METHOD FOR DETECTING A PHYSICAL STATUS OF A FLEXIBLE STRUCTURE

Abstract

A method in the field of flight control laws (CLAWs) used to control a flexible structure, for example an air to air refueling flying boom system, the method detecting the physical status determined by exogenous boundary conditions acting on the flexible structure. A computer program is provided which carries out the method for detecting the physical status of a flexible structure. A system and aircraft comprising such a flexible structure are also provided.

Claims

1. A method for detecting a physical status of a flexible structure, said status being either free-movement or restricted-movement, the flexible structure having time-varying elastic characteristics, with a total number N∈.sup.+ of elastic modes, being i a generic elastic mode, i∈.sup.+:i∈[1, N], and the flexible structure being controlled by flight control laws (CLAWs), these CLAWs comprising specific filtering modes for free-movement or restricted-movement status, the method comprising the following steps: a) sampling a first and a second discrete-time scalar signal y.sup.A and y.sup.B containing measured dynamics of the flexible structure, being y.sub.n.sup.A and y.sub.n.sup.B an n.sup.th sample of the respective signal provided by a first (A) and second (B) active measurement source, this sampling being performed with a sample time Δt, and the n.sup.th sample of a signal being n∈.sup.+:n∈[1, ∞), b) obtaining from the first and second y.sub.n.sup.A and y.sub.n.sup.B sampled signals the following signals: first elastic mode (i=1) estimated activity signal {circumflex over (γ)}.sub.n.sup.F in free-movement status, first elastic mode (i=1) estimated activity signal γ.sub.n.sup.1.sup.R in restricted-movement status, c) obtaining the estimated isolated free-movement and restricted-movement first elastic mode excitation signals, ε.sub.n.sup.1.sup.F and ε.sub.n.sup.1.sup.R respectively from the signals γ.sub.n.sup.1.sup.F and γ.sub.n.sup.1.sup.R, by means of a first and second notch filters, where {circumflex over (ε)}.sub.n.sup.1.sup.F and {circumflex over (ε)}.sub.n.sup.1.sup.R are:
{circumflex over (ε)}.sub.n.sup.1.sup.F=NF.sub.F{circumflex over (γ)}.sub.n.sup.1.sup.F,
{circumflex over (ε)}.sub.n.sup.1.sup.R=NF.sub.R{circumflex over (γ)}.sub.n.sup.1.sup.R, wherein NF.sub.F and NF.sub.R denote discrete transfer functions of notch-filters, d) estimating an amplitude ∥{circumflex over (ε)}.sub.n.sup.1.sup.F∥ and ∥{circumflex over (ε)}.sub.n.sup.1.sup.R∥ of the isolated elastic mode excitation signals {circumflex over (ε)}.sub.n.sup.1.sup.F and {circumflex over (ε)}.sub.n.sup.1.sup.R by amplitude demodulation, e) recursively computing an estimated probability P.sub.n.sup.R of the flexible structure to be in a restricted-movement status, wherein P.sub.n.sup.R∈∈[0, 1] and is defined as:
P.sub.n.sup.R=max(0,min(1,P.sub.n-1.sup.R+(λ.Math.U.sub.n))), wherein λ is an update gain constant being λ>0, and P.sub.n-1.sup.R is a previous value of the estimated probability of the flexible structure in a restricted-movement status at the (n−1).sup.th sample, wherein when n=1; then P.sub.n-1.sup.R=0, being the step e) of the method applied for a first time, wherein U.sub.n is defined as follows:
U.sub.n=(∥{circumflex over (ε)}.sub.n.sup.1.sup.F∥−∥{circumflex over (ε)}.sub.n.sup.1.sup.R∥).sup.2P.sub.n-1.sup.R−∥{circumflex over (ε)}.sup.1.sup.R∥(∥{circumflex over (ε)}.sub.n.sup.1.sup.F∥−∥{circumflex over (ε)}.sub.n.sup.1.sup.R), f) detecting the physical status of the flexible structure by recursively computing a discrete state Boolean signal R.sub.n at the n.sup.th sample, wherein R.sub.n-1 is a previous value of the discrete state Boolean signal at the (n−1).sup.th sample, wherein when n=1, being step f) of the method applied for the first time, then R.sub.n-1=false, being the flexible structure in free-movement status, and the discrete state Boolean signal R.sub.n being recursively computed as follows: if P.sub.n.sup.R≥p.sub.R and R.sub.n-1=false, then R.sub.n=true being the flexible structure in the restricted-movement status, otherwise R.sub.n=false or if P.sub.n.sup.R≤p.sub.R and R.sub.n-1=true, then R.sub.n=false being the flexible structure in the free-movement status, otherwise R.sub.n=true, wherein 0≤p.sub.R≤1 corresponds to a predetermined restricted-movement probability parameter, and 0≤p.sub.F≤1 corresponds to a predetermined free-movement probability parameter, and wherein the detected physical status of the flexible structure corresponds to free-movement status if R.sub.n=false, and to restricted-movement status if R.sub.n=true.

2. The method according to claim 1, wherein the filtering mode of the flight control laws (CLAWs) is set by means of a binary discrete input signal M, being M.sub.n an n.sup.th sample of the M signal defined as: M.sub.n=0 sets the filtering mode to free-movement filtering mode, or M.sub.n=1 sets the filtering mode to restricted-movement filtering mode.

3. The method according to claim 2 further comprising the step g) of updating the filtering mode already set as follows: if R.sub.n=true, the filtering mode is switched to the restricted-movement filtering mode by setting the n.sup.th sample of the input signal M.sub.n to one (M.sub.n=1), if R.sub.n=false, the filtering mode is switched to the free-movement filtering mode by setting the n.sup.th sample of the input signal M.sub.n to zero (M.sub.n=0).

4. The method according to claim 1, wherein the first and second notch-filters NF.sub.F and NF.sub.R present in step c) are parametric notch-filters applied to signals {circumflex over (γ)}.sub.n.sup.1.sup.F and γ.sub.n.sup.1.sup.R with respective notch-frequencies coincident with frequencies {circumflex over (ω)}.sub.n.sup.1.sup.R and {circumflex over (ω)}.sub.n.sup.1.sup.F at the n.sup.th sample, wherein the parametric transfer functions of these notch-filters in a z.sup.−1 plane are:
NF.sub.F=NF(z.sup.−1;{circumflex over (ω)}.sub.n.sup.1.sup.R),
NF.sub.R=NF(z.sup.−1;{circumflex over (ω)}.sub.n.sup.1.sup.F), wherein NF denotes the discrete transfer function of the parametric first and second notch-filters in the z.sup.−1 plane.

5. The method according to claim 1, wherein the amplitude demodulation of step d) is performed with a third parametric notch-filter applied to the signal {circumflex over (ε)}.sub.n.sup.1.sup.F with a notch frequency of 2{circumflex over (ω)}.sub.n.sup.1.sup.F and a fourth parametric notch-filter applied to the signal {circumflex over (ε)}.sub.n.sup.1.sup.R with a notch frequency of 2ω.sub.n.sup.1.sup.R, wherein the estimated amplitudes are computed as:
∥{circumflex over (ε)}.sub.n.sup.1.sup.F∥=√{square root over (2({circumflex over (ε)}.sub.n.sup.1.sup.F).sup.2NF(z.sup.−1;2{circumflex over (ω)}.sub.n.sup.1.sup.F))},
∥{circumflex over (ε)}.sub.n.sup.1.sup.R∥=√{square root over (2({circumflex over (ε)}.sub.n.sup.1.sup.R).sup.2NF(z.sup.−1;2{circumflex over (ω)}.sub.n.sup.1.sup.R))}, wherein NF is the discrete transfer function of the parametric third and fourth notch-filters in a z.sup.−1 plane.

6. The method according to claim 1, wherein the restricted-movement and free-movement probability parameters p.sup.R and p.sup.F of step f) are p.sup.Rϵ[0.75, 0.95] and p.sup.Fϵ[0.05, 0.25].

7. The method according to claim 1, wherein step a) further comprises sampling a third discrete-time scalar signal L containing a measured shape of the flexible structure, being L.sub.n the n.sup.th sample of the L signal provided by a third active measurement source (C), this sampling being performed with a sample time Δt, and the n.sup.th sample of a signal being n∈.sup.+:n∈[1, ∞).

8. The method according to claim 4, wherein the n.sup.th sample of the estimated first elastic mode (i=1) activity signal {circumflex over (γ)}.sub.n.sup.1.sup.F in free-movement status and the n.sup.th sample of the estimated first elastic mode (i=1) activity signal {circumflex over (γ)}.sub.n.sup.1.sup.R in restricted-movement status obtained in step b) fulfill:
{circumflex over (γ)}.sub.n.sup.1.sup.F=BP(z.sup.−1;{circumflex over (ω)}.sub.n.sup.1.sup.F)(1−{circumflex over (K)}.sub.n.sup.1.sup.F)(y.sub.n.sup.A−y.sub.n.sup.B),
{circumflex over (γ)}.sub.n.sup.1.sup.R=BP(z.sup.−1;{circumflex over (ω)}.sub.n.sup.1.sup.R)(1−{circumflex over (K)}.sub.n.sup.1.sup.R)(y.sub.n.sup.A−y.sub.n.sup.B), being BP is a discrete transfer function of a band-pass filter with a parametric band-pass frequency, and {circumflex over (K)}.sub.n.sup.1.sup.F and {circumflex over (K)}.sub.n.sup.1.sup.R denoting estimated perfect cancellation parameters of the first elastic mode (i=1) in free-movement and restricted-movement status respectively.

9. The method according to claim 4, wherein step a) further comprises sampling a third discrete-time scalar signal L containing a measured shape of the flexible structure, being L.sub.n the n.sup.th sample of the L signal provided by a third active measurement source (C), this sampling being performed with a sample time Δt, and the n.sup.th sample of a signal being n∈.sup.+:n∈[1, ∞), wherein the notch-frequencies at the n.sup.th sample, correspondent with the free-movement and restricted-movement status, {circumflex over (ω)}.sub.n.sup.1.sup.F and {circumflex over (ω)}.sub.n.sup.1.sup.R, are obtained by computing mapping functions:
{circumflex over (ω)}.sub.n.sup.1.sup.F={circumflex over (ω)}.sup.1.sup.F(L.sub.n),
{circumflex over (ω)}.sub.n.sup.1.sup.R={circumflex over (ω)}.sup.1.sup.R(L.sub.n); wherein, the mapping functions {circumflex over (ω)}.sup.1.sup.F(L.sub.n) and {circumflex over (ω)}.sup.1.sup.R(L.sub.n) are obtained using one of the following procedures: aeroelastic analyses based on doublet lattice and finite elements methods and tools, ground vibration tests, or real-time frequency estimators.

10. The method according to claim 4, wherein step a) further comprises sampling a third discrete-time scalar signal L containing a measured shape of the flexible structure, being L.sub.n the n.sup.th sample of the L signal provided by a third active measurement source (C), this sampling being performed with a sample time Δt, and the n.sup.th sample of a signal being n∈.sup.+:n∈[1, ∞)7, wherein perfect cancellation parameters {circumflex over (K)}.sub.n.sup.1.sup.F and {circumflex over (K)}.sub.n.sup.1.sup.R, are obtained by estimations of first elastic mode unitary displacement functions for free-movement status φ.sup.1.sup.F(x, L.sub.n) and for restricted-movement status φ.sup.1.sup.R(x, L.sub.n), where x∈.sup.3 denotes a 3D coordinate vector of a generic point of the flexible structure, wherein the perfect cancellation parameters are computed as follows: ${\widehat{K}}_n^{1_F}=\frac{1}{1-{\phi }^{1_F}\left(x_A,L_n\right)/{\phi }^{1_F}\left(x_B,L_n\right)},$ ${\widehat{K}}_n^{1_R}=\frac{1}{1-{\phi }^{1_R}\left(x_A,L_n\right)/{\phi }^{1_R}\left(x_B,L_n\right)}.$ where x.sub.A and x.sub.B represent a location of the active measurement sources (A) and (B) respectively in the flexible structure, and being the relationships between the unitary displacement functions, φ.sup.1.sup.F(x.sub.A, L.sub.n)/φ.sup.1.sup.F(x.sub.B, L.sub.n) and φ.sup.1.sup.R(x.sub.A, L.sub.n)/φ.sup.1.sup.R(x.sub.B, L.sub.n) obtained by one of: aeroelastic analyses based on doublet lattice and finite elements methods and tools, ground vibration tests, or real-time elastic mode unitary displacement estimators.

11. A computer program comprising a computer program code, which, when executed by a computer device, causes the computer device to carry out all the method steps of claim 1.

12. A system comprising a flexible structure and a computer device, the computer device being configured to apply a method for computing a probability of a flexible structure to be in a physical status, said physical status being either free-movement or restricted-movement, according to claim 1.

13. The system according to claim 12, wherein the flexible structure is a flying boom so that the free-movement physical status corresponds to a free-air status of the flying boom, and the restricted-movement physical status corresponds to a coupled status of the flying boom with a receiver aircraft.

14. An aircraft comprising a system according to claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0103] These and other characteristics and advantages of the invention will become clearly understood in view of the detailed description of the invention which becomes apparent from a preferred embodiment of the invention, given just as an example and not being limited thereto, with reference to the drawings.

[0104] FIG. 1 shows a diagram with the steps of a method for detecting the physical status of a flexible structure according to an embodiment of the present invention.

[0105] FIG. 2 shows a particular embodiment of a flying boom of a tanker aircraft on which the method for detecting the physical status of this flying boom of the present invention is applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0106] The present invention firstly discloses a method for detecting the physical status, which can be a free-movement or restricted-movement status, of a flexible structure.

[0107] FIG. 1 shows a diagram with the steps of a particular embodiment of the present method to detect the physical status (free-movement, restricted movement) of a flexible structure. This flexible structure has time-varying elastic characteristics with a total number N∈.sup.+ of elastic modes, wherein i is a generic elastic mode, i∈.sup.+:i∈[1, N].

[0108] As it can be observed, the n.sup.th sample y.sub.n.sup.A and y.sub.n.sup.B of two discrete-time scalar signals y.sup.A and y.sup.B, from first (A) and second (B) sensors, are supplied to obtain in step b) the in order to obtain first elastic mode (i=1) estimated activity signal {circumflex over (γ)}.sub.n.sup.1.sup.F in free-movement status and first elastic mode (i=1) estimated activity signal {circumflex over (γ)}.sub.n.sup.1.sup.R in restricted-movement status. The signals y.sup.A and y.sup.B contain the measured dynamics of the flexible structure.

[0109] Moreover, the n.sup.th sample L.sub.n of another discrete-time scalar signal L, from a third sensor (C), is further supplied to obtain in step b) the signals {circumflex over (γ)}.sub.n.sup.1.sup.F and {circumflex over (γ)}.sub.n.sup.1.sup.R. The signal L contains the measured shape of the flexible structure.

[0110] Both signals y.sup.A and y.sup.B and signal L are sampled in step a) (not shown in FIG. 1) with a sample time Δt, and wherein the n.sup.th sample of each signal is n∈.sup.+: n∈[1,∞).

[0111] Furthermore, the notch-frequencies of free-movement and restricted-movement, {circumflex over (ω)}.sub.n.sup.1.sup.F and {circumflex over (ω)}.sup.1.sup.R respectively, at the n.sup.th sample are also supplied in step b) for obtaining the signals {circumflex over (γ)}.sub.n.sup.1.sup.F and {circumflex over (γ)}.sub.n.sup.1.sup.R. These frequencies are obtained by computing:

{circumflex over (ω)}.sub.n.sup.1.sup.F={circumflex over (ω)}.sup.1.sup.F(L.sub.n),

{circumflex over (ω)}.sub.n.sup.1.sup.R={circumflex over (ω)}.sup.1.sup.R(L.sub.n).

[0112] In a particular example, step b) further comprises computing:

{circumflex over (γ)}.sub.n.sup.i.sup.F=BP(z.sup.−1;{circumflex over (ω)}.sub.n.sup.1.sup.F)(1−{circumflex over (K)}.sub.n.sup.1.sup.F)(y.sub.n.sup.A−y.sub.n.sup.B),

{circumflex over (γ)}.sub.n.sup.i.sup.R=BP(z.sup.−1;{circumflex over (ω)}.sub.n.sup.1.sup.R)(1−{circumflex over (K)}.sub.n.sup.1.sup.R)(y.sub.n.sup.A−y.sub.n.sup.B),

[0113] BP is the discrete transfer function of a band-pass filter whit a parametric band-pass frequency.

[0114] {circumflex over (K)}.sub.n.sup.1.sup.F and {circumflex over (K)}.sub.n.sup.1.sup.R denote estimated perfect cancellation parameters of the first elastic mode (i=1) in free-movement and restricted-movement status respectively. The perfect cancellation parameters are obtained by estimations of the first elastic mode unitary displacement functions for free-movement status φ.sup.1.sup.F (x, L.sub.n) and for restricted-movement status φ.sup.1.sup.R(x, L.sub.n). x∈.sup.3 is the 3D coordinate vector of a generic point of the flexible structure.

[0115] These perfect cancellation parameters are computed as follows:

[00002]${\widehat{K}}_n^{1_F}=\frac{1}{1-{\phi }^{1_F}\left(x_A,L_n\right)/{\phi }^{1_F}\left(x_B,L_n\right)},$${\widehat{K}}_n^{1_R}=\frac{1}{1-{\phi }^{1_R}\left(x_A,L_n\right)/{\phi }^{1_R}\left(x_B,L_n\right)}.$

[0116] The location of the first A and second B sensor in the flexible structure are represented by the expression shown above x.sub.A and x.sub.R.

[0117] Once the first elastic mode (i=1) estimated activity signals {circumflex over (γ)}.sub.n.sup.1.sup.F and {circumflex over (γ)}.sub.n.sup.1.sup.R are obtained in step b), the estimated isolated free-movement and restricted-movement first elastic mode excitation signals are obtained be means of a first and second notch filters. These first elastic mode excitation signals are {circumflex over (ε)}.sub.n.sup.1.sup.F and {circumflex over (ε)}.sub.n.sup.1.sup.R and can be computed by the following expressions:

{circumflex over (ε)}.sub.n.sup.1.sup.F=NF.sub.F{circumflex over (γ)}.sub.n.sup.1.sup.F,

{circumflex over (ε)}.sub.n.sup.1.sup.R=NF.sub.R{circumflex over (γ)}.sub.n.sup.1.sup.R,

[0118] The NF.sub.F and NF.sub.R denotes the discrete transfer functions of the first and second notch filters. These notch filters are parametric notch-filters that are applied to signals γ.sub.n.sup.1.sup.F and {circumflex over (γ)}.sub.n.sup.1.sup.R with respective notch-frequencies {circumflex over (ω)}.sub.n.sup.1.sup.R and {circumflex over (ω)}.sub.n.sup.1.sup.F. The parametric transfer functions of the notch-filters in the z.sup.−1 plane are:

NF.sub.F=NF(z.sup.−1;{circumflex over (ω)}.sub.n.sup.1.sup.R),

NF.sub.R=NF(z.sup.−1;{circumflex over (ω)}.sub.n.sup.1.sup.F),

[0119] The discrete transfer function of the parametric first and second notch-filters in the z.sup.−1 plane is expressed by NF.

[0120] The method continues with step d) where the amplitude ∥{circumflex over (ε)}.sub.n.sup.1.sup.F∥ and ∥{circumflex over (ε)}.sub.n.sup.1.sup.R∥ of the isolated elastic mode excitation signals {circumflex over (ε)}.sub.n.sup.1.sup.F and {circumflex over (ε)}.sub.n.sup.1.sup.R are estimated by amplitude demodulation.

[0121] Once the amplitude ∥{circumflex over (ε)}.sub.n.sup.1.sup.F∥ and ∥{circumflex over (ε)}.sub.n.sup.1.sup.R∥ are estimated, the estimated probability p.sub.n.sup.R of the flexible structure to be in a restricted-movement status is recursively computed according to step e). This estimated probability is defined as:

P.sub.n.sup.R=max(0,min(1,P.sub.n-1.sup.R+(λ.Math.U.sub.n))).

[0122] For the above estimated probability, λ is an update gain constant with λ>0, and P.sub.n-1.sup.R is a previous value of the estimated probability of the flexible structure in a restricted-movement status at the (n−1).sup.th sample. Therefore, when n=1; then P.sub.n-1.sup.R=0 (being this the first time that the step e) of the method is applied).

[0123] Furthermore, U.sub.n is defined as the following expression:

U.sub.n=(∥{circumflex over (ε)}.sub.n.sup.1.sup.F∥−∥{circumflex over (ε)}.sub.n.sup.1.sup.R∥).sup.2P.sub.n-1.sup.R−∥{circumflex over (ε)}.sup.1.sup.R∥(∥{circumflex over (ε)}.sub.n.sup.1.sup.F∥−∥{circumflex over (ε)}.sub.n.sup.1.sup.R),

[0124] For detecting if the flexible structure is in a free-movement status or restricted-movement status in step f), a discrete state Boolean signal R.sub.n is recursively computed at the n.sup.th sample as follows:

[0125] if P.sub.n.sup.R≥p.sub.R and R.sub.n-1=false, then R.sub.n=true being the flexible structure in the restricted-movement status, otherwise R.sub.n=false or

[0126] if P.sub.n.sup.R≤p.sub.F and R.sub.n-1=true, then R.sub.n=false being the flexible structure in the free-movement status, otherwise R.sub.n=true.

[0127] R.sub.n-1 is a previous value of the discrete state Boolean signal at the (n−1).sub.th sample, and when n=1, it is the first time that the step f) of the method is applied, and therefore, R.sub.n-1=false. This implies that the flexible structure is in a free-movement status.

[0128] p.sub.R is a predetermined restricted-movement probability parameter and must be greater than 0 and lower than 1; and p.sub.F is a predetermined free-movement probability parameter and must be greater or equal to 0 and lower or equal to 1. In a particular example, p.sub.Rϵ[0.75, 0.95] and p.sub.Fϵ[0.05, 0.25].

[0129] Therefore, when R.sub.n=false, then the flexible structure is in a free-movement status; and when R.sub.n=true, then the flexible structure is in a restricted movement.

[0130] The flexible structure is controlled by flight control laws (CLAWs) that comprise specific filtering modes for free-movement or restricted-movement status. Particularly, the filtering mode of the CLAWs is set by means of a binary discrete input signal M. The n.sup.th sample M.sub.n of the M signal is defined as:

[0131] M.sub.n=0 sets the filtering mode to free-movement filtering mode, or

[0132] M.sub.n=1 sets the filtering mode to restricted-movement filtering mode.

[0133] Furthermore, the present method comprises the step g) where the filtering mode is set as follows:

[0134] R.sub.n=true, the filtering mode is switched to the restricted-movement filtering mode by setting the n.sup.th sample of the input signal M.sub.n to one (M.sub.n=1),

[0135] If R.sub.n=false, the filtering mode is switched to the free-movement filtering mode by setting the n.sup.th sample of the input signal M.sub.n to zero (M.sub.n=0).

[0136] FIG. 2 shows a particular example of a flying boom (1) of a tanker aircraft, particularly a zoom of the tail cone area of a tanker aircraft with the flying boom (1) deployed. This flying boom (1) comprises two active measurement sources, which correspond to a first sensor (A) and a second sensor (B). In particular, the first sensor (A) is a ball joint angle sensor located on the gimballed attachment (2) of the flying boom (1) to the tanker aircraft; and the second sensor (B) is an Inertial Measurement Unit (IMU) that is located in the bulb (3) of the flying boom (1) close to the hinge of the control surfaces (4).

[0137] The first sensor (A) provides a first discrete-time scalar signal y.sup.A and the second sensor (B) provides a second discrete-time scalar signal y.sup.B. Both signals contain the dynamics of the flying boom (1) measured at different locations; the dynamics defined wither by angular orientation, angular rates or angular accelerations of the flying boom (1).

[0138] The elastic modes shapes and undamped elastic modes frequencies of the flying boom (1) flexible structure suffer large variations derived from fast changes in the exogenous boundary conditions acting on the nozzle. In this particular case of a flying boom (1), these changes in the exogenous boundary conditions occur during transitions from free-movement status to restricted-movement status of the flying boom (1) flexible structure and vice versa.

[0139] For detecting the physical status of the flying boom (1) according to the present method, signals y.sup.A and y.sup.A are sampled with a sample time Δt so that y.sub.n.sup.A and y.sub.n.sup.B are the n.sup.th sample of the respective signal provided by the first (A) and second (B) sensor and n∈.sup.+:n∈[1, ∞).

[0140] This flying boom (1) further comprises a third active measurement source corresponding to a third sensor (C). In particular, this third sensor (C) is a potentiometer located in the telescopic beam (5) which measures the length (L) of the beam section that is cantilevered and exposed to the air free stream.

[0141] This third sensor (C) provides a third discrete-time scalar signal L which provides information related to the current shape and morphology of the flying boom (1), particularly, the length (L) of the telescopic beam (5) section that is cantilevered and exposed to the air free stream that changes its configuration over time with extension or retraction movements.

[0142] From the signals measured by at least the first (A), the second (B) and the third (C) sensors arranged along the flying boom (1) structure, the present method is able to detect the physical status of the flying boom (1), and thus, it is able to detect if there is any mismatch between the actual physical status of the flying boom (1) and the filtering mode of the flight control laws (CLAWs).

[0143] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.