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Noname manuscript No. (will be inserted by the editor) Quantized State Feedback-Based H Control for Nonlinear Parabolic PDE Systems via Finite-Time Interval Teng-Fei Li · Xiao-Heng Chang · Ju H. Park Received: date / Accepted: date Abstract In this paper, the finite-time H control problem of nonlinear parabolic partial differential equation (PDE) systems with parametric uncer- tainties is studied. Firstly, based on the definition of the quantiser, static state feedback controller and dynamic state feedback controller with quantization are presented, respectively. The finite-time H control design strategies are subsequently proposed to analyze the nonlinear parabolic PDE systems with respect to the effect of quantization. And by constructing appropriate Lya- punov functionals for the studied systems, sufficient conditions for the exis- tence of the feedback control gains and the quantizer’s adjusting parameters which guarantee the prescribed attenuation level of H performance are ex- pressed as nonlinear matrix inequalities. Then, by using some inequalities and decomposition technic, the nonlinear matrix inequalities are transformed to standard linear matrix inequalities (LMIs). Furthermore, the optimal H con- trol performances are pursued by solving optimization problems subject to the LMIs. Finally, to illustrate the feasibility and effectiveness of the finite-time H control design strategies, an application to the catalytic rod in a reactor is explored. Keywords Parabolic PDE · Quantization · Finite-time · LMIs ·H control Teng-Fei Li · Xiao-Heng Chang( ) School of Information Science and Engineering, Wuhan University of Science and Technology, Wuhan, 430081, People’s Republic of China E-mail: [email protected] Ju H. Park ( ) Department of Electrical Engineering, Yeungnam University, Kyongsan 38541, Republic of Korea E-mail: [email protected]

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Page 1: Quantized State Feedback-Based H Control for Nonlinear

Noname manuscript No.(will be inserted by the editor)

Quantized State Feedback-Based H∞ Control forNonlinear Parabolic PDE Systems via Finite-TimeInterval

Teng-Fei Li · Xiao-Heng Chang ·Ju H. Park

Received: date / Accepted: date

Abstract In this paper, the finite-time H∞ control problem of nonlinearparabolic partial differential equation (PDE) systems with parametric uncer-tainties is studied. Firstly, based on the definition of the quantiser, static statefeedback controller and dynamic state feedback controller with quantizationare presented, respectively. The finite-time H∞ control design strategies aresubsequently proposed to analyze the nonlinear parabolic PDE systems withrespect to the effect of quantization. And by constructing appropriate Lya-punov functionals for the studied systems, sufficient conditions for the exis-tence of the feedback control gains and the quantizer’s adjusting parameterswhich guarantee the prescribed attenuation level of H∞ performance are ex-pressed as nonlinear matrix inequalities. Then, by using some inequalities anddecomposition technic, the nonlinear matrix inequalities are transformed tostandard linear matrix inequalities (LMIs). Furthermore, the optimal H∞ con-trol performances are pursued by solving optimization problems subject to theLMIs. Finally, to illustrate the feasibility and effectiveness of the finite-timeH∞ control design strategies, an application to the catalytic rod in a reactoris explored.

Keywords Parabolic PDE · Quantization · Finite-time · LMIs · H∞ control

Teng-Fei Li · Xiao-Heng Chang()School of Information Science and Engineering,Wuhan University of Science and Technology, Wuhan, 430081, People’s Republic of ChinaE-mail: [email protected]

Ju H. Park ()Department of Electrical Engineering, YeungnamUniversity, Kyongsan 38541, Republic of KoreaE-mail: [email protected]

Page 2: Quantized State Feedback-Based H Control for Nonlinear

2 Teng-Fei Li et al.

1 Introduction

Many processes in engineering fields and multidimensional dynamical systemsdepend not only on time variable but also on spatial variable inherently, whichmeans that the system performances are decided by both spatial position andtime variable, such as fluid heat exchangers, thermal diffusion processes, anddissipative dynamical systems, et al. [1,2]. And these distributed parametersystems or processes can be frequently described by partial differential equa-tions (PDEs). During the past several decades, an immense amount of inter-esting findings on the control synthesis and stability analysis of PDE systemshave been made by scholars, such as [3–6]. These research achievements aremeaningful for the applications and further studies.

As the constructions of industrial distributed parameter systems governedby PDEs are more and more complicated, higher demands on safety and relia-bility are usually confronted. However, unexpected deviation or uncertaintiesgenerated by external and internal disturbances always occur inherently. Theseuncertainties may lead to system instability and performance degradation ifthey are not appropriately taken account in the controller design. Thus, theissue of control design for PDE systems with uncertain parameters is of practi-cal and theoretical value. Fortunately, valuable researches of controller designand stability analysis for parabolic PDE systems with parametric uncertain-ties have been made by many scholars. For example, with the considerationof uncertain variables presented in the system structure, robust output-basedcontroller design methods for quasi-linear parabolic PDE systems and parabol-ic PDE systems with time-dependent spatial domains can be seen in [7] and [8],respectively. In order to deal with both the parameter variations and boundaryuncertainties, Cheng et al. [9] presented a boundary control law for a class ofparabolic PDE system by using the Volterra integral transformation technic.On the basis of Galerkin method, the nonlinear parabolic PDE system wasdescribed by finite dimensional ordinary differential equation (ODE) model,then predictive control strategy was provided [10] by employing multilayerneural network to parameterize the unknown nonlinearities. And two formu-lations were developed [11] to investigate the sparse solutions for the optimalcontrol problems subject to PDEs with uncertain coefficients. More recently,adaptive feedback control design strategy was proposed [12] to stabilize a classof coefficient matrix uncertain ODE system which is cascaded with uncertainconstant and coefficient matrix parabolic PDE. More researches of uncertainPDE systems can be referred to [13–16] and references therein. On the otherhand, associated with the control issues, the properties of these complicatedsystems are usually required to be considered in a finite-time interval. Thus,the finite-time control is also worth investigating. Fruitful achievements offinite-time control have been made [17–21] for network system. Preciously, thecontrol strategies of semilinear PDE systems in the finite-time interval werealso investigated by Song et al. [22,23].

Recently, networked control systems have attracted more and more atten-tion of scholars due to the development of computer technology and control

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Title Suppressed Due to Excessive Length 3

theory [24]. The application of a multipurpose networked control system usual-ly brings flexible architectures and reduces the budget and installation. Thus,networked control systems have been widely applied in many practical sys-tems [25–30]. To assimilate the advantages of networked control technology,some interesting results have been proposed for the stability analysis and con-trol synthesis of parabolic PDE systems. Such as, Demetriou [31] considered amobile network collocated sensors and actuators for a class of diffusion PDEsystems. By utilizing the distributed in space measurements, a network-basedH∞ filter for parabolic PDEs systems with the objective of enlarging the sam-pling time intervals to reduce the amount of communications while preservinga prescribed error system performance was designed in [32]. Other more recentresearches can be referred in [33,34].

However, due to the limited capability of communication channel, the sig-nal information (e.g., system state, measurement output, and control signal)is usually required to be quantized before it is transmitted into the network.Signal quantization has been widely adopted and studied in recent literatures[35–40]. Nevertheless, accompanied with the signal quantization, quantizationerrors, which may yield system instability and performance degradation, andalso bring difficulties for the system analysis and control, inevitably occur.Thus, the control synthesis for nonlinear systems with the effect of quantiza-tion is significant and necessary. Generally, the quantizer applied in the existingliteratures can be divided into two categories: static quantizer and dynamicone. For static signal quantization, there are some interesting results have beenreported. Such as, event triggered H∞ control problem of parabolic systemswith Markovian jumping sensor faults was studied under the effect of timedelays in [41]. By employing a static logarithmic quantizer for the transmittedmeasurement output, distributed event-triggered networked control strategyfor parabolic systems subjected to diffusion PDEs was proposed in [42]. Con-sidering the measured output signal was quantized by a static quantizer, finite-time based fuzzy bounded control strategy for semilinear PDE systems withmarkov jump actuator failures [22], and H∞ asynchronous control strategyfor nonlinear markov jump distributed parameter systems [23], were provided,respectively. Meanwhile, the H∞ performance for the systems was also widelystudied in the mentioned researches [1,4,7,8,32,41,23].

The above researches are of abyssal significance in the field of control syn-thesis and attract more and more scholars to further studies. Although thereare already various achievements for the controller design of parabolic PDEsystems in the existing literatures, there are still few researches on the quan-tized state feedback control for parameter uncertain nonlinear parabolic PDEsystems via finite-time interval, which is worthy of further study and applica-tion. Moreover, to the best of the authors’ knowledge, it’s realized that theseresults of the H∞ controller design for parabolic PDE systems are mostlyby static feedback control, the finite-time H∞ control of parameter uncertainnonlinear parabolic PDE systems under dynamic feedback controller has notbeen studied yet, which motivates the present research. Thus, the objectiveof this paper is to study the finite-time H∞ control problem for the parame-

Page 4: Quantized State Feedback-Based H Control for Nonlinear

4 Teng-Fei Li et al.

ter uncertain nonlinear parabolic PDE systems via quantized state feedback.Meanwhile, to ensure the prescribed H∞ performance index of the systems,sufficient conditions of the designed controller and quantizer’s adjusting pa-rameters are developed in forms of matrix inequalities. The contributions andnovelties can be summarized as follows:

1) Quantized static/dynamic state feedback control strategies for param-eter uncertain nonlinear parabolic PDE systems via finite-time interval arestudied. Sufficient conditions to obtain the prescribed H∞ performance areprovided in terms of nonlinear matrix inequalities.

2) With the consideration of the system state is transmitted via the digi-tal communication channel, dynamic quantizer which is regarded to be moregeneral and more advantageous than that of a static one is adopted in thispaper. Moreover, the quantization errors generated by the quantizer are welltreated.

3) By using some inequalities and decomposition technic, the nonlinear ma-trix inequalities are transformed to standard LMIs. Furthermore, the optimalH∞ performances are pursued by solving optimization problems.

The rest sections of this paper are organized as follows: Section II addressesthe studied parabolic PDE systems and some lemmas which are necessary forthe results presented in this paper; Section III gives the static and dynamicstate feedback controllers with quantization, and provides the sufficient con-ditions for the finite-time H∞ controller design; Application to the catalyticrod in a reactor is explored to illustrate the feasibility and efficiency of thedesigned methods in Section IV; Section V draws some conclusions.

Notations: Rm×n, Rn, R+, and R represent the m × n dimensionalreal matrices, n-dimensional real vectors, positive real numbers, and all re-al numbers. Matrices X T and X−1 stand for the transpose and inverse ofX . Hn , L2([0, l];Rn) denotes a well defined Hilbert space, with ∥f(·)∥2 =√∫ l

0fT (s)f(s)ds, and f(s) : [0, l] → Rn is a vector function which is square

integrable. Matrix I with appropriate dimension means the identity matrix.A symmetric negative (positive, semipositive) definite matrix A is expressedas A < (>,≥)0. The minimum and maximum eigenvalues of a square matrixB are denoted by λmin(B) and λmax(B). The symmetry part of a matrix isreplaced with the symbol “∗”, e.g.,

[E + [F +G+ ∗] H

∗ J

],

[E + [F +G+ FT +GT ] H

HT J

].

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Title Suppressed Due to Excessive Length 5

2 Problem formulation and preliminaries

The mathematical model of nonlinear parabolic PDE systems with parametricuncertainties can be expressed as:

∂x(s, t)

∂t=

(A+∆A

)∂2x(s, t)

∂s2+ f(x(s, t))

+ (Bu +∆Bu)u(t) + (Bω +∆Bω)ω(t),

y(t) =

∫Ω

Cx(s, t)ds,

(1)

where x(·, t) , [x1(·, t) x2(·, t) · · · xn(·, t)]T ⊆ D is the state vector, the givenlocal domain which contains the equilibrium region x(·, t) = 0 is denoted asD , x(·, t) ∈ Hn|℘i,min ≤ xi(·, t) ≤ ℘i,max, i ∈ 1, 2, ..., n with known scalars℘i,min ≤ 0 and ℘i,max ≥ 0, s ∈ Ω = [0, l] ⊆ R+ and t ∈ R+ are the spatialposition and time variable, respectively. ω(t) is the external disturbance and is

assumed to satisfy∫Ω

∫ T0

ωT (t)ω(t)dtds ≤ ω with the finite time T and posi-tive scalar ω. A,Bu, Bω are constant matrixes. ∆A,∆Bu,∆Bω are parametricuncertainties caused by inaccurate modeling, poor design or manufacturing,or other external physical disturbances. In this study, the parametric uncer-tainties are assumed to satisfy [∆A ∆Bu ∆Bω] = M$[N1 N2 N3]. f(x(s, t)) isa nonlinear function which is sufficiently smooth, u(t) denotes the input, andy(t) is the measured output.

The following initial condition and boundary conditions are considered forthe system (1):

x(s, 0) = x0(s),

x(0, t) = x(l, t) = 0, t > 0.(2)

An assumption of function f(x(s, t)), the definition of finite-time stabliz-able, and some lemmas are used in this paper.

Assumption 1. For all x ∈ Rn = 0. Then an operator f : Rn → Rn issaid to be Lipschitz constraint if there is a scalar κ > 0 satisfying:

∥f(x(s, t))∥ ≤ κ∥x(s, t)∥. (3)

Definition 1. (Finite-time stabilizable) Given a positive definite matrix Rand three positive constants c1, c2, T , with c1 < c2, if there exists a controlleru(t) for system (1), ∀t ∈ [0, T ] such that:∫

Ω

xT (s, 0)Rx(s, 0)ds < c1 ⇒∫Ω

xT (s, t)Rx(s, t)ds < c2, (4)

then the closed-loop system (1) is said to be finite-time stabilizable with re-spect to (c1, c2, T ).

Page 6: Quantized State Feedback-Based H Control for Nonlinear

6 Teng-Fei Li et al.

Lemma 1. [43] If there is a well defined matrix 0 < ℑ ∈ Rn×n and avector function z(·) which is differentiable with z(0) = 0 or z(l) = 0, then:∫ l

0

zT (s)ℑz(s)ds ≥ π2

4l2

∫ l

0

zT (s)ℑz(s)ds. (5)

Lemma 2. [44] For real scalar t ∈ R+, vector function z : [0, t] → Rn, ifa well defined matrix F satisfy 0 < F ∈ Rn×n, then it can be derived that:

1

t

[ ∫ t

0

z(s)ds]T

F[ ∫ t

0

z(s)ds]≤

∫ t

0

zT (s)Fz(s)ds. (6)

Lemma 3.[45] If N + [ST + ∗] < 0 holds with appropriate dimensionsmatrices N,S and T, then for a given scalar ε, there exists a matrix U suchthat: [

N ∗εST + UT −ε[U+ ∗]

]< 0. (7)

Lemma 4.[45] For symmetric matrix M, real matrices X,Y with properdimensions, and ∆ satisfies ∆T∆ ≤ I, then:

M+ [X∆Y+ ∗] < 0 (8)

holds if and only if there is a positive scalar ϕ such that:

M+1

ϕXXT + ϕYTY < 0. (9)

The definition of quantizer q(t) is employed [46]. If there is real numbersH > 0 and ∆q > 0 that satisfying:

∥q(t)− t∥ ≤ ∆, if∥t∥ ≤ H,

∥q(t)∥ > H −∆, if∥t∥ > H,(10)

where the range and error bound of the quantizer are represented by H and∆q, respectively. And a kind of dynamic quantizer is considered as:

qµ(t) = µq(t

µ), (11)

with the dynamic parameter µ.

3 Main results

In the section, static/dynamic state feedback control with quantization for theparabolic PDE system (1) will be presented. Fig. 1 shows the diagram of statefeedback control strategy.

Page 7: Quantized State Feedback-Based H Control for Nonlinear

Title Suppressed Due to Excessive Length 7

!"#$!%%&$

'()"#*+&$

,-. tsx

!tu !"#$%&

'!()$%)

*+)",%-.(/!

0(/!%".+(1'2)"!3

45t

!"#$"%&'

Fig. 1 Block diagram of state feedback control strategy.

3.1 Static state feedback controller with quantization

The static state feedback controller with quantization is considered as:

u(t) =

∫Ω

Kqµ(x(s, t))ds, (12)

with the undetermined gain matrix K. By the definition of quantizer describedin (10) and (11), the above controller can be written as:

u(s, t) =

∫Ω

Kµ(s, t)q(x(s, t)µ(s, t)

)ds =

∫Ω

K[ϑ(s, t) + x(s, t)]ds, (13)

where ϑ(s, t) = µ(s, t)[q(

x(s,t)µ(s,t)

)− x(s,t)

µ(s,t)

].

By substituting the controller into (1) in the presence of parametric un-certainties ∆A,∆Bu,∆Bω, the quantized state feedback control system is de-rived:

∂x(s, t)

∂t=

(A+∆A

)∂2x(s, t)

∂s2+ f(x(s, t))

+ (Bu +∆Bu)K

∫Ω

[ϑ(s, t) + x(s, t)]ds

+ (Bω +∆Bω)ω(t),

y(t) =

∫Ω

Cx(s, t)ds.

(14)

The following theorem provides a sufficient design condi- tion for controller(12).

Theorem 1. For the state feedback system (14), if there exist matrixesP > 0, U and V with proper dimensions, scalars r1 > 0, r2 > 0, and ρ1 = ρur1such that the following conditions are fulfilled under the prescribed scalarγ > 0, quantizer’s range H and error ∆q, given positive matrix R and positiveconstants δ, c1, c2, T , with c1 < c2:[

P(A+∆A

)+ ∗

]> 0, (15)

Page 8: Quantized State Feedback-Based H Control for Nonlinear

8 Teng-Fei Li et al.

Π1 =

[Θ1 + ∗] + CTC

l 0 0 0 Θ1

∗ A1 P B1 0∗ ∗ −r2I 0 0

∗ ∗ ∗ −γ2

l I 0∗ ∗ ∗ ∗ −r1I

<0, (16)

c2 >λ2c1 + ω

λ1eδT , (17)

where Θ1 = 1l P (Bu+∆Bu)K, B1 = P

(Bω +∆Bω

), A1 = − π2

4l2 [P(A+∆A

)+

∗]+(r2κ2+

4r1l2∆2

qρ2u

M2 )I−δP , λ1 = λmin(R− 1

2PR− 12 ), λ2 = λmax(R

− 12PR− 1

2 ),and the dynamic parameter µ(s, t) is adjusted on-line as:

ρuH

∥x(s, t)∥ ≤ µ(s, t) ≤ 2ρuH

∥x(s, t)∥, (18)

where ρu ≥ 1. Then the quantized state feedback controller (12) subject to theadjusting rule (18), guarantees the prescribed H∞ performance γ for system(14) in the sense of finite-time stable with respect to (c1, c2, T ).

Proof. For the state feedback system (14), select the Lyapunov function as:

V (t) =

∫Ω

xT (s, t)Px(s, t)ds, (19)

where P is a positive matrix to be determined. By the time derivative of V (t),

V (t) =[ ∫

Ω

xT (s, t)P (A+∆A)d[∂x(s, t)

∂s

]+ ∗

]+[ ∫

Ω

xT (s, t)Pf(x(s, t))ds+ ∗]

+[ ∫

Ω

xT (s, t)dsP (Bu +∆Bu)K

∫Ω

ϑ(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)dsP (Bu +∆Bu)K

∫Ω

x(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)P(Bω +∆Bω

)ω(t)ds+ ∗

].

(20)

Integrating by part with the consideration of the boundary conditions (2)gives: ∫

Ω

xT (s, t)P (A+∆A)d[∂x(s, t)

∂s

]= xT (s, t)P (A+∆A)

∂x(s, t)

∂s|s=ls=0

−∫Ω

∂xT (s, t)

∂sP (A+∆A)

∂x(s, t)

∂sds

= −∫Ω

∂xT (s, t)

∂sP (A+∆A)

∂x(s, t)

∂sds.

(21)

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Title Suppressed Due to Excessive Length 9

Then, by (16) that[P (A + ∆A) + ∗

]> 0, with Lemma 1, substituting (21)

into (20), one can obtain:

V (t) ≤ − π2

4l2

∫Ω

xT (s, t)[P (A+∆A) + ∗

]x(s, t)ds

+[ ∫

Ω

xT (s, t)Pf(x(s, t))ds+ ∗]

+[ ∫

Ω

xT (s, t)P (Bu +∆Bu)Kds

∫Ω

ϑ(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)P (Bu +∆Bu)Kds

∫Ω

x(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)P (Bω +∆Bω)ω(t)ds+ ∗].

(22)

By the on-line adjusting rule (18), we have:

∥∥∥x(s, t)µ(s, t)

∥∥∥ ≤ H, (23)

according to (10),

∥∥∥q(x(s, t)µ(s, t)

)− x(s, t)

µ(s, t)

∥∥∥ < ∆q. (24)

Consider the homogeneity property of Euclidean norm to ϑ(s, t), we arrive at:

∥ϑ(s, t)∥ ≤ 2∆q

H∥x(s, t)∥. (25)

Let the Assumption 1 satisfied, then the following inequalities stand:

ϑT (s, t)ϑ(s, t) ≤4∆2

qρ2u

H2xT (s, t)x(s, t),

fT (x(s, t))f(x(s, t)) ≤ κ2xT (s, t)x(s, t).

(26)

By Lemma 2, it’s obvious that,∫Ω

ϑT (s, t)ds

∫Ω

ϑ(s, t)ds ≤ l

∫Ω

ϑT (s, t)ϑ(s, t)ds. (27)

By adding and subtracting:

r1l

∫Ω

ϑT (s, t)ds

∫Ω

ϑ(s, t)ds+ r2

∫Ω

fT (x(s, t))f(x(s, t))ds

Page 10: Quantized State Feedback-Based H Control for Nonlinear

10 Teng-Fei Li et al.

to the right side of (22),

V (t) ≤∫Ω

xT (s, t)A1x(s, t)ds

+

∫Ω

xT (s, t)ds[P (Bu +∆Bu)K + ∗]

l

∫Ω

x(s, t)ds

+[xT (s, t)Pf(x(s, t)) + ∗

]+[ ∫

Ω

xT (s, t)P (Bu +∆Bu)K

lds

∫Ω

ϑ(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)P (Bω +∆Bω)ω(t)ds+ ∗]

− r1

∫Ω

ϑT (s, t)ds

∫Ω

ϑ(s, t)ds− r2fT (x(s, t))f(x(s, t))

ds.

(28)

Consider the system (14) with H∞ performance index γ, and choose:

JT =

∫ T

0

∥y(t)∥2dt− γ2

∫ T

0

∥w(t)∥2dt. (29)

Combine (28) to (29) gives:

V (t)− δV (t) + ∥y(t)∥2 − γ2∥w(t)∥2 =

∫ T

0

∫ l

0

XT (s, t)Π1X(s, t)dsdt, (30)

where X(s, t)=[∫ΩxT (s, t)ds xT (s, t) fT (x(s, t)) ωT (t)

∫ΩϑT (t)ds]T .

By (16), we know that Π1 < 0, which means:

e−δt[V (t)− δV (t)] < e−δt[γ2∥w(t)∥2 − ∥y(t)∥2]. (31)

Then under the initial value condition, integrating (31) from 0 to T arrives:

0 < e−δT V (T )− V (0) <

∫ T

0

e−δt[γ2∥w(t)∥2 − ∥y(t)∥2]dt. (32)

Inequality (32) further gives:

∥y(t)∥2 < γ2∥w(t)∥2, (33)

and

V (T ) < eδT[V (0) +

∫ T

0

e−δt[γ2∥w(t)∥2dt]

< eδT[ ∫

Ω

xT (s, 0)Px(s, 0)ds+ ω]

= eδT[ ∫

Ω

xT (s, 0)R12 (R− 1

2PR− 12 )R

12x(s, 0)ds+ ω

]< eδT λ2

∫Ω

xT (s, 0)Rx(s, 0)ds+ eδT ω

< eδT λ2lc1 + eδT ω.

(34)

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Title Suppressed Due to Excessive Length 11

On the other hand,

V (T ) =

∫Ω

xT (s, T )Px(s, T )ds

=

∫Ω

xT (s, T )R12 (R− 1

2PR− 12 )R

12x(s, T )ds

> λ1

∫Ω

xT (s, T )Rx(s, T )ds.

(35)

Thus, ∫Ω

xT (s, t)Rx(s, t)ds <λ2c1 + ω

λ1eδT , ∀t ∈ [0, T ]. (36)

By (17), one can derive∫ΩxT (s, t)Rx(s, t)ds < c2.

Then, according to Definition 1, the prescribed H∞ performance in thefinite time interval [0, T ] for system (14) under the quantized state feedbackcontroller (12) could be obtained. This ends the proof.

Remark 1. To guarantee the prescribed H∞ performance for system (1),the terms which reflect the effect of quantization errors and uncertainties asΘ1,A1, and ∆Bω exist in Theorem 1. The quantization errors for the net-work system also appeared in [46]. Here, in Theorem 1, both the quantizationerrors and system uncertainties which may yield the deterioration of systemperformances and even system instability are considered.

Due to the uncertain terms ∆A,∆Bu,∆Bω and coupled terms PBuK,the conditions presented in Theorem 1 can not be applied directly to designthe quantized output controller (12). In order to cope with this problem, thefollowing method is provided to eliminate these terms, such that the finite-time H∞ control design conditions are given in terms of standard LMIs whichcan be solved by Matlab matrix toolbox.

Since [∆A ∆Bu ∆Bω] = M$[N1 N2 N3], then the matrix Π11 can berewritten as:

Π1 = Π2 + [Λ11$Λ12 + Λ21$Λ22 + Λ31$Λ32 + ∗], (37)

where

Π2 =

Θ2 +

CTCl 0 0 0 Θ2

∗ A2 P PBω 0∗ ∗ −r2I 0 0

∗ ∗ ∗ −γ2

l I 0∗ ∗ ∗ ∗ −r1I

,Λ11 =

[0 − π2

4l2 (PM)T 0 0 0]T

, Λ12 =[0 N1 0 0 0

],

Λ21 =[1l (PM)T 0 0 0 0

]T, Λ22 =

[N2K 0 0 0 N2K

],

Λ31 =[0 (PM)T 0 0 0

]T, Λ32 =

[0 0 0 N3 0

],

Θ2 = 1l [PBuK + ∗], A2 = − π2

4l2 [PA+ ∗] + (r2κ2 +

4r1l2∆2

qρ2u

H2 )I − δP .

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12 Teng-Fei Li et al.

By Lemma 4 and Schur complement, for εA, εu, εω > 0, (37) is equal to:

Π3 =

[Π2 [Λ11 εAΛ

T12 Λ21 εuΛ

T22 Λ31 εωΛ

T32]

∗ −diagεAI, εAI, εuI, εuI, εωI, εωI

]. (38)

Let K = U−1V , then the matrix (38) can be expressed as:

Π3 = Π4 + [Λ41ΥΛ42 + ∗], (39)

where

Π4 =

[Π2 [Λ11 εAΛ

T12 Λ21 0 Λ31 εωΛ

T32]

∗ −diagεAI, εAI, εuI, εuI, εωI, εωI

],

Π2=

[ 1lBuV + ∗] + CTC

l 0 0 0 Θ∗ A2 P PBω 0∗ ∗ −r2I 0 0

∗ ∗ ∗ −γ2

l I 0∗ ∗ ∗ ∗ −r1I

,Λ41=

[1l (PBu −BuU)T 0 0 0 0 0 0 0 εuN

T2 0 0

]T,

Λ42=[I 0 0 0 I 0 0 0 0 0 0

].

Since[P (A + ∆A) + ∗

]=[PA + ∗] + [PM$N1 + ∗], by Lemma 4, for a

positive scalar ε1, the following inequality stands:[−[PA+ ∗] + ε1N

T1 N1 PM

∗ −ε1I

]< 0. (40)

By using Lemma 3 and Schur complement to (39), if Π3 < 0, then thefollowing result can be derived:

Theorem 2. For the state feedback system (14), if there exist matrixesP > 0, U and V with proper dimensions, scalars r1, r2, εA, εu, εω, ε1 > 0, andρu1 = ρur1 such that the following conditions are fulfilled under the prescribedscalar γ > 0, quantizer’s range H and error ∆q with a given scalar εk, givenpositive matrix R and positive constants δ, c1, c2, T , with c1 < c2:[

−[PA+ ∗] + ε1NT1 N1 PM

∗ −ε1I

]< 0, (41)

Ω11 Ω12 Ω13 Ω14 Ω15 Ω16

∗ Ω22 0 0 Ω25 Ω26

∗ ∗ Ω33 0 0 0∗ ∗ ∗ Ω44 0 Ω46

∗ ∗ ∗ ∗ Ω55 0∗ ∗ ∗ ∗ ∗ Ω66

< 0, (42)

c2 >λ2c1 + ω

λ1eδT , (43)

whereΩ11 = diag1

l [BuV + ∗] + CTCl , r2κ

2I − π2

4l2 [PA+ ∗]− δP,

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Title Suppressed Due to Excessive Length 13

Ω12 =

[0 0 1

lBuVP PBω(s) 0

]T, Ω13 =

[0 0

− π2

4l2PM εAN1

],

Ω14 =

[1l PM 00 0

], Ω15 =

[0 0

PM 0

],

Ω16 = diag εkl [PBu −BuU ],

ρu1∆q

H , Ω22 = −diagr2I, γ2

l I, r1I,

Ω25 =

[0 0 00 εωN

T3 0

]T, Ω26 =

[0 0 V0 0 0

]T,

Ω33 = −diagεAI, εAI, Ω44 = −diagεuI, εuI,

Ω46 =

[0 0

εkεωNT2 0

], Ω55 = −diagεωI, εωI,

Ω66 = −diagεk[U+∗], r14l2 I, and the dynamic parameter µ(s, t) is adjust-

ed on-line as (18). Then the prescribed H∞ performance for system (14) underthe state feedback controller (12) with quantization could be obtained in thefinite-time internal [0, T ]. Moreover, the control gain is given by K = U−1V .

3.2 Dynamic state feedback controller with quantization

The dynamic state feedback controller with quantization is considered as:∂ϕ(s, t)

∂t= Adϕ(s, t) +Bdqµ(x(s, t)),

u(t) =

∫Ω

[Cdϕ(s, t) +Ddqµ(x(s, t))]ds,(44)

with the undetermined gain matrices Ad, Bd, Cd and Dd. By the definition ofquantizer described in (10) and (11), the above controller can be written as:

∂ϕ(s, t)

∂t= Adϕ(s, t) +Bd[(x(s, t)) + ϑ(s, t)],

u(t) =

∫Ω

Cdϕ(s, t) +Dd[x(s, t) + ϑ(s, t)]

ds.

(45)

By substituting the controller into (1), the quantized state feedback controlsystem is derived:

∂x(s, t)

∂t=

(A+∆A

)∂2x(s, t)

∂s2+ f(x(s, t))

+ (Bu +∆Bu)

∫Ω

Cdϕ(s, t)ds+ (Bω +∆Bω)ω(t)

+ (Bu +∆Bu)

∫Ω

Dd[x(s, t) + ϑ(s, t)]ds,

y(t) =

∫Ω

Cx(s, t)ds.

(46)

Assume that the initial state of the dynamic state feedback controller (44) iszero, i.e., ϕ(s, 0) = 0, then the following result provides the H∞ control designfor the closed-loop system (46) in the finite time interval [0, T ].

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14 Teng-Fei Li et al.

Theorem 3. For the dynamic state feedback system (46), if there ex-ist matrixes P1, P2 > 0, Ad, Bd, Cd and Dd with proper dimensions, scalarsr1, r2, r3, r4 > 0, such that the following conditions are fulfilled under the pre-scribed scalar γ > 0, quantizer’s range H and error ∆q, given positive matrixR, and positive constants δ, c1, c2, T , with c1 < c2:

[P1

(A+∆A

)+ ∗

]> 0, (47)

Ψ11 =

C1 0 0 0 D1 D1 0 0∗ E1 P1 [P2Bd]

T 0 0 F1 0∗ ∗ −r2I 0 0 0 0 0∗ ∗ ∗ W1 0 0 0 P2Bd

∗ ∗ ∗ ∗ −r1I 0 0 0∗ ∗ ∗ ∗ ∗ −r3I 0 0

∗ ∗ ∗ ∗ ∗ ∗ −γ2

l I 0∗ ∗ ∗ ∗ ∗ ∗ ∗ −r4I

< 0, (48)

c2 >λ2c1 + ω

λ1eδT , (49)

where C1 = [P1(Bu+∆Bu)Dd+∗]+CTCl , D1 = P1(Bu+∆Bu)Dd

l , E1 = − π2

4l2 [P1(A+

∆A) + ∗] + (r1l2 + r4)

4∆2qρ

2u

H2 I + r2κ2I − δP1, F1 = P1(Bω + ∆Bω), W1 =

[P2Ad + ∗] + r3l2I − δP2, λ1 = λmin(R

− 12P1R

− 12 ), λ2 = λmax(R

− 12P1R

− 12 ),

and the dynamic parameter µ(s, t) is adjusted on-line as (18). Then under thedynamic state feedback controller (44), closed-loop system (46) is finite-timestable with respect to (c1, c2, T ), and satisfies the H∞ performance with indexγ.

Proof. Select the following Lyapunov functional for the state feedback sys-tem (46):

V(t) =∫Ω

xT (s, t)P1x(s, t)ds+

∫Ω

ϕT (s, t)P2ϕ(s, t)ds, (50)

where P1, P2 > 0 are undetermined constant matrices. By (47) that[P1(A +

∆A) + ∗]> 0, the following relationship can be found according to (20) and

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Title Suppressed Due to Excessive Length 15

(21):

V(t) ≤ − π2

4l2

∫Ω

xT (s, t)[P1(A+∆A) + ∗

]x(s, t)ds

+[ ∫

Ω

xT (s, t)P1f(x(s, t))ds+ ∗]

+[ ∫

Ω

xT (s, t)P1(Bu +∆Bu)ds

∫Ω

Cdϕ(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)P1(Bu +∆Bu)ds

∫Ω

Ddx(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)P1(Bu +∆Bu)ds

∫Ω

Ddϑ(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)P1(Bω +∆Bω)ω(t)ds+ ∗]

+

∫Ω

ϕT (s, t)[P2Ad + ∗]ϕ(s, t)ds

+[ ∫

Ω

ϕT (s, t)P2Bdϑ(s, t)ds+

∫Ω

ϕT (s, t)P2Bdx(s, t)ds+ ∗].

(51)

Then with the properties of (26), by adding and subtracting:

r1l

∫Ω

ϑT (s, t)ϑ(s, t)ds+ r2

∫Ω

fT (x(s, t))f(x(s, t))ds

+ r3l

∫Ω

ϕT (s, t)ds

∫Ω

ϕ(s, t)ds+ r4

∫Ω

ϑT (s, t)ϑ(s, t)ds

(52)

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16 Teng-Fei Li et al.

to the right side of (51), gives:

V(t) ≤∫Ω

xT (s, t)E1x(s, t)ds+

[xT (s, t)P1f(x(s, t)) + ∗

]+[ ∫

Ω

xT (s, t)P1f(x(s, t))ds+ ∗]

+[ ∫

Ω

xT (s, t)dsP1(Bu +∆Bu)Cd

∫Ω

ϕ(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)dsP1(Bu +∆Bu)Dd

∫Ω

x(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)dsP1(Bu +∆Bu)Dd

∫Ω

ϑ(s, t)ds+ ∗]

+[ ∫

Ω

xT (s, t)P1(Bω +∆Bω)ω(t)ds+ ∗]

+

∫Ω

ϕT (s, t)[P2Ad + ∗]ϕ(s, t)ds+[ ∫

Ω

ϕT (s, t)P2Bdϑ(s, t)ds+ ∗]

+[ ∫

Ω

ϕT (s, t)P2Bdx(s, t)ds+ ∗]− r1l

∫Ω

ϑT (s, t)ϑ(s, t)ds

− r2

∫Ω

fT (x(s, t))f(x(s, t))ds− r3l

∫Ω

ϕT (s, t)ds

∫Ω

ϕ(s, t)ds

− r4

∫Ω

ϑT (s, t)ϑ(s, t)dsds.

(53)

Consider the system (46) with H∞ performance index γ as (29), Combine (28)to (29) gives:

V(t)− δV(t) + ∥y(t)∥2 − γ2∥w(t)∥2 =

∫ T

0

∫ l

0

XT (s, t)Ψ11X(s, t)dsdt, (54)

where X(s, t)=[∫ΩxT (s, t)ds xT (s, t) fT (x(s, t)) ϕT (s, t)

∫ΩϑT (s, t)ds∫

ΩϕT (s, t)ds ω(t) ϑ(s, t)]T .By (48) that Ψ11 < 0, which means:

e−δt[V(t)− δV(t)] < e−δt[γ2∥w(t)∥2 − ∥y(t)∥2]. (55)

Then under the initial value condition, integrating (55) from 0 to T arrives:

0 < e−δT V(T )− V(0) <∫ T

0

e−δt[γ2∥w(t)∥2 − ∥y(t)∥2]dt. (56)

Since the initial state of the controller (44) is zero, the inequality (56) furthermeans:

∥y(t)∥2 < γ2∥w(t)∥2, (57)

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Title Suppressed Due to Excessive Length 17

and

V(T ) < eδT[V(0) +

∫ T

0

e−δt[γ2∥w(t)∥2dt]

< eδT[ ∫

Ω

xT (s, 0)Px(s, 0)ds+

∫Ω

ϕT (s, 0)Pϕ(s, 0)ds+ ω]

< eδT[ ∫

Ω

xT (s, 0)R12 (R− 1

2PR− 12 )R

12x(s, 0)ds+ ω

]< eδT λ2

∫Ω

xT (s, 0)Rx(s, 0)ds+ eδT ω

< eδT λ2lc1 + eδT ω.

(58)

On the other hand,

V(T ) =

∫Ω

xT (s, T )P1x(s, T )ds+

∫Ω

ϕT (s, T )P2ϕ(s, T )ds

>

∫Ω

xT (s, T )R12 (R− 1

2P1R− 1

2 )R12x(s, T )ds

> λ1

∫Ω

xT (s, T )Rx(s, T )ds.

(59)

Thus, ∫Ω

xT (s, t)Rx(s, t)ds <λ2c1 + ω

λ1eδT , ∀t ∈ [0, T ]. (60)

By (49), one can derive∫ΩxT (s, t)Rx(s, t)ds < c2.

Then, according to Definition 1, the system (46) under the dynamic statefeedback controller (44) with quantization is finite-time stable in the interval[0, T ], and the prescribed H∞ performance could be satisfied. This ends theproof.

Since [∆A ∆Bu ∆Bω] = M$[N1 N2 N3], similar to the proof of Theorem2, the following theorem provides conditions in term of standard LMIs.

Theorem 4. If there exist matrixes P1, P2 > 0, P2A, P2B , Ad, Bd, U1,U2, V1 and V2 with proper dimensions, scalars ε∆, ε1, r1, r2, r3, r4 > 0, andρur = ρu(r1l

2 + r4) such that the following conditions are fulfilled under theprescribed scalar γ > 0, quantizer’s range H and error∆q with a given positivematrix R and positive constants εk, δ, c1, c2, T , with c1 < c2:[

−[P1A+ ∗] + ε1NT1 N1 P1M

∗ −ε1I

]< 0, (61)

Ω11 Ω12 Ω13 Ω14 Ω15 Ω16 Ω17

∗ Ω22 0 Ω24 0 0 0∗ ∗ Ω33 0 0 0 Ω37

∗ ∗ ∗ Ω44 0 Ω46 0∗ ∗ ∗ ∗ Ω55 0 0∗ ∗ ∗ ∗ ∗ Ω66 Ω67

∗ ∗ ∗ ∗ ∗ ∗ Ω77

< 0, (62)

Page 18: Quantized State Feedback-Based H Control for Nonlinear

18 Teng-Fei Li et al.

c2 >λ2c1 + ω

λ1eδT , (63)

where

Ω11 = diag [BuV2+∗]+CTCl ,− π2

4l2 [P1A+ ∗] + r2κ2I − δP1,

Ω12 =

[0 0P1 PT

2B

], Ω13 =

[BuV2

lBuV1

l0 0

], Ω14 =

[0 0

P1Bω 0

],

Ω15 = diagP1Ml , P1M, Ω16 =

[0 0

0 − π2

4l2NT1

],

Ω17=

[εkl [P1Bu −BuU2] + V T

2εk[P1Bu−BuU1]

l∆qρur

H0 0 0

],

Ω22 = −diagr2I, [P2A + ∗] + r3l2I − δP2, Ω24 = −diag0, P2B,

Ω33 = −diagr1I, r3I, Ω37 =

[V T2 0 00 V T

1 0

], Ω44 = −diagγ2

l I, r4I,

Ω46 =

[0 NT

3

0 0

], Ω55 = −diagε∆I, ε∆I, Ω66 = −diagε∆I, ε∆I,

Ω67 =

[εkε∆N2 εkε∆N2 0

0 0 0

], Ω77 = −diagεk[U2+∗], εk[U1+∗], r1l

2+r44 I,

and the dynamic parameter µ(s, t) is adjusted on-line as (18), then the closed-loop system (46) is finite-time stable, and the prescribed H∞ performanceof (29) with index γ could be obtained under the dynamic state feedbackcontroller (44). Moreover, the control gain matrices are given by Ad = P2AP

−12 ,

Bd = P2BP−12 , Cd = U−1

1 V1, Dd = U−12 V2.

Remark 2. The conditions in Theorem 2 are standard LMIs which can besolved by Matlab LMI toolbox. Thus, the controllers can be frequently derivedby solving (41)-(42) in Theorem 2 and (61)-(62) in Theorem 4. To obtain thebest robust control effect, the following optimization problem is employed:

min γ2,

subject to LMIs in Thorem 2 (or Theorem 4).(64)

Remark 3. When the candidate parameters ε1, εA, εu, εω, εk and r2 intheorems are associated with the spatial variable s, then the results also standand the conditions could be relaxed.

Remark 4. If the Dirichlet boundary conditions (2) are replaced with the

mixed boundary conditions x(s, t)|s=0 = ∂x(s,t)∂s |s=l = 0, Theorem 1-4 can also

be derived. Moreover, when the system structure Bω and uncertain parameter∆Bω are related to spatial variable, all the results proposed in this paper alsostand with parameters Bω(s) and N3(s).

Remark 5. In this paper, the dynamic parameter µ(s, t) which is trans-mitted to the system are adjusting by the rule presented in [46].

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Title Suppressed Due to Excessive Length 19

A B

A BA

Fig. 2 Catalytic rod in a reactor.

The adjusting rule:

µ(s, t) =

floor

(2ρuH

|x(s, t)| × 10ℓ)× 10−ℓ, 0 ≤ 2ρu

H|x(s, t)| < 1

2,

1,1

2≤ ρu

H|x(s, t)| < 1,

f loor(ρuH

|x(s, t)|), 1 <

ρuH

|x(s, t)|,

(65)

where ℓ = minℓ ∈ N+| 2ρu

H |x(s, t)| × 10ℓ > 1 and the function floor(ζ)denotes the largest integer of ζ, but less than ζ.

4 Application to catalytic rod in a reactor

Consider a furnace which is filled with specie A and a catalytic reaction ofthe form A → B takes place on a long thin rod shown in Fig. 2. This rodacts as a cooling medium since the reaction in the furnace is exothermic. Theprocess model of temperature on the rod which is also studied in [47] can beillustrated by:

∂T (s, t)

∂t= (A+∆A)

∂2T (s, t)

∂s2+ β1(e

− α1+T (s,t) − e−α)

− β2T (s, t) + (Bu +∆Bu)u(t) + (Bω +∆Bω)ω(t),

y(t) =

∫ l

0

CT (s, t)ds,

(66)

where T (s, t) ∈ R is the dimensionless temperature of the catalytic rod, β1

is the heat in the reaction, α represents the activation energy, β2 denotes thetransfer coefficient of heat, y(t) ∈ R denotes the measured output, u(t) andω(t) denote the control input and the related disturbance. Bu is the distribu-tion matrix of control actuators, Bω is a known constant matrix, and C is thematrix of the point sensor. l = 2 is the length of the catalytic rod.

For simulation purposes, the initial temperature and the surface tempera-ture of the battery are assumed to be relative level, which means the following

Page 20: Quantized State Feedback-Based H Control for Nonlinear

20 Teng-Fei Li et al.

conditions are meeted:

T (s, t)|s=0 = T (s, t)|s=l = 0, t > 0,

T0(s) = 0.2 sin(πs).(67)

Here, the coefficients are given by:

A = 1.0, Bu = 22.7975, Bω = 16.3175, β1 = 6.5, β2 = 1.3, α = 2.0. (68)

The parametric uncertainties ∆A1,∆Bu and ∆Bω are assumed to be:

[∆A ∆Bu ∆Bω] = M$[N1 N2 N3], (69)

where M = 0.5406, $ = 0.5, N1 = 0.0101, N2 = −0.1569, N3 = 0.2778. Thenthe state of open-loop system (67) can be obtained and shown in Fig. 3 withthe disturbance ω(t) = 0.3e−0.2t+e−0.2t cos(2πt)+e−0.2t sin(3πt) and ω = 7.5.By the simulation results, the Assumption 1 can be fulfilled with κ = 0.55. Setthe range H = 100 and error ∆ = 0.1 of the quantizer. And give the matrixand scalars as R = I, εk = 2.5, c1 = 0.4, c2 = 150, T = 20, and δ = 0.001:

1) By solving the static control design conditions presented in Theorem2, the variable of optimal H∞ performance γ = 0.6006, the gain of the con-troller K = −8.5980, the adjusting parameter ρu = 1.0001, and the otherused parameters r1 = 0.0276, r2 = 1.4692 × 10−4, εA = 0.0027, εu = 0.0021,εω = 0.0213, ε1 = 0.7922 can be found by solving the optimization problem(64). The state profile of closed-loop system under static state feedback control(12) is depicted in Fig. 4.

2) By solving the dynamic control design conditions presented in Theorem4, the variable of optimal H∞ performance γ = 7.7378, the gain parameters ofthe controller Ad = −8.5980, Bd = 7.3277× 10−11, Cd = −3.2142× 104, Dd =−2.4922, the adjusting parameter ρu = 1.0982, and the other used parametersr1 = 0.2371, r2 = 0.0139, r3 = 8.2321 × 107, r4 = 0.3647, ε1 = 75.1742,ε∆ = 0.1245 can be found by solving the optimization problem (64). Fig.5 shows the state profile of closed-loop system under dynamic state feedbackcontrol (44). The difference e(s, t) between the state of the system under staticand dynamic state feedback is depicted in Fig. 6.

The simulations of static state feedback controller and dynamic state feed-back controller are described in Fig. 7 with blue dashed line and green dashedline respectively, and the red line denotes the difference between the staticand dynamic controller. The evolution of the norm ∥x(s, t)∥2 under the staticcontroller and the dynamic controller are depicted in Fig. 8.

Through simulation results presented above, it is obviously that the designmethods for the nonlinear parabolic PDE systems with parametric uncertain-ties can guarantee the prescribed H∞ performance in the finite-time intervalt ∈ [0, 20].

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Title Suppressed Due to Excessive Length 21

Fig. 3 Open-loop state profile of system (67).

Fig. 4 Close-loop state profile of system (67) with controller (12).

Fig. 5 Close-loop state profile of system (67) with controller (44).

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22 Teng-Fei Li et al.

Fig. 6 Difference between the static and dynamic lose-loop state profile of system (67).

0 2 4 6 8 10 12 14 16 18 20−1.5

−1

−0.5

0

0.5

1

1.5

t

u

0 0.05 0.1 0.15 0.2

−1

−0.5

0

static controller

dynamic controller

difference

Fig. 7 Quantized state feedback controller (12) and (44).

0 2 4 6 8 10 12 14 16 18 200

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

t

‖x(s,t)‖ 2

under static controllerunder dynamic controller

Fig. 8 ∥x(s, t)2∥ under the the controller (12) and (44).

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Title Suppressed Due to Excessive Length 23

Comparative Explanations: The developed quantized state feedbackcontrol design strategies in this paper provide efficient methods for the finite-time H∞ control of the nonlinear parabolic PDE system with parametric un-certainties. Compared with the existing results, some innovations and advan-tages of the presented feedback control strategies could be identified in thefollowing aspects:

1) Different from [7–10,13–15], the system state information is consideredto be transmitted via the digital communication channel which is used fre-quently in the sensor side. Then static state feedback controller is studied forthe parameter uncertain nonlinear parabolic PDE system via finite-time in-terval. And quantized dynamic state feedback controller is also investigated,which has not been studied yet in the existing literatures. In addition, by thepresented simulation results, it can be observed that the static state feedbackcontroller (12) has a better control effect and a lower optimal index of H∞performance compared with the dynamic one (44).

2) In comparison with [22,23,41,42], a kind of dynamic quantizer which isregarded to be more general and more advantageous than that of a static onefor the control input signal is adopted in this paper.

3) Compared with [9,13], new finite-time H∞ control design conditionsfor nonlinear parabolic PDE system under the static and dynamic state feed-back controllers are provided in terms of LMIs. And the H∞ performances isoptimized by solving the optimization problems subject to the LMIs.

5 Conclusion

This paper has studied the finite-time H∞ control problem of parametric un-certain nonlinear parabolic PDE systems via static/dynamic state feedback.Considering that the system state information is transmitted through digitalcommunication channel, a dynamic quantizer is adopted to deal with the limit-ed capability of the communication channel. Moreover, the quantization errorsgenerated by the quantizer are well treated. And finite-time stability condi-tions of the existence of the designed controllers and adjusting parametersare presented in terms of nonlinear matrix inequalities by constructing appro-priate Lyapunov functionals. Then standard LMIs are derived by using someinequalities and decomposition technic. In addition, the H∞ performances canbe optimized by solving optimization problems subject to these standard LMIs.At last, an exploration to a catalytic rod in a reactor is presented to verify theeffectiveness of the proposed strategies. In the following research, under theeffect of quantization and actuator faults, the control problem for nonlinearparabolic PDE systems with space-varying parametric uncertainties, and thestabilization problem for nonlinear PDE systems with time-varying delays willbe investigated.

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24 Teng-Fei Li et al.

Conflict of interest

The authors declare that they have no conflict of interest.

Data availability

The datasets generated during and/or analysed during the current study areavailable from the corresponding author on reasonable request.

References

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