جستجوی مقالات مرتبط با کلیدواژه "multi-agent systems" در نشریات گروه "برق"

With the advancement of science, in many control methods, the neighbor system is used to better control and synchronize between different information of microgrids. There are problems in accessing and transmitting information through communication links. In this article, vulnerability and acceptance of secondary control methods are distributed. Also, denial-of-service (DoS) cyber-attacks, sensors and actuators, and hijacking on the island microgrid have been investigated. In addition to stability, synchronization is also analyzed in this article. Multi-agent systems have been used for synchronization. Cyber-attacks are mathematically formulated in the controller. A suitable controller is designed to eliminate the attacks. In the stability and synchronization of frequency and voltage, the Lyapunov function is presented and simultaneous analysis of stability and synchronization has been done with practical proofs. The resilience factor has been calculated for different attacks. It is shown that the system is resilient against cyber-attacks. A case study has been simulated in MATLAB/Simulink to approve the theoretical issues.

In many microgrid control methods, the output information of sensors and actuators of neighbouring distributed generators (DGs) is used to stabilize and synchronize voltage and frequency. Many problems such as disturbances, uncertainty, unmodeled dynamics, cyber-attacks, noise, time delay, and measurement errors cause invalid data problems and errors in the system. Better microgrid control depends on the quality of data measured or sent from the output of sensors and actuators. In this paper, according to the advantages of the Cooperative distributed hierarchical control, it is used for control and synchronization in the islanded microgrid with the presence of sensor and actuator error. To synchronize DGs with multi-agent systems and communication channels, it is modeled with graph theory. To stabilize and synchronize, sensor and actuator error in the DG model is mathematically formulated. In the proof of stability and synchronization, the appropriate Lyapunov candidate is presented and the conditions of stability and synchronization are proved. Finally, to show the effectiveness of the designed controller in solving communication channel problems and verifying the presented theory, a case study is simulated in the MATLAB/Simulink software environment with the presence of error and cyber-attack of sensors and actuators.

The problem of consensus in fractional order single-integrator multi-agent systems has been studied in this paper. The effect of memory is considered using the Riemann-Liouville fractional derivative in the dynamics of the agents. In order to achieve convergence among the agents, a fractional order control protocol based on the error signal between neighboring agents is proposed. Using Lyapunov's stability theorem, a Lyapunov function is introduced that shows that the agents converge over a specified settling time and the upper bound of the settling time is obtained. The merit of the proposed bound for the settling time is that it is independent of the initial conditions. Finally, some simulations are provided to confirm the introduced method.

Multi-agent systems are systems in which several agents accomplish a mission in a cooperative manner. In this paper, a novel idea for the construction of a movable runway platform based on multi-agent systems is presented. It is assumed that an aerial agent (quadrotor) decides to make an emergency landing due to reasons such as a decrease in energy level or technical failure, while there is no suitable platform for landing or the agent is not able to reach another place for landing. The goal is to create a specific formation pattern by a group of mobile robots that are smaller than the aerial agent, so that it can land on them. Each of the mobile robots is equipped with flat grid landing pad in its upper part so that when the robots approach each other and form a specific geometric arrangement (such as a pentagon), the landing pads are connected to each other and create a wider platform for landing. Cooperative control of agents (from aerial agent control to mobile robot formation control) is the main goal of this article, which is presented in different dynamic models under directed graph along with proof of Lyapunov-based stability analysis.

Today, in many control methods, neighboring system information is used for better control and synchronization between different units, and therefore, in the access and transmission of information through communication links, problems such as disruption, uncertainty, noise, delay, and cyber-attacks occur. In this paper, the effect of the Denial of Service (DoS) cyber-attack on the microgrid in island mode is investigated and a cooperative distributed hierarchical controller is designed with the presence of this cyber-attack. Distributed Generations (DGs) have been analyzed with the help of multi-agent systems and the communication network between them using graph theory. The effects of the DoS cyber-attack on the model of DGs are mathematically formulated and in proving the stability and synchronization of frequency and voltage, the suitable Lyapunov function is presented and the stability analysis of DGs against these cyber-attacks is performed and the stability and synchronization conditions of DGs are proved. To confirm the proposed theoretical issues, a case study model is simulated despite the DoS attack on the communicative links in Matlab Simulink, and the results show the performance of the designed controller in different conditions.

This paper considers the design of observer-based distributed adaptive controllers to achieve a leader-follower consensus for high-order nonlinear multi-agent systems in the presence of non-symmetric input saturation constraint and system uncertainties. Solving the consensus problem for nonlinear multi agent systems in the presence of unknown terms in the dynamics equations of follower that are due to model simplification, parameters uncertainty or external disturbances are investigated. In order to reduce the conservatism, the upper bound of uncertain term is considered to be unknown, which is obtained by adaptive laws. In addition, it is assumed that all states variables of agents are not directly measurable; therefore firstly, by designing the nonlinear distributed observers, the states variables of agents are estimated. Then, by using the sliding mode technique, the observer-based distributed adaptive control laws are designed to ensure the consensus between the agents, and the output of the followers can track the output of the leader, in the presence of non-symmetric input saturation and uncertain terms. Finally, the results of the simulations have completely confirmed the achievements of the proposed laws.

In this paper, the design of consensus control law in leader-follower multi-agent systems for agents with TS fuzzy dynamical model will be studied. In this study, assuming an event-triggered mechanism for updating the control signal of each agent, while reducing the number of control signal updates, the stability of the closed loop system is guaranteed. Each agent only sends data to other agents at the time of trigger, and its control input is updated only at the same time. The design of the control law and the event-triggered mechanism will lead to the solution of a system of linear matrix inequality. The innovation of the present study is in selecting fuzzy model for agents that can extend the solution of the consensus problem of multi-agent systems to more nonlinear systems. Finally, the effectiveness of the proposed method is shown through a numerical example.

This paper, studies the controller design for containment problem for a class of multi-agent systems with identical time-invariant continuous-time nonlinear dynamics and fixed directed communication graph. In this problem, the lyapunov stability theorem, the graph theory and matrix linear inequality are used. The agents are divided into two groups of leaders and followers. In containment problem, all the followers are controlled under which will asymptotically converge to the convex hull spanned by the leaders so distributed communication protocol with fixed time delay is considered and four-step algorithm is proposed for obtaining parameters and gain matrix. The above case is proved to be sufficient condition under theorem. To illustrate the reliability and efficiency of the proposed method, numerical example with simulations are presented.

Bearings only tracking is a challenging issue with many applications in military and commercial areas. In distributed multi-sensor multi-target bearings only tracking, sensors are far from each other, but are exchanging data using telecommunication equipment. In addition to the general benefits of distributed systems, this tracking system has another important advantage: if the sensors are sufficiently spaced apart, the target state is observable and the maneuver is not necessary by sensors. In this work, Multi-sensor multi-target bearings only tracking with decentralized architecture and asynchronous measurements is newly proposed. In this study, with the help of the idea of ​​composite measurements and taking into account the time of measurements in the calculations, while overcoming the asynchronous of the measurements, the nonlinear effects in the measurement equation are also eliminated. Also, diffusive filtering is used to exploit the information of neighboring sensor agents to improve the estimates. The simulations show that the system designed in this research can well detect targets and track them with acceptable accuracy.

In this paper, the leader-following group consensus of discrete-time fractional-order multi-agent systems with time-delay is studied. At First, two groups are considered. Then, the problem is extended to arbitrary number of groups. The agents are considered as discrete-time fractional order integrators with input time delay . The interaction between agents is described with a directed communication graph with fixed topology. The group consensus problem for the considered agents leads to asymptotic stability analysis of a discrete-time fractional order system with time-delay. Based on this idea, the necessary and sufficient condition to reach the leader-following group consensus in terms of the controller gains of agents is extracted. Moreover, the optimal value of the controller gains is calculated to minimize a special performance index. Numerical simulations show the performance of the proposed method.