Affine Formation Maneuver Control for Multiagent Systems Based on Unknown Input Reconstruction

Formation control for nonlinear multi-agent systems by robust output regulation

In this paper, the bipartite containment control problem of multi-agent systems (MASs) with unknown disturbances is studied. At first, a signed undirected graph is used to describe the Cooperative-Antagonistic interaction among the agents. Different from some conventional results of convergence in the infinite time domain, the control protocol proposed in this paper achieves the fixed-time convergence, and applies the fixed-time control and bipartite consensus to the containment control, making the proposed control protocol more practical. In addition, this paper also considers the existence of external disturbances and a novel fixed-time bipartite containment control protocol is proposed to eliminate them. Then, the stability analysis under the control protocol is completed by using the Lyapunov theory and mathematical theorem. Finally, the effectiveness of the proposed control scheme is verified by some simulation examples.

This article presents a new approach to estimation of unknown inputs and faults in a class of nonlinear systems. The approach is based on the design of a cascade connection of two sliding mode observers. The first is used for estimation of state and unknown inputs and the second is used for fault detection. An important feature of the proposed approach is that the state trajectories do not leave the sliding manifold even in presence of unknown disturbances and faults. This allows for faults and disturbances to be reconstructed based on information retrieved from the equivalent output injection signal. The proposed approach is used to reconstruct unknown disturbances and faults in nonlinear model of Vertical Take-Off and Landing (VTOL) aircraft system.

In recent years, there have been an increasing number of achievements dealing with the control of agent formations (Olfati-Saber, 2006; Tanner & Jadbabaie, 2007; Fax & Murray, 2004; Jadbabaie et al., 2003; Lin et al., 2004; Olfati-Saber & Murray, 2004). The formation control of multiple moving agents has emerged as a topic of widespread interest due to its broad range of applications in military missions, environmental surveying, and space missions. Multiple mobile autonomous agents coupled with each other through interactions can generate certain ordered behaviors, such as aggregation, cohesion, alignment, rotation and synchronization (Fax & Murray, 2004; Jadbabaie et al., 2003; Lin et al., 2004; Olfati-Saber & Murray, 2004). Among the typical approaches to formation control, distributed control strategies have aroused researchers’ outstanding attention because there is no centralized supervisor and only a little sense of communication information is needed. Recently, there has been a tendency to deal with the formation control as a consensus problem. In the multiagent systems, consensus means to reach an agreement by means of an interaction rule that specifies the information exchange between an agent and its neighbors (Fax & Murray, 2004; Jadbabaie et al., 2003; Lin et al., 2004; Olfati-Saber & Murray, 2004). Fax & Murry (Fax & Murray, 2004) analyzed the stability of the formation control with first-order consensus protocols based on the graph Laplacian. Jadbabaie et al. (Jadbabaie et al., 2003) demonstrated the results of the alignment problem which is concerned with reaching an agreement without computing any objective functions. Lin et al. (Lin et al., 2004) studied three formation strategies for groups of mobile autonomous agents with local communication topology. Moreover, by using a Lyapunov-based approach, Olfati-Saber & Murry (Olfati-Saber & Murray, 2004) solved the consensus problems in networks of agents with directed interconnection graphs and time delays. The key idea involved in nonlinear formation control is to preserve the inter-agent distances from decaying to zero during the motion for the purpose of collision avoidance. In the formation control, tracking control problems of multi-agent systems are studied increasingly, and many results have been obtained with nearest neighbor-based rule (Hong et al., 2006; Anderson et al., 2007; Chen & Tian, 2009). Hong et al. (Hong et al., 2006)

Bipartite time-varying formation group containment control for multi-agent systems based on multi-layer network and semi-signed directed graph

This paper investigates the adaptive distributed synchronization control problem of multi-agent systems, where the information transmission in the network is subject to unknown constant signal transmission delay. Firstly, an adaptive distributed control scheme is designed for a class of certain multi-agent systems to guarantee the synchronization among all agents is achieved. In the scheme, the unknown constant delay can be estimated online. Furthermore, compared with some existing works where some global information are required to design the controllers for the agents, the scheme proposed in our paper does not need the global information. By algebraic graph theory with Lyapunov stability theory, the whole closed-loop system stability analysis is provided. Then, the method is extended to a class of uncertain nonlinear MASs. Finally, genetic regulatory networks (GRNs) are used to show the effectiveness of the proposed design scheme.

Observer-based distributed adaptive fault-tolerant containment control of multi-agent systems with general linear dynamics

This article investigates the iterative learning control problem for a class of nonlinear heterogeneous multi-agent systems. The main contribution of this article is to apply iterative learning control algorithm to the multi-agent systems with multiple leaders, and solve the containment control problem of multi-agent systems in the sense of iterative learning control stability. Based on the framework of communication topologies, distributed iterative learning controllers are designed. And when the iterative learning control laws are applied to the systems, the containment errors between the followers’ states and the convex hull spanned by the leaders’ states over a finite-time interval are bounded, and furthermore, the containment errors can converge to zero as the iteration index approaches to infinity in the absence of initial errors. A simulation example is finally constructed to verify the effectiveness of the theoretical method.

This paper investigates event-triggered control strategy for the consensus problem of multi-agent systems with time-varying delays. The state of each agent is sampled and transmitted to its neighbors when a certain event condition is satisfied. Two kinds of decentralized event conditions are proposed. Sufficient conditions in terms of Linear Matrix Inequalities (LMIs) are established to ensure the consensus of the multi-agent systems with the event-triggered control feedbacks. Simulation example is given to demonstrate the effectiveness of the theoretical results.

Safety control using barrier certificates for multiagent systems with input saturation and formation constraints

This paper investigates the tracking control problem of multiagent systems with Lipschitz nonlinearities and external disturbances that track a target with states that are not available to any of the agents. For this purpose, a distributed estimation and control algorithm (DECA) is firstly designed for each agent to estimate and track the target’s states. Then, the proposed DECA is extended based on a finite time disturbance estimator for tracking control in the presence of external disturbances. The stability analysis of suggested algorithms is also considered. Simulation examples illustrate the promising performance of the proposed algorithms.

Joint unknown input observer for descriptor system based on interval observer

This paper considers the formation control problem of Multi-Agent systems in two-dimension plane. A three-layer formation control architecture is proposed for each Agent in the formation team. The author defines a vector and a matrix to represent the formation trajectory and formation shape of the whole team, respectively. The leader Agent tracking the formation trajectory, whereas all the follower Agents tracking their desired trajectory derived based on moving trajectory of leader Agent and formation shape matrix. Simulations are made in three case, standard formation control, formation control under formation trajectory switching and formation control under switching of both formation trajectory and formation shape. Results are included to verify the realizability and flexibility of the proposed three-layer formation control architecture.

The intelligence security control problem of multiagent systems in the presence of actuator faults is investigated against denial-of-service (DoS) attacks. Noticing that the DoS attacks usually make the actuator signal not available for distributed control protocols, a novel intelligence dual-eventtriggered control strategy is developed to eliminate the impact of DoS attacks. This control strategy includes two related event triggers respectively set on different channels, in which the second event-triggered condition is related to the triggering sequence of the previous event. Through the coordination between two nested event triggers set on different channels, the controller is avoided by being affected by wrong signals caused by DoS attacks. The developed distributed control protocol can not only guarantee the realization of the tracking control task but also ensure that no ‘Zeno behavior” occurs in the process of the event triggering. Moreover, the obtained results are applied to the mobile robot systems. Finally, a numerical simulation example and a mobile robot system application are given to verify the feasibility and effectiveness of the proposed control strategy.

This paper investigates the distributed containment control problem for multi-agent systems with general linear dynamics under a directed graph. A new observer based on the relative outputs of neighboring agents is developed to estimate the relative states of neighbors which avoid designing the observer for the leaders in the existing literature. A matrix transformation is introduced to eliminate the coupling terms resulting from the simultaneous design of the observer and the controller gains. Then a sufficient condition on the existence of the observer-based controllers is presented in terms of strict linear matrix inequalities. Finally, a simulation example is provided to demonstrate the effectiveness of the proposed design method.