Haibo Min

Decentralized adaptive attitude synchronization of spacecraft formation

Abstract This paper studies adaptive attitude synchronization of spacecraft formation with possible time delay. By introducing a novel adaptive control architecture, decentralized controllers are developed, which allow for parameter uncertainties and unknown external disturbances. Based upon graph theory, Lyapunov stability theory and time-delay control theory, analytical tools are also provided. A distinctive feature of this work is to address the adaptive attitude synchronization with unknown parameters and coupling time delay in a unified theoretical framework, with general directed information flow. It is shown that arbitrary desired attitude tracking and synchronization with respect to a given reference can be attained. Simulation results are provided to demonstrate the effectiveness of the obtained results.

Distributed consensus of a class of networked heterogeneous multi-agent systems

Abstract In this paper, we consider the consensus problem of a class of heterogeneous multi-agent systems composed of the linear first-order and second-order integrator agents together with the nonlinear Euler–Lagrange (EL) agents. First, we propose a distributed consensus protocol under the assumption that the parameters of heterogeneous system are exactly known. Sufficient conditions for consensus are presented and the consensus protocol accounting for actuator saturation is developed. Then, by combining adaptive controller and PD controller together, we design a protocol for the heterogeneous system with unknown parameters (in the nonlinear EL dynamics). Based on graph theory, Lyapunov theory and Barbalats Lemma, the stability of the controllers is proved. Simulation results are also provided to illustrate the effectiveness of the obtained results.

Distributed Adaptive Consensus for Multiple Mechanical Systems with Switching Topologies and Time-varying Delay

Abstract This paper studies the adaptive consensus problem of networked mechanical systems with time-varying delay and jointly-connected topologies. Two different consensus protocols are proposed. First, we present an adaptive consensus protocol for the connected switching topologies. Based on graph theory, Lyapunov stability theory and switching control theory, the stability of the proposed algorithm is demonstrated. Then we investigate the problem under the more general jointly-connected topologies, and with concurrent time-varying communication delay. The proposed consensus protocol consists of two parts: one is for the connected agents which contains the current states disagreement among them and the other is designed for the isolated agents which contains the states difference between the current and past. A distinctive feature of this work is to address the consensus control problem of mechanical systems with unknown parameters, time-varying delay and switching topologies in a unified theoretical framework. Numerical simulation is provided to demonstrate the effectiveness of the obtained results.

Consensus of Nonlinear Multi-agent Systems with Self and Communication Time Delays: A Unified Framework

Abstract In this paper, we study the consensus problem of multi-agent systems with parametric uncertainties on directed graph communication topologies containing a spanning tree. The challenge lies in that the input–output property of a strictly proper system transfer function involving self and communication delays and the extremum of a delay-involved transfer function are both unclear. By establishing a new input–output property of the delay-involved strictly proper transfer function and applying a constructive approach in frequency domain, we obtain the extremum of the delay-involved transfer function, upon which, we establish a unified framework to resolve the consensus problem of multi-agent systems with parametric uncertainties and time delays, and the terminal convergence point value is achieved. Based upon Lyapunov stability theory and frequency domain input–output analysis, we demonstrate that the proposed unified consensus control framework ensures scaled weighted average consensus with the integral action of the synchronization signal vector. Simulation results are provided to demonstrate the effectiveness of the proposed consensus scheme.

Coordination Control of Networked Euler-Lagrange Systems with Possible Switching Topology

Abstract This paper studies adaptive coordination control of Euler-Lagrange (EL) systems with unknown parameters in system dynamics and possible switching topology. By introducing a novel adaptive control architecture, decentralized controllers are developed, which allow for parametric uncertainties. Based upon graph theory, Lyapunov theory and switching control theory, the stability of the proposed algorithms are demonstrated. A distinctive feature of this work is to address the coordination control of EL systems with unknown parameters and switching topology in a unified theoretical framework. It is shown that both static and dynamic coordinations can be reached even when the communication is switching. Simulation results are provided to demonstrate the effectiveness of the obtained results.

Distributed finite-time attitude containment control of multi-rigid-body systems

Abstract In this paper, we study the distributed finite-time attitude containment control problem for multi-rigid-body systems with multiple stationary and dynamic leaders under directed graphs. Based upon two sliding mode observation vectors, the input torque is designed to achieve the control goal. In the regulation case, all the followers will converge into the attitude convex hull spanned by the leaders in finite time, while in the dynamic leaders case, not only the attitudes but also the attitude derivatives of the followers will converge into the convex hull of the leaders in finite time. Necessary and sufficient criteria are established for both the two protocols. Finally, all the theoretical results are illustrated by numerical simulations.

Consensus for multiple heterogeneous Euler–Lagrange systems with time-delay and jointly connected topologies

Abstract In this paper, we consider the consensus problem of multiple agents modeled by Euler–Lagrange (EL) equation, among which two classes of agents are addressed, i.e., some agents with exactly known parameters and the others with parametric uncertainties. We propose a distributed consensus protocol for the heterogeneous EL systems in which both time-delay and jointly connected topologies are taken into consideration. Based on graph theory, Lyapunov theory and Barbalat׳s lemma, the stability of the controller is proved. A distinctive feature of this work is to investigate the consensus problem of EL systems with heterogeneous dynamics, time-delay and jointly connected topologies in a unified theoretical framework. Simulation results are also provided to illustrate the effectiveness of the obtained results.

Distributed 6DOF coordination control of spacecraft formation with coupling time delay

This paper studies adaptive six Degree-of-Freedom (6DOF) coordination control of spacecraft formation with coupling time delay. By rearranging the combined translational and rotational dynamics into a unified Euler-Lagrange formulation, the developed controllers can be applied directly to maintain formation as well as desired relative attitudes. Then, based on a novel adaptive control architecture, distributed controllers are developed, which allow for parameter uncertainties and unknown external disturbances. It is shown that arbitrary desired formation and relative attitudes among spacecraft can be obtained with constant coupling time delays. Simulations are provided that demonstrate the effectiveness of our theoretical results.

Distributed containment control of networked nonlinear second-order systems with unknown parameters

In this paper, we study the containment control problem for nonlinear second-order systems with unknown parameters and multiple stationary U+002F dynamic leaders. The topologies that characterize the interaction among the leaders and the followers are directed graphs. Necessary and sufficient criteria which guarantee the control objectives are established for both stationary leaders U+0028 regulation case U+0029 and dynamic leaders U+0028 dynamic tracking case U+0029 based protocols. The final states of all the followers are exclusively determined by the initial values of the leaders and the topology structures. In the regulation case, all the followers converge into the convex hull spanned by the leaders, while in the dynamic tracking case, not only the positions of the followers converge into the convex hull but also the velocities of the followers converge into the velocity convex hull of the leaders. Finally, all the theoretical results are illustrated by numerical simulations.

An overview of research in distributed attitude coordination control

This paper provides an overview of attitude coordination problems of multi-rigid-body with the goal of promoting research in this area. Theoretical results regarding consensus seeking with different system models, different communication topologies, different control goals and different techniques are summarized. And applications of consensus protocols to multirigid-body coordination are investigated. Finally, some future research directions and open problems are also proposed.