Initial Attitude Research Articles

A Robust In-Motion Optimization-Based Alignment for SINS/GPS Integration

Initial alignment is of vital importance to the inertial navigation system, and the in-motion initial alignment is a critical stage for the moving vehicles. In this paper, an in-motion alignment method for SINS/GPS integration is investigated. Using the velocity, which is obtained from GPS, the observation and the reference vectors are constructed. Different from previous methods, a robust attitude determination method is devised to finish the in-motion alignment process when there are outliers contained in the GPS outputs. To implement the robust attitude determination method, the error of the magnitudes of the observation and reference vectors is calculated, and this error is used to detect the outliers. However, the bias of the inertial sensors, the expectation and variance of the calculated error of the magnitude is time-varying, so that the detected accuracy of the outliers degrades. To address this defect, the new normalized error of the magnitude is constructed by a robust parameter identification method, then the expectation and variance of the new normalized error are constant. Using the new normalized error, the initial attitude is obtained by the robust optimization-based alignment (ROBA) method. The simulation and field tests are designed to validate the performance of the proposed method, the alignment results show that the proposed method can detect the outliers accurately, and it gets the similar alignment accuracy with the current popular method when there are no outliers in the auxiliary velocity of GPS.

Consumer intention to purchase GM soybean oil in China: effects of information consistency and source credibility

ABSTRACT Consumers’ potential reactions toward genetically modified (GM) foods affect their commercial feasibility and determine the decisions of economic agents. Inconsistent information on GM foods has created a sense of uncertainty in Chinese consumers’ mind. This paper studies how the information about risks and benefits of GM foods from major sources influences Chinese consumer intention to purchase GM soybean oil. This analysis uses data from a survey of 880 residents randomly sampled from 13 cities in Jiangsu province. Using a multinomial logit model, we analyze the effects of information consistency and source credibility. The results show because of new information about 17.36% of consumers increase their intention to purchase GM soybean oil, and 15.10% of consumers decrease purchase intention. Compared to consistent information, inconsistent information can maximize change of purchase intention. The attitude change is greatest when there is a moderate difference between the new information and the initial consumer attitude. Furthermore, trust in biotechnology research institutes, government departments about GM, and GM experts are easier to promote consumers to change their intention to purchase GM soybean oil in a positive direction. Finally, we discuss implications for agencies as to strengthening the regulation and supervision of information sources, and including public-involved policies. Abbreviations: GM, Genetically modified; GMOs, Genetically modified organisms; AGGMO, Center of Agriculture’s Genetically Modified Organisms’ safety management and policy research organization at Nanjing Agricultural University; MARA, Ministry of Agriculture and Rural Affairs; ¥1 (RMB)≈$6.8 (USD).

A Unified SO(3) Approach to the Attitude Control Design for Quadrotors

This paper proposes a two-phased problem reformulation approach to solve the quadrotor UAV attitude control problem. Given an initial attitude, the objective is to design a control to drive it toward a desired value. The first phase begins with the definition of three types of errors pertaining to attitude discrepancy, followed by the utilization of virtual control with which the dynamics of quadrotor’s attitude and angular velocity are then unified under the framework of SO(3), rendering the original control problem much more transparent to tackle. Through cancellation of certain unwanted terms emerging from the unification process, entry-wise treatment of the remaining matrix dynamics is then employed in the second phase to transform it further into the stabilization problem of a 3-dimensional linear time-invariant system that is fairly easy to solve since to which standard feedback designs such as linear quadratic regulator and pole placement are readily applicable. In addition to the classical designs, a specialized and structurally simple controller is provided to reduce the number of gains. To account for system parametric uncertainties, external disturbances, and sensor measurement errors and noises, a second controller based on classical $H_{\infty }$ theory is presented to enhance the robustness of the design. A numerical example is given, and computer simulations are conducted to generate error and control trajectories to assess and compare the effectiveness of the presented designs.

Sensorless attitude estimation of three-degree-of-freedom actuator for image stabilization

Space recognition is a crucial issue for autonomous systems such as unmanned aerial vehicles, walking robots, and autonomous cars. These systems are necessary to obtain information using a camera while moving. However, reduction in recognition accuracy and system size increase has created problems. To solve these problems, we proposed the three-degree-of-freedom (DOF) actuator for image stabilization. This paper proposes a novel initial position estimation method and sensorless attitude estimation method for the three-DOF actuator to further downsize and reduce weight. The effectiveness of the proposed methods is verified by a magnetic field analysis, using a three-dimensional finite element method and numerical simulations.

Fear of coronavirus and forbid/allow asymmetry as determinants of acceptance of COVID-19 pandemic related restrictions and persistence of attitudes towards these regulations

In this study (N = 110) factors influencing formation of attitudes toward COVID-19 related restrictions as well as factors influencing stability or change of these attitudes were tested. Specifically, the study concentrated on two possible determinants of formation and changing attitudes toward COVID-19 related restrictions – fear of coronavirus and presenting restriction in forbid vs. allow frames. A restriction presented in the forbid frame was rejected more strongly than a restriction presented in the allow frame. For changing attitudes, a mere thought paradigm was used. This activity was not able to change these negative attitudes toward a forbid framed restriction. A higher level of fear of coronavirus was related to a more positive (or rather – less negative) attitude toward an allow framed restriction and allows this attitude to be changed to be more supportive of restrictions than initially. Moreover, the effect of fear was partially mediated by the changes in the confidence of initial attitude inconsistent thoughts.

MLCA-A Machine Learning Framework for INS Coarse Alignment.

Inertial navigation systems provides the platform’s position, velocity, and attitude during its operation. As a dead-reckoning system, it requires initial conditions to calculate the navigation solution. While initial position and velocity vectors are provided by external means, the initial attitude can be determined using the system’s inertial sensors in a process known as coarse alignment. When considering low-cost inertial sensors, only the initial roll and pitch angles can be determined using the accelerometers measurements. The accuracy, as well as time required for the for the coarse alignment process are critical for the navigation solution accuracy, particularly for pure-inertial scenarios, because of the navigation solution drift. In this paper, a machine learning framework for the stationary coarse alignment stage is proposed. To that end, classical machine learning approaches are used in a two-stage approach to regress the roll and pitch angles. Alignment results obtained both in simulations and field experiments, using a smartphone, shows the benefits of using the proposed approach instead of the commonly used analytical coarse alignment procedure.

Improving the calibration process of inertial measurement unit for marine applications

Marine navigation systems have very accurate sensors, such as 0.01deg/hr gyro drift stability and 0.1mg/year accelerometer bias stability. Common calibration methods and equipment do not meet the accuracy required. In this paper, a systematic method for calibration of an inertial measurement unit (IMU) for marine applications is proposed which is not based on the accuracy of the calibration turn table and only requires one specific plate to determine the initial attitude of the IMU and functions independently of the turn table. The first contribution of this paper is to derive a model for systematic calibration of IMU that expresses the rotation matrix error and velocity as a linear function of the calibration parameters at any time. As the second contribution, this paper proposes a calibration algorithm with only using an initial, specific plate. Using the actual data, it was found that the proposed algorithm provides a good estimation of the parameters.

In-Motion Initial Alignment Using State-Dependent Extended Kalman Filter for Strapdown Inertial Navigation System

The in-motion alignment of the strapdown inertial navigation system (SINS) is still a challenging problem due to the complex environmental changes that occur during carrier movement. This article proposes a novel initial alignment method by integrating the advantages of the Special Orthogonal Group of order 3 [SO(3)] representation and the optimal attitude estimation alignment idea. In this method, the SO(3) is used to represent the initial attitude matrix, and the optimal attitude estimation alignment model is established by analyzing the influence of the sensor error during the calculation process. Next, state-dependent extended Kalman filter is investigated by mapping the SO(3) equations to the Lie algebra space, and the Lagrange formula is used to separate the state-dependent errors in the Lie algebraic filtering equation. The simulation and experimental results indicate that the proposed initial alignment method can achieve better alignment accuracy and shorter alignment time than existing methods and can fulfill the in-motion alignment tasks for SINSs in various environments.

Coupled Orbit-Attitude Dynamics of Tethered-SPS

In this paper, a dynamic model for long-term on-orbit operation of the tethered solar power satellite (Tethered-SPS) is established. Because the Tethered-SPS is a super-large and super-flexible structure, the coupling among the orbit, attitude, and structure vibration of the system should be considered in comparison with the traditional spacecraft dynamic models. Based on the absolute nodal coordinate formulation (ANCF), the dynamic equation of the Tethered-SPS is established by Hamiltonian variational principle, and the dual equations of the Hamiltonian system are established by introducing generalized momentum through Legendre transformation. The symplectic Runge–Kutta method is used for numerical simulation, and the validation of the modeling method is verified by a numerical example. The effects of orbital altitude, initial attitude angle, length of solar panel, and orbital eccentricity on the orbit and attitude of the Tethered-SPS are analyzed. The numerical simulation results show that the effect of orbital altitude and length of solar panel on the orbital error of midpoint of beam is small. However, the initial attitude angle has a significant effect on the orbital error of midpoint of solar panel. The effect of the length of solar panel on the attitude angle of the system is not significant, but orbital altitude, orbital eccentricity, and initial attitude angle of the system severely affect the attitude angle of the system. Then, the stability of the system is affected.

M-M Estimation-Based Robust Cubature Kalman Filter for INS/GPS Integrated Navigation System

In the engineering applications, Kalman filter (KF) is the most commonly used for INS/GPS integration. This KF-based integration is prone to divergence because of two typical problems. One is that the predicted state and measurement are contaminated by non-Gaussian noise. The other is that the initial attitude error is too large. Until now, there arise many algorithms dealing with only one of these two problems, but the algorithms which can deal with both two problems are few. Motived by this situation, an M-M estimation-based cubature Kalman filter (MMCKF) is proposed which innovatively combines the M-M estimation and nonlinear cubature Kalman filter (CKF) to enhance the performance of INS/GPS integration system in the case that above two problems occur at the same time. Simulation and vehicle-mounted experiment results validate its accuracy and robustness.

The Simulation of Aircraft Ditching Based on ALE Method

Ditching is an emergency measure for landing on the water when the aircraft cannot continue to fly in an accident. In order to verify the performance of the aircraft ditching, this paper carry out a simulation study on ditching of fixed-wing aircraft on the water. First determine the simulation method, material model and constitutive equation, and then analyze the influence of the sinking speed and attitude changes on the ditching of the aircraft. The simulation method adopts arbitrary Lagrange-Euler method (ALE). The results show that as the sinking speed increases, the load will increase accordingly. As the initial attitude angle increases, the vertical acceleration gradually decreases, and the longitudinal acceleration is basically the same, the pressure acting area gradually moves backward, and the pressure area gradually decreases. It is necessary to take appropriate local strengthening measures on the dangerous region.

S-commerce: Influence of Facebook likes on purchases and recommendations on a linked e-commerce site

Social networking site (SNS) driven e-commerce, the latest social commerce (s-commerce) phenomenon, gains prominence with the introduction of the call-to-action feature. The call-to-action feature on any sponsored post or advertisement on SNS redirects the user to a linked e-commerce website that offers the product. Information cues available on the SNS are expected to influence user decision making on the linked e-commerce site. Set in the context of Facebook driven e-commerce, this study explores how likes on Facebook influence user's purchase and recommendation decisions on a linked e-commerce website. Using controlled experiments we find that a higher volume of likes on Facebook leads to a higher likelihood of purchasing and recommending a product on the linked e-commerce site. This effect is found to be mediated by the user's initial product attitude formed on Facebook. An additional analysis examining the strength of the influence reveals that the mere presence of likes is not sufficient to impact the user's decision making. In fact, a low volume of likes elicits user behavior similar to absence of likes. The influence is effective only if the number of likes is substantially high. The findings of the study add to the s-commerce literature by establishing the inter-site influence of Facebook likes on user's purchase and post-purchase decisions and providing empirical evidence of the efficacy of SNS-driven e-commerce.

Diagnosis and long-term monitoring of adenomas of the ciliary body epithelium by ultrasound biomicroscopy.

The natural course of adenomas of the ciliary-body epithelium (ACE) is uncertain, due to their low incidence and their frequent initial surgical management.Their differential diagnosis with amelanotic melanoma or metastasis is challenging and diagnostic biopsies require sufficient tissue and highly specialized pathologists. Ultrasound biomicroscopy offers high resolution images and clear sonographic signs suggestive of ACE allowing a more precise differential diagnosis and therefore, a more conservative initial attitude. Descriptive, retrospective, non-comparative study of consecutive cases of ACE observed between October 2003 and December 2019 in a reference unit in ocular oncology of a tertiary hospital. Patients were studied on a quarterly basis the first year and, subsequently, every 6 months with a complete ophthalmological exam and ultrasound biomicroscopy with the platform Aviso linear scanning 50 MHz probe (Quantel Medical, Clermont-Ferrand, France). Three ACE were analysed for a median of 3 years (interquartile range: 2.5-5.5 years). Clinical features include a whitish-to-brown spherical mass, with engorged superficial vessels. Ultrasound biomicroscopy shows an oval-spherical shape, medium-to-high echogenicity, low acoustic attenuation, regular internal structure, and respect for the neighboring structures. By their clinical-ultrasonographic characteristics, one was considered an adenoma of the pigmented ciliary-body epithelium (browner and hyperechogenic) and two were classified as adenomas of the non-pigmented ciliary epithelium (whitish appearance and medium-echogenicity). Ultrasound biomicroscopy allows a reasonable clinicalsonographic suspicion of ACE. An initial conservative management is proposed as a safer option for stable, mildly symptomatic patients, avoiding aggressive sight threatening treatments.

Optimization-based Attitude Determination in Geodetic Applications

AbstractA new approach to determining the attitude of a rigid body is suggested, which does not rely on the use of magnetometers. In the framework of this approach, the problem of determining the attitude reduces to solving a minimization problem for a function of three variables (angles characterizing the initial attitude of the body). The proposed method can be employed in precise geodetic measurements carried out with the use of a geodetic pole with a satellite antenna and an IMU installed on its top when, for some reasons, the surveyor cannot position the pole vertically (e.g., near walls or buildings). The use of the traditional approach, which relies on a compass and accelerometers, in this case does not ensure the desired accuracy of the attitude determination due to magnetic disturbances (both external ones and those induced by the receiver) affecting badly compass readings. The discussion is illustrated by results of field experiments.

INS/GPS 통합 항법 시스템의 정지/비행 중 정렬 수행 시 자세 및 가속도계 바이어스의 가관측도에 대한 이론적 분석

This paper presents a theoretical analysis on the degree of observability of attitude and accelerometer bias under static and in-flight alignment by solving the error covariance matrix explicitly. By following the Kalman filter covariance update process, the elements of this matrix can be resolved under simple assumptions, and provide a good conformity to the simulation results. The solution consists of the magnitude of gravity, the given acceleration, and the initial covariance. By using this formula, the covariance of the estimation error, which represents the degree of observability, can be examined accurately before the estimation process. For the initial attitude covariance, set by the coarse alignment, it is shown that the error covariance of the roll, pitch, and accelerometer bias in the x and y axes decrease by half of their respective initial values under static alignment. Moreover, the estimation error variance of the yaw is shown to decrease significantly under in-flight alignment.

PENINGKATAN KETERAMPILAN GERAK DASAR ROLL BELAKANG PADA ANAK SEKOLAH DASAR

The purpose of this study was to determine the improvement of basic skills back roll using aids in class III students of SD N 1 Beringin Raya Bandar Lampung city in 2019. The method used in this research is the Classroom Action Research method with two cycles , where in each cycle using different actions. The first cycle with the use of part-time learning, and the second cycle with the use of teacher assistance.The subjects in this study were students III of SDN 1 Beringin Raya, Bandar Lampung City, totaling 17 students. Data collection was taken from tests in the form of observations of the basic roll rear motion skills which include initial attitude, implementation and final attitude. The results of this study indicate an increase in basic roll rear motion skills through the use of assistive devices in each cycle, while the increase in each cycle is as follows the first cycle of 52.94%, and the second cycle 82.35%Keywords: Enhancement, Skills, Basic Movement, Gymnastics, Back Roll

Global Distributed Attitude Tracking Control of Multiple Rigid Bodies via Quaternion-Based Hybrid Feedback

This article investigates the leader-following attitude tracking control problem of multiple rigid body systems in the presence of uncertain parameters and disturbances. The communication constraint is considered that only a subset of followers have access to the leader, and a quaternion-based nonlinear hybrid distributed observer is first proposed to estimate the leader's trajectory for each follower. In particular, the proposed distributed attitude observer always evolves on the 3-D unit sphere $\mathbb {S}^{3}$ . This property guarantees the feasibility of the observer-based distributed control scheme, since the separation principle is satisfied. By incorporating a hysteresis-based switch of a binary logic variable for each pair of neighboring rigid bodies, the proposed hybrid distributed observer achieves the global asymptotic stability for any initial attitude and avoids the unwinding phenomenon. Next, an observer-based attitude tracking control law is developed by combining adaptive technique and hybrid theory, which does not require precise model information and has good robustness to the disturbances. In addition, it is shown that the attitude tracking errors converge to the origin globally asymptotically. Finally, simulation results are provided to validate the theoretical results.

Perceived Responsiveness Increases Tolerance of Attitude Ambivalence and Enhances Intentions to Behave in an Open-Minded Manner.

Can perceived responsiveness, the belief that meaningful others attend to and react supportively to core defining feature of the self, shape the structure of attitudes? We predicted that perceived responsiveness fosters open-mindedness, which, in turn, allows people to be simultaneously aware of opposing evaluations of an attitude object. We also hypothesized that this process will result in behavior intentions to consider multiple perspectives about the topic. Furthermore, we predicted that perceived responsiveness will enable people to tolerate accessible opposing evaluations without feeling discomfort. We found consistent support for our hypotheses in four laboratory experiments (Studies 1-3, 5) and a diary study (Study 4). Moreover, we found that perceived responsiveness reduces the perception that one's initial attitude is correct and valid. These findings indicate that attitude structure and behavior intentions can be changed by an interpersonal variable, unrelated to the attitude itself.

Nonlinear Spacecraft Attitude Control via Cascade-Forward Neural Networks

The problem of spacecraft attitude control has been addressed in the literature via several linear and nonlinear algorithms. In the current study, cascade-forward neural networks have been used to mimic the behaviour of the High Performance Nonlinear Discrete Controller (HPNDC). Controller stability is proven via Lyapunov second method. The developed control algorithm has the ability to work during all of the spacecraft operational modes and alleviates many problems associated with other nonlinear algorithms existing in the literature. Performance of the algorithm has been tested against various nonlinear attitude control algorithms including HPNDC, Sliding Mode (SM) Controller, Nonlinear Dynamic Inversion (NDI)controller, and Adaptive Neuro-Fuzzy Inference Systems (ANFIS) controller. The proposed neural networks control algorithm achieved a good performance compared to the aforementioned control algorithms. The behaviour of the HPNDC control algorithm has been used for training of the Neural Networks due to its numerous advantages when operating in linear and nonlinear operational modes. To prevent data overfitting, 10% of the training data set are used for testing. The training ratio is selected to be 90%. Gravity gradient torques acting on EGYPTSAT-1 spacecraft are considered the main acting disturbance. The developed control algorithm can nullify the initial high angular velocities and attitude angles of the spacecraft within two orbits.

Variable-time-domain neighboring optimal guidance and attitude control of low-thrust lunar orbit transfers

Lunar orbit dynamics and transfers at low altitudes are subject to considerable perturbations related to the gravitational harmonics associated with the irregular lunar mass distribution. This research proposes the combination of two techniques applied to low-thrust lunar orbit transfers, i.e. (i) the variable-time-domain neighboring optimal guidance (VTD-NOG), and (ii) a proportional-derivative attitude control algorithm based on rotation matrices (PD-RM). VTD-NOG belongs to the class of feedback implicit guidance approaches, aimed at maintaining the spacecraft sufficiently close to the reference trajectory. This is an optimal path that satisfies the second-order sufficient conditions for optimality. A fundamental original feature of VTD-NOG is the use of a normalized time scale, with the favorable consequence that the gain matrices remain finite for the entire time of flight. VTD-NOG identifies the trajectory corrections by assuming the thrust direction as the control input. Because the thrust direction is fixed with respect to the spacecraft, VTD-NOG generates the desired orientation pursued by the attitude control system. A proportional-derivative approach using rotation matrices (PD-RM) is employed in order to drive the actual spacecraft orientation toward the desired one. Reaction wheels are considered as the actuators that perform attitude control. Extensive Monte Carlo simulations are performed, in the presence of nonnominal flight conditions related to (i) lunar gravitational harmonics, (ii) gravitational pull of the Earth and the Sun as third bodies, (iii) unpredictable propulsive fluctuations, and (iv) errors on initial attitude. The numerical results unequivocally demonstrate that the joint use of VTD-NOG and PD-RM control represents an accurate and effective methodology for guidance and control of low-thrust lunar orbit transfers.