Interval error observer-based aircraft engine active fault tolerant control method

Patent metadata

Field	Value
Publication number	US-11635734-B2
Application number	US-201916609940-A
Country	US
Kind code	B2
Filing date	Jan 10, 2019
Priority date	Jan 10, 2019
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

Abstract

The present invention provides an interval error observer-based aircraft engine active fault tolerant control method, and belongs to the technical field of aircraft control. The method comprises: tracking the state and the output of a reference model of an aircraft engine through an error feedback controller; compensating a control system of the aircraft engine having a disturbance signal and actuator and sensor faults through a virtual sensor and a virtual actuator; observing an error between a system with fault of the aircraft engine and the reference model through an interval error observer, and feeding back the error to the error feedback controller; and finally, using a difference between the output of the reference model of the system with fault and the output of the virtual actuator as a control signal to realize active fault tolerant control of the aircraft engine.

First claim

The invention claimed is:

1. An interval error observer-based aircraft engine active fault tolerant control method for a controller of an aircraft engine, comprising the following steps:
step 1.1: establishing an affine parameter-dependent aircraft engine linear-parameter-varying LPV model
{dot over (x)} p ( t )=[ A 0 +ΔA (θ)] x p ( t )+[ B 0 +ΔB (θ)] u p ( t )+ d f ( t )

y p ( t )= C p x p ( t )+ v ( t )  (1)

where R m and R m×n respectively represent a m-dimensional real number column vector and a m-row n-column real matrix; state vectors x p =[Y nl Y nh ] T ∈ R n x , Y nl and Y nh respectively represent variation of relative conversion speed of low pressure and high pressure rotors; n x represents the dimension of a state variable x; n y represents the dimension of an output vector y; n u represents the dimension of control input u p ; control input u p =U p f ∈ R n x is a fuel pressure step signal; output vectors y p =Y nh ∈ R n y , A 0 ∈ R n x ×n x , B 0 ∈ R n x ×n x and C p ∈ R n y ×n x are known system constant matrices; d f (t) is a disturbance variable; the relative conversion speed n h of the high pressure rotor of the aircraft engine is a scheduling parameter θ ∈ R p ; system variable matrices ΔA(θ) and ΔB(θ) satisfy − ΔA ≤ΔA(θ)≤ ΔA and − ΔB ≤ΔB(θ)≤ ΔB ; ΔA ∈ R n x ×n x is an upper bound of ΔA(θ); ΔB ∈ R n x ×n u is an upper bound of ΔB(θ); ΔA ≥0, ΔB ≥0; a state variable initial value x p (0) satisfies x 0 ≤x p (0)≤ x 0 ; x 0 , x 0 ∈ R n x are respectively known upper bound and lower bound of the state variable initial value x p (0); d , d ∈ R n x are known upper bound and lower bound of an unknown disturbance d f (t); sensor noise v(t) satisfies |v(t)|<V; V is a known bound; V>0;
step 1.2: defining reference model of fault-free system of the aircraft engine (1) as
{dot over (x)} pref ( t )= A 0 x pref ( t )+ B 0 u pref ( t )
y pref ( t )= C p x pref ( t )  (2)

where x pref ∈ R n x is a reference state vector of the fault-free system; u pref ∈ R n x is control input of the fault-free system; y pref ∈ R n y is a reference output vector; an error feedback controller of the fault-free system of the aircraft engine is designed according to the aircraft engine LPV model established in the step 1.1;
step 1.2.1: defining an error e p (t)=x pref (t)−x p (t) between the affine parameter-dependent aircraft engine LPV model and the reference model of the fault-free system of the aircraft engine to obtain error state equations of the fault-free system:
ė p ( t )=[ A 0 +ΔA (θ)] e p ( t )+[ B 0 +ΔB (θ)]Δ u cp ( t )−Δ A (θ) x pref ( t )−Δ B (θ) u pref ( t )− d f ( t )

ε cp ( t )= C p e p ( t )− v ( t )  (3)

where Δu cp (t) and ε cp (t) represent the input and output difference between the reference model and aircraft engine LPV model with Δu cp (t)=u pref (t)−u p (t) and ε cp (t)=y pref (t)−y p (t), respectively;
step 1.2.2: representing state equations of the upper bound ē p and the lower bound e p of the error vector e p as:
{dot over ( ē )} p ( t )=[ A 0 −LC p ] ē p ( t )+[ B 0 + Δ B ]Δ u cp ( t )+ Lε cp ( t )+| L|V− d ( t )+ Δ A | x pref ( t )|+ϕ p ( t )

{dot over ( e )} p ( t )=[ A 0 −LC p ] e p ( t )+[ B 0 − Δ B ]Δ u cp ( t )+ Lε cp ( t )−| L|V− d ( t )− Δ A | x pref ( t )|−ϕ p ( t )  (4)

where ē p , e p ∈ R n x are respectively the upper bound and the lower bound of the error vector e p , i.e., e p (t)≤e p (t)≤ē p (t); ϕ p (t)= ΔA (ē p + (t)+ e p − (t)), ē p + =max {0, ē p }, ē p − =ē p + −ē p , e P + =max {0, ē p }, e p − = e p + −e p ; L ∈ R n x ×n y is an error gain matrix of the fault-free system and satisfies A 0 −LC p ∈ M n x ×n x ; M n x represents a set of n x -dimensional Metzler matrix; |L| represents taking absolute values of all elements of the matrix L;
step 1.2.3: respectively setting e pa =0.5(ē p + e p ) and e pd =ē p − e p , which represent the middle value and range of the interval of e p , respectively; rewriting the formula (4) as:
ė pd ( t )=[ A 0 −LC p ] e pd ( t )+2 Δ B Δ u cp ( t )+ϕ pd ( t )+δ pd ( t )

ė pa ( t )=[ A 0 −LC p ] e pa ( t )+ B 0 Δu cp ( t )+ LC p e p ( t )+δ pa ( t )  (5)

where ϕ pd (t), δ pa (t) and δ pd (t) are variables defined as
ϕ pd ( t )=2 Δ A ( ē p − ( t )+ e p − ( t ))

δ pd ( t )=2| L|V− d ( t )+ d ( t )+2Δ A|x pref ( t )|

δ pa ( t )=− Lv ( t )−0.5( d ( t )+ d ( t ))  (6)

step 1.2.4: defining output signal of the error feedback controller as:
Δ u cp ( t )= K a e pa ( t )+ K d e pd ( t )  (7)

where K d , K a ∈ R n x ×n x represent gain matrices of the error feedback controller signal (7); setting e x (t)=e p (t)−e pa (t), −0.5e pd (t)≤e x (t)≤0.5e pd (t), and then
ė pa ( t )=[ A 0 +B 0 K a ] e pa ( t )+ B 0 K d e pd ( t )+ LC p e x ( t )+δ pa ( t )  (8)

step 1.2.5: rewriting formulas (5) and (8) as:

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Assignees

• Univ Dalian Tech

Inventors

• Ma Yanhua
• Du Xian
• Wang Ye
• Wang Rui
• Sun Ximing

Classifications

• G05D1/101

  specially adapted for aircraft · CPC title

• F02C9/00

  Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants (controlling air intakes F02C7/057; controlling turbines F01D; controlling compressors F04D27/00; controlling in general G05) · CPC title

• G05B23/0289 Primary

  Reconfiguration to prevent failure, e.g. usually as a reaction to incipient failure detection · CPC title

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title

• G05B13/042 Primary

  in which a parameter or coefficient is automatically adjusted to optimise the performance · CPC title