This paper addresses the connectedness issue in multiagent coordination, i.e., the problem of ensuring that a group of mobile agents stays connected while achieving some performance objective. In particular, we study the rendezvous and the formation control problems over dynamic interaction graphs, and by adding appropriate weights to the edges in the graphs, we guarantee that the graphs stay connected.

Distributed Coordination Control of Multiagent Systems While Preserving Connectedness

In the field of mobile robotics, the study of multi-robot systems (MRSs) has grown significantly in size and importance in recent years. Having made great progress in the development of the basic problems concerning single-robot control, many researchers shifted their focus to the study of multi-robot coordination. This paper presents a systematic survey and analysis of the existing literature on coordination, especially in multiple mobile robot systems (MMRSs). A series of related problems have been reviewed, which include a communication mechanism, a planning strategy and a decision-making structure. A brief conclusion and further research perspectives are given at the end of the paper.

https://journals.sagepub.com/doi/pdf/10.5772/57313

A Survey and Analysis of Multi-Robot Coordination

This book presents the separation-of-variables and T-matrix methods of calculating the scattering of electromagnetic waves by particles. Analytical details and computer programs are provided for determining the scattering and absorption characteristics of the finite-thickness slab, infinite circular cylinder (normal incidence), general axisymmetric particle, and sphere.The computer programs are designed to generate data that is easy to graph and visualize, and test cases in the book illustrate the capabilities of the programs. The connection between the theory and the computer programs is reinforced by references in the computer programs to equations in the text. This cross-referencing will help the reader understand the computer programs, and, if necessary, modify them for other purposes.

Light scattering by particles: Computational methods

We describe a framework for the design of collective behaviors for groups of identical mobile agents. The approach is based on decentralized simultaneous estimation and control, where each agent communicates with neighbors and estimates the global performance properties of the swarm needed to make a local control decision. Challenges of the approach include designing a control law with desired convergence properties, assuming each agent has perfect global knowledge; designing an estimator that allows each agent to make correct estimates of the global properties needed to implement the controller; and possibly modifying the controller to recover desired convergence properties when using the estimates of global performance. We apply this framework to the problem of controlling the moment statistics describing the location and shape of a swarm. We derive conditions which guarantee that the formation statistics are driven to desired values, even in the presence of a changing network topology.

Multi-Agent Coordination by Decentralized Estimation and Control

Collective control of a multiagent system is concerned with designing strategies for a group of autonomous agents operating in a networked environment. The aim is to achieve a global control objective through distributed sensing, communication, computing, and control. It has attracted many researchers from a wide range of disciplines, including the literature of automatic control. This paper aims to give a general framework that is able to accommodate many of these outcomes. Within this framework, the development on this topic is systematically reviewed and the representative outcomes can be sorted out from four aspects: 1) agent dynamics; 2) network topologies; 3) feedback and communication mechanisms; and 4) collective behaviors. Thus, the state-of-the-art approach and technology is described. Moreover, within this framework, further interesting and promising directions on this research topic are envisioned.

Overview: Collective Control of Multiagent Systems

We present a navigation function through which a group of mobile agents can be coordinated to achieve a particular formation, both in terms of shape and orientation, while avoiding collisions between themselves and with obstacles in the environment. Convergence is global and complete, subject to the constraints of the navigation function methodology. Algebraic graph theoretic properties associated with the interconnection graph are shown to affect the shape of the navigation function. The approach is centralized but the potential function is constructed in a way that facilitates complete decentralization. The strategy presented will also serve as a point of reference and comparison in quantifying the cost of decentralization in terms of performance.

/pdf/towards-decentralization-of-multi-robot-navigation-functions-im3zz2iwgy.pdf

Towards Decentralization of Multi-robot Navigation Functions

We develop decentralized cooperative controllers, which are based on local navigation functions and yield (almost) global asymptotic stability of a group of mobile agents to a desired formation and simultaneous collision avoidance. The formation could be achieved anywhere in the free space; there are no pre-specified final positions for the agents and is rendered stable both in terms of shape and in terms of orientation. Shape and orientation stabilization is possible because the agents regulate relative positions rather than distances with respect to their network neighbors. Asymptotic stability is provable and guaranteed, once the parameters in the local navigation functions are tuned based on the geometry of the environment and the degree of the interconnection network. Feedback controllers steer the agents away from stationary point-obstacles and into the desired formation using information that can be obtained within their sensing neighborhood and through communication with their network neighbors. The methodology is tested in simulation where groups of three and four mobile agents come into formations of triangles and diamonds, navigating amongst obstacles.

/pdf/formation-stabilization-of-multiple-agents-using-mm6jtp2gu0.pdf

Formation Stabilization of Multiple Agents Using Decentralized Navigation Functions

We demonstrate the principle of a bidirectional interaction between the perception model that describes the environment, and the sensor data collection that shapes the model, through the first automated scheme for sequential nuclear search. The objective is to detect and localize a weak radioactive point source, with consideration to the time spent for the search. Numerical simulations verify that desired false positive and false negative rates can be achieved using the control algorithm developed for deployment on prototype system. The simulation results are also consistent with previous theoretical, discrete simulation of the sequential search strategy that our continuous search control algorithm is based on.

/pdf/automated-sequential-search-for-weak-radiation-sources-uzkoer0vja.pdf

Automated Sequential Search for Weak Radiation Sources

An experiment was conducted at Horticulture Research Center of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut to study the correlation and path analysis of garden pea (Pisum sativum L.) by using 15 diverse genotypes. Correlation and path analysis furnish information regarding the nature and magnitude of various associates and help in measurement of direct effect of one variable on other. It is most important to know the direct and indirect effect on yield component for selecting suitable genotypes for improving the yield. Analyzed data of various parameters revealed that the genotypes, KS-205, KS-216, AP-5, KS-175 and KS-159 and the cross KS-156 x AP-1, KS-175 x AP-1 and KS-156 x Arkel gave promising results among all the genotypes and their crosses in relation to correlation and path analysis of garden pea.

Study of relationship between yield and yield Components in garden pea (Pisum sativum L.) by using correlation and path analysis

A homemade Static Light scattering studies has been used to determine angle resolved scattered intensity for different polarization states of the incident laser light. Classical light scattering set ups are being used to study morphological aspects of scatterers using simple set ups using low power lasers. Red blood cells form rather interesting as well as a challenging system for scattering experiments. The scattering spectrometer consists of a scattering arm, a scattering turn table and collimating arm. Along with polarizers integrated in the collimating arm as well as scattering arms ensures collection of scattered flux with the required polarization state. This technique is being developed for its in vitro studies using fresh red blood cells. A brief review of the theoretical models used for scattering from Red Blood Cells (RBC) has been discussed in the paper. Scattering pattern (scattering plots) as well as polar plots of scattered flux have been determined for different polarization state of the incident light. Insight into the orientation of major axis of particles can be inferred from the polar plots.

/pdf/static-laser-light-scattering-studies-from-red-blood-cells-1jsvzmsj6o.pdf

Amit Kumar

Papers

Towards Decentralization of Multi-robot Navigation Functions

Formation Stabilization of Multiple Agents Using Decentralized Navigation Functions

Automated Sequential Search for Weak Radiation Sources

Study of relationship between yield and yield Components in garden pea (Pisum sativum L.) by using correlation and path analysis

Static Laser Light Scattering Studies from Red Blood Cells