Network delay compensation method between transmitter node and (control) actuator node

Abstract

The invention provides a network delay compensation method between a transmitter node and a (control) actuator node, and belongs to the technical field of network control systems. In the method, an actual network data transmission process between the transmitter node and the (control) actuator node is used for substituting a network delay compensation model of the process, so that measurement and estimation or identification of network data transmission delay between nodes and requirements on node clock signal synchronization are eliminated. By the method, the influence of delay on stability of a time system can be reduced and the control performance quality of the system can be improved. The method is suitable for delay dynamic compensation and control of a network control system in which a controlled object mathematic model is known, the network only exists between the transmitter node and the (control) actuator node and a certain number of data packets are lost in the network.

Description

technical field [0001] The invention relates to a network control system delay compensation method in which the network only exists between the transmitter node and the (control) actuator node, and belongs to the interdisciplinary field of network communication, computer technology and automatic control. Background technique [0002] A closed-loop feedback control system based on a real-time communication network is called a networked control system (Networked control systems, NCS), and a typical structural block diagram of a networked control system suitable for the present invention is as follows figure 1 shown. [0003] NCS can realize complex large-scale system and remote network control, realize network resource sharing, increase system flexibility and reliability, and also make system analysis and design extremely complicated. Due to limited network bandwidth and shared by each node of the system, When the transmitter node and the (control) actuator node exchange data...

AI Technical Summary

Problems solved by technology

[0008] Since there is an exponential term e of the network delay τ in the denominator of the closed-loop transfer function shown in equation (1) -τs , the existence of time delay will deteriorate the control performance quality of the system, and even cause the system to lose stability, and in severe cases, the system may fail.

[0009] The key to reducing the impact of delay on system stability is whether the exponential term e of the network delay τ between the transmitter node and the (control) actuator node can be realized -τs It is removed from the denominator of equation (1), that is, the exponential term of the network delay is not included in the closed-loop characteristic equation, and then the compensation for the network delay is realized. However, to realize the compensation for the network delay, we must first know The size of the network delay. At present, the method usually used at home and abroad is to compensate the influence of the delay on the system stability by measuring the network delay τ. However, because the accurate measurement of the network delay needs to satisfy the node clock signal Synchronization requirements. If hardware is used to realize the complete synchronization of node clock signals, a large economic investment is required; if software is used to correct clock signals, it is difficult to achieve because the correction signals may be affected by network delays when they are transmitted between nodes. The node clocks are completely synchronized; if the method of estimating, identifying or predicting the network delay is used to obtain the size of the network delay, the accurate probability distribution of the network delay must be known, or an accurate mathematical model, but due to the network delay The size may be random or time-varying, and its value is related to factors such as the specific network protocol, network load, and network topology, and there may be errors in the estimation or identification of network delay.

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