Memory-augmented adaptive flocking control for multi-agent systems subject to uncertain external disturbances

This paper presents a novel flocking algorithm based on a memory-enhanced disturbance observer.To compensate for external disturbances,a filtered regressor for the double integrator model subject to external disturbances is designed to extract the disturbance information.With the filtered regressor method,the algorithm has the advantage of eliminating the need for acceleration information,thus reducing the sensor requirements in applications.Using the information obtained from the filtered regressor,a batch of stored data is used to design an adaptive disturbance observer,ensuring that the estimated values of the parameters of the disturbance system equation and the initial value converge to their actual values.The result is that the flocking algorithm can compensate for external disturbances and drive agents to achieve the desired collective behavior,including virtual leader tracking,inter-distance keeping,and collision avoidance.Numerical simulations verify the effectiveness of the algorithm proposed in the present study.     

Cluster consensus of second-order multi-agent systems via pinning control

This paper investigates the cluster consensus problem for second-order multi-agent systems by applying the pinning control method to a small collection of the agents.Consensus is attained independently for different agent clusters according to the community structure generated by the group partition of the underlying graph and sufficient conditions for both cluster and general consensus are obtained by using results from algebraic graph theory and the LaSalle Invariance Principle.Finally,some simple simulations are presented to illustrate the technique.     

State-dependent event-triggered control of multi-agent systems

Event-triggered control has been recent/y proposed as an effective strategy for the consensus of multi-agent systems. We present an improved distributed event-triggered control scheme that remedies a shortcoming of some previous event- triggered control schemes in the literature. This improved distributed event-triggered method has no need for continuously monitoring each agent＇ neighbors. Moreover, each agent in the multi-agent systems will not exhibit the Zeno behavior. Numerical simulation results show the effectiveness of the proposed consensus control.     

Finite-time consensus of heterogeneous multi-agent systems

We investigate the finite-time consensus problem for heterogeneous multi-agent systems composed of first-order and second-order agents.A novel continuous nonlinear distributed consensus protocol is constructed,and finite-time consensus criteria are obtained for the heterogeneous multi-agent systems.Compared with the existing results,the stationary and kinetic consensuses of the heterogeneous multi-agent systems can be achieved in a finite time respectively.Moreover,the leader can be a first-order or a second-order integrator agent.Finally,some simulation examples are employed to verify the efficiency of the theoretical results.     

Distributed event-triggered consensus tracking of second-order multi-agent systems with a virtual leader

This paper investigates the consensus tracking problems of second-order multi-agent systems with a virtual leader via event-triggered control. A novel distributed event-triggered transmission scheme is proposed, which is intermittently examined at constant sampling instants. Only partial neighbor information and local measurements are required for event detection. Then the corresponding event-triggered consensus tracking protocol is presented to guarantee second-order multi-agent systems to achieve consensus tracking. Numerical simulations are given to illustrate the effectiveness of the proposed strategy.     

Reference model based consensus control of second-order multi-agent systems

This paper deals with the consensus problem of multi-agent systems with second-order dynamics.The objective is to design algorithms such that all agents will have same positions and velocities.First,a reference model based consensus algorithm is proposed.It is proved that the consensus can be achieved if the communication graph has a spanning tree.Different from most of the consensus algorithms proposed in the literature,the parameters of the control laws are different among agents.Therefore,each agent can design its control law independently.Secondly,it gives a consensus algorithm for the case that the velocities of the agents are not available.Thirdly,the effectiveness of the input delay and the communication delay is considered.It shows that consensus can be achieved if the input delay of every agent is smaller than a bound related to parameters in its control law.Finally,some numerical examples are given to illustrate the proposed results.     

Quad-rotor unmanned helicopter control via novel robust terminal sliding mode controller and under-actuated system sliding mode controller

This paper uses the recently developed novel robust terminal sliding mode control (NRTSMC) and under-actuated system sliding mode control (USSMC) approaches to solve the strong coupling and under-actuated problems of a small quad-rotor unmanned helicopter (QRUH). The two controllers have been widely adopted to act as a single control algorithm in many fields, respectively. However, this paper just displays the useful composite application of the two controllers. The QRUH model can be divided into two subsystems, including a fully actuated subsystem (FAS) and an under-actuated subsystem (UAS). For the FAS, the NRTSMC is used to solve the strong coupling problem, it can guarantee the FAS states converge to the desired equilibrium in a very short time, then the states are treated as time invariants and the UAS gets simplified. For the UAS, the USSMC is utilized to solve the under-actuated problem. The obtained simulation results show the applicability of the composite control when faced with external disturbances.     

Integral sliding mode control for a class of nonlinear neutral systems with time-varying delays

This paper focuses on sliding mode control problems for a class of nonlinear neutral systems with time-varying delays. An integral sliding surface is firstly constructed. Then it finds a useful criteria to guarantee the global stability for the nonlinear neutral systems with time-varying delays in the specified switching surface, whose condition is formulated as linear matrix inequality. The synthesized sliding mode controller guarantees the reachability of the specified sliding surface. Finally, a numerical simulation validates the effectiveness and feas.ibility of the proposed technique.     

Rotating consensus of multi-agent systems without relative velocity measurement

We study the rotating consensus of multi-agent systems without the relative velocity measurement in this paper. A new protocol is proposed. Then we use the theory of the complex system combined with the function continuity to derive a condition, under which all agents finally reach the rotating consensus. Finally, a numerical example is provided to illustrate our theoretical results.     

Agreement coordination for second-order multi-agent systems with disturbances

This paper is devoted to the study of consensus problems for the second-order multi-agent systems with external disturbances, switching topology and communication time-delay. Firstly, we perform a model transformation and separate the agreement states from the disagreement states. Secondly, according to this system, we derive a sufficient condition for consensus problem without disturbances by using the Lyapunov-based approach. Furthermore, we give a design criterion in terms of bilinear matrix inequality for the control protocol in the presence of disturbances. Finally, numerical simulations are provided to show the effectiveness of our strategies.     

一种分数阶混沌系统同步的自适应滑模控制器设计

针对分数阶混沌系统的同步问题, 基于滑模控制理论和自适应控制理论, 设计了一个具有较强鲁棒性的分数阶积分滑模面, 并提出了一种自适应滑模控制器在不消除非线性项的情况下实现一类三维分数阶混沌系统同步的方法. 利用所设计的自适应滑膜控制器实现了分数阶Chen系统、分数阶Liu系统以及分数阶Arneodo系统的混沌同步. 数值模拟仿真结果验证了所设计的控制器的有效性和可行性.     

Consensus for second-order multi-agent systems with position sampled data

In this paper, the consensus problem with position sampled data for second-order multi-agent systems is investigated.The interaction topology among the agents is depicted by a directed graph. The full-order and reduced-order observers with position sampled data are proposed, by which two kinds of sampled data-based consensus protocols are constructed. With the provided sampled protocols, the consensus convergence analysis of a continuous-time multi-agent system is equivalently transformed into that of a discrete-time system. Then, by using matrix theory and a sampled control analysis method, some sufficient and necessary consensus conditions based on the coupling parameters, spectrum of the Laplacian matrix and sampling period are obtained. While the sampling period tends to zero, our established necessary and sufficient conditions are degenerated to the continuous-time protocol case, which are consistent with the existing result for the continuous-time case. Finally, the effectiveness of our established results is illustrated by a simple simulation example.     

Stochastic bounded consensus tracking of leader-follower multi-agent systems with measurement noises and sampled-data

<正>This paper is concerned with the stochastic bounded consensus tracking problems of leader-follower multi-agent systems,where the control input of an agent can only use the information measured at the sampling instants from its neighbours or the virtual leader with a time-varying reference state,and the measurements are corrupted by random noises.The probability limit theory and the algebra graph theory are employed to derive the necessary and sufficient conditions guaranteeing the mean square bounded consensus tracking.It is shown that the maximum allowable upper boundary of the sampling period simultaneously depends on the constant feedback gains and the network topology. Furthermore,the effects of the sampling period on the tracking performance are analysed.It turns out that from the view point of the sampling period,there is a trade-off between the tracking speed and the static tracking error. Simulations are provided to demonstrate the effectiveness of the theoretical results.     

Bounded consensus tracking of second-order multi-agent systems with sampling delay under directed networks

The bounded consensus tracking problems of second-order multi-agent systems under directed networks with sam- pling delay are addressed in this paper. When the sampling delay is more than a sampling period, new protocols based on sampled-data control are proposed so that each agent can track the time-varying reference state of the virtual leader. By using the delay decomposition approach, the augmented matrix method, and the frequency domain analysis, necessary and sufficient conditions are obtained, which guarantee that the bounded consensus tracking is realized. Furthermore, some numerical simulations are presented to demonstrate the effectiveness of the theoretical results.     

Asymptotic bounded consensus tracking of double-integrator multi-agent systems with bounded-jerk target based on sampled-data without velocity measurements

This paper investigates asymptotic bounded consensus tracking(ABCT) of double-integrator multi-agent systems(MASs) with an asymptotically-unbounded-acceleration and bounded-jerk target(AUABJT) available to partial agents based on sampled-data without velocity measurements. A sampled-data consensus tracking protocol(CTP) without velocity measurements is proposed to guarantee that double-integrator MASs track an AUABJT available to only partial agents.The eigenvalue analysis method together with the augmented matrix method is used to obtain the necessary and sufficient conditions for ABCT. A numerical example is provided to illustrate the effectiveness of theoretical results.     

一种新颖的滑模非线性比例积分混沌控制方法

一种新颖的滑模非线性比例积分控制方法（SMNPIC）被提出用于高精度驱动一类时变不确定混沌系统到任意期望轨道。SMNPIC区别于以前的滑模控制技术之处在于滑动模的一个非线性比例积分函数被包含在控制率中，因此不仅稳态误差和高频抖振都被减小，同时鲁棒性和快速性也能被保证。此外，SMNPIC实际上能被作为一类非线性PID控制器，不仅仅跟踪误差及其直到n-1阶微分被考虑，而且跟踪误差的积分也被考虑，因此有比传统PID更多的有用信息能被使用，因此更好的动静态特性能被获得。通过不确定Duffing-Holmes系统的仿真实例证实了SMNPIC用于混沌控制能获得好的性能。     

基于滑模控制的分数阶混沌系统的自适应同步

基于滑模控制理论和自适应控制理论,研究了分数阶混沌系统的同步问题.设计了新的分数阶积分滑模面,并提出了用单一自适应控制器实现一类三维分数阶混沌系统同步的方法.数值模拟证实了所提方法的有效性. 关键词： 滑模控制 分数阶混沌系统 单一控制器 自适应同步     

基于自适应滑模控制的不同维分数阶混沌系统的同步

针对异结构不同维分数阶混沌系统的广义同步问题进行研究, 设计了一种将滑模变结构理论和自适应控制理论相结合的方法.通过设计一种对外界干扰具有强鲁棒性的分数阶滑模面, 以及构造合适的自适应滑模控制器, 该控制器将系统的运动控制到滑模面上, 使系统轨道沿滑动模运动到所需的控制状态, 最终实现了两个不同维异结构混沌系统之间的广义同步.以四维超混沌Chen系统和三维Chen混沌系统为例, 对这两个系统分别进行升维和降维的同步仿真. 仿真模拟结果表明, 运用本文设计的控制器, 经过短暂的时间, 两系统的广义误差变量始终平稳地趋于零, 即证明了这种控制器的有效性. 关键词： 分数阶混沌系统 异结构 自适应滑模控制 混沌同步     

Leader-following consensus criteria for multi-agent systems with time-varying delays and switching interconnection topologies

We consider multi-agent systems with time-varying delays and switching interconnection topologies.By constructing a suitable Lyapunov-Krasovskii functional and using the reciprocally convex approach,new delay-dependent consensus criteria for the systems are established in terms of linear matrix inequalities(LMIs),which can be easily solved by using various effective optimization algorithms.Two numerical examples are given to illustrate the effectiveness of the proposed methods.     

Fault-tolerant finite-time dynamical consensus of double-integrator multi-agent systems with partial agents subject to synchronous self-sensing function failure

This paper investigates fault-tolerant finite-time dynamical consensus problems of double-integrator multi-agent systems (MASs) with partial agents subject to synchronous self-sensing function failure (SSFF). A strategy of recovering the connectivity of network topology among normal agents based on multi-hop communication and a fault-tolerant finite-time dynamical consensus protocol with time-varying gains are proposed to resist synchronous SSFF. It is proved that double-integrator MASs with partial agents subject to synchronous SSFF using the proposed strategy of network topology connectivity recovery and fault-tolerant finite-time dynamical consensus protocol with the proper time-varying gains can achieve finite-time dynamical consensus. Numerical simulations are given to illustrate the effectiveness of the theoretical results.