Formation Control Research Articles

Data-Driven Inverse Reinforcement Learning for Heterogeneous Optimal Robust Formation Control.

This article presents novel data-driven inverse reinforcement learning (IRL) algorithms to optimally address heterogeneous formation control problems in the presence of disturbances. We propose expert-estimator-learner multiagent systems (MASs) as independent systems with similar interaction graphs. First, a model-based IRL algorithm is introduced for the estimator MAS to determine its optimal control and reward functions. Using the estimator IRL algorithm results, a robust algorithm for model-free IRL is presented to reconstruct the learner MAS's optimal control and reward functions without knowing the learners' dynamics. Therefore, estimator MAS aims to estimate experts' desired formation and learner MAS wants to track the estimators' trajectories optimally. As a final step, data-driven implementations of these proposed IRL algorithms are presented. Consequently, this research contributes to identifying unknown reward functions and optimal controls by conducting demonstrations. Our analysis shows that the stability and convergence of MASs are thoroughly ensured. The effectiveness of the given algorithms is demonstrated via simulation results.

Adaptive time-varying enclosing formation control of underactuated surface vehicles with collision avoidance

Adaptive time-varying enclosing formation control of underactuated surface vehicles with collision avoidance

Binary peptide coacervates as an active model for biomolecular condensates

Biomolecular condensates formed by proteins and nucleic acids are critical for cellular processes. Macromolecule-based coacervate droplets formed by liquid-liquid phase separation serve as synthetic analogues, but are limited by complex compositions and high molecular weights. Recently, short peptides have emerged as an alternative component of coacervates, but tend to form metastable microdroplets that evolve into rigid nanostructures. Here we present programmable coacervates using binary mixtures of diphenylalanine-based short peptides. We show that the presence of different short peptides stabilizes the coacervate phase and prevents the formation of rigid structures, allowing peptide coacervates to be used as stable adaptive compartments. This approach allows fine control of droplet formation and dynamic morphological changes in response to physiological triggers. As compartments, short peptide coacervates sequester hydrophobic molecules and enhance bio-orthogonal catalysis. In addition, the incorporation of coacervates into model synthetic cells enables the design of Boolean logic gates. Our findings highlight the potential of short peptide coacervates for creating adaptive biomimetic systems and provide insight into the principles of phase separation in biomolecular condensates.

Fixed-time Formation Control for Leader-following Multi-agent Systems With Disturbances and Nonlinear Function Under Directed Topology

Fixed-time Formation Control for Leader-following Multi-agent Systems With Disturbances and Nonlinear Function Under Directed Topology

Formation Control of Multiple Rotorcraft Unmanned Aerial Vehicles With Nonlinear Flight Dynamics

Formation Control of Multiple Rotorcraft Unmanned Aerial Vehicles With Nonlinear Flight Dynamics

Ultrafast on-demand exciton formation in a single-molecule junction by tailored terahertz pulses.

The ultrafast manipulation of molecular states by charge transfer is essential for characterizing and controlling molecular dynamics. In this study, we demonstrated exciton formation in a single molecule through ultrafast electron tunneling processes between a molecule and a metal tip of a scanning tunneling microscope (STM) using a phase-controlled terahertz (THz) pulse. The pronounced luminescence of the well-defined molecular system under the distinct carrier-envelope phase of the THz pulse revealed that sequential state-selective electron-tunneling processes to the frontier molecular orbitals promoted ultrafast exciton formation in the molecule at the STM junction. Furthermore, ultrafast control of exciton formation was achieved using phase- and delay-controlled THz pulse pairs, providing a route for the regulation of molecular dynamics and the emergence of new molecular functions.

Employing Fuzzy Adaptive and Event-Triggered Approaches to Achieve Formation Control of Nonholonomic Mobile Robots Under Complete State Constraints

This article delves into the problem of fuzzy adaptive event-triggered (ET) formation control for nonholonomic mobile robots (NMRs) subject to full-state constraints. Fuzzy logic systems (FLSs) are employed to identify the unknown nonlinear functions within the system. To guarantee that all system states remain within their constraint boundaries, barrier Lyapunov functions (BLFs) are meticulously constructed. Subsequently, within the framework of the backstepping control design algorithm, we propose a novel fuzzy adaptive ET formation controller. Our ET mechanism can achieve an overall resource-saving rate of 88.17% for the four robots. Rigorous theoretical analysis demonstrates that the designed strategy not only ensures the stability of the controlled NMRs but also enables the formation tracking errors to converge to a small neighborhood around zero. Notably, the BLFs-based control approach presented herein endows the system with the capacity to avoid collisions to a certain degree, enhancing the overall safety and reliability of the robot formation. Finally, a simulation example is provided. The results vividly illustrate the effectiveness and practicality of the proposed theory, validating its potential for real-world applications in the field of nonholonomic mobile robot formation control.

Two-level anti-windup fast control of disturbed multi-agents with application to vehicles formation

This paper investigates the fast formation control problem of the multi-agent system (MAS) subject to practical input constraints and mismatched disturbances. An improved terminal sliding mode (TSM) control scheme, which incorporates finite-time disturbance observers (FTDOs) and a saturation level detecting system (SLDS), is proposed for a class of second-order MAS. More specifically, FTDOs effectively estimate both matched and mismatched disturbances in the motion equation of each agent, while the novel SLDS analyses the effect of input saturations and makes different dynamic modifications on both TSM surface and control law with respect to two (light or deep) saturation levels. The proposed two-level anti-windup TSM control theoretically guarantees the finite-time stability of MAS despite the presence of unknown mismatched disturbances and deep input saturations, which is practically applied to the formation control of unmanned ground vehicles with numerical simulations and physical experiments.

Impact of Chip Breaker Geometry on the Performance of Actively Rotary Monolithic Turning Tools.

The control of chip formation is a key aspect of modern turning operations, as improper chip formation can negatively affect tool life, surface quality, and overall machining efficiency. One approach to improving chip control is the integration of a chip breaker into the geometry of the cutting tool. This study examines the impact of chip-breaking geometry on the performance of monolithic rotary tools in active rotation turning. Two types of tools were compared: one without a chip breaker and another with an integrated chip breaker. The functionality of the chip breaker was experimentally validated, demonstrating its effectiveness in shaping chip segmentation under specific process parameters. Furthermore, tool wear, workpiece surface roughness, and cutting forces were evaluated. The findings indicate that the tool equipped with a chip breaker exhibits reduced wear while maintaining comparable surface quality. However, this benefit is accompanied by a slight increase in cutting forces.

Dynamic Consensus‐Based Formation Control With Output Mask Privacy for Multi‐Robot Systems

Dynamic Consensus‐Based Formation Control With Output Mask Privacy for Multi‐Robot Systems

Silver sulfadiazine therapy for the management of burns

Background: Burns are a significant global public health concern. There are approximately 180 000 burn-related deaths annually. This review analysed the characteristics of silver sulfadiazine (SSD) therapy and its effectiveness in treating moderate and severe burns. Method: This is a systematic review of studies published between 2018 and 2023, conducted using Google Scholar, PubMed and Science Direct. The search identified 4155 articles; 3708 were excluded based on titles and abstracts. After further screening, 10 full-text articles were analysed, including five randomised controlled trials, one cross-series study, one cross-sectional study and three experimental studies. Findings: The analysis indicated that SSD therapy is effective for second- and third-degree burns. Eight studies reported positive outcomes such as enhanced healing, granulation tissue formation and infection control. However, two studies noted limited effectiveness, highlighting the need for complementary treatments to optimise results. No severe complications were associated with SSD use, demonstrating its safety and reliability in burn care. Conclusions: SSD therapy is an effective and safe option for managing moderate and severe burns, often requiring additional treatments to maximise its benefits. Implications for practice: SSD therapy should be incorporated into burn treatment protocols, with additional therapies considered to enhance healing outcomes. Its effectiveness in infection control makes it a valuable option, particularly in resource-limited settings where advanced treatments may not be available. To optimise burn management, ongoing research and clinician training are essential in refining best practices and ensuring the most effective use of SSD therapy.

Comparative transcriptome analysis reveals potential regulatory genes involved in the development and strength formation of maize stalks

BackgroundStalk strength is a critical trait in maize that influences plant architecture, lodging resistance and grain yield. The developmental stage of maize, spanning from the vegetative stage to the reproductive stage, is critical for determining stalk strength. However, the dynamics of the genetic control of this trait remains unclear.ResultsHere, we report a temporal resolution study of the maize stalk transcriptome in one tropical line and one non-stiff-stalk line using 53 transcriptomes collected covering V7 (seventh leaf stage) through silking stage. The time-course transcriptomes were categorized into four phases corresponding to stalk early development, stalk early elongation, stalk late elongation, and stalk maturation. Fuzzy c-means clustering and Gene Ontology (GO) analyses elucidated the chronological sequence of events that occur at four phases of stalk development. Gene Ontology analysis suggests that active cell division occurs in the stalk during Phase I. During Phase II, processes such as cell wall extension, lignin deposition, and vascular cell development are active. In Phase III, lignin metabolic process, secondary cell wall biogenesis, xylan biosynthesis process, cell wall biogenesis, and polysaccharide biosynthetic process contribute to cell wall strengthening. Defense responses, abiotic stresses, and transport of necessary nutrients or substances are active engaged during Phase IV. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the two maize lines presented significant gene expression differences in the phenylpropanoid biosynthesis pathway and the flavonoid biosynthesis pathway. Certain differentially expressed genes (DEGs) encoding transcription factors, especially those in the NAC and MYB families, may be involved in stalk development. In addition, six potential regulatory genes associated with stalk strength were identified through weighted gene co-expression network analysis (WGCNA).ConclusionThe data set provides a high temporal-resolution atlas of gene expression during maize stalk development. These phase-specific genes, differentially expressed genes, and potential regulatory genes reported in this study provide important resources for further studies to elucidate the genetic control of stalk development and stalk strength formation in maize.

Fault-tolerant control of nonlinear quadrotor formation based on linear extended state observer and estimated minimum learning parameter

Fault-tolerant control of nonlinear quadrotor formation based on linear extended state observer and estimated minimum learning parameter

Global fixed-time position-constrained guidance and adaptive fuzzy prescribed performance control using novel shift function for multiple unmanned surface vehicles formation.

Global fixed-time position-constrained guidance and adaptive fuzzy prescribed performance control using novel shift function for multiple unmanned surface vehicles formation.

Neural observer-based fixed-time formation control of multiagent systems

Neural observer-based fixed-time formation control of multiagent systems

Predictor-based neural adaptive self-triggered quantitative prescribed performance formation control for underactuated unmanned surface vehicles

Predictor-based neural adaptive self-triggered quantitative prescribed performance formation control for underactuated unmanned surface vehicles

Adaptive Formation Control of Multiagent Systems Based on Ratio-of-Distance Rigidity

Adaptive Formation Control of Multiagent Systems Based on Ratio-of-Distance Rigidity

Safe Formation Control of Uncertain Multiagent Systems From a Bayesian Perspective

Safe Formation Control of Uncertain Multiagent Systems From a Bayesian Perspective

Data-driven adaptive formation control based on preview mechanism for networked multi-robot systems with communication delays

Data-driven adaptive formation control based on preview mechanism for networked multi-robot systems with communication delays

Fixed-time adaptive fuzzy formation control using novel nonlinear mapping function for multiple unmanned surface vehicles with fixed-time constraints

Fixed-time adaptive fuzzy formation control using novel nonlinear mapping function for multiple unmanned surface vehicles with fixed-time constraints