CN101995873A - Method for compensating network delay between transducer and (control) actuator in layered structure - Google Patents
Method for compensating network delay between transducer and (control) actuator in layered structure Download PDFInfo
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Abstract
The invention provides a method for compensating network delay between transducer node and (control) actuator node in network control system in layered structure, belonging to the technical field of network communication, computer and control. A network data transmission process between a real transducer node and (control) actuator node is adopted to substitute a network delay compensation model between the two, measurement, estimation, observation or identification of network data transmission delay between nodes is avoided, and the requirement of synchronization to clock signal of node is eliminated. By adopting the method, influence of delay to system stability can be reduced, and dynamic performance quality of system can be improved. The invention is applicable to network control system in layered structure the controlled object mathematic model of which is known, or uncertain or difficult to be determined owning to interference and communication network of which is only existed between the transducer node and (control) actuator node and is applicable to dynamic compensation and control on network delay more than one or even dozens of sampling periods.
Description
Technical field
The present invention relates in the network control system of hierarchy, network is present in the network delay compensation method between transmitter and (control) actuator node, belongs to the network control system technical field.
Background technology
Along with calculated performance, the develop rapidly of network service and intelligent transfer technology, make computer control system carry out the transition to collecting and distributing control mode from traditional centralized control mode, the Fieldbus Control mode, until based on network distributed control mode now. utilize communication network to realize the transmitter that typical space distributes, information interaction between (control) actuator, to reach the FEEDBACK CONTROL of controlled device, such class control system is referred to as network control system (Networked control systems, NCS), be applicable to network control system typical structure block diagram of the present invention as shown in Figure 1.
Adopt point-to-point information lossless load mode to compare with traditional control system, NCS can realize that by data network even wireless network the big system under the complex environment controls and Long-distance Control, and it is good to have interactivity, reduce system wiring, be easy to expansion and maintenance, plurality of advantages such as the flexibility of system and reliability have been increased, these all are that traditional control system is incomparable. also make simultaneously the analysis of system and design become complicated singularly. because the network bandwidth is limited and shared by each node of system, when passing through the network exchange data between transmitter node and the control actuator node, may there be many bag transmission in data, multi-path transmission, and that network also may exist is congested, connect phenomenons such as interruption, make NCS lose steadiness, integrality, causality and determinacy. the existence of time delay can reduce the control performance quality of system, cause system's instability, can cause system to break down when serious.
If the network delay known stochastic variable that is distribution character, then can be considered as a stochastic system to network control system, utilize the theory and the method for STOCHASTIC CONTROL to carry out Design ﹠ Analysis of System, but because network delay is relevant with concrete factors such as procotol, offered load size and network topology structure, know fully in advance its accurately probability distribution be impossible; When being, network delay becomes, uncertain time delay, can adopt robust control, adaptive control, methods such as Based Intelligent Control become the network control system of time delay when having and analyze and design, but because the simple method that changes control strategy that adopts is come the corrective network time delay, its prerequisite is the variation of network delay to be regarded as the broad sense controlled device or its parameter changes, cause that systematic error changes, and then implement control method such as intelligence, be a kind of passive control methods in essence, its control effect usually when time delay is less effect better, but be difficult to adapt to the bigger situation of time delay fluctuation.
Exist only in transmitter and the internodal network control system of (control) actuator at as shown in Figure 2 network, its input R (s) and closed loop transfer function, of exporting between (s) are
In the formula: C (s) is a controller; G (s) is a controlled device; τ represents network delay that network data is produced when the transmitter node is transferred to (control) actuator node.
Owing to there is the exponential term e of network delay τ in the denominator of the closed loop transfer function, shown in the equation (1)
-τ s, the existence of time delay will worsen the control performance quality of system, even cause system's loss of stability, when serious system be broken down.
Reduce time delay to the sex key of system stability, just be to realize exponential term e the network delay τ between transmitter node and (control) actuator node
-τ sFrom the denominator of equation (1), remove, promptly realize not comprising in the closed loop secular equation exponential term of network delay, yet and then realization is to the compensating action of network delay., realize compensation to network delay, at first must know the size of network delay. at present, usually the method that adopts is by the measurement to network delay τ both at home and abroad, come the influence of delay compensation to system stability. still, owing to need satisfy the synchronous requirement of node clock signal to the accurate measurement of network delay, if adopt hardware to realize that node clock signal is synchronous fully, then need bigger economy input; If adopt software position signal, when then between node, transmitting, may meet with the influence of network delay owing to correction signal, be difficult to realize that nodal clock is synchronous fully; If adopt size to network delay is estimated, identification or forecast method obtain network delay, then must know the accurate probability distribution of network delay, or mathematical model accurately, but because the size of network delay may be at random, become in the time of also may being, its value is relevant with concrete factors such as procotol, offered load size and network topology structure, all may have error to the estimation or the identification of network delay.
Therefore, how to exempt transmitter node and the synchronous requirement of (control) actuator node clock signal, release is to the estimation or the identification of network delay between transmitter node and (control) actuator node, can obtain simultaneously between the node time delay value accurately again, and then realize compensation and control to network delay between transmitter node and (control) actuator node, having become network control system needs one of key issue that solves in studying.
Summary of the invention
In order to solve the problems of the technologies described above, to the invention provides a kind of network that relates to and exist only in hierarchy network control system delay compensation method between transmitter node and (control) actuator node.
Purpose of the present invention:
Exist only in the hierarchy network control system between transmitter node and (control) actuator node at network, the difficult problem of network delay " indeterminacy ", the present invention proposes a kind of release requirement synchronous to node clock signal, also exempt simultaneously the delay compensation method of measurement, estimation or identification, realize real-time, online and dynamic compensation network delay to network delay.
The method that the present invention adopts is:
The first step: adopt the transmitter node to replace the compensation model of network delay therebetween to real network data transmission process between (control) actuator node, thereby the system that structurally realizes does not comprise the compensation model of network delay therebetween. how complicatedly and uncertain no matter have from the transmitter node to the network path (control) actuator node, also no matter include therebetween what routers or (with) intermediate link, the network delay that information flow experienced is exactly a real network delay in the control procedure, has just realized the compensate function to its time delay in the information stream transmission process.
Second step: at network control system shown in Figure 2, the delay compensation of enforcement the inventive method is as shown in Figure 3.
In Fig. 3, be from the input R (s) of system and the closed loop transfer function, between the output Y (s)
In the denominator of closed loop transfer function,, do not comprise the exponential term e of network delay τ shown in the formula (2)
-τ s, promptly realized in its closed loop secular equation 1+C (s) G (s)=0, not comprising the exponential term of network delay, thereby eliminated the influence of network delay system stability, improved the control performance quality of system, realized compensate function to network delay.
The scope of application of the present invention:
The present invention is applicable to that network exists only in the hierarchy network control system between transmitter node and (control) actuator node, the controlled device mathematical model is known or be uncertain of, or interference is difficult to determine, its network delay can be at random, time becomes or uncertain, also can be known or definite network delay compensation and control.
The invention is characterized in that this method may further comprise the steps:
1, when transmitter node during, will adopt mode A to carry out work by the periodic sampling signal triggering;
2, when the transmitter node with the output signal Y (s) of controlled device G (s) by the feedback network path when (control) actuator node transmits, will adopt mode B to carry out work;
3, when (control) actuator node is triggered by signal Y (s), will adopt mode C to carry out work.
The step of mode A comprises:
A1: the transmitter node works in the time type of drive, and its trigger pip is the periodic sampling signal;
A2: after the transmitter node is triggered, the output signal Y (s) of controlled device G (s) is sampled.
The step of mode B comprises:
B1: the transmitter node transmits by the feedback network path signal Y (s) to (control) actuator node.
The step of mode C comprises:
C1:(control) the actuator node works in event driven manner, is triggered by the signal Y (s) from the feedback network path;
C2: the given signal R of system (s) is added and subtracted mutually with signal Y (s) from the feedback network path, obtain error signal e
1(s);
C3: with e
1(s) with from the output signal Y (s) of in-situ transducer node subtract each other, obtain error signal e
2(s);
C4: according to error signal e
2(s) size is implemented conventional control or Intelligent Control Strategy C (s), and its output signal is u (s);
C5: u (s) as carrying out drive signal, is implemented control to controlled device G (s).
4, delay compensation method of the present invention is characterized in that system comprises unit such as transmitter, (control) actuator and controlled device, and each unit carries out work according to the working method of setting separately.
5, delay compensation method of the present invention, it is characterized in that using replacing network delay compensation model therebetween from the transmitter node to the network data transmission process (control) actuator node really, thereby the system that structurally realizes does not comprise the compensation model of network delay therebetween.
6, delay compensation method of the present invention is characterized in that controller C (s) is used for reducing (elimination) error signal e
2(s) to the influence of dynamic performance.
7, delay compensation method of the present invention, it is characterized in that the output signal Y (s) by the controlled device G (s) of feedback network path transmission: it is in running order to can be used for triggering (control) actuator node on the one hand, and controlled device G (s) is implemented control action; On the other hand, can be used for other node realization resource sharing in the network.
8, delay compensation method of the present invention is characterized in that need not to know fully the mathematical model of controlled device G (s), can realize the full remuneration to the feedback network path time delay, improves the control of quality of system.
9, delay compensation method of the present invention is characterized in that exempting measurement, estimation or the identification of transmitter node to the network delay (control) actuator node from structure.
10, delay compensation method of the present invention is characterized in that exempting transmitter node and the synchronous requirement of (control) actuator node clock signal from structure.
11, delay compensation method of the present invention is characterized in that realizing that from structure the enforcement of network delay compensation method is irrelevant with the selection of concrete control strategy.
12, delay compensation method of the present invention is characterized in that realizing that from structure the enforcement of network delay compensation method is irrelevant with the selection of concrete network communication protocol.
13, delay compensation method of the present invention, the mode A of it is characterized in that are applicable to transmitter node periodic sampling and signal are handled.
14, delay compensation method of the present invention, the mode B of it is characterized in that are applicable to transmitter node transmitting network data.
15, delay compensation method of the present invention, the mode C of it is characterized in that are applicable to (control) actuator node enforcement control algolithm and controlled device are implemented controlling and driving.
The present invention has following advantage:
1, because from measurement, estimation or the identification of structure release to network delay, exempted the synchronous requirement of node clock signal, and then avoided the inaccurate evaluated error that causes of time delay estimation model, avoided the required waste that expends the node storage resources of time delay identification, also avoided simultaneously because the compensating error that " the empty sampling " that time delay causes or " many samplings " bring.
2, irrelevant owing to realizing with the selection of concrete network communication protocol from structure, thereby both be applicable to the network control system that adopts wired network protocol, also be applicable to the wireless network protocol network control system; Both be applicable to the deterministic network agreement, also be applicable to the procotol of uncertainty.
3, owing to realized with the selection of concrete control strategy irrelevantly from structure, thereby both can be used for adopting the network control system of conventional control, also can be used for the network control system that adopts Based Intelligent Control or adopt complicated control strategy.
4, the inventive method both can be used for constant time delay (comprising no propagation delay time), also can be used at random, time becomes and the nondeterministic network delay compensation.
5, because the present invention adopts is the compensation method that " soft " changes the control system structure, thereby in its implementation procedure, need not to increase again any hardware device, the software resource that utilizes existing network control system intelligent node to carry, just be enough to realize its compensate function, thereby can save hardware investment, be easy to be extended and applied.
Description of drawings
Fig. 1 exists only in transmitter and the internodal network control system block scheme of (control) actuator for network.
Fig. 2 exists only in transmitter and the internodal network control system structural drawing of (control) actuator for network.
Fig. 3 is a network delay compensation method structural drawing between transmitter and (control) actuator node in the hierarchy of the present invention
Exist only in transmitter and the internodal network control system block diagram of (control) actuator at Fig. 1 network, system comprises input signal R, output signal Y, controlled device (G), transmitter (S), the unit such as feedback network path and (control) actuator (C/A). wherein:
Transmitter (S) node adopts the time type of drive to carry out work, and the triggering cycle is h, and controlled device (G) implementation cycle is sampled.
(control) actuator (C/A) node adopts event driven manner to carry out work, output signal by transmitter (S) node triggers by the feedback network path. and its output signal node changes the state of controlled device (G), realizes the control action to controlled device (G).
Transmitter among Fig. 1 (S) node, (control) actuator (C/A) node all is intelligent node, not only possess storage calculation function and communication function, and possess software configuration and control function, these nodes comprise now the hardware such as intelligent node common in the industrial field bus control system (FCS) of extensive use and the Distributed Control System (DCS) or smart machine.
Exist only in transmitter and the internodal network control system structure chart of (control) actuator at Fig. 2 network: system comprises input signal R, output signal Y, and controlled device (G), feedback network postpones e-τsWith unit such as controller C.
Data transfer is experiencing the impact from the transmitter node to the network transfer delay τ (control) actuator node among Fig. 2. time delay and concrete procotol, the factors such as offered load size and network topology structure are relevant, present or permanent, or at random, or the time become, or the characteristic such as uncertain, measurement for network delay, or estimate, or observation, yet or identification becomes the crucial precondition that realizes its compensation., the distributivity of each node by network connection is so that each node in the network control system is difficult to satisfy the requirement of clock synchronous. simultaneously, because the randomness of network delay and sudden will accomplish that each step can both Accurate Prediction be impossible.
Method for compensating network delay structure chart between transmitter and (control) actuator node in Fig. 3 hierarchy of the present invention: system comprises input signal R, output signal Y, and controlled device (G), feedback network postpones e-τsWith unit such as controller C.
Owing to do not comprise the prediction model of network delay among Fig. 3, exempted at random, time becomes or measurement, estimation, observation or the identification of uncertain network delay τ, also exempted simultaneously transmitter node and the synchronous requirement of (control) actuator node clock signal, realized the exponential term e with network delay τ-τsFrom the closed loop characteristic equation, eliminate, thereby reduced the impact of time delay to the stability of a system, improved the control performance quality of system, realized compensation and control to network delay.
Embodiment
To make clearer above-mentioned and other feature and advantage of the present invention of those of ordinary skill in the art by describing exemplary embodiment of the present invention in detail below with reference to accompanying drawing 3.
Concrete implementation step is as described below:
The first step: the transmitter node that works in the time type of drive carries out periodic sampling to the output signal Y (s) of controlled device G (s); Y (s) is transmitted to (control) actuator node by the feedback network path;
Second step: (control) actuator node that works in event driven manner is fed network path signal Y (s) and triggers, and the given signal R of system (s) is added and subtracted mutually with Y (s), obtains error signal e
1(s); With e
1(s) with from the output signal Y (s) of in-situ transducer node subtract each other, obtain error signal e
2(s); To signal e
2(s) implement conventional control or Intelligent Control Strategy C (s), its output signal is u (s); U (s) as carrying out drive signal, is implemented control to controlled device G (s);
The 3rd step: return the first step.
The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.
The content that is not described in detail in this instructions belongs to this area professional and technical personnel's known prior art.
Claims (11)
1. network delay compensation method between transmitter and (control) actuator in the hierarchy is characterized in that this method may further comprise the steps:
(1). when transmitter node during, will adopt mode A to carry out work by the periodic sampling signal triggering;
(2). when the transmitter node with the output signal Y (s) of controlled device G (s) by the feedback network path when (control) actuator node transmits, will adopt mode B to carry out work;
(3). when (control) actuator node is triggered by signal Y (s), will adopt mode C to carry out work;
2. compensation method according to claim 1 is characterized in that the step of described mode A comprises:
A1: the transmitter node works in the time type of drive, and its trigger pip is the periodic sampling signal;
A2: after the transmitter node is triggered, the output signal Y (s) of controlled device G (s) is sampled.
3. compensation method according to claim 1 is characterized in that the step of described mode B comprises:
B1: the transmitter node transmits by the feedback network path signal Y (s) to (control) actuator node.
4. compensation method according to claim 1 is characterized in that the step of described mode C comprises:
C1:(control) the actuator node works in event driven manner, is triggered by the signal Y (s) from the feedback network path;
C2: the given signal R of system (s) is added and subtracted mutually with signal Y (s) from the feedback network path, obtain error signal e
1(s);
C3: with e
1(s) with from the output signal Y (s) of in-situ transducer node subtract each other, obtain error signal e
2(s);
C4: according to error signal e
2(s) size is implemented conventional control or Intelligent Control Strategy C (s), and its output signal is u (s);
C5: u (s) as carrying out drive signal, is implemented control to controlled device G (s).
5. method according to claim 1 is characterized in that system comprises unit such as transmitter, (control) actuator and controlled device, and each unit carries out work according to the working method of setting separately.
6. method according to claim 1, it is characterized in that using replacing network delay compensation model therebetween from the transmitter node to the network data transmission process (control) actuator node really, thereby the system that structurally realizes does not comprise the compensation model of network delay therebetween.
7. method according to claim 1 is characterized in that controller C (s) is used for reducing (elimination) error signal e
2(s) to the influence of dynamic performance.
8. method according to claim 1 is characterized in that need not to know fully the mathematical model of controlled device G (s), can realize the full remuneration to the feedback network path time delay, improves the control of quality of system.
9. method according to claim 1, it is characterized in that exempting of measurement, estimation or the identification of transmitter node, exempt transmitter node and the synchronous requirement of (control) actuator node clock signal to the network delay (control) actuator node from structure.
10. method according to claim 1 is characterized in that realizing that from structure the enforcement of network delay compensation method is irrelevant with the selection of concrete control strategy, and is irrelevant with the selection of concrete network communication protocol.
11. method according to claim 1, the mode A of it is characterized in that is applicable to transmitter node periodic sampling and signal is handled; Mode B is applicable to transmitter node transmitting network data; Mode C is applicable to (control) actuator node enforcement control algolithm and controlled device is implemented controlling and driving.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113328941A (en) * | 2021-05-26 | 2021-08-31 | 北京航空航天大学 | Minimum delay routing algorithm for dynamic uncertain network |
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Non-Patent Citations (2)
| Title |
|---|
| 《系统工程与电子技术》 20090331 杜锋等 基于改进Smith预估补偿的网络控制系统研究 661-665 1-11 第31卷, 第3期 * |
| 《西南交通大学学报》 20100228 杜锋等 基于新型Smith预估器的网络控制系统 65-69 1-11 第45卷, 第1期 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113328941A (en) * | 2021-05-26 | 2021-08-31 | 北京航空航天大学 | Minimum delay routing algorithm for dynamic uncertain network |
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Application publication date: 20110330 |