This paper studies the leader-following consensus problem of second-order multi-agent systems with directed topologies. By employing the asynchronous sampled-data protocols, sufficient conditions for leader-following consensus with both constant velocity leader and variable velocity leader are derived. {Leader-following quasi-consensus can be achieved in multi-agent systems when all the agents sample the information asynchronously.} Numerical simulations are provided to verify the theoretical results.
The simultaneous problem of consensus and trajectory tracking of linear multi-agent systems is considered in this paper, where the dynamics of each agent is represented by a single-input single-output linear system. In order to solve this problem, a distributed control strategy is proposed in this work, where the trajectory and the formation of the agents are achieved asymptotically even in the presence of switching communication topologies and smooth formation changes, and ensuring the closed-loop stability of the multi-agent system. Moreover, the structure and dimension of the representation of the agent dynamics are not restricted to be the same, as usually assumed in the literature. A simulation example is provided in order to illustrate the main results.
In this paper, we consider a multi-agent consensus problem with an active leader and variable interconnection topology. The dynamics of the active leader is given in a general form of linear system. The switching interconnection topology with communication delay among the agents is taken into consideration. A neighbor-based estimator is designed for each agent to obtain the unmeasurable state variables of the dynamic leader, and then a distributed feedback control law is developed to achieve consensus. The feedback parameters are obtained by solving a Riccati equation. By constructing a common Lyapunov function, some sufficient conditions are established to guarantee that each agent can track the active leader by assumption that interconnection topology is undirected and connected. We also point out that some results can be generalized to a class of directed interaction topologies. Moreover, the input-to-state stability (ISS) is obtained for multi-agent system with variable interconnection topology and communication delays in a disturbed environment.
This paper investigates the high-order consensus problem for the multi-agent systems with agent's dynamics described by high-order integrator, and adopts a general consensus algorithm composed of the states' coordination control. Under communication delay, consensus algorithm in usual asynchronously-coupled form just can make the agents achieve a stationary consensus, and sufficient consensus condition is obtained based on frequency-domain analysis. Besides, a predictor-based consensus algorithm is constructed via multiplying the delayed neighboring agents' states by a delay-related compensation part. In our proposed algorithm, a compensating delay is introduced to match the communication delay. Specially, the original high-order consensus is regained when the compensating delay equals to the communication delay, but cannot be achieved if the compensating delay is not equivalent to the communication delay. Moreover, sufficient consensus convergence conditions are also obtained for the agents under our predictor-based algorithm with different compensating delay. Numerical studies for multiple quadrotors illustrate the correctness of our results.
In this paper, we investigate multi-agent consensus problem with discrete-time linear dynamics under directed interaction topology. By assumption that all agents can only access the measured outputs of its neighbor agents and itself, a kind of distributed reduced-order observer-based protocols are proposed to solve the consensus problem. A multi-step algorithm is provided to construct the gain matrices involved in the protocols. By using of graph theory, modified discrete-time algebraic Riccati equation and Lyapunov method, the proposed protocols can be proved to solve the discrete-time consensus problem. Furthermore, the proposed protocol is generalized to solve the model-reference consensus problem. Finally, a simulation example is given to illustrate the effectiveness of our obtained results.
In this paper, a novel consensus algorithm is presented to handle with the leader-following consensus problem for lower-triangular nonlinear MASs (multi-agent systems) with unknown controller and measurement sensitivities under a given undirected topology. As distinguished from the existing results, the proposed consensus algorithm can tolerate to a relative wide range of controller and measurement sensitivities. We present some important matrix inequalities, especially a class of matrix inequalities with multiplicative noises. Based on these results and a dual-domination gain method, the output consensus error with unknown measurement noises can be used to construct the compensator for each follower directly. Then, a new distributed output feedback control is designed to enable the MASs to reach consensus in the presence of large controller perturbations. In view of a Lyapunov function, sufficient conditions are presented to guarantee that the states of the leader and followers can achieve consensus asymptotically. In the end, the proposed consensus algorithm is tested and verified by an illustrative example.
The leader-following consensus of multiple linear time invariant (LTI) systems under switching topology is considered. The leader-following consensus problem consists of designing for each agent a distributed protocol to make all agents track a leader vehicle, which has the same LTI dynamics as the agents. The interaction topology describing the information exchange of these agents is time-varying. An averaging method is proposed. Unlike the existing results in the literatures which assume the LTI agents to be neutrally stable, we relax this condition, only making assumption that the LTI agents are stablizable and detectable. Observer-based leader-following consensus is also considered.
Catastrophic impact of floods is the result of an interaction between extreme hydrologic events and environmental, social and economic processes. Therefore, an integrated approach to flood management plays an important role in sustainable development. Such an approach requires a team comprising experts from the fields of hydrology and water resources, nature protection, risk management, human security, municipalities, economics and land use. The estimations of experts can serve for finding a solution to specific YES/NO problems and for estimating the value of specific attributes or parameters. In order to measure and evaluate the level of agreement between experts, a newly developed method for assessing the level of agreement and the value of τ-agreement, based on the Shannon theory of entropy, was applied. The use of such fuzzy-group-agreement decision making procedure, involving a broad range of stakeholders, is illustrated by the Flood Control Case Study, Zarosice, Czech Republic. In the case study of the Zdrava Voda catchment, where a part of the urbanised territory of the Zarosice village suffered from periodical flooding, a group of experts analysed the catchment data, focusing particularly on designed rainfall data. The KINFIL model was subsequently applied. and Katastrofální dopad povodní je výsledkem vzájemné interakce extrémních hydrologických událostí a environmentálních, sociálních a ekonomických procesů. Z tohoto důvodu je integrovaný přístup k řešení protipovodňové ochrany důležitou součástí trvale udržitelného rozvoje. Tento přístup vyžaduje tým odborníků z oborů hydrologie a vodního hospodářství, ochrany přírody, řízení rizik (risk managementu), bezpečnosti osob, samosprávy, ekonomiky a hospodářského využití půdy. Názory těchto odborníků slouží k nalezení odpovědi na specifické otázky typu ano/ne, případně ke stanovení přesných hodnot parametrů. Pro měření a vyhodnocení konsenzu odborníků je použita nová metoda pro stanovení míry souhlasu a hodnoty τ-agreement vycházející z Shannonovy teorie entropie. Metoda je popsána na případové studii prováděné v části katastru obce Žarošice, která je často zaplavována. Tým expertů, zahrnující široké spektrum zainteresovaných subjektů, se zaměřil na dostupné informace o povodí, zejména na návrhové srážky, které byly následně vstupem do matematického srážko-odtokového modelu KINFIL.
Príspevok sa zaoberá analýzou konceptu validity a hľadaním dôvodov absencie konsenzu v jej definovaní a vnímaní. Najvýznamnejšie koncepcie validity sú konfrontované z diachronického hľadiska s dôrazom na konceptuálne a epistemologické otázky. Táto analýza naznačuje, že rozdiely medzi jednotlivými koncepciami validity nie sú terminologickými hrami, ale majú vecné dôsledky. Zároveň je demonštrované, že význam aj tej najužšej a najčastejšie uvádzanej definície (test je validný, ak meria to, čo má merať) závisí na niekoľkých voľbách, ktoré sú v zásade arbitrárne. Tie následne implikujú empirické postupy potrebné pre atribúciu prívlastku „validný“ a v konečnom dôsledku aj to, či by mala byť validita považovaná za relačný alebo kauzálny koncept., The article discusses the concept of validity and explores the reasons for the absence of a widespread consensus in its definition and perception. Applying a diachronic perspective, the most influential conceptions of validity are being confronted with an emphasis on both conceptual and epistemological issues. Based on that analysis, it is argued that differences between several conceptions of validity are not just a terminological quibble. Furthermore, it is demonstrated that the meaning of even the simplest and mostly cited definition (a test is valid if it measures what it purports to measure) depends on some choices that are in fact arbitrary. These choices made further imply the epistemological procedures needed for the attribution of the "validity" label and whether validity should be considered a relational or a causal concept., Ivan Ropovik., and Obsahuje seznam literatury