Dynamic positioning motion forecast auxiliary pile pitching method for self-elevating ocean platform

Abstract

The invention relates to the technical field of ship motion control, and discloses a dynamic positioning motion forecast auxiliary pile pitching method for a self-elevating ocean platform, and the method comprises the steps: recording the stable drift speed and direction of the platform under a target heading near a target pile pitching position; calculating an initial maneuvering target position according to the drifting information, the water depth and the pile driving speed; after the control platform reaches the initial target position, motion forecasting is carried out, and the position of the platform is longitudinally adjusted, so that the forecasted motion trail passes through the target instrumentation position; and pile descending is conducted under forecast guidance, the platform is decelerated by making pile legs contact the bottom, and when the platform reaches the target pile inserting position, the pile legs enter the mud to fix the position and the heading direction. According to the method, the difficulty that conventional fixed-point pile pitching operation is difficult to carry out under strong ocean current due to the fact that the transverse propelling capacity of the platform is insufficient can be overcome, motion forecasting and longitudinal control are combined, decision guidance is provided for operators, pile pitching operation is assisted to be completed, and the engineering application value is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship motion control, and particularly relates to a dynamic positioning motion prediction auxiliary pile driving method for a self-elevating offshore platform. BACKGROUND

[0002] The main function of a dynamic positioning system of a surface ship or platform is to resist the environmental forces of wind, wave and current by automatic control of the equipped propeller, so as to realize automatic control of three degrees of freedom of position and heading, so that the ship can maintain the set position, heading and trajectory to meet the needs of specific operation tasks.

[0003] When the self-elevating offshore platform is in pile driving operation, the platform propelling capacity may be insufficient to resist the environmental forces of wind, wave and current, especially the transverse propelling capacity. At this time, it is unrealistic to control the platform near the pile driving target point by using the fixed point positioning mode of dynamic positioning. This puts forward the demand for platform pile driving positioning under the condition of insufficient propelling capacity of the dynamic positioning system.

[0004] In view of this demand, a motion prediction technology is proposed, which uses a model-based motion prediction method to calculate the motion state of the platform in a future period of time, and provides an auxiliary decision for the operator to select the pile driving time. This technology effectively solves the pile driving positioning problem under the condition of insufficient propelling capacity which cannot be solved by the conventional dynamic positioning system, and can assist the operator to complete the pile driving positioning and ensure the subsequent sea operation tasks. SUMMARY

[0005] The present application aims to at least solve one of the problems in the related art. To this end, the present application provides a dynamic positioning motion prediction and auxiliary pile driving method for a self-elevating offshore platform.

[0006] A dynamic positioning motion prediction and auxiliary pile driving method for a self-elevating offshore platform, S1: obtaining a target pile driving position, a target pile driving heading, a water depth, a platform draft and a pile driving speed, setting the platform heading to the target pile driving heading when the platform moves to a distance within a first threshold range from the target pile driving position, and collecting the drift speed and drift direction of the platform; S2: obtaining an initial maneuver target position of the platform according to the target pile driving position, the target pile driving heading, the water depth, the platform draft and the pile driving speed; S3: adjusting the platform heading and moving to the initial maneuver target position, and adjusting the platform heading to the target pile driving heading when the platform moves to the initial maneuver target position; S4: establishing a low-frequency motion prediction model of the platform, performing motion prediction based on the low-frequency motion prediction model, and outputting a position prediction sequence in a future period of time; adjusting the longitudinal position of the platform based on the prediction sequence, so that the trajectory of the position prediction sequence passes through the target pile driving position; S5: while keeping the motion prediction continuously output, start the spud leg driving operation, monitor the remaining time to reach the target driving position, the water depth and the spud leg driving length; The remaining time to reach the target driving position is the time required for the berth position to move to the target driving position in the motion prediction; S6: when the platform moves to a distance within a second threshold range from the target driving position, determine whether the spud leg has reached the bottom, and use the friction between the spud leg and the seabed to slow down the platform; S7: when the platform reaches the target driving position, control the spud leg to drive into the mud, keep the platform position and heading, and terminate the dynamic positioning operation.

[0007] Further, S1 includes the following steps: B1: start the fixed-point positioning mode of dynamic positioning at the target driving position within a radius threshold range, and record the coordinates in the geodetic coordinate system as ; B2: set the platform heading to the target driving heading ; B3: after the platform rotates to the target driving heading and the drift speed is stable under the action of environmental forces, record the cross drift speed and the cross drift direction at this time; when the platform drifts to the port side, record ; when the platform drifts to the starboard side, record .

[0008] Further, S2 includes the following steps: C1: obtain the water depth of the target driving position, the platform draft and the driving speed information; calculate the driving time such as formula (1): Formula (1) In the formula, is the driving speed, is the water depth, is the platform draft; C2: the initial maneuver target position in the geodetic coordinate system is recorded as , and is calculated as formula (2): Formula (2) The initial maneuver target position is upstream of the target driving position.

[0009] Further, S3 includes the following steps: D1: in the fixed-point positioning mode, set the target position of the platform as the initial maneuvering target position , and set the target heading of the platform as ; D2: after the platform moves to the target position and the target heading set in D1, set the target heading of the platform as the target mooring heading .

[0010] Further, S4 comprises the following steps: E1: establish a dynamic positioning motion prediction mathematical model, which is a simplified form of the low-frequency dynamics model in the state estimation model as formula (3): Formula (3) In the formula, and are the northward position and eastward position of the platform in the platform geodetic coordinate system, respectively; represents the first derivative of n, i.e., the northward acceleration; represents the first derivative of e, i.e., the eastward acceleration; is the cross-translation velocity; represents the first derivative of , i.e., the cross-translation acceleration; is the mass of the platform, is the cross-translational hydrodynamic acceleration derivative; is the cross-translational hydrodynamic velocity derivative; is the cross-translational thrust generated by the thruster; is the cross-translational wind load; and are the northward and eastward environmental disturbance loads, respectively; the predicted state vector in the model is a 3-dimensional state vector; E2: based on the model in E1, perform motion prediction, output 1 position per second, output a sequence of geodetic coordinate system positions within a prediction time threshold, and use the state estimation value output by the current dynamic positioning control cycle as the prediction initial value; the cross-translational thrust, the cross-translational wind load, and the environmental disturbance load also use the calculation results used by the state estimation; E3: use the hand-operated mode of dynamic positioning for longitudinal motion, adjust the forward and backward position of the platform through the hand-operated lever, and make the predicted position pass through the target mooring position.

[0011] Further, the specific operation of E3 is as follows: E31: calculate the target mooring position , which is the foot point of the straight line on which the predicted position sequence lies , is the coordinate in the geodetic coordinate system , which is obtained by solving the equation group of formula (4); Formula (4) In the formula, is the coordinate of the first point of the predicted position sequence ; is the coordinate of the last point of the predicted position sequence ; E32: Calculate the vector using formula (5) Coordinates in the geodetic coordinate system , Formula (5) The geodetic coordinate system takes the target splicing point as the origin, with x pointing north and y pointing east; E33: Calculate the vector using formula (6) Coordinates in the platform coordinate system , Formula (6) The origin of the platform coordinate system is the center of gravity of the berth, with x pointing towards the bow and y pointing to the right side; E34: Adjust the front and rear positions of the platform according to When , the platform moves forward; when , the platform moves backward.

[0012] Further, S5 includes the following steps: F1: Calculate the remaining time to reach the target splicing position, F2: Continuously monitor the water depth and spud leg lowering length using the water depth sensor and spud leg monitoring system.

[0013] Further, the step of calculating the remaining time to reach the target splicing position includes: F11: Calculate the northward and eastward deviations of the current predicted position in the geodetic coordinate system from the target splicing position, denoted as and respectively; and calculate the northward and eastward deviations of the last predicted position in the geodetic coordinate system from the target splicing position, denoted as and : Formula (7) In the formula, K and K-1 represent the Kth and K-1th times in the predicted sequence respectively; F12: Calculate the lateral deviation of the current predicted position from the target splicing position in the platform coordinate system, denoted as ; and calculate the lateral deviation of the last predicted position from the target splicing position, denoted as : Formula (8); F13: calculating the remaining time to reach the target pile insertion position, If , the output is the predicted remaining time to reach the target pile insertion position is K-1 seconds; when the predicted time threshold is reached, , the result is always greater than 0, the output is the predicted remaining time to reach the target pile insertion position is > predicted time threshold.

[0014] Further, S7 includes the following steps: G1: according to the motion prediction result, when the platform reaches the target pile insertion position, the pile leg enters the mud to realize the position and the heading is kept, G2: after the pile insertion is completed, the dynamic positioning operation is released, and the subsequent pressure balancing and leveling operations are completed by the pile leg lifting device.

[0015] Further, the self-elevating offshore platform with insufficient transverse propulsion capacity compensates for the insufficient transverse positioning by the motion prediction and longitudinal adjustment, ensuring the accuracy of the pile insertion operation.

[0016] The one or more technical solutions in the embodiments of the present application have at least one of the following technical effects: By motion prediction and longitudinal adjustment, the insufficient transverse propulsion capacity of the platform is compensated, and accurate pile insertion is achieved.

[0017] The motion prediction model provides a position sequence and a remaining time for a certain time threshold in the future, providing real-time guidance for the operator.

[0018] Combined with the dynamic positioning of the fixed-point positioning, the manual operation mode and the state estimation, an efficient auxiliary pile insertion process is realized.

[0019] In summary, the method can overcome the difficulty of pile insertion in the fixed-point mode caused by the insufficient transverse capacity of the platform in the strong current, and by combining different operation modes of dynamic positioning and state estimation output, the motion prediction result of the platform in the future is given and the auxiliary pile insertion operation is guided, which has high engineering application value.

[0020] Additional aspects and advantages of the application will be described in part in the description which follows, and in part will become apparent to those skilled in the art from the description, or by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0022] Figure 1 is a flow chart of a method for assisting pile driving of a self-elevating offshore platform according to an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are part of, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application. The following embodiments are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0024] The self-elevating offshore platform pile driving method according to the present application will be described below. Figure 1 The self-elevating offshore platform pile driving method according to the present application will be described below.

[0025] The present application is directed to a situation that a self-elevating offshore platform may not be able to normally pile in a dynamic positioning mode due to insufficient transverse capacity when piling. A method for assisting pile driving by motion prediction of a dynamic positioning system is proposed. The method combines the fixed-point positioning, manual control mode and state estimation output of the dynamic positioning to design an operation method for assisting pile driving, which can guide the self-elevating offshore platform to complete pile driving even when the flow velocity is large.

[0026] The present application provides a self-elevating offshore platform pile driving method, comprising: S1: obtaining target pile driving position and target pile driving heading information, setting the heading of the platform as the target pile driving heading when the platform moves to a distance within a first threshold range of the target pile driving position, and collecting the drift speed and drift direction of the platform; comprising the following steps: B1: starting the fixed-point positioning mode of the dynamic positioning in a radius of 50 meters around the target pile driving position , and recording the coordinates in the geodetic coordinate system as ; B2: setting the heading of the platform as the target pile driving heading ; B3: after the platform rotates to the target pile driving heading and the drift speed is stable under the action of the environmental force, recording the transverse speed and the transverse direction at this time. When the platform drifts to the port side, record ; when the platform drifts to the starboard side, record . ​​

[0027] The platform is preliminarily controlled near the target pile insertion position through the fixed-point positioning mode, to provide a basis for subsequent calculation of the initial maneuvering target position. The drift speed and direction are recorded to quantify the influence of environmental forces on the lateral movement of the platform, to provide key input data for movement prediction. The heading of the platform is adjusted to the target pile insertion heading to ensure the attitude consistency of the platform in the subsequent pile insertion process.

[0028] S2: obtaining the initial maneuvering target position of the platform according to the target pile insertion position, the target pile insertion heading, the water depth of the target pile insertion position, the draft of the platform and the pile insertion speed; the initial maneuvering target position is upstream of the target pile insertion position; comprising the following steps: C1: the specific steps include: obtaining the water depth of the target pile insertion position, the draft of the platform and the pile insertion speed information; calculating the pile insertion time as formula (1): (1) In the formula, is the pile insertion speed, is the water depth, is the draft of the platform.

[0029] C2: the initial maneuvering target position in the geodetic coordinate system The coordinate is denoted as , and the calculation is as follows: (2) The movement time window of the platform from the initial maneuvering target position to the target pile insertion position is determined by calculating the pile insertion time; the initial maneuvering target position takes into account the drift speed and direction of the platform, to ensure that the platform can reach the target pile insertion position through natural drift and longitudinal adjustment in the case of insufficient lateral propulsion capacity; a clear starting point is provided for the positioning and movement prediction of the subsequent dynamic positioning system.

[0030] S3: adjusting the heading of the platform and moving to the initial maneuvering target position, and when the platform moves to the initial maneuvering target position, adjusting the heading of the platform to the target pile insertion heading; comprising the following steps: D1: in the fixed-point positioning mode, setting the target position of the platform as the initial maneuvering target position , and setting the target heading of the platform as ; is the opposite direction of , and this setting ensures that the platform can move to the initial maneuvering target position upstream of the target pile insertion position, to reach the target pile insertion position through the subsequent combined action of longitudinal adjustment and lateral movement of the platform.

[0031] D2: after the platform moves to the target position and the target heading set in D1, setting the target heading of the platform as the target pile insertion heading .

[0032] Ensure the platform from a known, optimized starting position to start the spud job, reduce the complexity of subsequent adjustment. Adjust the heading to the target spud heading, provide the correct platform attitude for subsequent spud operations, and still maintain a relatively stable position in the case of insufficient lateral propulsion capacity.

[0033] S4: Establish a low-frequency motion prediction model of the platform in the lateral direction, use the current state estimation value as the initial state for motion prediction, and output the position prediction sequence in the future period of time; adjust the longitudinal position of the platform based on the position prediction sequence, so that the trajectory of the position prediction sequence passes through the target spud position; Comprising the following steps: E1: Establish a dynamic positioning motion prediction mathematical model, in this invention, it is considered that the longitudinal and heading propulsion capacity of the platform is sufficient to resist environmental forces, and the lateral capacity is insufficient for motion prediction and auxiliary spud, so only the lateral motion is predicted. And because the high-frequency motion of the ship caused by the first-order wave force is reciprocating motion, this invention only predicts low-frequency motion. The dynamic positioning motion prediction mathematical model established is a simplified form of the low-frequency dynamics model in the state estimation model as shown in formula (3): (3) In the formula, and are the north position and east position of the platform in the geodetic coordinate system, represents the first derivative of n, that is, the north acceleration; represents the first derivative of e, that is, the east acceleration; is the transverse velocity; represents the first derivative of , that is, the transverse acceleration; is the mass of the platform, is the transverse hydrodynamic acceleration derivative; is the transverse hydrodynamic velocity derivative; is the transverse thrust generated by the propeller; is the transverse wind load; and are the north and east environmental disturbance loads, respectively.

[0034] In the above model, the predicted state vector is a 3-dimensional state vector; E2: Based on the model in E1, motion prediction is performed, outputting 1 position per second, outputting a geodetic coordinate system position sequence within 30 minutes, the initial value of the prediction uses the state estimation value output by the current dynamic positioning control period, and the transverse thrust, transverse wind load and environmental disturbance load also use the calculation results used by the state estimation.

[0035] E3: Longitudinal motion uses the hand-operated mode of dynamic positioning, adjusts the platform's fore-aft position through the hand-operated lever, and makes the predicted position pass through the target pile insertion position. The specific operation is as follows: E31: Calculate the target pile insertion position The vertical foot on the straight line where the predicted position sequence is located , The coordinates in the geodetic coordinate system , which are obtained by solving equation set (4) (4) In the formula, is the coordinates of the first point of the predicted position sequence is the coordinates of the last point of the predicted position sequence .

[0036] E32: Calculate the vector The coordinates in the geodetic coordinate system , which are calculated using formula (5) (5) The geodetic coordinate system takes the pile target point as the origin, with x pointing north and y pointing east; E33: Calculate the vector The coordinates in the platform coordinate system , which are calculated using formula (6) (6) The origin of the platform coordinate system is the center of gravity of the berth, with x pointing towards the bow and y pointing to the right side; E34: Adjust the platform's fore-aft position according to When , use the hand-operated lever to move the platform forward; when , use the hand-operated lever to move the platform backward.

[0037] The mathematical model predicts the platform's lateral motion trajectory, providing the operator with a decision basis for the pile insertion timing. Through the longitudinal hand-operated mode, the platform's position is adjusted in real time to compensate for the lack of lateral propulsion capacity, ensuring that the platform's trajectory can accurately pass through the target pile insertion position. The prediction results provide the operator with an intuitive motion trend, reducing the blindness of manual operation.

[0038] S5: While maintaining the continuous output of the motion prediction, start the pile leg insertion operation, and monitor the remaining time, water depth, and pile leg lowering length to reach the target pile insertion position; including the following steps: F1: Calculate the remaining time to reach the target pile insertion position, ​The remaining time to reach the target pile insertion position is the time required for the berth position to move to the target pile insertion position output in the motion prediction; The calculation step comprises: F11: In the loop function of the motion prediction, the coordinates of the current predicted position in the geodetic coordinate system are calculated The north and east deviations of the target pile insertion position are respectively recorded as And The coordinates of the last predicted position in the geodetic coordinate system are calculated The north and east deviations of the target pile insertion position are respectively recorded as And : (7) In the formula, K and K-1 represent the Kth and K-1th in the prediction sequence respectively.

[0039] F12: Calculate the lateral deviation of the current predicted position and the target pile insertion position in the platform coordinate system, recorded as And calculate the lateral deviation of the last predicted position and the target pile insertion position, recorded as : (8) F13: Calculate the remaining time for the output prediction to reach the target pile insertion position: If , the remaining time for the output prediction to reach the target pile insertion position is K-1 seconds; if until the end of the prediction loop function, The result is always greater than 0, then the remaining time for the output prediction to reach the target pile insertion position is > 30 minutes.

[0040] F2: Continuously monitor the water depth and pile leg lowering length using the water depth sensor and pile leg monitoring system.

[0041] Through continuous pile driving and real-time monitoring, it is ensured that the pile leg lowering process is synchronized with the platform motion. The remaining time calculation provides accurate pile insertion timing for the operator, optimizing the operation efficiency. Real-time monitoring of water depth and pile leg lowering length ensures accurate preparation before the pile leg touches the bottom.

[0042] S6: When the platform motion is within the second threshold range from the target pile insertion position, the platform is decelerated by using the friction between the pile leg and the seabed; The pile leg touching the bottom increases the friction between the pile leg and the seabed, which decelerates the platform. It needs to be noted that whether the pile leg touches the bottom is judged according to the vertical load of the pile leg measured by the pile leg monitoring system.

[0043] When the pile legs contact the seabed, the vertical load of the pile legs will have a significant positive and negative sign change, at this time the force of the pile legs on the platform changes from the downward force (gravity, buoyancy difference) to the upward support force.

[0044] By the friction between the pile legs and the seabed, the drift speed of the platform in the case of insufficient lateral propulsion capacity is effectively slowed down. The timing of the pile legs touching the bottom is accurately judged by the load change, which provides guarantee for subsequent pile insertion into the mud. The deceleration process avoids missing the target pile insertion position due to the too fast drift speed of the platform.

[0045] The second threshold value in this step is adjusted according to the lateral displacement speed Adjustment is made, and the driver can adjust it according to the specific situation. The size of the second threshold value can be adjusted by controlling the pile legs and using the friction between the pile legs and the seabed.

[0046] S7: When the platform reaches the target pile insertion position, the pile legs are controlled to enter the mud, and the position and heading of the platform are kept.

[0047] The method comprises the following steps: G1: According to the motion prediction result, when the platform reaches the target pile insertion position, the pile legs are made to enter the mud to realize the position and heading keeping. The motion prediction result of the dynamic positioning process assists the pile leg lifting device to perform pile insertion.

[0048] G2: After the pile insertion is completed, the dynamic positioning operation is released, and subsequent operations such as ballast and leveling are completed by the pile leg lifting device.

[0049] The pile legs entering the mud ensure the stability and heading keeping of the platform at the target pile insertion position, and complete the pile insertion task. After the dynamic positioning is released, the pile leg lifting device takes over the subsequent operation, ensuring that the platform enters a stable working state; which marks the successful completion of the pile insertion operation and lays a foundation for subsequent sea work (such as drilling and installation).

[0050] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for assisting pile driving of a self-elevating offshore platform by dynamic positioning motion prediction, characterized in that, S1: obtaining a target pile driving position, a target pile driving heading, water depth, platform draft and pile driving speed, setting the platform heading to the target pile driving heading when the platform moves to a distance within a first threshold range from the target pile driving position, collecting the drift speed and drift direction of the platform; S2: obtaining an initial maneuver target position of the platform according to the target pile driving position, the target pile driving heading, the water depth, the platform draft and the pile driving speed; S3: adjusting the platform heading and moving to the initial maneuver target position, and adjusting the platform heading to the target pile driving heading when the platform moves to the initial maneuver target position; S4: establishing a low-frequency motion prediction model of the platform, performing motion prediction based on the low-frequency motion prediction model, and outputting a position prediction sequence in a future period of time; adjusting the longitudinal position of the platform based on the prediction sequence so that the trajectory of the position prediction sequence passes through the target pile driving position; S5: while the motion prediction continues to output, starting the pile leg driving operation, and monitoring the remaining time to reach the target pile driving position, the water depth and the pile leg lowering length; the remaining time to reach the target pile driving position is the time required for the platform position output in the motion prediction to move to the target pile driving position; S6: when the platform moves to a distance within a second threshold range from the target pile driving position, judging whether the pile leg has touched the bottom, and using the friction between the pile leg and the seabed to slow down the platform; S7: when the platform reaches the target pile driving position, controlling the pile leg to enter the mud, realizing the retention of the platform position and heading, and terminating the dynamic positioning operation.

2. The method for assisting pile driving of a self-elevating offshore platform by dynamic positioning motion prediction according to claim 1, characterized in that, S1 includes the following steps: B1 : at the target pinning location a point positioning mode of opening the active force positioning in the radius threshold range, record the geodetic coordinate system coordinates as ; B2: Set platform heading Targeted to plug the bow ; B3: the platform is to be rotated to the target plugging bow direction , and the lateral drift speed is recorded after the drift speed is stable under the action of the environmental force and the lateral drift direction ; When the platform drifts to port, record When the platform drifts to starboard, record .

3. The method for assisting pile driving of a self-elevating offshore platform by dynamic positioning motion prediction according to claim 1, characterized in that, S2 includes the following steps: C1: Obtain target spud position water depth, platform draft and spud down speed information; calculate spud down time As formula (1): Formula (1) wherein is the speed of the pile, is the water depth, is the draft of the platform; C2: Initial maneuvering target position in geodetic coordinate system The coordinate is denoted and is calculated as in equation (2): Formula (2) the initial maneuver target position is upstream of the target pile driving position.

4. The method for assisting pile driving of a self-elevating offshore platform by dynamic positioning motion prediction according to claim 1, characterized in that, S3 includes the following steps: D1: in the point positioning mode, set the target position of the platform as the initial maneuvering target position , set the target heading of the platform as ; D2: the platform moves to the target position and target heading set in D1, and sets the target heading of the platform as the target pile driving heading .

5. The method for assisting pile driving of a self-elevating offshore platform by dynamic positioning motion prediction according to claim 1, characterized in that, S4 includes the following steps: E1: establishing a dynamic positioning motion prediction mathematical model, which is a simplified form of the low-frequency dynamics model in the state estimation model as formula (3): Formula (3) where and are the north and east positions in the platform ECEF coordinate system, respectively; denotes the first derivative of n, i.e. the north acceleration; denotes the first derivative of e, i.e. the east acceleration; is the cross-range velocity; denotes the first derivative of , i.e. the cross-range acceleration; is the platform mass, is the cross-range hydrodynamic acceleration derivative; is the cross-range hydrodynamic velocity derivative; is the cross-range thrust generated by the thrusters; is the cross-range wind load; and are the north and east environmental disturbance loads, respectively; the predicted state vector in the model is the 3-dimensional state vector; E2: based on the model in E1, performing motion prediction, outputting 1 position per second, outputting a sequence of positions in the geodetic coordinate system within a prediction time threshold, using the state estimation value output in the current dynamic positioning control period as the prediction initial value, and using the calculation results of the state estimation as the lateral thrust, lateral wind load and environmental disturbance load; E3: the longitudinal motion uses the hand-operated mode of dynamic positioning, the platform forward and backward position is adjusted through the hand-operated lever, and the predicted position passes through the target pile driving position.

6. The method for assisting pile driving of a self-elevating offshore platform by dynamic positioning motion prediction according to claim 5, characterized in that, E3 is specifically operated as: E31: Calculate target pegging position Foot of perpendicular on the straight line on which the sequence of predicted positions lies , Coordinates in the geodetic coordinate system By solving the system of equations (4) Formula (4) Where, is the first point in the forecast position sequence The coordinates of The last point in the forecast position sequence coordinates; E32: Calculate the vector using formula (5) Coordinates in the terrestrial coordinate system , Formula (5) The earth coordinate system takes the target pile insertion point as the origin, with x pointing north and y pointing east. E33: Compute the vector using formula (6) Coordinates in the platform coordinate system , Formula (6) The origin of the platform coordinate system is the center of gravity of the platform, with x pointing forward and y pointing to the right side. E34: According to Adjust the front and back position of the platform, when the platform moves forward; when the platform moves backward.

7. The method of claim 1, wherein the method further comprises: S5 comprises the following steps: F1: calculating the remaining time to reach the target pile insertion position, and F2: continuously monitoring the water depth and the pile leg lowering length using the water depth sensor and the pile leg monitoring system.

8. The method of claim 1, wherein the method further comprises: The step of calculating the remaining time to reach the target pile insertion position comprises: F11: Calculate the coordinates of the current predicted position in the geodetic coordinate system and eastward deviation of the target drilling position, respectively, are recorded as and ; and calculate the coordinates of the last predicted position in the geodetic coordinate system and eastward deviation of the target drilling position, respectively, are recorded as and : Formula (7) wherein K and K-1 represent the Kth and K-1th in the prediction sequence, respectively. F12: the lateral deviation between the current predicted position and the target splicing position in the coordinate system of the computing platform, denoted as ; and the lateral deviation between the last predicted position and the target splicing position is calculated, denoted as : Formula (8); F13: calculating the remaining time to reach the target pile insertion position, If the output is the predicted time to reach the target spiking location. If the result is always greater than 0, the output is the predicted time to reach the target spiking location > the predicted time threshold.

9. The method of claim 1, wherein the method further comprises: S7 comprises the following steps: G1: based on the motion prediction result, when the platform reaches the target pile insertion position, the pile leg mud entry implementation position and the heading are kept, G2: after the pile insertion is completed, the dynamic positioning operation is released, and the subsequent ballast and leveling operations are completed by the pile leg lifting device.

10. The method of claim 1, wherein the method is suitable for self-elevating offshore platforms with insufficient lateral propulsion capacity, and the motion prediction and longitudinal adjustment compensate for the insufficient lateral positioning to ensure the accuracy of the pile insertion operation. ​

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