Compensation method of random time-delay of external forward and internal feedback path of network cascade control system

Abstract

The invention provides a compensation method of random time-delay of the external forward and internal feedback paths of a network cascade control system, belonging to the technical field of the network control system. The method uses the actual external forward network path nodes of the network cascade control system and adopts the network data transmission process between the internal feedback network path nodes to replace the compensation model of network time-delay between the nodes, avoid the measurement, observation, estimation or identification of the network data transmission random time-delay between the nodes and remove the synchronization requirement on the node clock signal. By adopting the method, the influence of the random network time-delay on the system stability can be reduced and the performance quality of system control can be imprved. The method of the invention is suitable for the dynamic compensation and control of random network time-delay when the mathematicalmodels of the main controlled object and auxiliary controlled object are known and the network only exists in the external forward and internal feedback paths of the cascade control system.

Description

technical field [0001] The invention relates to a compensation method for the random network time delay of the external forward and internal feedback paths of a network cascaded control system, belonging to the technical field of network control systems. Background technique [0002] In recent years, the rapid development of computer network technology has triggered profound changes in control technology and the emergence of corresponding new control theories. The feedback control system that forms a closed loop through the network is called network control systems (NCS). [0003] The research on network control system was developed in the middle and late 1990s, and it has become one of the hot spots in the development of automatic control and network communication technology. Network control system has the advantages of less system connection, convenient expansion, simple diagnosis and maintenance, and flexible With the advantages of high performance, resource sharing and r...

AI Technical Summary

Problems solved by technology

[0009] (2) The network delay that occurs in the process of transmitting network data from the previous node to the next node, no matter what prediction or estimation method is used in the previous node, it is impossible to know in advance the subsequent network delay Accurate value. Time delay leads to system performance degradation and even system instability, and also brings difficulties to the analysis and design of the control system.

[0014] Since the denominator of the closed-loop transfer function shown in equation (1) includes the network delay τ 1 and τ 2 index term of and 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.

[0015] The key to reducing the impact of delay on system stability is whether the network delay τ between the main transmitter (controller) node and the execution (secondary controller) node can be realized. 1 index term of and the network delay τ between the secondary transmitter and the executive (secondary controller) node 2 index term of It is removed from the denominator of equation (1), that is, the exponential term of all network delays is not included in the closed-loop characteristic equation of the system, and then the compensation of network delay is realized. However, to realize the compensation of network delay, first, Know the size of the network delay. At present, the method commonly used at home and abroad is to measure the network delay τ 1 and τ 2 measurement to compensate for the time delay τ 1 and τ 2 The impact on system stability. However, due to the network delay τ 1 and τ 2 The accurate measurement of the node needs to meet the synchronization requirements of the node clock signal. If hardware is used to realize the complete synchronization of the node clock signal, a large economic investment is required; if the software is used to correct the clock signal, the correction signal may encounter Due to the influence of network delay, it is difficult to achieve complete synchronization of node clocks. If the method of estimating, observing, identifying or predicting network delay is used to obtain the size of network delay, the accurate probability distribution of network delay must first be known, or An accurate mathematical model, but because the network delay is related to factors such as specific network protocols, network load, and network topology, there may be deviations in the estimation, observation, identification or prediction of network delay.

Images