Patent ID: 12233996

DESCRIPTION OF REFERENCE NUMERALS

Fuselage1; detection apparatus2; propeller assembly7; sensing apparatus8; control apparatus9;main body compartment10; detection head cover101; coupling portion102; control compartment shell103; special-shaped compartment104; control compartment cover105; battery compartment cover106; battery compartment shell107; compartment cover transition section108; grip109;alloy skeleton20; head skeleton201; middle skeleton202; tail skeleton203;streamlined shell206;motion assisting module3; fixing support301; motor302; spoiler303;adaptive magnetization module4; lifting plate401; first small hydraulic rod402; second small hydraulic rod403; magnetization fixing module404; bearing plate405; second large hydraulic rod406; first large hydraulic rod407; adaptive adjustment holding mechanism408; bottom connecting skeleton409; mounting bottom plate410;underwater vision matrix module5; linear actuator501; clamping plate502; matrix collar503; waterproof motor504; waterproof camera505; motion frame506; hinged motion frame507;variable stiffness flexible hoop self-stabilizing module6; main fixing frame601; hydraulic mechanical claw60; variable stiffness cladding array607; gap-filling cladding unit608; and carbon fiber interlayer609.

DETAILED DESCRIPTION OF EMBODIMENTS

The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Apparently, the described embodiments are merely a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments derived by a person of ordinary skill in the art from the embodiments of the present invention without any creative effort fall within the scope of protection of the present invention.

In the description of the specification and claims, it should be understood that the terms “upper”, “lower”, “left”, “right”, “front”, “rear”, “top”, “bottom”, “inner”, “outer”, and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are merely for convenience in describing the embodiments of the present invention, rather than to indicate or imply that the referred apparatus or components must have a particular orientation or be constructed and operated in a particular orientation, and thus they should not be construed as limiting the embodiments of the present invention.

Furthermore, the terms “first”, “second”, etc. in the specification and claims are merely provided for descriptive purposes of distinguishing between the same technical features, and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated, nor necessarily describing the order or chronology. The terms are interchangeable where appropriate. Thus, a feature defined as “first” or “second” may explicitly or implicitly include one or more of these features.

Referring toFIG.1toFIG.24, an embodiment of the present invention provides an underwater submersible robot. The underwater submersible robot includes: a fuselage1, a detection apparatus2, a propeller assembly7, a sensing apparatus8, and a control apparatus9. The detection apparatus2is disposed on the fuselage1and configured to detect an underwater target. The propeller assembly7is disposed on the fuselage1and configured to drive the underwater submersible robot underwater. The sensing apparatus8is disposed on the fuselage1and configured to sense an attitude and depth of the fuselage1. The control apparatus9is disposed on the fuselage1, connected to the detection apparatus, the sensing apparatus and the propeller assembly7, and configured to execute an active disturbance rejection intelligent control strategy. The active disturbance rejection intelligent control strategy includes the following contents:calculating a first difference between a current actual attitude of the fuselage1and a desired attitude and a second difference between an actual depth and a desired depth;inputting the first difference and the second difference into a set terminal sliding mode surface to obtain an output value of the terminal sliding mode surface;using the output value as an input of a preset high-order observer, a radial basis function neural network and a terminal sliding mode control law, respectively, and using an output of the high-order observer and an output of the radial basis function neural network as a compensation input of the terminal sliding mode control law to obtain a virtual force outputted by the terminal sliding mode control law;performing power distribution for each propeller of the propeller assembly on the basis of the virtual force to obtain a propelling force of each propeller; andcontrolling a propelling operation of the propellers on the basis of the propelling force.

As an example, the sensing apparatus8includes a depth sensor, an attitude detection sensor, etc., and the sensing apparatus8may detect relevant actual attitude data and actual depth data and then transmit same to the control apparatus9.

Specifically, an attitude deviation and a depth deviation are inputted into the set terminal sliding mode surface, and then the terminal sliding mode surface is used as the input of the preset high-order observer, the radial basis function neural network, and the terminal sliding mode control law, respectively. Since the output of the terminal sliding mode control law is prone to buffeting, the high-order observer is used for more accurately observing the buffeting state and estimating the deviations, which may suppress the buffeting of the output of the terminal sliding mode control law. The radial basis function neural network is an efficient feed-forward neural network capable of achieving nonlinear function approximation and real-time system optimization, and thus the introduction of the radial basis function neural network may improve the stability and anti-disturbance capacity of a sliding mode control system. Therefore, by using the output of the high-order observer and the output of the radial basis function neural network as the compensation input of the terminal sliding mode control law, the virtual force outputted by the terminal sliding mode control law may ultimately be more reasonable, thus ultimately improving the anti-turbulence capacity of the underwater submersible robot.

According to the embodiment of the present invention, the first difference between the current actual attitude of the fuselage and the desired attitude and the second difference between the actual depth and the desired depth are calculated; the first difference and the second difference are inputted into the set terminal sliding mode surface to obtain the output value of the terminal sliding mode surface; the output value is used as the input of the preset high-order observer, the radial basis function neural network, and the terminal sliding mode control law, respectively, and the output of the high-order observer and the output of the radial basis function neural network are used as the compensation input of the terminal sliding mode control law, so that the data deviation may be compensated for the current underwater turbulence, and the terminal sliding mode control law may ultimately output a more accurate virtual force; power distribution is carried out for each propeller of the propeller assembly on the basis of the virtual force to obtain the propelling force of each propeller; the propellers of the underwater submersible robot are controlled to operate on the basis of the propelling force. Thus, more reasonable motion control may be carried out for the current underwater disturbance. It can be seen that the embodiment of the present invention may improve the anti-disturbance capacity of the underwater submersible robot against underwater turbulence, so as to achieve the autonomous fuselage stabilization under the complex environment and the autonomous extrication operation under the emergency environment, which effectively achieves the autonomous strong anti-disturbance function, improves the operation safety and stability of the equipment, and reduces the occurrence probability of accidents of the equipment. Moreover, based on the control strategy, the intelligent operation of the underwater unmanned aerial vehicle is achieved, the efficiency of underwater engineering detection is substantially improved, the safety of underwater engineering detection work is effectively improved, the need for divers to directly participate in the operation is eliminated, and the risk faced by the staff when operating in the underwater environment is greatly reduced.

As an improvement on the above solution, the control apparatus9, when configured to perform power distribution for each propeller of the propeller assembly on the basis of the virtual force to obtain a propelling force of each propeller, is specifically configured to:filter the virtual force using a second-order filter, and convert the filtered virtual force into the propelling force of each propeller of the propeller assembly by power distribution.

Specifically, referring toFIG.23, the specific implementation process of the active disturbance rejection intelligent control strategy is as follows:

Dynamics Modeling:

Firstly, two fundamental coordinate systems of the underwater submersible robot, namely a fixed coordinate system E−ξηζ (fixed system) and a moving coordinate system G−xyz (moving system), are established.

The Jacobi matrix has a form of J(η)∈R6×6and is expressed in the form:

J⁡(η)=[T103×303×3T2](1)

A linear velocity coordinate transformation matrix T1between the moving system and the fixed system is:

T1=[cos⁢θ⁢cos⁢ψsin⁢φ⁢sin⁢θ⁢cos⁢ψ-cos⁢φ⁢sin⁢ψcos⁢φ⁢sin⁢θ⁢cos⁢ψ+sin⁢φ⁢sin⁢ψcos⁢θ⁢sin⁢ψsin⁢φ⁢sin⁢θ⁢sin⁢ψ+cos⁢φ⁢cos⁢ψcos⁢φ⁢sin⁢θ⁢cos⁢ψ-sin⁢φ⁢sin⁢ψ-sin⁢θsin⁢φ⁢cos⁢θcos⁢φ⁢cos⁢θ](2)

A transformation matrix T2of an angular velocity from the moving system to the fixed system is:

T2=[1sin⁢φ⁢tan⁢θcos⁢φ⁢tan⁢θ0cos⁢φ-sin⁢φ0sin⁢φ⁢sec⁢θcos⁢φ⁢sec⁢θ](3)

On the basis of existing modeling experience, the following assumptions are made:(1) The underwater submersible robot may be regarded as a rigid body with constant mass, ignoring the change of density, pressure and other conditions in water.(2) When the underwater submersible robot operates, hardware in the fuselage remains fixed, that is, the center of gravity and buoyant center of the underwater submersible robot remain unchanged.(3) The drag force and moment disturbance brought by a buoyant umbilical cable are neglected.(4) The underwater submersible robot is in water throughout the operation, and is in a wet state.(5) The pitch angle θ is limited as |θ|θmax≤π/2 to prevent the singularity of J(η). θmax>0 is a known constant. J(η) is invertible and bounded. There exists a known constantJ>0 that enables supn∥J(η)∥<J.

Based on the above assumptions, a six-degree-of-freedom nonlinear dynamics equation of the underwater submersible robot is established as follows:
M{dot over (v)}+C(v)v+D(v)v+g(η)=τ+τdη(4)

where M∈R6×6denotes an inertia matrix; C(v)∈R6×6denotes a Coriolis matrix and a centripetal matrix; D(v)∈R6×6denotes a damping matrix; g(η)∈R6denotes a restoring force and moment matrix; τ∈R6denotes a propelling force and moment; and Td1∈R6denotes model uncertainty disturbance.

Double-Loop Control Strategy:

Let e1=x1−x1d, e2=x2−x2ddenote a tracking error and a first-order derivative of a second-order system, respectively.

Then, a velocity tracking error sliding mode surface is defined as:
Sν=ν−νr(5)

In combination with (4), νc∈R6is designed as a velocity control command for a reference velocity:

vc=J-1(x1)⁢x2d-J-1(x1)⁢(K1⁢e1+K2⁢∫0te1⁢d⁢t)(6)

where K1=diag[k11, k12. . . , k1n]∈R6×6and

K2=diag[k21, k22, . . . , k2n]∈R6×6are both pre-designed constant positive definite matrices, and k1i, k2i(i=1, . . . , 6) satisfies k1i2−4k2i≥0. In combination with (5) and (6), an outer-loop PID sliding mode surface is designed as:

Sν˜=e2+K1⁢e1+K2⁢∫0te1⁢dt(7)

On the basis of (7), an inner-loop terminal sliding mode surface is designed as:

ST=Sν˜+β1⁢sigγ1⁢Sν˜+β2⁢sigγ2⁢d⁢Sν˜d⁢t(8)

The differential of ν is:

dvd⁢t=M-1(τ+τd⁢η-C⁡(v)⁢v-D⁡(v)⁢v-g⁡(x1))(9)(7) is differentiated and substituted into (5) to obtain

dS⁢v~dt=dvdt-dvcd⁢t=M-1(τ+τd⁢η-C⁡(v)⁢v-D⁡(v)⁢v-g⁡(x1))-v˙c(10)(10) is substituted into (8) to obtain:

ST=Sv~+β1⁢s⁢i⁢gγ1⁢Sν˜+β2⁢s⁢i⁢gγ2[M-1(τd⁢η-C⁡(v)⁢v-D⁡(v)⁢v-g⁡(x1))-v.c+M-1⁢τ](11)

A derivative of STis taken as:

S˙T=S˙v~+β1⁢γ1⁢❘"\[LeftBracketingBar]"Sν˜❘"\[RightBracketingBar]"γ1-1⁢S˙v~+β2⁢γ2⁢❘"\[LeftBracketingBar]"S.v~|γ2-1[⁠M-1(τ.d⁢η-C.(v)⁢v-C⁡(v)⁢v˙-D˙(v)⁢v-D⁡(v)⁢v.-g˙(x1))-v¨c+M-1⁢τ˙](12)=-{-S˙v~-β1⁢γ1⁢❘"\[LeftBracketingBar]"β1❘"\[RightBracketingBar]"γ1-1⁢S˙v~+β2⁢γ2⁢❘"\[LeftBracketingBar]"S˙v~❘"\[RightBracketingBar]"γ2-1[M-1(C˙(v)⁢v+C⁡(v)⁢v.+D⁡(v)⁢v+D⁡(v)⁢v.+g.(x1))+v¨c]}+Kd⁢M-1⁢τ˙+Kd⁢M-1⁢τ˙d⁢ηf=-S´v~-β1⁢γ1⁢❘"\[LeftBracketingBar]"β1❘"\[RightBracketingBar]"γ1-1⁢S˙v˜+β2⁢γ2⁢❘"\[LeftBracketingBar]"S.v~❘"\[RightBracketingBar]"γ2-1[M-1(C.(v)⁢v.+C⁡(v)⁢v.+D.(v)⁢v+D⁡(v)⁢v.+g˙(x1))+v¨c]-Kd⁢M-1⁢τ˙d⁢ηserves as a lumped unknown function, and G=KdM−1. The above equation may then be simplified to:
{dot over (S)}T=−ƒ+G{dot over (τ)}(13)

The Gaussian radial basis function (RBF) neural network has the function approximation ability and may be applied to control over complex nonlinear systems with uncertainty. The present invention designs six identical Gaussian radial basis function (RBF) neural networks. The ideal value of the unknown function ƒ to be approximated may be described as:
ƒ=W*Tϕ(ST)−ε  (14)where ϕ(ST)∈R30, s=[ST1, ST2, . . . , STn] denotes a neural network input vector, W*=[W*1, W*2, . . . , W*n]Tdenotes an ideal weight vector, W*i=[W*i1, W*i2, . . . , W*i5]T(i=1 . . . 6, 5 denotes the number of hidden nodes),ϕ(s)=diag[ϕ1(ST1), ϕ2(ST2), . . . , ϕ6(ST6)] has a basis function of ϕi(STi)=[ϕi1(STi), ϕi2(STi), . . . , ϕi5(STi)]T, and ε=[ε1, ε2, . . . , ε6]Tis a bounded approximation vector. Therefore, ε≤εandε>0 may be obtained. The Gaussian radial basis function (RBF) considered in the present invention is given.

ϕik(si)=exp[(si-cik)T⁢(si-cik)bik2]
i=1,2, . . . ,6,k=1,2, . . . ,5  (15)

Cikand bikdenote the center and width of the Gaussian function, respectively.

The vector for estimating the weight is expressed as
Ŵ=W*+{tilde over (W)}(16)
where W denotes an error vector for estimating the weight.

The unknown function ƒ∈R6is set as an output of the RBF, so it may be expressed as
{circumflex over (ƒ)}=ŴTϕ(ST)  (17)

The proposed design of a double-loop neural network sliding mode controller is as follows:

τ˙=1G⁢(fˆ-K⁢ST)(18)
where K=diag[K1, K2, . . . , Kn] is a constant diagonal matrix, and (18) is substituted into (13) to obtain
{dot over (S)}T={tilde over (ƒ)}−KST(19)
where {tilde over (ƒ)}={circumflex over (ƒ)}−ƒ.

A Lyapunov function is selected:
V=V1+V2+V3(20)
where

V1=12⁢∑i=1n⁢(W~iT⁢Ii-1⁢W~i)(21)V2=12⁢STT⁢ST(22)V3=12⁢∑i=1n⁢Θ~iT⁢Θ~i(23)

Proof: (20) is differentiated

V˙1=∑i=1n⁢W~iT⁢Ii-1⁢W~.i(24)

Since W* is a constant and=, the following may be obtained on the basis of (24):

V˙1=∑i=1n⁢W~iT⁢Ii-1⁢Wˆi(25)

Now, an update law may be substituted as:
i=Ii(siϕi(si)+αiŴi),i=1,2, . . . ,n(26)
where αiis a small constant used for denoting a correction term, which helps to improve the robustness of a controlled system.

By substituting the update law (26) into (25), the following may be obtained:

V˙1=-∑i=1n⁢si⁢W~iT⁢ϕi(si)-∑i=1n⁢αi⁢W~iT⁢W^i(27)
where
−{tilde over (W)}iTŴi=−{tilde over (W)}iTW*i−{tilde over (W)}iT{tilde over (W)}i(28)

In combination with lemma 2, the following may be obtained on the basis of (28):

-12⁢(W~iT⁢W~i+Wi*T⁢Wi*)≤-W~iT⁢Wi*≤12⁢(W~iT⁢W~i+Wi*T⁢Wi*)(29)⁢9)

In combination with (28) and (29), the following may be obtained:

-W~iT⁢W^i≤12⁢W~iT⁢W~i+12⁢Wi*T⁢Wi*-W~iT⁢W~i≤-12⁢W~iT⁢W~i+12⁢Wi*T⁢Wi*(30)

On the basis of (30), the following may be obtained:

V˙1≤-∑i=1n⁢si⁢W~iT⁢ϕi(si)-∑i=1n⁢α12⁢W~iT⁢W~i+∑i=1n⁢α12⁢Wi*T⁢Wi*(31)

(22) is differentiated:

V˙2=STT⁢S˙T=STT(f~-KST)(32)

(13) and (17) are substituted into (32) to obtain:

V˙2=STi⁢(W^iT⁢ϕi⁢(ST)-Wi*T⁢ϕi⁢(ST))+STT⁢(ε-K⁢ST)=∑i=16⁢STi⁢W~T⁢ϕi(ST)+sT⁢ε-STT⁢K⁢ST(33)
where {tilde over (W)}T=ŴiT−W*iT.

On the basis of (33), the terminal sliding mode surface error may be obtained as follows:

STT⁢ε≤12⁢STT⁢ST+12⁢εT⁢ε(34)

Because of (33), (34) may become an inequality as:

V˙2≤∑i=16⁢STi⁢W~T⁢ϕi(ST)+12⁢STT⁢ST+12⁢εT⁢ε-STT⁢KST(35)

The differential term of the terminal sliding mode surface corresponds to the dynamics equation (4) of the underwater submersible robot, (4) is subdivided into a standard term and an uncertainty term, and because the underwater submersible robot has high nonlinearity, high coupling and strong disturbance, the dynamics equation of the standard term is inaccurate, but the terminal sliding mode surface needs high model accuracy. Thus, it is necessary to design a high-order observer to compensate for the uncertainty term. Because of (8), the following may be obtained:
{dot over (ν)}=τ̌+τ̌dη−Č(ν)c−Ď(ν)ν−{hacek over (g)}(x1)  (36)
where
τ̌=M−1τ,Č(ν)=M−1C(ν),Ď(ν)=M−1D(ν),ǧ(x1)=M−1g(η),τ̌dη=M−1τdη

Because τ̌idηof Siin (36) is an unknown term, high-order observers πiare designed. The adopted high-order observers are as follows:
{dot over (π)}i0=πi1−Či(νi)νi−Ďi(νi)νi−ǧi(ηi)+ϑi0(νi−πi0)
{dot over (π)}i1=πi2+ϑi1(νi−πi109)
{dot over (π)}i2=πi3+ϑi2(νi−πi∩)
.
.
.
{dot over (π)}im=ϑim(νi−πi0)  (37)

where πi0, πi1, πi2, . . . , πimare estimated values of νi, τ̌idη, τ̌idη, . . . , τ(m)idη, respectively, and ϑi0, . . . , ϑim>0. Θi0(τ)=νi−πi0, Θi1(τ)=τ̌idη−πi1, . . . , Θim(τ)=τ̌idη(m)−πimis given, and in combination with (37), the following may be obtained:
i0={tilde over (Θ)}i1−ϑi0{tilde over (Θ)}i0
i0={tilde over (Θ)}i2−ϑi1{tilde over (Θ)}i0
i2={tilde over (Θ)}i3−ϑi2{tilde over (Θ)}i0
im=τ̌idη(m)−ϑim{tilde over (Θ)}i0(38)

In combination with (37) and (38), the following may be deduced:
i=φi{tilde over (Θ)}i+Γiτ̌idη(m)(39)
where

φi=[-ϑi⁢010…0-ϑi⁢111…0⋮⋮⋮⋱⋮-ϑi⁢m-100…1-ϑi⁢m00…0],Γi=[0⋮⋮⋮1](40)

Then, the positive definite function (23) is selected to obtain:

V3⁢i=12⁢Θ~iT⁢Θ~i(41)

V3iis differentiated, and (39) is called to obtain:
3i={tilde over (Θ)}iTi={tilde over (Θ)}iT(φi{tilde over (Θ)}i+Γiτ̌idη(m)(42)

The result of lemma 2 is applied to (42) to obtain:

V˙3⁢i≤Θ~iT(φi+ξi⁢I)⁢Θ~i+1Υi⁢ξi2(43)
where Yi>0, i=1, 2, . . . , 6, and I is the quadratic of τ̌idη(m).

Now V3is differentiated to obtain:

V˙3=∑i=16⁢Θ~iT⁢Θ~.i(44)

(43) is substituted into 44) to obtain:

V˙3≤∑i=16⁢Θ~iT(φi+Υi⁢I)⁢Θ~i+1Υi⁢ξi2(45)

(20) is differentiated, and (31), (35) and (45) are called to obtain:

V˙=V˙1+V˙2+V˙3≤-∑i=16⁢STi⁢W~iT⁢ϕi(STi)-∑i=16⁢αi2⁢W~iT⁢W~i+∑i=16⁢αi2⁢Wi*T⁢Wi*+∑i=16⁢si⁢W~T⁢ϕi(ST)+12⁢STT⁢ST+12⁢εT⁢ε-STT⁢K⁢ST+∑i=16⁢Θ~iτ(φi+Υi⁢I)⁢Θ~i+1Υi⁢ξi2≤-STT(K-12⁢I)⁢ST-∑i=16⁢αi2⁢W~iT⁢W~i-∑i=16⁢Θ~iT(-φi-Υi⁢I)⁢Θ~i+∑i=16+1Υi⁢ξi2+∑i=16⁢αi2⁢Wi*T⁢Wi*+12⁢εT⁢ε(46)

Then, lemma 1 is cited to obtain:
{dot over (V)}≤−ρ({dot over (V)}1+{dot over (V)}2+{dot over (V)}3)+μ  (47)
where

ρ=min⁡(mini=1,2,…,6(αi),2⁢λmin(K-12⁢I),-2⁢λmin(φi+Υi⁢I))(48)

μ=∑i=16+1δi⁢ξi2+∑i=16⁢αi2⁢Wi*T⁢Wi*+12⁢εT⁢ε(49)

λmin(·) denotes the minimum eigenvalue of the matrix. By making

λmin(K-12⁢I)>0
and λmin((φi+YiI)<0, ρ>0 is ensured, apparently, μ being a normal number.

Proof is completed.

Theorem 1: For the described underwater submersible robot system, under the control law (18) and the update law (26), the sliding mode surface error and a derivative thereof are semi-globally uniformly bounded as long as initial conditions are bounded.

Proof: (47) is multiplied by eβtto obtain:

dd⁢t⁢(V⁢eρ⁢t)≤μ⁢eρ⁢t(50)

(50) is differentiated to obtain:

V≤μρ+e-ρ⁢t(V⁡(0)-μρ)≤μρ+V⁡(0)⁢e-ρ⁢t(51)

(21), (22) and (23) are substituted into (51) respectively to obtain:

V1=12⁢∑i=16⁢(W~iT⁢Ii-1⁢W~i)≤V≤μρ+V⁡(0)⁢e-ρ⁢t(52)V2=12⁢STT⁢ST≤V≤μρ+V⁡(0)⁢e-ρ⁢t(53)V3=12⁢∑i=16⁢Θ~iT⁢Θ~i≤V≤μρ+V⁡(0)⁢e-ρ⁢t(54)Ω⁢W~i:={W~i∈R6❘"\[RightBracketingBar]"⁢W~i≤2⁢(μp+V⁡(0)⁢e-ρ⁢t)mini=1,2,…,6(Ii-1)},i=1,…,6⁢∀t∈[0,+∞)(55)Ω⁢ST:={ST∈R6❘"\[RightBracketingBar]"⁢ST≤2⁢μρ+V⁡(0)⁢e-ρ⁢t}⁢∀t∈[0,+∞)(56)Ω⁢Θ~i:={Θ~i∈R6❘"\[RightBracketingBar]"⁢Θ~i≤2⁢μρ+V⁡(0)⁢e-ρ⁢t)},i=1,…,6⁢∀t∈[0,+∞)(57)

Proof is completed.

On the basis of lemma 1, the inner-loop terminal sliding mode surface may be ST=0 within the finite time treach, so the following may be obtained:

Sν~+β1⁢s⁢i⁢gγ1⁢Sv~+β2⁢sigγ2⁢dSv~dt=0Sv~+β1⁢sigγ1⁢Sv~+β2⁢s⁢i⁢gγ2⁢d⁢Sv~dt=0,i=1,…,6(58)

The following two forms may be obtained using (58):

Sv~+β1⁢s⁢i⁢gγ1⁢Sv~+(β2-ST·sig-γ2-dSv~dt)⁢s⁢i⁢gγ2⁢dSv~d⁢t=0(59)e1+β2⁢sigγ2⁢e2+(β1-ST·sig-γ1⁢Sv~)⁢sigγ1⁢Sv~=0(60)

When

β2-ST·(sig-γ2⁢d⁢Sv~dt)>0
holds, (60) still remains in s=e1+β1sigY1e1+β2sigY2e2. Therefore, the system trajectory may continue to converge to the sliding mode surface s until reaching

sigγ2⁢d⁢Sv~dt<1β2⁢ST=1β2⁢Ξ,
so a control error

dSv~d⁢t
may converge to the following region within the finite time:

❘"\[LeftBracketingBar]"dSv~d⁢t❘"\[RightBracketingBar]"≤❘"\[LeftBracketingBar]"1β2⁢ST❘"\[RightBracketingBar]"1γ2<❘"\[LeftBracketingBar]"1β2⁢ϕ❘"\[RightBracketingBar]"1γ2(61)

(59) may be proved using the same proof steps, thus obtaining

s⁢i⁢gγ1⁢Sv~<1β1⁢ST=1β1⁢Ξ,
where Ξ denotes the Greek character “xi”, and Ξ is as a constant, representing the upper bound in the equation. Then, by combining (61) and

sigγ2⁢dSv~d⁢t<1β2⁢ST=1β2⁢Ξ,
the following may be obtained:

Sv~≤❘"\[LeftBracketingBar]"ST❘"\[RightBracketingBar]"+❘"\[LeftBracketingBar]"β1⁢s⁢i⁢gγ1⁢ST❘"\[RightBracketingBar]"+❘"\[LeftBracketingBar]"β2⁢s⁢i⁢gγ2⁢d⁢Sv~dt❘"\[RightBracketingBar]"=3⁢Ξ(62)dSv~d⁢t≤❘"\[LeftBracketingBar]"dSv~d⁢t❘"\[RightBracketingBar]"≤❘"\[LeftBracketingBar]"1β2⁢ϕ❘"\[RightBracketingBar]"1γ2(63)

Therefore, on the basis of the above analysis, the velocity tracking error converges to zero within the finite time, and the initial value of the total time spent is {tilde over (ν)}(0) to zero.
tsum=treach+i=1,2, . . . ,6max(tc)  (64)

After t>tsum, the following may be obtained from (7):
V=Vc(65)

S{tilde over (ν)}=0 may be obtained from (65), and the following may be obtained from (6):
e2+K1e1+K2∫0te1dt=0
e2i+K1ie1i+K2i∫0te1idt=0·i=1, . . . ,6  (66)

As long as (66) satisfies K1i2−4K2i≥0, i=1, . . . , 6, ∫0tηidt(i=1, . . . , 6) may converge to zero within the finite time, and thus, like the velocity tracking error of (58), the position tracking error e1may converge exponentially to zero after tsum.

It can be understood that by considering (66) as a zero-input second-order filter system, the intrinsic frequency and damping ratio thereof may be expressed as

ωn=K21
and

ζ=K12⁢K2*1,
respectively. The time-domain method is adopted for analysis, firstly, K1i2−4K2i≥0, =1, . . . , 6 has been assumed, the filter system is capable of exponentially converging, and the closer the damping ratio ζ is to 0.707, the faster the second-order filter system converges, and the smaller the amount of overshooting is, which is the best state for the comprehensive performance of the second-order filter system.

In summary, by means of the active disturbance rejection intelligent control strategy, the robot autonomously compensates for the water current turbulence during trajectory tracking, so as to achieve accurate path tracking and navigation control.

As an improvement to the above solution, referring toFIG.1andFIG.2, the propeller assembly7includes four propellers, the four propellers are disposed at two ends of two sides of the fuselage1respectively in a manner of rotating up and down and left and right, and the four propellers are connected to the control apparatus9.

As an improvement to the above solution, referring toFIG.1toFIG.4, the fuselage1includes a main body compartment10, two alloy skeletons200and two streamlined shells206. The two alloy skeletons200are disposed on the main body compartment10in a manner of rotating around an axial direction of the main body compartment10. The two streamlined shells206enclose the two alloy skeletons200in a one-to-one correspondence manner and are correspondingly connected to the two alloy skeletons200.

Specifically, the main body compartment10includes, in a lengthwise direction, a detection head cover101, a coupling portion102, a control compartment shell103, a special-shaped compartment104, a control compartment cover105, a battery compartment cover106, a battery compartment shell107, a compartment cover transition section108, and a grip109connected in sequence. The interior of the control compartment shell103is used for accommodating the control apparatus9, the interior of the detection head cover101is used for accommodating a camera, and the interior of the battery compartment cover106is used for accommodating a battery compartment. A portion of the coupling portion102in contact with the control compartment shell103and a portion of the coupling portion in contact with the detection head cover101are provided with annular grooves along an outer periphery of the coupling portion, O-shaped seal rings are mounted in the annular grooves, the portions of the coupling portion102extend into the detection head cover101and the special-shaped compartment104and fit tightly, and the portions of the coupling portion102extending into the detection head cover101and the special-shaped compartment104are provided with jackscrews. A portion of the special-shaped compartment104in contact with the control compartment shell103is provided with an annular groove with an O-shaped seal ring, and an outer periphery of the special-shaped compartment104is concave to form eight tables for mounting of watertight joints. The sensing apparatus including the depth sensor, a switch, etc. is disposed in the special-shaped compartment and leads out wires by means of the watertight joints. A middle position of the control compartment cover105is concave to form an accommodation slot for accommodating a male socket plug connected to the battery compartment cover106. A middle position of the battery compartment cover106is concave to form an accommodation slot for accommodating a female socket plug in plugged connection with the male socket plug. An O-shaped seal ring is disposed between connecting portions of the battery compartment cover106and the battery compartment shell107. A battery platform is provided inside the battery compartment cover106for placement of a battery. An O-shaped seal ring and a jackscrew are provided at a connecting position of one end of the compartment cover transition section108and the battery compartment shell107. The grip109is provided at the other end of the compartment cover transition section108.

As an improvement to the above solution, referring toFIG.3andFIG.4, the alloy skeletons200include head skeletons201, middle skeletons202, and tail skeletons203disposed in sequence along the lengthwise direction of the main body compartment10. The head skeletons201, the middle skeletons202and the tail skeletons203are connected to two ends of two sides of the main body compartment10respectively by means of the coupling portion102. The main body compartment10is connected to the corresponding streamlined shells206by means of the head skeletons201, the middle skeletons202and the tail skeletons203. An expansion skeleton is disposed at a bottom of the main body compartment10, and holes are reserved in the expansion skeleton for mounting of an expansion module.

The fuselage of the underwater submersible robot is more specifically described below for ease of understanding:

Referring toFIG.1toFIG.8, the fuselage of the underwater submersible robot includes three modules, namely, the main body compartment1, the high-strength lightweight alloy skeletons200, and the streamlined shells206, to form the main body of an unmanned aerial vehicle. The main body compartment1module includes nine portions, namely the detection head cover101, the coupling portion102, the control compartment shell103, the special-shaped compartment104, the control compartment cover105, the battery compartment cover106, the battery compartment shell107, the compartment cover transition section108, and the grip109. A lens cover plate117, an O-shaped ring122, a camera mounting plate120, an EVA foam119, a tempered glass118, and an ultra definition camera121are disposed inside the detection head cover101. The ultra definition camera121is mounted on the camera mounting plate120, and the camera mounting plate120is fixed to the detection head cover101by screws123for image recognition.

An electronic component placement plate is disposed inside the control compartment shell103. The electronic component placement plate is fixed to an inner wall of the coupling portion102by means of copper posts124. Various types of control components and electronic components may be mounted and placed on the electronic component placement plate. The electronic component placement plate is divided into a left baffle plate128, a right baffle plate125, and a middle supporting plate126. The left and right baffle plates are connected and fixed to the coupling portion102by means of the copper posts124. The middle supporting plate126is clamped by the left and right baffle plates. Two sides of the middle supporting plate126may be embedded in slots127in the left and right baffle plates to achieve fixation. The left and right baffle plates are designed to be hollow in the middle to facilitate the passage of wires, and only the positions in embedded fit with the middle supporting plate126are provided with the slots127. Various types of slots and openings are provided inside the middle supporting plate126for mounting of electronic components.

Slots129are provided in the portions of the coupling portion102in contact with the control compartment shell103and the detection head cover101for accommodating O-shaped rings. In the case of connection, part of walls of the coupling portion102extend into the detection head cover101and the special-shaped compartment104and fit tightly to achieve watertight mounting, and jackscrews111are provided in the fitted extending positions to achieve fixation of the two compartments without disengagement, and subsequent mounting of the compartments is also carried out in this way.

The special-shaped compartment104is connected to the control compartment shell103, and the contact portion is also grooved to accommodate an O-shaped ring. The special-shaped compartment104is provided with eight small tables, and the small tables132are designed in a concave manner for mounting of the watertight joints113, the depth sensor1140, and the switch115. Wires are led out through the watertight joints113to achieve waterproofing and quick disassembly and assembly. The watertight joints113are mounted on watertight seats133, and further, the watertight seats133are mounted on six small tables132on the special-shaped compartment104. One table131is left for mounting the watertight joint113and the switch114, and the table131is deeper than the table130. Similarly, the watertight joint113and the switch114are also mounted on the special-shaped compartment104by means of the watertight seat133.

The special-shaped compartment104is also in watertight connection with the control compartment cover105in the same way, with a watertight O-shaped ring134provided at the connecting portion. The control compartment cover105is concave in the middle for accommodating the male socket plug135to be connected to the battery compartment cover106. The battery compartment cover106is also provided with the same structure in the middle for accommodating the female socket plug136. A protruding portion in the middle of the battery compartment cover106may be embedded into the control compartment cover105during installation, and the depressions in the middle of the control compartment cover105and the battery compartment cover106are used for accommodating the male socket plug135and the female socket plug136, respectively. The battery compartment cover106is connected to the battery compartment shell107, also with an O-shaped ring137provided at the connecting portion. The battery platform138is provided inside the battery compartment, and the battery platform138is used for placement of the battery139. The battery platform138is connected to apertures145in the battery compartment cover106by means of copper posts144. The battery platform138includes a battery rack146, a wire EVA plate147, a battery flat plate supporting bracket148, a battery bending supporting bracket149, and a battery top plate150. The battery rack146is connected to the battery compartment cover106by means of the copper posts144. A hole in the middle of the battery rack146is used for the passage of a battery wire. The wire EVA plate147is placed on the battery rack146and used for leading out the battery wire. The battery bending supporting bracket149and the battery flat plate supporting bracket148are placed on the battery rack146and fixed by screws, and are used for limiting the movement of a battery in the radial direction. The battery top plate150is connected to tops of the battery bending supporting bracket149and the battery flat plate supporting bracket148to prevent the battery from moving in the axial direction.

The compartment cover transition section108is connected to the battery compartment shell107, with an O-shaped ring140and a jackscrew141provided at the connecting portion. The compartment cover transition section108is connected to a grip143.

The main body compartment1is connected to the shells by means of the head skeletons201, the middle skeletons202and the tail skeletons203. The head skeletons201, the middle skeletons202, and the tail skeletons203are symmetrically disposed on the left and right sides of the main body compartment1respectively, and are fixed to the coupling portion102on the main body compartment by screws. The head skeletons201, the middle skeletons202, and the tail skeletons203are connected to the streamlined shells206. The head skeletons201are coupled to a main control compartment and the streamlined shells206. The tail skeletons203are coupled to a power supply compartment and the low-flow resistance shell206. The shells are longitudinally provided with four brushless motor propellers207to provide lifting and lowering power, and transversely provided with four catheter propellers208in a vectorial manner, and wires thereof enter the special-shaped compartment104by means of the watertight joints113to drive the machine to achieve rapid movement, levitation, and other functions.

The main body of the robot is carried by an alloy lightweight handle204, and an existing expansion module, such as a DVL, a single-degree-of-freedom underwater robotic arm, a sonar, a binocular camera, and a laser rangefinder, is mounted through the reserved holes in the expansion skeleton205, and is connected for use through a watertight joint113reserved on the fuselage.

As an improvement to the above solution, referring toFIG.11toFIG.14, the underwater submersible robot further includes a mounting bottom plate410and at least two adaptive magnetization modules4. The mounting bottom plate410is used for being removably connected to the fuselage1, and the at least two adaptive magnetization modules4are connected to two sides of the mounting bottom plate410. Each of the adaptive magnetization modules4includes: a lifting plate401, a first small hydraulic rod402, a second small hydraulic rod403, a magnetization fixing module404, a bearing plate405, a second large hydraulic rod406, a first large hydraulic rod407, an adaptive adjustment holding mechanism408, and a bottom connecting skeleton409. An included angle formed by each of two sides of the bearing plate405and a middle position of the bearing plate405is an obtuse angle, and bottom sides of the two sides of the bearing plate405are each connected to the magnetization fixing module404by means of a plurality of sets of first small hydraulic rods402and second small hydraulic rods403. The first small hydraulic rods402are connected to the second small hydraulic rods403in a hydraulic driving manner, and are capable of making linear motion relative to the second large hydraulic rods406. Top sides of the two sides of the bearing plate405are each connected to the mounting bottom plate410by means of the second large hydraulic rods406and the first large hydraulic rods407, and the first large hydraulic rods are connected to the second large hydraulic rods in a hydraulic driving manner.

Specifically, the adaptive magnetization module4is mainly used for fixation and attraction and stable movement along a column, and at the same time, is capable of effectively counteracting the strong ocean current disturbance encountered during the detection process.

The bottom of the fuselage of the underwater submersible robot and an adaptive controllable magnetization climbing module are tightly connected through screws and fixing holes, and the mounting bottom plate410is affixed to the bottom of the fuselage of the underwater submersible robot, which effectively serves as a supporting and stabilizing role. The adaptive adjustment holding mechanism408adopts a tilted diversion mode, which effectively reduces the influence of water resistance during the operation of the equipment and reduces the excess energy loss while achieving stable connection. When the equipment identifies and detects surface crack diseases of the underwater engineering, and when the equipment is close to the underwater engineering, the underwater submersible robot may adjust the rotational speed and steering of each propeller in a targeted manner, so that the equipment operates in a vertical state. At the same time, under the propeller drive, the equipment moves gradually close to the surface crack diseases of the underwater engineering in the vertical state, in this case, the adaptive controllable magnetization climbing module mounted at the bottom of the equipment achieves rapid and repeated magnetization and demagnetization of the interior of the magnetization fixing module404mounted at a lower end of the bearing plate405in the case of short electrical pulses, resulting in a huge magnetic force. As steel reinforcement is densely distributed inside an underwater engineering supporting column, the magnetization fixing module404may be quickly and stably attached to the surface of the underwater engineering supporting column, so that the whole set of equipment is stably attached to the surface of the underwater engineering supporting column. When the equipment is attached to the surface of the underwater engineering supporting column, the propellers in the horizontal direction of the equipment may increase the rotational speed, in which case the equipment may autonomously detect the attraction situation of the adaptive controllable magnetization climbing module for a stability warning test. When the rated detection rotational speed is reached and the equipment is still able to be stably attracted on the surface of the underwater engineering supporting column, the rotational speed of the propellers may return to a normal value for movement along the column surface and disease detection in the next step. Meanwhile, in the process of attachment, the equipment may adjust the opening and closing of the bottom connecting skeleton409in real time according to the radius of the underwater engineering supporting column. When the underwater engineering supporting column is thick, the bottom connecting skeleton409may flip upwards to expand a fixing space in the middle, and effectively expand the climbing radius of the adaptive controllable magnetization climbing module, so that the magnetization fixing module404is better attached to the surface of the underwater engineering supporting column, the height adaptability of the magnetization climbing module is effectively improved, and the breadth of application of the module may be expanded in a targeted manner. At the same time, when the magnetization fixing module404is fixed to the surface of the underwater engineering supporting column, the lifting plate located in the middle may gradually descend, so that the magnetization fixing module404at the bottom of the lifting plate401is attached to the surface of the underwater engineering supporting column, and the first large hydraulic rods407and the second large hydraulic rods406located at the top of the lifting plate may be adjusted in real time to make the magnetization fixing module404be attached to the surface of the underwater engineering supporting column smoothly. After the equipment is stably attached to the surface of the underwater engineering supporting column, the plurality of propellers located on the surface of the robot stably provide forward and backward power for the adaptive controllable magnetization climbing module, so that the equipment may stably operate on the surface of the column to achieve the function of stably searching for crack diseases on the surface of the column. The first large hydraulic rods407and the second large hydraulic rods406located at the top of the lifting plate401may be adjusted in real time, and the buffer adjustment of the hydraulic rods mainly plays a role in stabilizing the adaptive controllable magnetization climbing module of the equipment and reducing the pressure on the surface of the underwater engineering supporting column, thereby effectively dispersing a transverse water pressure as well as a pressure on the surface of the underwater engineering supporting column caused by the weight thereof, and avoiding other damages and impacts on the surface of the supporting column. At the same time, the first small hydraulic rods402and the second small hydraulic rods403located at the lower end of the bearing plate405may be adjusted in time when the magnetization fixing module404is fixed. When the equipment is affected by the water flow impact during the fixing process, the small hydraulic rod module is conducive to real-time adjustment and buffering to effectively reduce the influence and damage of the water flow impact on the whole equipment, and is also conducive to the establishment of a stable detection environment for the equipment to stably carry out disease detection at the crack disease position. When the equipment needs micro-angle steering adjustment, the magnetization fixing module404may reduce the magnetic force to produce a small gap between the module and the surface of the underwater engineering supporting column, the propellers of the equipment may be adjusted in time to achieve turning adjustment of the main engine, and after the equipment is adjusted, the magnetization fixing module404may increase the intensity of short electrical pulses to greatly increase the maximum magnetic force, so that the equipment may be rapidly attracted on the surface of the underwater engineering supporting column again to complete the turning adjustment of any micro angle during operation, thereby achieving the accuracy and pertinence of a disease detection site, and effectively improving the accuracy and reliability of underwater engineering disease detection.

FIG.13shows an operational flow diagram of the adaptive controllable magnetization climbing module. The operational process of the adaptive controllable magnetization climbing module is divided into a macro-angle adjustment module, a hydraulic clamping module, and short electrical pulse triggering. During the operation of the adaptive controllable magnetization climbing module, the macro-angle adjustment module adjusts the position of the equipment at a large angle; in this case, the hydraulic clamping module synchronously carries out multi-stage adjustment, to effectively achieve an attraction and fixation angle under the multi-stage reaction of a large and small hydraulic rod adjustment module, and at the same time, may achieve rapid adaptive adjustment; and under the short electrical pulse triggering at the bottom, the magnetization fixing module at the lower end effectively achieves the effect of magnetic tight attraction and fixation through rapid and repeated magnetization and demagnetization, and finally, adaptive rapid and stable attraction and fixation are achieved. When an identification module operates, the magnetization fixing module is in an operating state, so that the equipment is firmly fixed on the surface of the underwater engineering supporting column, allowing the equipment to be fixed in a stable detection environment. In this case, the ultra definition camera121recognizes underwater engineering diseases under the machine, and may transmit images back rapidly. When the detection is completed, the equipment may rapidly respond to search for the next disease site.

As an improvement to the above solution, referring toFIG.9andFIG.10, the underwater submersible robot further includes two pairs of motion assisting modules3disposed on the two sides of the fuselage1. Each of the motion assisting modules3includes a fixing support301, a motor302, and a spoiler303, where the fixing support301is disposed on one side of the fuselage1, the spoiler303is disposed on the fixing support301in a manner of rotating up and down, and the motor302is disposed on the fuselage1and used for driving the spoiler303to move up and down.

Specifically, when the equipment (i.e., the underwater submersible robot) operates underwater, the motion assisting modules maintain a standby state at all times. When the equipment needs to brake quickly during operation, the motor302mounted on the fixing support301operates synchronously while the propellers decelerate and thrust reversely, and the spoiler303located around the fuselage is unfolded outward along the fuselage under the drive of the motor302, to expand the area of water resistance and increase the running resistance of the equipment, so that the operation speed of the equipment decreases rapidly, and the function of rapid mechanical risk avoidance is achieved. When the equipment needs to make a quick turn, in the case that the equipment turns sharply to the right, the spoiler303on the side is quickly started while the operation speed of the propellers is adjusted, the flow rate of the right side instantly increases under the action of the spoiler303, the pressure is rapidly reduced, and the fuselage of the equipment may also quickly turn to the right under the drive of the difference in pressure, so that the equipment may quickly turn to avoid danger under the combined action of the spoiler303and the propellers. The same is true for the sharp turn to the left side, thereby achieving the highly sensitive movement of the underwater submersible robot.

As an improvement to the above solution, referring toFIG.15toFIG.18, the detection apparatus2includes an underwater vision matrix module5. The underwater vision matrix module5includes: a matrix collar503and at least two camera adjustment assemblies. The matrix collar503is used for being removably mounted on the fuselage1. The at least two camera adjustment assemblies are uniformly distributed on the same side of the matrix collar503. Each of the camera adjustment assemblies includes: linear actuators501, a clamping plate502, a waterproof motor504, a waterproof camera505, a motion frame506, and a hinged motion frame507, where a bottom end of the hinged motion frame507is hinged to the matrix collar503, a top end of the hinged motion frame507is provided with the waterproof motor504, a free end of a rotating shaft of the waterproof motor504is provided with the waterproof camera505, one end of the clamping plate502is connected to a middle position of the hinged motion frame507, the other end of the clamping plate502is connected to one end of the motion frame506, the other end of the motion frame506is connected to one end of the clamping plate502of another camera adjustment assembly, the other end of the clamping plate502of another camera adjustment assembly is connected to the middle position of the hinged motion frame507of the camera adjustment assembly, the linear actuators501are disposed on the matrix collar503, and a free end of a push rod of each linear actuator501is connected to a middle position of the motion frame506.

Specifically, the underwater vision matrix module5is configured to acquire a high-quality data set and a larger field of view.

When the equipment identifies and detects crack diseases on the surface of the underwater engineering, and when the equipment is close to the underwater engineering, the linear actuators501located at the upper and lower ends are activated according to the distance between the equipment and the detection target, so as to push the motion frame506to move forward, and while the motion frame506moves forward, the hinged motion frame507which is connected to the motion frame506through the clamping plate502also moves forward to be gradually close to the detection target. When the hinged motion frame507moves to be close to the detection target, the waterproof motor504located at the tail end of the hinged motion frame507is started, and the waterproof motor504rotates in combination with the distance and angle relationship between the waterproof camera505and the detection target, so as to drive the waterproof camera505to rotate synchronously, so that the field of view of the waterproof camera505surrounds the detection target in all directions for detection, thereby improving the detection coverage and accuracy, also effectively expanding the detection field of view and increasing the detection speed, and greatly improving the operation efficiency and detection accuracy.

FIG.16andFIG.17show a bionic compound eye based underwater matrix module and an operational flow diagram of an algorithm thereof. The bionic compound eye based underwater matrix module acquires relevant position and distance information after position and distance recognition and sensing, which serves as a condition for the operation of a pose adjustment module, and the module drives a linear actuator adjustment module and a small waterproof motor angle adjustment module to accurately adjust and change the pose of the equipment, so as to achieve rapid adaptive adjustment and switching for the optimal disease modeling position. During adjustment, an image acquisition and recognition module located at the front end integrates the visual enhancement algorithm and feature fusion to construct an accurate disease recognition system, so as to achieve rapid and accurate recognition and identification of underwater engineering diseases. At the same time, according to the required use, the equipment may be subjected to multi-module expansion switching, including underwater exploration and water body detection modules and other exploration modules, and ultimately the omni-directional full-coverage high-accuracy target recognition and detection of underwater engineering diseases are effectively achieved. A feature fusion module is responsible for splicing collected omni-directional target images into a target image with more comprehensive and obvious features, and the module includes five operations: preprocessing, feature extraction, feature matching, image alignment, and image fusion. Images taken underwater may have scattering, color distortion and other phenomena, for which pre-processing is required before feature fusion, including color correction and scattering removal. With regard to color correction, histogram equalization is used to improve the color accuracy of the images, which makes the features of the original gray images more obvious. With regard to scattering removal, wavelet denoising is used to reduce the influence of scattering in the underwater environment, taking into account scattering noise and background noise contained in the images. The feature extraction operation aims to extract features from each image, where key points with scale invariance and rotation invariance are extracted using the SIFT algorithm, and corresponding descriptors are generated. After obtaining the descriptors of the features, feature matching of the images is carried out, and a descriptor-based least squares algorithm is used to find the corresponding relationship between these features, so as to determine the relative positions and attitudes of the features. After determining the relative information of the features, image alignment is carried out, and on the basis of results of matching, an affine transformation model is used to align the images. Finally, the aligned features are subjected to image fusion: after alignment of the image features, the pixel-level fusion method of weighted averaging is used for image fusion, and then the mean smoothing method is used to reduce the obvious excessive edges at the splicing position to further improve the quality of the image.

As an improvement to the above solution, referring toFIG.19toFIG.22, the underwater submersible robot further includes variable stiffness flexible hoop self-stabilizing modules6. The variable stiffness flexible hoop self-stabilizing module6includes a main fixing frame601, a pair of hydraulic mechanical claws60, variable stiffness cladding arrays607, gap-filling cladding inflatable units, and carbon fiber interlayers609. The main fixing frame601is used for being removably connected to the fuselage1. The pair of hydraulic mechanical claws60are disposed on two sides of the main fixing frame601respectively in a manner of moving close to or away from each other. The variable stiffness cladding arrays607are disposed on two sides of free ends of inner sides of the pair of hydraulic mechanical claws60. The gap-filling cladding inflatable units are disposed in middle positions of the inner sides of the pair of hydraulic mechanical claws60. The gap-filling cladding inflatable units are covered with the carbon fiber interlayers609.

Specifically, the variable stiffness flexible hoop self-stabilizing modules6are used for efficient detection of pile foundation type diseases and counteraction against ocean current disturbance.

The variable stiffness flexible hoop self-stabilizing module6is mounted on the detection head cover101of the main body compartment1. The hydraulic mechanical claws60are connected and fixed to the detection head cover101through the main fixing frame601. The detection head cover101is provided with clamping bosses151, and four clamping bosses151are distributed along the circumference and provided with holes150, and fix the main fixing frame601through screws. The main fixing frame601is connected to the hydraulic mechanical claws60. The hydraulic mechanical claw60includes a front hydraulic component603, a rear hydraulic component604, a mechanical claw front section602, a mechanical claw middle section605, and a mechanical claw tail section606. During operation, the front hydraulic component603extends out firstly, and then the rear hydraulic component604extends out to drive the mechanical claw front section602, the mechanical claw middle section605, and the mechanical claw tail section606of the hoop self-stabilizing module6to be closed. After a mechanical claw body wraps an object, the carbon fiber interlayer609located in the middle portion may be in contact with the surface of the target object to play a supporting role. After stabilization is achieved, the interior of the gap-filling cladding units608is filled with air under the drive of a gear air pump, in which process the surfaces of the gap-filling cladding units608may be in close contact with the target object to achieve flexible full-coverage attachment to the surface of the target object to improve attachment stability. After the gap-filling cladding units608complete the first level of attachment, the variable stiffness cladding arrays607carry out secondary flexible attachment operation, and the variable stiffness cladding arrays may be further attached to the surface of the target object to improve the rigidity of a cladding contact surface. By means of the multi-level attachment, the stability of the equipment for grasping the object is greatly improved. Two variable stiffness flexible hoop self-stabilizing modules6are provided in total, distributed at the front end of the machine, and may pick up large underwater objects in any shape in a non-destructive manner to complete the sampling operation. In addition to the non-destructive sampling function, in the implementation of underwater engineering disease detection work, in order to prevent ocean currents from disturbing the robot to result in poor imaging quality at the diseases, the mechanical claws are driven by the hydraulic components604to hoop an underwater pile foundation, and the gap-filling cladding units608and the variable stiffness cladding arrays607are used for achieving a non-destructive tight hoop for the surface of the pile foundation, thereby achieving stable imaging of the fuselage.

During operation, after the variable stiffness flexible hoop self-stabilizing modules6hoop a designated pile foundation, the battery139supplies power, the ultra definition camera121recognizes images in front of the machine and may transmit the images back, the brushless motor propellers operate to achieve vertical movement of the machine to the disease position, and then the ultra definition camera121carries out the detection operation, thereby obtaining a high-quality pile foundation damage dataset.

FIG.21shows a schematic operational logic diagram of the variable stiffness flexible hoop self-stabilizing module. Position and distance information collection at the front end achieves information supply for a control center. The hydraulic mechanical claws are made of rigid high-strength composite materials, and effectively resist the harsh operating environment underwater. At the same time, the hydraulic rod system carries out targeted adjustment on the opening and closing amplitude and size of the hydraulic mechanical claws, to achieve adaptive adjustment for the target object, and achieve rapid and stable grasp of the fuselage portion of the target object. During operation of the hydraulic mechanical claws, the gap-filling cladding units operate synchronously, and the interior of the units is filled with air under the action of the gear air pump according to data fed back by a pressure sensor, so as to achieve full-angle flexible attached grasp of the target object. At the same time, the variable stiffness cladding arrays carry out targeted filling on the remaining gaps, so that the inner sides of the hydraulic mechanical claws fully cover the surface of the target object, thereby achieving micro-angle gap fit cladding, and ultimately achieving full-angle flexible cladding grasp.

FIG.23andFIG.25are schematic flow diagrams of a control method for an underwater submersible robot according to an embodiment of the present invention. The control method for the underwater submersible robot is implemented by the control apparatus9for the underwater submersible robot. The method applied to the underwater submersible robot according to any one of the embodiments described above includes steps S10to S14:S10: Calculate a first difference between a current actual attitude of a fuselage and a desired attitude and a second difference between an actual depth and a desired depth.S11: Input the first difference and the second difference into a set terminal sliding mode surface to obtain an output value of the terminal sliding mode surface.S12: Use the output value as an input of a preset high-order observer, a radial basis function neural network and a terminal sliding mode control law, respectively, and use an output of the high-order observer and an output of the radial basis function neural network as a compensation input of the terminal sliding mode control law to obtain a virtual force outputted by the terminal sliding mode control law.S13: Perform power distribution for each propeller of a propeller assembly on the basis of the virtual force to obtain a propelling force of each propeller.S14: Control a propelling operation of the propellers on the basis of the propelling force.

In the embodiment of the present invention, the first difference between the current actual attitude of the fuselage and the desired attitude and the second difference between the actual depth and the desired depth are calculated; the first difference and the second difference are inputted into the set terminal sliding mode surface to obtain the output value of the terminal sliding mode surface; the output value is used as the input of the preset high-order observer, the radial basis function neural network, and the terminal sliding mode control law, respectively, and the output of the high-order observer and the output of the radial basis function neural network are used as the compensation input of the terminal sliding mode control law, so that a data deviation may be compensated for the current underwater turbulence, and the terminal sliding mode control law may ultimately output a more accurate virtual force; power distribution is carried out for each propeller of the propeller assembly on the basis of the virtual force to obtain the propelling force of each propeller; the propellers of the underwater submersible robot are controlled to operate on the basis of the propelling force. Thus, more reasonable motion control may be carried out for the current underwater disturbance. It can be seen that the embodiment of the present invention may improve the anti-disturbance capacity of the underwater submersible robot against underwater turbulence, so as to achieve the autonomous fuselage stabilization under the complex environment and the autonomous extrication operation under the emergency environment, which effectively achieves the autonomous strong anti-disturbance function, improves the operation safety and stability of the equipment, and reduces the occurrence probability of accidents of the equipment. Moreover, based on the control strategy, the intelligent operation of the underwater unmanned aerial vehicle is achieved, the efficiency of underwater engineering detection is substantially improved, the safety of underwater engineering detection work is effectively improved, the need for divers to directly participate in the operation is eliminated, and the risk faced by the staff when operating in the underwater environment is greatly reduced.

As an improvement on the above solution, the performing power distribution for each propeller of a propeller assembly on the basis of the virtual force to obtain a propelling force of each propeller includes:filtering the virtual force using a second-order filter, and converting the filtered virtual force into the propelling force of each propeller of the propeller assembly by power distribution.

It is to be noted that the relevant solution contents of the above-described embodiment of the control method for the underwater submersible robot may correspondingly refer to the solution contents of the above-described embodiment of the control apparatus9for the underwater submersible robot, which will not be repeated herein.

FIG.26is a schematic diagram of a control apparatus9for an underwater submersible robot according to an embodiment of the present invention. The control apparatus9for the underwater submersible robot according to this embodiment includes: a processor1000, a memory1001, and a computer program stored in the memory1001and runnable on the processor1000, for example, a control program for the underwater submersible robot. The processor1000, when executing the computer program, implements the steps in the above-described embodiments of the control method for the underwater submersible robot.

Exemplarily, the computer program may be partitioned into one or more modules/units, and the one or more modules/units are stored in the memory and executed by the processor to implement the present invention. The one or more module/units may be a series of computer program instruction segments capable of accomplishing a particular function, and the instruction segments are used to describe the execution process of the computer program in the control apparatus9for the underwater submersible robot.

The control apparatus9for the underwater submersible robot may include, but is not limited to, a processor and a memory. A person skilled in the art may appreciate that the schematic diagrams are merely examples of the control apparatus9for the underwater submersible robot and do not constitute a limitation on the control apparatus9for the underwater submersible robot. The control apparatus may include more or less components than shown, or a combination of some components, or different components. For example, the control apparatus9for the underwater submersible robot may also include input and output devices, network access devices, buses, etc.

The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and so on. The general-purpose processors may be microprocessors or any conventional processor, etc. The processor is a control center of the control apparatus9for the underwater submersible robot, and is connected to each part of the entire control apparatus9for the underwater submersible robot via various interfaces and lines.

The memory may be used for storing the computer program and/or modules, and the processor implements various functions of the control apparatus9for the underwater submersible robot by running or executing the computer program and/or modules stored in the memory and invoking data stored in the memory. The memory may mainly include a program storage region and a data storage region. The program storage region may store applications required for an operating system and at least one function. The data storage region may store data created according to the use of a mobile phone. In addition, the memory may include a high-speed random access memory, or a non-volatile memory, such as a hard disk, an internal memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a Flash card, at least one disk memory device, a flash memory device, or other volatile solid-state memory devices.

The modules/units integrated on the control apparatus9for the underwater submersible robot, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the present invention may also implement all or part of the processes of the method in the above embodiment by instructing relevant hardware by means of a computer program. The computer program may be stored in a computer-readable storage medium, and the computer program, when executed by a processor, may implement the steps of the method embodiments described above. The computer program includes a computer program code, and the computer program code may be in a form of source code, object code, executable file or some intermediate forms. The computer-readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a mobile hard disk drive, a diskette, a compact disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It is to be noted that the computer-readable medium may contain content which is subject to appropriate additions and subtractions as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, the computer-readable medium does not include the electrical carrier signal or the telecommunication signal in accordance with legislation and patent practice.

It is to be noted that the apparatus embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or distributed to multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solutions of the embodiments. In addition, in the accompanying drawings of the apparatus embodiments provided by the present invention, the connection relationship between the modules indicates that they have a communication connection therebetween, which may be specifically implemented as one or more communication buses or signal lines. Those of ordinary skill in the art can understand and implement it without creative work.

While the foregoing is directed to the preferred embodiments of the present invention, it should be noted that several improvements and modifications can be made by persons of ordinary skill in the art without departing from the principle of the present invention, and such improvements and modifications shall also fall within the scope of protection of the present invention.