时隙ALOHA协议下的网络化控制系统协同设计

Control communication co-design for networked control systems with slotted ALOHA protocol

针对网络化控制系统中信道容量有限的问题,本文提出一种基于时隙ALOHA通信协议的控制与通信协同设计方法.将控制系统的采样周期划分为若干等长度的时隙,在每个时隙中,系统的分布式传感器通过时隙ALOHA 协议来随机竞争接入网络.由于在不同的采样周期各个传感器的接入状态不同,整个状态反馈控制系统将在若干子系统之间进行切换.据此,本文建立了离散的切换系统模型,并利用分段李雅普诺夫函数方法和平均驻留时间技术得到了能够保证系统指数稳定的充分条件.然后,给出能够保证控制系统稳定所需的信道吞吐率的界限,进而得到了时隙ALOHA协议中的最大重传次数与控制系统衰减率的定量关系.通过上述方法,本文建立了控制-通信协同设计的框架结构,可将控制器的增益矩阵和时隙ALOHA通信协议进行协同设计.最后,通过仿真验证了本文所提出的协同设计方法的有效性.

Considering that the communication channel of networked control systems(NCSs)is capacity limited,this paper investigates a control-communication co-design problem by using the slotted ALOHA protocol.Each sampling time interval is divided into several time slots,in each of which the distributed sensors randomly contend to access the communication channel based on the slotted ALOHA protocol.As the access states of the sensors change in different sampling time periods,the closed-loop NCSs switch among subsystems that are modeled from the original NCSs.Accordingly,a discrete time switch system model is built in this paper,and sufficient conditions that can ensure the exponential stability of the NCS s are derived by applying the piecewise Lyapunov function method and the average dwell time approach.Then,the lower bound of the communication throughput to guarantee the exponential stability of the NCSs is provided.Moreover,the quantitative relation between the maximum number of retransmissions in the slotted ALOHA protocol and the attenuation rate of the NCSs is derived.Based on these results,a control-communication co-design method is proposed such that the control gain matrix and the slotted ALOHA protocol can be designed simultaneously.Finally,a numerical simulation example illustrates the effectiveness of the proposed co-design method.