Output feedback control method and controller for heterogeneous sampling system based on switching principle

A non-uniform sampling and output feedback technology, applied in the direction of adaptive control, general control system, control/adjustment system, etc., can solve the problem of long sampling period, uncertain refresh time and sampling interval, unavoidable delay, and random packet loss order and other problems, to achieve the effect of stable index and good effect of simulation examples

Inactive Publication Date: 2018-12-11
XINJIANG UNIVERSITY
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  • Abstract
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  • Application Information

AI Technical Summary

Problems solved by technology

For example, in petroleum, electric power, metallurgy, chemical industry, food, textile and other process industries, some key variables and parameters reflecting the product quality level (such as product Composition, concentration, Kappa value, melt index, etc.), these key variable parameters can only be obtained through manual sampling and laboratory analysis, so the sampling period is long and the sampling interval is irregular
In networked control systems, in order to overcome the negative impact of redundant data on system performance, sensors generally adopt a time-driven working mode, and the sampling time interval is uniformly changed, while actuators generally adopt an event-driven working mode, and their sampling time interval is random, indeterminate
At the same time, due to the limitations of transmission distance, network carrying capacity and communication bandwidth, there will inevitably be delays, packet loss, and out-of-order phenomena during data transmission, which makes the actual sampling frequency non-uniform
[0003] The above non-uniform periodic sampling data system generally also has the following characteristics: the measurement data is obtained at different sampling times and different sampling frequencies; the control input signal and output signal are non-uniform and asynchronous in timing, and the refresh time and sampling interval are uncertain Features; Due to certain resource constraints (which can be caused by communication network bandwidth limitations, smart instrumentation measurement limitations, manual detection time limitations, computing power limitations, etc.), the input signal is time-delayed; therefore, in non-uniform sampling How to overcome the time-varying and uncertain input signal refresh time interval in the system has caused great difficulties in the design of the system controller

Method used

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  • Output feedback control method and controller for heterogeneous sampling system based on switching principle
  • Output feedback control method and controller for heterogeneous sampling system based on switching principle
  • Output feedback control method and controller for heterogeneous sampling system based on switching principle

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] figure 1 The dynamic process of the non-uniform sampling system is given, where S c is a controlled object, its kT+t ik Receive the discrete input signal u(kT+t) generated by the computer at all times ik ), i=1,2,...,p, through the zero-order holder H Γ Generate a continuous signal u(t) as the plant S c input, output y (t) uniformly sampled with a period T, that is, within [kT,kT+T), y (t) = y (kT).

[0057] figure 2 Given the characteristics of the zero-order keeper, the refresh interval is τ ik (τ ik :=t ik -t (i-1)k ), t ik :=τ 1k +τ 2k +...+τ ik (let t 0k =0,t pk =T), T:=τ 1k +τ 2k +...+τ pk = t pk for the frame cycle. In the research, in the non-uniform sampling system, the refresh interval is time-varying and uncertain, then the input signal u(t) can be expressed as:

[0058]

[0059] According to the actual situation, some simplifications have been made to the above non-uniform sampling process:

[0060] 1) In the actual non-uniform sa...

Embodiment 2

[0090] Embodiment 2 Non-uniform sampling system stability analysis

[0091] Lemma: (The nature of Schur's complement) Given a symmetric matrix A>0, a symmetric matrix C>0, and a matrix B, then A+B T CB<0 is equivalent to

[0092] or

[0093]Theorem: Consider the closed-loop non-uniform sampling system (7), if there is a positive scalar λ (0 and So that the following inequalities and equations hold,

[0094]

[0095]

[0096]

[0097]

[0098] Then the system (7) is exponentially stable and has an exponential decay rate

[0099] Proof: Suppose k 1 , k 2 ,...,k i Indicates the switching point of σ(k) in the interval [0,k), satisfying 01 2 i

[0100]

[0101] The Lyapunov function is selected as follows,

[0102]

[0103] where P j >0,Q j >0 and S j >0, j ∈ F 0 , is an undetermined symmetric positive definite matrix. Consider V j (k) along the subsystem S cj Dynamic trajectory changes. From formula...

Embodiment 3

[0142] Embodiment 3 simulation example

[0143] Consider the following controlled objects:

[0144]

[0145] Take the sampling period as T=10ms, divide the sampling interval into ten equal parts, that is, let N=10, take the period T of reading data from the zero-order holder 0 = 1 ms. The controller is taken as

[0146]

[0147] The model of the closed-loop non-uniform sampling system can be described by formula (7). Assume that the maximum delay upper bound τ = 4T 0 =4ms, therefore, there are only five possible values ​​of the input signal delay, that is, τ(k)∈{0,1,2,3,4}ms, and the system (7) contains at most five subsystems. Use these five subsystems with S ci , i=0,1,2,3,4 represent. S ci The system input matrix is ​​given by n 1 (k) and n 0 (k) decides, and [n 1 (k)n 0 The five possible values ​​of (k)] are [0 10], [1 9], [2 8], [3 7], [4 6]. define map[n 1 (k)n 0 (k)]→σ(k):

[0148] [0 10]→0, [1 9]→1, [2 8]→2, [3 7]→3, [4 6]→4

[0149] When delay τ(...

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Abstract

The invention relates to an intelligent control algorithm, and specifically relates to an output feedback control method and controller for a heterogeneous sampling system based on the switching principle. In the heterogeneous sampling system, an input signal is non-uniformly refreshed in one frame period, and an output signal is uniformly sampled. According to the invention, a switching system method is used for solving a problem of refreshing time uncertainty, and the method employs a strategy that the frequency that a non-uniform retaining appliance reads the data is higher than the sampling frequency of a sensor, takes the refreshing time interval as a time delay variable. The system dynamic changes under different time delay conditions are depicted through different subsystem models,thereby enabling an index time-varying term to be decomposed into a plurality of stationary terms, enabling a changing law of time delay to be converted into a switching law between different submodels, and finally converting the heterogeneous sampling system to be converted into a discrete time switching system comprising a plurality of finite subsystems. The method solves the problems that the heterogeneous sampling system is uncertain in refreshing time interval and the design of a system controller is difficult under the time-varying condition.

Description

technical field [0001] The invention relates to an intelligent control algorithm, in particular to an output feedback control method and a controller of a non-uniform sampling system based on a switching principle. Background technique [0002] With the development of modern industry, advanced computer technology, control technology, and communication technology have been adopted. In the era of 3C integration, more and more systems have adopted multiple operating frequencies, which is called multi-rate sampling data system, referred to as multi-rate system. With the development of contemporary industrial production, there is also a more common multi-sampling rate system, that is, a non-uniform sampling data system in which input signal refresh and / or output signal sampling present unequal time intervals. For example, in petroleum, electric power, metallurgy, chemical industry, food, textile and other process industries, some key variables and parameters reflecting the produ...

Claims

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Application Information

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IPC IPC(8): G05B13/04
CPCG05B13/042
Inventor 王宏伟连捷
Owner XINJIANG UNIVERSITY
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