Ship crane heave compensation system and heave compensation method, device and apparatus

Abstract

The application provides a heave compensation system, method, device and equipment for a ship crane. The heave compensation method comprises the following steps: obtaining a ship body heave signal measured by a heave measuring unit, and obtaining a prediction signal of ship body motion according to the ship body heave signal; performing displacement conversion on the prediction signal of the ship body motion to obtain a vertical integrated heave displacement of a cable extension point; generating a feedforward compensation amount according to the vertical integrated heave displacement; obtaining a tracking error by subtracting a load displacement fed back by a feedback control chain from an instruction displacement; obtaining a basic control amount according to the tracking error; performing superposition operation on the feedforward compensation amount and the basic control amount to obtain a total control amount, and outputting the total control amount to a winch to drive the winch to wind or unwind the cable. The heave compensation method has strong anti-disturbance ability, high control precision and fast dynamic response speed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heave compensation of marine cranes, and in particular to a heave compensation system, method, device and equipment for marine cranes. BACKGROUND

[0002] In marine resource exploration and marine information acquisition, a winch is the most widely used equipment for deploying and recovering underwater towed bodies. The winch is generally installed on a ship platform. Due to the existence of sea waves, the ship heaves violently, so that the cable connecting the winch and the underwater towed body is frequently impacted, and the operating depth of the underwater towed body frequently changes. For a system that needs to have a depth-keeping operation, or needs to weaken the impact of the cable, a winch with heave compensation function is needed.

[0003] There are various means to achieve the heave compensation function of the marine winch, including heave compensation through mechanical mechanisms and pneumatic hydraulic structures, or heave compensation through an electric control system, or a combination of the heave compensation structure and the electric control system. Purely relying on the electric control system for heave compensation has the advantage of simple structure, but how to respond to heave in time, and the long-term reliable operation in complex marine environment, etc., put higher design requirements on the control system. SUMMARY

[0004] The present application aims to solve at least one of the technical problems existing in the prior art, and provides a heave compensation system, method, device and equipment for marine cranes.

[0005] In a first aspect, the present application provides a heave compensation method, including the following steps:

[0006] Obtaining a ship heave signal measured by a heave measuring unit, and obtaining a ship motion prediction signal according to the ship heave signal;

[0007] Converting the ship motion prediction signal into displacement to obtain a vertical integrated heave displacement of a cable extension point;

[0008] Generating a feedforward compensation amount according to the vertical integrated heave displacement;

[0009] Subtracting an instruction displacement from a load displacement fed back by a feedback control chain to obtain a tracking error;

[0010] Obtaining a basic control amount according to the tracking error;

[0011] Superimposing the feedforward compensation amount and the basic control amount to obtain a total control amount, and outputting the total control amount to the winch to drive the winch to deploy or recover the cable.

[0012] In some embodiments, a hull heave signal measured by the heave measuring unit is obtained, and a prediction signal of the hull motion is obtained according to the hull heave signal, including:

[0013] a history vertical displacement compensation amount at a plurality of time points in the past is obtained;

[0014] a polynomial describing the heave motion is obtained according to the history vertical displacement compensation amount at the plurality of time points in the past;

[0015] a prediction signal of the hull motion at a future time point is obtained through the polynomial.

[0016] In some embodiments, the polynomial expression Y(j)=a+b*(2+0.1*j)+c*(2+0.1*j)*(2+0.1*j)+d*(2+0.1*j)*(2+0.1*j)*(2+0.1*j),

[0017] wherein a=0.167*(3*x0+4*x1-x2);

[0018] b=0.167*(y2-y1);

[0019] c=0.056*(5*x2-3*x0-2*x1);

[0020] d=0.167*(8*y1-y2);

[0021] x0=data3;

[0022] x1=0.5*(data4+data2);

[0023] y1=0.5*(data4-data2);

[0024] x2=0.5*(data5+data1);

[0025] y2=0.5*(data5+data1);

[0026] data1, data2, data3, data4, data5, data6 are respectively history vertical displacement compensation amounts at the last 6 time points, and j defines a discrete time point at a future time point.

[0027] In some embodiments, the heave compensation method of the present application further includes the following steps: a feedback control chain obtains a tension signal on the cable and a length of the cable extension point to the load, and obtains a load displacement according to the tension signal, the vertical comprehensive heave displacement, and the length of the cable extension point to the load.

[0028] In some embodiments, the feedback control chain comprises a state observer and an operation module, the state observer obtains an estimated value of the cable length variation according to the length of the cable from the cable extension point to the load and the tension of the cable, sums the estimated value of the cable length variation with the vertical integrated heave displacement and subtracts the length of the cable from the cable extension point to the load to obtain a load displacement, and feeds back the load displacement to the comparison module.

[0029] In some embodiments, the method further comprises the following step before the displacement conversion of the predicted signal of the ship motion: performing a smooth interpolation processing on the predicted signal of the ship motion.

[0030] In some embodiments, the predicted signal of the ship motion is obtained according to the ship heave signal, and specifically comprises: superimposing the ship heave signal with an inertial navigation measurement error to obtain a first superimposed signal, and obtaining the predicted signal of the ship motion according to the first superimposed signal, wherein the inertial navigation measurement error comprises a measurement element error and a lever arm error.

[0031] In some embodiments, the displacement conversion of the predicted signal of the ship motion comprises: superimposing the predicted signal of the ship motion with a wave prediction error to obtain a second superimposed signal, and performing the displacement conversion on the second superimposed signal to obtain an integrated heave displacement, wherein the wave prediction error comprises a roll error, a pitch error and a heave error.

[0032] In some embodiments, the feedforward compensation quantity is generated according to the vertical integrated heave displacement, and specifically comprises: inputting the vertical integrated heave displacement into a feedforward controller to obtain the feedforward compensation quantity.

[0033] The transfer function of the feedforward controller is:

[0034]

[0035] wherein, is a motor torque constant, is a torque coefficient, is a motor electrical constant, is a winch radius.

[0036] In some embodiments, after the total control quantity is obtained, the method further comprises the following step: subtracting the total control quantity from a rotation speed feedback signal to obtain an error signal, generating a motor control signal according to the error signal, and adjusting the rotation speed / torque of the motor of the winch.

[0037] The motor control signal is generated according to the error signal, and specifically comprises: inputting the error signal into a rotation speed controller to obtain the motor control signal.

[0038] The transfer function of the rotation speed controller is:

[0039]

[0040] wherein, is a motor torque constant, is a moment coefficient, is a motor electrical constant.

[0041] In a second aspect, the present disclosure also provides a heave compensation system, comprising: a main control chain, a feedforward compensation chain, and a feedback control chain, the feedforward compensation chain comprising a feedforward prediction module, a comprehensive heave displacement conversion module, and a feedforward controller arranged in sequence, the feedforward prediction module being configured to receive a ship body heave signal measured in real time by a heave measuring unit, and obtain a prediction signal of ship body motion according to the ship body heave signal, the comprehensive heave displacement conversion module being configured to convert the prediction signal of ship body motion into a vertical comprehensive heave displacement of a cable extension point, and the feedforward controller being configured to generate a feedforward compensation amount according to the vertical comprehensive heave displacement, and superimpose the feedforward compensation amount on the main control chain.

[0042] The main control chain comprises a first comparison module, a trajectory tracking controller, a main superimposition module, and an actuator arranged in sequence, the first comparison module being configured to subtract an instruction displacement from a load displacement fed back by the feedback control chain to obtain a tracking error, the trajectory tracking controller being configured to obtain a basic control amount according to the tracking error, and the main superimposition module being configured to superimpose the feedforward compensation amount output by the feedforward controller and the basic control amount to obtain a total control amount, and output the total control amount to the winch to drive the winch to wind or unwind the cable.

[0043] In some embodiments, the feedforward compensation chain further comprises a data processing module configured to perform a smoothing interpolation processing on the prediction signal of ship body motion, and output the prediction signal to the comprehensive heave displacement conversion module.

[0044] In some embodiments, the main control chain further comprises a second comparison module and a rotating speed controller, the second comparison module being configured to subtract the total control amount from a rotating speed feedback signal to obtain an error signal, and the rotating speed controller being configured to generate a motor control signal according to the error signal to adjust the rotating speed / torque of the motor of the winch.

[0045] In some embodiments, the feedback control chain comprises a state observer and an operation module, the state observer being configured to obtain an estimated value of cable length change according to the length of the cable extension point to the load and the tension of the cable, the operation module being configured to sum the estimated value of cable length change and the vertical comprehensive heave displacement, and subtract the length of the cable extension point to the load to obtain an estimated load displacement, and feed back the estimated load displacement to the comparison module.

[0046] In a third aspect, the present disclosure also provides an electronic device, comprising:

[0047] one or more processors;

[0048] a memory for storing one or more programs;

[0049] When the one or more programs are executed by the one or more processors, the one or more processors implement the method as claimed in the first aspect.

[0050] In a fourth aspect, the present disclosure also provides a heave compensation system for a ship-mounted crane, comprising:

[0051] a heave measuring unit for measuring a heave signal of a ship body and transmitting the heave signal of the ship body to a controller;

[0052] a crane for implementing the winding and unwinding of a cable and completing the lifting and lowering of a load, the crane being electrically connected to the controller;

[0053] a controller for implementing the method as claimed in any one of the first aspect.

[0054] The present application has at least the following beneficial effects:

[0055] The heave compensation device provided by the technical solution of the present disclosure comprises a main control chain, a feedforward compensation chain and a feedback control chain. The feedforward controller D(s) of the feedforward compensation chain compensates for the heave of the ship body and motion disturbance (such as the vertical / horizontal motion of the ship body caused by sea waves) in advance through comprehensive heave displacement filtering and B-spline interpolation, and actively offsets the effects of the disturbance before the disturbance affects the system. The state observer of the feedback control chain estimates the internal states such as the change in the length of the cable and the displacement of the load in real time, and provides accurate state feedback for the controller, thereby solving the problem that key variables are difficult to measure directly. The closed-loop trajectory tracking controller G(s) of the main control chain further corrects the model deviation and unknown disturbance through the error closed loop of the command displacement-feedback displacement, and ensures that the load accurately tracks the target trajectory.

[0056] The heave change is the core disturbance of the vertical motion of the ship body (such as the up-down fluctuation of the top end of the crane caused by sea waves). The system realizes fast response through feedforward compensation and state observation. The “prediction-advance compensation” feature of the feedforward control, combined with the “real-time state estimation” of the state observer, makes the system respond more quickly to dynamic disturbances such as heave of the ship body and sudden change of the load. Even in the face of model parameter changes, the negative feedback mechanism of the closed-loop structure and the state observer can maintain the stability of the system.

[0057] In summary, the control system has a three-layer architecture of “feedforward advance compensation + state observation real-time correction + closed-loop tracking”, which not only ensures the anti-disturbance ability and control accuracy, but also has the ability to quickly respond to dynamic changes such as heave of the ship body. The “double-path” design of feedforward and feedback reduces the impact of single-link failure on overall control. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 A system block diagram of heave compensation control of one embodiment provided for the embodiments of the present disclosure;

[0059] Figure 2 A system block diagram of heave compensation control provided for another embodiment of the present disclosure;

[0060] Figure 3 A system block diagram of heave compensation control provided for still another embodiment of the present disclosure;

[0061] Figure 4 A whole flow chart of a prediction algorithm provided for the embodiments of the present disclosure;

[0062] Figure 5 A schematic diagram of a heave compensation system of a ship-mounted crane provided for one embodiment of the present disclosure;

[0063] Figure 6 A schematic diagram of a heave compensation system of a ship-mounted crane provided for another embodiment of the present disclosure; (including a fixed coordinate system and a moving coordinate system)

[0064] Figure 7 A heave displacement error response curve diagram;

[0065] Figure 8 A roll angle error response curve diagram;

[0066] Figure 9 A pitch angle error response curve diagram;

[0067] Figure 10 An actual vertical integrated heave displacement curve diagram;

[0068] Figure 11 An error response curve diagram;

[0069] Figure 12 An error response curve diagram. DETAILED DESCRIPTION

[0070] In order for those skilled in the art to better understand the technical solutions of the present application, the exemplary embodiments of the present application are described below in conjunction with the drawings, which include various details of the embodiments of the present application to help understanding, and should be considered only as exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Also, in order to be clear and concise, the description below omits the description of well-known functions and structures.

[0071] In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0072] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0073] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. "Coupled" or "connected" or similar terms are not restricted to physical or mechanical connections or associations, but can also include electrical connections, whether direct or indirect.

[0074] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.

[0075] Referring to Figures 1 to 3 The embodiments of the present application disclose a heave compensation method, comprising the following steps:

[0076] Obtaining a ship body heave signal measured by a heave measuring unit, and obtaining a predicted signal of ship body motion (a predicted signal of ship body motion of the next control period) according to the measured ship body heave signal;

[0077] Converting the predicted signal of ship body motion into displacement, to obtain a vertical integrated heave displacement of a cable extension point (such as but not limited to the top end of a crane);

[0078] Generating a feed-forward compensation amount according to the vertical integrated heave displacement;

[0079] Obtaining a tracking error by subtracting a load displacement fed back by a feedback control chain from an instruction displacement;

[0080] Obtaining a basic control amount according to the tracking error;

[0081] Superimposing the feed-forward compensation amount and the basic control amount to obtain a total control amount, and outputting the total control amount to a winch to drive the winch to wind or unwind the cable.

[0082] In order to weaken the disturbance caused by the displacement of the ship body, the attitude displacement compensation and the ship body speed compensation are used to weaken the influence on the heave. Since the original signal of the inertial navigation has a certain delay and the sampling rate is low, the polynomial feedforward prediction algorithm based on time sequence is designed, the motion trend of the current or future ship body can be derived according to the historical wave signal, and the system is controlled in advance through the feedforward controller to offset the adverse effects caused by the time delay and the large inertia characteristics.

[0083] In some embodiments, the heave compensation method further comprises the following steps: a feedback control chain obtains the tension signal of the cable and the length of the cable from the extension point to the load (or the release length of the cable), and obtains the load displacement according to the tension signal, the vertical integrated heave displacement and the length of the cable from the extension point to the load (or the release length of the cable).

[0084] In some embodiments, the feedback control chain comprises a state observer and a calculation module, the state observer obtains the estimated value of the length change of the cable according to the length of the cable from the extension point to the load and the tension of the cable, the calculation module sums the estimated value of the length change of the cable and the vertical integrated heave displacement and subtracts the length of the cable from the extension point to the load to obtain the load displacement (i.e. the estimated value of the load displacement), and feeds back the load displacement to the comparison module.

[0085] In other embodiments, the feedback control chain can also not have a state observer, but can collect the load displacement through the motor encoder or the encoder at the pulley. That is, the present application can also detect the angle of rotation of the motor through the motor encoder, and calculate the length of the cable in real time and the load displacement, or can detect the angle of rotation of the pulley through the encoder, and calculate the length of the cable in real time and the load displacement.

[0086] In some embodiments, the ship body heave signal measured by the heave measuring unit is obtained, and the prediction signal of the ship body motion is obtained according to the ship body heave signal, comprising:

[0087] The historical vertical displacement compensation amounts at the recent multiple time points are obtained;

[0088] The polynomial describing the heave motion is obtained according to the historical vertical displacement compensation amounts at the recent multiple time points;

[0089] The prediction signal of the ship body motion at the future time point is obtained through the polynomial.

[0090] In some embodiments, the polynomial expression cha_value[j]=a+b*(2+0.1*j)+c*(2+0.1*j)*(2+0.1*j)+d*(2+0.1*j)*(2+0.1*j)*(2+0.1*j),

[0091] wherein a=0.167*(3*x0+4*x1-x2);

[0092] b=0.167*(y2-y1);

[0093] c=0.056*(5*x2-3*x0-2*x1);

[0094] d=0.167*(8*y1-y2);

[0095] x0=data3;

[0096] x1=0.5*(data4+data2);

[0097] y1=0.5*(data4-data2);

[0098] x2=0.5*(data5+data1);

[0099] y2=0.5*(data5+data1);

[0100] data1, data2, data3, data4, data5, data6 are the historical vertical displacement compensation amounts, i.e. historical heave compensation calculation results, of the last 6 time points, and j defines a discrete time point in the future.

[0101] The heave compensation predicted displacement amount slash_cha=cha_value[j] at a certain time in the future (determined by j);

[0102] The predicted speed slash_vol=b+4*c+12*d;

[0103] The predicted acceleration slash_acc=2*c+12*d.

[0104] The heave compensation predicted displacement amount can be used to reversely deduce the ship motion signal at the time, such as the 6 signal key features of the heave measuring unit. The 6 signals of the heave measuring unit (especially Heave, Roll, and Pitch) are the "source data" for calculating real-time compensation amounts.

[0105] The present application obtains the rotation angle and translation distance of the ship body around the rotation angle and translation distance , the rotation angle and translation distance , the rotation angle and translation distance , and the rotation angle and translation distance After that, coordinate data in the fixed reference system is obtained through coordinate transformation.

[0106] According to the coordinate data in the fixed reference system, a heave displacement, i.e., a Z-axis position offset caused by heave motion, is calculated; and a vertical displacement compensation amount is obtained according to the heave displacement.

[0107] Ship motion data in the fixed reference system is obtained through coordinate transformation, including: constructing a rotation transformation matrix, rotating original motion system coordinates (Wheel_Point_m[0 / 1 / 2]) according to the rotation transformation matrix, adding a translation transformation vector to the rotated coordinates, and finally obtaining ship motion data in the fixed reference system Wheel_Point_f[0 / 1 / 2]. The subsequent calculation of delta_l (vertical difference between the fixed system and the motion system), heave_convert (heave displacement), and motion prediction based thereon are all based on the fixed reference system data.

[0108] lo=SQRT((Wheel_Point_m[0]-Top_Point_f[0])*(Wheel_Point_m[0]-Top_Point_f[0])+(Wheel_Point_m[1]-Top_Point_f[1])*(Wheel_Point_m[1]-Top_Point_f[1])+(Wheel_Point_m[2]-Top_Point_f[2])*(Wheel_Point_m[2]-Top_Point_f[2]))).

[0109] l=SQRT((Wheel_Point_f[0]-Top_Point_f[0])*(Wheel_Point_f[0]-Top_Point_f[0])+(Wheel_Point_f[1]-Top_Point_f[1])*(Wheel_Point_f[1]-Top_Point_f[1])+(Wheel_Point_f[2]-Top_Point_f[2])*(Wheel_Point_f[2]-Top_Point_f[2]))).

[0110] Fixed system and motion system vertical difference delta_l=Wheel_Point_f[2]-Wheel_Point_m[2].

[0111] Heave displacement heave_convert=A*delta_l. A is a proportional coefficient of the actual heave physical quantity. In some embodiments, A is 3.6.

[0112] The application also comprises: batch storing N (such as 6) historical vertical displacement compensation amounts, and automatically switching to a "calculation state" after being full, that is, obtaining a polynomial describing the heaving motion according to the historical vertical displacement compensation amounts of the latest N (such as 6) moments;

[0113] Obtaining a prediction signal of the ship body motion at a future moment through the polynomial.

[0114] Storing the historical vertical displacement compensation amounts at multiple moments into an array present_data in sequence, specifically:

[0115] When the system is in a "data saving state", the following operations are performed:

[0116] Storing the currently input historical vertical displacement compensation amount slash into the i-th position (i is the array index, starting from 0) of the array present_data.

[0117] Increasing the index i by 1 to prepare for storing the next slash value.

[0118] Judging whether 6 data have been stored:

[0119] If i < 6 (not full), keeping the "data saving state", continuing to receive and store the next slash value. If i≥ 6 (6 data are stored), switching the state to the "calculation state", that is, obtaining a polynomial describing the heaving motion according to the historical vertical displacement compensation amounts of the latest N (such as 6) moments.

[0120] Marking "data full" with a flag slash_flag, for other logics (such as a calculation module) to judge whether the processing can be started.

[0121] The above method of the application realizes "sliding window type data acquisition", through the i counting, ensuring that the present_data array always stores "the slash data of the latest 6 moments" (from present_data[0] to present_data[5]); after being full, automatically triggering the state switching, connecting the "data calculation" process, which is the key link of the "acquisition-processing" closed loop, ensuring that the subsequent calculation has enough historical data support (such as the 6 data used for fitting the polynomial in the code).

[0122] The application also controls the number of "future motion prediction" through a counting variable j, and updates the historical data array after completing the prediction, forming a closed loop of "calculation->update->recalculation". The specific analysis is as follows:

[0123] j is the "index of future time" (range 1~M), corresponding to M discrete future time points (e.g. t=2.1 to t=3.0, interval 0.1 unit time) that need to be predicted.

[0124] When j < M (prediction of M time points not completed): j is incremented by 1, state.calculate state is maintained, and the prediction value (cha_value[j]) of the next future time point is continued to be calculated.

[0125] When j >= M (prediction of M time points completed): theoretically switch to state.update state (update data).

[0126] In some embodiments, M is 10.

[0127] Regardless of whether j is less than M (e.g. M is 10), it will eventually enter the state.update state (redundant logic in code design to "ensure timely update of data", to avoid state being stuck due to abnormal j counting).

[0128] The state.update state (update data) includes: updating the historical data array to prepare for the next round of prediction.

[0129] Array left shift: through the loop of k=1~4, the elements of index 1~4 in present_data are updated to the values of index 2~5 (i.e. "left shift one bit"), which is equivalent to discarding the oldest historical data (present_data[0] because it is no longer used in subsequent calculations).

[0130] Supplement new data: store the latest input data slash in present_data[5] (the end of the array), so that present_data always maintains "the latest 6 time points of historical data".

[0131] Reset the count and state: j is reset to 1 (start calculating the prediction of the next 10 future time points), and the state is switched back to state.calculate to start the next round of prediction.

[0132] The above process of the present application is: using the current 6 historical data, calculate the prediction values of 10 future time points → discard the oldest data, supplement new data, reset the count → return to state.calculate, i.e. continue to predict the next batch of 10 future time points based on the updated 6 historical data.

[0133] The above scheme of the present application realizes continuous and real-time prediction of ship body movement through "rolling update historical data + repeated prediction of future time", controls the prediction value of 10 future times in each calculation, and enters the data update state after completion; state.update maintains the latest 6 historical data through "left array + supplement of new data", and continues the next round of prediction after resetting the count; the whole forms a closed loop of "real-time data -> future prediction -> data update", guaranteeing the continuity and timeliness of the movement prediction.

[0134] Due to the roll and pitch of the ship, the heave displacement of each point on the ship is not the same. The inertial measurement unit for measuring the change of the ship pose is usually installed on the deck rather than the top of the crane, so a corresponding coordinate transformation is needed to convert the data measured by the inertial measurement unit into the vertical heave displacement of the top of the crane, otherwise there will be a large error.

[0135] In the system, the real-time attitude of the ship movement is read through the inertial navigation to obtain the real-time data of the wave disturbance. The wave disturbance is acting on the six degrees of freedom of the ship, including the roll, pitch and heave of the ship. We need to obtain the disturbance of the wave on the vertical direction to the cable contraction point through conversion.

[0136] The system needs to determine the mathematical relationship between the cable length and the ship attitude through the motion law of the inertial navigation measurement data, and establish two coordinate systems for the convenience of calculation, as shown in Figure 6 .

[0137] The motion coordinate system P is fixed to the ship and moves with the ship. The origin of the coordinate system coincides with the origin of the inertial navigation, and is simply referred to as the dynamic system or body coordinate system; the fixed coordinate system O is relatively static with respect to the earth, and is simply referred to as the static system or fixed system. The dynamic coordinate system coincides with the static coordinate system at the initial position.

[0138] Suppose that the inertial measurement unit measures the rotation angle of the ship body around is , the translation distance is , the rotation angle around is , the translation distance is , the rotation angle around is , and the translation distance is . The motion attitude of the ship body at this time is obtained, and the coordinate system is established with the position of the inertial measurement unit after movement as the origin. The rotation transformation matrix from the coordinate system to the coordinate system .

[0139]

[0140] For the convenience of writing, For The abbreviation of, For The abbreviation of.

[0141] The translation vector from the coordinate system To the coordinate system Is:

[0142]

[0143] Let point M be the position of the cable contraction point, the coordinates of M in the coordinate system P are The ship body can be regarded as a rigid structure, when point Moves to point , when point Moves to point , at this time, the coordinates of point In the coordinate system Is .

[0144] The application completes the transformation by "rotation matrix operation + translation amount superposition", so the coordinates of point In the coordinate system P (or static coordinate system) are:

[0145]

[0146] Let the obtained coordinates be At this time, the comprehensive vertical heave displacement of the cable contraction point affected by the ship body movement is:

[0147]

[0148] When static, the coordinates of point P in the coordinate system P are obtained , the coordinates of M point are , and the unit is meter.

[0149] When the ship moves to the coordinate system , there are As , As . Because the relative position of M point and the ship body is unchanged, the coordinates of M in the coordinate system Are .

[0150] The coordinates of point In the coordinate system At this time are , so the coordinates of point In the coordinate system P are:

[0151]

[0152] The obtained coordinates are . 1.82. If the heave of the installation position point is used to replace the heave of the rope point, we have

[0153] .

[0154] In some embodiments, the method further comprises the following step before the displacement conversion: smoothing and interpolating the predicted signal of the ship motion.

[0155] In some other embodiments, in a short time range, the vertical motion of the load affected by the ship motion can be regarded as a stationary random process, and the vertical displacement of the load obeys the following AR prediction model:

[0156] ,

[0157] wherein: the order of the AR model;

[0158] the autoregressive system of the AR model;

[0159] the white noise sequence.

[0160] The key to obtaining an AR prediction model with high accuracy is to estimate the autoregressive coefficients of the model . Here, we use the least squares method to estimate the vector of autoregressive coefficients based on historical data, and the estimated vector is .

[0161] After completing the estimation of the autoregressive coefficients , we need to obtain the order of the AR model to get the complete AR prediction model. The solution of the order is also called the order determination of the AR model.

[0162] The system selects the AIC criterion order determination method. First, we determine the maximum order of the model through offline estimation. Then, we take the order from 1 to , and bring each order into the AR model. We estimate the autoregressive coefficients in the model through the least squares method, and calculate the AIC criterion number of each model. Finally, we compare the sizes of all . When there is an that makes the When is the order of the AR prediction model.

[0163] After obtaining the autoregressive coefficients and order of the AR model through historical data, the predicted wave data of the next step is

[0164] When , there is

[0165] When , there is

[0166] When , there is

[0167] The overall flow chart of the wave prediction algorithm is shown in Figure 4 .

[0168] In some embodiments, after obtaining the total control quantity, the method further includes the following steps: subtracting the total control quantity from the speed feedback signal to obtain an error signal, generating a motor control signal according to the error signal, and adjusting the motor speed / torque of the winch. The speed feedback signal is the speed detected by the speed detection device.

[0169] In some embodiments, the motor control signal is generated according to the error signal, specifically including: inputting the error signal into a speed controller to obtain the motor control signal.

[0170] Speed controller design: according to the system model, for the speed loop of the servo motor, the open-loop transfer function is:

[0171]

[0172] In order to realize speed zero error and improve trajectory tracking accuracy, an integral link must be added in front of the load disturbance point, which should be included in the speed controller. Therefore, the speed controller adopts PI regulation, and the transfer function is:

[0173]

[0174] In order to let the controller zero point and the large time constant pole of the control object cancel out, the control parameters satisfy the condition:

[0175] , take , .

[0176] The speed loop .

[0177] ​​In some embodiments, the base control quantity is obtained according to the tracking error, specifically comprising: inputting the tracking error into a trajectory tracking controller to obtain the base control quantity.

[0178] Trajectory tracking controller design: further derive the open-loop transfer function of the load displacement outer loop:

[0179] .

[0180] Ignoring the influence of cable damping C, the frequency characteristics of the above formula are as follows:

[0181] .

[0182] The frequency characteristics of the above formula

[0183] .

[0184] The approximate condition for simplifying the above outer loop is that the cut-off frequency and .

[0185] Therefore, the open-loop transfer function of the simplified position outer loop is:

[0186]

[0187] The system can adopt proportional control, and the proportional coefficient can be taken as .

[0188] In some embodiments, the feedforward compensation quantity is generated according to the vertical integrated heave displacement, specifically comprising: inputting the vertical integrated heave displacement into a feedforward controller to obtain the feedforward compensation quantity.

[0189] According to the principle of structural invariance, the expression of the feedforward controller can be obtained from the mathematical model of the system as follows:

[0190]

[0191] The above feedforward controller can theoretically completely compensate for the interference caused by ship motion, but the above feedforward controller has a high order, and as a preferred embodiment, the third order term and the second order term can be omitted in actual design, and only the differential term is retained, so that the simplified feedforward controller is:

[0192] .

[0193] wherein, is the motor torque constant, is the motor electrical constant, total inertia of the winch unit (including winch, reducer, etc.) reduced to the motor output shaft, total viscous damping coefficient of the winch unit (including winch, reducer, etc.) reduced to the motor output shaft, winch radius, reduction ratio, cable damping coefficient, cable stiffness coefficient, equivalent static tension, equivalent mass, mechanical efficiency.

[0194] The residual of the control system is caused by multiple error sources, including inertial navigation measurement error , error caused by wave prediction , error caused by simplified feedforward controller and error caused by mechanism friction .

[0195] In some embodiments, according to the ship body heave signal, a predicted signal of ship body motion is obtained, specifically including: superimposing the ship body heave signal with the inertial navigation measurement error to obtain a first superimposed signal, and obtaining the predicted signal of ship body motion according to the first superimposed signal.

[0196] In some embodiments, the predicted signal of ship body motion is displacement reduced, specifically including: superimposing the predicted signal of ship body motion with the wave prediction error to obtain a second superimposed signal, and displacement reducing the second superimposed signal to obtain a comprehensive heave displacement.

[0197] The inertial navigation measurement error and the wave prediction error include roll error, pitch error and heave error. simplified feedforward controller. total Coulomb friction torque reduced to the motor output shaft.

[0198] The inertial navigation measurement error and the wave prediction error superimposed and input into the comprehensive heave displacement reduction equation are:

[0199] ,

[0200] wherein is the heave displacement reduction equation, is the ship pose quantity in ideal state, is the vertical comprehensive heave displacement of the cable extension point in actual state.

[0201] Further, the vertical total heave displacement of the cable extension point in the actual state Input to the simplified feedforward controller The error of the load displacement is:

[0202]

[0203] where is the vertical total heave displacement of the cable extension point in the ideal state; is the common fraction of the two transfer functions; is the rotational speed loop transfer function.

[0204] According to the system model, the error of the load displacement caused by the mechanism friction is:

[0205]

[0206] Since the error caused by the mechanism friction is independent of other error sources, the total error of the system is:

[0207] The inertial navigation measurement error includes measurement element error and lever arm error. The measurement element error is mainly caused by factors such as design principle, processing technology and assembly technology. The measurement element error of the inertial navigation selected by the system is: the roll angle and pitch angle measurement accuracy is ± 0.03°, and the heave measurement accuracy is 5 cm or 5%.

[0208] Causes of lever arm error: when the mass center of the inertial navigation does not coincide with the mass center of the ship, if the ship has angular motion, due to the Lever arm effect, the output of the accelerometer contains the lever arm error.

[0209] According to the data, due to the Lever arm effect, the specific force at the position of the inertial navigation and the specific force at the mass center of the ship have the following relationship:

[0210]

[0211] is the specific force at the position of the inertial navigation, is the specific force at the mass center of the ship, is the lever arm length, is the angular velocity of the ship relative to the inertial coordinate system.

[0212] The error term in it is .

[0213] Next, determine and The parameters can be approximated by assuming the ship's center of mass is at its geometric center. The inertial navigation system is located on the stern deck; establishing a rectangular coordinate system with the ship's center of mass as the origin yields the following results. .

[0214] According to available information, the roll amplitude of large ships under extreme conditions is 30°, and the roll period is... Where C is the roll period coefficient, which can be taken as 0.8, and B is the ship's beam, which can be taken as 14.28m. Taking the initial stable height as 0.8m, we obtain... By approximating the roll motion as a sinusoidal motion, the roll angle can be obtained. .

[0215] In extreme cases, the pitch amplitude of a large ship is 20°, and the pitch period is... ,in Let the pitch period coefficient be 0.55, and L be the ship length, which can be taken as 100m. The result is... By approximating the pitching motion as a sinusoidal motion, the roll angle can be obtained. .

[0216] Therefore, by differentiating the roll and pitch angles, we can calculate... , .

[0217] Substituting, we can calculate .

[0218] This causes a displacement error of .

[0219] In summary, the inertial navigation measurement error includes the measurement element error and the lever arm error. Therefore, the inertial navigation measurement error vector is:

[0220] .

[0221] In this system, since the original signal of inertial navigation has a certain delay and the sampling rate is low, we designed a time series-based polynomial feedforward prediction algorithm, which can deduce the current and even future motion trend of the ship based on historical signals, and compensate the control loop according to the delay of the system to offset the adverse effects of time delay and large inertia on system control.

[0222] In multi-step forecasting, subsequent forecast data are derived from previous forecast data, which can easily lead to the accumulation of errors when making long-term forecasts.

[0223] When historical data sequence When following a known forecasting model, the future step( Heave displacement Forecast value for:

[0224] (1) When , ;

[0225] (2) When , ;

[0226] where p is the order of the setting.

[0227] In the system, the sampling period T of the inertial navigation is 0.01s, and the response time of the whole system is about according to the experience estimation. Therefore, two-step prediction is selected, and the prediction time is 0.02s. By using matlab for simulation analysis, the heave displacement signal is taken as , the roll angle signal is taken as , and the pitch angle signal is taken as . The error response curves obtained by predicting the three signals respectively are shown in Figures 8 to 10 . It can be obtained from Figures 8 to 10 that the maximum value of the heave displacement error is 0.0125m, the maximum value of the roll angle error is , and the maximum value of the pitch angle error is .

[0228] As can be seen above, the wave prediction error includes the roll error, the pitch error and the heave error, so the wave prediction error vector is:

[0229] .

[0230] As can be seen from the foregoing error transmission analysis, the inertial navigation measurement error and the wave prediction error are superimposed and input into the comprehensive heave displacement conversion equation to obtain the vertical comprehensive heave displacement of the cable extension point in the actual state . Then it is input into the simplified feedforward controller, and finally acts on the load displacement .

[0231] Therefore, the vertical comprehensive heave displacement of the cable extension point in the actual state needs to be solved first. The ship pose in the ideal state is , and the heave motion amplitude is 1.5m. Due to the influence of the inertial navigation measurement error and the wave prediction error , the actual measured ship pose is:

[0232]

[0233] ​​From the coordinate transformation, in the ideal state, the cable contraction point moves to , the coordinates in the static coordinate system P are:

[0234]

[0235] The comprehensive vertical heave displacement of the cable contraction point affected by the ship motion is:

[0236]

[0237] In the actual situation, due to the existence of errors, the coordinates in the static coordinate system P are:

[0238]

[0239] The actual heave displacement obtained is:

[0240]

[0241] The vertical comprehensive heave displacement of the cable extension point in the actual state is as shown. Figure 11

[0242] Further, the vertical comprehensive heave displacement of the cable extension point in the actual state is input into the simplified feedforward controller , the error acting on the load displacement is:

[0243] ,

[0244] where .

[0245] The error response curve is shown in Figure 12 . From Figure 12 , the maximum error .

[0246] The above is the error generated by the wave signal with a heave change amplitude of 1.5 meters to the system, and the error generated by different wave signals to the system is related to the heave change amplitude, which will be analyzed below. Set the ship's pose in the ideal state as , and the heave motion amplitude is A.

[0247] In the ideal state, the cable contraction point moves to , the coordinates in the static coordinate system P are:

[0248] ​

[0249] In actual situation, The coordinates in the stationary coordinate system P are:

[0250] .

[0251] Obviously, the amplitude and the residual error are not a simple proportional relationship, here the invention uses matlab quadratic polynomial fitting , in which represents the amplitude.

[0252] The coulomb friction existing in each transmission mechanism will also affect the control accuracy of the system. For the system, the total coulomb friction can be expressed as:

[0253]

[0254] In the formula, is the friction torque converted to the output shaft of the servo motor, is the static friction converted to the output shaft, is the coulomb friction converted to the output shaft, is the angular velocity of the output shaft of the servo motor, is the Stribeck angular velocity.

[0255] After consulting the data analysis, we can get , , .

[0256] From the mathematical model, it can be derived that the error of the friction force of the mechanism acting on the load displacement is:

[0257]

[0258] Taking the rated speed of the motor , that is , the error value is m.

[0259] Through the above calculation and analysis, the total error of the system is .

[0260] When A=0.3m, the error is 0.047486m, which is less than 0.05m;

[0261] When A=0.5m, the error is 0.049486m, which is less than 0.05m;

[0262] When A=0.8m, the error is 0.065486m, and the residual error is 8.1%.

[0263] When A=1m, the error is 0.070486m, and the residual error is 7%;

[0264] When A=1.2m, the error is 0.076486m, and the residual error is 6.3%;

[0265] When A=1.5m, the error is 0.086m, and the residual error is 5.73%;

[0266] In summary, the system residual error meets the performance index requirements.

[0267] Based on the same inventive concept, the embodiment of the present application provides a heave compensation device, which comprises a main control chain, a feedforward compensation chain and a feedback control chain, the feedforward compensation chain comprises a feedforward prediction module, a comprehensive heave displacement conversion module and a feedforward controller which are sequentially arranged, the feedforward prediction module is used for receiving a ship body heave signal measured by a heave measuring unit in real time, and obtaining a prediction signal of ship body motion according to the ship body heave signal, the comprehensive heave displacement conversion module is used for performing displacement conversion on the prediction signal of ship body motion to obtain a vertical comprehensive heave displacement of a cable extension point, and the feedforward controller is used for generating a feedforward compensation amount according to the vertical comprehensive heave displacement and superimposing the feedforward compensation amount on the main control chain.

[0268] The main control chain comprises a first comparison module, a trajectory tracking controller, a main superimposition module and an actuator which are sequentially arranged, the first comparison module is used for subtracting a load displacement fed back by the feedback control chain from an instruction displacement to obtain a tracking error, the trajectory tracking controller is used for obtaining a basic control amount according to the tracking error, and the main superimposition module is used for superimposing and operating the feedforward compensation amount output by the feedforward controller and the basic control amount to obtain a total control amount and output the total control amount to a winch to drive the winch to wind or unwind the cable.

[0269] Since the active heave compensation device is a position interference type system, pure closed-loop control is difficult to achieve good control effect. Therefore, according to the principle of structural invariance, a feedforward controller is designed to suppress the ship motion interference. The ship motion signal measured by the inertial navigation attitude sensor is input into the AR prediction model after low-pass filtering to obtain the future motion trend of the ship body, which is superimposed into the closed-loop control loop through the feedforward controller and output to the control system to control the servo motor, so that the servo motor winds the cable in advance to eliminate other attitude disturbances.

[0270] In some embodiments, the feedforward compensation chain further comprises a data processing module, and the data processing module is used for performing smoothing interpolation processing on the prediction signal of ship body motion and outputting the prediction signal to the comprehensive heave displacement conversion module.

[0271] In some embodiments, the feedforward prediction module adopts a prediction algorithm based on AR model. The principle of AR prediction model is to read past ship motion data, to obtain the approximate curve of the signals by fitting, and finally to predict the ship in the future for a certain time through the fitted curve.

[0272] In some embodiments, the feedforward compensation chain further comprises a first feedforward superposition module, which is configured to superimpose the hull heave signal and the inertial navigation measurement error to obtain a first superposition signal, and to transmit the first superposition signal to the feedforward prediction module, which is configured to obtain a prediction signal of the ship body motion according to the first superposition signal, wherein the inertial navigation measurement error comprises a measurement element error and a lever arm error.

[0273] In some embodiments, the feedforward compensation chain further comprises a second feedforward superposition module, which is configured to superimpose the prediction signal of the ship body motion and the wave prediction error to obtain a second superposition signal, and to transmit the second superposition signal to the comprehensive heave displacement conversion module, which is configured to convert the second superposition signal into a comprehensive heave displacement, wherein the wave prediction error comprises a roll error, a pitch error and a heave error.

[0274] In some embodiments, the main control chain further comprises a second comparison module and a rotating speed controller, wherein the second comparison module is configured to subtract the total control quantity from the rotating speed feedback signal to obtain an error signal, and the rotating speed controller is configured to generate a motor control signal according to the error signal to adjust the rotating speed / torque of the motor of the winch.

[0275] The rotating speed of the drum of the winch is detected by a speed detection device.

[0276] The load displacement is obtained by the feedback control chain according to the tension signal, the vertical comprehensive heave displacement and the length of the cable extension point to the load.

[0277] In some embodiments, the feedback control chain comprises a state observer and an operation module, wherein the state observer is configured to obtain an estimated value of the length change of the cable according to the length of the cable extension point to the load , the tension F of the cable , the operation module is configured to sum the estimated value of the length change of the cable and the vertical comprehensive heave displacement and subtract the length of the cable extension point to the load to obtain an estimated load displacement (that is, the estimated value of the load displacement), and feed back the estimated load displacement to the comparison module. The present application is not limited to the above embodiments to obtain the load displacement, and the feedback load displacement can also be obtained by using existing methods.

[0278] In some embodiments, the feedforward prediction module is configured to obtain fitting curves of the signals by fitting according to historical ship motion data, and predict the ship in a future period of time through the fitting curves.

[0279] Based on the same inventive concept, see Figure 5 and Figure 6 The application also provides a ship crane heave compensation system, comprising:

[0280] a heave measuring unit configured to measure the ship body heave signal and transmit the ship body heave signal to the controller;

[0281] a crane configured to implement the winding and unwinding of the cable and complete the lifting and lowering of the load, and electrically connected to the controller;

[0282] a controller configured to implement the heave compensation method according to any one of the above embodiments.

[0283] In some embodiments, the crane comprises a winch configured to implement the winding and unwinding of the cable, and the winch is electrically connected to the controller.

[0284] In some embodiments, the crane further comprises a pulley block for guiding the cable, and the cable of the winch is connected to the load through the pulley block.

[0285] In some embodiments, the pulley block is mounted on a telescopic beam, and the telescopic beam is connected to a telescopic driving device for driving the horizontal movement of the telescopic beam, forming a telescopic mechanism, and the telescopic driving device is electrically connected to the controller.

[0286] In some embodiments, the ship crane heave compensation system further comprises a tension detection device configured to detect the tension on the cable and transmit the tension signal to the controller.

[0287] In some embodiments, the controller is further configured to receive a deployment instruction, control the telescopic beam of the telescopic mechanism to expand, and synchronously control the winch to pay out the cable, control the telescopic mechanism to stop running after the telescopic beam is expanded to the position, and control the winch to stop paying out the cable after the load reaches the preset depth.

[0288] The controller is further configured to receive a cable retraction instruction, control the winch to retract the cable, control the telescopic beam of the telescopic mechanism to retract after the load reaches the preset height, and synchronously control the winch to retract the cable, control the telescopic mechanism to stop running after the telescopic beam is retracted to the position, and control the winch to stop retracting the cable.

[0289] In order to ensure that the telescopic rod does not contact other objects during extension and retraction, the winch is cooperatively controlled during telescopic mechanism extension and retraction, that is, the laying control module of the application needs to realize cooperative control of the winch and the telescopic mechanism. The cable length L from the winch to the pulley, the linear displacement of the telescopic mechanism movement and the vertical distance H of the telescopic mechanism from the rotation center of the winch have a trigonometric function relationship as shown in the following formula. Figure 7 Figure 7 In the formula, M is the distance that the telescopic mechanism has moved; P is the distance of the next movement of the telescopic mechanism; L1 is the distance of the cable to the pulley; L2 is the distance of the cable to the pulley after the next movement of the telescopic mechanism is completed; Vj is the movement speed of the winch; and Vs is the movement speed of the telescopic mechanism.

[0290]

[0291] In the formula, M, H and T are known constants, which can be simplified as a, which can be simplified as b, that is, .

[0292] The relationship between the winch laying line speed and time T and the telescopic mechanism speed can be obtained from the above, and the winch output speed is given according to the above calculation result, so as to ensure that the winch laying line speed and the telescopic mechanism are synchronized, and the load is safe.

[0293] Based on the same inventive concept, the application also provides an electronic device, which comprises one or more processors, a memory, and one or more I / O interfaces. The memory stores one or more programs, and when the one or more programs are executed by the one or more processors, the one or more processors implement the heave compensation method in any of the above embodiments. The one or more I / O interfaces are connected between the processor and the memory and are configured to realize information interaction between the processor and the memory.

[0294] The processor is a device with data processing capability, including but not limited to a central processing unit (CPU) and the like; the memory is a device with data storage capability, including but not limited to a random access memory (RAM, more specifically SDRAM, DDR, etc.), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), and a flash memory (FLASH); and the I / O interface (read-write interface) 103 is connected between the processor and the memory and can realize information interaction between the processor and the memory, including but not limited to a data bus (Bus) and the like.

[0295] In some embodiments, the processor, the memory and the I / O interface are connected to each other through a bus 104 and are further connected to other components of the computing device.

[0296] ​​​In some embodiments, the one or more processors comprise a field programmable gate array.

[0297] Embodiments of the present application also provide a computer readable storage medium. The computer readable storage medium stores a computer program, wherein the program, when executed by a processor, implements the steps in any of the heave compensation methods described above. The computer readable storage medium can be a volatile or non-volatile computer readable storage medium.

[0298] Embodiments of the present application also provide a computer program product comprising computer readable code, or a non-volatile computer readable storage medium carrying computer readable code, when the computer readable code is run in a processor of an electronic device, the processor in the electronic device performs the heave compensation method described above.

[0299] Example embodiments have been disclosed herein and, although the use of specific terms is expressly used herein, they are intended in the sense only of general descriptive purpose and should not be taken as limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics or elements described in connection with a particular embodiment can be used in conjunction with other embodiments unless expressly stated otherwise. As such, the skilled person will understand that various changes in form and detail can be made without departing from the scope of the present application as set forth in the appended claims.

Claims

1. A heave compensation method, characterized by, The method comprises the following steps: Obtaining a ship body heave signal measured by a heave measuring unit, and obtaining a prediction signal of ship body motion according to the ship body heave signal; Converting the prediction signal of ship body motion into displacement to obtain a vertical integrated heave displacement of a cable extension point; Generating a feedforward compensation amount according to the vertical integrated heave displacement, specifically including: inputting the vertical integrated heave displacement into a feedforward controller to obtain the feedforward compensation amount; The transfer function of the feedforward controller is: ； wherein, is the motor torque constant, is the moment coefficient, is the motor electrical constant, is the winch radius, is the reduction ratio; Obtaining a tracking error by subtracting a load displacement fed back by a feedback control chain from an instruction displacement; Obtaining a basic control amount according to the tracking error; Superimposing the feedforward compensation amount and the basic control amount to obtain a total control amount, and outputting the total control amount to a winch to drive the winch to wind or unwind the cable; After obtaining the total control amount, the method further comprises the following steps: subtracting the total control amount from a speed feedback signal to obtain an error signal, generating a motor control signal according to the error signal, and adjusting the motor speed / torque of the winch; Generating the motor control signal according to the error signal, specifically including: inputting the error signal into a speed controller to obtain the motor control signal; The transfer function of the speed controller is: ； wherein, is the motor torque constant, is the moment coefficient, is the motor electrical constant.

2. The method of claim 1, wherein: Obtaining a ship body heave signal measured by a heave measuring unit, and obtaining a prediction signal of ship body motion according to the ship body heave signal, including: Obtaining historical vertical displacement compensation amounts at a plurality of recent time points; Obtaining a polynomial describing heave motion according to the historical vertical displacement compensation amounts at the plurality of recent time points; Obtaining a prediction signal of ship body motion at a future time point through the polynomial.

3. The method of claim 2, wherein: The polynomial expression Y(j) is: a+b*(2+0.1*j)+c*(2+0.1*j)*(2+0.1*j)+d*(2+0.1*j)*(2+0.1*j)*(2+0.1*j), wherein, a=0.167*(3*x0+4*x1-x2); b=0.167*(y2-y1); c=0.056*(5*x2-3*x0-2*x1); d=0.167*(8*y1-y2); x0=data3; x1=0.5*(data4+data2); y1=0.5*(data4-data2); x2=0.5*(data5+data1); y2=0.5*(data5+data1); data1, data2, data3, data4, data5, and data6 are historical vertical displacement compensation amounts at the last six time points, and j defines a discrete time point in the future.

4. The method of claim 1, wherein: Obtaining a prediction signal of ship body motion according to a ship body heave signal, specifically including: superimposing the ship body heave signal and an inertial navigation measurement error to obtain a first superimposed signal, and obtaining the prediction signal of ship body motion according to the first superimposed signal, wherein the inertial navigation measurement error includes a measurement element error and a lever arm error.

5. The method of claim 1, wherein: The displacement conversion of the predicted signal of the ship motion specifically comprises: superimposing the predicted signal of the ship motion and a wave prediction error to obtain a second superimposed signal, and performing displacement conversion on the second superimposed signal to obtain a vertical comprehensive heave displacement, wherein the wave prediction error comprises a roll error, a pitch error and a heave error.

6. A heave compensation device, characterized by Comprise: The main control chain, the feedforward compensation chain, the feedback control chain, the feedforward compensation chain comprises a feedforward prediction module, a comprehensive heave displacement conversion module and a feedforward controller arranged in sequence, the feedforward prediction module is used for receiving the ship heave signal measured by the heave measuring unit in real time, and obtaining the predicted signal of the ship motion according to the ship heave signal, the comprehensive heave displacement conversion module is used for performing displacement conversion on the predicted signal of the ship motion to obtain the vertical comprehensive heave displacement of the cable extension point, and the feedforward controller is used for generating a feedforward compensation amount according to the vertical comprehensive heave displacement, and superimposing the feedforward compensation amount on the main control chain; the transfer function of the feedforward controller is: ； wherein, is the motor torque constant, is the moment coefficient, is the motor electrical constant, is the winch radius, is the reduction ratio; The main control chain comprises a first comparison module, a trajectory tracking controller, a main superposition module and an actuator arranged in sequence, the first comparison module is used for subtracting the load displacement fed back by the feedback control chain from the instruction displacement to obtain a tracking error, the trajectory tracking controller is used for obtaining a basic control amount according to the tracking error, and the main superposition module is used for superimposing and operating the feedforward compensation amount output by the feedforward controller and the basic control amount to obtain a total control amount, and outputting the total control amount to the winch to drive the winch to wind and unwind the cable; After obtaining the total control amount, the following steps are further included: subtracting the total control amount from the speed feedback signal to obtain an error signal, generating a motor control signal according to the error signal, and adjusting the motor speed / torque of the winch; The motor control signal is generated according to the error signal, specifically comprising: inputting the error signal into a speed controller to obtain the motor control signal; The transfer function of the speed controller is: ； wherein, is the motor torque constant, is the moment coefficient, is the motor electrical constant.

7. An electronic device, comprising: Comprise: One or more processors; Memory for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method of any one of claims 1 to 5.

8. A heave compensation system for a ship crane, characterized in that Comprise: The heave measuring unit is used for measuring the ship heave signal and transmitting the ship heave signal to the controller; The crane is used to realize the winding and unwinding of the cable, and complete the lifting of the load, and the crane is electrically connected with the controller; The controller is used to implement the method of any one of claims 1 to 5.

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