Nonfragile robust [formula omitted] containment control for multi-agent systems with a time-varying delay

Finite-time coordinated formation control of discrete-time multi-AUV with input saturation under alterable weighted topology and time-varying delay

Consensusability of multi-agent systems with time-varying communication delay

Containment control of heterogeneous multi-agent systems

Stable Teleoperation with Time Domain Passivity Approach

This paper considers the containment control of linear multi-agent system with weakly connected information topology. By defining the node-induced strongly connected subgraph as strong component, the agents contained in strong components with zero in-degree are called leaders and the others are called followers. Then, a sufficient and necessary condition is proposed for all agents to achieve containment by employing an observer-based protocol, where all followers finally converge to the convex hull formed by leaders and each strong component of leaders asymptotically achieve consensus. Since the number of leader agents in each strong component are always larger than one, the proposed scheme is more robust for the malfunction of leaders. Further, two LMIs are given to design the observer-based protocol. Numerical examples are included to illustrate the validity of the proposed results.

This paper studies the problem of determining sensor locations in a large sensor network using only relative distance (range) measurement. In this paper, we consider a synchronous communication protocol when 1) the communication delay between sensors is uncertain; 2) successive packet loss is finite. Based on the barycentric coordinate representation, our work generalizes the DILOC algorithm in the communication environment with time delays and packet loss. First, a synchronous communication protocol is developed, and the distributed localization algorithm is mathematically modeled as a linear difference equation with time-varying communication delays. Next, the time-varying-delay model is proved to be globally convergent to the true coordinates under consensus framework with quotient graphic theory. Finally, simulation examples are provided to demonstrate the effectiveness of the theoretical result.

In this paper, time-varying formation tracking problem for second-order nonlinear multi-agent systems with time-varying communication delays has been investigated, where the followers maintain a predefined time-varying formation while tracking the moving leader. Based on a distributed observer, a formation tracking protocol with time-varying delay is developed using the relative neighboring information. By constructing the Lyapunov-Krasovskii (L-K) function, sufficient conditions have been obtained to guarantee the stability of time-varying formation tracking. In addition, the unknown gain matrix in the proposed protocol is computed out through the technique of variable substitution. Numerical simulation results are presented to validate the effectiveness of our theoretical analysis.

This paper investigates an observer-based control strategy for networked multi-agent systems with general linear dynamics and time-varying communication delays in a sampling setting. The communication topology is assumed to be directed fixed. Different from a traditional observer-based controller for a single system, the objects that need to be observed here are the state differences between an agent and its neighbours. Using a system transformation method, some equivalent conditions concerning the consensus of multi-agent systems are established. Moreover, we prove that both the connection weights and the communication topology play an important role in the study of multi-agent systems, and establish a linear matrix inequality based observer design method.

In this article, the adaptive consensus tracking control is developed for uncertain multiagent systems with time-varying state delay in the case that leader's state is accessible at sampling instants. By proposing a distributed sampled observer with hybrid form, adaptive tracking controller with the complementary term is designed for first-order multiagent systems, and then is extended to high-order multiagent systems with the aid of dynamic surface control. Through the complementary term, the effects of parameter estimation error as well as dynamical terms with time-varying delays are eliminated and thus less conservative condition on time delays is required. It is proved that, under criteria in terms of linear matrix inequalities (LMIs), tracking error and estimation error exponentially converge to zero for first-order systems, and to a sufficiently small neighborhood of zero for high-order systems.

Passivity theory is a very useful tool for the stability analysis of bilateral teleoperation with communication delay. Many researchers use passivity-based stabilization method such as those based on scattering theory or wave variables. However, passivity-based stabilization is too conservative for the design of a high-performance teleoperation system. The term “high-performance” implies that people who operate this system can experience a highly accurate reaction force from environments. In this study, we analyze the L2-stability of some bilateral control systems with time-varying communication delay by using the small-gain theorem. The small-gain theorem is known to be a stability condition for multi-input multi-output feedback systems. Additionally, a novel control structure for the bilateral control system with communication delay is proposed. The bilateral control system with the proposed structure satisfies the L2-stability condition of the small-gain theorem. The experimental results show the utility of the proposed control structure.

Consensus problem is investigated for heterogeneous multi-agent systems composed of first-order agents and second-order agents in this paper. Leader-following consensus protocol is adopted to solve consensus problem of heterogeneous multi-agent systems with time-varying communication and input delays. By constructing Lyapunov-Krasovkii functional, sufficient consensus conditions in linear matrix inequality (LMI) form are obtained for the system under fixed interconnection topology. Moreover, consensus conditions are also obtained for the heterogeneous systems under switching topologies with time delays. Simulation examples are given to illustrate effectiveness of the results.

This paper studies the containment control issue of multi-agent systems with time delay. By adopting continuous-time and sampled-data-based control protocols, we establish some necessary and sufficient containment control criteria for multi-agent systems with time delay. For the continuous-time case, our results show that both topology structure and time delay play an important role in the containment control of multi-agent systems, no matter whether the leaders are stationary (first-order system) or dynamic with constant velocity and time-varying position (second-order system). Furthermore, the maximum value of time delay to guarantee the achievement of containment control is given by the Hopf bifurcation theory. Moreover, we extend the results to the sampled-data case. Finally, numerical simulations are given to illustrate our main results.

Many marine missions demand a single remotely operated underwater vehicle (ROV) or multiple ROVs to achieve position tracking. However, the time-varying communication delay in water makes it challenging to achieve the tracking task. This paper is concerned with single-vehicle tracking and multi-vehicle tracking problems. With the consideration of time-varying communication delay, two model-free proportional-derivative (PD) tracking controllers are designed. For the proposed controllers, Lyapunov–Krasovskii functions are constructed to analyze the stability, and then sufficient conditions for asymptotic stability are presented. In particular, the relationship between controller gains and time delay is established by using linear matrix inequality (LMI), such that the allowable upper bound of time delay can be calculated. Finally, simulation and experiment results are performed to validate the effectiveness.

Sampled-data based containment control of continuous-time multi-agent systems with switching topology and time-delays

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.