Desired Formation Research Articles

Distributed Formation Control Algorithms for QUAVs Based on Aggregative Games

In this article, the formation problems of multiple quadrotor unmanned aerial vehicles (QUAVs) are studied. In contrast to existing results, the problems are investigated from the perspective of aggregative games (AGs). An interesting discovery is that the desired formation can be constituted by the Nash equilibrium of a quadratic AG. To realize the desired formation for QUAVs, we design two distributed game-based formation algorithms. With the developed algorithms, the QUAVs do not need to measure the (relative) positions and (relative) velocities of neighboring QUAVs, which differs from existing algorithms. By constructing suitable Lyapunov functions, we rigorously analyze the two formation algorithms. The first formation algorithm converges exponentially to the desired formation for the QUAVs without parameter uncertainties. The other algorithm converges asymptotically to the desired formation, even if the QUAVs contain uncertain parameters. Finally, we provide illustrative examples.

Current and Future Opportunities for 3D Printing in Modern Board Games

Additive manufacturing (3D printing) is a set of disruptive technologies where parts are no longer produced by removing material until the desired form is achieved, but rather build the intended product layer by layer. With significant benefits in the efficient use of resources, optimizing performance, and allowing individual customization of each print, 3D printing techniques have been more widely adopted worldwide, and modern board games are no exception. However, until now its use is mostly hobbyists creating and sharing 3D models for improving player experience in two aspects: customization (upgrade) of game components, and solutions for organization/setup/logistics. Nevertheless, 3D printing opens opportunities also for game designers/developers and publishers. This paper presents a glimpse of the current use of 3D printing in modern board games and discusses opportunities for the future, highlighting how both players and professionals can take advantage of this technology.

Collision-Free Formation Control With Global Network Integrity Maintenance via Preserving Induced-Subgraph Connectivity

Network connectivity is a necessary prerequisite to realizing distributed formation control. However, it is challenging to maintain the global network connectivity of a formation with local information because the communications between topological agents may be disconnected as formation maneuvers due to the range-limited sensing capabilities of agents. In this article, we propose a novel connectivity-preserving formation strategy to address the challenge. The core idea is to decompose global connectivity constraint into the induced-subgraph-preserving problems of each agent. Different from the state-of-the-art methods, our strategy can acquire the local algebraic connectivity directly at the level of maximal cliques, instead of estimating the global algebraic connectivity by hundreds of iterations. Consequently, it yields more flexibility in formation maneuvers and requires lower computing costs. Moreover, we treat the entire formation as a single rigid body and employ a variant of the optimal reciprocal collision avoidance algorithm to optimize the overall movement of the formation so that agents can maintain the desired shape while avoiding obstacles. Here, the position and orientation of the desired formation are negotiated by the agents using only local peer-to-peer information. Simulation results verify that the proposed strategy can drive a group of agents to implement connectivity-preserving formations in obstacle-rich spaces.

Robust time‐varying formation control for uncertain multi‐agent systems with communication delays and nonlinear couplings

AbstractThis paper investigates the robust time‐varying formation control problems for a class of higher‐order multi‐agent systems subject to communication delays and heterogeneous uncertainties accounting for not only the parameter perturbations, nonlinearities and external disturbances occurring in the node local dynamics but also the nonlinear couplings in the interconnections of different nodes. For both cases of partially known and unknown time‐varying communication delays, we propose a unified formation control protocol, which incorporates a nominal controller to achieve the desired formation and a compensating signal to restrain the influences of uncertainties. Based on the signal compensation theory and Lyapunov–Krasovskii arguments, sufficient conditions to achieve the desired time‐varying formation are derived in terms of LMI. Thereafter, an explicit expression to describe the formation reference dynamics is yielded. Moreover, an algorithm is concluded to design the presented formation protocol in four steps. It is proven that the formation error can be made as small as desired under the designed controller despite the uncertainties and communication delays. Numerical simulation results are shown to demonstrate the effectiveness of our proposed control schemes.

Edge-Weighted Consensus-Based Formation Control with Collision Avoidance for Mobile Robots Based on Multi-Strategy Mutation Differential Evolution

An edge-weighted consensus-based formation control strategy is presented for mobile robots. In the edge-weighted strategy, a desired formation pattern is achieved by adjusting gain weights related to the distance between robots. Moreover, the edge-weighted formation control exploits the properties of weighted graphs to allow the formation to rotate and adapt its shape to avoid collision among robots. However, formation patterns are commonly defined by biases with respect to the centroid of the consensus rather than gain weights. This work proposes to optimize the gain weights in edge-weighted graphs, given a formation pattern in terms of biases. A multi-strategy mutation differential evolution algorithm is introduced to solve the optimization problem. Simulation and real-world experiments are performed considering multi-robot systems composed of differential drive robots. Additionally, the experimental setup includes Turtlebot3® Waffle Pi robots and an OptiTrack® motion capture system for control purposes. The experimental results verify the effectiveness of the proposed approach.

Fixed-Time Formation Tracking Control of Multiple Unmanned Surface Vessels Considering Lumped Disturbances and Input Saturation

This paper investigates the challenging problem of fixed-time formation trajectory tracking control for multiple unmanned surface vessels (USVs) affected by uncertain model dynamics, time-varying external ocean disturbances, as well as input saturation. Firstly, an adaptive super-twisting lumped disturbance observer (ASTLDO) is created by integrating high-order sliding mode with observer technology, which can accurately observe and compensate for the complex disturbance of the system within a finite time. Secondly, following the disturbance observer, backstepping technique, fixed-time control, and virtual leader–follower algorithm, the fixed-time formation tracking strategy is implemented. The proposed formation tracking control scheme enables the multiple surface vessels system to converge and maintain a stable desired formation in a fixed time, and the convergence time is independent of the initial states of the system. Furthermore, an adaptive auxiliary system is introduced to mitigate input saturation. In the end, the effectiveness and anti-interference ability of the suggested approach are confirmed by the formation simulation results of three USVs.

Detecting Bell Correlations in Multipartite Non-Gaussian Spin States.

We expand the toolbox for studying Bell correlations in multipartite systems by introducing permutationally invariant Bell inequalities (PIBIs) involving few-body correlators. First, we present around twenty families of PIBIs with up to three- or four-body correlators, that are valid for an arbitrary number of particles. Compared to known inequalities, these show higher noise robustness, or the capability to detect Bell correlations in highly non-Gaussian spin states. We then focus on finding PIBIs that are of practical experimental implementation, in the sense that the associated operators require collective spin measurements along only a few directions. To this end, we formulate this search problem as a semidefinite program that embeds the constraints required to look for PIBIs of the desired form.

Modelling agricultural innovations as a social-ecological phenomenon

Agricultural innovations involve both social and social-ecological dynamics where outcomes emerge from interactions of innovation actors embedded within their ecological environments. Neglecting the interconnected nature of social-ecological innovations can lead to a flawed understanding and assessment of innovations. In this paper, we present an empirically informed, stylized agent-based model of agricultural innovation systems in Mali, West Africa. The study aimed to understand the emergence of food security and income inequality outcomes through two distinct model structures: top-down, aid-driven (exogenous) innovation and bottom-up, community-driven (endogenous) innovation. Our research questions were: i) How does the inclusion of social-ecological interactions in the model affect food security and income inequality outcomes? ii) How do exogenous and endogenous mechanisms influence food insecurity and income inequality? iii) What are the conditions under which exogenous and endogenous mechanisms would improve food security? The structural design of the model was based on a combination of theory, empirics, and mapping of social-ecological dynamics within innovation systems. Using the Social-Ecological Action Situation framework, we mapped the social, social-ecological, and ecological interactions that jointly produce food security outcomes. The exploratory model analysis reveals three key insights: i) Incorporation of social-ecological interactions influences model outcomes. Scenarios with social-ecological interactions showed a stronger relationship between income inequality and food security, lower levels of food security, and higher levels of income inequality than scenarios with social interactions. ii) Endogenous mechanism leads to higher food security and income inequality than the exogenous mechanism. iii) Bidirectional outreach is more effective than unidirectional outreach in improving food security. Inclusion of social-ecological dynamics and interactions such as the role of climate risk perception, social learning and formation of innovation beliefs and desires is key for modelling and analysis of agricultural innovations.

DINAMIKA STRES SANTRI BARU DI PONDOK PESANTREN MODERN AL-IKHLAS LABUNTI KECAMATAN LASALEPA KABUPATEN MUNA

To find out how the dynamics of stress for new students at the Al-Ikhlas Labunti Modern Islamic Boarding School. This type of research is qualitative with a Narrative Inquiry research type. Based on the research results, several conclusions can be drawn: 1) The source of stress is in the form of unfulfilled desires (frustration), students' perceptions of their ability to adapt to the situation or demands of Islamic boarding schools, and environmental conditions including physical conditions in the form of dirty rooms, commotion, limited bathrooms , and the social environment in the form of lack of communication, quarrels, differences in habits experienced at home and at the Islamic boarding school, possessed by female students, use of private items without permission. 2) Symptoms of stress experienced by new students, namely, a) Symptoms of stress in the form of physical symptoms such as dizziness, difficulty controlling breathing and cold fingers. b) Psychological symptoms that occur are lack of confidence, loss of concentration, irritability, fear, hopelessness, difficulty controlling thoughts. c) Behavioral symptoms such as poor sleep quality, loss of appetite, lack of self-care and aggression. There is a follow-up impact of stress, namely: skipping lessons and escaping (running away). 3) Strategies for coping with stress for new students using emotional focused coping which includes Seeking social emotional support (talking to friends, ustadzah, Ustadz, parents, and getting closer to Allah), Positive reappraisal (thinking positively, being patient, praying, and being grateful) and Accepting responsibility (looking for ways to solve problems, accept responsibility and be able to adapt).

DINAMIKA STRES SANTRI BARU DI PONDOK PESANTREN MODERN AL-IKHLAS LABUNTI KECAMATAN LASALEPA KABUPATEN MUNA

To find out how the dynamics of stress for new students at the Al-Ikhlas Labunti Modern Islamic Boarding School. This type of research is qualitative with a Narrative Inquiry research type. Based on the research results, several conclusions can be drawn: 1) The source of stress is in the form of unfulfilled desires (frustration), students' perceptions of their ability to adapt to the situation or demands of Islamic boarding schools, and environmental conditions including physical conditions in the form of dirty rooms, commotion, limited bathrooms , and the social environment in the form of lack of communication, quarrels, differences in habits experienced at home and at the Islamic boarding school, possessed by female students, use of private items without permission. 2) Symptoms of stress experienced by new students, namely, a) Symptoms of stress in the form of physical symptoms such as dizziness, difficulty controlling breathing and cold fingers. b) Psychological symptoms that occur are lack of confidence, loss of concentration, irritability, fear, hopelessness, difficulty controlling thoughts. c) Behavioral symptoms such as poor sleep quality, loss of appetite, lack of self-care and aggression. There is a follow-up impact of stress, namely: skipping lessons and escaping (running away). 3) Strategies for coping with stress for new students using emotional focused coping which includes Seeking social emotional support (talking to friends, ustadzah, Ustadz, parents, and getting closer to Allah), Positive reappraisal (thinking positively, being patient, praying, and being grateful) and Accepting responsibility (looking for ways to solve problems, accept responsibility and be able to adapt).

Formation Control of Networked Mobile Robots With Unknown Reference Orientation

In this article, the distributed leader-following formation control problem of networked mobile robots is investigated. The desired formation is specified by a reference trajectory generated by the leader and the followers' desired relative positions with respect to the leader. On the one hand, for any security-aware multirobot systems, the values of the leader's position and orientation are generally not allowed to be transmitted via the inter-robot communication in the case of the information leakage of formation caused by the possible eavesdropping. On the other hand, relative orientations, different from relative positions, are typically difficult for mobile robots to measure directly, which makes the reference orientation unknown to all followers. In order to track the reference trajectory and form a desired formation in the absence of the reference orientation, followers are divided into two groups according to whether they are able to directly measure the relative positions with respect to the leader. The topology of the sensing/communication network among multirobot systems is described by a directed graph containing a directed spanning tree. Then, two observer-based control laws are proposed for two groups of followers, respectively, in both of which the unknown tracking errors are properly estimated. It is rigorously proven that the resulting closed-loop multirobot system is globally uniformly asymptotically stable. Finally, the effectiveness of our approach is illustrated by an experiment conducted on networked TurtleBot3 Burger mobile robots.

Centralized vehicle trajectory planning on general platoon sorting problem with multi-vehicle lane changing

Platooning of connected and autonomous vehicles has been extensively researched for its potential benefits in energy consumption, safety, comfort, traffic flow, and capacity. However, little attention has been given to the general platoon sorting problem of how to regulate the platoon to a desired formation and order. The problem poses a challenge as it involves multiple vehicles changing lanes in various directions, which makes them vulnerable to conflicts. This paper proposes a centralized trajectory planning method to address this problem. We construct a time–space-velocity network and formulate the problem as a multi-commodity flow model. To handle the large-scale network, we decompose the proposed model into several time-dependent least-cost path sub-problems using Lagrangian relaxation- and ADMM-based decomposition algorithms. Our method was tested through a series of experiments, which demonstrated its superiority in facilitating a faster and safer platoon sorting process compared to the existing method and achieving significant travel time savings at high traffic volumes compared to the simulations with SUMO.

The Relationship Between Self-Control and Learning Independence During the Covid-19 Pandemic

Independent learning is a form of desire and a sense of being able to learn on one's own accord, whether in the presence or absence of other people, to decide learning goals in terms of knowledge, skills, and attitudes in solving problems. Individuals who have good learning independence will have good self-control so that they can control their actions both consciously and unconsciously. This study aims to determine the relationship between self-control and learning independence during the Covid-19 pandemic in SMA Negeri 4 Pekanbaru students. This study involved 123 students of SMA Negeri 4 Pekanbaru who were selected using a stratified random sampling technique. The measuring tool used in this study is the self-control scale, which consists of 16 items compiled by Sari (2022). And the learning independence scale totals 11 items compiled by Sari (2022). Data analysis used the Spearman Rho correlation analysis technique, the results of the analysis test obtained a coefficient of r = 0.053. This explains that there is an insignificant positive relationship between self-control variables and learning independence in SMA Negeri 4 Pekanbaru students.

Effect of Ti‐metal addition on hot‐isostatically pressed (HIPed) Synroc‐C

AbstractSynroc, a candidate nuclear wasteform and Synroc technology, a waste treatment solution utilizing hot‐isostatic pressing (HIPing) have significant potential for the immobilisation of challenging nuclear wastes from both current and innovative reactors and fuel cycles. Hot isostatic press (HIP) consolidation is undertaken within sealed metal HIP canisters, where metal buffers (e.g., Ti, Fe and Ni) can be incorporated to control the redox environment within the canister. This study, for the first time, reports the effect of varying Ti‐metal addition (0, 2, 4, and 8 wt.%) on phase formation, microstructural characteristics, and wasteform performance for HIP consolidated Synroc‐C containing 20 wt.% simulated PUREX type (PW‐4b) high level waste. Quantitative X‐ray diffraction analysis, scanning electron microscopy‐energy dispersive X‐ray spectroscopy (EDS) and transmission electron microscopy‐EDS analyses were undertaken for analytical investigations. The chemical durability of the samples was assessed using ASTM C1220‐21 standard test. Hot‐isostatically pressed (HIPed) samples with 0 and 8 wt.% Ti added for redox control produced unfavourable phase formation. However, the HIPed samples with Ti additions of 2 and 4 wt.% as a redox buffer showed the desired phase formation of Synroc‐C without any significant change to the partitioning of waste elements among the phases along with compatible durability results, when compared to previous literature for hot uniaxial pressing (HUPed) or sintered materials.

Differentiator‐based bearing‐only formation control of quadrotors

AbstractThis article addresses the leader‐follower formation control problem for a group of quadrotors using only relative bearing measurements. Most existing methods require full position or velocity information, which cis challenging to obtain in harsh environments. In contrast, the proposed control scheme is based on a hierarchical system that does not rely on relative position or velocity measurements. The bearing‐only control law is designed to stabilize the desired formation, and each quadrotor maintains predetermined bearings with its neighbors. The control design relies on a non‐singular extraction algorithm for separate design of translation and rotation control. The outer loop of the control scheme utilizes a filter‐like approach to overcome the lack of bearing rate measurements in the bearing‐only formation controller. Moreover, employing differentiators following the separation principle with properties of asymptotic high accuracy, a uniform differentiator is provided for each following quadrotor to overcome the absence of linear velocity and acceleration feedback in the inner‐loop controller. Ultimately, the efficacy of the proposed control strategy is validated through a combination of Lyapunov stability theory and extensive numerical simulations.

Exploring barriers and facilitators to women's intention and behavior to seek treatment for distressing sexual problems.

Many women experience distressing problems with sexual functioning, most commonly in the form of low sexual desire or arousal, difficulties reaching orgasm, or genito-pelvic pain with sexual activity. Although effective treatments are available, more than half of the women who experience distressing sexual problems do not seek professional help. Understanding help-seeking patterns, experiences with treatment providers, and barriers to treatment is crucial to address this underutilization. Examining the role of personal characteristics, sexual problem symptoms, and cognitive factors in explaining the intention to seek treatment can help identify individuals who are most reluctant to seek help. Psychological online interventions are a promising resource to increase the availability of effective treatments. Knowledge about the predictors of women's intention to use internet-delivered treatments, as well as information about personal preferences regarding their scope, can help tailor them to women's needs. To address these research questions, cross-sectional data of 800 women (Mage = 30.49, range = 18-73) were analyzed. While many women considered clinical psychologists to be the most qualified treatment providers, gynecologists were cited as the most likely first point of contact. Among women not utilizing any treatments, many reported a preference for dealing with a sexual problem on their own as a reason not to seek help. Higher help-seeking intention was related to living in a larger city, experiencing higher sexual distress, experiencing pain or difficulties with vaginal penetration, higher self-stigma. and lower sexual assertiveness. Women who were convinced of the effectiveness of psychological online interventions and who appreciated the benefits of anonymity indicated that they were more likely to use them. Understanding what factors influence women's decisions about whether or not to seek professional help for distressing sexual problems is key to reducing the underutilization of available resources and developing treatments that meet their needs and preferences.

An Overview on 3D Printing of Structured Porous Materials and Their Applications

AbstractPorous materials play an essential role in chemical processes such as catalysis, adsorption, and in emerging technologies for electronic materials, light harvesting, and energy transfer. By far, zeolites have contributed most to industrial development. Other porous solid such as activated carbon, metal–organic frameworks, covalent organic frameworks, and porous coordination polymers also have been studied by researchers in the past two decades. The use of porous solids is set to grow in the future, and so is the need to fabricate them into more complex and diverse geometries for a variety of applications. Additive manufacturing, also known as 3D printing, has provided the possibility to shape the materials into desired forms, which offers many advantages over their traditional configurations. Structured catalysts, for example, can help to overcome the drawbacks of conventional packed catalyst bed‐like mass or heat transfer limitations and high pressure drop. This review focuses on the latest advances as well as the current challenges in 3D printing of the porous solids. This article aims to contribute to the shape engineering of porous solids and provide a better understanding of their formulations, structures, techniques, properties, and applications.

Clown doctors virtualized: hospital professionals’ perception regarding online visits during confinement in Portuguese public hospitals

Abstract Clown doctors’ artistic interventions directed to hospitalized children in the Portuguese public hospitals have been performed over the last 20 years, uninterruptedly. During the Covid-19 pandemic, the doctor clowns’ visits were interrupted, but soon after resumed in some hospitals, by means of visits online. The present study evaluates hospital professionals’ perception (n = 152) regarding clowns’ online visits. Participants were mostly nurses (n = 76), and child educators/teachers (n = 39) working in pediatrics (n = 139). Six months after the beginning of the visits, an online questionnaire was used to collect the data. A mixed-methods approach was used to analyse the data. Results indicate that most hospital professionals have a positive perception of online visits, considering that the quality of performance was preserved, and that children were engaged and benefited from the interactions. Moreover, participants acknowledge the organizations’ ability and promptness in developing an alternative way of visiting the children, even though some stressed that in-person visits are the most desirable format.

Finite-time ADRC formation control for uncertain nonaffine nonlinear multi-agent systems with prescribed performance and input saturation

AbstractThis paper explores finite-time formation control of multi-agent systems (MASs) with high-order nonaffine nonlinear dynamics and saturated input. Based on active disturbance rejection control theory, extended state observer is employed to identify unknown nonaffine nonlinear functions in MASs. The proposed control law consisting of backstepping control, tracking differentiator, and finite-time performance function is adopted for MASs to achieve the desired formation while reaching performance requirements. An auxiliary dynamic compensator is introduced to correct the control deviation caused by input saturation. Lyapunov stability theory is utilized to analyze the stability of the closed-loop system, which guarantees that the formation tracking error can asymptotically converge to an arbitrarily small neighborhood around zero in finite time. Finally, the simulation results show that compared to the adaptive, cooperative learning, and virtual structure methods, the proposed control algorithm has stronger tracking ability and faster setting time (1.8 s) under the influence of nonaffine nonlinear uncertainties. The integral square error for the formation control strategy in this paper is 0.16, which is much smaller than the abovementioned methods and is therefore provided to manifest the validity and feasibility of the proposed control strategy.

Angle-Constrained Formation Maneuvering of Unmanned Aerial Vehicles

In a global positioning system (GPS)-denied environment, unmanned aerial vehicles (UAVs) rely on local sensing-based formation maneuvering approaches for collective motion. To improve mission efficiency by reducing the total sensing requirements on all UAVs, this article proposes a leader–follower formation maneuvering framework with two leaders, where the followers will track the two leaders and maintain a desired angle-constrained formation with respect to the leaders using direction-only measurements, i.e., removing the need for inter-UAV distance measurements for the followers. To enable the UAV formation to maneuver in translation, rotation, and scaling simultaneously, the desired formation shape is specified by a set of interior angle constraints. By assigning each UAV’s yaw angle and position as the four controllable variables, an estimation-based attitude control algorithm is designed. For the UAVs’ position control, the designed formation maneuvering algorithm consists of a velocity tracking part and a formation shape control part that enables the first leader UAV to control the translational maneuvering, the second leader UAV to control the rotational and scaling maneuvering, and all the follower UAVs to maintain the formation shape. Simulations and experiments on UAVs’ formation maneuvering are conducted to illustrate the effectiveness of the proposed approach.