CN113254870A - Parameter identification method and computer-readable storage medium - Google Patents

Parameter identification method and computer-readable storage medium Download PDF

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CN113254870A
CN113254870A CN202110546255.8A CN202110546255A CN113254870A CN 113254870 A CN113254870 A CN 113254870A CN 202110546255 A CN202110546255 A CN 202110546255A CN 113254870 A CN113254870 A CN 113254870A
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谌栋梁
黄彦文
秦一飞
张园
陈杰宇
王晓飞
谢颖
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Shanghai Zhenghua Heavy Industries Co Ltd
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Abstract

The invention discloses a parameter identification method and a computer readable storage medium, wherein the parameter identification method comprises the following steps: s101: after the ship is in a preset state, respectively receiving a position parameter, a speed parameter and an initial value of a first thrust provided by a propulsion system to the ship, wherein the position parameter and the speed parameter correspond to a parameter to be identified at an initial moment, and setting an initial filtering parameter; s102: adjusting the operating handle to place the watercraft in a first state; s103: receiving a position parameter at the current moment and a current value of the first thrust; s104: according to the initial values of the position parameter, the first thrust, the current value and the speed parameter, a motion model is constructed, and a first state vector after observation at the current moment and a first covariance corresponding to the first state vector are calculated; s105: judging whether the first covariance meets a stable condition; if so, acquiring a parameter to be identified according to the observed first state vector; otherwise, return to execute S103. The parameter identification method provided by the invention can effectively identify the key parameters, and is simple and easy to operate.

Description

Parameter identification method and computer-readable storage medium
Technical Field
The present invention relates to the field of dynamic positioning control, and more particularly, to a parameter identification method and a computer-readable storage medium.
Background
The ship dynamic positioning system is an indispensable key technology for developing deep sea operation, and is indispensable in the fields of offshore oil and gas resource exploration and development, pipe laying operation, offshore oil operation platform assembly and disassembly, large-scale offshore military equipment engineering and the like. The motion filtering module has the main task of filtering signals such as position, heading, attitude and the like measured by the sensing system, separating low-frequency and high-frequency parts in the motion of the ship, accurately estimating the position, the speed and the external load of the ship and providing a basis for the motion control of the ship.
Most algorithms related in the existing dynamic positioning ship filtering algorithm are filtering based on ship motion models, and a dynamic positioning control system adopting the algorithms needs to determine two main types of model parameters related in the algorithms before deployment and use, namely ship inertia parameters and viscous water power parameters, but the existing method for distinguishing the two parameters is complex, cannot simply and effectively identify the two parameters on line, and is not beneficial to the deployment of the dynamic positioning control system.
Disclosure of Invention
The invention aims to solve the problem that a ship inertia parameter and viscous water dynamic parameter distinguishing method in the prior art is complex, and provides a parameter identification method of a dynamic positioning filtering model, which can simply and effectively carry out online identification on unknown inertia parameters and viscous water dynamic parameters related to a ship filtering algorithm model, thereby providing convenience for the deployment of a dynamic positioning control system.
Based on this, the embodiment of the invention discloses a parameter identification method, which is used for a ship dynamic positioning control system filter and comprises the following steps:
s101: after the ship is in a preset state, receiving an initial value of a position parameter, an initial value of a speed parameter and an initial value of a first thrust provided to the ship by a propulsion system, wherein the initial values of the position parameter, the speed parameter and the first thrust are measured by a measurement system at an initial moment, the initial values of the position parameter and the speed parameter are corresponding to parameters to be identified, the initial values of the first thrust are measured by the measurement system at the initial moment, a filter of the ship is set to be in an initial state, and initial filtering parameters are set;
s102: adjusting an operating handle of the dynamic positioning control system to place the vessel in a first state;
s103: receiving the current value of the position parameter corresponding to the parameter to be identified and the current value of the first thrust provided by the propulsion system to the ship, which are measured by the measurement system at the current moment;
s104: according to the received initial value of the speed parameter, the initial value and the current value of the position parameter and the initial value and the current value of the first thrust, a motion model corresponding to the parameter to be identified is constructed, and according to the motion model and the initial filter parameter, a first observed state vector at the current moment and a first observed covariance corresponding to the first observed state vector are calculated;
s105: judging whether the observed first covariance meets a stable condition;
if so, acquiring a parameter to be identified according to the observed first state vector;
otherwise, return to execute S103.
According to another embodiment of the present invention, the initial filter parameter is an initial first state vector and an initial first covariance corresponding to the initial first state vector.
According to another embodiment of the present invention, step S104 includes:
determining the interval time between the current measurement and the last measurement of the measurement system;
constructing a one-dimensional motion matrix equation corresponding to the parameter to be identified according to the initial value and the current value of the position parameter, the initial value of the speed parameter and the initial value and the current value of the first thrust;
on the basis of the initial first state vector, performing integral solution on the one-dimensional motion matrix equation to obtain a first state vector at the current moment;
calculating a one-step transfer matrix according to a one-dimensional motion matrix equation, and calculating and obtaining a first covariance corresponding to a first state vector at the current moment based on the one-step transfer matrix and the initial first covariance;
and observing the first state vector and the corresponding first covariance at the current moment to obtain the observed first state vector and the observed first covariance at the current moment.
According to another embodiment of the present invention, step S105 includes:
judging whether the observed first covariance at the current moment meets a stable condition;
if so, acquiring a parameter to be identified according to the observed first state vector at the current moment;
otherwise, the initial first state vector is updated to the observed first state vector at the current time, the initial first covariance is updated to the observed first covariance at the current time, and the process returns to step S103.
According to another embodiment of the present invention, the one-dimensional motion matrix equation is:
Figure BDA0003073617860000021
wherein s is a position parameter corresponding to the parameter to be identified, u is a velocity parameter corresponding to the parameter to be identified, X is the parameter to be identified, τthruProviding a first thrust corresponding to the parameter to be identified to the vessel for the propulsion system, m being an inertia parameter, C being a viscous hydrodynamic parameter, WuFor uncertainty interference of kinetic equations, WXIs the uncertainty interference of the parameter to be identified.
According to another specific embodiment of the present invention, the parameters to be identified include inertia parameters to be identified and viscous water kinetic parameters to be identified;
when the parameter to be recognized is the inertia parameter to be recognized, step S102 includes:
controlling the operating handle to continuously and alternately operate so that the difference value between the speed parameter corresponding to the inertia parameter to be identified and the ocean current speed corresponding to the inertia parameter to be identified is alternately changed between a positive value and a negative value;
when the parameter to be identified is the viscous hydrodynamic parameter to be identified, step S102 includes:
the operating handle is adjusted to maintain a certain thrust in the respective direction of the propulsion system of the vessel.
According to a further particular embodiment of the present invention,
when the inertia parameter to be identified is the sum of the ship mass and the transverse or longitudinal additional mass, and/or the viscous hydrodynamic parameter to be identified is a transverse or longitudinal secondary damping coefficient, the preset state in the step S101 is that the operating handle of the dynamic positioning control system is maintained at the zero position for a first preset time; before step S101, the parameter identification method further includes:
setting the operation mode of the ship as automatic heading, adjusting an operation handle of the dynamic positioning control system to a zero position so that the thrust generated by the propulsion system of the ship in the transverse direction and the longitudinal direction is zero while the heading is kept, and keeping the operation handle at the zero position for a first preset time;
when the inertia parameter to be identified is the sum of the inertia moment of the ship around the vertical direction and the additional inertia moment, and/or the viscous water power parameter to be identified is the secondary yaw damping coefficient, the preset state in the step S101 is the second preset time for the ship to float freely.
According to another embodiment of the present invention, the first preset time and/or the second preset time is 20 min.
According to another embodiment of the present invention, when the parameter to be identified is the sum of the ship mass and the longitudinal additional mass, and/or the parameter to be identified is the longitudinal secondary damping coefficient, the speed parameter is the longitudinal flow velocity of the ship, the position parameter is the longitudinal displacement of the ship, and the first thrust is the longitudinal thrust provided by the propulsion system to the ship;
when the parameter to be identified is the sum of the ship mass and the transverse additional mass and/or the viscous hydrodynamic parameter to be identified is a transverse secondary damping coefficient, the speed parameter is the transverse flow velocity of the ship, the position parameter is the transverse displacement of the ship, and the first thrust is the transverse thrust provided by the propulsion system to the ship;
when the parameter to be identified is the sum of the moment of inertia of the ship around the vertical direction and the additional moment of inertia and/or the viscous hydrodynamic parameter to be identified is a secondary heading damping coefficient, the speed parameter is the heading rotating speed of the ship, the position parameter is the heading angular displacement of the ship, and the first thrust is the heading moment provided by the propulsion system to the ship.
Accordingly, the embodiment of the invention also discloses a computer-readable storage medium, wherein the computer-readable storage medium stores instructions which, when executed on a computer, cause the computer to execute the parameter identification method.
Compared with the prior art, the invention has the following technical effects:
the parameter identification method provided by the invention can effectively identify the key parameters in the ship motion model of the dynamic positioning ship control system filter, has no special requirements on the test environment in the implementation process, does not need extra early-stage calculation, and is simple and easy to operate.
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FIG. 1 illustrates a flow chart of a parameter identification method provided by the present invention;
FIG. 2 shows a schematic representation of the northeast coordinate system and the moving coordinate system of the attached hull provided by the present invention;
FIG. 3 shows a schematic diagram of an electronic device provided by the present invention;
FIG. 4 shows a schematic diagram of a system on chip provided by the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure. While the invention will be described in conjunction with the preferred embodiments, it is not intended that features of the invention be limited to these embodiments. On the contrary, the invention is described in connection with the embodiments for the purpose of covering alternatives or modifications that may be extended based on the claims of the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be practiced without these particulars. Moreover, some of the specific details have been left out of the description in order to avoid obscuring or obscuring the focus of the present invention. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
It should be noted that in this specification, like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.
In the description of the present embodiment, it should be noted that the terms "first", "second", "third", "fourth", "fifth", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
In the description of the present embodiment, it should be further noted that, unless explicitly stated or limited otherwise, the terms "disposed" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present embodiment can be understood in specific cases by those of ordinary skill in the art.
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As shown in fig. 1, the present invention provides a parameter identification method, which may be used for a filter of a dynamic positioning control system of a ship, to identify key parameters (including an inertia parameter and a viscous hydrodynamic parameter) in a dynamic positioning filter model, and the parameter identification method includes the following steps:
s101: after the ship is in a preset state, receiving an initial value of a position parameter, an initial value of a speed parameter and an initial value of a first thrust provided to the ship by a propulsion system, wherein the initial values of the position parameter, the speed parameter and the first thrust are measured by a measurement system at an initial moment, the initial values of the position parameter, the speed parameter and the first thrust are corresponding to the parameters to be identified, the filter of the ship is set to be in an initial state, and initial filtering parameters are set.
Specifically, the initial filter parameters include an initial first state vector and an initial first covariance corresponding to the initial first state vector. The setting of the preset state is related to the type of the parameter to be identified, and when the parameter to be identified is the sum of the ship mass and the transverse additional mass or the sum of the ship mass and the longitudinal additional mass, or the transverse secondary damping coefficient or the longitudinal secondary damping coefficient, the preset state may be to keep the operating handle of the dynamic positioning control system of the ship at the zero position for a period of time (which may be set to be kept at the zero position for a first preset time, and further, the first preset time may be set to be 20min), at this time, before step S101, the parameter identification method may further include:
setting the operation mode of the ship to be heading automatic, adjusting an operation handle of the dynamic positioning control system to a zero position so that the thrust generated by the ship in the transverse direction and the longitudinal direction is zero while the ship propulsion system keeps heading, and keeping the operation handle at the zero position for a first preset time.
And when the parameter to be identified is the sum of the moment of inertia of the ship around the vertical direction and the additional moment of inertia or the secondary damping coefficient of the turning, the stable condition can be the state of the ship after the ship floats freely for a period of time, the ship can be set to keep floating freely for a second preset time, and similarly, the second preset time can also be set to be 20 min.
The three parameters of the sum of the ship mass and the transverse additional mass, the sum of the ship mass and the longitudinal additional mass and the sum of the inertia moment of the ship around the vertical direction and the additional inertia moment are inertia parameters, and the three parameters of the transverse secondary damping coefficient, the longitudinal secondary damping coefficient and the fore-turning secondary damping coefficient are viscous hydrodynamic parameters.
Similarly, the selection of the position parameter, the speed parameter and the first thrust is related to the type of the parameter to be identified. For example, when the parameter to be identified is the sum of the ship mass and the longitudinal additional mass or the longitudinal secondary damping coefficient, the speed parameter is the longitudinal flow velocity of the ship, the position parameter is the longitudinal displacement of the ship, and the first thrust is the longitudinal thrust provided by the propulsion system to the ship; when the parameter to be identified is the sum of the ship mass and the transverse additional mass or the transverse secondary damping coefficient, the speed parameter is the transverse flow velocity of the ship, the position parameter is the transverse displacement of the ship, and the first thrust is the transverse thrust provided by the propulsion system to the ship; when the parameter to be identified is the sum of the moment of inertia of the ship around the vertical direction and the additional moment of inertia or the secondary heading damping coefficient, the speed parameter is the heading rotating speed of the ship, the position parameter is the heading angular displacement of the ship, and the first thrust is the heading moment provided by the propulsion system to the ship. The flow speed parameter, the position parameter and the first thrust of the ship can be obtained through a measuring system arranged on the ship, for example, the transverse/longitudinal displacement can be obtained through a GPS positioner, the heading angular displacement can be obtained through an electric compass, and the first thrust applied to the ship body by all the thrusters can be calculated in real time through numerical values measured by related sensors.
S102: an operating handle of the dynamic positioning control system is adjusted to place the watercraft in a first state.
In particular, the setting of the first state is also related to the type of parameter to be identified.
When the parameter to be identified is an inertia parameter (such as the sum of the ship mass and the transverse additional mass, the sum of the ship mass and the longitudinal additional mass, or the sum of the inertia moment of the ship around the vertical direction and the additional inertia moment), the first state is a state in which the difference between the speed parameter corresponding to the inertia parameter to be identified and the ocean current speed in the corresponding direction changes alternately between a positive value and a negative value, and then the step S102 specifically includes: and controlling the operating handle to continuously and alternately operate so that the difference value between the speed parameter corresponding to the inertia parameter to be identified and the ocean current speed in the corresponding direction is alternately changed between a positive value and a negative value. Specifically, when the inertia parameter to be identified is the sum of the ship mass and the longitudinal additional mass, an operation handle of the dynamic positioning control system is adopted to continuously and alternately operate forwards and backwards, so that the difference value between the ship longitudinal speed and the ocean current longitudinal flow speed is rapidly changed between a positive value and a negative value; when the inertia parameter to be identified is the sum of the ship mass and the transverse additional mass, an operating handle of a dynamic positioning control system is adopted to continuously and alternately operate leftwards and rightwards, so that the difference value between the longitudinal speed of the ship and the transverse flow velocity of the ocean current is rapidly changed between a positive value and a negative value; when the inertia parameter to be identified is the sum of the inertia moment of the ship around the vertical direction and the additional inertia moment, the operation handle of the dynamic positioning control system is adopted to continuously and alternately perform clockwise and anticlockwise turning operation, so that the difference value between the turning speed of the ship and the rotation speed of the ocean current around the vertical direction is alternately changed between positive and negative, and the rotation speed of the ocean current around the vertical direction is not considered (namely, the rotation speed of the ocean current around the vertical direction is assumed to be zero), so that the step S102 at the moment is to continuously and alternately perform clockwise and anticlockwise turning operation by the operation handle of the dynamic positioning control system, so that the turning speed of the ship is alternately changed between positive and negative.
Specifically, the ocean current longitudinal flow velocity and the ocean current transverse flow velocity can be obtained by the following method: the dynamic positioning control system deployed by a ship but not accurately estimating parameters is adopted, the ship operation mode is set as heading automatic, the position is freely controlled by a handle, an operation handle of the dynamic positioning control system is operated to a zero position, so that the ship propeller keeps heading while the thrust generated transversely and longitudinally is zero, and the longitudinal speed and the transverse speed of the ship are recorded as the longitudinal flow velocity of ocean current and the transverse flow velocity of ocean current respectively after the state is kept for 20 minutes.
It will be understood by those skilled in the art that the lateral velocity and the longitudinal velocity of the ocean current can be directly measured, but compared with the direct measurement of the lateral velocity and the longitudinal velocity of the ocean current, the measurement in this embodiment is that the lateral velocity and the longitudinal velocity of the ship after the ship is kept in a certain state for a certain period of time are approximately used as the ocean current velocity, and the measurement process is simpler.
When the parameter to be identified is a viscous hydrodynamic parameter (such as a transverse secondary damping coefficient, a longitudinal secondary damping coefficient or a turning secondary damping coefficient), step S102 includes: the operating handle is adjusted to maintain a certain thrust in the respective direction of the propulsion system of the vessel. Specifically, when the viscous hydrodynamic parameter to be identified is a longitudinal secondary damping coefficient, a longitudinal fixed value is given by an operating handle of a dynamic positioning control system, so that the ship propulsion system maintains a certain thrust in the longitudinal direction; when the viscous hydrodynamic parameter to be identified is a transverse secondary damping coefficient, a transverse fixed value is given by adopting a power positioning control system operating handle, so that the ship can maintain a certain thrust in the transverse direction; when the viscous hydrodynamic parameter to be identified is a secondary heading turning damping coefficient, a constant heading turning instruction is given by adopting a dynamic positioning control system operating handle, so that the ship maintains a certain heading turning moment in the longitudinal direction. In particular, the above-mentioned given transverse/longitudinal reference value is not particularly critical, and is a value that is related to the size of the vessel and generally does not exceed a value that is generally equal to or greater than the size of the vessel
Figure BDA0003073617860000071
And L is the ship length.
S103: the method includes receiving a current value of a position parameter corresponding to a parameter to be identified measured by a measurement system at a current time and a current value of a first thrust provided to the vessel by a propulsion system.
Specifically, as described above, when the parameter to be identified is an inertia parameter or a viscous hydrodynamic parameter in the lateral or longitudinal direction, the displacement of the ship in the lateral or longitudinal direction may be acquired using the GPS locator, and when the parameter to be identified is an inertia moment or a yaw secondary damping coefficient of the ship around the vertical direction, the yaw displacement of the ship may be acquired using the compass. The speed parameter and the first thrust may be measured by respective sensors.
S104: and respectively constructing a motion model corresponding to the parameter to be identified according to the received initial value of the speed parameter, the received initial value and the received current value of the position parameter and the received initial value and the received current value of the first thrust, and calculating an observed first state vector at the current moment and an observed first covariance corresponding to the observed first state vector according to the motion model and the initial filter parameter.
S105: judging whether a stable condition is met or not according to the observed first covariance;
if yes, executing step S106;
otherwise, return to execute S103.
Step S106: and acquiring the parameter to be identified according to the observed first state vector.
The invention provides a set of online identification method for key parameters based on a ship motion model applied to a dynamic positioning ship control system filter, and the method has no special requirements for test environment in the implementation process, does not need extra early-stage calculation, and is simple and easy to operate.
Specifically, as shown in FIG. 2, the present invention relates to two coordinate systems, O-xyz and G-x ' y ' z ', where O-xyz is a global fixed coordinate system (also called the Northeast coordinate system) with the x-axis pointing to true north, the y-axis pointing to true east, and the z-axis (not shown) pointing vertically downward as is customary with the right-handed system; g-x ' y ' z ' is a moving coordinate system attached to the ship body, the coordinate origin G is located at the center of gravity of the ship, the x ' axis points to the bow along the longitudinal direction of the ship, the y ' axis points to the starboard of the ship, and the z ' axis (not shown in the figure) is vertically downward, namely the directions of the z axis and the z ' axis are vertically downward. Aiming at the condition that the ship speed of a dynamic positioning ship or an ocean platform is lower under the working conditions of position and heading automatic control, the dynamic positioning ship has the following ship motion models:
Figure BDA0003073617860000081
Figure BDA0003073617860000082
wherein xOG、yOGPhi respectively represents the north position, the east position and the heading angle of the gravity center of the ship under a northeast coordinate system, g, v and r respectively represent the longitudinal speed, the transverse speed and the heading speed of the ship, gc、vcLongitudinal and transverse flow velocities of the ocean current relative to the vessel, Xwind、Ywind、NwindWind is respectively in the transverse direction and the longitudinal direction of the ship,Force/moment applied in the direction of turning bow; xwave、Ywave、NwaveForce/moment applied by ocean current waves in three freedom directions of the ship in the transverse direction, the longitudinal direction and the heading direction are respectively; xP、YP、NPForces/moments are applied to the propeller in the directions of the three degrees of freedom.
The parameters that need to be determined by sea trial in this model are as follows: m isx、my、Izz、Xuu、Yvv、Nrr. Wherein m isx、my、IzzAs a parameter of inertia, Xuu、Yvv、NrrIs a viscous water kinetic parameter. In particular, mxIs the sum of the ship's mass and the longitudinal additional mass, myFor the sum of the ship's mass and the transverse additional mass, IzzIs the sum of the moment of inertia and the additional moment of inertia, X, of the vessel about the z' -axisuu、Yvv、NrrThe longitudinal secondary damping coefficient, the transverse secondary damping coefficient and the bow turning secondary damping coefficient of the ship are respectively.
Further, for a continuous system as shown below
Figure BDA0003073617860000083
Wherein a is a state vector, d (t) is a control vector, w is an interference vector, and assuming that the interference vector w is white noise, the covariance of the noise w is Q (t), and Γ is an influence matrix of the noise w. Equation (3), also known as a prediction model for Kalman filtering, assumes that the state variables and covariances of the system at time t are at、PtAfter a small time interval Δ t has elapsed (assuming that the system is not observed during this process and the control variable is known during this time interval), the system state variable at time t + Δ t may be estimated by the following equation:
at+Δt＝Integ[f(a,d(t)),Δt,at] (4)
Figure BDA0003073617860000084
wherein Integ represents [ alpha ], [ beta ], [ alpha ], [ beta ], [ alpha ], [ beta ] and [ alpha ], [ beta ], [ alpha ], [ beta ] and [ alpha ], [ alpha ] is a]The ordinary differential equation represented in (1) is subjected to integral solution, and a 4-order Longgo-Kutta method is adopted for integration in the invention. Phit,t+ΔtFor a one-step transition matrix, the following formula can be used to calculate:
Figure BDA0003073617860000091
where I is an identity matrix in the same dimension as the state vector a.
Specifically, a is a for the state variable and covariance described by equation (3) at time t, respectivelyt、dtIf the system is subjected to observation as shown in the formula (7)
b(t)＝h(a,t)+e(t) (7)
Where e (t) is white noise of intensity R (t) and h (a, t) is the observation equation. The corrected system state variable is then calculated via the observation vector b (t)
Figure BDA0003073617860000092
And its covariance
Figure BDA0003073617860000093
Can be calculated by the following formula:
Figure BDA0003073617860000094
Figure BDA0003073617860000095
Kt＝PtHt T[HtPtΗt T+R(t)]-1 (10)
wherein, the observation matrix HtIs composed of
Figure BDA0003073617860000096
Further, in order to perform parameter identification by adopting a kalman filtering method, decoupling three-degree-of-freedom horizontal motion of the ship to obtain a one-dimensional motion model for parameter identification:
Figure BDA0003073617860000097
wherein s is a position parameter corresponding to the parameter to be identified, u is a velocity parameter corresponding to the parameter to be identified, X is the parameter to be identified, τthruProviding a first thrust corresponding to the parameter to be identified to the vessel for the propulsion system, m being an inertia parameter, C being a viscous hydrodynamic parameter, WuFor uncertainty interference of kinetic equations, WXIs the uncertainty interference of the parameter to be identified.
Figure BDA0003073617860000098
The representative X is derived over time,
Figure BDA00030736178600000911
representing the derivative of the displacement s with respect to time,
Figure BDA0003073617860000099
representing the derivative of speed u with respect to time.
Specifically, when the parameter to be identified is an inertia parameter, the one-dimensional motion model for identifying the inertia parameter is specifically:
Figure BDA00030736178600000910
equation (12) is a general model for identifying inertia parameters, [ sm [ s ] m ]]TRepresents the state variable of the system, i.e. x in equation (3). Where s represents the displacement, u represents the velocity, m represents the inertia parameter to be identified,
Figure BDA0003073617860000101
representing the derivative of the displacement s with respect to time,
Figure BDA0003073617860000102
representing the derivative of the speed u with respect to time,
Figure BDA0003073617860000103
representing the derivative of the inertia parameter m with respect to time. Tau isthruIs the input variable of the system, i.e. d (t), [ w ] in the formula (3)u wm]TIs a disturbance variable, i.e. w in equation (3), the component w of whichuRepresents the uncertainty interference of the kinetic equation, wmRepresenting the uncertainty perturbation of the inertia parameter to be identified. And C is a viscous water kinetic parameter. This equation is actually written as a vector equation for three equations. The 1 st equation (i.e., the equation represented by the first row of the matrix) is the differential of the displacement, i.e., velocity, the second equation is the acceleration multiplied by mass, which is equal to the external force, and the third equation is the assumption that the mass of the object is an indeterminate quantity. Thus for translational motion (i.e. motion of the vessel in the lateral or longitudinal direction) s represents displacement, u represents velocity, m represents the sum of mass and additional mass, and for rotational motion (i.e. rotation of the vessel about the vertical direction) s represents angular displacement, u represents angular velocity, m represents the sum of moment of inertia and additional moment of inertia. w is auRepresents an uncertain disturbance of the kinetic equation, i.e. an uncertain force (moment for rotational motion), and therefore its effect on acceleration is divided by m.
For equation (12), a one-step transition matrix Φ can be derivedt,t+ΔtThe calculation formula of (2) is as follows:
Figure BDA0003073617860000104
in particular, as mentioned above, prior to identifying the inertia parameters, the vessel is typically allowed to drift freely for a period of time such that the velocity of the target vessel coincides with the velocity of the offshore region. For equation (12), the sum m of the ship's mass and the longitudinal additional massxThis is oneWhen identifying the parameters, u in the formula (12) represents the longitudinal speed of the ship with respect to the sea, τthruRepresenting the longitudinal thrust exerted by the propellers on the hull, m representing the parameter m to be identifiedxAnd C is Xuu(ii) a To myWhen the identification is performed, u in the formula (12) represents the lateral velocity of the ship with respect to the sea, τthruRepresenting the transverse thrust exerted by the propellers on the hull, m representing the parameter m to be identifiedyC is Yvv(ii) a In identifying the moment of inertia, u in equation (12) represents the ship heading speed, τthruRepresenting the yaw moment applied to the hull by the propeller, m representing the parameter I to be identifiedzzC is Nrr。
In performing inertia recognition (i.e. on m)x、myOr IzzFor identification), Xuu、Yvv、NrrUnknown, but Xuu、Yvv、NrrCan be calculated by the following formula
Figure BDA0003073617860000105
Yvv＝-0.5ρ[∫LCD(x)D(x)dx] (15)
Nrr＝Yvv*L3/32 (16)
In the above three formulas, rho is the density of seawater, S is the wet surface area of the ship, L is the length of the ship, and C isD(x) For the resistance coefficient of the cross section of the ship at the coordinate x, 0.7 can be taken for rough estimation. The formula (14) adopts a traditional calculation formula of the resistance of the navigation ship, Rn is Reynolds number, and for dynamic positioning working conditions, the Reynolds number can be 107。
Similarly, when the parameter to be identified is a viscous water kinetic parameter, the method is used for identifying the viscous water kinetic coefficient (i.e. X)uu、Yvv、Nrr) The one-dimensional motion model of (a) is:
Figure BDA0003073617860000111
for equation (17), a one-step transition matrix Φ can be derivedt,t+ΔtIs calculated by the formula
Figure BDA0003073617860000112
Equation (17) is substantially the same as equation (12) except that the parameter to be identified in the state variable is represented by an inertia parameter (m)x、my、Izz) Variable into a viscous water kinetic parameter-Xuu、Yvv、NrrAnd corresponding three degrees of freedom of inertia (m)x、my、Izz) Considered as a known quantity.
When the transverse/longitudinal inertia of the ship and the corresponding viscous hydrodynamic parameters in the transverse or longitudinal direction are identified, the transverse/longitudinal displacement of the ship relative to the seawater can be obtained through GPS measurement, and then the ship can be known
h(a,t)＝s (19)
Ht＝[1 0 0] (20)
When the bow inertia of the ship and corresponding viscous hydrodynamic parameters are identified, the bow of the ship is obtained through a compass, and an observation equation H (a, t) and an observation matrix H of the ship are obtainedtThe same as the formula (19) and the formula (20), respectively.
Illustratively, the step S104 may specifically include:
s1041: and determining the interval time between the current measurement and the last measurement of the measurement system.
Specifically, when measurement data of a GPS or other position reference system is waited, and the measurement time of two adjacent times of a certain data is t and t0, respectively, the interval time is Δ t-t 0.
S1042: and constructing a one-dimensional motion matrix equation corresponding to the parameter to be identified according to the initial value and the current value of the position parameter, the initial value of the speed parameter and the initial value and the current value of the first thrust.
Specifically, when the parameter to be identified is an inertia parameter m, the acquired corresponding parameter can be substituted into an equation (12) to obtain a one-dimensional motion model. Such asWhen the parameter to be identified is the sum m of the ship mass and the longitudinal additional massxIn the process, the longitudinal displacement, the longitudinal speed and the longitudinal first thrust of the ship can be obtained through a measuring system; substituting the longitudinal displacement, the longitudinal speed and the longitudinal first thrust into the formula (12) as s, u and tau in the formula (12) respectivelythruEstablishing a parameter m for identifying inertiaxThe one-dimensional motion model of (1). When the parameter to be identified is the sum m of the ship mass and the transverse additional massyIn the process, the transverse displacement, the transverse speed and the transverse first thrust of the ship can be obtained through the measuring system; the lateral displacement, the lateral velocity and the lateral first thrust are substituted into the formula (12) as s, u and tau in the formula (12)thruEstablishing a parameter m for identifying inertiayThe one-dimensional motion model of (1). When the parameter to be identified is the sum I of the moment of inertia of the ship around the vertical direction and the additional moment of inertiazzIn the process, the heading angular displacement, the heading rotating speed and the first thrust on the heading of the ship can be obtained through the measuring system; substituting the heading angular displacement, the heading rotating speed and the heading first thrust into the formula (12) as s, u and tau in the formula (12) respectivelythruEstablishing parameters I for identifying inertiazzThe one-dimensional motion model of (1).
Similarly, when the parameter to be identified is the viscous water dynamic parameter C, the acquired corresponding parameter may be substituted into the formula (17) to obtain the one-dimensional motion model. Specifically, when the parameter to be identified is the longitudinal quadratic damping coefficient XuuIn the process, the longitudinal displacement, the longitudinal speed and the longitudinal first thrust of the ship can be obtained through a measuring system; substituting the longitudinal displacement, the longitudinal speed and the longitudinal first thrust into the formula (17) as s, u and tau in the formula (17)thruEstablishing a parameter X for identifying the hydrodynamic viscosityuuThe one-dimensional motion model of (1). When the parameter to be identified is the transverse secondary damping coefficient YvvIn the process, the transverse displacement, the transverse speed and the transverse first thrust of the ship can be obtained through the measuring system; substituting the transverse displacement, the transverse speed and the transverse first thrust into the formula (17) as s, u and tau in the formula (17)thruEstablishing a parameter Y for identifying the hydrodynamic viscosityvvThe one-dimensional motion model of (1). When the parameter to be identified is bow turning secondary damping systemNumber NrrIn the process, the heading angular displacement, the heading rotating speed and the first thrust on the heading of the ship can be obtained through the measuring system; substituting the heading angular displacement, the heading rotating speed and the heading first thrust into the formula (17) as s, u and tau in the formula (17) respectivelythruEstablishing a coefficient for identifying hydrodynamic viscosity NrrThe one-dimensional motion model of (1).
S1043: and based on the initial first state vector, performing integral solution on the one-dimensional motion matrix equation to obtain the first state vector at the current moment.
For example, the first state vector and the corresponding first covariance may be set according to the type of the parameter to be identified, and when the parameter to be identified is an inertia parameter, the first state vector is [ s u m [ ]]TWhen the parameter to be identified is a viscous hydrodynamic parameter, the first state vector is [ s u C ]]T. Similarly, the initial first state vector and the corresponding initial first covariance may be set according to the parameter to be identified, for example, when the parameter to be identified is the transverse inertia parameter mxThen, the first state vector a is initializedt0And an initial first covariance Pt0Comprises the following steps:
ato＝[0 0 m0]T
Figure BDA0003073617860000131
wherein m is0Can be taken as the ship mass P11May be taken as 10, P22May be taken as 10, P33May be taken as m0 2。
S1044: and calculating a one-step transfer matrix according to a one-dimensional motion matrix equation, and calculating and obtaining a first covariance corresponding to the first state vector at the current moment based on the one-step transfer matrix and the initial first covariance.
S1045: and observing the first state vector and the corresponding first covariance at the current moment to obtain the observed first state vector and the observed first covariance at the current moment.
Specifically, the first state vector may be calculated according to equations (4), (12) and (17), the one-step transition matrix may be calculated according to equation (6), the first covariance may be calculated according to equation (5), and the observation-corrected first state vector and its corresponding first covariance may be calculated according to equations (7) to (11). It should be noted that the specific calculation process of the above parameters is mentioned in the following embodiments, and therefore, will not be explained in detail here.
After calculating the observed first state vector and the first covariance thereof at the current time, step S105 may specifically include:
judging whether the observed first covariance at the current moment meets a stable condition;
if so, acquiring a parameter to be identified according to the observed first state vector at the current moment;
otherwise, the initial first state vector is updated to the observed first state vector at the current time, the initial first covariance is updated to the observed first covariance at the current time, and the process returns to step S103.
Specifically, the setting of the stable condition may be set according to different parameters to be identified. For example, in one of the embodiments of the present invention. The stability conditions can be set as follows:
observed first covariance
Figure BDA0003073617860000132
After a period of time, the value of (A) begins to oscillate (i.e. the value changes alternately), if at all
Figure BDA0003073617860000133
If the difference between the maximum value and the minimum value of the parameter to be identified does not exceed 50% of the average value thereof within a certain time (for example, 5 minutes) of the continuous oscillation, it is considered that a stable condition is reached, and the average value is taken as the final identification result of the parameter to be identified. Specifically, the average value and the maximum and minimum values of the parameter to be identified may be calculated as follows: obtaining the numerical value of the parameter to be identified corresponding to each measurement according to the observed first state vector obtained by each calculation, and calculating each parameter to be identifiedThe average value of the numerical values of the other parameters, and the maximum value and the minimum value of each parameter to be identified are determined.
The meaning of covariance is to represent the uncertainty of the state variables. That is, if the first covariance satisfies a certain stable condition, the first state vector can be approximately considered to tend to be determined, and therefore, the parameter to be identified can be determined according to the first state vector at that time.
On the other hand, if the observed first covariance does not satisfy the stable condition, it indicates that the observed first state vector at this time cannot be approximately determined, and therefore cannot be used as a basis for the parameter to be identified, an iterative method needs to be used to continuously calculate the observed first state vector at the next time to update the current first state vector, and calculate the covariance corresponding to the updated state vector, and then whether the covariance corresponding to the updated first state vector satisfies the stable condition is judged, if so, the group acquires the parameter to be identified according to the updated first state vector, otherwise, the iterative calculation is continued until the covariance satisfies the stable condition. Specifically, in the iterative calculation process, if it is determined that the covariance corresponding to the observed first state vector at the current time does not satisfy the stability condition, the observed first state vector at the current time may be used as the initial state vector, and the step S1043 is returned to perform calculation to obtain the observed first state vector at the next time.
The following identification process of each inertia parameter and each viscous hydrodynamic parameter is specifically described with reference to the embodiments.
Examples
For the sum m of the ship mass and the longitudinal additional massxTransverse secondary damping coefficient XuuThe identification process of (2):
step 1: calibration of ship flow velocity and direction
The dynamic positioning control system which is deployed but has not accurately estimated parameters is adopted, the operation mode of the target ship is set as automatic heading, the position is freely controlled by adopting a handle, and the operation handle of the dynamic positioning control system is operated to a zero position to push the shipThe propeller keeps the heading direction and simultaneously generates zero thrust in the transverse direction and the longitudinal direction, and the longitudinal speed and the transverse speed of the ship are recorded as the longitudinal flow velocity u of the ocean current after keeping the state for 20 minutescAnd the cross flow velocity v of the ocean currentc。
Step 2: setting initial state of inertia identification filter
Record the current time as t0 and let tinitRecording the north position N of the ship in the northeast dynamic coordinate system at the moment t0initEast position EinitAnd heading HdinitSetting the initial state of the filter (i.e. the initial first state vector a)t0And its corresponding initial first covariance Pt0)
ato＝[0 0 m0]T
Figure BDA0003073617860000141
Wherein m is0Can be taken as the ship mass P11May be taken as 10, P22May be taken as 10, P33May be taken as m0 2。
Setting filter parameters
Figure BDA0003073617860000142
R＝[Rpos]
Wherein Q iswuIs represented by the formula (12) wuCovariance, Q, of this uncertain disturbance variablewmIs wmOf (2) covariance, RposI.e. the degree of inaccuracy of the position observation, i.e. the observation variance, e.g. when RposTaking 0.25, the error of the position measurement can be considered to be substantially 0.5 m. In particular, the amount of the solvent to be used,
Figure BDA0003073617860000157
it may be desirable to have a value of 0.01,
Figure BDA0003073617860000158
is taken to be 0.0001m0 2，RposMay be taken to be 0.25.
And step 3: identification mx
This step is performed in two ways, which are performed simultaneously, i.e. in step 3.1 and step 3.2 as follows.
Step 3.1
The operation handle of the dynamic positioning control system is adopted to continuously and alternately operate forwards and backwards, so that the longitudinal speed of the ship and the longitudinal flow velocity u of ocean currentcThe difference of (a) varies rapidly between positive and negative values, during which the thrust exerted by all the thrusters on the hull undergoes a real-time calculation from the values measured by the relative sensors.
Step 3.2, specifically comprising the following substeps
Step 3.2.1: waiting for the measurement data of GPS or other position reference system, and calculating the time interval assuming the measurement time of certain data is t
Δt＝t-t0
Step 3.2.2: calculating a new first state vector a based on the formula expressed by the formula (12) and the formula (4) and the formula (5) and the longitudinal thrust applied to the hull by the propellertAnd its corresponding first covariance Pt。
Step 3.2.3: calculating the absolute northeast coordinate of the GPS from the measured data, and recording as Nt，EtAnd calculating an observed value by using the two values:
b＝(Nt-Ninit)*cos(Hdinit)+(Et-Einit)*sin(Hdinit)-uc(t-tinit)
step 3.2.4: the first state vector after observation at the current time is calculated from the expressions (19) and (20) and the expressions represented by the expressions (8), (9) and (10)
Figure BDA0003073617860000151
And its corresponding first covariance
Figure BDA0003073617860000152
Observe firstCovariance
Figure BDA0003073617860000153
Whether or not to tend to be stable, if so, m is finishedxAnd m isxIs prepared by
Figure BDA0003073617860000154
A third component; otherwise let t0 equal t, at0Is equal to
Figure BDA0003073617860000155
Pt0Is equal to
Figure BDA0003073617860000156
And returning to execute the step 3.2.1, continuously waiting for new GPS measurement data, and sequentially executing the step 3.2.2 to the step 3.2.4 according to the new measurement data.
And 4, step 4: setting an initial state of a filter for identifying viscous hydrodynamic parameters:
recording the current time as t0, and recording the north position N of the ship at the timeinitEast position EinitAnd heading HdinitSetting the initial state of the filter (i.e., the initial first state direction and its corresponding initial first covariance)
ato＝[0 0 Cuu0]T
Figure BDA0003073617860000161
Wherein C isuu0Can be obtained by rough estimation calculation according to equation (16), P11May be taken as 10, P22May be taken as 10, P33Can be taken as Cuu0 2。
Setting filter parameters
Figure BDA0003073617860000162
R＝[Rpos]
Figure BDA0003073617860000169
It may be desirable to have a value of 0.01,
Figure BDA00030736178600001610
is taken to be 0.0001Cuu0 2，RposMay be taken to be 0.25.
And 5: identification of Xuu
Like step 3, this step also works in both ways, i.e. simultaneously with step 5.1 and step 5.2 as follows.
Step 5.1: a longitudinal fixed value is given by an operating handle of a dynamic positioning control system, so that the ship propulsion system maintains a certain thrust force in the longitudinal direction. In the process, the thrust applied to the ship body by all the propellers is calculated in real time by the measured values of the related sensors.
Step 5.2, which consists of
Step 5.2.1: waiting for GPS or other position reference system measurement data, and calculating time interval assuming the measurement time of the data is t
Δt＝t-t0
Step 5.2.2: calculating a new first state vector a according to equation (17) using the equations expressed by equations (4) and (5) and the longitudinal thrust applied to the hull by the propellertAnd its corresponding first covariance Pt。
Step 5.2.3: calculating the absolute northeast coordinate of the GPS from the measured data, and recording as Nt，EtAnd calculating an observed value by using the two values:
b＝(Nt-Ninit)*cos(Hdinit)+(Et-Einit)*sin(Hdinit)-vc(t-tinit)
step 5.2.4: the first state vector after observation at the current time is calculated using the formulas expressed by formulas (8), (9) and (10) based on formulas (19) and (20)
Figure BDA0003073617860000164
And its corresponding first covariance
Figure BDA0003073617860000163
Observing the first covariance
Figure BDA0003073617860000165
Whether or not to tend to be stable, if so, completing XuuIdentification of (1), XuuIs that
Figure BDA0003073617860000166
The third component of (a); otherwise let t0 equal t, at0Is equal to
Figure BDA0003073617860000167
Pt0Is equal to
Figure BDA0003073617860000168
And returning to execute the step 5.2.1, continuously waiting for new GPS measurement data, and sequentially executing the step 5.2.2 to the step 5.2.4 according to the new measurement data.
Second, regarding the sum m of the ship mass and the transverse additional massyTransverse secondary damping coefficient YvvThe identification process of (2):
myand YvvThe specific steps of identification and the identification m involved in the first embodimentxAnd XuuThe specific steps of (A) are similar and can be at XuuThe identification is performed continuously after completion. The method comprises the following specific steps:
step 6: and mx、XuuStep 2 in the identification process is the same, and is not described herein again.
Of course, for myAnd YvvCan also be performed separately or on mx、XuuBefore the identification is performed, in this case, m needs to be executed and identified firstx、XuuAfter the same step as step 1 in the process, step 6 is performed. Namely, before step 6, the calibration of the flow speed and the flow direction of the ship is needed firstly, a deployed dynamic positioning control system which does not accurately estimate parameters is adopted, and the operation mode of the target ship is set as the heading automaticThe position is freely controlled by a handle, an operating handle of the dynamic positioning control system is operated to a zero position, so that the thrust generated by the ship propeller in the transverse direction and the longitudinal direction is zero while the ship propeller keeps heading, and the longitudinal speed and the transverse speed of the ship are recorded as the longitudinal flow velocity u of ocean current after the ship propeller keeps the state for 20 minutescAnd the cross flow velocity v of the ocean currentc。
And 7: identification myStep 7 is similar to step 3, and specifically comprises the following steps:
step 7.1: the operation handle of the dynamic positioning control system is adopted to continuously and alternately operate leftwards and rightwards, so that the transverse speed of the ship and the transverse flow velocity v of ocean currentcThe difference of (a) varies rapidly between a positive value and a negative value, during which the thrust exerted by all the thrusters on the hull is calculated in real time from the values measured by the relative sensors.
Step 7.2: divide b value calculation formula and calculate new
Figure BDA0003073617860000171
The thrust used is the same as in step 3.2 except that the thrust is the transverse force applied to the hull by the propeller. The formula for calculating the b value in this step is as follows:
b＝-(Nt-Ninit)*sin(Hdinit)+(Et-Einit)*cos(Hdinit)
and 8: except for Cuu0The operation is the same as that of step 4 except that the initial value of (2) is roughly calculated by equation (15).
Step 9, identify YvvThe steps are similar to the step 5, and specifically comprise:
step 9.1: a transverse fixed value is given by an operating handle of a dynamic positioning control system, so that the ship can maintain a certain thrust in the transverse direction. The thrust exerted by all the thrusters on the hull during this process is subject to values measured by the relevant sensors.
Step 9.2: the calculation of the b value is the same as in step 7.2, where the b value is calculated and a new value is calculated
Figure BDA0003073617860000172
The rest of the operation is the same as step 5.2 except that the thrust is the transverse force applied to the ship body by the propeller, and therefore, the description is omitted.
Third, the sum I of the moment of inertia of the ship around the z' axis and the additional moment of inertiazzSecondary damping coefficient N of bow turningrrThe identification process of (2):
step 1: the ship floats freely for 20 minutes
Step 2: setting an initial state of the inertia identification filter, specifically as follows:
recording the current time as t0, and recording the heading Hd of the ship at the momentinitSetting the initial state of the filter (i.e., the initial first state vector and its corresponding initial first covariance)
ato＝[0 0 m0]T
Figure BDA0003073617860000181
Wherein m is0Can be taken as the ship inertia moment, P11May be taken as 10, P22May be 1, P33It may be desirable that the thickness is 0.0001m0。
Setting filter parameters
Figure BDA0003073617860000182
R＝[Rpos]
As mentioned in the foregoing description,
Figure BDA0003073617860000185
is represented by the formula (12) wuThis uncertainty interferes with the covariance of the variables,
Figure BDA0003073617860000184
is wmOf (2) covariance, RposNamely the inaccuracy degree of the position observation quantity, namely the observation variance. In the process of the identification at this time,
Figure BDA0003073617860000183
it may be desirable to have a value of 0.01,
Figure BDA0003073617860000186
is taken to be 0.0001m0 2，RposMay be taken as 0.000076.
And step 3: identification Izz
This step is done in two ways, which are done simultaneously, step 3.1 and step 3.2 as follows.
Step 3.1
The dynamic positioning control system is adopted to operate the handle to continuously and alternately rotate the bow clockwise and anticlockwise, so that the bow rotating speed of the ship is alternately changed between positive and negative, and the thrust applied to the ship body by all the propellers in the process is measured by the relevant sensors and calculated in real time.
Step 3.2 this substep consists of
3.2.1 waiting for heading signals measured by the electric compass, assuming a certain heading measurement data HdtIs t, calculating the time interval
Δt＝t-t0
3.2.2 calculating a new first state vector a according to the formulas expressed by the formulas (12), (4) and (5) and the heading moment applied to the hull by the propellertAnd its corresponding first covariance Pt。
3.2.3 calculating observations from measurement data
b＝Hdt-Hdinit
3.2.4 calculating the first state vector after observation at the current time using the expressions represented by expressions (8), (9) and (10) based on expressions (19) and (20)
Figure BDA0003073617860000194
And its corresponding first covariance
Figure BDA0003073617860000195
Observing the first covariance
Figure BDA0003073617860000193
Whether or not to tend to be stable, if so, completing IzzIdentification of (I)zzIs composed of
Figure BDA0003073617860000196
The third component of (a); otherwise let t0 equal t, at0Is equal to
Figure BDA0003073617860000197
Pt0Is equal to
Figure BDA0003073617860000198
And returning to execute the step 3.2.1, continuously waiting for new electric compass measurement data, and sequentially executing the step 3.2.2 to the step 3.2.4 according to the new measurement data.
And 4, step 4: setting an initial state of a filter for identifying viscous hydrodynamic parameters:
recording the current time as t0, and recording the heading Hd of the ship at the momentinitSetting the initial state of the filter (i.e., the initial first state direction and its corresponding initial first covariance)
ato＝[0 0 Cuu0]T
Figure BDA0003073617860000191
Wherein C isuu0Can be roughly estimated according to the formula (16), P11May be taken as 10, P22May be taken as 10, P33May be preferably 0.0001Cuu0 2。
Setting filter parameters
Figure BDA0003073617860000192
R＝[Rpos]
Figure BDA0003073617860000199
It may be desirable to have a value of 0.01,
Figure BDA00030736178600001910
is taken to be 0.0001Cuu0 2，RposMay be taken as 0.000076.
And 5: identification of Nrr
Similar to step 3 in the present identification process, this step also performs two operations, which are performed simultaneously, i.e. step 5.1 and step 5.2 as follows.
Step 5.1
A constant heading turning instruction is given by an operating handle of a dynamic positioning control system, so that a certain heading turning moment is maintained in the longitudinal direction of the ship. In the process, the thrust exerted on the ship body by all the propellers is calculated in real time by the measured values of the related sensors
Step 5.2 this substep consists of
5.2.1 waiting for heading signals measured by the electric compass, assuming a certain heading measurement data HdtIs t, calculating the time interval
Δt＝t-t0
5.2.2 calculating a new first state vector a according to equation (17) using the equations expressed by equations (4) and (5) and the heading moment applied to the hull by the propellertAnd its corresponding first covariance Pt。
5.2.3 calculating observations from measurement data
b＝Hdt-Hdinit
5.2.4 calculating the first state vector after observation at the current time using the expressions represented by expressions (8), (9) and (10) based on expressions (19) and (20)
Figure BDA0003073617860000202
And its corresponding first covariance
Figure BDA0003073617860000201
Observing the first covariance
Figure BDA0003073617860000203
Whether the stability is trend or not, if so, completing NrrIdentification of (N)rrIs composed of
Figure BDA0003073617860000204
The third component of (a); otherwise let t0 equal t, at0Is equal to
Figure BDA0003073617860000205
Pt0Is equal to
Figure BDA0003073617860000206
And returning to execute the step 5.2.1, continuously waiting for new electric compass measurement data, and sequentially executing the step 5.2.2 to the step 5.2.4 according to the new measurement data.
The parameter identification method provided by the invention can effectively identify the key parameters (including inertia parameters and viscous water dynamic parameters) in the ship motion model of the dynamic positioning ship control system filter, has no special requirements on the test environment in the implementation process, does not need extra early-stage calculation, and is simple and easy to operate.
Accordingly, the embodiment of the present invention also provides a computer-readable storage medium, which stores instructions that, when executed on a computer, can cause the computer to execute the parameter identification method.
Referring to FIG. 3, shown is a block diagram of an electronic device 400 in accordance with one embodiment of the present application. The electronic device 400 may include one or more processors 401 coupled to a controller hub 403. For at least one embodiment, the controller hub 403 communicates with the processor 401 via a multi-drop Bus such as a Front Side Bus (FSB), a point-to-point interface such as a QuickPath Interconnect (QPI), or similar connection port. Processor 401 executes instructions that control general types of data processing operations. In one embodiment, the Controller Hub 403 includes, but is not limited to, a Graphics Memory Controller Hub (GMCH) (not shown) and an Input/Output Hub (IOH) (which may be on separate chips) (not shown), where the GMCH includes a Memory and a Graphics Controller and is coupled to the IOH.
The electronic device 400 may also include a coprocessor 402 and memory 404 coupled to the controller hub 403. Alternatively, one or both of the memory and GMCH may be integrated within the processor (as described herein), with the memory 404 and coprocessor 402 coupled directly to the processor 401 and controller hub 403, with the controller hub 403 and IOH in a single chip.
The Memory 404 may be, for example, a Dynamic Random Access Memory (DRAM), a Phase Change Memory (PCM), or a combination of the two. Memory 404 may include one or more tangible, non-transitory computer-readable media for storing data and/or instructions therein. A computer-readable storage medium has stored therein instructions, and in particular, temporary and permanent copies of the instructions. The instructions may include: instructions that, when executed by at least one of the processors, cause the electronic device 400 to implement a method as shown in fig. 1 or fig. 2. The instructions, when executed on a computer, cause the computer to perform the methods disclosed in any one or combination of the embodiments above.
In one embodiment, the coprocessor 402 is a special-purpose processor, such as, for example, a high-throughput MIC (man Integrated Core) processor, a network or communication processor, compression engine, graphics processor, GPGPU (General-purpose computing on graphics processing unit), embedded processor, or the like. The optional nature of coprocessor 402 is represented in FIG. 3 by dashed lines.
In one embodiment, the electronic device 400 may further include a Network Interface Controller (NIC) 406. Network interface 406 may include a transceiver to provide a radio interface for electronic device 400 to communicate with any other suitable device (e.g., front end module, antenna, etc.). In various embodiments, the network interface 406 may be integrated with other components of the electronic device 400. The network interface 406 may implement the functions of the communication unit in the above-described embodiments.
The electronic device 400 may further include an Input/Output (I/O) device 405. I/O405 may include: a user interface designed to enable a user to interact with the electronic device 400; the design of the peripheral component interface enables peripheral components to also interact with the electronic device 400; and/or sensors are designed to determine environmental conditions and/or location information corresponding to electronic device 400.
It is noted that fig. 3 is merely exemplary. That is, although fig. 3 shows that the electronic device 400 includes a plurality of devices, such as a processor 401, a controller hub 403, a memory 404, etc., in practical applications, the device using the methods of the present application may include only a part of the devices of the electronic device 400, for example, may include only the processor 401 and the network interface 406. The nature of the optional device in fig. 3 is shown in dashed lines.
Referring now to fig. 4, shown is a block diagram of a SoC (System on Chip) 500 in accordance with an embodiment of the present application. In fig. 4, similar components have the same reference numerals. In addition, the dashed box is an optional feature of more advanced socs. In fig. 4, SoC500 includes: an interconnect unit 550 coupled to the processor 510; a system agent unit 580; a bus controller unit 590; an integrated memory controller unit 540; a set or one or more coprocessors 520 which may include integrated graphics logic, an image processor, an audio processor, and a video processor; a Static Random-Access Memory (SRAM) unit 530; a Direct Memory Access (DMA) unit 560. In one embodiment, coprocessor 520 comprises a special-purpose processor, such as, for example, a network or communication processor, compression engine, GPGPU (General-purpose computing on graphics processing units, General-purpose computing on a graphics processing unit), high-throughput MIC processor or embedded processor, or the like.
Static Random Access Memory (SRAM) unit 530 may include one or more tangible, non-transitory computer-readable media for storing data and/or instructions. A computer-readable storage medium has stored therein instructions, and in particular, temporary and permanent copies of the instructions. The instructions may include: instructions that when executed by at least one of the processors cause the SoC to implement the method as shown in fig. 1 or fig. 2. The instructions, when executed on a computer, cause the computer to perform the methods disclosed in the embodiments described above.
The method embodiments of the present application may be implemented in software, magnetic, firmware, etc.
Program code may be applied to input instructions to perform the functions described herein and generate output information. The output information may be applied to one or more output devices in a known manner. For purposes of this application, a processing system includes any system having a Processor such as, for example, a Digital Signal Processor (DSP), a microcontroller, an Application Specific Integrated Circuit (ASIC), or a microprocessor.
The program code may be implemented in a high level procedural or object oriented programming language to communicate with a processing system. The program code can also be implemented in assembly or machine language, if desired. Indeed, the mechanisms described herein are not limited in scope to any particular programming language. In any case, the language may be a compiled or interpreted language.
One or more aspects of at least one embodiment may be implemented by representative instructions stored on a computer-readable storage medium, which represent various logic in a processor, which when read by a machine causes the machine to fabricate logic to perform the techniques herein. These representations, known as "IP (Intellectual Property) cores," may be stored on a tangible computer-readable storage medium and provided to a number of customers or production facilities to load into the manufacturing machines that actually manufacture the logic or processors.
In some cases, an instruction converter may be used to convert instructions from a source instruction set to a target instruction set. For example, the instruction converter may transform (e.g., using a static binary transform, a dynamic binary transform including dynamic compilation), morph, emulate, or otherwise convert the instruction into one or more other instructions to be processed by the core. The instruction converter may be implemented in software, hardware, firmware, or a combination thereof. The instruction converter may be on the processor, off-processor, or partially on and partially off-processor.
While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing is a more detailed description of the invention, taken in conjunction with the specific embodiments thereof, and that no limitation of the invention is intended thereby. Various changes in form and detail, including simple deductions or substitutions, may be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims (10)

1. A parameter identification method is used for a ship dynamic positioning control system filter, and is characterized by comprising the following steps:
s101: after the ship is in a preset state, receiving an initial value of a position parameter, an initial value of a speed parameter and an initial value of a first thrust provided to the ship by a propulsion system, wherein the initial values of the position parameter and the speed parameter are measured by a measurement system at an initial moment, the initial values of the position parameter and the speed parameter correspond to parameters to be identified, the initial values of the first thrust are provided to the ship by the propulsion system, a filter of the ship is set to be in an initial state, and initial filtering parameters are set;
s102: adjusting an operating handle of a dynamic positioning control system to place the vessel in a first state;
s103: receiving the current value of the position parameter and the current value of the first thrust corresponding to the parameter to be identified, which are measured by a measurement system at the current moment;
s104: according to the received initial value and current value of the position parameter, the initial value of the speed parameter and the initial value and current value of the first thrust, constructing a motion model corresponding to the parameter to be identified, and according to the motion model and the initial filter parameter, calculating an observed first state vector at the current moment and an observed first covariance corresponding to the observed first state vector;
s105: judging whether the observed first covariance meets a stable condition;
if so, acquiring the parameter to be identified according to the observed first state vector;
otherwise, return to execute S103.
2. The parameter identification method of claim 1, wherein the initial filter parameters comprise an initial first state vector and an initial first covariance to which the initial first state vector corresponds.
3. The parameter identification method according to claim 2, wherein step S104 comprises:
determining the interval time between the current measurement and the last measurement of the measurement system;
constructing a one-dimensional motion matrix equation corresponding to the parameter to be identified according to the initial value and the current value of the position parameter, the initial value of the speed parameter and the initial value and the current value of the first thrust;
based on the initial first state vector, performing integral solution on the one-dimensional motion matrix equation to obtain a first state vector at the current moment;
calculating a one-step transfer matrix according to the one-dimensional motion matrix equation, and calculating and obtaining a first covariance corresponding to a first state vector at the current moment based on the one-step transfer matrix and the initial first covariance;
and observing the first state vector and the corresponding first covariance at the current moment to obtain the observed first state vector and the observed first covariance at the current moment.
4. The parameter identification method according to claim 3, wherein step S105 comprises:
judging whether the observed first covariance at the current moment meets a stable condition;
if so, acquiring the parameter to be identified according to the observed first state vector at the current moment;
otherwise, updating the initial first state vector to the observed first state vector at the current time, updating the initial first covariance to the observed first covariance at the current time, and returning to execute S103.
5. The parameter identification method of claim 3, wherein the one-dimensional motion matrix equation is:
Figure FDA0003073617850000021
wherein s is a position parameter corresponding to the parameter to be identified, u is a speed parameter corresponding to the parameter to be identified, X is the parameter to be identified, and tauthruProviding a first thrust corresponding to the parameter to be identified to the vessel for a propulsion system, m being an inertia parameter, C being a viscous hydrodynamic parameter, WuFor uncertainty interference of kinetic equations, WXIs the uncertainty interference of the parameter to be identified.
6. The parameter identification method according to claim 1, wherein the parameter to be identified comprises an inertia parameter to be identified and a viscous water dynamic parameter to be identified;
when the parameter to be identified is the inertia parameter to be identified, step S102 includes:
controlling the operating handle to continuously and alternately operate so that the difference value between the speed parameter corresponding to the inertia parameter to be identified and the ocean current speed corresponding to the inertia parameter to be identified is changed alternately between a positive value and a negative value;
when the parameter to be identified is the viscous water kinetic parameter to be identified, step S102 includes:
adjusting the operating handle to maintain a thrust of a propulsion system of the vessel in a corresponding direction.
7. The parameter identification method of claim 6,
when the inertia parameter to be identified is the sum of the ship mass and the transverse or longitudinal additional mass, and/or the viscous hydrodynamic parameter to be identified is a transverse or longitudinal secondary damping coefficient, the preset state in step S101 is that the operating handle of the dynamic positioning control system is maintained at the zero position for a first preset time; before step S101, the parameter identification method further includes:
setting the operation mode of the ship to be heading automatic, adjusting an operation handle of the dynamic positioning control system to a zero position so that the thrust generated by the ship in the transverse direction and the longitudinal direction is zero while the ship propulsion system keeps heading, and keeping the operation handle at the zero position for the first preset time;
when the inertia parameter to be identified is the sum of the moment of inertia of the ship around the vertical direction and the additional moment of inertia, and/or the viscous hydrodynamic parameter to be identified is a secondary yaw damping coefficient, the preset state in step S101 is that the ship floats freely for a second preset time.
8. The parameter identification method according to claim 7, wherein the first preset time and/or the second preset time is 20 min.
9. The parameter identification method of claim 7,
when the parameter to be identified is the sum of the ship mass and the longitudinal additional mass, and/or the viscous hydrodynamic parameter to be identified is the longitudinal secondary damping coefficient, the speed parameter is the longitudinal flow velocity of the ship, the position parameter is the longitudinal displacement of the ship, and the first thrust is the longitudinal thrust provided by the propulsion system to the ship;
when the parameter to be identified is the sum of the ship mass and the transverse additional mass, and/or the viscous hydrodynamic parameter to be identified is a transverse secondary damping coefficient, the speed parameter is a transverse flow velocity of the ship, the position parameter is a transverse displacement of the ship, and the first thrust is a transverse thrust provided by the propulsion system to the ship;
when the parameter to be identified is the sum of the moment of inertia of the ship around the vertical direction and the additional moment of inertia and/or the viscous hydrodynamic parameter to be identified is a secondary yaw damping coefficient, the speed parameter is the yaw rotating speed of the ship, the position parameter is the yaw angular displacement of the ship, and the first thrust is the yaw moment provided by the propulsion system to the ship.
10. A computer-readable storage medium having stored thereon instructions that, when executed on a computer, cause the computer to perform the parameter identification method of any one of claims 1-9.
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