NTSMC-based offshore lightering device tail end horizontal stability maintenance control method

Abstract

The invention discloses a marine lightering device tail end horizontal stability maintenance control method based on NTSMC, and the method comprises the following steps: S1, building a horizontal luffing mechanism kinematic model based on kinematic analysis; s2, establishing a function relationship between the amplitude variation angle and the stroke of the driving device by using the mathematical model of the driving device and the kinematic model of the amplitude variation mechanism; s3, establishing a driving device mathematical model; s4, deducing an NTSMC control law by using the driving device mathematical model; and S5, establishing a system control model in combination with the NTSMC control law and the luffing mechanism transmission relationship. The method has relatively good control robustness and control precision, can realize efficient and safe lightering operation of personnel and materials, and is suitable for equipment for personnel and material maritime lightering such as a maritime wind turbine embarkation device; according to the invention, the safety and efficiency of the lightering operation of offshore personnel and materials can be obviously improved.

Description

TECHNICAL FIELD

[0001] The application provides a complex amplitude mechanism optimization design method based on a multi-objective particle swarm algorithm, and belongs to the technical field of mechanical engineering. BACKGROUND

[0002] With the deepening of the development and utilization of marine resources, offshore transportation, personnel transfer and material supply operations are becoming more and more frequent. The trestle connecting the ship and the offshore facility (such as a wind turbine or a drilling platform) is a key offshore connection channel, and its operation safety and stability are crucial. However, the wave motion in the marine environment causes the operating ship to oscillate in six degrees of freedom, and this motion is transmitted to the landing point at the end of the trestle through the trestle, causing the end platform to move violently, which will greatly threaten the safe transfer of personnel and materials, and also severely limit the operation window of the trestle in severe sea conditions.

[0003] The core of the wave compensation system is its actuator and control strategy. Among various actuators, servo cylinders are gradually replacing traditional hydraulic drive systems as the ideal choice for high-precision wave compensation system actuators due to their high precision, high response speed, cleanliness, ease of maintenance, and other significant advantages. However, the permanent magnet synchronous motor, the core component of the servo cylinder, is a strongly coupled and complex nonlinear system that is not easy to achieve high control accuracy. Its main defects include model uncertainty, external disturbance and measurement noise. Traditional PID control often struggles to balance dynamic response speed and steady-state accuracy when dealing with such complex nonlinear systems, and its robustness is poor. In order to improve control performance, a control algorithm with strong robustness to parameter perturbation and external disturbance and high control accuracy is needed to ensure the safety of boarding operations. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a NTSMC-based offshore transfer device end horizontal stabilization control method that maintains the offshore transfer device end horizontal to the ground in high sea conditions, and the method has good control robustness and control accuracy, can realize efficient and safe personnel and material transfer operations, and is suitable for offshore wind turbine boarding devices and other equipment used for personnel and material offshore transfer. The present application can significantly improve the safety and efficiency of offshore personnel and material transfer operations.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: A NTSMC-based offshore transfer device end horizontal stabilization control method, comprising the following steps: S1. Based on kinematic analysis, establish a kinematic model of the horizontal luffing mechanism; S2. Using the mathematical model of the drive device and the kinematic model of the luffing mechanism, establish a functional relationship between the luffing angle and the stroke of the drive device; S3. Establish a mathematical model of the drive device; S4. Use the mathematical model of the drive device to derive the NTSMC control law; S5. Combine the NTSMC control law and the transmission relationship of the luffing mechanism to establish a system control model.

[0006] Furthermore, in step S1, kinematic analysis is performed on the six-hinged luffing mechanism driven by an electric servo. When the actuator moves, the luffing arm rotates around point O. θ Angle, at this time points B, C, E, and F move to points B', C', E', and F' respectively, and establish the kinematic model of the variable amplitude mechanism: (1) in, (2) Points B, C, and D are three points on the luffing boom; points A and B are two points on the fixed boom; point B is the rotation center of the luffing boom; points A, E, and F are three hinge points on link 1; points E and C are two hinge points on link 2; points E and F are connected by an electric cylinder; and the coordinates of points A, C, E, and F are respectively (…). a 1, a 2), ( c 1, c 2), ( e 1, e 2), ( f 1, f 2) L1 is the length of AE, and L2 is the length of EC. L This refers to the length of the electric cylinder.

[0007] Furthermore, in step S2, a functional relationship is established between the amplitude change angle and the stroke of the drive device. The amplitude change motion is achieved by rotating the electric cylinder motor. From the motion relationship between the servo motor and the ball screw, the linear displacement equation of the servo cylinder is obtained as follows: (3) In the formula: L 0 represents the shortest installation distance for the servo electric cylinder. P b For the lead screw, Combining equations (2) and (3), the functional relationship between the servo electric cylinder motor rotation angle and the drive device stroke can be obtained as follows: (4).

[0008] Furthermore, in step S3, a mathematical model of the drive device is established, using an electric servo cylinder as the drive system. The servo motor has three control modes: torque mode, speed mode, and position mode. First, to facilitate mathematical modeling of the servo motor, a simplified analysis and simplified assumptions are made. Then, based on these assumptions, the servo motor's performance in various functions is obtained through mathematical analysis and derivation of the model. d q Mathematical models in rotating coordinate systems include: The stator voltage equation is: (5) In the formula: u d and u q for d shaft and q Stator voltage V of the shaft; i d and i q for d shaft and q The stator current A of the shaft, The rotor angular velocity is rad / s; L d and Lq They are respectively d and q The inductance H of the shaft, Assign values ​​to the rotor flux linkage. The electromagnetic torque equation is: (6) In the formula: P is the pole logarithm. The equation of motion for the machine is: (7) In the formula: l Rotor moment of inertia (kg·m) 2 ; ω m The mechanical angular velocity of the motor is rad / s; T i The equivalent load torque of the motor shaft is N·m; B The damping coefficient is N·m·s / rad. To achieve the maximum torque-to-current ratio of the servo motor, the following is adopted: i d =0 control method, the mathematical model of servo motor described by equations (5), (6), and (7) is simplified as follows: (8) In the formula, K e The back electromotive force coefficient,K e = P n Ψ f , K T The torque coefficient, K T =1.5 P n Ψ f , P n This represents the number of pole pairs of the motor. Ψ f Assign values ​​to the rotor flux linkage. When using position control mode to control the servo electric cylinder, the default equivalent load torque of the servo motor shaft is zero. Therefore, the mechanical angular displacement of the servo motor is derived. q The differential function relationship of the shaft voltage is: (9) (10).

[0009] Furthermore, a simplified analysis of the servo motor is conducted and simplified assumptions are made, including: (1) there is an electrical angle difference between the stator windings of the three-phase motor, which leads to the induction of a sinusoidal electromotive force by the air gap magnetic field; (2) the effect of the motor rotor damping winding is not considered; (3) the effect of eddy current and hysteresis loss on motor performance is ignored; (4) the self-inductance and mutual inductance of the motor windings are assumed to remain unchanged, and the magnetic circuit saturation effect is not included in the consideration of motor performance; (5) the permanent magnet is assumed to have no conductivity and its permeability is approximately the same as that of air; (6) when evaluating motor performance, factors that may affect performance, such as frequency and temperature, are not taken into consideration.

[0010] Furthermore, in step S4, the NTSMC control law is derived. Based on the equivalent control strategy, the sliding mode control quantity is determined by the equivalent control law. u eq and switching control rate u sw The equivalent control law enables the subsystem state variables to slide towards the equilibrium point on a specific sliding surface, while the switching control law enables the system state to move toward this specific sliding surface. Therefore, the sliding control law is established by the following formula. (11) Because there is a geometric relationship between the servo motor rotation angle and the luffing mechanism's luffing angle, the control of the luffing mechanism is converted into the control of the servo motor rotation angle. In order to achieve this within a limited time... t f The servo motor is rotated to the desired angle, and the control target is set as follows: (12) A sliding surface is defined as a terminal sliding surface as follows. (13) in, c >0, at the same time p and q All are positive odd numbers and satisfy 1 < p / q <2. Compared to linear sliding surfaces, the terminal sliding surface defined by equation (13) introduces nonlinear terms, which causes the system to converge in a finite amount of time.

[0011] when When combined with equation (9), the equivalent control law is derived as follows: (14) To ensure that the system state trajectory reaches the sliding surface, the control law is switched as follows: (15).

[0012] Furthermore, to address the singularity problem that arises when using equation (15) due to the exponential term in the denominator approaching zero, resulting in the switching control law output approaching infinity, equation (15) is rewritten as a non-singular switching control law as shown below. (16) Finally, substituting equations (14) and (16) into equation (11), we can obtain the NTSMC control quantity as follows: (17) To reduce chattering, the saturation function sat(), as shown in the following equation, is used instead of the sign function. (18) Where Δ is a constant representing the boundary layer thickness of the saturation function.

[0013] Furthermore, in step S5, a system control model is established by combining the NTSMC control law and the transmission relationship of the luffing mechanism. Based on the results derived in steps S1 to S4, a system control model is established.

[0014] The beneficial effects of this invention are: 1) A horizontal stability control method for the terminal of a marine transshipment device based on NTSMC is proposed, which can significantly improve the operational efficiency of the transshipment device.

[0015] 2) The NTSMC control algorithm is adopted. This algorithm has high robustness and can adapt to large changes in system parameters. The control output is not prone to divergence, thereby improving the safety of operation. Attached Figure Description

[0016] Figure 1 A flowchart for the optimization design of a complex variable amplitude mechanism based on a multi-objective particle swarm optimization algorithm; Figure 2 A simplified diagram of a six-hinged amplitude transformer mechanism; Figure 3 This is a control block diagram. Detailed Implementation

[0017] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] like Figure 1 As shown, the present invention provides a horizontal stability control method for the end of a marine transshipment device based on NTSMC. First, the kinematic model of the mechanism is derived based on the luffing mechanism structure of the transshipment device. On this basis, a functional relationship between the luffing angle and the stroke of the drive device is established. At the same time, a mathematical model of the drive device is established, and on this basis, the NTSMC control law based on the drive device model is derived. Finally, the system control model is established by combining the control law and the functional relationship.

[0019] The embodiments of the present invention include the following steps: S1, as Figure 2 As shown, a kinematic analysis is performed using a six-hinged luffing mechanism driven by an electric servo as an example. In the figure, points B, C, and D are three points on the luffing arm, points A and B are two points on the fixed arm, and point B is the rotation center of the luffing arm. Points A, E, and F are three hinge points on link 1, and points E and C are two hinge points on link 2. Points E and F are connected by an electric cylinder. The coincident points on different booms and links in the figure are the hinge points. The coordinates of points A, C, E, and F are respectively (…). a 1, a 2), ( c 1, c 2), ( e 1, e 2), ( f 1, f 2) Set the length of AE to L1, the length of EC to L2, and the length of the electric cylinder to be... L When the actuator moves, the boom rotates around point O. θ Angle, at this time points B, C, E, and F move to points B', C', E', and F' respectively, and establish the kinematic model of the variable amplitude mechanism: (1) in, (2) S2, establish the functional relationship between the amplitude change angle and the stroke of the drive device. In this example, the amplitude change motion is achieved by driving the electric cylinder motor to rotate.

[0020] The kinematic relationship between the servo motor and the ball screw indicates that the linear displacement equation of the servo electric cylinder is: (3) In the formula: L 0 represents the shortest installation distance for the servo electric cylinder. P b This refers to the lead of the lead screw.

[0021] Combining equations (2) and (3), the functional relationship between the servo electric cylinder motor rotation angle and the drive device stroke can be obtained as follows: (4) S3. Establish a mathematical model of the drive device. In this example, an electric servo cylinder is used as the drive system. The servo motor is the main component of the servo electric cylinder, and it has three control modes: torque mode, speed mode, and position mode. To facilitate mathematical modeling of the servo motor, a simplified analysis is performed, and the following assumptions are made: (1) There is an electrical angle difference between the stator windings of the three-phase motor, which leads to the induced electromotive force of the air gap magnetic field.

[0022] (2) The effect of the motor rotor damping winding is not considered.

[0023] (3) Assume that the effects of eddy current and hysteresis losses on motor performance are negligible.

[0024] (4) Assume that the self-inductance and mutual inductance of the motor winding remain unchanged, and do not take the magnetic circuit saturation effect into consideration for the motor performance.

[0025] (5) Assume that permanent magnets do not have electrical conductivity and their permeability is approximately the same as that of air.

[0026] (6) When evaluating motor performance, factors that may affect performance, such as frequency and temperature, were not taken into consideration.

[0027] Based on the above assumptions, the servo motor can be obtained through mathematical analysis and derivation of the model. d q Mathematical model in a rotating coordinate system.

[0028] The stator voltage equation is: (5) In the formula: u d and u q for d shaft and q Stator voltage (V) of the shaft; i d andi q for d shaft and q Stator current (A) of the shaft; ω is the rotor angular velocity (rad / s); L d and Lq They are respectively d and q The inductance (H) of the shaft.

[0029] The electromagnetic torque equation is: (6) In the formula: P is the pole logarithm.

[0030] The equation of motion for the machine is: (7) In the formula: l Rotor moment of inertia (kg·m) 2 ); ω m The mechanical angular velocity of the motor (rad / s); T i The equivalent load torque of the motor shaft is (N·m). B The damping coefficient is (N·m·s / rad).

[0031] To achieve the maximum torque-to-current ratio for the servo motor, this paper adopts... i d =0 control method, therefore the mathematical model of the servo motor described by equations (5), (6), and (7) can be simplified to: (8) In the formula, K e The back electromotive force coefficient, K e = P n Ψ f , K T The torque coefficient, K T =1.5 P n Ψ f , P n Number of pole pairs of the motor Ψ f Assign a value to the rotor flux linkage.

[0032] When using position control mode to control a servo electric cylinder, the equivalent load torque of the servo motor shaft can be assumed to be zero by default. From this, the mechanical angular displacement of the servo motor can be derived. q The differential function relationship of the shaft voltage is: (9) (10) S4, Deriving the NTSMC control law Based on the equivalent control strategy, the sliding mode control quantity is usually determined by the equivalent control law. u eq and switching control rate u sw The equivalent control law enables the subsystem state variables to slide towards the equilibrium point on a specific sliding surface, while the switching control law enables the system state to move toward this specific sliding surface. Therefore, the sliding control law can be established as follows: (11) Because there is a geometric relationship between the servo motor rotation angle and the luffing mechanism's luffing angle, controlling the luffing mechanism can be converted into controlling the servo motor rotation angle. This allows for control of the luffing mechanism within a limited timeframe. t f To rotate the servo motor to the desired angle, the control target can be set as follows. (12) A sliding surface is defined as a terminal sliding surface as follows. (13) in, c >0, at the same time p and q All are positive odd numbers and satisfy 1 < p / q <2. Compared to linear sliding surfaces, the terminal sliding surface defined by equation (13) introduces a nonlinear term, thus enabling the system to converge in a finite time.

[16] .

[0033] when When combined with equation (9), the equivalent control law is derived as follows: (14) To ensure that the system state trajectory reaches the sliding surface, the control law is typically switched according to the following design. (15) However, when using equation (15), the exponential term in the denominator may cause a singularity problem, i.e., the denominator approaches zero, at which point the switching control law output will approach infinity. To solve this problem, equation (15) can be rewritten as a non-singular switching control law as shown below. (16) Finally, substituting equations (14) and (16) into equation (11), we can obtain the NTSMC control quantity as follows: (17) Furthermore, since the above equation uses a sign function, the system state may chatter near the sliding surface. Therefore, to reduce chattering, the saturation function sat() shown in the following equation can be used instead of the sign function. (18) Where Δ is a constant representing the boundary layer thickness of the saturation function.

[0034] S5, based on the above derivation results, can be established as follows: Figure 3 The system control model shown is shown.

[0035] The above embodiments are only used to illustrate the design concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The scope of protection of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications made based on the principles and design ideas disclosed in the present invention are within the scope of protection of the present invention.

Claims

1. A method for end-of-line horizontal stability control of a marine transshipment device based on NTSMC, characterized in that, Includes the following steps: S1. Based on kinematic analysis, establish a kinematic model of the horizontal luffing mechanism; S2. Using the mathematical model of the drive device and the kinematic model of the luffing mechanism, establish a functional relationship between the luffing angle and the stroke of the drive device; S3. Establish a mathematical model of the drive device; S4. Use the mathematical model of the drive device to derive the NTSMC control law; S5. Combine the NTSMC control law and the transmission relationship of the luffing mechanism to establish a system control model.

2. The method for end-of-line horizontal stability control of a marine transshipment device based on NTSMC according to claim 1, characterized in that, In step S1, kinematic analysis is performed on the six-hinged luffing mechanism driven by an electric servo. When the actuator moves, the luffing arm rotates around point O. θ Angle, at this time points B, C, E, and F move to points B', C', E', and F' respectively, and establish the kinematic model of the variable amplitude mechanism: (1) in, （2） Points B, C, and D are three points on the luffing boom; points A and B are two points on the fixed boom; point B is the rotation center of the luffing boom; points A, E, and F are three hinge points on connecting rod 1; points E and C are two hinge points on connecting rod 2; points E and F are connected by an electric cylinder; and the coordinates of points A, C, E, and F are respectively (…). a 1, a 2), ( c 1, c 2), ( e 1, e 2), ( f 1, f 2) L1 is the length of AE, and L2 is the length of EC. L This refers to the length of the electric cylinder.

3. The method for end-of-line horizontal stability control of a marine transshipment device based on NTSMC according to claim 1, characterized in that, In step S2, a functional relationship is established between the amplitude change angle and the stroke of the drive device. The amplitude change motion is achieved by rotating the electric cylinder motor. From the motion relationship between the servo motor and the ball screw, the linear displacement equation of the servo cylinder is obtained as follows: (3) In the formula: L 0 represents the shortest installation distance for the servo electric cylinder. P b For the lead screw, Combining equations (2) and (3), the functional relationship between the servo electric cylinder motor rotation angle and the drive device stroke can be obtained as follows: (4)。 In step S3, a mathematical model of the drive device is established, using an electric servo cylinder as the drive system. The servo motor has three control modes: torque mode, speed mode, and position mode. First, to facilitate mathematical modeling of the servo motor, a simplified analysis and simplified assumptions are made. Then, based on these assumptions, the servo motor's performance in various modes is obtained through mathematical analysis and derivation of the model. d q Mathematical models in rotating coordinate systems include: The stator voltage equation is: (5) In the formula: u d and u q for d shaft and q Stator voltage V of the shaft; i d and i q for d shaft and q The stator current A of the shaft, The rotor angular velocity is rad / s; L d and Lq They are respectively d and q The inductance H of the shaft, Assign values ​​to the rotor flux linkage. The electromagnetic torque equation is: (6) In the formula: P is the pole logarithm. The equation of motion for the machine is: (7) In the formula: l Rotor moment of inertia (kg·m) 2 ; ω m The mechanical angular velocity of the motor is rad / s; T i The equivalent load torque of the motor shaft is N·m; B The damping coefficient is N·m·s / rad. To achieve the maximum torque-to-current ratio of the servo motor, the following is adopted: i d =0 control method, the mathematical model of servo motor described by equations (5), (6), and (7) is simplified as follows: (8) In the formula, K e The back electromotive force coefficient, K e = P n Ψ f , K T The torque coefficient, K T =1.5 P n Ψ f , P n This represents the number of pole pairs of the motor. Ψ f Assign values ​​to the rotor flux linkage. When using position control mode to control the servo electric cylinder, the default equivalent load torque of the servo motor shaft is zero. Therefore, the mechanical angular displacement of the servo motor is derived. q The differential function relationship of the shaft voltage is: (9) (10)。 4. The method for end-of-line horizontal stability control of a marine transshipment device based on NTSMC according to claim 3, characterized in that, The servo motor is simplified and simplified assumptions are made, including: (1) there is an electrical angle difference between the stator windings of the three-phase motor, which leads to the induced electromotive force of the air gap magnetic field. (2) the effect of the motor rotor damping winding is not considered. (3) the effect of eddy current and hysteresis loss on motor performance is ignored. (4) the self-inductance and mutual inductance of the motor windings are assumed to remain unchanged, and the magnetic circuit saturation effect is not included in the consideration of motor performance. (5) the permanent magnet is assumed to have no conductivity and its permeability is approximately the same as that of air. (6) when evaluating motor performance, factors that may affect performance, such as frequency and temperature, are not taken into consideration.

5. The method for end-of-line horizontal stability control of a marine transshipment device based on NTSMC according to claim 1, characterized in that, In step S4, the NTSMC control law is derived. Based on the equivalent control strategy, the sliding mode control quantity is determined by the equivalent control law. u eq and switching control rate u sw The equivalent control law enables the subsystem state variables to slide towards the equilibrium point on a specific sliding surface, while the switching control law enables the system state to move toward this specific sliding surface. Therefore, the sliding control law is established by the following formula. (11) Because there is a geometric relationship between the servo motor rotation angle and the luffing mechanism's luffing angle, the control of the luffing mechanism is converted into the control of the servo motor rotation angle. In order to achieve this within a limited time... t f The servo motor is rotated to the desired angle, and the control target is set as follows: (12) A sliding surface is defined as a terminal sliding surface as follows. (13) in, c >0, at the same time p and q All are positive odd numbers and satisfy 1 < p / q <2, Compared to linear sliding surfaces, the terminal sliding surface defined by equation (13) introduces nonlinear terms, causing the system to converge in a finite time. when When combined with equation (9), the equivalent control law is derived as follows: (14) To ensure that the system state trajectory reaches the sliding surface, the control law is switched as follows: (15)。 6. The method for end-of-line horizontal stability control of a marine transshipment device based on NTSMC according to claim 5, characterized in that, To address the singularity problem that arises when using equation (15) due to the exponential term in the denominator approaching zero, which causes the switching control law output to approach infinity, equation (15) is rewritten as a non-singular switching control law as shown below. (16) Finally, substituting equations (14) and (16) into equation (11), we can obtain the NTSMC control quantity as follows: (17) To reduce chattering, the saturation function sat(), as shown in the following equation, is used instead of the sign function. (18) Where Δ is a constant representing the boundary layer thickness of the saturation function.

7. The method for end-of-line horizontal stability control of a marine transshipment device based on NTSMC according to claim 1, characterized in that, In step S5, a system control model is established by combining the NTSMC control law and the transmission relationship of the luffing mechanism. Based on the results derived in steps S1 to S4, a system control model is established.

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