Rapid Alignment Research Articles

Design of a fast transfer alignment matching algorithm

In order to estimate the misalignment angle of align system effectively, this paper constructs a traditional 14 state rapid transfer alignment model, considers the problem that traditional velocity error definition is not completely accord with the consistency of coordinate system, the improved differential equation of velocity error is applied to transfer alignment, constructs an improved 12 state rapid transfer alignment model. Finally, the performance of the two alignment algorithms is tested by vehicle-mounted experimental data under the conditions of no maneuver, C shape maneuver and S shape maneuver, and the experimental result of the two algorithms is compared and analyzed. The experimental result shows that the improved 12 state rapid transfer alignment algorithm not only has better alignment accuracy than the traditional 14 state rapid transfer alignment algorithm, but also reduces the model complexity, reduces the system calculation, and avoids the influence of flexural deflection and dynamic misalignment angle. The yaw angle alignment accuracy is improved by 45%, 65% and 53% under the conditions of no maneuver, C shape maneuver and S shape maneuver, respectively.

Rapid and accurate initial alignment of the low-cost MEMS IMU chip dedicated for tilted RTK receiver

The new global navigation satellite system real-time kinematic (RTK) receivers with tilt compensation extend the applicability of high-precision RTK positioning to previously restrictive environments since the pole is no longer required to be maintained vertically. The rapid and accurate initial alignment of the built-in low-cost inertial measurement unit (IMU) is a critical technical issue and currently remains a challenge for the tilted RTK. We address this problem by proposing a method specific to the determination of the IMU initial heading for the tilted RTK. In this approach, the IMU heading is calculated from the angle between the inertial navigation system (INS)- and RTK-indicated position increment vectors in the horizontal plane based on the fact that the INS- and RTK-indicated trajectories in the short term are similar in shape. Instead of conventional INS mechanization, the INS-indicated trajectory is determined using the gyro-derived attitude and pole length by treating the pole movement as the motion of a rigid body with a fixed point to enhance the trajectory accuracy. The experiment results indicate that the initial heading is accurately determined to 1.15° at a 98.2% confidence level within only 2–3 s when using a dollar-level IMU chip without any additional sensors, e.g., a magnetometer. The proposed algorithm satisfactorily meets the requirements of the tilted RTK application, and its accuracy and convergence speed are higher than those of the current methods reported in publications and product sheets.

High-resolution real-time 360∘ 3D surface defect inspection with fringe projection profilometry

Since a slight variance in production processes can make the entire production run defective, defect inspections are indispensable procedures in manufacturing processes to ensure high quality of each item before entering the next manufacturing step. Three-dimensional (3D) optical shape measurement technologies are widely applied for surface defect inspection of complex workpieces because of its high-accuracy and digitization. However, the complex surface structure and position of the test object can pose serious challenges, making inspections still relatively slow, expensive, and complicated in implementation and maintenance. In this work, we propose a real-time 360∘ 3D surface defect inspection approach based on fringe projection profilometry without any auxiliary equipment for position control. Firstly, a multi-view 3D measurement based on geometric constraints is employed to acquire high-accuracy depth information from different perspectives. Then, a cycle-positioning-based registration scheme with the establishment of the pose-information-matched 3D standard digital model is proposed to realize rapid alignment of the measured point cloud and the standard model. Finally, a minimum 3D distance search is driven by a dual-thread processing mechanism for simultaneous scanning and detecting to quantify and locate 3D surface defects in real time. Experimental results show that our method can accurately identify the surface defects of complicated objects in real time in an extremely simple (hand-held) manner, saving a lot of operational expenses on precision alignment and position-orientation adjustment. The proposed method holds tremendous potential for quality control in many facets of industry, such as product development, testing, and manufacturing.

Wheeled Vehicle Skidding at $$\boldsymbol{\mu}$$-Split

The dynamics of a biaxial four-wheeled vehicle is simulated when drive wheels of one of its axes get into the $$\mu$$ -split surface. The $$\mu$$ -split surface is a section of the reference plane with different friction coefficients for the left and right wheels of one of the vehicle axes. Depending on the conditions of vehicle motion, the interaction of its wheels with the reference plane is described by the slip model or the Coulomb dry friction model. Using the methods of fractional analysis and the theory of singular perturbations, we estimate the angular velocity impulse, which is received by the vehicle body after the completion of the rapid transient alignment of the contact forces on the wheels of the drive axis.

Neural networks for faster optical alignment

A technique for providing neural network-coached alignment of optical systems is described in detail. The goal is to increase the speed of convergence to an aligned optical system. The neural network model is trained with the wavefront errors (WFEs) of thousands of randomly misaligned instances of the lens system that are modeled in Zemax OpticStudio®. The optical specialist measures the WFE of the misaligned system, then a neural network suggests specific adjustments to be made to the alignment fixturing (which adjuster, which direction, and by what amount). The technique has been developed into a MATLAB®-based tool called rapid optical system alignment with neural network assist that is shown to analytically and experimentally increase the speed of alignment. It is capable of achieving WFEs that are within a few percent of the nominally aligned condition. The ultimate goal is to deploy such a tool to enable an optical specialist to more quickly align challenging optical systems employing freeform or segmented surfaces. Analytical and experimental results for spherically symmetric systems are shown along with an outline of future work.

A Rapid and Adaptive Alignment under Mooring Condition Using Adaptive EKF and CNN-Based Learning.

Alignment of the inertial navigation system (INS) in the mooring environment should take into account the movements of the waves or wind. The alignment of the INS is performed through an extended Kalman filter (EKF) using zero velocity as a measurement. However, in the mooring condition, this is not perfect stationary, thus the measurement error covariance matrix should be adjusted. In addition, if the measurement error covariance matrix is fixed to one value, the alignment time may take longer or the performance may be reduced depending on the change in mooring conditions. To solve this problem, we propose an alignment method using adaptive Kalman filter and convolution neural network (CNN)-based learning. The proposed method was verified for the superiority of alignment time and accuracy through Monte Carlo simulation in a mooring environment.

An Autonomous Initial Alignment and Observability Analysis for SINS With Bio-Inspired Polarized Skylight Sensors

A novel autonomous initial alignment for the stationary strapdown inertial navigation system (SINS) with the bio-inspired polarized skylight sensors (PSS) is proposed to improve the precision and convergence speed in this paper. A pair of perpendicularly polarized skylight sensors with six-channels are used to measure and calculate the polarization azimuth angles, which is finally constructed a new polarized measurement error equation. With the SINS error equations, the SINS/PSS integrated navigation error equations are developed to achieve autonomous and fast initial alignment. Two types of observability, geometric observability and stochastic observability, are introduced to evaluate the integrated navigation systems. The geometric observability, which is defined by calculating the rank of the observability matrix, is analysed. It is found that the integrated navigation systems are not completely observable. Further, the degree of observability based on singular value decomposition is also used to examine the observable degree of the SINS/PSS integrated navigation system. The stochastic observability is associated with observability analysis with the estimated precision of the designed filter. The Kalman filter is designed to estimate the unknown state based on the measurements from the inertial measurement unit and PSS. Simulations and experiments demonstrate that the SINS/PSS achieve a rapid initial alignment with higher precision. Compared with the SINS, the vertical misalignment angle accuracy of SINS/PSS is improved by more than 90%, and the time cost is shortened by 60% in the simulation test. For the initial alignment experiment, the vertical misalignment greatly improved the accuracy and shorten the time cost.

Chirally Reversed Graphene Oxide Liquid Crystals.

Colloidal liquid crystals (LCs) formed by nanoparticles hold great promise for creating new structures and topologies. However, achieving highly ordered hierarchical architectures and stable topological configurations is extremely challenging, mainly due to the liquid‐like fluidity of colloidal LCs in nature. Herein, an innovative synchronous nanofluidic rectification (SNR) technique for generating ultralong graphene oxide (GO) liquid crystal (GOLC) fibers with hierarchical core‐skin architectures is presented, in which the GO sheet assemblies and hydrogel skin formation are synchronous. The SNR technique conceptually follows two design principles: horizontal polymer‐flow promotes the rapid planar alignment of GO sheets and drives the chiral‐reversing of cholesteric GOLCs, and in situ formed hydrogel skin affords some protection against environmental impact to maintain stable topological configurations. Importantly, the dried fibers retain the smooth surface and ordered internal structures, achieving high mechanical strength and flexibility. The linear and circular polarization potential of GOLC fibers are demonstrated for optical sensing and recognition. This work may open an avenue toward the scalable manufacture of uniform and robust, yet highly anisotropic, fiber‐shaped functional materials with complex internal architectures.

Socio-Economic Differences in the Development of Six-Year-Old Children in Rural Areas of East Poland

The aim of this study is to evaluate socio-economic differences in physical, cognitive, and motor development among six-year-old children living in rural areas. The study encompassed 228 children, including 118 girls and 110 boys living in different rural settlements in the Świętokrzyskie Province in Poland, who were selected through a combination of nonprobability and random sampling. The study was carried out from April to June 2014. A questionnaire was used to collect information from the parents of the children concerning the parents’ education, number of children in the family, and the number of persons per room. Based on the concept of socio-economic status (SES), three levels of quality of life conditions of each family, i.e., high, average, and low, were distinguished. The study noted considerable differences in BMI, and especially the cognitive development of the children with respect to the socio-economic status of their family. It was observed that children from rural areas who live in bad socio-economic conditions are exposed to a wide range of negative factors affecting their health, which leads to lower educational results and negative long-term biological and psychosocial consequences. The chance for more rapid alignment of development deficits for those children would have been their earlier cover of school duty.

A Novel Polar Rapid Transfer Alignment for Shipborne SINS Under Arbitrary Misalignments

The traditional polar rapid transfer alignment (RTA) are generally modeled under small angle misalignment assumption. Those linearized and nonlinear polar RTA error models presented, so far, are not capable of accurately representing the nonlinear properties of the system where the all-orientation large attitude errors happen between the master and slave strap-down inertial navigation systems (SINS). It cannot satisfy the accuracy for the SINS initialization and has a singularity in computation. In this article, the misalignment quaternion in the grid frame was selected as the state and observation. An innovative polar RTA algorithm using the quaternion matching and the augmented unscented Kalman filter (UKF) was then proposed to estimate all-orientation large attitude misalignments in polar regions. Furthermore, the associated error propagation equations were redesigned in the grid frame and with compensations for the lever-arm effect. The augmented UKF model was further adjusted to apply. Simulation and semi-physical experiment results demonstrated that the performance of the innovative polar RTA algorithm proposed here outperformed those via traditional polar RTA techniques, especially with 3-axis large-angle misalignments, and was even robust with the disturbance of lever-arm effect aggravated by the harsh polar environment.

Co-simulation of transfer alignment and CAN busbased on CANoe-MATLAB

The research on rapid transfer alignment for INS on moving base is very important in the field of the inertia technology. In order to build the real-time CAN bus network simulation system with the velocity matching model of the transfer alignmentalgorithm, CANoe(CAN open environment)-MATLAB interface is applied. The CANoe-MATLAB interface is connected with MATLAB/Simulink which has powerful modeling functions and CANoe which has perfect function of bus simulation. Modeling the transfer alignmentalgorithm by MATLAB/Simulink and providing the real-time CAN bus network communications in HIL(hardware-in-loop) simulation by CANoe. The simulations tests show that co-simulation system built by the CANoe and the MATLAB/Simulink performs favorably with rapid convergence and validity.

Adaptive UT-H∞ Filter for SINS’ Transfer Alignment Under Uncertain Disturbances

Accurate and rapid transfer alignment with large attitude errors under uncertain disturbances is crucial for the strapdown inertial navigation system (SINS). This paper proposes an adaptive UT-Hoc filter which combines UKF technology and a Hoc filter to increase the robustness of the nonlinear transfer alignment system. By focusing on the time-varying and the uncertain external disturbances, the robustness factor of the adaptive UT-H∞ filter can be adaptively adjusted to balance the robustness and filtering accuracy of the dynamic system. Then, the nonlinear error propagation model of the transfer alignment is established in detail, and the velocity plus attitude matrix measurement model is used to improve the performance of transfer alignment. Moreover, the sensor error compensation model is established to calibrate and compensate for the sensor errors of the gyros and accelerometers online during transfer alignment. The vehicle transfer alignment experiments show that the proposed adaptive UT-Hoc filter can significantly improve the transfer alignment accuracy and the pure inertial navigation accuracy compared with the existing filtering methods under uncertain disturbances.

Building Adaptable Teams for Co-configuration

In innovative organisations we are seeing an increase in cross-functional teams being built around projects. The diverse perspectives of collaborators draw from personal world-views and organisational roles, which contributes to radical collaboration across traditional boundaries of work.
 This hands-on workshop aims at testing a rapid team alignment activity in which teams propose core values and align these to the innovation learning cycle, synthesising them into foundational work practices for each phase. These are then reframed as the teams' innovation narrative.

The First Day in the Life of a Magnetar: Evolution of the Inclination Angle, Magnetic Dipole Moment, and Braking Index of Millisecond Magnetars during Gamma-Ray Burst Afterglows

Abstract The afterglow emission of some gamma-ray bursts (GRBs) shows a shallow decay (plateau) phase implying continuous injection of energy. The source of this energy is very commonly attributed to the spin-down power of a nascent millisecond magnetar. The magnetic dipole radiation torque is considered to be the mechanism causing the spin-down of the neutron star. This torque has a component working for the alignment of the angle between rotation and the magnetic axis, i.e., the inclination angle, which has been neglected in modeling GRB afterglow light curves. Here, we demonstrate the evolution of the inclination angle and magnetic dipole moment of nascent magnetars associated with GRBs. We constrain the initial inclination angle, magnetic dipole moment, and rotation period of seven magnetars by modeling the seven long-GRB afterglow light curves. We find that, in its first day, the inclination angle of a magnetar decreases rapidly. The rapid alignment of the magnetic and rotation axis may address the lack of persistent radio emission from mature magnetars. We also find that in three cases the magnetic dipole moments of magnetars decrease exponentially to a value a few times smaller than the initial value. The braking index of nascent magnetars, as a result of the alignment and magnetic dipole moment decline, is variable during the afterglow phase and always greater than three.

Multi-directional cellular alignment in 3D guided by electrohydrodynamically-printed microlattices

Recapitulating aligned cellular architectures of native tissues in vitro is important to engineer artificial tissue analogs with desired biological functions. Here a novel strategy is presented to direct three-dimensional (3D) cellular alignment by embedding cell/collagen hydrogel into the predefined electrohydrodynamically-printed microlattices. The cell/collagen hydrogel, originally filled within the printed microlattices uniformly, was found to gradually develop into densely-populated and highly-aligned bands along the longitudinal direction of the printed microlattices. The cellular alignment was highly dependent on the height, spacing and orientation of the microlattices. The presented method was applicable to multiple cell types including primary cardiomyocytes and the gaps formed between the aligned bands and the lateral walls of the microlattice facilitated the subsequent seeding and rapid alignment of other cell types which enables to engineer anisotropic multicellular tissue constructs. The engineered cardiac patches expressed mature cardiomyocyte-specific phenotypes and exhibited synchronous contractive activities. Multilayer cellular alignment with varied orientation in 3D collagen hydrogel was successfully achieved by using electrohydrodynamically-printed microlattices with layer-specific orientations. This exploration offers a promising way to engineer complex 3D tissue constructs with predefined cellular alignments. Statement of significanceFabrication of biomimetic highly-aligned complex cellular architectures has a great significance to recapitulate the unique mechanical and physiological functions of the engineered tissues (e.g., heart tissue, neuron, muscle). Here, we introduced a novel strategy to direct 3D cellular alignment by embedding cell/collagen hydrogel into the predefined electrohydrodynamically-printed microlattices without any external stimuli. The microscopical study of the dynamic alignment process of cells and collagen fibers contributed to exploring the mechanism of autonomous formation of highly-aligned cellular bands. Multilayer cellular alignment with varied orientation in 3D collagen hydrogel was successfully achieved by using the microlattices with layer-specific orientations, which showed a promising way to engineer complex 3D tissue constructs with predefined cellular alignments.

Applying space syntax for surface rapid transit planning

This paper presents a technique aimed to assist in planning of surface rapid transit alignment in a metropolitan area by applying space syntax configurational approach. The technique proposed in this study was applied to the proposed surface rapid transit network for the Metropolitan Area of Tel Aviv. For this research a bi-modal model of the spatial structure, which includes the street network as well as the planned rapid transit routes, was analyzed. The results show that that a substantial share of the network’s alignment can be described solely by measuring through-movement potentials. This finding demonstrates the significant role of spatial accessibility analysis in transit planning. Consequently, this study provides a reproducible methodology for identifying the routes which hold the highest potential to serve as strategic movement corridors at a metropolitan scale, thus improving current RTS (Rapid Transit System) planning practice.

Rapid alignment for SINS based on expansion of observation vectors in polar regions

In polar regions, the rapid convergence of meridians and the small horizontal component of Earth's rotation make traditional North-pointed initial Alignment algorithm (NA) ineffective. While Alignment algorithm based on Pseudo-Earth frame (PA) can solve the problems caused by the rapid convergence of meridians, the observability of Strap-down Inertial Navigation System (SINS) on stationary base is so poor that it takes much time to complete initial alignment. According to this case, in this paper, a novel alignment algorithm based on expansion of observation vectors is proposed to implement rapid initial alignment in polar regions. This paper mainly completes the following works: firstly, a rapid Alignment algorithm based on Expansion of Observation vectors for Pseudo-earth frame (EOPA) is proposed, then the reason for its rapid convergence is explicated by analysis of the error equations; secondly, two observability analysis methods: Singular Value Decomposition (SVD) and the Attitude Dilution Of Precision (ADOP) are adopted to compare the observability of PA with that of EOPA. Finally, semi-physical simulation shows that in polar regions, even in the case of latitude of 89° and initial misalignment angle of 3°, the azimuth misalignment error can be reduced within 0.25° in 40s. It has significant engineering application value.

Rapid Transfer Alignment of SINS with Measurement Packet Dropping based on a Novel Suboptimal Estimator

Transfer alignment (TA) is an important step for strapdown inertial navigation system (SINS) starting from a moving base, which utilises the information proposed from the higher accurate and well performed master inertial navigation system. But the information is often delayed or even lost in real application, which will seriously affect the accuracy of TA. This paper models the stochastic measurement packet dropping as an independent identically distributed (IID) Bernoulli random process, and introduces it into the measurement equation of rapid TA, and the influence of measurement packet dropping is analysed. Then, it presents a suboptimal estimator for the estimation of the misalignment in TA considering the random arrival of the measurement packet. Simulation has been done for the performance comparison about the suboptimal estimator, standard Kalman filter and minimum mean squared estimator. The results show that the suboptimal estimator has better performance, which can achieve the best TA accuracy.

RAFTS3G: an efficient and versatile clustering software to analyses in large protein datasets

BackgroundClustering methods are essential to partitioning biological samples being useful to minimize the information complexity in large datasets. Tools in this context usually generates data with greed algorithms that solves some Data Mining difficulties which can degrade biological relevant information during the clustering process. The lack of standardization of metrics and consistent bases also raises questions about the clustering efficiency of some methods. Benchmarks are needed to explore the full potential of clustering methods - in which alignment-free methods stand out - and the good choice of dataset makes it essentials.ResultsHere we present a new approach to Data Mining in large protein sequences datasets, the Rapid Alignment Free Tool for Sequences Similarity Search to Groups (RAFTS3G), a method to clustering aiming of losing less biological information in the processes of generation groups. The strategy developed in our algorithm is optimized to be more astringent which reflects increase in accuracy and sensitivity in the generation of clusters in a wide range of similarity. RAFTS3G is the better choice compared to three main methods when the user wants more reliable result even ignoring the ideal threshold to clustering.ConclusionIn general, RAFTS3G is able to group up to millions of biological sequences into large datasets, which is a remarkable option of efficiency in clustering. RAFTS3G compared to other “standard-gold” methods in the clustering of large biological data maintains the balance between the reduction of biological information redundancy and the creation of consistent groups. We bring the binary search concept applied to grouped sequences which shows maintaining sensitivity/accuracy relation and up to minimize the time of data generated with RAFTS3G process.

The Effectiveness of Acceleration Matching According to the Sensor Performance in Shipboard Rapid Transfer Alignment

In this study, the effect of acceleration matching according to sensor specifications in rapid transfer alignment is analysed. In general, the velocity and attitude information of the Master Inertial Navigation System (MINS) is used for transfer alignment. MINS angular velocity information is used to improve the alignment speed in shipboard transfer alignment. Acceleration matching, on the other hand, is generally considered an impractical option for transfer alignment. However, in the case of shipboard transfer alignment, acceleration matching is thought to be effective. In order to analyse the performance of acceleration matching, a performance index is defined and the efficiency of acceleration matching is analysed according to various sensor specifications and simulation environments. Based on the analysis of the estimated performance according to the simulation results, it is confirmed that acceleration matching in rapid transfer alignment is valid.