Abstract:

Aiming at the fair and efficient bandwidths allocation for the geographically distributed control systems, a distributed and dynamic bandwidth allocation algorithm was proposed.Firstly, the bandwidth allocation problem was formulated as a convex optimization problem, namely, the sum of utilities of all the control systems was maximized. Further, the idea of the distributed bandwidth allocation algorithm was adopted to make the control systems vary their sampling periods based on fed-back congestion information from the network, and get the maximum sampling rate or maximum transmission rate which could be used. Then the interaction between control systems and links was modelled as a time-delay dynamical system, and Proportional-Integral (PI) controller was used as the link queue controller to realize the algorithm; The simulation results show that the proposed bandwidth allocation algorithm can not only make the transmission rates of all plants converge to the value where all plants share the bandwidth equally in 10 seconds. At the same time, for the PI controller, its queue stabilizes around the desired set point of 50 packets, and can accurately and steadily track the input signal to maximize the performance of all control systems.

Key words: utility function, bandwidth allocation, distributed control system, closed loop

摘要：

针对公平、有效分配地理上呈分布式的控制系统带宽的问题,提出了一种分布式的动态带宽分配算法。首先把这种带宽分配问题构建为一个凸优化问题,使全部控制系统的效用最大化;再采用分布式带宽分配算法思想,使得控制系统基于网络反馈的拥塞信息改变其采样周期,得到可利用的最大采样速率或最大传输速率;然后把控制系统和链路之间的相互作用建模为一个时延动态系统,并采用比例积分(PI)控制器作为链路队列控制器来实现算法。仿真结果表明,所提带宽分配算法不仅能够使全部设备的传输速率在10 s内收敛到全部设备均等共享的链路带宽值;同时对于PI控制器来说,其队列稳定在期望设置点50个数据包左右,而且能够准确、稳定地跟踪输入信号,使全部控制系统的性能最大化。

关键词: 效用函数, 带宽分配, 分布式控制系统, 闭环回路