A kind of uncatalyzed coking H of nonlinear network networked control systems∞Fault tolerant control method
Technical field
The present invention relates to network control system and faults-tolerant control, particularly relate to a kind of non-thread with time delay and packet loss
The uncatalyzed coking H of property network control system∞Fault tolerant control method.
Background technology
The closed-loop control system formed by communication network is referred to as network control system (networked control
Systems, be abbreviated NCSs), NCSs have convenient for installation and maintenance, motility is high and is prone to the advantages such as reconstruct.But, communication network
Introducing result in system and there is problems in that 1) network delay: data when communication network transmission because network blockage or
The reasons such as external interference so that there is network delay problem in network control system;2) packet loss: in data transmission procedure because
The problem that the reason such as network blockage and resource contention can cause data-bag lost.The most extraneous uncertain factor may result in
Systematic function reduces even unstability.Therefore, make NCSs have fault-tolerant ability and to keep preferable interference free performance to have the heaviest
The theory significance wanted and more practical value.
For time delay and packet loss problem present in NCSs, a lot of scholars and expert have done numerous studies.Zheng Ying etc. exist
In paper " robust Fault-Tolerant Control of uncertain network networked control systems ", obtained by Time Delay Estimation Method and the online time delay method that obtains
Obtain time-vary delay system, and drive controller, the method for event-driven executor by clock, use STATE FEEDBACK CONTROL strategy to grind
Study carefully Robust Integrity problem;Li Wei etc. are at the paper " H of nonlinear network networked control systems based on T-S fuzzy model∞Robust
Faults-tolerant control " in, for there is the non-linear NCSs of time delay and packet loss, modeling based on T-S fuzzy model, have studied at sensor
Or when there is failure of removal in executor, H∞The method for designing of Robust Fault-tolerant Controller.In research in terms of above-mentioned faults-tolerant control only
Consider fixing controller, have certain limitation.Also some changes can be produced in view of controller parameter is interfered by outside
Changing, take non-fragiie control to seem particularly significant, non-fragile controller can make system keep rapidly stable.Horse is defended the country etc. at paper
" the uncatalyzed coking H of networking nonlinear system∞Control " in, for there is the time delay being less than a sampling period and meeting Ma Erke
The non-linear NCSs of husband's drop probabilities, have studied uncatalyzed coking H∞The method for designing of controller, but this research does not accounts for performing
The problem of device generation failure of removal.Cao Hui is superfine in paper " the saturated uncertain NCS uncatalyzed coking robust Fault-Tolerant Control of executor ",
For the saturated situation of executor, give the method for designing of uncatalyzed coking Robust Fault-tolerant Controller, but this is complete only for executor
Lost efficacy or the most normal situation, can not meet the needs of actual state.
Summary of the invention
For above-mentioned problems of the prior art, the invention provides the non-of a kind of nonlinear network networked control systems
Fragile H∞Fault tolerant control method.Consider nonlinear network networked control systems Parameter Perturbation, time delay, packet loss and executor occur with
Under machine failure condition, devise uncatalyzed coking feedback of status H∞Fault-tolerant controller so that nonlinear network networked control systems is above-mentioned
In the case of remain to keep stable, and can be by Disturbance Rejection at given level.
The technical solution adopted in the present invention is: the uncatalyzed coking H of a kind of nonlinear network networked control systems∞Faults-tolerant control side
Method, comprises the following steps:
1) the nonlinear networked control system model of closed loop is set up:
Wherein, during σ (k)=0, represent that current time data are transmitted normally in a network;During σ (k)=1, represent current time number
Lose according to when being transmitted by network;
Wherein,x(k)∈RnFor state vector, u (k) ∈ RPFor controlling
Input quantity, w (k) ∈ RlExternal disturbance and w (k) ∈ L for finite energy2[0, ∞), z (k) ∈ RqFor controlling output, f (k, x
(k)) meet Lipschitz condition Nonlinear Vector item, | | f (k, x (k)) | |≤| | F1x(k)||;A∈Rn×n、B0∈Rn×p、B1
∈Rn×p、C∈Rq×n、D∈Rq×l、R∈Rq×lAnd F1∈Rn×nFor constant matrices;ΔA∈Rn×n、ΔB0∈Rn×pWith Δ B1∈Rn×p
It is time delay and the uncertain part of systematic parameter perturbation, there is following form:
[ΔA ΔB0 ΔB1]=D1F(k)[E1 E2 E3]
Wherein, D1∈Rn×n、E1∈Rn×n、E2∈Rn×pAnd E3∈Rn×pFor constant matrices, F (k) ∈ Rn×nFor meeting following bar
The unknown uncertain matrix of part, its element Lebesgue can survey and bounded F (k)TF(k)≤I;M=diag{m1,m2,…,mn,
m1,m2,…,mnFor n orthogonal stochastic variable, mi=1 is that executor is normal, mi=0 thoroughly lost efficacy for executor, when 0
< miDuring < 1, representing executor's partial failure, executor occurs the probability of random fault to meet Bernoulli distribution, thus may be used
? Variance be The state feedback controller is taked to beK∈Rp×nFor controlling gain battle array,
Δ K is for controlling gain perturbation battle array.Δ K=D1F(k)E4, E4∈Rn×pFor constant matrices.
1) structure includes the Lyapunov function of packet loss information:
Wherein, Pi=diag{Pi11,Pi22, i=0,1, Pi11∈Rn×nAnd Pi22∈Rp×pFor unknown positive definite symmetric matrices, number
Can describe by the Markov chain with two states according to transmitting procedure, its state-transition matrix is P=[pij], pij=
Pr{ σ (k+1)=j | σ (k)=i},
2) utilize Lyapunov Theory of Stability and LMI to analyze method, obtain nonlinear networked control
System Stochastic stable and H∞The sufficient condition that fault-tolerant controller exists:
For following linear MATRIX INEQUALITIES:
Wherein,Λ22=diag{-ε1I,-ε3I,-ε2I+H1,
Λ44=diag{-ε2I,-ε1I,-ε1I}, Λ55=-γ2I,
Λ65=[RT 0 RT 0]T
Λ75=D, Λ77=-I
Θ22=diag{-ε1I,-ε4I},
Θ44=diag{-ε4I,-ε1I,-ε1I}, Θ55=-γ2I,
Θ65=[RT 0 RT 0]T
Θ75=D, Θ77=-I, γ are Disturbance Rejection rate;
P011,P022,P111,P122, εiAnd matrix Y ∈ R (i=1,2,3,4)p×nFor known variables, its dependent variable is all known
, can draw according to systematic parameter or directly give, utilize Matlab LMI workbox to solve, if there is symmetry just
Set matrix P011,P022,P111,P122, matrix Y and scalar εi> 0 (i=1,2,3,4), then nonlinear network networked control systems be with
Machine stable and there is H∞Performance γ, uncatalyzed coking fault-tolerant controller gain matrix isAnd step 4 can be proceeded);
If above-mentioned known variables does not solve, then nonlinear network networked control systems is not Stochastic stable and does not have H∞Performance γ,
Uncatalyzed coking fault-tolerant controller gain matrix can not be obtained, also cannot carry out step 4);
3) condition that minimal disturbances suppression ratio γ can optimize is given:
Make e=γ2If following optimization problem is set up:
P011> 0, P022> 0, P111> 0, P122> 0, εi> 0 (i=1,2,3,4)
Then can obtain closed loop nonlinear network networked control systems and meet uncatalyzed coking H∞Under the conditions of faults-tolerant control, system is
Microvariations suppression ratioUncatalyzed coking fault-tolerant controller gain matrix K also can be optimised for simultaneously
Compared with prior art, the invention have the advantages that
1) the present invention is directed to the nonlinear network networked control systems with time delay and packet loss, simultaneously take account of model parameter
Uncertainty, controller gain perturbations and the impact of external disturbance, establish the nonlinear networked control system model of closed loop, give
Stability and the H of system when executor occurs random fault are gone out∞The solution of faults-tolerant control.
2) present invention considers executor the situation of random fault occurs, and the probability of happening of random fault meets
Bernoulli is distributed, and has more practical significance.
3) present invention optimizes minimal disturbances suppression ratio γ so that nonlinear network networked control systems has the most anti-dry
Immunity energy.
Accompanying drawing explanation
Accompanying drawing 1 is the flow chart that nonlinear network networked control systems fault-tolerant controller solves;
Accompanying drawing 2 is carried out γ after device does not occur random fault and optimizes*The nonlinear networked control of closed loop when=0.8228
System mode response diagram processed;
Accompanying drawing 3 is γ after an executor occurs random fault and optimizes*Closed loop when=0.8210 is nonlinear networked
Control system condition responsive figure;
Accompanying drawing 4 is γ after executor's complete failure and optimization*The nonlinear networked control of closed loop when=0.8677
System mode response diagram.
Detailed description of the invention
Below in conjunction with the accompanying drawings the detailed description of the invention of the present invention is described further.
Referring to the drawings 1, the uncatalyzed coking H of a kind of nonlinear network networked control systems∞Fault tolerant control method, including following step
Rapid:
Step 1: set up the nonlinear networked control system model of closed loop
Network control system data transmission procedure can describe by the Markov chain with two states, its state
Transfer matrix is P=[pij], pij=Pr{ σ (k+1)=j | σ (k)=i},σ (k)=0
Transmit for data normal in a network, lose when σ (k)=1 is transmitted by network for data.
When σ (k)=0, and when network inducement delay is less than a sampling period, it is contemplated that the uncertainty of systematic parameter,
Then the discrete time model of controlled system is
Wherein,x(k)∈RnFor state vector, u (k) ∈ RPFor controlling
Input quantity, w (k) ∈ RlExternal disturbance and w (k) ∈ L for finite energy2[0, ∞), z (k) ∈ RqFor controlling output, f (k, x
(k)) meet Lipschitz condition Nonlinear Vector item, | | f (k, x (k)) | |≤| | F1x(k)||;A∈Rn×n、B0∈Rn×p、B1
∈Rn×p、C∈Rq×n、D∈Rq×l、R∈Rq×lAnd F1∈RnFor constant matrices;ΔA∈Rn×n、ΔB0∈Rn×pWith Δ B1∈Rn×pIt is
Time delay and the uncertain part of systematic parameter perturbation, have a following form:
[ΔA ΔB0 ΔB1]=D1F(k)[E1 E2 E3]
Wherein, D1∈Rn×n、E1∈Rn×n、E2∈Rn×pAnd E3∈Rn×pFor constant matrices, F (k) ∈ Rn×nFor meeting following bar
The unknown uncertain matrix of part, in order to describe the random fault of the generation of executor, introduces ffault matrix M, and its form is
M=diag{m1,m2,…,mn} (2)
Wherein, m1,m2,…,mnFor n orthogonal stochastic variable, mi=1 is that executor is normal, mi=0 is executor
Thoroughly lost efficacy, as 0 < miDuring < 1, represent executor's partial failure.Executor occurs the probability of random fault to meet
Bernoulli is distributed, and thus can obtain Variance beIn addition
Can also obtain:
Wherein,
Design point feedback controller is
Wherein, K ∈ Rp×nFor controlling gain battle array, Δ K is for controlling gain perturbation battle array.Δ K=D1F(k)E4, E4∈Rn×pFor often
Matrix number.
If augmentation is vectorialWhen executor occurs random fault, uncertain closed loop is non-linear
Network control system is
Wherein,
When σ (k)=1, packet is lost in network transmits, and now uses the value of previous moment, i.e. u (k)=u (k-
1), then network control system model is
Wherein,
Composite type (4) and formula (5), in the case of executor occurs random fault, closed loop nonlinear network networked control systems can
To be described as following Markov jump system:
Step 2: structure includes the Lyapunov function of packet loss information
Wherein, Pi=diag{Pi11,Pi22, i=0,1, Pi11∈Rn×nAnd Pi22∈Rp×pFor unknown positive definite symmetric matrices.
Due to fT(k)f(k)≤xT(k)F1 TF1X (k), accordingly, there exist ε1> 0, makes ε1xT(k)F1 TF1x(k)-ε1fT(k)f
(k)≥0。
When external disturbance w (k)=0:
Wherein,
Step 3: utilize Lyapunov Theory of Stability and LMI to analyze method, obtain nonlinear networked
Control system Stochastic stable and H∞The sufficient condition that fault-tolerant controller exists, step is as follows:
Step 3.1: based on step 2) the Lyapunov function that constructs, utilize Lyapunov Theory of Stability and linear matrix
Inequality analyzes method, first determines whether the stochastic stability of nonlinear network networked control systems, obtains nonlinear networked control
The sufficient condition of system Stochastic stable.
AssumeAs i=0, according to Schur lemma:
Δ A, Δ B0, Δ B1, the expression formula of Δ K substitutes into formula (8), and after converting according to Schur lemma, inequality is same
Shi Zuocheng and the right side are taken advantage ofObtain
Wherein,
∏44=diag{-ε2I,-ε1I,-ε1I},
In like manner, as i=1, inequality can be obtained:
Wherein,
Ω44=diag{-ε4I,-ε1I,-ε1I},
According to Lyapunov Theory of Stability, filling of the nonlinear network networked control systems Stochastic stable shown in formula (6)
Point condition is: when external disturbance w (k)=0, there is symmetric positive definite matrix P011,P022,P111,P122, matrix Y ∈ Rp×nAnd scalarLMI (9) and (10) are set up.When the sufficient condition of step 3.1 is set up, then perform
Step 3.2;If the sufficient condition of step 3.1 is false, then system is not Stochastic stable and H∞Fault-tolerant controller is not deposited
, it is impossible to perform step 3.2.
Step 3.2: under zero initial condition, definition:
Wherein,
IfAs i=0, according to Schur lemma, can obtain with lower inequality:
Wherein, Λ11=∏11, Λ21=∏21, Λ22=∏22, Λ33=∏33, Λ43=∏43, Λ44=∏44, Λ66=
∏55, Λ61=∏51, Λ63=∏53, Λ64=∏54, Λ66=∏55, Λ55=-γ2I, Λ65=[RT 0 RT 0]T,Λ75=D, Λ77=-I
In like manner, as i=1, inequality can be obtained:
Wherein, Θ11=Ω11, Θ21=Ω21, Θ22=Ω22, Θ33=Ω33, Θ43=Ω43, Θ44=Ω44, Θ61=
Ω51, Θ63=Ω53, Θ64=Ω54, Θ66=Ω55, Θ65=[RT 0 RT 0]T, Θ55=-γ2I,Θ75=D,
Θ77=-I.
According to Lyapunov Theory of Stability, the nonlinear network networked control systems shown in formula (6) has H∞Fault-tolerant control
The sufficient condition that device processed exists is: as N → ∞,Set up.
Matlab LMI workbox is utilized to solve, if there is symmetric positive definite matrix P011,P022,P111,P122, matrix
Y∈Rp×nWith scalar εi> 0 (i=1,2,3,4) so that LMI (12) and (13) are set up, then as N → ∞, can
?Then nonlinear network networked control systems (6) is Stochastic stable and has
H∞Performance γ, uncatalyzed coking fault-tolerant controller gain matrixAnd step 4 can be proceeded;If above-mentioned known variables
Do not solve, then nonlinear network networked control systems is not Stochastic stable and does not have H∞Performance γ, it is impossible to obtain uncatalyzed coking and hold
Wrong controller gain matrix, also cannot carry out step 4.
Step 4: provide the condition that minimal disturbances suppression ratio γ can optimize.
Make e=γ2If following optimization problem is set up:
P011> 0, P022> 0, P111> 0, P122> 0, εi> 0 (i=1,2,3,4) (14)
Then can obtain closed loop system (6) and meet uncatalyzed coking H∞Under the conditions of faults-tolerant control, the minimal disturbances suppression ratio of systemUncatalyzed coking fault-tolerant controller gain matrix K also can be optimised for simultaneously
Embodiment:
Use the uncatalyzed coking H of a kind of nonlinear network networked control systems of present invention proposition∞Fault tolerant control method, is not having
When being w (k)=0 in the case of external disturbance, nonlinear closed loop's nonlinear network networked control systems is Stochastic stable.Work as existence
During external disturbance, system is also Stochastic stable and has certain capacity of resisting disturbance.Concrete methods of realizing is as follows:
Step 1: controlled device is closed loop nonlinear network networked control systems, its state-space model is formula (6), given
Its systematic parameter is
C=[0.1 0.1], D=0.6
Assume that disturbing signal is
Markov chain state transition probability matrix is
Assume that system has 2 executors, choose expectation and the variance of 3 kinds of situation random faults.Situation 1: I.e. executor is completely normal, and random fault does not occur;Situation 2: There is random fault in i.e. one executor, another one executor is complete
Normally;Situation 3:I.e. one executor's complete failure, another one executor
The most normal.
Step 2: utilize Matlab LMI workbox to solve, under different random failure situations, try to achieve symmetric positive definite matrix
P011,P022,P111,P122, matrix Y and scalar εi> 0 (i=1,2,3,4), is shown in Table 1;Can be in the hope of non-fragiie control according to table 1
Device K and H∞Performance indications γ, are shown in Table 2;And the result obtained is optimized obtains K*And γ*, concrete outcome, it is shown in Table 3.
The feasible solution of system unknown parameter under table 1 different random fault parameter
Controller parameter before system optimization and H under table 2 different random fault parameter∞Performance indications
Controller parameter after system optimization and H under table 3 different random fault parameter∞Performance indications
Step 3: given original state is x (0)=[1 ,-0.5]T, utilize Matlab LMI workbox in step 2 to solve
As a result, the closed loop nonlinear network networked control systems condition responsive of different random failure condition is simulated with Matlab, such as Fig. 2 extremely
Shown in Fig. 4.
By Fig. 2 to Fig. 4 it can be seen that work as system rejection to disturbance performance γ*Minimum i.e. γ*When=0.8210, the system shape of Fig. 3
State response curve convergence rate is faster than Fig. 2 and Fig. 4;By Fig. 3 and Fig. 4 it can be seen that when executor occurs random fault, even if
There is disturbance in its exterior, and under the effect of controller, system is maintained to asymptotically stability, and system has good
Interference free performance.
It is above presently preferred embodiments of the present invention, not the present invention is made any pro forma restriction, every foundation
The technical spirit of the present invention, to any simple modification made for any of the above embodiments, equivalent variations and modification, belongs to inventive technique
In the range of scheme.