阅读说明：本技术 一种伸缩式栈桥系统及其控制方法 (Telescopic trestle system and control method thereof ) 是由 蔡东伟 徐林 胡贯勇 孟旭 秦一飞 于 2019-11-07 设计创作，主要内容包括：本发明公开了一种伸缩式栈桥系统及其控制方法,安装于支持平台或支持船上,包括设于所述支持平台或支持船上的圆筒体,所述圆筒体上通过回转机构连有回转底盘,所述回转底盘上设有液压泵站和驾驶室,所述回转底盘上连有栈桥固定段,所述液压泵站通过变幅机构与所述栈桥固定段相连,所述栈桥固定段前端通过伸缩机构连有栈桥移动段,所述栈桥移动段前端上设有着床装置和斜梯；还包括运动补偿控制系统,所述运动补偿控制系统,包括滤波器模块和控制器模块。本发明解决了海上恶劣海况下人员的安全输送,又可提供电、水、油、泥浆的输送。(The invention discloses a telescopic trestle system and a control method thereof, wherein the telescopic trestle system is arranged on a supporting platform or a supporting ship and comprises a cylinder body arranged on the supporting platform or the supporting ship, the cylinder body is connected with a rotary chassis through a rotary mechanism, the rotary chassis is provided with a hydraulic pump station and a cab, the rotary chassis is connected with a trestle fixing section, the hydraulic pump station is connected with the trestle fixing section through an amplitude varying mechanism, the front end of the trestle fixing section is connected with a trestle moving section through a telescopic mechanism, and the front end of the trestle moving section is provided with a landing device and an inclined ladder; the motion compensation control system comprises a filter module and a controller module. The invention solves the problem of safe transportation of personnel under severe sea conditions at sea and can also provide the transportation of electricity, water, oil and slurry.)

1. The utility model provides a telescopic trestle system, installs in supporting platform or support on the ship, its characterized in that: the hydraulic landing platform comprises a cylinder body arranged on the supporting platform or the supporting ship, wherein the cylinder body is connected with a rotary chassis through a rotary mechanism, the rotary chassis is provided with a hydraulic pump station and a cab, the rotary chassis is connected with a trestle fixing section, the hydraulic pump station is connected with the trestle fixing section through a luffing mechanism, the front end of the trestle fixing section is connected with a trestle moving section through a telescopic mechanism, and the front end of the trestle moving section is provided with a landing device and an inclined ladder;

the motion compensation control system comprises a filter module and a controller module;

the filter module is used for estimating the six-degree-of-freedom motion of the supporting platform or the supporting ship;

and the controller module is used for inputting the filter module and calculating the target stroke of the amplitude variation mechanism, the target angle of the slewing mechanism and the target angle of the telescopic mechanism according to the six-degree-of-freedom motion state of the supporting platform or the supporting ship.

2. The telescopic trestle system of claim 1, wherein: the amplitude-changing mechanism comprises two oil cylinders connected to the hydraulic pump station, a piston rod on one oil cylinder is connected with the rotary chassis, and a piston rod on the other oil cylinder is connected with the trestle fixing section.

3. The telescopic trestle system of claim 1, wherein: the slewing mechanism comprises a driving device, a reduction box and a gear which are sequentially connected, and a slewing bearing arranged on the slewing chassis, wherein the gear is meshed with the slewing bearing.

4. The telescopic trestle system of claim 1, wherein: the telescopic mechanism comprises a driving device, a reduction box and a gear which are arranged on the front end of the trestle fixing section and are sequentially connected, and a rack arranged on the rear end of the trestle moving section, wherein the gear is meshed with the rack; or

The telescopic mechanism comprises a driving device, a reduction box and a steel wire rope reel which are arranged on the trestle fixing section and are connected in sequence, wherein the driving device, the reduction box and the steel wire rope reel are connected in sequence, and a steel wire rope on the steel wire rope reel is connected with the rear end of the trestle moving section.

5. The telescopic trestle system of claim 4, wherein: a plurality of idler wheels are further arranged between the front end of the trestle fixing section and the rear end of the trestle moving section.

6. A method of controlling the telescopic trestle system according to any of claims 1 to 5, characterized by: the motion compensation control comprises position compensation control and position contact force parallel compensation control;

the position compensation control is used for compensating the front end motion of the trestle moving section caused by the six-degree-of-freedom motion of the supporting platform or the supporting ship;

the position contact force parallel compensation control is to control the contact force at the front end of the moving segment of the trestle on the basis of the position compensation control;

the method comprises the steps of measuring the motion, contact force and a target set value of the front end of the moving section of the trestle in real time through a measuring and sensing system, calculating a joint command through kinematic inverse solution, converting the joint command to the motion of an actuator to calculate the target state of the actuator, controlling the target stroke of a luffing mechanism, the target angle of a slewing mechanism and the target angle of a telescopic mechanism, and feeding back the target stroke of the luffing mechanism, the target angle of the slewing mechanism and the measured value of the target angle of the telescopic mechanism in real time to realize the effect of external factors on the front end of the moving section of the trestle by applying the inverse motion of the external factor response motion to the front end of the moving section of the trestle.

7. The method for controlling a telescopic trestle system according to claim 6, wherein: the inverse kinematics solution calculation is specifically as follows:

determining a coordinate system of the front end of the movable section of the trestle

In the above formula, P_tipX,P_tipY,P_tipZIs {0} the position of the front end of the moving section of the trestle in a coordinate system, theta₁Angle of rotation theta₂The angle of the luffing mechanism is d3, the stroke of the telescopic mechanism is d 4, and the telescopic length between the fixed segment of the trestle and the movable segment of the trestle is L4;

after the position of the front end of the movable section of the trestle is known, the angle of the slewing mechanism, the angle of the luffing mechanism and the stroke of the telescopic mechanism can be calculated through a formula (2).

8. The method for controlling a telescopic trestle system according to claim 7, wherein: the relationship between the angle of the luffing mechanism and the stroke of the oil cylinder in the luffing mechanism is as follows:

γ+α+θ₂＝90° (4)

wherein

The following equations (3) and (4) show:

the relationship of the stroke of the oil cylinder in the luffing mechanism of the lower support oil cylinder is as follows:

wherein

The relationship between the rotation angle and the angle of the driving device in the rotation mechanism is as follows:

s_s＝iθ₁(7)

in the above formula, i is the transmission ratio of the rotation to the driving device in the rotation mechanism;

the relationship between the telescopic stroke and the angle of the driving device in the telescopic mechanism is as follows:

s_t＝i′d3 (8)

in the above formula, i' is a proportionality coefficient between the telescopic stroke and the driving device in the telescopic mechanism.

9. The method for controlling a telescopic trestle system according to claim 6, wherein: the joint-to-actuator motion transformation is as follows:

and calculating the target state of the actuator through a transformation formula (9) from the joint to the actuator, namely the target angle of the slewing mechanism, the target stroke of the luffing mechanism and the target angle of the telescopic mechanism.

10. The method for controlling a telescopic trestle system according to claim 9, wherein: the actuator adjusts the target angle and the stroke of the actuator by controlling the flow of the hydraulic oil of the proportional directional valve, and the specific PID control is as follows:

in the above formula, u is a control amount, K_p,K_i,K_dIs a parameter of PID, S_actIs a measure of the target angle and stroke of the actuator.

Technical Field

The invention relates to trestle equipment, in particular to a telescopic trestle system and a control method thereof, which are particularly suitable for a semi-submersible support platform, a maritime work support ship, a wind power operation and maintenance ship, a maritime work traffic ship, a navigation ship and a rescue ship.

Background

With the high-speed development of offshore wind power and oil exploitation industries, personnel alternation and maintenance personnel for offshore projects such as drilling platforms, FPSOs and wind power installations get on and off the ship, and traditionally, a cage, a ship side inclined ladder, a helicopter and the like are adopted for getting on and off the ship. But the problem of insufficient safety of the suspension cage is increasingly revealed, the ship side inclined ladder is influenced by wind and waves, the limiting conditions are too much, and the economy of the helicopter is too low.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a telescopic trestle system and a control method thereof, which solve the problem of safe transportation of personnel under severe sea conditions on the sea and can also provide transportation of electricity, water, oil and slurry.

In order to achieve the purpose, the invention adopts the following technical scheme:

on one hand, the telescopic trestle system is arranged on a supporting platform or a supporting ship and comprises a cylinder body arranged on the supporting platform or the supporting ship, wherein the cylinder body is connected with a rotary chassis through a rotary mechanism, the rotary chassis is provided with a hydraulic pump station and a cab, the rotary chassis is connected with a trestle fixing section, the hydraulic pump station is connected with the rear end of the trestle fixing section through an amplitude varying mechanism, the front end of the trestle fixing section is connected with a trestle moving section through a telescopic mechanism, and the front end of the trestle moving section is provided with a landing device and an inclined ladder;

the motion compensation control system comprises a filter module and a controller module;

the filter module is used for estimating the six-degree-of-freedom motion of the supporting platform or the supporting ship;

and the controller module is used for inputting the filter module and calculating the target stroke of the amplitude variation mechanism, the target angle of the slewing mechanism and the target angle of the telescopic mechanism according to the six-degree-of-freedom motion state of the supporting platform or the supporting ship.

The amplitude-changing mechanism comprises two oil cylinders connected to the hydraulic pump station, a piston rod on one oil cylinder is connected with the rotary chassis, and a piston rod on the other oil cylinder is connected with the trestle fixing section.

The slewing mechanism comprises a driving device, a reduction box and a gear which are sequentially connected, and a slewing bearing arranged on the slewing chassis, wherein the gear is meshed with the slewing bearing.

The telescopic mechanism comprises a driving device, a reduction gearbox and a gear which are arranged at the front end of the fixed section of the trestle and are sequentially connected, and a rack arranged at the rear end of the movable section of the trestle, wherein the gear is meshed with the rack or driven by an alternating current variable frequency motor or a hydraulic motor, and the motor is connected with an input shaft of the reduction gearbox through a quincunx elastic coupling (high-speed coupling). The wire rope reel is connected with the output shaft of the reduction box through a tooth-shaped reel coupler (low-speed coupler). The high-speed coupler and the winding drum coupler amplify driving torque generated by the motor through the reduction gearbox and then transmit the amplified driving torque to the winding drum, so that the driving torque is pulled by the steel wire rope to move forwards or backwards.

A plurality of idler wheels are further arranged between the front end of the trestle fixing section and the rear end of the trestle moving section.

In another aspect, the control method of the telescopic trestle system comprises a motion compensation control, a position compensation control and a position contact force parallel compensation control;

the position compensation control is used for compensating the front end motion of the trestle moving section caused by the six-degree-of-freedom motion of the supporting platform or the supporting ship;

the position contact force parallel compensation control is to control the contact force at the front end of the moving segment of the trestle on the basis of the position compensation control;

the method comprises the steps of measuring the motion, contact force and a target set value of the front end of the moving section of the trestle in real time through a measuring and sensing system, calculating a joint command through kinematic inverse solution, converting the joint command to the motion of an actuator to calculate the target state of the actuator, controlling the target stroke of a luffing mechanism, the target angle of a slewing mechanism and the target angle of a telescopic mechanism, and feeding back the target stroke of the luffing mechanism, the target angle of the slewing mechanism and the measured value of the target angle of the telescopic mechanism in real time to realize the effect of external factors on the front end of the moving section of the trestle by applying the inverse motion of the external factor response motion to the front end of the moving section of the trestle.

The inverse kinematics solution calculation is specifically as follows:

determining a coordinate system of the front end of the movable section of the trestle

In the above formula, P_tipX,P_tipY,P_tipZFor the position of the front end of the moving section of the trestle in the coordinate system {0}, θ₁Angle of rotation theta₂The angle of the luffing mechanism is d3, the stroke of the telescopic mechanism is d 4, and the telescopic length between the fixed segment of the trestle and the movable segment of the trestle is L4;

after the position of the front end of the movable section of the trestle is known, the angle of the slewing mechanism, the angle of the luffing mechanism and the stroke of the telescopic mechanism can be calculated through a formula (2).

The relationship between the angle of the luffing mechanism and the stroke of the oil cylinder in the luffing mechanism is as follows:

γ+α+θ₂＝90° (4)

wherein

The following equations (3) and (4) show:

the relationship of the stroke of the oil cylinder in the luffing mechanism of the lower support oil cylinder is as follows:

wherein

The relationship between the rotation angle and the angle of the driving device in the rotation mechanism is as follows:

s_s＝iθ₁(7)

in the above formula, i is the transmission ratio of the rotation to the driving device in the rotation mechanism;

the relationship between the telescopic stroke and the angle of the driving device in the telescopic mechanism is as follows:

s_t＝i′d3 (8)

in the above formula, i' is a proportionality coefficient between the telescopic stroke and the driving device in the telescopic mechanism.

The joint-to-actuator motion transformation is as follows:

and calculating the target state of the actuator through a transformation formula (9) from the joint to the actuator, namely the target angle of the slewing mechanism, the target stroke of the luffing mechanism and the target angle of the telescopic mechanism.

The actuator adjusts the target angle and the stroke of the actuator by controlling the flow of hydraulic oil of the proportional directional valve, and the specific PID control is as follows:

in the above formula, u is a control amount, K_p,K_i,K_dIs a parameter of PID, S_actIs a measure of the target angle and stroke of the actuator.

In the above technical solution, the telescopic trestle system and the control method thereof provided by the present invention have an active motion compensation capability, are adaptable to various sea conditions, have a highly redundant safety design, can ensure the safe transportation of personnel, can provide a contact (long time) or non-contact (short time) lap joint mode, are adaptable to various boat types, and the cylinder may be fixed or may be lifted, and the lifting includes: rack and pinion type, cylinder pin type, cylinder lift type, rail lift type, wire rope lift type, and the like. The telescopic trestle system is flexible in installation mode and is suitable for personnel transfer and rescue of a fixed target platform and a floating target platform.

Drawings

FIG. 1 is a front view of the telescoping trestle system of the present invention;

FIG. 2 is a top view of the telescoping trestle system of FIG. 1;

FIG. 3 is a control algorithm block diagram of the control method of the telescopic trestle system of the invention;

FIG. 4 is a schematic diagram of a trestle coordinate system calculated by inverse kinematics in the control method of the system of FIG. 3;

FIG. 5 is a graph of the amplitude transformer angle versus the travel of the oil cylinder in the amplitude transformer in the kinematic inverse solution calculation of FIG. 4;

fig. 6 is a graph showing the relationship between the stroke of the oil cylinder in the luffing mechanism of the lower support cylinder system.

FIG. 7 is a schematic illustration of a support platform or support vessel in six degrees of freedom;

figure 8 is a response graph of vessel wave frequency motion through the system.

Detailed Description

The technical scheme of the invention is further explained by combining the drawings and the embodiment.

Referring to fig. 1 to 2, the telescopic trestle system provided by the present invention is installed on a support platform or a support ship 100, and includes a cylinder 1 installed on the support platform or the support ship 100, the cylinder body 1 is connected with a rotary chassis 3 through a rotary mechanism 2, the rotary chassis 3 is provided with a hydraulic pump station 4 and a cab 5, the front end of the rotary chassis 3 is connected with a trestle fixing section 6 through a pin shaft, the hydraulic pump station 4 is connected with the trestle fixing section 6 through an amplitude variation mechanism 7, the front end of the trestle fixing section 6 is connected with a trestle moving section 9 through a telescopic mechanism 8, the trestle fixing section 6 and the trestle moving section 9 form a trestle, the front end of the trestle moving section 9 is provided with a landing device 10 and an inclined ladder 11 which are used for being lapped on a deck surface 200 of a target platform or a ship and providing buffer for personnel to go up and down and the trestle when being lapped. The cab 5 is arranged on the rotary chassis 3 and positioned on the side surface of the trestle fixing section 6 to control the operation of the trestle.

Preferably, the luffing mechanism 7 comprises two oil cylinders connected to the hydraulic pump station 4, a piston rod of one oil cylinder is connected with the rotary chassis 3, and a piston rod of the other oil cylinder is connected with the trestle fixing section 6 to provide the raising or lowering action of the trestle.

Preferably, the swing mechanism 2 includes a driving device (a hydraulic motor or a motor), a reduction box and a gear, which are connected in sequence, and a swing bearing 12 disposed on the swing chassis 3, wherein the gear is engaged with the swing bearing 12 for providing a swing action of the trestle.

Preferably, the telescopic mechanism 8 includes a driving device (a hydraulic motor or a motor), a reduction box, a gear or a telescopic steel wire rope driving drum which are arranged at the front end of the trestle fixing section 6 and connected in sequence, and a rack arranged at the rear end of the trestle moving section 9, the gear is engaged with the rack, and the gear winds along the following path after moving forward or backward along the rack arranged at the rear end of the trestle moving section 9 or winding out the steel wire rope from the telescopic driving drum: mechanism reel → cable tensioning device → fixed end and bend pulley on the telescopic truss → return to reel. The running direction of the telescopic truss can be switched by changing the steering of the motor. .

Preferably, a plurality of rollers are further arranged between the front end 6 of the trestle fixing section and the rear end 7 of the trestle moving section, and are used for assisting the gear to move forward or backward along a rack arranged at the rear end of the trestle moving section 9.

Preferably, the motion compensation control system further comprises a filter module and a controller module.

Preferably, the filter module is used to estimate the six degree of freedom motion of the support platform or support vessel 100.

Preferably, the controller module is an input of the filter module, and calculates a target stroke of the luffing mechanism 7, a target angle of the slewing mechanism 2, and a target angle of the telescoping mechanism 8 according to a six-degree-of-freedom motion state of the support platform or the support ship 100.

Preferably, the luffing mechanism 7, the slewing mechanism 2 and the telescopic mechanism 8 realize the overlapping, working, evacuating and locking of the trestle through the motion compensation control system.

In addition, the hydraulic system of the telescopic trestle system adopts an energy conversion device consisting of an energy accumulator, a hydraulic pump-motor and an oil cylinder to store/release the energy of the trestle hydraulic system.

The electrohydraulic system realizes the safety of the trestle through the design of a redundancy scheme, and two main motors are configured to respectively drive hydraulic pump sets with the same function; the UPS is configured to ensure that the control system is continuously effective in the switching process of the main power supply and the emergency power supply; the energy accumulator is used as an energy-absorbing and energy-storing device, and the trestle can be safely withdrawn and stopped at a safe position by depending on the energy stored by the energy accumulator under the condition that a power supply fails.

The hydraulic system adopts electro-hydraulic proportional control to realize proportional change of flow and pressure along with input control signals. The electric control system realizes closed loop control by acquiring sensor signals of the action execution terminal, processing system signals and controlling given correction and adjusting power output of the hydraulic system, thereby meeting the requirement of a relative motion compensation function between the electric control system and a target floating body.

As shown in fig. 3, a control method of a telescopic trestle system, the motion compensation control includes a position compensation control and a position contact force parallel compensation control;

preferably, the position compensation control is used to compensate for the motion of the front end of the trestle movement section 9 (i.e. the end of the trestle) due to six degrees of freedom motion of the support platform or vessel 100.

Preferably, the position contact force parallel compensation control is that the contact force at the tail end of the trestle is controlled on the basis of the position compensation control.

The method comprises the steps of measuring the motion and contact force of the tail end of the current trestle in real time through a measuring and sensing system, calculating a joint command through kinematic inverse solution, converting the joint command to the motion of an actuator to calculate the target state of the actuator, controlling the target stroke of an amplitude variation mechanism 7, the target angle of a rotary mechanism 2 and the target angle of a telescopic mechanism 8, feeding back the target stroke of the amplitude variation mechanism 7, the target angle of the rotary mechanism 2 and the measured value of the target angle of the telescopic mechanism 8 in real time, and counteracting the influence of external factors on the tail end of the trestle by applying reverse motion of response motion of the external factors (such as waves) to the tail end of the trestle.

Preferably, the measurement sensing system is mainly used for measuring the motion of the ship with six degrees of freedom, wherein the position reference system (such as DGPS) is used for measuring the motion of the ship in a horizontal plane; a motion reference unit (e.g. MRU) for measuring the vessel's heave, pitch and roll motions in the vertical plane; a heading angle measurement (e.g. an electric compass) for measuring the heading angle of the vessel.

As shown in fig. 4 and 5, the inverse kinematics solution is calculated as follows:

determining a trestle coordinate system

In the above formula, P_tipX,P_tipY,P_tipZIs the position of the end of the 0 trestle in the coordinate system₁At 2 degrees of rotation, theta₂The angle of the luffing mechanism is 7 degrees, d3 is the stroke of the telescopic mechanism 8, and L4 is the fixed section 6 and the fixed sectionThe telescopic length between the trestle moving sections 9, L1 is the height of the cylinder body 1.

After the tail end position of the trestle is known, the angle of the slewing mechanism 2, the angle of the luffing mechanism 7 and the stroke of the telescopic mechanism 8 can be calculated through a formula (2).

As shown in fig. 5, the relationship between the angle of the horn 7 and the stroke of the oil cylinder in the horn 7 is as follows:

γ+α+θ₂＝90° (4)

wherein

The following equations (3) and (4) show:

in the above formulae (3), (4) and (5), s_lIs the total length of the amplitude variation oil cylinder, d is the height of the main bridge, and theta₂The variable amplitude angle is formed, wherein a is the height of the frame A, b is the distance from the lower hinge point to the upright post of the frame a, and c is the distance from the lower hinge point to the rear hinge point of the upper oil cylinder.

As shown in fig. 6, the relationship of the stroke of the oil cylinder in the luffing mechanism for the lower support cylinder is as follows:

wherein

In the above formula, the figure corresponds to a luffing mechanism in the manner of a lower support cylinder, s_lIs the total length of the luffing cylinder, a₁、a₂、b₁、b₂The relative position of the hinge point of the oil cylinder and the hinge point of the luffing mechanism is arranged.

Preferably, the relationship between the rotation angle and the angle of the driving device in the rotation mechanism 2 is as follows:

s_s＝iθ₁(7)

in the above formula, i is the transmission ratio between the rotation and the driving device in the rotation mechanism 2.

Preferably, the relationship between the telescopic stroke and the angle of the driving device in the telescopic mechanism 8 is as follows:

s_t＝i′d3 (8)

in the above formula, i' is a proportionality coefficient between the telescopic stroke and the driving device in the telescopic mechanism 8.

Preferably, the joint-to-actuator motion transformation is as follows:

and calculating the target state of the actuator through a transformation formula (9) from the joint to the actuator, namely the target angle of the slewing mechanism, the target stroke of the luffing mechanism and the target angle of the telescopic mechanism.

Preferably, the actuator adjusts the target angle and the stroke of the actuator by controlling the flow of hydraulic oil of the proportional directional valve, and the specific pid control is as follows:

in the above formula, u is a control amount, K_p,K_i,K_dIs a parameter of PID, S_actIs a measure of the target angle and stroke of the actuator.

As shown in fig. 7, in the hull coordinate system, the surging, swaying and heaving in the six-degree-of-freedom motion of the ship are rigid translation, the translation of any point on the rigid body (hull 300) is the same, and the compensation of the motion of the part can directly make the gravity center of the ship move in the opposite direction, namely:

wherein x_wv,y_wv,z_wvWhich is the surging, swaying and heaving of the hull 300.

The point P is an arbitrary point on the hull 300, and its position P from the origin of coordinates (center of gravity) is [ x y z [ ]]^TThe transformation of the position of the P point due to the ship pitch, roll and yaw is:

P′＝J₁P (12)

wherein P' is the position of the rigid system after rotation, J₁Euler angle rotation matrix:

the displacement caused by the rotation is:

the compensation of the rotational movement is thus:

therefore, in summary, the target positions at the tail end of the moving trestle for compensating the six-degree-of-freedom motion of the ship are as follows:

note that: the X axis of the hull coordinate system is the Y axis of the trestle coordinate system, and the Y axis of the hull coordinate system is the X axis of the trestle coordinate system.

In addition, in practical cases, it is also possible to introduce a contact force at the end of the bridge into the motion compensation control system, that is, by applying a suitable contact force on the bridged object, the control of the contact force is realized by increasing the displacement of the bridge in the x direction:

wherein x_fIs the displacement in the X direction in the trestle coordinate system {0 }.

The control method of the contact force is as follows:

x_f＝K_p(F_d-F_act)+K_i∫(F_d-F_act)dt (17)

wherein F_d,F_actFor the target contact force and the actual contact force, K_p,K_iProportional and integral term parameters of the controller.

As shown in fig. 8, the sensor measurement data is filtered and used as input data for the controller. The system separates the wave frequency motion of the ship from the measured data through a KALMAN filtering algorithm. Since the KALMAN filtering is a model-based filtering algorithm, the wave frequency motion of the ship is modeled first.

Assuming that the wave height and the motion of the ship in a certain degree of freedom can be approximated by a linear system, the output spectral density S of the ship in a certain degree of freedom_y(ω) is equal to the input spectral density S_ζ(ω) times G (iw), i.e. S, of the system_y(ω)＝S_ζ(ω)|G(iω)|²G (i ω) is RAO (ω, β), and RAO (ω, β) can be calculated by software.

Thus, it is possible to provide

If the input spectrum and transfer function are known, the constants in the equation can be obtained by least squares method, and can be used as parameters for online identification.

Transforming the transfer function to a state space model:

wherein: inputting n to represent zero mean Gaussian white noise; y is_wRepresenting wave frequency motion in the direction of each degree of freedom.

It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be used as a limitation of the present invention, and that changes and modifications to the above described embodiments are within the scope of the claims of the present invention as long as they are within the spirit and scope of the present invention.