Anti-swing nonlinear control method and system based on variable frequency driver

Abstract

The invention provides an anti-swing nonlinear control method and system based on a variable frequency driver, and relates to the technical field of ocean engineering equipment.The method comprises the steps that obtained system parameters of an offshore crane system are input into a nonlinear disturbance observer, and an aggregation disturbance observation value output by the nonlinear disturbance observer is obtained; determining mechanical energy, a state error vector and an anti-swing parameter of the offshore crane system based on the system parameters; processing the mechanical energy, the state error vector and the anti-swing parameter by using an energy storage function to obtain virtual energy; and inputting the aggregated disturbance observation value, the mechanical energy, the state error vector and the anti-swing parameter into a nonlinear anti-swing controller to obtain a control parameter which is output by the nonlinear anti-swing controller and corresponds to the virtual energy, so that the offshore crane system executes the control parameter. According to the invention, high-precision positioning of the load can be ensured, and swinging can be effectively inhibited.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of offshore engineering equipment, and particularly relates to a swing prevention nonlinear control method and system based on a variable frequency driver. BACKGROUND

[0002] Offshore engineering equipment is widely used in the field of offshore engineering, such as shipwreck salvage, resource exploration and installation and maintenance. Due to its under-actuated characteristics (low control input dimension relative to state variable dimension) and complex dynamic disturbances in the marine environment (such as six-degree-of-freedom motion caused by sea waves and ocean currents), offshore engineering equipment faces major challenges in achieving precise load positioning and swing suppression. Traditional land engineering equipment needs to implement related swing prevention control methods through integrated variable frequency drives with motion control functions. Since the base motion in the marine environment introduces time-varying inertia force, Coriolis force and centrifugal force, the system dynamics are complex and difficult to model, so it is often difficult to be directly applied to offshore engineering equipment. In addition, unmodeled dynamics (such as friction force, parameter time variation) and unknown disturbances (such as random waves, sudden ocean currents) further increase the control difficulty, which may lead to actuator saturation and control performance degradation. The current solutions are as follows:

[0003] Feedback linearization control method, which linearizes part of the nonlinear system, combines proportional-differential (PD) control or other feedback mechanisms to achieve load positioning and swing suppression. The core idea is to simplify the complex nonlinear dynamics into a linear system to facilitate the design of variable frequency controllers, and adjust the system state through feedback mechanisms to achieve the target position and suppress swing. However, the feedback linearization method usually ignores important nonlinear terms, and fails to fully utilize the coupled nonlinear characteristics of offshore engineering equipment, resulting in limited control effect of the driver.

[0004] Sliding mode control method, sliding mode control designs a sliding surface, and makes the system state slide along the surface to the target state, thereby achieving robust control of system uncertainties and external disturbances. The core is to use a switching control law to force the system state to converge, even in the presence of disturbances, the control effect can be maintained. However, the switching term in the sliding mode control may cause high-frequency chattering, leading to actuator wear or system instability. In addition, the sliding surface parameter adjustment is difficult, especially in complex marine environments, parameter tuning requires a large number of tests, increasing the design cost. For non-stationary and high-frequency disturbances, the robustness of sliding mode control may be insufficient, resulting in a decrease in control accuracy or the inability to effectively suppress residual swing.

[0005] The control method of the driver based on the disturbance observer estimates the unmodeled dynamics (such as friction) and external disturbances (such as sea waves and wind) in the system in real time by designing a disturbance observer, and offsets the influence of these disturbances through feedforward compensation, thereby improving the control robustness. However, the existing disturbance observer usually assumes that the disturbance is bounded and low-frequency, while the random waves and sudden ocean currents in the marine environment have strong nonlinearity and high-frequency characteristics, which leads to a decrease in the estimation accuracy of the observer and limits the compensation effect.

[0006] The above methods all have significant limitations. The feedback linearization method is highly dependent on model accuracy and is difficult to deal with complex nonlinear disturbances; the sliding mode control has strong robustness, but the chattering problem and parameter adjustment difficulty limit its application; the disturbance observer method can compensate for disturbances, but it has insufficient processing capability for high-frequency and non-stationary disturbances, and does not fully consider the actuator saturation problem; therefore, the above methods cannot achieve high-precision positioning and effectively eliminate the swing. SUMMARY

[0007] In view of the deficiencies of the prior art, the purpose of the embodiments of the present application is to provide a variable frequency driver based anti-swing nonlinear control method, which can solve the technical problems of low positioning accuracy and ineffective swing elimination in the prior art.

[0008] In a first aspect of the embodiments of the present application, a variable frequency driver based anti-swing nonlinear control method is provided, comprising:

[0009] The system parameters of the offshore crane system obtained are input into the nonlinear disturbance observer to obtain an aggregate disturbance observation value output by the nonlinear disturbance observer; wherein the aggregate disturbance observation value represents the estimated unmodeled dynamics, parameter perturbation and unknown disturbance of the offshore crane system;

[0010] The mechanical energy, state error vector and swing elimination parameter of the offshore crane system are determined based on the system parameters;

[0011] The mechanical energy, the state error vector and the swing elimination parameter are processed using the storage function to obtain a virtual energy;

[0012] The aggregate disturbance observation value, the mechanical energy, the state error vector and the swing elimination parameter are input into the nonlinear anti-swing controller to obtain a control parameter corresponding to the virtual energy output by the nonlinear anti-swing controller, so that the offshore crane system executes the control parameter.

[0013] Optionally, the system parameters of the offshore crane system obtained are input into the nonlinear disturbance observer to obtain the aggregate disturbance observation value output by the nonlinear disturbance observer, specifically comprising:

[0014] The inertia matrix, Coriolis force matrix, generalized velocity, gravity matrix, and adjustable observation gain matrix are obtained from the system parameters of the offshore crane system.

[0015] Auxiliary variables are determined based on the inertia matrix, the Coriolis force matrix, the generalized velocity, the gravity matrix, and the adjustable observation gain matrix;

[0016] Based on the auxiliary variables, the adjustable observation gain matrix, and the generalized velocity, the aggregated perturbation observations are determined.

[0017] Optionally, the formula for calculating the aggregated perturbation observations is:

[0018] ;

[0019] in, Let k represent the aggregated perturbation observation value, and k represent the adjustable observation gain matrix. This represents the generalized velocity. This refers to the auxiliary variable.

[0020] Optionally, the adjustable observation gain matrix is ​​a diagonal matrix, and the adjustable observation gain matrix is ​​specifically as follows:

[0021] .

[0022] Optionally, determining the mechanical energy, state error vector, and anti-sway parameters of the offshore crane system based on the system parameters specifically includes:

[0023] Obtain from the system parameters the generalized coordinate vector, the expected value of the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term;

[0024] The mechanical energy of the offshore crane system is determined based on the generalized coordinate vector and the generalized velocity.

[0025] Based on the generalized coordinate vector and the expected value of the generalized coordinate vector, the state error vector of the offshore crane system is determined;

[0026] Based on the state error vector, the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term, the anti-sway parameters of the offshore crane system are determined.

[0027] Optionally, determining the state error vector of the offshore crane system based on the generalized coordinate vector and its expected value specifically includes:

[0028] Obtain the first generalized coordinate value, the second generalized coordinate value, and the third generalized coordinate value from the generalized coordinate vector;

[0029] Obtain the first generalized coordinate expectation value, the second generalized coordinate expectation value, and the third generalized coordinate expectation value from the expected value of the generalized coordinate vector;

[0030] The difference between the first generalized coordinate value and the expected value of the first generalized coordinate is determined as the first state error value;

[0031] The difference between the second generalized coordinate value and the expected value of the second generalized coordinate is determined as the second state error value;

[0032] The difference between the third generalized coordinate value and the expected value of the third generalized coordinate is determined as the third state error value;

[0033] The state error vector of the offshore crane system is generated based on the first state error value, the second state error value, and the third state error value.

[0034] Optionally, determining the anti-sway parameters of the offshore crane system based on the state error vector, the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term specifically includes:

[0035] Obtain the fourth and fifth generalized coordinate values ​​from the generalized coordinate vector;

[0036] Based on the first state error value, the first adjustable positive definite gain, the fourth generalized coordinate value, and the first time-varying term, the first anti-sway term is determined;

[0037] Based on the second state error value, the second adjustable positive definite gain, the fifth generalized coordinate value, and the second time-varying term, the second anti-sway term is determined;

[0038] The anti-sway parameters of the offshore crane system are generated based on the first anti-sway term and the second anti-sway term.

[0039] Optionally, the formula for calculating the virtual energy is:

[0040] ;

[0041] in, This refers to the virtual energy. Let e ​​represent the mechanical energy, e represent the state error vector, and H represent the anti-slip parameter.

[0042] A second aspect of the present invention provides an anti-sway nonlinear control system based on a variable frequency drive, comprising: a processor and a memory;

[0043] The memory stores programs or instructions that can run on the processor, which, when executed by the processor, implement the steps of the anti-sway nonlinear control method based on the variable frequency drive as described in the first aspect.

[0044] A third aspect of the present invention provides a readable storage medium on which a program or instructions are stored, which, when executed by a processor, implement the steps of the anti-sway nonlinear control method based on a frequency converter driver as described in the first aspect.

[0045] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0046] In this embodiment of the invention, the nonlinear disturbance observer accurately predicts the unmodeled dynamics of the system and complex external disturbances, and actively counteracts their effects using a feedforward compensation mechanism, significantly enhancing the system's anti-interference capability in the variable marine environment. Simultaneously, an energy storage function is constructed based on energy shaping theory, unifying the positioning error and swing angle information into virtual energy. This energy is dynamically dissipated through a nonlinear controller, achieving inherent coordination and weight optimization between positioning control and swing suppression control. This fundamentally ensures high-precision positioning of the load and effectively suppresses swaying, resulting in robust overall control performance and rapid response. Attached Figure Description

[0047] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0048] Figure 1 This is a flowchart illustrating an anti-sway nonlinear control method based on a variable frequency drive provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of a nonlinear control system for preventing swaying based on a frequency converter driver, provided in an embodiment of the present invention. Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0051] The anti-sway nonlinear control method based on a variable frequency drive provided by the present invention will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0052] Reference manual attached Figure 1 The diagram shows a flowchart of an anti-sway nonlinear control method based on a variable frequency drive provided by an embodiment of the present invention.

[0053] This invention provides an anti-sway nonlinear control method based on a variable frequency drive, which may include the following steps:

[0054] S1: Input the acquired system parameters of the offshore crane system into the nonlinear disturbance observer to obtain the aggregated disturbance observation value output by the nonlinear disturbance observer.

[0055] In this embodiment of the application, the aggregated disturbance observations represent the estimated unmodeled dynamics, parameter perturbations, and unknown disturbances of the offshore crane system.

[0056] In this embodiment of the application, system parameters may include the mast and payload mass. mast length Mast inertia I, effective load lifting / lowering force The length of the rope l(t), the pitch and rotation angles of the mast Radial and tangential oscillation angles of the load And gravitational acceleration g.

[0057] The general formula for the dynamic model of marine engineering equipment is:

[0058] (1)

[0059] in, , and These are the nominal mass matrix, Coriolis force matrix, and gravity matrix of the system, respectively. However, in reality, marine engineering equipment systems are extremely complex. On the one hand, there are some uncertain dynamics that are not considered during operation (common examples include friction models); on the other hand, they are affected by perturbations of internal system parameters and external disturbances (such as inconsistencies between nominal and actual system parameters, wind disturbances, etc.). These factors cause deviations between the theoretical model and reality of marine engineering equipment. Therefore, it is advisable to let... and Let the unknown unmodeled dynamics and external disturbances be represented respectively. These unmodeled dynamics include uncertain frictional forces. Then the system model (1) is:

[0060] (2)

[0061] Regarding the perturbation of internal parameters, let's assume , and For the actual system , and The true value of is then known from (2) as follows:

[0062] (3)

[0063] definition , and Let be the uncertain deviations between the nominal value and the corresponding actual value, then: (4) (5) (6)

[0064] Define aggregate perturbation for:

[0065] (7)

[0066] Combining equations (4) to (7), equation (3) can be written as:

[0067] (8)

[0068] Analysis of Equation (8) shows that unmodeled dynamics, parameter perturbations, and external disturbances can be regarded as aggregated disturbances to U. Therefore, theoretically if If it can be predicted in advance, the matching disturbance in the aggregation disturbance can be handled by using feedforward compensation.

[0069] First, define For aggregation perturbation The observed values ​​are defined. For the observation error, and taking its derivative, we get:

[0070] (9)

[0071] Due to the first derivative of the disturbance Without prior knowledge, and based on Assumption 1, we know it is bounded. For the least loss of generality, we might assume it to be 0. When the observed dynamics are faster than the perturbation dynamics, then... Therefore:

[0072] (10)

[0073] Combining the dynamic model of marine engineering equipment (4) and equation (6), a nonlinear disturbance observer is designed:

[0074] (11)

[0075] In the formula, L is a human-given positive definite observation gain.

[0076] The designed observer (7) is analyzed, and this observer needs to be based on the system state acceleration value. As input, but in practice, acceleration values ​​are difficult to measure directly, and obtaining them directly using a differentiator will indirectly introduce a large amount of noise. Therefore, the observer (7) is further improved. First, auxiliary variables are defined. and for: (12) (13)

[0077] Differentiating equation (9) and substituting equations (7) and (8) into the equation, we get:

[0078] (14)

[0079] Here, let the observation gain L satisfy:

[0080] (15)

[0081] As an optional implementation, S1 inputs the acquired system parameters of the offshore crane system to the nonlinear disturbance observer, and the method for obtaining the aggregated disturbance observation value output by the nonlinear disturbance observer may include:

[0082] The inertia matrix, Coriolis force matrix, generalized velocity, gravity matrix, and adjustable observation gain matrix are obtained from the system parameters of the offshore crane system.

[0083] Auxiliary variables are determined based on the inertia matrix, the Coriolis force matrix, the generalized velocity, the gravity matrix, and the adjustable observation gain matrix;

[0084] Based on the auxiliary variables, the adjustable observation gain matrix, and the generalized velocity, the aggregated perturbation observations are determined.

[0085] This implementation method, by introducing auxiliary variables to construct an improved observer, cleverly avoids the problem of directly measuring system acceleration in traditional designs, effectively overcoming the engineering bottlenecks of difficulty in obtaining acceleration signals and the ease with which noise is introduced. This design significantly improves the estimation accuracy and reliability of aggregated disturbance observations, providing more precise disturbance information for feedforward compensation control, thereby further enhancing the overall performance of the system in suppressing sway and achieving accurate positioning under complex sea conditions.

[0086] In this embodiment of the application, the modified formula for calculating the aggregated perturbation observation is as follows:

[0087] (16)

[0088] in, Let k represent the aggregated perturbation observation value, and k represent the adjustable observation gain matrix. This represents the generalized velocity. This refers to the auxiliary variable.

[0089] The adjustable observation gain matrix is ​​a diagonal matrix, and specifically, the adjustable observation gain matrix is ​​as follows: ,in, All of them have adjustable observation gain.

[0090] as well as,

[0091] (17)

[0092] Comparing equations (7), (12), and (13), it can be seen that the improved observer does not require system state acceleration feedback. Next, a convergence analysis of the observer will be performed.

[0093] S2: Determine the mechanical energy, state error vector, and anti-sway parameters of the offshore crane system based on the system parameters.

[0094] First, we analyze the energy of marine engineering equipment. For the marine engineering equipment represented by equation (4), its mechanical energy... for:

[0095] (18)

[0096] In the formula, the first term represents the kinetic energy of the system, and the second term represents the potential energy of the system. Given that M(q) is a positive definite inertia matrix, then... Positive semi-definite, differentiating both sides of equation (18) yields:

[0097] (19)

[0098] Combining Theorem 1 and rearranging equation (4), we get equation (18):

[0099] (20)

[0100] In the formula,

[0101] (twenty one)

[0102] From equation (20), it can be seen that, with , and The marine engineering equipment system with separate input, output, and energy storage functions is a passive system; therefore, the system can attenuate energy through mast pitch, rotation, and load lifting. It is worth noting that attenuation is achieved through… The energy stored in the marine engineering equipment can only stabilize the equipment, but not bring it to the desired position. Therefore, the positioning error information must be considered when designing the energy storage function. In other words, the positioning error should be treated as part of the system energy, and the desired control task can be achieved by dissipating the energy to zero through the principle of energy dissipation.

[0103] As an optional implementation, S2 may determine the mechanical energy, state error vector, and anti-sway parameters of the offshore crane system based on the system parameters in the following ways:

[0104] Obtain from the system parameters the generalized coordinate vector, the expected value of the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term;

[0105] The mechanical energy of the offshore crane system is determined based on the generalized coordinate vector and the generalized velocity.

[0106] Based on the generalized coordinate vector and the expected value of the generalized coordinate vector, the state error vector of the offshore crane system is determined;

[0107] Based on the state error vector, the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term, the anti-sway parameters of the offshore crane system are determined.

[0108] This implementation method, by systematically integrating mechanical energy, state error, and adjustable anti-sway parameters, constructs a comprehensive energy framework characterizing the system's dynamics. The introduction of a time-varying term and positive definite gain allows for dynamic adjustment of the anti-sway effect's intensity, achieving intelligent trade-offs and synergistic optimization between the two control objectives of positioning and anti-sway. This not only effectively suppresses load oscillations but also ensures the speed and accuracy of the positioning process.

[0109] As an optional implementation, the method for determining the state error vector of the offshore crane system based on the generalized coordinate vector and the expected value of the generalized coordinate vector may include:

[0110] Obtain the first generalized coordinate value, the second generalized coordinate value, and the third generalized coordinate value from the generalized coordinate vector;

[0111] Obtain the first generalized coordinate expectation value, the second generalized coordinate expectation value, and the third generalized coordinate expectation value from the expected value of the generalized coordinate vector;

[0112] The difference between the first generalized coordinate value and the expected value of the first generalized coordinate is determined as the first state error value;

[0113] The difference between the second generalized coordinate value and the expected value of the second generalized coordinate is determined as the second state error value;

[0114] The difference between the third generalized coordinate value and the expected value of the third generalized coordinate is determined as the third state error value;

[0115] The state error vector of the offshore crane system is generated based on the first state error value, the second state error value, and the third state error value.

[0116] This implementation method, by accurately calculating the positioning errors in each degree of freedom, constructs a clear and definite state error vector. This provides the controller with precise positioning deviation information, enabling it to generate targeted control commands to eliminate errors. This directly and effectively improves the system's positioning accuracy, laying a solid foundation for achieving high-precision load delivery.

[0117] In this embodiment of the application, the state error vector is:

[0118] (twenty two)

[0119] In the formula, (twenty three) (twenty four) (25)

[0120] in, , , They are respectively , , The expected value.

[0121] As an optional implementation, the method for determining the anti-sway parameters of the offshore crane system based on the state error vector, the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term may include:

[0122] Obtain the fourth and fifth generalized coordinate values ​​from the generalized coordinate vector;

[0123] Based on the first state error value, the first adjustable positive definite gain, the fourth generalized coordinate value, and the first time-varying term, the first anti-sway term is determined;

[0124] Based on the second state error value, the second adjustable positive definite gain, the fifth generalized coordinate value, and the second time-varying term, the second anti-sway term is determined;

[0125] The anti-sway parameters of the offshore crane system are generated based on the first anti-sway term and the second anti-sway term.

[0126] This implementation method achieves precise and refined anti-sway control by constructing an independent anti-sway term associated with positioning error and sway angle. The introduction of a time-varying term and positive definite gain allows the anti-sway force to be dynamically adjusted according to the system state, thereby effectively suppressing radial and tangential sway while avoiding conflicts with the positioning control target, significantly improving the overall anti-sway performance.

[0127] In this embodiment of the application, the anti-oscillation parameter can specifically be:

[0128] (26)

[0129] in, , All are adjustable positive definite gain; , This is a time-varying term, designed to improve oscillation suppression performance. Its specific function definition is: (27) (28)

[0130] S3: Use the energy storage function to process the mechanical energy, the state error vector, and the anti-slip parameter to obtain virtual energy.

[0131] In this embodiment of the application, the formula for calculating virtual energy is:

[0132] (29)

[0133] in, This refers to the virtual energy. Let e ​​represent the mechanical energy, e represent the state error vector, and H represent the anti-slip parameter. A ∈ R³×3 and A = diag{ , , }, B∈R2×2 and B=diag{ , }

[0134] The first term in equation (29) is the stabilization term. As can be seen from the previous analysis, the function of this term is to facilitate the dissipation of the inherent mechanical energy of the system, thereby stabilizing the system.

[0135] The second term is the positioning error term. Its function is to convert the mast positioning error information into virtual energy of the system. Dissipating this virtual energy can enable the mast in the engineering equipment system to achieve positioning. In theory, the control system can be stabilized to the desired equilibrium point by dissipating the energy of the stabilization term and the positioning error term alone.

[0136] However, due to the underactuated nature of the system, relying solely on the energy dissipation of the first two terms without considering the weighting ratio between anti-sway and positioning performance leaves significant room for improvement in the anti-sway performance of the control system. Therefore, this paper specifically designs a third term, the anti-sway term. This term introduces sway angle information as virtual energy, and the weighting of positioning error and sway angle conversion virtual energy in the total energy can be adjusted by parameters. Thus, dissipating this energy can be achieved by manually setting parameters to regulate the positioning and anti-sway effects.

[0137] S4: Input the aggregated disturbance observation, the mechanical energy, the state error vector, and the anti-sway parameter into the nonlinear anti-sway controller to obtain the control parameters output by the nonlinear anti-sway controller corresponding to the virtual energy, so that the offshore crane system executes the control parameters.

[0138] In this embodiment of the application, it is easy to know the newly constructed energy storage function from equation (25). ,and To dissipate the virtual energy of the designed energy storage function, this paper carefully designs a nonlinear anti-sway controller as follows:

[0139] (30) (31) (32)

[0140] In the formula, , , , , , , , All are adjustable positive definite gains. A rigorous stability analysis of the designed controller will follow.

[0141] In practical applications, the boom luffing motion and the cable lifting motion are mostly controlled independently. This lack of coordination often reduces cargo conveying efficiency and transient control performance. Furthermore, the actuator saturation problem, common in practical applications, is not adequately considered. To address this issue, a bounded coordinate controller is developed.

[0142] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0143] In this embodiment of the invention, the nonlinear disturbance observer accurately predicts the unmodeled dynamics of the system and complex external disturbances, and actively counteracts their effects using a feedforward compensation mechanism, significantly enhancing the system's anti-interference capability in the variable marine environment. Simultaneously, an energy storage function is constructed based on energy shaping theory, unifying the positioning error and swing angle information into virtual energy. This energy is dynamically dissipated through a nonlinear controller, achieving inherent coordination and weight optimization between positioning control and swing suppression control. This fundamentally ensures high-precision positioning of the load and effectively suppresses swaying, resulting in robust overall control performance and rapid response.

[0144] Strong robustness: By predicting and compensating aggregated disturbances in real time, this method has excellent adaptability to unmodeled dynamic and non-stationary disturbances (such as random waves and abrupt ocean currents), which is superior to traditional feedback linearization and sliding mode control.

[0145] Avoid actuator saturation: Nonlinear saturation functions effectively suppress excessive control output and ensure safe operation of the actuator under strong disturbances.

[0146] Global stability: The closed-loop system is rigorously proven to be globally asymptotically stable using Lyapunov theory and the LaSalle invariance principle, demonstrating high theoretical reliability.

[0147] Low energy consumption: Compared with existing methods, this method requires less control input and consumes less energy.

[0148] Reference manual attached Figure 2 The diagram shows a schematic of the anti-sway nonlinear control system based on a variable frequency drive provided by an embodiment of the present invention.

[0149] This invention provides an anti-sway nonlinear control system 20 based on a variable frequency drive, comprising: a processor 201 and a memory 202;

[0150] The memory 202 stores programs or instructions that can run on the processor 201. When the program or instructions are executed by the processor 201, they implement the steps of the above-described anti-sway nonlinear control method based on the variable frequency drive and achieve the same technical effect. To avoid repetition, the present invention will not elaborate further.

[0151] It should be understood that the processor 201 in this embodiment of the invention may be a central processing unit (CPU), or it may be 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, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0152] It should also be understood that the memory 202 in the embodiments of the present invention can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct memory bus RAM (DR RAM).

[0153] The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0154] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0155] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0156] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0157] In the several embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0158] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0159] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0160] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0161] This invention provides a readable storage medium comprising: storing a program or instructions on the readable storage medium, wherein when the program or instructions are executed by a processor, the program or instructions implement the steps of the above-described anti-sway nonlinear control method based on a frequency converter driver, and can achieve the same technical effect. To avoid repetition, this invention will not elaborate further.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A nonlinear control method for preventing swaying based on a variable frequency drive, characterized in that, include: The acquired system parameters of the offshore crane system are input into a nonlinear disturbance observer to obtain the aggregated disturbance observation value output by the nonlinear disturbance observer; wherein, the aggregated disturbance observation value represents the estimated unmodeled dynamics, parameter perturbations, and unknown disturbances of the offshore crane system; Based on the system parameters, determine the mechanical energy, state error vector, and anti-sway parameters of the offshore crane system; The mechanical energy, the state error vector, and the anti-slip parameters are processed using an energy storage function to obtain virtual energy; The aggregated disturbance observation, the mechanical energy, the state error vector, and the anti-sway parameters are input into the nonlinear anti-sway controller to obtain the control parameters output by the nonlinear anti-sway controller corresponding to the virtual energy, so that the offshore crane system executes the control parameters.

2. The anti-sway nonlinear control method based on a variable frequency drive according to claim 1, characterized in that, The process of inputting the acquired system parameters of the offshore crane system into a nonlinear disturbance observer to obtain the aggregated disturbance observation value output by the nonlinear disturbance observer specifically includes: The inertia matrix, Coriolis force matrix, generalized velocity, gravity matrix, and adjustable observation gain matrix are obtained from the system parameters of the offshore crane system. Auxiliary variables are determined based on the inertia matrix, the Coriolis force matrix, the generalized velocity, the gravity matrix, and the adjustable observation gain matrix; Based on the auxiliary variables, the adjustable observation gain matrix, and the generalized velocity, the aggregated perturbation observations are determined.

3. The anti-sway nonlinear control method based on a variable frequency drive according to claim 2, characterized in that, The formula for calculating the aggregated perturbation observation is as follows: ； in, Let k represent the aggregated perturbation observation value, and k represent the adjustable observation gain matrix. This represents the generalized velocity. This refers to the auxiliary variable.

4. The anti-sway nonlinear control method based on a variable frequency drive according to claim 3, characterized in that, The adjustable observation gain matrix is ​​a diagonal matrix, and specifically, the adjustable observation gain matrix is ​​as follows: 。 5. The anti-sway nonlinear control method based on a variable frequency drive according to claim 2, characterized in that, The determination of the mechanical energy, state error vector, and anti-sway parameters of the offshore crane system based on the system parameters specifically includes: Obtain from the system parameters the generalized coordinate vector, the expected value of the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term; The mechanical energy of the offshore crane system is determined based on the generalized coordinate vector and the generalized velocity. Based on the generalized coordinate vector and the expected value of the generalized coordinate vector, the state error vector of the offshore crane system is determined; Based on the state error vector, the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term, the anti-sway parameters of the offshore crane system are determined.

6. The anti-sway nonlinear control method based on a variable frequency drive according to claim 5, characterized in that, Determining the state error vector of the offshore crane system based on the generalized coordinate vector and its expected value specifically includes: Obtain the first generalized coordinate value, the second generalized coordinate value, and the third generalized coordinate value from the generalized coordinate vector; Obtain the first generalized coordinate expectation value, the second generalized coordinate expectation value, and the third generalized coordinate expectation value from the expected value of the generalized coordinate vector; The difference between the first generalized coordinate value and the expected value of the first generalized coordinate is determined as the first state error value; The difference between the second generalized coordinate value and the expected value of the second generalized coordinate is determined as the second state error value; The difference between the third generalized coordinate value and the expected value of the third generalized coordinate is determined as the third state error value; The state error vector of the offshore crane system is generated based on the first state error value, the second state error value, and the third state error value.

7. The anti-sway nonlinear control method based on a variable frequency drive according to claim 6, characterized in that, The determination of the anti-sway parameters of the offshore crane system based on the state error vector, the generalized coordinate vector, the first adjustable positive definite gain, the second adjustable positive definite gain, the first time-varying term, and the second time-varying term specifically includes: Obtain the fourth and fifth generalized coordinate values ​​from the generalized coordinate vector; Based on the first state error value, the first adjustable positive definite gain, the fourth generalized coordinate value, and the first time-varying term, the first anti-sway term is determined; Based on the second state error value, the second adjustable positive definite gain, the fifth generalized coordinate value, and the second time-varying term, the second anti-sway term is determined; The anti-sway parameters of the offshore crane system are generated based on the first anti-sway term and the second anti-sway term.

8. The anti-sway nonlinear control method based on a variable frequency drive according to claim 7, characterized in that, The formula for calculating the virtual energy is: ； in, This refers to the virtual energy. Let e ​​represent the mechanical energy, e represent the state error vector, and H represent the anti-slip parameter.

9. A nonlinear control system for preventing swaying based on a variable frequency drive, characterized in that, include: Processor and memory; The memory stores programs or instructions that can run on the processor, which, when executed by the processor, implement the steps of the anti-sway nonlinear control method based on a frequency converter driver as described in any one of claims 1 to 8.

10. A readable storage medium, characterized in that, The readable storage medium stores a program or instructions that, when executed by a processor, implement the steps of the anti-sway nonlinear control method based on a frequency converter driver as described in any one of claims 1 to 8.

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