads. The strain gauge measurements from the experimental study were compared to the strain output from the FEA simulation. The error seen was far greater than was expected. The most pertinent error source was strain gauge installation error and equipment failure. Then, the vertical roof deflection of the bin was measured using a precision phase-comparison laser while applying incremental static loads to the retrofitted rescue anchor points. The FEA model results were compared to the experimentally measured deflection results. A 3D FEA model of a grain bin was created. A high amount of error was observed in deflections between the measured and FEA modeling. The errors have resulted from the assumptions made during the model creation. However, the SolidWorks Simulation model still may be used to estimate loading scenarios in a safe and non-destructive way. Based on the research findings, the project team recommends that the suitability of any bin to safely accommodate a lifeline and anchor point system must be verified on a case-by-case basis. Evaluation by a professional structural engineer and consulting with the manufacturer are recommended. This recommendation extends to all-grain bins, including those post-2018.