This article considers the consensus of second-order multiagent systems (MASs) under a directed communication topology. By introducing time-varying gains into observers, two types of novel continuous-discrete-time observers are presented to estimate state information of agents under two sampling mechanisms, respectively, namely: 1) a synchronous nonuniform sampling (SNS) mechanism and 2) an asynchronous nonuniform sampling (ANS) mechanism. A new design method of the time-varying gain observer is proposed, in that it can allow for one to select a consensus protocol with lower cost observers to attain the consensus task. Only sampled position information needs to be transmitted in designing consensus protocols for the MSAs, and neither velocity information nor control input information is required. Under the SNS mechanism, a consensus condition is obtained and it is shown that the introduction of time-varying gains in the observers indeed can improve their convergence. Under the ANS mechanism, the corresponding consensus protocol allows the sampling and transmission of different agents to be asynchronous and aperiodic, which means that each agent may sample and transmit its information in line with its own sampling requirements. Furthermore, each sampling period can be arbitrarily selected within a certain range while ensuring the consensus of the MASs. Finally, numerical examples are given to illustrate the effectiveness of the obtained results.

>Dear editor,With the rapid development of communication,control, and computer technologies, networked control systems (NCSs) have been widely used in various fields owing to its advantages of sharing information resources, reducing system wiring,and increasing the flexibility and reliability of systems [1–3]. In NCSs, sampling-data systems com-

In this paper, a multi-sensor multi-rate (MSMR) sampling mechanism is introduced in multi-agent systems (MASs), and the output consensus problem for heterogeneous MASs with the MSMR sampling mechanism is investigated. By constructing a dynamic compensator for each agent, a new distributed control strategy that does not depend on the eigenvalue information of the Laplacian matrix is proposed. Under the proposed control strategy, the output consensus problem of heterogeneous MASs can be solved by Lyapunov stability method. Moreover, each agent’s controller design does not need continuous information of its neighbors. The proposed method in this paper is also used to deal with the state consensus problem and output consensus problem of homogeneous MASs with the MSMR sampling mechanism, respectively. Finally, two numerical simulation examples are given to illustrate the effectiveness of our results and the advantages of the MSMR sampling mechanism in improving the control performance of the MASs.