Relative Trajectory Research Articles

OTE-SLAM: An Object Tracking Enhanced Visual SLAM System for Dynamic Environments.

With the rapid development of autonomous driving and robotics applications in recent years, visual Simultaneous Localization and Mapping (SLAM) has become a hot research topic. The majority of visual SLAM systems relies on the assumption of scene rigidity, which may not always hold true in real applications. In dynamic environments, SLAM systems, without accounting for dynamic objects, will easily fail to estimate the camera pose. Some existing methods attempt to address this issue by simply excluding the dynamic features lying in moving objects. But this may lead to a shortage of features for tracking. To tackle this problem, we propose OTE-SLAM, an object tracking enhanced visual SLAM system, which not only tracks the camera motion, but also tracks the movement of dynamic objects. Furthermore, we perform joint optimization of both the camera pose and object 3D position, enabling a mutual benefit between visual SLAM and object tracking. The results of experiences demonstrate that the proposed approach improves the accuracy of the SLAM system in challenging dynamic environments. The improvements include a maximum reduction in both absolute trajectory error and relative trajectory error by 22% and 33%, respectively.

Automated Fiber Placement Path Planning and Analysis of Pressure Vessels.

The automated fiber placement (AFP) process faces a crucial challenge: the emergence of out-of-plane buckling in thermoplastic prepreg tows during steering, significantly impeding the quality of composite layup. In response, this study introduces a novel approach: the development of equations for wrinkle-free fiber placement within composite pressure vessels. The investigation encompasses a detailed analysis of prepreg trajectories in relation to shell geometry, accompanied by an in-depth understanding of the underlying causes of wrinkling on dome surfaces. Moreover, a comprehensive model for shell coverage, grounded in placement parameters, is meticulously established. To validate the approach, a simulation tool is devised to calculate press roller motions, ensuring the uniform fiber dispersion on the mandrel and achieving flawless coverage of the shell without wrinkles. This innovative strategy not only optimizes the AFP process for composite layup but also remarkably enhances the overall quality of composite shells. As such, this research carries significant implications for the advancement of composite manufacturing techniques and the concurrent improvement in material performance.

Corporate‐startup partnering: Exploring attention dynamics and relational outcomes in asymmetric settings

AbstractResearch SummaryStartups that partner concurrently with a large corporation must compete for the latter's attention. We extend the attention‐based view from an intraorganizational to an interorganizational context, exploring how startups differ in the amount of attention they receive, their actions to attract and sustain attention, and the impact of attention dynamics on the relational outcome of the partnership. Our research uncovers two separate contests for attention involving corporate and divisional managers, highlighting the distributed nature of attention. Reflecting these, our findings reveal how startups' responsiveness to the respective cognitive schemas and corresponding stimuli of corporate and divisional managers is critical to understanding their distinct relational trajectories and disparate outcomes. Our focus on attention is complementary to the focus on trust that has hitherto dominated research on relational dynamics.Managerial SummaryStartups partner with large corporations to access needed complementary resources. However, truly benefiting from such partnerships is challenging and requires them to attract as well as sustain the latter's attention. Our study reveals two contests for attention: one with corporate managers tasked with running a startup partnering initiative and the other with divisional managers in business units with whom actual commercial joint activity is forged. These two sets of managers have different priorities (schemas) that result in differences in the nature and amount of attention they pay to startups' actions (stimuli). Startups seeking corporate partnerships would do well to recognize this heterogeneity within large corporations and accordingly manage the attention–attraction process through suitable partner‐centric behaviors. On their part, large corporations need to be aware of and sensitive to the challenges such disparate schema of corporate and divisional managers pose for successful partnering outcomes as the relationship transitions from the early to later stages.

Coordination control of the automated fiber placement system using photogrammetry-based leader–follower approach

The use of multiple robots in an automated fiber placement system (AFPS) makes it possible to manufacture composite structures with complex shapes. The robots in such system usually adopt independent trajectory planning and control methods. This makes the AFPS lack coordination, and rely heavily on the high-precision calibration of the system when completing complex fiber placement tasks. In this article, a novel photogrammetry-based leader–follower (PBLF) approach is proposed for a particular AFPS which consists of a serial manipulator and a parallel robot to improve its accuracy and coordination. The approach is composed of an offline trajectory planning module, a leader module, and a follower module. The trajectory planning algorithm in the offline trajectory planning module solves the problem of robot workspace constraints and mandrel occlusion in the fiber placement tasks for complex structure. Besides, a novel photogrammetry-based pose tracking method is proposed to make the follower robot track its desired relative trajectory with respect to the moving reference frame and keep the coordination of the two robots. The theoretical stability of the proposed approach is proved. The results of experiments indicate that the proposed approach can reduce the average mean absolute errors of the relative pose in position and orientation direction by 62.15% and 46.42%, respectively. While the corresponding average root mean square errors are reduced by 61.20% and 45.26%, respectively. Therefore, compared with Non-Coordination approach, the PBLF approach can effectively improve the coordination of the two robots.

Vision-Based Target Tracking Controller Design for Asteroid Flyby Problem

An accurate target tracking system improves the quality of flyby imaging of the target and consequently aids effective planetary exploration. A vision-based tracking system is one of the more popular systems, utilizing imaging data to achieve the required tracking accuracy. However, recent high-accuracy target tracking requirements cannot be achieved with targeting error feedback only. This paper summarizes the asteroid flyby mission characteristics and requirements, shows how possible error sources in the tracking system, and displays an exemplar control system design. The tracking error source is generally divided into a navigation error, which is a tracking profile generation error, and a control error, which is caused by the control system. A high-quality onboard relative-trajectory determination system is required to improve the navigation accuracy of the control system, because the pre-designed or offline-estimated relative trajectory contains uncertainties that cause the tracking profile generation error. Previous studies focused on this navigation error because of its sensitive effect on control system performance, showing some methods for improvement. This paper discusses how the control system can be improved to achieve greater precision during target tracking by considering the navigation and system characteristics. A realistic case study scenario is defined and analyzed based on an actual target tracking interplanetary probe mission. The characteristics of the designed control system are presented and its performance is analyzed via numerical simulation, using the case study data.

Cross-sectional Developmental Trajectories of Executive Function and Relations to Theory of Mind in Autism Spectrum Disorder

Developmental executive function (EF) theories have proposed distinct domains of EF (cool and hot) but the EF development in autism spectrum disorder (ASD) has been assessed mainly with cool EF measures. Little is known regarding the development of hot EF in ASD. EF is suggested to strongly associate to theory of mind (ToM) in typical development but the correlation between hot EF and ToM is understudied in ASD. The current study was aimed at investigating the cross-sectional developmental changes of cool and hot EF in middle childhood and adolescence and their association to ToM in ASD. Eighty-two children and adolescents (7–16 years) were assessed with measures of cool EF (inhibition, working memory, planning, and cognitive flexibility), hot EF (affective decision-making and delay discounting), and ToM (2nd-order false belief and ignorance; mental state/emotion recognition). Our results showed that the trajectories of all cool EF presented linear age-related improvements in ASD. In terms of hot EF, trajectories demonstrated non-linear functions of age for affective decision-making and delay discounting. Both EF domains were found to associate with ToM over and above age, while hot EF associated with ToM over and above cool EF as well. The investigation of the developmental trajectories of cool and hot EF may help define potential cognitive phenotypes across age within ASD.

On the use of low-cost 3D stereo depth camera to drive robot trajectories in contact-based applications

In production systems characterized by small batches and high customization levels, operations are required to be flexible to adapt to different products within the shortest possible time and with the minimum effort for system setup. Contact-based operations such as surface finishing, polishing, deburring, and material deposition are mandatory in the fabrication of numerous products. To maintain consistent performance over time, many of these operations require a high level of accuracy, both in end-effector positioning and contact force level. This paper proposes a robotic solution to generate the robot working trajectory for contact-based operations over the external surface of unknown objects of which a digital model is not available or different from the actual state of the workpiece. The paper introduces the integration process of RGBD images to construct a 3D model and its elaboration to extract the workpiece. Different searching subroutines have been developed to select different areas of the workpiece based on the operation to be carried on and generate the related trajectory. The evaluation metric of the proposed robotic solution is given by the stability of the contact force exerted by the robotic tool and the error between generated and the actually followed trajectory due to the depth estimation of a low-cost camera. A few millimeters of the inaccuracy of the trajectory are obtained; these inaccuracies are compensated using force control. Different tests with different nominal values of the force control loop are carried out. Statistical analysis shows that the mean values of the contact force obtained coincide with the nominal value of the single tests.

Like and dislike scales in couples’ argumentative interaction

This study investigates regrading (Bilmes, 2019) as an argumentative resource in a Korean reality television show, Transit Love 2. The main concept of Transit Love 2 is that couples who have broken up join the dating show to either reunite with their ex-partners or to meet someone new. Focusing on argumentations about date invitations and relationship issues, this study shows how the participants launch like/dislike scales to justify why one should accept a requested date, restore a former relationship, and avoid sending an ex-partner to a new date. In the analysis, we illustrate the participants' ways of hearably going up and down on a scale and demonstrate how these scalar formulations shape the activities of managing accusatory, argumentative, and appeal-making talk. The findings of this study highlight that scalar regrades of like/dislike emotions are essential to the interactional activity of couples and have immediate consequences on their relational trajectories. This study contributes to a better understanding of how regrading is used in couple's argumentative discourse.

Applicability of Clohessy-wiltshire Model For Optimal Low-thrust Rendezvous

This paper investigates the applicability of the continuous thrust Clohessy-Wiltshire model for the optimal low-thrust rendezvous in the orbit. While simplifying the non-linear equations of relative orbital motion, certain assumptions were taken in account by Clohessy and Wiltshire to linearize the system of equations. When the same model is used for optimization of the trajectory of a relative transfer in the orbit using low-thrust, because of the assumptions in the dynamic model there are errors in the result which in turn depends upon the initial conditions for the optimal control problem. A study has been done to investigate the possible trend of error in the control input by varying the initial conditions for the relative transfer and comparing the results with those obtained using non-linear equations. Further, the trend of error in control input has also been studied by increasing the altitude of the target spacecraft orbit. Optimization of the relative motion trajectory has been performed to account for minimum propellant expenditure.

Optimal spatial-temporal cooperative guidance against a maneuvering target

This paper proposes an optimal three-dimensional (3-D) spatial-temporal cooperative guidance (STCG) law for intercepting a maneuvering target with impact angle and time constraints. The guidance problem is studied to achieve spatial cooperation for multi-directional attack in the normal channel and temporal cooperation for simultaneous interception in the tangential channel, respectively. Firstly, the 3-D optimal impact-angle-control guidance (OIACG) is introduced to formulate spatial interception geometry. Based on this law, the relative trajectory length is analytically derived and an accurate time-to-go predictor is formulated against maneuvering targets. In the tangential channel, an optimal temporal cooperative guidance is proposed by leveraging high-dimensional Schwarz inequality method. The proposed algorithm is believed to outperform the existing nonlinear cooperative guidance laws due to its optimality with specific performance index for minimizing the control expenditure. The convergence properties of the proposed STCG law are provided to facilitate its practical implementation. Comparison simulations and application under the realistic pursuer model and target estimation are performed to demonstrate the effectiveness and robustness of the proposed cooperative method.

Geodesics as Equations of Motion

The empirical description of the evolution of a physical system is the account of observed changes of state of the system in time, the measure of time being that of the Systeme International. To describe the Sun-Mercury system Einstein proposed a model based on the assumption that the evolution of the system, i.e. its relative space-time trajectory describes a geodesic on space-time endowed with the Schwarzschild metric. The evolution parameter of a geodesic is, however, an affine parameter or equivalently the proper time. However, the geodesic equation can be expressed in coordinate time. It has been shown that the solution of this equation reproduces the empirical evolution. A possiblee interptetation of the proper time is presented.

Polynomial Guidance for Impact-Time Control Against Maneuvering Targets

To address the issue of intercepting maneuvering targets at a specific time, a polynomial guidance method for impact-time control is proposed in this paper. Based on the relative virtual framework and the classical differential geometry curve theory, such method is divided into two parts: 1) the design of the relative trajectory-length-control (RTLC) guidance law against virtual stationary targets, and 2) the design of the prediction algorithms based on the guidance law or its characteristics. The former realizes RTLC, and the latter establishes the relationship between the desired relative trajectory length-to-go and the desired time-to-go, thus implementing impact-time control. Furthermore, based on the analytical properties of the guidance law in the relative arc-length domain, its performance, characteristics, and allowable impact time are analyzed. Finally, the effectiveness of the proposed guidance method and the validity of the theoretical findings are verified by numerical simulations results.

Russia-Pakistan Relations and the ‘China Factor’- Implications for India

As the Russia-Ukraine war enters a phase of attrition, Moscow is increasingly turning to the Global South for diplomatic support and ways to replenish its depleted resources. Likewise, given Pakistan’s grave economic situation and food crisis, the country is anxiously turning to Russia with open arms. This article examines the upward trajectory of relations between Moscow and Islamabad and analyses its implications for India. The article contends that although bilateral relations between Russia and Pakistan have their own dynamics, this confluence of interests takes on a completely new dimension when aligned with China. The war in Ukraine and the fluid global order have certainly complicated the geopolitical calculus in South Asia, and consequent reshuffling of positions may eventually push New Delhi away from Moscow.

Strategic Partnership between India and the United States: Examining Driving and Restraining Forces

This article aims to analyze the historical trajectory and current state of relations between India and the United States, spanning from India's independence in 1947 to the present, with a focus on identifying key stages of development, outcomes, and prospects. The establishment of a strategic partnership between the two countries has evolved through various phases, driven by economic, political, and ideological factors. However, certain limitations hinder the further deepening of this partnership, including disagreements on international political issues, India's pursuit of an independent foreign policy and reluctance to assume a subordinate role, inadequate US support on critical matters, and India's continued cooperation with Russia. Conversely, factors stimulating the growth of the strategic partnership encompass India's robust economic growth, its potential role as a counterbalance to China's expanding influence in Asia, shared interests in maintaining peace and stability in the Indo-Pacific region, mutual concerns about regional security, recent progress in nuclear policy agreements, and expanding avenues for cooperation in diverse domains. The article further examines the unique characteristics of India's relationship with the United States, which shape the nature of their existing strategic partnership, such as the shifting focus from the political and strategic realm to economic interactions, India's commitment to maintaining "strategic autonomy" and non-alignment in its deepening cooperation, its ability to differentiate between political partnership and economic collaboration, and the preservation of a multi-vector foreign policy approach. Based on the analysis, the authors assert that while a strategic military and political alliance between the two powers is unlikely in the near future, their relationship will continue to evolve within the framework of a strategic partnership. The findings of this study will provide insights for policymakers in the South and Southeast Asia region to anticipate developments and adjust their policies accordingly.

Simultaneous representation of multiple time horizons by entorhinal grid cells and CA1 place cells

Grid cells and place cells represent the spatiotemporal continuum of an animal's past, present, and future locations. However, their spatiotemporal relationship is unclear. Here, we co-record grid and place cells in freely foraging rats. We show that average time shifts in grid cells tend to be prospective and are proportional to their spatial scale, providing a nearly instantaneous readout of a spectrum of progressively increasing time horizons ranging hundreds of milliseconds. Average time shifts of place cells are generally larger compared to grid cells and also increase with place field sizes. Moreover, time horizons display nonlinear modulation by the animal's trajectories in relation to the local boundaries and locomotion cues. Finally, long and short time horizons occur at different parts of the theta cycle, which may facilitate their readout. Together, these findings suggest that population activity of grid and place cells may represent local trajectories essential for goal-directed navigation and planning.

Historical paths of black ethnic-racial identity in Brazil

The article deals with the historical paths of black ethnic-racial identity in Brazil. The text discusses the historical trajectory of the socio-racial relations of the black population in the 19th, 20th and 21st centuries from the perspective of building a black identity. In the 19th century, the Afro-Brazilian population encountered obstacles in building its own identity. In the 20th century, there was a more accentuated struggle for the construction of a black identity. In that century, identities called Sociological Subject (HALL, 2006), Resistance and Project (CASTELLS, 1999) were configured. In the 21st century there are advances in the construction of this identity due to the previous historical struggles of the black generations. The study points out the Resistance and Project identity models. The investigation consists of a descriptive-analytical study on the types of identities that coexisted and coexist in the process of Afro-Brazilian identity construction - from the 19th to the 21st century in the perspectives of Hall (2006; 2011) and Castells (1999; 2002), Elias (1994; 2001) and Goffman (1999; 2004). The study concludes that in each historical moment the Afro-Brazilian population built a singularity of identity in the light of delimited theorists.

Starling Formation-Flying Optical Experiment (StarFOX): System Design and Preflight Verification

The Starling Formation-Flying Optical Experiment (StarFOX) is intended as the first on-orbit demonstration of autonomous distributed angles-only navigation for spacecraft swarms. StarFOX applies the angles-only Absolute and Relative Trajectory System (ARTMS), a navigation architecture consisting of three innovative algorithms: image processing, which identifies and tracks multiple targets in images from a single camera without a priori relative orbit knowledge; batch orbit determination, which autonomously initializes orbit estimates for visible swarm members; and sequential orbit determination, which continuously refines the swarm state by fusing measurements from multiple observers exchanged over an intersatellite link. Nonlinear dynamics and measurement models provide sufficient observability to estimate absolute orbits, relative orbits, and auxiliary states using only bearing angles without maneuvers. StarFOX will be conducted using a four-CubeSat swarm as part of the NASA Starling mission, and simulations of experiment scenarios demonstrate that ARTMS meets mission performance requirements. Results indicate that mean bearing angle errors are below 35′′ (), initial target range errors are below 20% of true separation, and steady-state range errors are below 2% (). Absolute orbit estimation accuracy is on the order of 100 m. Hardware-in-the-loop tests display robust navigation under a variety of conditions, enabling autonomous, ubiquitous navigation with minimal ground interaction for future distributed missions.

Early development of electrophysiological activity: Contribution of periodic and aperiodic components of the EEG signal.

Brain function rapidly changes in the first 2 years of life. In the last decades, resting-state EEG has been widely used to explore those changes. Previous studies have focused on the relative power of the signal in established frequency bands (i.e., theta, alpha, and beta). However, EEG power is a mixture of a 1/f-like background power (aperiodic) in combination with narrow peaks that appear over that curve (periodic activity, e.g., alpha peak). Therefore, it is possible that relative power captures both, aperiodic and periodic brain activity, contributing to changes in electrophysiological activity observed in infancy. For this reason, we explored the early developmental trajectory of the relative power in theta, alpha, and beta frequency bands from infancy to toddlerhood and compared it with changes in periodic activity in a longitudinal study with three waves at age 6, 9, and 16 to 18 months. Finally, we tested the contribution of periodic activity and aperiodic components of the EEG to age changes in relative power. We found that relative power and periodic activity trajectories differed in this period in all the frequency bands but alpha. Furthermore, aperiodic EEG activity flattened between 6 and 18 months. More importantly, only alpha relative power was exclusively related to periodic activity, whereas aperiodic components of the signal significantly contributed to the relative power of activity in theta and beta bands. Thus, relative power in these frequencies is influenced by developmental changes of the aperiodic activity, which should be considered for future studies.

Public interest trends for Covid-19 and alignment with the disease trajectory: A time-series analysis of national-level data.

Data from web search engines have become a valuable adjunct in epidemiology and public health, specifically during epidemics. We aimed to explore the concordance of web search popularity for Covid-19 across 6 Western nations (United Kingdom, United States, France, Italy, Spain and Germany) and how timeline changes align with the pandemic waves, Covid-19 mortality, and incident case trajectories. We used the Google Trends tool for web-search popularity, and "Our World in Data" on Covid-19 reported cases, deaths, and administrative responses (measured by stringency index) to analyze country-level data. The Google Trends tool provides spatiotemporal data, scaled to a range of <1 (lowest relative popularity) to 100 (highest relative popularity), for the selected search terms, timeframe, and region. We used "coronavirus" and "covid" as search terms and set the timeframe up to November 12, 2022. We obtained multiple consecutive samples using the same terms to validate against sampling bias. We consolidated national-level incident cases and deaths weekly and transformed them to a range between 0 to 100 through the min-max normalization algorithm. We calculated the concordance of relative popularity rankings between regions, using the non-parametric Kendall's W, which maps concordance between 0 (lack of agreement) to 1 (perfect match). We used a dynamic time-warping algorithm to explore the similarity between Covid-19 relative popularity, mortality, and incident case trajectories. This methodology can recognize the similarity of shapes between time-series through a distance optimization process. The peak popularity was recorded on March 2020, to be followed by a decline below 20% in the subsequent three months and a long-standing period of variation around that level. At the end of 2021, public interest spiked shortly to fade away to a low level of around 10%. This pattern was highly concordant across the six regions (Kendal's W 0.88, p< .001). In dynamic time warping analysis, national-level public interest yielded a high similarity with the Covid-19 mortality trajectory (Similarity indices range 0.60-0.79). Instead, public interest was less similar with incident cases (0.50-0.76) and stringency index trajectories (0.33-0.64). We demonstrated that public interest is better intertwined with population mortality, rather than incident case trajectory and administrative responses. As the public interest in Covid-19 gradually subsides, these observations could help predict future public interest in pandemic events.

Still lacking self-reflection after all these years? (De)stabilizing factors of transatlantic relations according to German and US foreign policy experts between 2011 and 2017

This article compares the trends and theoretical positions found in the recent academic literature on the status and trajectory of transatlantic relations with the beliefs of 96 German and US foreign policy experts. The qualitative data are derived from open-ended in-depth interviews about the political, economic, and cultural factors that influence transatlantic cooperation and friction. Conducted in Berlin in 2011 and in Washington, D.C., in 2017, the interviews correspond with optimist and pessimist perceptions found in the academic literature and align roughly with realist, respectively, liberal/institutionalist and constructivist theoretical positions in International Relations theory and left/right political leanings. The study concludes with suggestions about the prospects for transatlantic relations, and the methodological benefits of comparing beliefs of foreign policy actors with theoretical paradigms and trends in the academic literature.