Ocean platform output feedback vibration reduction control method

Abstract

The invention discloses an ocean platform output feedback vibration reduction control method which comprises the following steps: obtaining a state feedback vibration reduction control law according to an ocean platform motion model; designing a high-gain observer according to the ocean platform motion model, and obtaining an estimation state of the high-gain observer; according to the estimation state of the high-gain observer, an output feedback vibration reduction control law is obtained; determining the saturation degree of the saturation output feedback vibration reduction control law according to the maximum value of the state feedback vibration reduction control law; obtaining a saturation output feedback vibration reduction control law according to the output feedback vibration reduction control law; and an output feedback vibration reduction control law meeting the requirement is obtained. All platform state data do not need to be directly obtained, the practicability of the control method is improved, effective control over vibration reduction of the ocean platform is achieved, meanwhile, an external system model or an internal model does not need to be established, and the application range of the control method is widened. The gain of the high-gain observer can overcome the factors of external interference and modeling errors of the system, and the stability and adaptability of ocean platform control are ensured.

Description

Technical Field

[0001] The present invention relates to the field of marine engineering technology, and more specifically, to an output feedback vibration reduction control method for an offshore platform. Background Art

[0002] The offshore platform works in a near-shore environment. Its geographical location and working environment can easily cause the sensor to be damaged, so the signal cannot be transmitted correctly, resulting in the state feedback controller being unable to obtain the required information. Therefore, it is particularly important to study the output feedback control for reasons such as sensor damage. At the same time, the offshore platform is disturbed by various factors such as wind and waves, and the modeling process of its vibration reduction system is affected by many interference factors, which makes the established model contain uncertainties.

[0003] At present, the vibration reduction control method for offshore platforms is generally designed to be state feedback control, that is, based on the ideal situation that all sensors are working properly. The general state feedback vibration reduction control method is as follows:

[0004] γ(t)=Φ(ξ,t)

[0005] Among them, γ(t) is the control force input to the platform at time t, ξ(t) is the displacement and velocity of the platform, and Φ is the function.

[0006] It can be seen that the implementation of the above control law requires sensors to collect data from all platforms in real time. Once a sensor is damaged, aged or limited, the data cannot be obtained or the data obtained is inaccurate, which will cause the controller to fail or become difficult to implement.

[0007] In addition, the existing offshore platform output feedback control does not take into account the uncertainties in the model, resulting in large modeling errors and poor controller implementation effects. Summary of the invention

[0008] The object of the present invention is to provide an output feedback vibration reduction control method for an offshore platform which can solve the problem of large modeling errors and improve the applicability and control effect.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows: an output feedback vibration reduction control method for an offshore platform, comprising the following steps:

[0010] S1. According to the motion model of the offshore platform, the state feedback vibration reduction control law γ(t) = Φ(ξ, t) is obtained;

[0011] S2. Design a high-gain observer based on the ocean platform motion model and obtain the estimated state of the high-gain observer

[0012] S3. According to the estimated state of the high-gain observer, the output feedback vibration reduction control law is obtained

[0013] S4. Determine the saturation M of the saturated output feedback vibration reduction control law according to the maximum value of the state feedback vibration reduction control law;

[0014] S5. According to the output feedback vibration reduction control law, the saturated output feedback vibration reduction control law is obtained.

[0015]

[0016] Among them, sat(·) represents the saturation function and M is the saturation degree.

[0017] S6. Design the gains β1, β2 and parameter μ of the high-gain observer that meet the stability conditions and obtain the output feedback vibration reduction control law that meets the requirements.

[0018] Preferably, in step S1, the ocean platform motion model equation is:

[0019]

[0020]

[0021] Among them, ξ is the platform state vector, including the displacement and velocity of the platform, γ is the control force applied to the platform, d is the wave force exerted on the platform, ζ is the output vector of the system, and E, F, G, and D are coefficient matrices of corresponding dimensions respectively.

[0022] Preferably, the state feedback vibration reduction control law in step S1 is:

[0023] γ(t)=Φ(ξ,t)

[0024] Among them, Φ(ξ,t)=-[l1ξ1(t)+l2ξ2(t)+d(t)] is the feedback linearization vibration reduction control law, l1,l2∈R are the controller gains, and the closed-loop system matrix is ​​made by the pole configuration method. For Hurwitz.

[0025] Preferably, in step S2, a high-gain observer is designed according to the ocean platform motion model equation:

[0026]

[0027]

[0028] Where N = [β1 / μ,L,β n / μ n ] is the gain matrix of the high-gain observer, where β iis the high gain observer gain, μ∈(0,1) is the high gain observer parameter, is the state vector of the high-gain observer, is the output vector of the high gain observer, d0(t) is the nominal function, that is, the wave force d in the original system is allowed to have modeling errors.

[0029] Preferably, in step S3, the state generated by the high-gain observer replaces the state in the state feedback vibration reduction control law, that is, the output feedback vibration reduction control law is obtained as:

[0030]

[0031] Preferably, in step S4, the saturation M of the saturated output feedback vibration reduction control law is determined according to the maximum value of the state feedback vibration reduction control law, that is,

[0032] M = maxγ(t).

[0033] Preferably, in step S5, the output feedback vibration damping control law is saturated according to the saturation obtained by the state feedback vibration damping control law, that is, a saturated output feedback vibration damping control law is obtained:

[0034]

[0035] Preferably, in step S6, the gain β of the high-gain observer is designed to meet the stability condition. i And parameter μ, the specific process is as follows:

[0036] A1. Use pole placement to design the gain β of a high-gain observer i , so that the equation λ n +β1λ+L+β n = 0 all have negative real parts;

[0037] A2. Adjust the parameter μ∈(0,1) of the high-gain observer so that the closed-loop system state under the high-gain observer is asymptotically stable.

[0038] Compared with the prior art, the advantages of the present invention are:

[0039] 1. The present invention does not need to directly obtain all platform state data (displacement and speed), which improves the practicability of the control method. Compared with the existing control method that requires all state variables, the present invention can be applied to systems that only obtain part of the state variables (displacement or speed) to achieve effective control of marine platform vibration reduction.

[0040] 2. The present invention does not need to establish an external system model or an internal model, which broadens the scope of application of the control method. Compared with the existing vibration reduction control algorithm that requires accurate interference information to establish an external system or an internal model, the high-gain observer gain in the control of the present invention can overcome the factors of external interference and system modeling errors, ensuring the stability and adaptability of the control of the marine platform.

[0041] 3. The form of the vibration reduction control law of the present invention covers linear vibration reduction control or nonlinear vibration reduction control, and can be applied to other control scenarios besides the present invention, and has good scalability for a wider range of application models and more stringent control requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 is the characteristic parameter of the offshore platform;

[0044] Figure 2 This is a numerical simulation diagram of the vibration reduction displacement response of the marine platform of the present invention;

[0045] Figure 3 This is the numerical simulation diagram of the vibration reduction speed response of the marine platform of the present invention. DETAILED DESCRIPTION

[0046] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0047] The present embodiment discloses an output feedback vibration reduction control method for an offshore platform, comprising the following steps:

[0048] S1. According to the motion model of the offshore platform, the feedback linearization state feedback vibration reduction control law γ(t) is obtained;

[0049] S2. Design a high-gain observer based on the ocean platform motion model and obtain the estimated state of the high-gain observer

[0050] S3. Based on the estimated state of the high-gain observer, the output feedback vibration reduction control law is obtained

[0051] S4. Determine the saturation M of the saturated output feedback vibration reduction control law according to the maximum value of the state feedback vibration reduction control law;

[0052] S5. According to the output feedback vibration reduction control law, the saturated output feedback vibration reduction control law γ is obtained. sat (t);

[0053] S6. Design the gains β1, β2 and parameter μ of the high-gain observer that meet the stability conditions and obtain the output feedback vibration reduction control law.

[0054] Specifically, according to Figure 1 The structural parameters of the ocean platform are shown, and a simplified model of the ocean platform motion is obtained.

[0055] The motion model equation of the offshore platform is:

[0056]

[0057] Among them, ξ is the platform state vector, including the platform's displacement and velocity, Φ is the control force applied to the platform, and d is the wave force on the platform. is the output vector of the system, where E, F, G, and D are the following coefficient matrices:

[0058]

[0059] The parameter meanings and parameter values ​​are shown in Table 1.

[0060] The feedback linearization state feedback vibration reduction control law is designed for the offshore platform motion model (1):

[0061] γ(t)=-[l1ξ1(t)+l2ξ2(t)+d(t)] (2)

[0062] Among them, l1,l2∈R are controller gains, and the closed-loop system matrix is ​​made by pole placement method. For Hurwitz.

[0063] According to the ocean platform motion model (1), a high-gain observer is designed:

[0064]

[0065] Where N = [β1 / μ,β2 / μ 2 ] is the gain matrix of the high-gain observer, β1, β2 are the gains of the high-gain observer, μ∈(0,1) is the parameter of the high-gain observer, is the state vector of the high-gain observer, is the output vector of the high gain observer, and d0 is the nominal function.

[0066] The state of the high gain observer (3) Replacing the states ξ1(t) and ξ2(t) in the state feedback vibration damping control law (2), we get the output feedback vibration damping control law:

[0067]

[0068] The saturation of the saturated output feedback vibration reduction control law is determined according to the maximum value of the state feedback vibration reduction control law (2):

[0069] M=maxγ(t) (5)

[0070] The saturation degree obtained in (5) is used to saturate the output feedback vibration reduction control law (4) to obtain the saturated output feedback vibration reduction control law:

[0071]

[0072] The process of designing the gains β1, β2 and parameter μ of a high-gain observer that satisfies the stability condition is as follows:

[0073] A1. Use the pole placement method to design the gains β1, β2 of the high-gain observer so that the quadratic equation λ 2 The roots of +β1λ+β2=0 all have negative real parts;

[0074] A2. Adjust the parameter μ∈(0,1) of the high-gain observer so that the closed-loop system state under the high-gain observer is asymptotically stable.

[0075] like Figure 1 Offshore platform with parameter values ​​shown in .

[0076] like Figure 2 , Figure 3 As shown, the state feedback vibration reduction control law (2) and the output feedback vibration reduction control law (6) are used as vibration reduction controllers of the offshore platform, and numerical simulation is performed using MATLAB.

[0077] At this time, the controller gains obtained by pole placement method are l1 = 4,451,740, l2 = 7,046,909. Applying the state feedback vibration reduction controller (2) to the offshore platform, we get Figure 2 and Figure 3 The displacement and velocity responses are shown in the solid line. However, considering that it is difficult to measure the velocity of the offshore platform through sensors in practical applications, and there may be modeling errors in the offshore platform motion model (1), in these cases, the state feedback vibration reduction control law (2) will fail. In these cases, a high-gain observer (3) and its output feedback vibration reduction control law (4) are designed. According to (5), M = 5 × 10 6, thus obtaining the saturated output feedback vibration reduction controller (6), selecting β1 = 2, β2 = 1, and selecting the parameters μ = 0.01, 0.02 of the high gain observer respectively, applying the vibration reduction controller to the offshore platform, and obtaining Figure 2 and Figure 3 The displacement and velocity responses shown by the two dashed lines in the figure indicate that the output feedback vibration reduction controller designed for the offshore platform is effective.

[0078] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, the patent owner may make various variations or modifications within the scope of the appended claims. As long as they do not exceed the protection scope described in the claims of the present invention, they should be within the protection scope of the present invention.

Claims

1. An output feedback vibration reduction control method for an offshore platform, characterized in that: The following steps are involved: S1. According to the motion model of the offshore platform, the state feedback vibration reduction control law γ(t) = Φ(ξ, t) is obtained; S2. Design a high-gain observer based on the ocean platform motion model and obtain the estimated state of the high-gain observer S3. According to the estimated state of the high-gain observer, the output feedback vibration reduction control law is obtained S4. Determine the saturation M of the saturated output feedback vibration reduction control law according to the maximum value of the state feedback vibration reduction control law; S5. According to the output feedback vibration reduction control law, the saturated output feedback vibration reduction control law is obtained. Among them, sat(·) represents the saturation function and M is the saturation degree. S6. Design the gains β1, β2 and parameter μ of the high-gain observer that meet the stability conditions and obtain the output feedback vibration reduction control law that meets the requirements.

2. The offshore platform output feedback vibration reduction control method according to claim 1, characterized in that: In step S1, the ocean platform motion model equation is: Among them, ξ is the platform state vector, including the platform's displacement and velocity, γ is the control force applied to the platform, and d is the wave force on the platform. is the output vector of the system, and E, F, G, and D are coefficient matrices of corresponding dimensions respectively.

3. The method for controlling vibration reduction of an offshore platform according to claim 2, characterized in that: The state feedback vibration reduction control law in step S1 is: γ(t)=Φ(ξ,t) Among them, Φ(ξ,t)=-[l1ξ1(t)+l2ξ2(t)+d(t)] is the feedback linearization vibration reduction control law, l1,l2∈R are the controller gains, and the closed-loop system matrix is ​​made by the pole configuration method. For Hurwitz.

4. The method for controlling vibration reduction of an offshore platform according to claim 2, characterized in that: In step S2, a high-gain observer is designed according to the ocean platform motion model equation: Where N = [β1 / μ,L,β n / μ n ] is the gain matrix of the high-gain observer, where β i is the high gain observer gain, μ∈(0,1) is the high gain observer parameter, is the state vector of the high-gain observer, is the output vector of the high gain observer, d0(t) is the nominal function, that is, the wave force d in the original system is allowed to have modeling errors.

5. The offshore platform output feedback vibration reduction control method according to claim 3, characterized in that: In step S3, the state generated by the high-gain observer replaces the state in the state feedback vibration reduction control law, that is, the output feedback vibration reduction control law is obtained as:

6. The method for controlling vibration reduction of an offshore platform according to claim 5, characterized in that: In step S4, the saturation M of the saturated output feedback vibration reduction control law is determined according to the maximum value of the state feedback vibration reduction control law, that is, M = maxγ(t).

7. The method for controlling vibration reduction of an offshore platform according to claim 6, characterized in that: In step S5, the output feedback vibration damping control law is saturated according to the saturation obtained by the state feedback vibration damping control law, that is, the saturated output feedback vibration damping control law is obtained:

8. The method for controlling vibration reduction of an offshore platform output feedback according to claim 4, characterized in that: In step S6, the gain β of the high-gain observer that satisfies the stability condition is designed. i And parameter μ, the specific process is as follows: A1. Use pole placement to design the gain β of a high-gain observer i , so that the equation λ n +β1λ+L+β n = 0 all have negative real parts; A2. Adjust the parameter μ∈(0,1) of the high-gain observer so that the closed-loop system state under the high-gain observer is asymptotically stable.

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