Target Rotation Research Articles

Cross-Modal Cues Improve the Detection of Synchronized Targets during Human Foraging

Abstract In two experiments, we explored whether cross-modal cues can be used to improve foraging for multiple targets in a novel human foraging paradigm. Foraging arrays consisted of a 6 × 6 grid containing outline circles with a small dot on the circumference. Each dot rotated from a random starting location in steps of 30°, either clockwise or counterclockwise, around the circumference. Targets were defined by a synchronized rate of rotation, which varied from trial-to-trial, and there were two distractor sets, one that rotated faster and one that rotated slower than the target rate. In Experiment 1, we compared baseline performance to a condition in which a nonspatial auditory cue was used to indicate the rate of target rotation. While overall foraging speed remained slow in both conditions, suggesting serial scanning of the display, the auditory cue reduced target detection times by a factor of two. In Experiment 2, we replicated the auditory cue advantage, and also showed that a vibrotactile pulse, delivered to the wrist, could be almost as effective. Interestingly, a visual-cue to rotation rate, in which the frame of the display changed polarity in step with target rotation, did not lead to the same foraging advantage. Our results clearly demonstrate that cross-modal cues to synchrony can be used to improve multitarget foraging, provided that synchrony itself is a defining feature of target identity.

Adaptive backstepping and sliding mode control of a quadrotor

This article proposes a simple robust adaptive control architecture with minimum parameter estimation laws for trajectory tracking of a quadrotor subjected to parametric variations and environmental disturbances. This simple control architecture aims to achieve highly accurate, robust, and fast trajectory tracking of the quadrotor in a short time with low computational cost. Firstly, the quadrotor model is divided into altitude, attitude, and position subsystems for which appropriate control methods are designed without prior knowledge of the upper bound of external disturbances. A simple adaptive fractional-order sliding mode control (AFSMC) is designed to enhance the tracking of the altitude subsystem and estimate the upper bound of the disturbances. Then, a simple adaptive backstepping control (ABC) is developed for the horizontal position to generate the required roll and pitch orientations. The adaptation laws not only estimate the upper bound of the disturbances but also adjust the controller gains thereby enhancing the robustness of the ABC. A nonsingular fast terminal sliding mode control (NFTSMC) is incorporated with a finite-time disturbance observer (FDO) to accurately suppress the disturbances, and follow the target rotation angles within a short finite-time. Simulation results showed that the compounded control structure ensures accurate, fast, and robust tracking. The AFSMC can achieve the desired altitude with a settling time of 0.31 s and root mean square error (RMSE) of 0.0454 m. The ABC can attain the target horizontal position coordinates with a settling time of (0.47 s, 0.47 s) and RMSE of (0.0370 m, 0.0518 s). The NFTSMC-FDO can achieve the desired attitude angles with a settling time of (0.11 s, 0.13 s, 0.52 s) and RMSE of (0.0098 rad, 0.0092 rad, 0.0935 rad). Performance comparisons with existing control methods in terms of settling time and RMSE demonstrated that the proposed control architecture is superior.

Rotational Motion Compensation for ISAR Imaging Based on Minimizing the Residual Norm

In inverse synthetic aperture radar (ISAR) systems, image quality often suffers from the non-uniform rotation of non-cooperative targets. Rotational motion compensation (RMC) is necessary to perform refocused ISAR imaging via estimated rotational motion parameters. However, estimation errors tend to accumulate with the estimated processes, deteriorating the image quality. A novel RMC algorithm is proposed in this study to mitigate the impact of cumulative errors. The proposed method uses an iterative approach based on a novel criterion, i.e., the minimum residual norm of the signal phases, to estimate different rotational parameters independently to avoid the issue caused by cumulative errors. First, a refined inverse function combined with interpolation is proposed to perform the RMC procedure. Then, the rotation parameters are estimated using an iterative procedure designed to minimize the residual norm of the compensated signal phases. Finally, with the estimated parameters, RMC is performed on signals in all range bins, and focused images are obtained using the Fourier transform. Furthermore, this study utilizes simulated and real data to validate and evaluate the performance of the proposed algorithm. The experimental results demonstrate that the proposed algorithm shows dominance in the aspects of estimation accuracy, entropy values, and focusing characteristics.

Parameter Extraction of Accelerated Moving Targets under Non-Quasi-Axial Incidence Conditions Based on Vortex Electromagnetic Wave Radar

Vortex electromagnetic wave radar carrying orbital angular momentum can compensate for the deficiency of planar electromagnetic wave radar in detecting motion parameters perpendicular to the direction of electromagnetic wave propagation, thus providing more information for target recognition, which has become a hot research field in recent years. However, existing research makes it difficult to obtain the acceleration and rotation centers of targets under non-quasi-axial incidence conditions of vortex electromagnetic waves. Based on this, this article proposes a variable speed motion target parameter extraction method that combines single element and total element echoes. This method can achieve three-dimensional information extraction of radar targets based on a uniform circular array (UCA). Firstly, we establish a non-quasi-axis detection echo model for variable-speed moving targets and extract echoes from different array elements. Then, a single element echo is used to extract the target’s range slow time profile and obtain the target’s rotation center z coordinate. We further utilize the target linear, angular Doppler frequency shift extremum, and median information to extract parameters such as target acceleration, tilt angle, rotation radius, and rotation center x and y coordinates. We analyzed the impact of different signal-to-noise ratios and motion states on parameter extraction. The simulation results have verified the effectiveness of the proposed algorithm.

Ultra-high order mode-assisted optical differentiator for edge detection with high tunability

An optical spatial differentiator based on the photonic spin Hall effect (PSHE) with high tunability is presented. By utilizing the characteristics of ultra-high order modes in the symmetrical metal cladding waveguide, the Fresnel reflection coefficient spectrum exhibits a narrow peak width and low trough at the resonant incident angles, resulting in high sensitivity to changes in the incident angle-induced spatial shift caused by the PSHE (the highest ∂(|r s /r p |)/∂θ value can reach 107). After polarization transformation and extinction, the output field demonstrates differential operation with respect to the input field. When applied to edge detection, our differentiator can achieve tunable resolution edge images by adjusting the incident angle. Our proposed edge detection scheme has potential applications for cellular and molecular imaging through two-dimensional extension via the target rotation.

라이프스타일에 반영된 가치체계 평가도구(Yonsei Lifestyle Profile-Values)의 구성 타당성: 이중요인(Bifactor) 모델 접근

Objective: The construct validity and reliability of the Yonsei Lifestyle Profile-Values (YLP-V) were verified to measure the value system reflected in lifestyle behaviors. Methods: Data were collected from 300 community-dwelling older adults aged 55 years and older who were registered with an online research organization. The YLP-V was used to collect data, which underwent descriptive statistics, differential item functioning, and factor analysis. Exploratory factor analysis was conducted to estimate the factor structure, and confirmatory factor analysis was used to compare and confirm the validity of four competing models (single-factor, hierarchical factor, multidimensional factor, and bifactor). Results: Exploratory factor analysis using target rotation revealed that the dimensions of the YLP-V (activity, five items; interest, four items; opinion, nine items) showed factor loadings of 0.4 or higher, indicating good construct validity. Confirmatory factor analysis indicated that the bifactor model (χ2 = 164.58**, degree of freedom = 117, root mean square error of approximation = 0.05, standard root mean residual = 0.04, comparative fit index = 0.95, Turker Lewis index = 0.93) demonstrated the best fit among the tested models. Conclusion: We identified a factor structure consistent with evidence for developing the YLP-V, which allows for a micro-level lifestyle approach. The bifactor structure, with 18 items representing activity, interest, and opinion, demonstrated validity, and the YLP-V could be valuable for measuring and understanding the value systems reflected in behaviors within a healthy lifestyle.

Demonstration of Two Multi‐Component Target Ablation Approaches and Their Application in Combinatorial Pulsed Laser Deposition

AbstractCombinatorial pulsed laser deposition (C‐PLD) based on segmented targets has led to new possibilities in the pace of discovery of novel advanced materials with significantly reduced deposition time and material consumption. However, fabrication of established segmented targets may be complex or not even possible for certain material combinations. In this article, two alternative C‐PLD techniques based on easy‐to‐fabricate segmented targets are presented. One approach uses two semi‐circular segments A and B with a systematic adjustable lateral shift of the target rotation axis from the target center. The other approach is based on a new target design defined by an ABA‐segmentation where B is a horizontal bar between two semi‐circular segments of A. Both approaches enable growth of discrete composition libraries. The concepts and important parameters are introduced and computer simulations as function of the geometric parameters are made to yield the expected thin film compositions. As proof‐of‐concept, the techniques are employed on the transparent, semiconducting ternary alloy zinc‐tin‐oxide. The simulations are in very good agreement with the experimental data. Physical properties of films grown by the demonstrated approaches are compared with those obtained by established PLD processes.

Evaluation and continuous improvement of magnetic components material design skills in interdisciplinary switched-mode power supply

The design of switched-mode power supplies (SMPSs) is a material-electrical engineering interdisciplinary problem. The design of magnetic component materials can significantly affect SMPSs’ performances. In engineering education, the design and development of solutions is an important skill for engineering students. However, the traditional engineering experiments curriculum is shown as validation and single-disciplinary experiments as well as one-sided assessment results. To foster open-ended exploration, enhance students’ material design skills, and improve skills adaptation, students must tackle real engineering problems and develop practical design solutions. This paper proposes an exploratory factor analysis and knowledge graph-based method for evaluating and continuously improving magnetic components material design skills in the context of SMPS design tasks. First, we used the multiple imputation method to address the missing data. Each imputed data was analyzed to extract factors through parallel analysis, ordinary least squares estimation, and target rotation. Then, we identified four sub-skills: efficiency design skill, passive device design skill, power magnetic reduction design skill, and power economy design skill. The RMSEA for the four-factor model is 0.042, suggesting a good fit to the data. We established the relationships between these sub-skills and SMPS performance metrics. Furthermore, the average of the factor scores from each of the imputed datasets and the SMPS design constraints were combined to obtain the cut-off scores to evaluate engineering students’ achievements in these sub-skills. Finally, we constructed an SMPS magnetic components material knowledge graph, which could recommend specific experimental tasks, relevant knowledge areas, and SMPS performance metrics, providing personalized guidance to designers.

Wi-Rotate: An Instantaneous Angular Speed Measurement System Using WiFi Signals

We propose the design, implementation, and evaluation of an instantaneous angular speed (IAS) measurement system, namely Wi-Rotate, using commercial-off-the-shelf (COTS) WiFi hardware. Wi-Rotate exploits the Channel State Information (CSI) of WiFi signals to extract the physical characteristics of the rotation object to achieve accurate contact-free IAS measurements. Wi-Rotate contains three main components: Wi-Fresnel model, Wi-Phase model, and a combination model. Wi-Fresnel model explores the signal amplitude variation features when the rotating object cuts the Fresnel zone boundary to track target rotation. Wi-Phase model leverages signal phase variation and formalizes the problem of determining IAS as a linear programming problem. The combination model combines the IAS values obtained by Wi-Fresnel and Wi-Phase and utilizes a clustering method to further improve measurement accuracy. Comprehensive experiments are conducted to demonstrate the advantages of Wi-Rotate in terms of accuracy, sensing range, and system latency. Wi-Rotate is able to achieve real-time rotation measurements at an accuracy higher than 99% when the target is within 2 meters. Even when the target is 3 meters away, Wi-Rotate can still achieve an accuracy of 94%, demonstrating the long-range tracking capability which is critical for industrial applications.

LiDAR Point Clouds Semantic Segmentation in Autonomous Driving Based on Asymmetrical Convolution

LiDAR has become a vital sensor for autonomous driving scene understanding. To meet the accuracy and speed of LiDAR point clouds semantic segmentation, an efficient model ACPNet is proposed in this paper. In the feature extraction stage, the backbone is constructed with asymmetric convolutions, so the skeleton of the square convolution kernel is enhanced, which leads to greater robustness to target rotation. Moreover, a contextual feature enhancement module is designed to extract richer contextual features. During training, global scaling and global translation are performed to enrich the diversity of datasets. Compared with the baseline network PolarNet, the mIoU of ACPNet on the SemanticKITTI, SemanticPOSS and nuScenes datasets are improved by 5.1%, 1.6% and 2.9%, respectively. Meanwhile, the speed of ACPNet is 14 FPS, which basically meets the real-time requirements in autonomous driving scenarios. The experimental results show that ACPNet significantly improves the performance of LiDAR point cloud semantic segmentation.

Robust oblique Target-rotation for small samples

IntroductionOblique Target-rotation in the context of exploratory factor analysis is a relevant method for the investigation of the oblique simple structure. It was argued that minimizing single cross-loadings by means of target rotation may lead to large effects of sampling error on the target rotated factor solutions.MethodIn order to minimize effects of sampling error on results of Target-rotation we propose to compute the mean cross-loadings for each block of salient loadings of the independent clusters model and to perform Target-rotation for the block-wise mean cross-loadings. The resulting transformation-matrix is than applied to the complete unrotated loading matrix in order to produce mean Target-rotated factors.ResultsA simulation study based on correlated independent clusters model and zero-mean cross-loading models revealed that mean oblique Target-rotation resulted in smaller bias of factor inter-correlations than conventional Target-rotation based on single loadings, especially when sample size was small and when the number of factors was large. An empirical example revealed that the similarity of Target-rotated factors computed for small subsamples with Target-rotated factors of the total sample was more pronounced for mean Target-rotation than for conventional Target-rotation.DiscussionMean Target-rotation can be recommended in the context of oblique factor models based on simple structure, especially for small samples. An R-script and an SPSS-script for this form of Target-rotation are provided in the Supplementary Material.

Stiffening of I-section MRF beams against degradation due to local buckling

Moment resisting frame (MRF) beams under cyclic loading are vulnerable to local flange and web buckling. The Seismic Provisions for Structural Steel Buildings (AISC341) prescribe width-to-thickness ratio limits, which are contingent on target rotations during predefined cyclic loadings. Some rolled I-sections available in the market cannot be employed in special MRFs since they fall short of satisfying the AISC341 flange slenderness limit. Moreover, local buckling leads to a decrease in both strength and stiffness in cyclically loaded MRF beams, ultimately increasing the risk of frame side-sway collapse. This paper introduces a stiffening method aimed at improving the behavior of I-section MRF beams. The proposed method involves placing a pair of stiffeners at the plastic hinge regions. A two-phase numerical study was conducted to assess the effectiveness of this approach. In the first phase, nine unstiffened beam cross-sections with varying flange and web slenderness were considered. The slenderness limits specified by AISC341 were evaluated based on cyclic analyses of these beams. In the second phase, a parametric study was conducted on the same cross-sections, with the flange width and the placement of the pair of stiffeners considered as variables. The results revealed a substantial improvement in behavior with the addition of a pair of stiffeners. Cross-sections that failed to meet the flange slenderness limit could be used in MRFs when stiffened. The optimal location for the stiffeners was found to be significantly influenced by the flange width. Design recommendations for the ideal stiffener placement are presented in this paper.

Chlorhexidine-Containing Electrospun Polymeric Nanofibers for Dental Applications: An In Vitro Study.

Chlorhexidine is the most commonly used anti-infective drug in dentistry. To treat infected void areas, a drug-loaded material that swells to fill the void and releases the drug slowly is needed. This study investigated the encapsulation and release of chlorhexidine from cellulose acetate nanofibers for use as an antibacterial treatment for dental bacterial infections by oral bacteria Streptococcus mutans and Enterococcus faecalis. This study used a commercial electrospinning machine to finely control the manufacture of thin, flexible, chlorhexidine-loaded cellulose acetate nanofiber mats with very-small-diameter fibers (measured using SEM). Water absorption was measured gravimetrically, drug release was analyzed by absorbance at 254 nm, and antibiotic effects were measured by halo analysis in agar. Slow electrospinning at lower voltage (14 kV), short target distance (14 cm), slow traverse and rotation, and syringe injection speeds with controlled humidity and temperature allowed for the manufacture of strong, thin films with evenly cross-meshed, uniform low-diameter nanofibers (640 nm) that were flexible and absorbed over 600% in water. Chlorhexidine was encapsulated efficiently and released in a controlled manner. All formulations killed both bacteria and may be used to fill infected voids by swelling for intimate contact with surfaces and hold the drug in the swollen matrix for effective bacterial killing in dental settings.

High Precision Motion Compensation THz-ISAR Imaging Algorithm Based on KT and ME-MN

In recent years, terahertz (THz) radar has been widely researched for its high-resolution imaging. However, the traditional inverse synthetic aperture radar (ISAR) imaging algorithms in the microwave band perform unsatisfactorily in the THz band. Firstly, due to THz radar’s large bandwidth and short wavelength, the rotation of the target will result in serious space-varying(SV) range migration and space-varying phase error. Furthermore, it is challenging to accurately estimate the rotational velocity and compensate for phase errors in the presence of severe range migration effects. Therefore, in this paper, a high-precision THz-ISAR imaging algorithm is proposed. The algorithm includes the following step: First, the SV first-order range migration(FRM) is corrected using keystone transform (KT); then, the minimum entropy based on modified newton (ME-MN) is used to estimate the rotational velocity roughly, and the remaining SV second-order range migration(SRM) is corrected to obtain the range profile with the envelope alignment. Finally, the echo after the envelope alignment is processed for the second time based on ME-MN. The target rotation velocity is accurately estimated, and the phase error is compensated to obtain a well-focused imaging result. The validity of the proposed method is verified by numerical simulation and electromagnetic calculation data.

Seismic Performance Evaluation of Moment Resistance Connection by Load Velocity.

AbstractThe seismic performance of beam‐column connections is typically evaluated using a loading protocol specified by codes such as AISC. This protocol involves applying incremental and repeated loads at a specified speed to reach a target rotation angle, with a low load velocity of about 0.5 mm/s to 1.0 mm/s. However, testing at such a low load velocities may not fully account for brittleness breakdown due to factors such as a reduction in material toughness and a decrease in maximum deformation rate caused by stress concentration in vulnerable areas at high load velocities.Therefore, it is important to verify the seismic performance of connections, including their plastic deformation ability, under the influence of dynamic loads with high velocities, such as those experienced during an earthquake. We conducted a static and dynamic experiment on welded connections and extended end plate connections to analyze the effect of load velocity on connections behavior.Our results showed that increasing the load velocity reduced the strength of the connection, its plastic deformation capacity, and energy absorption capacity. These findings confirm that load velocity can significantly affect the seismic performance of connections and suggest that the current loading protocol may not fully capture the connection behavior under dynamic loads.

The Leipzig Leadership Model: Measuring leadership orientations

AbstractThe Leipzig Leadership Model (LLM) connects theory and practice. Building on actor-world relations and insights from motivational psychology (actor-action relations), the LLM proposes a holistic framework able to integrate the existing plethora of leadership theories and styles. This opens up a new perspective on a comprehensive understanding of leadership roles. With its four leadership orientation dimensions of purpose, entrepreneurial spirit, responsibility, and effectiveness, the LLM enables leaders to identify and reflect on relevant leadership competencies. In order to facilitate future research on the LLM and its dimensions, we report on two studies that are developing and validating a 32-item LLM-based scale. We applied oblique bifactor target rotation in a bifactor Exploratory Structural Equation Model within CFA approach in a German sample (N = 309) with robust WLSMV-estimates to fit an LLM-based model to the data. The results suggest a good fit. Furthermore, as ECV, PUC and ARPB support the multidimensional nature of the scale, we report the appropriate bifactor statistical indices. After parallel back translation, an English version of the scale was tested in a second sample (N = 311) to replicate our earlier findings. This study facilitates future empirical research by providing a concise and integrative self-rating measure of leadership orientations. We further strengthen the scientific foundation of the LLM by empirically testing its conceptually developed four-factor structure. The scale provides a starting point for further research into leadership orientations (also as standalone subscales), and offers an applicable guideline for self-reflection and decision-making.

Tactical Features of Operation of the Specialized Anti-Epidemic Team of the Rospotrebnadzor on the Territory of the Republic of Crimea under Conditions Characteristic of a Combined Emergency

The tactics of activities of the specialized anti-epidemic team (SAET) of the Rospotrebnadzor on the territory of the Republic of Crimea has been determined by the conditions of emergency situation of sanitary-epidemiological and natural character. The aim of the work was to analyze the features and effectiveness of the functional response of the Rospotrebnadzor SAET to the dynamics of epidemiological risks caused by emergency of combined nature in the Republic of Crimea in 2020–2021. Materials and methods. We used report materials of the Rospotrebnadzor SAET; information materials of the Interregional Rospotrebnadzor Administration in the Republic of Crimea and the Federal city of Sevastopol; “Coronavirus Monitor” service data. Results and discussion. Tactical decisions on the work of the SAET on the territory of the Republic of Crimea had the stage-by-stage nature. In the event of a complication of the epidemiological situation on the new coronavirus infection, a mobile group of the SAET was involved. Together with specialists from the Plague Control Station of the Republic of Crimea, it conducted 211 148 studies of clinical material to detect SARS-CoV-2 RNA using PCR during the period of 2020–2021. In response to the emergence of additional risks caused by the consequences of a dangerous meteorological phenomenon, the group of SAET specialists was reinforced and mobile complex (MС) of the SAET was deployed. During the entire course of work, a prolonged target rotation of personnel was implemented in order to provide for adequate laboratory support for monitoring upon epidemiological indications in accordance with the nature of emerging risks. That tactics of operation made it possible to conduct 18 591 screening studies of clinical material for acute respiratory viral infections (ARVI), natural-focal and acute intestinal infections (AII), as well as the study of 280 water samples for cholera. Introduction of the sequence of operational procedures adapted for work in emergency situations resulted in isolation of 10 Vibrio cholerae O1 ctxA–</sup tcpA–/em> strains from water bodies. The phased involvement of the mobile group of SAET specialists, and later the MC of the SAET, in combination with the consistent operational target rotation of personnel in order to provide adequate laboratory support for monitoring studies, determined the tactical features of the SAET functioning. Prompt investigation, substantiation of potential and response to realized (actual) epidemiological risks associated with the extraordinary situation made it possible to prevent complications of the epidemiological situation in the territory of the tourist cluster of the Russian Federation.

Assessment of an Epidemic Urgency: Psychometric Evidence for the UCLA Loneliness Scale.

In modern industrialized countries, loneliness has been declared an epidemic. The present paper aimed to replicate previous findings about the dimensionality of the UCLA Loneliness Scale-3 version (LS-3) in a sample of Italian adults using Exploratory Structural Equation Modeling (ESEM). In Study 1, 1676 participants (Mage= 31.15; SD = 11.89) completed the LS-3. The three-factor ESEM model was performed to replicate the previous Italian version, and a Confirmatory Factor Analysis compared the three- and ten-item short versions. In Studies 2, 3, and 4, we administered measures of anxiety, depression, stress, internet addiction, self-esteem, and social interaction anxiety to 3513 participants (Mage= 30.81; SD = 11.77) to assess the convergent and discriminant validity of LS-3. The ESEM 3-factor model was replicated using a Target rotation (X2 = 847.597; df = 133; CFI = 0.942; TLI = 0.917; RMSEA = 0.062), whereas the already-known LS-3 short version raised psychometric concerns. Positive relationships with anxiety, depression, stress, internet addiction, and social interaction anxiety, as well as negative association with self-esteem were found. In conclusion, our findings support the use of the LS-3 in the Italian sample and discourage the administration of the current short forms. The implications for research and clinical practice have been discussed.

The development of the revised COPE 68 inventory with English and Slovak versions.

Although there have been several attempts at improving the COPE Inventory, the factor structure of the instrument is still in dispute. In addition, studies have shown low reliability coefficients for some of the first-order factors, with Mental Disengagement having the lowest factor loadings. In a recent study on the external validation of the instrument, two additional first-order factors were identified in the qualitative analysis, namely Self-care and Care for Others. Based on these arguments we created the Revised COPE 68 Inventory, changing some of the problematic items in the first order factor Mental Disengagement and adding items for the two new factors (Self-care and Care for Others). We then tested its reliability and performed factor analyses on the first and second-order factorial structure. The data were collected through social media in two languages, English and Slovak, using convenience and snowball sampling techniques. The English sample contained 834 participants with mean age 25.27 years (SD = 8.467) and the Slovak sample comprised 1,425 participants with mean age 33 years (SD = 14.59). For the statistical analyses we used Exploratory Structural Equation Model (ESEM) analyses with target rotation and WLSMV, Exploratory and second-order confirmatory factor analysis with the scores of the COPE Inventory and EFA. The Revised COPE 68 inventory had a good fit for all 17 first-order factors in both languages, including for the new factors Self-care and Care for Others. It appears that the first-order factors form a three-factor solution in both samples, consisting of active coping, social-emotional coping and avoidant coping. The revised Mental Disengagement has better psychometric properties as well. The Revised COPE 68 inventory was found to be a reliable multidimensional instrument for measuring various coping strategies in both the English and Slovak language versions.

Sampling‐based 3‐D line‐of‐sight PWA model predictive control for autonomous rendezvous and docking with a tumbling target

AbstractThis article introduces a line‐of‐sight (LOS)‐Euler rendezvous and docking (RVD) framework to dock with a tumbling target under several RVD constraints. By a double‐loop control scheme, the chaser's position is controlled to track the target's docking port which is coupled with its rotation. The chaser's attitude is driven to track the target's rotation, while satisfying the field of view constraintwhich is coupled with the LOS range. These complex couplings are linearly described in the proposed framework. To this end, the 6 DoF information interactions among the sensor measurements, states, and RVD constraints need no transformation and linearization. Consider the online piecewise affine (PWA) model predictive controller (MPC) may be unsolvable under complex constraints, which is caused by the accumulated prediction error, a sampling‐based method is proposed. The linear predictions are driven to the closer neighborhoods of the actual nonlinear states by constructing directional sampling intervals. Besides, a singularity free strategy is provided to realize continuous tracking with crossing the singularities of angle states. Detailed numerical simulations illustrate the validity of the proposed methods.