Network delay compensation method between transducer (controller) node and actuator node

Abstract

The invention provides a network delay compensation method between a transducer (controller) node and an actuator node, which belongs to the technical field of network control systems. The method adopts the real network data transmission process between the transducer (controller) node and the actuator node to replace a network delay compensation mode between the two, thereby eliminating measurement, estimation, observation or identification of network data transmission delay between the nodes and eliminating the requirement on clock signal synchronization of the nodes. By adopting the method, the impacts of the delay on the stability of a system can be reduced, and the dynamic performance quality of the system can be improved. The method is applicable to dynamic compensation and control of the network control system, wherein a mathematical model of a controlled object is known, a network only exists between the transducer (controller) node and the actuator node, the network allows a certain quantity of data packet dropout, and the network delay is constant or time-varying or uncertain.

Description

technical field [0001] The invention relates to a network control system delay compensation method in which the network only exists between the transmitter (controller) node and the actuator node, and belongs to the interdisciplinary field of network communication, computer technology and control technology. Background technique [0002] With the increasing development and cross-penetration of computer technology, network communication technology and control science, the structure of the control system is becoming more and more complex, the spatial distribution is becoming wider and wider, and the requirements for system control performance are getting higher and higher. A networked control system (Networked control systems, NCS) is a complex fully distributed control system integrating a communication network and a control system. It is a closed-loop feedback control system based on a real-time communication network. It is suitable for a typical structural block diagram of a...

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Problems solved by technology

[0003] The advantage of the network control system is that it can realize resource sharing and remote distributed control. The system is modularized, integrated, and low in cost. Shared by two nodes, when the transmitter (controller) and the actuator exchange data through the network, data multi-path transmission, multi-packet transmission, data collision, network connection interruption and other phenomena are inevitable, which makes the network control system produce Some problems that need to be studied and solved urgently: Uncertain data transmission, time-varying transmission cycle, data transmission delay and other problems make the network control system lose its stability, integrity, causality and determinism. Traditional control theory can no longer Directly used in the analysis and design of networked control systems, the control theory and control method of networked control systems must be re-evaluated and established according to the characteristics of networked control systems.

[0007] 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.

[0008] 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 (controller) node and the 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 specific network protocols, network load, and network topology, and there may be deviations in the estimation or identification of network delay.

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