A robust quantized consensus protocol for discrete-time multi-agent systems with additive noise

An event-triggered consensus protocol for quantized second-order multi-agent systems with network delay and process noise

This paper focuses on the quantized consensus problem of discrete-time second-order multi-agent systems which suffer from bounded process noise. In such systems, neighboring agents exchange information through a digital network that has only a finite bit rate and is subject to bounded network delay. Network delay may exacerbate the effects of quantization error and degrade the control performance by reducing the information to be extracted from receiving time instants of exchange packets. To handle network delay and save communication bit rates, an event-triggered distributed control protocol based on a dynamic encoding-decoding policy is proposed. Under the proposed event-triggered protocol, the asymptotic consensus of the concerned noise-free multi-agent systems can be achieved at a lower bit rate than that of periodic sampling control. This bit rate superiority results from the fact that our protocol makes use of the extra information being extracted from the event-triggering time instants. Moreover, it is shown that no higher bit rate is required to guarantee the desired consensus in the existence of bounded process noise. Simulations are done to demonstrate the effectiveness of our consensus protocol. As shown by our numerical examples, the occupied bit rate to ensure the desired consensus can be saved by up to 50% compared with periodic sampling strategies.

Consensus of Fractional-Order Double-Integral Multi-Agent System in a Bounded Fluctuating Potential

At present, the consensus problem of fractional complex systems has received more attention. However, there is little literature on the consensus problem of fractional-order complex systems under noise disturbance. In this paper, we present a fractional-order double-integral multi-agent system affected by a common bounded fluctuating potential, where the protocol term consists of both the relative position and velocity information of neighboring agents. The consensus conditions of the presented system in the absence of noise are analytically given and verified by a numerical simulation algorithm. Then, the influences of the system order and other system parameters on the consensus of the presented system in the presence of bounded noise are also analyzed. It is found that when compared with the classical integer-order system, the presented fractional-order system has a larger range of consensus parameters and has more rich dynamic characteristics under the action of random noise. Especially, the bounded noise has a promoting effect on the consensus of the presented fractional-order system, while there is no similar phenomenon in the corresponding integer-order system.

Bit-Rate Conditions for the Consensus of Quantized Multiagent Systems Based on Event Triggering

This article investigates the asymptotic consensus problem for multiple discrete-time agents with general dynamics under event-triggered sampling. In such multiagent systems (MASs), the information exchanged between neighboring agents is quantized and transmitted through a digital communication network. Due to the limited bandwidth, it is impossible for agents to capture the precise states of neighbors and only their quantized version can be received, which may degrade or even break the consensus of these MASs. In order to ensure the desired consensus and save the occupied network bandwidth, a model-based event-triggering strategy is well co-designed with a dynamic quantization method. Under the proposed strategy, the error between the real state and its estimated version at neighbors is always bounded by an event-triggering function, which is also taken to compute an upper bound on the control inputs of all agents. We derive a sufficient bit-rate condition required for the desired asymptotic consensus. That condition is mainly determined by the dynamics and communication network topology of agents. Since our event-triggering strategy takes advantage of the extra information extracted from the event-triggering time instants of all feedback packets, the derived bit rate can be lower than that of the conventional periodic sampling strategies, while still ensuring the consensus of the concerned MAS. Simulations are done to illustrate the advantages of the derived bit-rate condition.

Analysis on Distributed Output Regulator of Discrete Multi-agent System Combined with Fuzzy Identification Method

This paper combines the traditional output regulation (OR) theory with fuzzy identification method, and designs a distributed output regulator for the multi-agent system (MAS). In view of the situation that the follower model in the MAS cannot be obtained accurately, the fuzzy model is established to make it approximate to the considered nonlinear discrete follower agent system first. By employing fuzzy identification method and OR theory, a distributed controller is proposed, make follower agents track the reference signal given by the dynamic leader. Two numerical examples demonstrate the obtained results.

Bit-Rate Conditions for the Consensus of Quantized Multiagent Systems With Network-Induced Delays Based on Event Triggering

This paper is mainly concerned with bit-rate conditions to guarantee the consensus of unstable scalar multiagent systems by event-triggering strategies. In such systems, state information is quantized and transmitted among agents through digital communication networks which suffer from network-induced delays. In order to save communication resources, we implement a periodic event-triggering scheme, under which agents quantize and transmit their own states when a predefined event is triggered. By introducing a well-designed internal saturation function, the proposed strategy can place a priori bounds on the control inputs of agents and guarantee the asymptotic consensus of agents at a finite bit rate, even under network-induced delays. By extracting extra information from the receive time instants of data packets, our strategy can require less information carried by data packets and a lower bit rate to maintain the desired asymptotic consensus than some state-of-the-art time-triggered consensus strategies. Under our strategy, the obtained bit-rate conditions depend on the network-induced delays, the unstable eigenvalue of agent dynamics, and the network topology. The simulation results are provided to illustrate the effectiveness of these bit-rate conditions.

Some necessary and sufficient conditions for containment of second-order multi-agent systems with intermittent sampled data

This paper comes up with two novel sampled data containment control protocols with intermittent communication for second-order multi-agent systems, where the intermittent communication is periodic. For the protocols with or without time delay, two necessary and sufficient conditions are obtained. In both cases, containment control can be implemented, where each follower can eventually reach the convex hull made up of multiple leaders. In particular, for the protocol with time delay, depending on the size of the time delay, two different conditions are obtained to achieve containment. More interestingly, the result that the smaller the time delay is, the easier it is to calculate the interval of the appropriate sampling period has been found. At last, the correctness of the theoretical results is verified by several simulations.

H∞ consensus of Markovian jump multi-agent systems under multi-channel transmission via output feedback control strategy

This paper studies the H_∞ consensus problem of discrete-time multi-agent systems with Markovian jump parameters and exogenous disturbances via static output feedback control strategy. Each agent's measurement information is transmitted to its neighbors through the multiple quantized channels in which each channel obtains transmission permission based on a Markovian jump dispatcher. A static output feedback consensus controller is employed. In terms of an appropriate Lyapunov function, some sufficient conditions are derived to assure stochastic consensus for multi-agent systems subject to a specified H_∞ performance. At length, a simulation example is provided to illustrate the correctness of the result.