Time-varying formation tracking analysis and design problems for second-order Multi-Agent systems with switching interaction topologies are studied, where the states of the followers form a predefined time-varying formation while tracking the state of the leader. A formation tracking protocol is constructed based on the relative information of the neighboring agents. Necessary and sufficient conditions for Multi-Agent systems with switching interaction topologies to achieve time-varying formation tracking are proposed together with the formation tracking feasibility constraint based on the graph theory. An approach to design the formation tracking protocol is proposed by solving an algebraic Riccati equation, and the stability of the proposed approach is proved using the common Lyapunov stability theory. The obtained results are applied to solve the target enclosing problem of a multiquadrotor unmanned aerial vehicle (UAV) system consisting of one leader (target) quadrotor UAV and three follower quadrotor UAVs. A numerical simulation and an outdoor experiment are presented to demonstrate the effectiveness of the theoretical results.

Formation-containment control problems for multiple multirotor unmanned aerial vehicle (UAV) systems with directed topologies are studied, where the states of leaders form desired formation and the states of followers converge to the convex hull spanned by those of the leaders. First, formation-containment protocols are constructed based on the neighboring information of UAVs. Then, sufficient conditions for multi-UAV systems to achieve formation-containment are presented. An explicit expression to describe the relationship among the states of followers, the time-varying formation for the leaders and the formation reference is derived. It is shown that the states of followers not only converge to the convex hull formed by those of leaders but also keep certain formation specified by the convex combination of the formation for the leaders. Moreover, an approach to determine the gain matrices of the formation-containment protocol is proposed by solving an algebraic Riccati equation. Finally, a formation-containment platform with five quadrotor UAVs is introduced, and both the simulation and experimental results are presented to demonstrate the effectiveness of the obtained results.

This paper studies the time-varying output formation (TVOF) tracking problems for heterogeneous linear multi-agent systems with a nonautonomous leader on directed topologies, where the dynamics of the agents can be different in the aspects of both parameters and dimensions, and the leader can have unknown control input. A TVOF tracking protocol and a design algorithm are presented using the neighboring interaction. In the proposed protocol, a distributed observer with adaptive updating mechanism is constructed for each follower to asymptotically estimate the state of the leader under the influences of the leader's unknown input firstly. Then, a local formation controller is presented by utilizing the distributed observer, the local state observer and the desired formation vector. Based on the Lyapunov stability theory, it is proved that the expected TVOF tracking can be accomplished by the heterogeneous multi-agent systems in the presence of the leader's unknown input. Furthermore, a continuous TVOF tracking protocol with σ-modification adaptive law is proposed to avoid the large chattering phenomenon.

Time-varying formation tracking (TVFT) control problems for a team of unmanned aerial vehicles (UAVs) with switching and directed interaction topologies are investigated, where the follower UAVs realize a given time-varying formation while tracking the leader UAV. A TVFT control protocol is firstly constructed utilizing local neighboring information, where the information of the leader UAV is only available to partial followers and the neighborhood can be switching. An algorithm composed of four steps is provided to design the TVFT protocol. It is proved that the UAV swarm system can realize the TVFT using the designed protocol if the dwell time for the switching directed topologies is larger than a fixed threshold and the TVFT feasibility condition is satisfied. Based on the ultrawideband positioning technology, a quadrotor UAV formation control platform with four quadrotor UAVs is given. The obtained theoretical results are applied to solve the target enclosing problems of the UAV swarm systems. A flying experiment for three follower quadrotor UAVs to enclose a leader quadrotor UAV is carried out to verify the effectiveness of the presented results.

This article addresses the distributed secure platoon control of connected vehicles with denial-of-service (DoS) attack phenomena, which may occur at some sampling time instant. First, a switched time-delay system model is introduced, which captures the time-varying sampling and the DoS attack phenomena simultaneously. Then, sufficient conditions are obtained based on the Lyapunov stability theory, the Jensen’s Inequality method, and the topology matrix decoupling technique, such that the vehicle platoon system under consideration achieves an exponential tracking performance. In this article, the presented system design conditions establish several quantitative relationships between attack parameters and system performance. Moreover, the critical values of attack frequency (AF) and the sampling interval (SI) are also derived, respectively. Finally, both of the simulation and experiment studies on a network of four vehicles are introduced to validate the design.

The adaptive practical optimal time-varying formation tracking problems of the disturbed high-order multi-agent systems with a noncooperative leader are considered. Different from the former achievements, the effects of the leader’s unknown control input and followers’ external disturbances are both considered in the optimal time-varying formation tracking issues. Firstly, an adaptive practical optimal time-varying formation tracking protocol is proposed. The extended state observers and adaptive neural networks are introduced to estimate the integrated uncertainty and value function for the adaptive protocol, respectively. Then, an algorithm is presented to determine the control parameters for the adaptive optimal protocol and neural networks weights update laws. Thirdly, the stability and the optimal formation tracking property are analyzed for the closed loop disturbed high-order multi-agent system. Finally, the numerical simulation results are presented for revealing the effectiveness of the obtained theoretical methods.