A marine intelligent testing device

Abstract

This invention provides a marine intelligent testing device, comprising: a heave measurement unit, a tension detection device, a winch, a telescopic mechanism, and a control unit. The heave measurement unit measures the heave signal of the ship and transmits the signal to the control unit. The winch is used to reel in and unelevate the cable. The telescopic mechanism includes a pulley system for guiding the cable, which is mounted on a telescopic beam. The telescopic beam is connected to a telescopic drive device for driving its horizontal movement. The winch cable passes through the pulley system on the telescopic mechanism and is connected to the test object. The tension detection device detects the tension on the cable and transmits the tension signal to the control unit. The control unit receives the heave signal and the tension signal, and based on these signals, outputs a first control signal to the winch to reel in and unelevate the cable, and outputs a second control signal to the telescopic drive device to extend or retract the telescopic beam.

Description

TECHNICAL FIELD

[0001] The present application relates to smart ocean intelligent equipment, in particular to a marine intelligent test device. BACKGROUND

[0002] In the development process of underwater detection equipment, in order to fully verify its performance, in addition to a large number of tests in inland waters such as lakes, various sea tests verification including wharf and real ship test are also needed. The underwater detection equipment adopts the shipborne flexible lifting method, which needs to be frequently retracted and released in actual use. If there is no intelligent retraction and release operation system, the test process will become very difficult and unsafe. On the other hand, when the underwater detection equipment is laid in the water for testing, its depth will change frequently due to the influence of sea waves and currents, and the performance of the equipment cannot be fully utilized. SUMMARY

[0003] The present application aims to solve at least one of the technical problems existing in the prior art, and proposes a marine intelligent test device.

[0004] The embodiment of the present application provides a marine intelligent test device, which comprises:

[0005] A heave measuring unit is used for measuring the heave signal of the ship body and transmitting the heave signal of the ship body to the control unit;

[0006] A winch is used for retracting and releasing the cable, and the winch is electrically connected with the control unit;

[0007] A telescopic mechanism comprises a pulley block used for guiding the cable, the pulley block is installed on a telescopic beam, the telescopic beam is connected with a telescopic driving device used for driving the horizontal movement of the telescopic beam, the cable of the winch passes through the pulley block on the telescopic mechanism and is connected with the test object, and the telescopic driving device is electrically connected with the control unit;

[0008] A tension detection device is used for detecting the tension on the cable and transmitting the tension signal to the control unit;

[0009] The control unit is used for receiving the heave signal and the tension signal, outputting a first control signal to the winch according to the heave signal and the tension signal to realize the retraction and release of the cable, and outputting a second control signal to the telescopic driving device to realize the expansion or retraction of the telescopic beam.

[0010] In some embodiments, the control unit is provided with a main control chain feedforward compensation chain, 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 by a heave measuring unit in real time, and obtain a ship body motion prediction signal according to the ship body heave signal, the comprehensive heave displacement conversion module being configured to convert the ship body motion prediction signal 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.

[0011] 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 a command 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.

[0012] In some embodiments, the feedforward compensation chain further comprises a data processing module, the data processing module being configured to perform smoothing interpolation processing on the ship body motion prediction signal, and output the ship body motion prediction signal to the comprehensive heave displacement conversion module.

[0013] In some embodiments, the feedforward compensation chain further comprises a first feedforward superimposition module, the first feedforward superimposition module being configured to superimpose the ship body heave signal and an inertial navigation measurement error to obtain a first superimposed signal, and transmit the first superimposed signal to the feedforward prediction module, the feedforward prediction module being configured to obtain the ship body motion prediction signal according to the first superimposed signal, and the inertial navigation measurement error comprising a measurement element error and a lever arm error.

[0014] In some embodiments, the feedforward compensation chain further comprises a second feedforward superimposition module, the second feedforward superimposition module being configured to superimpose the ship body motion prediction signal and a wave prediction error to obtain a second superimposed signal, and transmit the second superimposed signal to the comprehensive heave displacement conversion module, the comprehensive heave displacement conversion module being configured to convert the second superimposed signal into the comprehensive heave displacement, and the wave prediction error comprising a roll error, a pitch error and a heave error.

[0015] In some embodiments, the system further comprises a speed detection device, the speed detection device being configured to detect a rotating speed of a drum of the winch, and transmit a rotating speed signal to the control unit.

[0016] In some embodiments, a transfer function of the feedforward controller is:

[0017] ,

[0018] wherein, is a motor torque constant, is a moment coefficient, is a motor electrical constant, is a winch radius.

[0019] In some embodiments, the main control chain further comprises a second comparison module for differencing the total control quantity with a rotation speed feedback signal to obtain an error signal, and a rotation speed controller for generating a motor control signal according to the error signal to adjust the rotation speed / torque of the motor of the winch.

[0020] In some embodiments, the transfer function of the rotation speed controller is:

[0021] ,

[0022] wherein, is a motor torque constant, is a moment coefficient, is a motor electrical constant.

[0023] In some embodiments, the feedback control chain is configured to obtain a tension signal on the cable and a length of the cable from the point of extension to the load, and obtain the load displacement according to the tension signal, the vertical integrated heave displacement, and the length of the cable from the point of extension to the load.

[0024] In some embodiments, the feedback control chain comprises a state observer configured to obtain an estimated value of the length change of the cable according to the length of the cable from the point of extension to the load and the tension of the cable, and an operation module configured to sum the estimated value of the length change of the cable with the vertical integrated heave displacement, and to subtract the length of the cable from the point of extension to the load to obtain the load displacement, and feed back the load displacement to the comparison module.

[0025] In some embodiments, the feedforward prediction module is configured to obtain historical vertical displacement compensation quantities at a plurality of recent time points, and to obtain a polynomial describing the heave motion according to the historical vertical displacement compensation quantities at the plurality of recent time points, and to obtain a prediction signal of the ship body motion at a future time point through the polynomial.

[0026] 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),

[0027] wherein a = 0.167*(3*x0+4*x1-x2);

[0028] b = 0.167 * (y2 - y1);

[0029] c = 0.056 * (5 * x2 - 3 * x0 - 2 * x1);

[0030] d = 0.167 * (8 * y1 - y2);

[0031] x0 = data3;

[0032] x1 = 0.5 * (data4 + data2);

[0033] y1 = 0.5 * (data4 - data2);

[0034] x2 = 0.5 * (data5 + data1);

[0035] y2 = 0.5 * (data5 + data1);

[0036] data1, data2, data3, data4, data5, data6 are respectively the historical vertical displacement compensation amounts of the last 6 time points, and j defines a discrete time point in the future.

[0037] In some embodiments, the control unit is further configured to receive a deployment instruction, control the extension beam of the telescopic mechanism to be deployed, and synchronously control the winch to deploy the cable, so that the winch and the telescopic mechanism operate synchronously; after the extension beam is deployed to the position, the telescopic mechanism is controlled to stop operating, and after the test object reaches the preset depth, the winch is controlled to stop deploying the cable.

[0038] The control unit is further configured to receive a cable-retrieving instruction, control the winch to retrieve the cable, after the test object reaches the preset height, control the extension beam of the telescopic mechanism to be retracted, and synchronously control the winch to retrieve the cable, so that the winch and the telescopic mechanism operate synchronously, after the extension beam is retracted to the position, the telescopic mechanism is controlled to stop operating, and the winch is controlled to stop retrieving the cable.

[0039] In some embodiments, during the synchronous operation of the winch and the telescopic mechanism for deployment and retrieval, the movement speed Vj of the winch and the movement speed Vs of the telescopic mechanism satisfy the following relationship:

[0040] ,

[0041] simplified as a, simplified as b, that is ,

[0042] wherein M is the distance that the telescopic mechanism has operated, H is the vertical distance from the telescopic mechanism to the rotation center of the winch, and T is time.

[0043] The application has at least the following beneficial effects:

[0044] The ship intelligent test device has certain automatic deployment and recovery capabilities, can simulate the actual deployment and recovery process of the test object on the ship, and avoids the tediousness, insecurity and low efficiency of manual operation.

[0045] In order to ensure that the load does not come into contact with other objects during the extension and retraction of the telescopic beam of the telescopic mechanism, the winch is cooperatively controlled when the telescopic mechanism is telescoped.

[0046] On the other hand, the ship intelligent test device also has certain heave compensation capability, which can effectively offset the influence of sea waves on the depth of the towed test object.

[0047] The control unit 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 the heave and motion disturbance (such as the vertical / horizontal motion of the ship body caused by sea waves) in advance by synthesizing heave displacement filtering and B-spline interpolation, and actively offsets the effect before the disturbance affects the system. The state observer of the feedback control chain estimates the internal states such as cable length change and load displacement in real time, and provides accurate state feedback for the controller, solving the problem that the 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 test object accurately tracks the target trajectory.

[0048] 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 rapid response through feedforward compensation+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 ship heave and test object mutation. 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.

[0049] In summary, the control unit 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 rapid response ability to dynamic changes such as ship heave. The “double-path” design of feedforward and feedback reduces the influence of single-link failure on the overall control. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 A schematic diagram of a ship intelligent test device provided by the embodiments of the present disclosure;

[0051] Figure 2 A system block diagram of heave compensation control of an embodiment provided by the embodiments of the present disclosure;

[0052] Figure 3 Yet another system block diagram of heave compensation control provided for embodiments of the present disclosure;

[0053] Figure 4 Still another system block diagram of heave compensation control provided for embodiments of the present disclosure;

[0054] Figure 5 A whole flow chart of a prediction algorithm provided for embodiments of the present disclosure;

[0055] Figure 6 Another schematic diagram of a marine intelligent test device provided for embodiments of the present disclosure (including a fixed coordinate system and a motion coordinate system);

[0056] Figure 7 A workflow diagram of a simulation of a laying cabin provided for embodiments of the present disclosure;

[0057] Figure 8 A simulation of laying a cable provided for embodiments of the present disclosure;

[0058] Figure 9 An actual vertical comprehensive heave displacement curve diagram provided for embodiments of the present disclosure. DETAILED DESCRIPTION

[0059] 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 realize 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.

[0060] In the case of no conflict, each embodiment of the present application and each feature in the embodiments can be combined with each other.

[0061] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0062] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the 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.

[0063] 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.

[0064] Referring to Figure 1 The embodiment of the present application discloses a marine intelligent test device, comprising:

[0065] A heave measuring unit is configured to measure a heave signal of a ship body and transmit the heave signal of the ship body to a control unit;

[0066] A winch is configured to realize the winding and unwinding of a cable, and the winch is electrically connected to the control unit;

[0067] A telescopic mechanism comprises a sheave block configured to guide the cable, the sheave block is installed on a telescopic beam, the telescopic beam is connected to a telescopic driving device configured to drive the horizontal movement of the telescopic beam, the cable of the winch is connected to a test object through the sheave block on the telescopic mechanism, and the telescopic driving device is electrically connected to the control unit;

[0068] A tension detection device is configured to detect the tension on the cable and transmit a tension signal to the control unit;

[0069] The control unit is configured to receive the heave signal and the tension signal, output a first control signal to the winch according to the heave signal and the tension signal to realize the winding and unwinding of the cable, and output a second control signal to the telescopic driving device to realize the unfolding or retraction of the telescopic beam.

[0070] The marine intelligent test device can control the deployment and recovery of the test object (such as an underwater detection device), coordinate the operation of the winch and the telescopic mechanism during the deployment and recovery, and realize the heave simulation and heave compensation control of the test object.

[0071] In some embodiments, the winch is designed as a single-layer drum, the cable is wound around one layer when fully retracted, and the effective length of the winding drum is set as Therefore, it can be known that:

[0072] ,

[0073] In the formula, L is the cable length, d is the diameter of the cable groove, and D is the diameter of the cable drum. In the formula, L is the cable length, d is the diameter of the cable groove, and D is the diameter of the cable drum.

[0074] In some embodiments, the servo motor is provided with an encoder, which can be used for winch cable stroke measurement and collected by the control unit.

[0075] In some embodiments, the control unit is provided with a laying control module and / or a heave compensation control module, the laying control module is used for automatic laying and automatic recovery of the external test object, and the heave compensation control module is used for automatic heave compensation.

[0076] In some embodiments, the winch is further provided with a steering mechanism between the winch and the telescopic mechanism, the steering mechanism comprises a steering wheel, and the steering wheel is rotatably installed on a support.

[0077] The telescopic mechanism further comprises a mounting frame, and the telescopic beam is installed on the mounting frame and in sliding fit with the mounting frame.

[0078] The winch, the steering mechanism and the telescopic mechanism are all installed in the laying cabin. Figure 7 An analog laying cabin working flowchart is provided for the embodiments of the present application; see Figure 7 The general working flow of the analog laying cabin is as follows: first, the test equipment enters the cabin, the square cabin is hoisted and lifted to the test site, the square cabin is hoisted and laid to a suitable position such as the stern of the ship for carrying out the test, and the test is ready. Then, the cabin door is opened, the sonar wet end is laid to a predetermined depth through the laying control module, and the related test is carried out. In the test process, in order to ensure the test effect, the heave compensation control module is started, the heave, roll and pitch parameters of the system are measured according to the heave sensing unit fixed on the winch unit, the parameters are fed back to the control unit, the winch cable is adjusted through the control unit, and the sonar wet end is controlled within a certain depth error range. At the same time, the underwater attitude sensor monitors the sonar wet end and returns the attitude data for display. After the test is completed, the sonar wet end is recovered through the laying control module, the square cabin door and window are closed, the power is turned off, and the square cabin is removed.

[0079] In some embodiments, the laying control module is used for receiving the laying instruction of the user, controlling the telescopic beam of the telescopic mechanism to be unfolded, and synchronously controlling the winch to pay out the cable. After the telescopic beam is unfolded to the position, the telescopic mechanism is controlled to stop running, and after the test object reaches the preset depth, the winch is controlled to stop paying out the cable.

[0080] The deployment control module is used to receive the user's cable retrieval command, control the winch to retrieve the cable, and control the telescopic beam of the telescopic mechanism to retract after the test sample reaches the preset height. Simultaneously, it controls the winch to retrieve the cable. After the telescopic beam retracts into place, it controls the telescopic mechanism to stop operating and controls the winch to stop retrieval the cable.

[0081] In some embodiments, the marine intelligent testing device of the present invention further includes a command input device connected to the control unit. The command input device may be a switch and / or a touchscreen.

[0082] This invention allows for simulated deployment using a manual-electric control method. The mode selection switch is set to "manual" mode. The deployment process is as follows: First, manually open the electric gate and manually reel in the cable to lift the equipment to a safe height. Then, select high / low speed mode using the speed selection switch, and select the deployment mode using the operation selection switch. Control the telescopic beam of the telescopic mechanism to extend, and simultaneously control the winch to release the cable. Once the telescopic beam is fully extended, the telescopic mechanism stops operating, and the deployment / retrieval selection switch is set to the neutral position. The winch is then manually released to the preset depth. The cable release / retrieval selection switch is then set to the neutral position, the winch stops releasing the cable, and the simulated deployment process ends.

[0083] Recovery Process: First, manually select the cable retrieval mode. After the cable reaches a height suitable for retraction, select high / low speed mode via the speed selection switch, then select recovery mode via the operation selection switch. Control the retraction beam of the telescopic mechanism to retract, and simultaneously control the winch to retrieve the cable. Once the telescopic beam is retracted, the telescopic mechanism stops operating, and the deployment / retrieval selection switch is set to the neutral position. Manually release the cable from the winch, place the equipment on the bottom plate of the container, restore the initial state, set the deployment / retrieval selection switch to the neutral position, the winch stops releasing the cable, the electric door closes, and the simulated recovery process ends. The manual control panel also has an emergency stop button for emergency system shutdown in case of an emergency.

[0084] To ensure that the load does not come into contact with other objects during the extension and retraction of the telescopic boom, we implemented coordinated control of the winch during the extension and retraction of the telescopic mechanism. That is, the deployment control module of this invention needs to achieve coordinated control of the winch and the telescopic mechanism. The cable length L from the winch to the pulley and the linear displacement of the telescopic mechanism are considered. The vertical distance H between the telescopic mechanism and the winch rotation center exists as follows: Figure 8 The trigonometric function relationships are shown. Figure 8 In the diagram, M represents the distance the telescopic mechanism has traveled; P represents the distance the telescopic mechanism will travel in the next movement; L1 represents the distance from the cable to the pulley; L2 represents the distance from the cable to the pulley after the next movement of the telescopic mechanism; Vj represents the speed of the winch; and Vs represents the speed of the telescopic mechanism.

[0085] In some embodiments, during the process of synchronous operation of the winch and the telescopic mechanism for laying and recovering, the movement speed Vj of the winch and the movement speed Vs of the telescopic mechanism satisfy the following relationship:

[0086] ,

[0087] wherein M, H and T are all known constants, can be simplified as a, can be simplified as b, that is .

[0088] The relationship between the winch laying line speed and the time T, the telescopic mechanism speed can be obtained from the above, and the winch output speed is given according to the above operation result, which can ensure the synchronization of the winch laying line speed and the telescopic mechanism, and ensure the safety of the load.

[0089] In some embodiments, the cable is drawn out from the winch, extends to the external device through the tensioning wheel and the fixed pulley. The cable is laid and retracted through the motor and the speed reducer, and the compensation of the speed and position is realized through the real-time feedback of the IMU and the tension sensor.

[0090] The attitude measurement unit (IMU) is a kind of inertial measurement unit, which can measure the three degrees of freedom of the ship body in real time and give the current attitude speed. Through mathematical modeling of the compensation device, the change amount of the ship body heave degree of freedom corresponding to the change of each degree of freedom attitude can be calculated, which is applied to the winch device in real time, so as to offset the height change caused by the ship body movement and achieve the effect of heave compensation.

[0091] The tension sensor has two purposes, one is to keep the tension at a certain constant value during control, and the other is to control the constant tension during cable recovery. The function of the tension detection device is to detect the tension change on the cable, and the tension sensor is an important element of the device. The tension sensor detects the tension on the cable in real time, converts the tension change into an electrical signal, and the sensor sends the electrical signal to the control unit.

[0092] The function of the servo motor is to drive the winch to place the device at the required depth of the seabed, and to receive the control signal of the control unit and drive the winch to realize the laying and recovery of the cable, so as to achieve the function of wave compensation.

[0093] The winch body is mainly composed of a servo motor, a drum, a speed reducer and the like. The servo motor drives the drum to realize the safe laying and recovery of the cable. The full load state of the servo motor is the state of recovering the device, and the load of the servo motor is smaller under the wave compensation.

[0094] The front end of the telescopic mechanism is designed with a limit sensor for wet end cable recovery anti-collision limit to prevent the load from colliding with and damaging the upper end fixed pulley.

[0095] In some embodiments, the intelligent test device for ship of the present application further comprises a speed detection device configured to detect the rotating speed of the drum of the winch body, and then send an electric signal to the control unit, which judges the position and speed of the equipment in the wave according to the electric signal, and decides whether to switch the working condition and carry out the winding and unwinding of the cable.

[0096] The heave compensation of the present application adopts an active compound compensation mode, and the compensation driving mode is selected as an electric control driving mode considering that the load of the compensation object is small (60-200 kg). The corresponding control software is formed through heave compensation dynamics modeling and control algorithm, and a high residual compensation precision is realized by the heave compensation winch, which can well offset the influence of the sea wave heave on the stability of the wet end of the sonar, and effectively guarantee the verification of various detection performance indexes and use performance indexes of the sonar.

[0097] The ship will produce six degrees of freedom motion, i.e. sway, surge, heave, roll, pitch and yaw, under the action of sea waves, and various operation systems and auxiliary systems on the ship body will also produce heave motion, which will produce high load influence on the ship operation and also cause great operation loss and safety hidden danger. For underwater hoisting, the cable length and water resistance are generally large, and the swing situation does not generally occur. However, the ship motion caused by sea waves will cause the dramatic change of the cable tension, and the influence of ship heave on the cable tension is the most significant. When the tension change exceeds the design limit, the cable may be broken. Therefore, in order to guarantee the safety of the sea operation, certain technical means must be adopted to compensate the influence of the ship motion.

[0098] The ship sailing in the wind and wave will produce six degrees of freedom motion, i.e. pitch, roll, yaw, sway, surge and heave (heave), and in combination with the actual use condition of the test equipment, the heave compensation system needs to compensate the cable length, and the cable length can be decomposed into vertical and horizontal directions. For the vertical direction of the ship stern, the most influential motions are the pitch and heave motions, and for the horizontal direction of the ship stern, the most influential motions are the yaw and sway motions. The present scheme adopts the inertial navigation to measure the total heave and sway motions of the ship stern, wherein the heave motion is the vertical component superposition of the pitch and heave motions, and the sway motion is the horizontal component superposition of the yaw and sway motions.

[0099] The present scheme adopts the rotary heave compensation device in the form of winch, establishes the complete mathematical model of the heave compensation system, introduces the multi-closed loop thought in the electric drive system into the heave compensation control system, constructs the control structure containing three closed loops, analyzes the dynamic characteristics from the frequency domain, and gives the design method of the three controllers. In order to obtain accurate depth setting precision, the present application also constructs the state observer based on the cable tension detection, and fully considers the feasibility of physical implementation.

[0100] The active heave compensation system is a winch heave compensation system. The equipment at the bow and stern of the ship is kept at the same depth on the sea floor by the motor winch. In view of the feasibility of practical application, the design is constructed by using a motion reference unit to measure the heave motion of the ship body in real time. The heave displacement of the ship body is taken as a measurable disturbance. The feedforward compensator is designed by using the structure invariance principle to improve the compensation accuracy of the system.

[0101] The heave signal of the ship can be collected by the inertial navigation sensor arranged near the winch to obtain the attitude change of the ship. The attitude change in the heave direction, the attitude change speed and acceleration are further calculated by coordinate transformation. The output signal of the acceleration sensor is disturbed by the zero drift, zero offset, high frequency noise and the like.

[0102] The tension sensor is used to detect the dynamic tension of the cable in real time. When the ship heaves, the equipment placed in the water will change the tension of the cable. The tension sensor detects the force of the cable during traction and feeds back the signal to the control system.

[0103] The control unit is used to collect the heave motion acceleration signal and the tension signal of the ship, and to perform mathematical processing such as smoothing, filtering and integration on the collected signals to obtain the speed and displacement of the heave motion of the ship and other related information. The control amount of the electric winch is calculated by using the PID control algorithm.

[0104] In some embodiments, referring to Figures 2 to 4 , the heave compensation control module includes a main control chain, a feedforward compensation chain and a feedback control chain. The feedforward compensation chain includes a feedforward prediction module, a comprehensive heave displacement conversion module and a feedforward controller arranged in sequence. The feedforward prediction module is used to receive the heave signal measured by the heave measurement unit in real time, and obtain a prediction signal of the ship motion (a prediction signal of the ship motion in the next control period) according to the heave signal. The comprehensive heave displacement conversion module is used to convert the prediction signal of the ship motion to obtain the vertical comprehensive heave displacement of the cable extension point M (such as the top end of the crane). The feedforward controller is used to generate a feedforward compensation amount according to the vertical comprehensive heave displacement, and superimpose the feedforward compensation amount on the main control chain.

[0105] The main control chain includes a first comparison module, a trajectory tracking controller, a main superposition module and an actuator arranged in sequence. The first comparison module is used to subtract the instruction displacement from the load displacement feedback by the feedback control chain to obtain a tracking error. The trajectory tracking controller is used to obtain a basic control amount according to the tracking error. The main superposition module is used 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 reel in or out the cable.

[0106] Since the active heave compensation control unit is a position disturbance system, simple closed-loop control is difficult to achieve good control effect. Therefore, according to the principle of structural invariance, the system designs a feedforward controller to suppress the ship motion disturbance. The ship motion signal measured by the inertial navigation attitude sensor is input to the AR prediction model after low-pass filtering, and the future motion trend of the ship body is obtained. Through the feedforward controller, it is superimposed into the closed-loop control loop and output to the control unit to control the servo motor, so that the servo motor can wind the cable in advance to eliminate other attitude disturbances.

[0107] In some embodiments, the feedforward prediction module is configured to obtain historical vertical displacement compensation amounts at a plurality of time points in the past, i.e., historical heave compensation calculation results, obtain a polynomial describing heave motion according to the historical vertical displacement compensation amounts at the plurality of time points in the past, and obtain a prediction signal of ship body motion at a future time point through the polynomial.

[0108] 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),

[0109] wherein a=0.167*(3*x0+4*x1-x2);

[0110] b=0.167*(y2-y1);

[0111] c=0.056*(5*x2-3*x0-2*x1);

[0112] d=0.167*(8*y1-y2);

[0113] x0=data3;

[0114] x1=0.5*(data4+data2);

[0115] y1=0.5*(data4-data2);

[0116] x2=0.5*(data5+data1);

[0117] y2=0.5*(data5+data1);

[0118] data1, data2, data3, data4, data5, data6 are historical vertical displacement compensation amounts at the last 6 time points, i.e., historical heave compensation calculation results, and j defines a discrete time point in the future.

[0119] The heave compensation predicted displacement amount slash_cha=cha_value[j] at a future time (determined by j);

[0120] The predicted velocity slash_vol=b+4*c+12*d;

[0121] The predicted acceleration slash_acc=2*c+12*d.

[0122] The heave compensation predicted displacement amount slash_cha=cha_value[j] at a future time (determined by j);

[0123] The heave compensation predicted displacement amount slash_cha=cha_value[j] at a future time (determined by j); The rotation angle The translation distance The rotation angle The translation distance The rotation angle The translation distance The rotation angle The translation distance The heave compensation predicted displacement amount slash_cha=cha_value[j] at a future time (determined by j);

[0124] The heave compensation predicted displacement amount slash_cha=cha_value[j] at a future time (determined by j);

[0125] The heave compensation predicted displacement amount slash_cha=cha_value[j] at a future time (determined by j);

[0126] 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])).

[0127] 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])).

[0128] Fixed system and motion system vertical difference delta_l = Wheel_Point_f[2] - Wheel_Point_m[2].

[0129] Heave displacement heave_convert = A * delta_l. A is the proportional coefficient of the actual heave physical quantity. In some embodiments, A is 3.6.

[0130] The present application also includes: batch storage of N (such as 6) historical vertical displacement compensation quantities, and automatic switching to the "calculation state" after storage, that is, obtaining a polynomial describing the heave motion according to the historical vertical displacement compensation quantities at the last N (such as 6) time points;

[0131] The prediction signal of the ship body motion at the future time point is obtained through the polynomial.

[0132] The historical vertical displacement compensation quantities at multiple time points are sequentially stored in the array present_data, specifically:

[0133] When the system is in the "data saving state", the following operations are performed:

[0134] The currently input historical vertical displacement compensation quantity slash is stored in the i-th position (i is the array index, starting from 0) of the array present_data.

[0135] The index i is incremented by 1, in preparation for storing the next slash value.

[0136] It is determined whether 6 pieces of data have been stored:

[0137] If i < 6 (not full), the "data storage state" is maintained, and the next slash value is received and stored. If i ≥ 6 (full), the state is switched to the "calculation state", that is, a polynomial describing the heave motion is obtained according to the historical vertical displacement compensation amounts at the last N (e.g., 6) time points.

[0138] The flag slash_flag is used to mark that the data has been stored, for other logic (e.g., the calculation module) to determine whether to start processing.

[0139] The above method of the application realizes "sliding window type data acquisition", and through the i counting, it is ensured that the present_data array always stores "the slash data at the last 6 time points" (from present_data[0] to present_data[5]); after the storage is full, the state switching is automatically triggered, the "data calculation" process is connected, which is a key link of the "acquisition-processing" closed loop, and it ensures that the subsequent calculation has enough historical data support (e.g., the 6 data are used to fit a polynomial in the code).

[0140] The application also controls the number of "future motion prediction" through the counting variable j, and updates the historical data array after the prediction is completed, to form a closed loop of "calculation-update-re-calculation". The specific analysis is as follows:

[0141] J is an "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.

[0142] When j < M (not complete M time point prediction): j is incremented by 1, the state.calculate state is maintained, and the prediction value (cha_value[j]) of the next future time point is continuously calculated.

[0143] When j ≥ M (M time point prediction has been completed): theoretically, the state is switched to state.update (update data).

[0144] In some embodiments, M is 10.

[0145] Regardless of whether j is less than M (e.g., M is 10), eventually, the state.update state is entered (redundant logic in the code design to "ensure that the data is updated in time", to avoid state being stuck due to j counting abnormality).

[0146] state.update state (update data) includes: update the historical data array, prepare for the next round of prediction.

[0147] Array left shift: through the loop of k=1~4, update the elements of index 1~4 in present_data 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], which is no longer used in subsequent calculations).

[0148] 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 historical data".

[0149] Reset the count and state: j is reset to 1 (start from the beginning to calculate 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.

[0150] The above process of the application is: using the current 6 historical data to calculate the prediction value of 10 future time points → discarding the oldest data, supplementing new data, resetting the count → returning to state.calculate, i.e. continuing to predict the next batch of 10 future time points based on the updated 6 historical data.

[0151] The above scheme of the application realizes continuous and real-time prediction of ship motion through "rolling update of historical data + repeated prediction of future time points". J controls the calculation of the prediction value of 10 future time points each time, and after completion, it is forced to enter the data update state. State.update maintains the latest 6 historical data through "array left shift + new data supplement", 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", which guarantees the continuity and timeliness of the motion prediction.

[0152] In some embodiments, the feedforward compensation chain further includes a data processing module for performing smoothing interpolation processing on the predicted signal of ship motion and outputting to the comprehensive heave displacement conversion module.

[0153] In some embodiments, the feedforward compensation chain further includes a first feedforward superposition module for superimposing the ship body heave signal and the inertial navigation measurement error to obtain a first superposition signal, and transmitting the first superposition signal to the feedforward prediction module, the feedforward prediction module is used to obtain the predicted signal of ship motion according to the first superposition signal, and the inertial navigation measurement error includes measurement element error and lever arm error.

[0154] In some embodiments, the feedforward compensation chain further comprises a second feedforward superposition module, configured to superimpose a predicted signal of the hull motion and a wave prediction error to obtain a second superposition signal, and transmit the second superposition signal to a comprehensive heave displacement conversion module, which is configured to convert the second superposition signal into a comprehensive heave displacement.

[0155] In some embodiments, the intelligent marine test device further comprises a speed detection device, which is configured to detect the rotating speed of the drum of the winch body, and then transmit an electric signal to the control unit, so that the control unit determines the position and speed of the device in the wave and decides whether to switch the working condition and release or wind the cable.

[0156] In some embodiments, the main control chain further comprises a second comparison module and a rotating speed controller, 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.

[0157] The rotating speed feedback signal is the rotating speed detected by the speed detection device.

[0158] In some embodiments, the feedback control chain is configured to obtain a tension signal on the cable and a length of the cable from the extension point to the test object (or a release length of the cable), and obtain a load displacement according to the tension signal, the vertical comprehensive heave displacement and the length of the cable from the extension point to the test object (or the release length of the cable).

[0159] In some embodiments, the feedback control chain comprises a state observer and a calculation module, the state observer is configured to obtain an 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 F of the cable , the calculation 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 from the extension point to the load to obtain an estimated load displacement (an estimated value of the load displacement), and feed back the estimated load displacement to the comparison module.

[0160] In other embodiments, the feedback control chain can also be free of state observers, but instead the load displacement is acquired by motor encoders or encoders at the pulley. That is, the present application can also detect the angle of rotation of the motor through the motor encoder, real-time calculate the length of the cable winding and unwinding and the load displacement, or detect the angle of rotation of the pulley through the encoder, real-time calculate the length of the cable winding and unwinding and the load displacement.

[0161] In other embodiments, the feedforward prediction module adopts a prediction algorithm based on an AR model. The principle of the AR prediction model is to read historical ship motion data, obtain the approximate curve of the signals through fitting, and finally predict the ship in the future for a certain time through the curve obtained by fitting.

[0162] In order to weaken the disturbance caused by the displacement of the ship body, the present application adopts attitude displacement compensation and ship body speed compensation to weaken the influence on the heave. Since the original signal of the inertial navigation will have a certain delay, and the sampling rate is low, the present application designs a polynomial feedforward prediction algorithm based on time series, which can derive the motion trend of the current or even future ship body according to the historical wave signal, and through the feedforward controller, the system can take action in advance to offset the adverse effects caused by time lag and large inertia characteristics.

[0163] The present application can also detect the angle of rotation of the pulley through the encoder, and real-time calculate the length of the cable winding and unwinding.

[0164] In some embodiments, before the displacement conversion of the predicted signal of the ship body motion, the following step is further included: performing a smooth interpolation processing on the predicted signal of the ship body motion.

[0165] In some embodiments, the predicted signal of the ship body motion is obtained according to the ship heave signal, and specifically includes: inputting the ship heave signal into an AR prediction model to obtain the predicted signal of the ship body motion.

[0166] In a relatively short time range, the vertical motion of the test object caused by the ship motion can be regarded as a stationary random process, and the vertical displacement thereof obeys the following AR prediction model:

[0167] ,

[0168] Wherein: - the order of the AR model;

[0169] - the autoregressive coefficient of the AR model;

[0170] - the white noise sequence.

[0171] The key to obtaining an AR prediction model with high accuracy is to estimate the autoregressive coefficient of the model Here we use the least square method to estimate the vector of autoregressive coefficients from historical data , and the estimated vector is .

[0172] After the estimation of autoregressive coefficients , we need to find 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.

[0173] The system selects the AIC criterion order determination method. First, we determine the maximum order of the model by offline estimation. Then we take the order from 1 to , and bring each order into the AR model to estimate the autoregressive coefficients in the model by the least square method, and calculate the AIC criterion number of each model. Finally, we compare the size of all , and when there is a that makes , it is the order of the AR prediction model.

[0174] After getting the autoregressive coefficients and the order of the AR model from historical data, the predicted wave data in the future steps is:

[0175] When , we have:

[0176] When , we have:

[0177] When , we have:

[0178] The overall flow chart of the wave prediction algorithm is shown in Figure 5 .

[0179] Because of the roll and pitch of the ship, the heave displacement of each point on the ship is not the same. The inertial measurement unit used to measure the change of the ship's 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.

[0180] ​In the system, the real-time attitude of the ship motion is read by inertial navigation to obtain the real-time data of wave disturbance. The wave disturbance is applied to 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 in the vertical direction to the cable contraction point by conversion.

[0181] The system needs to determine the mathematical relationship between the cable length and the ship attitude by measuring the motion law of the inertial navigation data. Considering the convenience of calculation, two coordinate systems are established as shown in Figure 6

[0182] 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, which is simply referred to as the body coordinate system or the dynamic coordinate system. The fixed coordinate system O is relatively static with respect to the earth, which is simply referred to as the static coordinate system or the fixed coordinate system. When the initial position is set, the dynamic coordinate system coincides with the static coordinate system.

[0183] Assume that the inertial measurement unit measures the rotation angle of the ship body around as , the translation distance as , the rotation angle around as , and the translation distance as , the rotation angle around as , and the translation distance as . The motion attitude of the ship body at this time is obtained, and the coordinate system P is established with the position of the inertial measurement unit after motion as the origin. The rotation transformation matrix from the coordinate system P to the coordinate system P is:

[0184] .

[0185] For convenience of writing, is the abbreviation of , and is the abbreviation of .

[0186] The translation transformation vector from the coordinate system P to the coordinate system P is:

[0187]

[0188] Let point M be the position of the cable contraction point, the coordinates of M in the coordinate system P are , and the ship body can be regarded as a rigid structure. When point moves to point , when point moves to point , and at this time point ​​​​​In coordinate system The coordinates in are .

[0189] Then point The coordinates in coordinate system P (or static coordinate system) are:

[0190]

[0191] Let the obtained coordinates be Then, the combined vertical heave displacement caused by the ship's motion at the cable retraction point is:

[0192]

[0193] When at rest, the origin can be obtained in coordinate system P, and the coordinates of point P are: The coordinates of point M are The unit is meters.

[0194] Assume the ship moves to the coordinate system In the middle of the time, there was for , for Because the relative position of point M to the hull remains unchanged, M in the coordinate system... The coordinates are .

[0195] It can be calculated at this time In coordinate system The coordinates in are Then point The coordinates in coordinate system P are:

[0196]

[0197] The obtained coordinates are . 1.82. If the heave of the inertial navigation system installation point is used instead of the heave of the rope exit point, then:

[0198] .

[0199] 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 based on the error signal, and adjusting the motor speed / torque of the winch.

[0200] In some embodiments, generating a motor control signal based on an error signal specifically includes: inputting the error signal into a speed controller to obtain a motor control signal.

[0201] Speed controller design: From the system model, the open-loop transfer function of the speed loop of the servo motor is:

[0202]

[0203] 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 its transfer function is:

[0204]

[0205] In order to let the controller zero point and the large time constant pole of the controlled object cancel out, The control parameters satisfy the condition:

[0206] ,

[0207] Take , .

[0208] The speed loop .

[0209] In some embodiments, according to the tracking error, the basic control quantity is obtained, specifically including: inputting the tracking error into a trajectory tracking controller to obtain a basic control quantity.

[0210] Trajectory tracking controller design: The open-loop transfer function of the load displacement outer loop is further derived:

[0211]

[0212] Ignoring the effect of cable damping C, the frequency characteristics of the above formula The frequency characteristics of

[0213] .

[0214] The frequency characteristics of

[0215]

[0216] The approximate conditions for simplifying the above outer loop are: the cutoff frequency And .

[0217] Therefore, the open-loop transfer function of the simplified position outer loop is:

[0218] .

[0219] This system can use proportional control, and the proportional coefficient can be taken as .

[0220] In some embodiments, the feedforward compensation quantity is generated according to the vertical comprehensive heave displacement, specifically comprising: inputting the vertical comprehensive heave displacement into a feedforward controller to obtain the feedforward compensation quantity.

[0221] 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:

[0222]

[0223] 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, and the simplified feedforward controller can be obtained as follows:

[0224] ,

[0225] wherein, is a motor torque constant, is a motor electrical constant, is the total inertia of the winch, reducer, etc. converted to the motor output shaft, is the total viscous damping coefficient of the winch, reducer, etc. converted to the motor output shaft, is the winch radius, is the reduction ratio, is the cable damping coefficient, is the cable stiffness coefficient, is the equivalent static tension, is the equivalent mass, is the mechanical efficiency.

[0226] The residual error of the control unit 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 .

[0227] In some embodiments, the prediction signal of the ship body motion is obtained according to the ship body heave signal, specifically comprising: superimposing the ship body heave signal and the inertial navigation measurement error to obtain a first superimposed signal, and obtaining the prediction signal of the ship body motion according to the first superimposed signal. In some embodiments, the prediction signal of the ship body motion is displacement converted, specifically comprising: superimposing the prediction signal of the ship body motion and the wave prediction error to obtain a second superimposed signal, and displacement converting the second superimposed signal to obtain the comprehensive heave displacement.

[0228] wherein the inertial navigation measurement error and wave prediction error including roll error, pitch error and heave error. is the simplified feedforward controller. is the total coulomb friction torque converted to the motor output shaft.

[0229] the inertial navigation measurement error and wave prediction error after superposition and input into the integrated heave displacement conversion equation are:

[0230] ,

[0231] wherein is the heave displacement conversion equation, is the ship pose quantity in ideal state, is the vertical integrated heave displacement of the cable extension point in actual state.

[0232] Further, the vertical integrated heave displacement of the cable extension point in actual state is input into the simplified feedforward controller , the error acting on the load displacement is:

[0233] ,

[0234] wherein is the vertical integrated heave displacement of the cable extension point in ideal state; is the common fraction of the two transfer functions; is the rotational speed loop transfer function.

[0235] According to the system model, the error of the mechanism friction acting on the load displacement is:

[0236]

[0237] Since the error caused by the mechanism friction is independent of other error sources, the total system error is:

[0238]

[0239] 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 5cm or 5%.

[0240] The cause of the lever arm error: when the mass center of the inertial navigation system 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.

[0241] According to the data, due to the Lever arm effect, the specific force at the position of the inertial navigation system and the specific force at the mass center of the ship have the following relationship:

[0242] ,

[0243] is the specific force at the position of the inertial navigation system, is the specific force at the mass center of the ship, is the length of the lever arm, is the angular velocity of the ship relative to the inertial coordinate system.

[0244] The error term is .

[0245] Next, the parameters of and are determined. It can be approximately considered that the mass center of the ship is at the geometric center of the ship. The inertial navigation system is located on the stern deck, and a rectangular coordinate system is established with the mass center of the ship as the origin, which can obtain .

[0246] According to the data, the roll amplitude of a large ship under extreme conditions is 30°, and the roll period is , where C is the roll period coefficient and can be taken as 0.8, B is the ship width and can be taken as 14.28m, is the initial stability height and can be taken as 0.8m, and is obtained. The roll motion is approximated as a sinusoidal motion, and the roll angle .

[0247] The pitch amplitude of a large ship under extreme conditions is 20°, and the pitch period is , where is the pitch period coefficient and can be taken as 0.55, L is the ship length and can be taken as 100m, and is obtained. The pitch motion is approximated as a sinusoidal motion, and the roll angle .

[0248] The derivatives of the roll and pitch angles are calculated as follows: , .

[0249] Substituting the above values, the following can be calculated: .

[0250] The displacement error caused by this is .

[0251] ​​So the inertial navigation measurement error vector is:

[0252] .

[0253] In this system, the inertial navigation signal has a certain delay, and the sampling rate is low. We designed a polynomial feedforward prediction algorithm based on time series, which can infer the current and even future ship motion trend according to the historical signal, and compensate to the control loop according to the system delay, to offset the adverse effects of time delay and large inertia on the system control.

[0254] When multi-step prediction is performed, the prediction data after the previous prediction is obtained, so it is easy to cause error accumulation when long-term prediction is performed.

[0255] When the historical data sequence obeys the known prediction model, the prediction value of the future step ( ) heave displacement is:

[0256] (1) when ,

[0257] ;

[0258] (2) when ,

[0259] ;

[0260] Where p is the set order.

[0261] In this system, the sampling period T of the inertial navigation is 0.01s, and the response time of the entire system is about according to the experience estimation, so two-step prediction is selected, and the prediction time is 0.02s. Using matlab for simulation analysis, taking the heave displacement signal as , the roll angle signal , and the pitch angle signal , the three signals are predicted respectively, and the maximum heave displacement error is 0.0125m, the maximum roll angle error is , and the maximum pitch angle error is .

[0262] As can be seen from the above, the wave prediction error includes roll error, pitch error and heave error, so the wave prediction error vector is:​

[0263]

[0264] From the foregoing error propagation analysis, the inertial navigation measurement error and the wave prediction error are superimposed and input into the integrated heave displacement conversion equation to obtain the vertical integrated heave displacement of the cable extension point in the actual state . which is then input into the simplified feedforward controller and finally acts on the load displacement .

[0265] Therefore, the vertical integrated heave displacement of the cable extension point in the actual state needs to be solved first. Let the ship's pose in the ideal state be , and the heave motion amplitude be 1.5 m. Due to the influence of the inertial navigation measurement error and the wave prediction error , the actual measured pose of the ship is:

[0266]

[0267] From the coordinate transformation, in the ideal state, the cable retraction point moves to , and its coordinates in the static coordinate system P are:

[0268]

[0269] At this time, the integrated vertical heave displacement of the cable retraction point caused by the ship's motion is:

[0270]

[0271] However, in the actual situation, due to the existence of errors, its coordinates in the static coordinate system P are:

[0272]

[0273] The actual heave displacement obtained is:

[0274] and the vertical integrated heave displacement of the cable extension point in the actual state is obtained as shown in Figure 9 .

[0275] Further, the vertical integrated heave displacement of the cable extension point in the actual state is input into the simplified feedforward controller , and the load displacement The error is:

[0276] ,

[0277] Wherein The maximum error is .

[0278] The above is the error of the wave signal with a heave variation amplitude of 1.5 meters to the system, and the error of different wave signals to the system is related to the heave variation amplitude, which will be analyzed below. The ideal state of the ship is , and the heave motion amplitude is A.

[0279] In the ideal state, the cable contraction point moves to , The coordinates in the static coordinate system P are:

[0280]

[0281] In the actual situation, The coordinates in the static coordinate system P are:

[0282] .

[0283] Obviously, there is not a simple proportional relationship between the amplitude and the residual error, and the invention uses matlab quadratic polynomial fitting to obtain , wherein represents the amplitude.

[0284] 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:

[0285] ,

[0286] Wherein, 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.

[0287] After analyzing the data, it can be obtained that , , .

[0288] According to the mathematical model, it can be obtained that the error of the friction of the mechanism acting on the load displacement is:

[0289]

[0290] rated speed of the power take-off i.e. error value for- m.

[0291] Through the above calculation and analysis, the total error of the system is:

[0292] When A=0.3m, the error is 0.047486m, which is less than 0.05m;

[0293] When A=0.5m, the error is 0.049486m, which is less than 0.05m;

[0294] When A=0.8m, the error is 0.065486m, and the residual error is 8.1%;

[0295] When A=1m, the error is 0.070486m, and the residual error is 7%;

[0296] When A=1.2m, the error is 0.076486m, and the residual error is 6.3%;

[0297] When A=1.5m, the error is 0.086m, and the residual error is 5.73%;

[0298] In summary, the residual error of the system meets the performance index requirements.

[0299] The control unit also collects the roll angle, pitch angle, azimuth angle, heave value, residual error and other data and feeds them back to the upper computer in real time.

[0300] The heave simulation is a sinusoidal heave signal actively generated by the system during testing, and is a working mode of the winch working state during reaction simulation heave compensation. The system software automatically generates a standard sinusoidal signal, the amplitude and frequency can be set, and the amplitude and frequency setting values are not greater than the maximum working capacity of the system.

[0301] The overall functional requirements of the marine intelligent test device of the application are:

[0302] 1. The heave compensation operation can be started, and the heave compensation operation is automatically performed according to the real-time change of heave;

[0303] 2. The cable tension signal can be collected, and when the tension exceeds the range, an alarm can be given and the winch can be controlled to stop urgently;

[0304] 3. The motor has a power-off brake function, which ensures that the test object does not continuously drop when the system suddenly loses power;

[0305] 4. The winch has a cable winding and unwinding limit;

[0306] 5. The extension and retraction of the telescopic mechanism can be controlled, the running speed is divided into high speed mode and low speed mode, and the telescopic mechanism limiting signal acquisition function is provided;

[0307] 6. It has the functions of emergency stop, automatic start / stop, etc.

[0308] Example embodiments have been disclosed herein and, although the use of specific terms is exemplified throughout, they are used in this context only and should not be construed as limiting in any manner. In some instances, it will be proximate to those skilled in the art that features, characteristics and / or elements described in connection with a particular embodiment can be used alone or in combination with other embodiments unless otherwise explicitly indicated. Therefore, those skilled in the art 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 marine intelligent test system, characterized in that, The utility model relates to a kind of ship motion control system, including: heave measuring unit, the heave measuring unit is used to measure ship body heave signal, and the heave signal of ship body is passed to control unit; winch, the winch is used to realize the take-up of cable, the winch is electrically connected with control unit; retractable mechanism, the retractable mechanism includes for the pulley block of cable guiding, the pulley block is installed on retractable beam, the retractable beam is connected with retractable drive device for driving retractable beam horizontal movement, the cable of winch passes through the pulley block on retractable mechanism and is connected with test object, the retractable drive device is electrically connected with control unit; tension detection device, the tension detection device is used to detect tension on cable, and passes tension signal to control unit; control unit, the control unit is used to receive the heave signal, tension signal, and according to the heave signal, tension signal, output first control signal to winch, realize the take-up of cable;Output second control signal to retractable drive device, realize the deployment or retraction of retractable beam; The control unit is provided with main control chain feedforward compensation chain, feedback control chain, the feedforward compensation chain includes the feedforward prediction module, integrated heave displacement conversion module and feedforward controller arranged in sequence, the feedforward prediction module is used to receive the heave signal of ship body that heave measuring unit real-time measurement, and according to ship body heave signal, obtain the forecast signal of ship body movement, the integrated heave displacement conversion module is used to carry out displacement conversion to the forecast signal of ship body movement, obtains the vertical integrated heave displacement of cable extension point, the feedforward controller is used to generate feedforward compensation according to the vertical integrated heave displacement, and the feedforward compensation is superimposed to main control chain; The main control chain includes the first comparison module, trajectory tracking controller, main superposition module and actuator arranged in sequence, the first comparison module is used to difference instruction displacement and the load displacement that feedback control chain feedback, obtains tracking error, the trajectory tracking controller is used to obtain basic control quantity according to the tracking error, the main superposition module is used to carry out superposition operation to the feedforward compensation of feedforward controller output and basic control quantity, obtains total control quantity, and is output to winch, drives winch to take-up cable.

2. The system of claim 1, wherein: The feedforward compensation chain further includes data processing module, and the data processing module is used for the forecast signal of ship body movement is carried out smooth interpolation processing, and is output to integrated heave displacement conversion module.

3. The system of claim 1, wherein: The feedforward compensation chain further includes first feedforward superposition module, the first feedforward superposition module is used to superimpose ship body heave signal and inertial navigation measurement error, obtains first superposition signal, and passes first superposition signal to feedforward prediction module, the feedforward prediction module is used to obtain the forecast signal of ship body movement according to first superposition signal, the inertial navigation measurement error includes measuring element error and lever arm error.

4. The system of claim 1, wherein: The feedforward compensation chain further comprises a second feedforward superposition module, configured to superimpose a predicted signal of the hull motion and a wave prediction error to obtain a second superposition signal, and transmit the second superposition signal to a comprehensive heave displacement conversion module, which is configured to convert the second superposition signal into a comprehensive heave displacement.

5. The system of claim 1, wherein: The main control chain further comprises a second comparison module and a rotating speed controller, 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.

6. The system of claim 1, wherein: The feedback control chain comprises a state observer and an operation module, the state observer is configured to obtain an estimated value of the length change of the cable according to the length of the cable from the cable extension point to the test object and the tension of the cable, and 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 from the cable extension point to the test object to obtain a load displacement, and feed back the load displacement to the comparison module.

7. The system of claim 1, wherein: The feedforward prediction module is configured to obtain historical vertical displacement compensation quantities at a plurality of recent time points, and obtain a polynomial describing heave motion according to the historical vertical displacement compensation quantities at the plurality of recent time points, and obtain a predicted signal of the hull motion at a future time point through the polynomial.

8. The system of claim 7, 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 quantities at the six most recent time points, and j defines a discrete time point in the future. The control unit is further configured to receive a deployment instruction, control the extension beam of the telescopic mechanism to be unfolded, and synchronously control the winch to deploy the cable, so that the winch and the telescopic mechanism operate synchronously to deploy; after the extension beam is unfolded to the position, the telescopic mechanism is controlled to stop operating, and after the test object reaches the preset depth, the winch is controlled to stop deploying the cable. The control unit is further configured to receive a cable recovery instruction, control the winch to recover the cable, after the test object reaches the preset height, control the extension beam of the telescopic mechanism to be retracted, and synchronously control the winch to recover the cable, so that the winch and the telescopic mechanism operate synchronously to recover, after the extension beam is retracted to the position, the telescopic mechanism is controlled to stop operating, and the winch is controlled to stop recovering the cable. ​ ​ ​ ​ ​ ​ ​ ​ ​ 9. The system of claim 1, wherein: ​ ​

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