Formation control of non-identical multi-agent systems

IEEE Transactions on Automatic Control, 2000

We consider the problem of distributed formation control of a large number of vehicles. An individual vehicle in the formation is assumed to be a fully actuated point mass. A distributed control law is examined: the control action on an individual vehicle depends on (i) its own velocity and (ii) the relative position measurements with a small subset of vehicles (neighbors) in the formation. The neighbors are defined according to an information graph.

This paper addresses distributed time-varying output formation (TVOF) control problems using an adaptive output-feedback approach for general linear multi-agent systems with directed communication topology. Compared with the previous work on formation control, the multi-agent system can achieve a predefined TVOF via output feedback without using the global information about the directed communication topology. Firstly, an adaptive output formation controller is constructed via dynamic output feedback information and sequential observers. Through the output formation decomposition and observability decomposition, the distributed TVOF control problems are transformed into stabilization problems. Then, a distributed algorithm is proposed to determine the parameters in the adaptive output formation controller independent of the global information of the directed communication topology. A feasible TVOF set is given. Moreover, the stability of the proposed algorithm is proved based on the Lyapunov theory. Finally, simulation examples are presented to demonstrate the effectiveness of the obtained results.

International Journal of Systems Science, 2009

This article investigates a formation control problem of mobile robots. Two main issues of the formation control problem are addressed; one is the implementation of distributed formation control and another is the analysis of effect of network communication on the closed-loop systems. The distributed formation control is obtained by modelling the formation control problem as a linear-quadratic Nash differential game through the use of graph theory. The obtained distributed controller is a state feedback controller that requires both local state and neighbour robot states. As the neighbour robot states are obtained via networks, the network performance affects the control system. Network-induced delay is considered in this article. The stability analysis of the proposed distributed formation controller under network-induced delay is given. A compensation scheme for network-induced delay is proposed and analysed. Mobile robots with double integrator dynamics are used in the formation control simulation. Simulation results are provided to justify the models and solutions.

IEEE Transactions on Control of Network Systems, 2019

This paper proposes a fully distributed control protocol that achieves time-varying group formation tracking for linear multiagent systems connected via a directed graph. The group formation tracking often leads to sub-formations especially when the leaders are placed far apart or they have separate control inputs. In the proposed approach, the followers are distributed into several subgroups and each subgroup attains the predefined subformation along with encompassing the leaders. Each subgroup can be assigned multiple leaders, contrary to the single-leader case considered in most existing literature, which makes the current problem nontrivial. When multiple leaders exist in a subgroup, the subformation attained by that subgroup keeps tracking a convex combination of the states of the leaders. A distributed adaptive control protocol has been introduced in this paper which uses only relative state information and, thus, avoids direct computation of the graph Laplacian matrix. Due to the virtue of this, the proposed scheme remains effective even when some of the agents get disconnected from the network due to sudden communication failure. An algorithm is provided to outline the steps to design the control law to attain time-varying group formation tracking with multiple leaders. Toward the end, a case study on multitarget surveillance operation is taken up to show an important application of the proposed adaptive control technique.

AIAA Guidance, Navigation, and Control Conference, 2012

Formation control of network of multi-agent systems with heterogeneous nonlinear dynamics is formulated as an optimal tracking problem and a decentralized controller is developed using the framework of 'adaptive critics' to solve the optimal control problem. The reference signal is assumed available only in online implementation so its dynamics is unavailable for offline training of the neurocontroller. However, this issue is resolved by using a re-optimization of the network output through retraining of the neurocontroller online. Finally, the developed controller is applied to the formation control of multispacecraft orbiting the Earth at different orbits and seeking consensus on their position to dock.

This paper considers the formation tracking control problem of large-scaled Multi-Agent Systems (MAS) for which the model is based on a system of mutually independent wave Partial Differential Equations (PDEs). The spatial derivatives in the equation correspond to the underlying communication topology of the agents. A leader-follower mode is employed in the control algorithm, with which the agents on the boundary of PDEs are chosen as leaders knowing the tracking trajectory and all the other agents are followers. Each follower has only the information of its own relative position and velocity to its topological neighbors. With a designed distributed controller, the formation tracking error is bounded by a constant proportional to the acceleration of the desired trajectory. Robustness of the control law to a perturbation in the velocity measurement is also discussed. Furthermore, some simulation studies are provided to show the effectiveness of the control algorithm.

This paper investigates the formation control problem for nonlinear multi-agent systems with a virtual leader. A distributed formation control strategy based on linear extended state observer (LESO) is proposed under the hypothesis that velocity of the agent's neighbors could not be measured. Some sufficient conditions are established to ensure that the nonlinear multi-agent systems form a predefined formation with switching topology when the nonlinear function is known. Moreover, the tracking errors are bounded with external disturbance. Lastly, a numerical example with different scenarios is presented to demonstrate the validity of the obtained results. Citation: Wen Qin, Zhongxin Liu, Zengqiang Chen. Formation control for nonlinear multi-agent systems with linear extended state observer. IEEE/CAA Journal of Automatica Sinica, 2014, 1(2): 171-179

2008 American Control Conference, 2008

We study the distributed control of autonomous second order agents under persistent disturbances. We show that the usual averaging rule for convergence to formation is only able to reject constant disturbances that are identical for each agent. We also prove that using a distributed dynamic compensation law the system can be made to converge to formation under constant perturbations of the control input even when the perturbations are different for each agent. We illustrate the results with numerical simulations.

2015

In this paper, we used algebraic connectivity in a network to speed up formation in multi-agent autonomous systems. Formation topology of a multi-agent system with single integrator agent dynamics represented as a graph problem. Algebraic connectivity of the graph is expressed as an optimization problem where the objective is to maximizing it through the graph Laplacian. The problem is solved for some formation examples. Simulation is verified that the multi-agent system with maximized algebraic connectivity network structure (optimized Laplacian structure) has more convergence speed in reaching to the given formations.

arXiv (Cornell University), 2019

This paper presents a novel control protocol for robust distance-based formation control with prescribed performance in which agents are subjected to unknown external disturbances. Connectivity maintenance and collision avoidance among neighboring agents are also handled by the appropriate design of certain performance bounds that constrain the inter-agent distance errors. As an extension to the proposed scheme, distance-based formation centroid maneuvering is also studied for disturbance-free agents, in which the formation centroid tracks a desired time-varying velocity. The proposed control laws are decentralized, in the sense that each agent employs local relative information regarding its neighbors to calculate its control signal. Therefore, the control scheme is implementable on the agents' local coordinate frames. Using rigid graph theory, input-to-state stability, and Lyapunov based analysis, the results are established for minimally and infinitesimally rigid formations in 2-D or 3-D space. Furthermore, it is argued that the proposed approach increases formation robustness against shape distortions and can prevent formation convergence to incorrect shapes, which is likely to happen in conventional distance-based formation control methods. Finally, extensive simulation studies clarify and verify the proposed approach.