Method of defining ship mathematical model hydrodynamic parameters

FIELD: transport.

SUBSTANCE: invention relates to navigation and can be used for forecasting ship manoeuvres. Proposed method comprises application of ship motion mathematical model and two fore and aft points F and A points, respectively, spaced apart over the centre plane length, Defining current coordinates of ship motion kinematic parameters in moving coordinate system ZX0Y to define current hydrodynamic parameters of ship mathematical model and to execute computer simulation of the basis of the latter. Moving coordinate system ZX0Y is related to the ship. Acceleration transducers are used to define in real time the current magnitudes of lengthwise, crosswise and angular accelerations of fore and aft points F (w_fx1, W_fy1, ε) and A (w_ax1, W_ay1, ε) in fixed coordinate system X₁0₁Y₁. Said magnitudes are used to define current magnitudes of ship motion kinematic parameters.

EFFECT: higher accuracy of forecast.

2 cl, 1 dwg

The invention relates to the field of navigation and can be used to predict the motion of a vessel at high speed.

There is a method of determining the hydrodynamic parameters of the mathematical model of the vessel (U.S. Pat. Of the Russian Federation No. 2442718, publ. 20.02.2012), based on the measurement using a satellite navigation system with differential corrections in real time coordinates of the two in a certain way posted in the median plane along the length of the vessel points, conventionally called the bow and stern, and determining, using the measurement data of the current coordinates of these points, the current values of the kinematic parameters of the movement of the ship:

linear velocities of the nasal F (υ_fand aft A (υ_apoints and their projections on the longitudinal X (υ_xf, υ_ha) and transverse Y (υ_yf, υ_ya) coordinate axes of the moving coordinate system ZXY associated with the vessel;

the abscissa of the center of rotation (x_about) in the coordinate system ZXY;

projection of the vector of linear velocity at the center of gravity on the transverse axis Y (υ_y);

- the linear velocity of the center of gravity of the vessel (υ);

the radius of curvature of the trajectory of the CG of the vessel (R);

angular speed (ω),

which is used to calculate the current values of the hydrodynamic parameters of the mathematical model of the vessel, on the basis of which the Oh perform computer modeling to predict the motion of a vessel at high speed. This method is most similar to that proposed and adopted for the prototype.

The disadvantage of this method is that to determine the kinematic parameters of the movement of the vessel is necessary to resort to numerical differentiation parameters, measured using a satellite navigation system, which reduces the accuracy of the results of the calculation of kinematic parameters of the movement of the vessel. This disadvantage becomes more significant if the accuracy of the bow and stern points of the vessel for any reason (weather, navigation area, and others) is reduced.

The aim of the proposed method is an exception noted shortage when the calculation-experimental determination of parameters of the mathematical model of the vessel in a continuous mode and, consequently, increase the accuracy of predicting the motion of the ship in the execution of his maneuvering using computer simulation on the basis of an adequate mathematical model of the vessel.

The technical result, which is aimed by the invention is to improve the accuracy of predicting the motion of the ship in the execution of his maneuvering.

To achieve the technical result in the method for determining the hydrodynamic parameters of the mathematical model of the vessel, including the COI is whether the mathematical model of the motion of the ship, two spaced apart along the length of the median plane of the ship points fore F and feed A, determine the current values of the kinematic parameters of the movement of the vessel in the moving coordinate system ZXY associated with the vessel, and on their basis of calculation of current hydrodynamic parameters of the mathematical model of ship motion, computer simulation of ship motion on the basis of the latter, using the acceleration sensors, with their help, determine in real time the current values of the longitudinal, transverse and angular accelerations of the nasal F (w_fx1, w_fy1, ε) and feed A (w_ax1, w_ay1, ε) points in the fixed coordinate system X₁O₁Y₁on this basis determine the current values of the kinematic parameters of movement of a vessel.

The proposed method is illustrated by a drawing.

The method consists in the following. A mathematical model of the vessel used for computer modeling in forecasting the movement of the vessel in the process of maneuvering, is a system of differential equations, the General view which, given the known conventions[1], [2], [3], [4], [5], the following:

where υ_x, υ_yprojection of the vector of linear velocity at the CG of the vessel in the longitudinal OH and cross shelter axis, respectively;

ψ - direction of the vessel;

X₁, Y₁- CG coordinate vessel in the fixed coordinate system X₁About₁Y₁;

C₁With₂With₃, ... the parameters of the mathematical model, the numerical values are determined from the geometrical elements of the immersed part of the hull, which is constant when the load status of the last[1], [2], [3], [4], [5].

In the process of ship motion using accelerometers to determine the longitudinal, transverse and the corner speed up the nasal F(w _fx1, w_fy1, ε) and feed A (w_ax1, w_ay1, ε) points of the vessel in the fixed coordinate system X₁About₁Y₁and calculated longitudinal and transverse components of the linear velocity of the bow (υ_fx1, υ_fy1) and aft (υ_ax1, υ_ay1points with known dependencies:

Next, calculate the longitudinal and transverse components of the linear velocity of the nasal F (υ_fx, υ_fyand aft A (υ_ax, υ_aypoints of the vessel in the moving coordinate system ZXY associated with the vessel is a net impact on the vessel during maneuvering:

where υ_st- flow rate;

q_st- the direction of flow.

It is obvious that the longitudinal component of the linear velocity of the vessel at any given point, located on the APS will have one value, so we may assume that

Using the values of the abscissa of the nasal point F in the coordinate system ZXY (x_f) and the abscissa feed point A in the same coordinate system (x_a), as well as transverse components of the linear velocity in the forward (υ_fy) and aft (υ_ay) points identified using dependency (3), calculate the x-coordinate of the center of rotation of the vessel (see drawing) x_o[1], [2], [3], [4], [5] according to the formula:

$$x_o=({\upsilon }_{ay}{x}_f+{\upsilon }_{fy}{x}_a/\left({\upsilon }_{fy}+{\upsilon }_{ay}\right).\left(5\right)$$

The transverse component of the linear velocity at the CG of the vessel is determined by the formula obtained by drawing, namely:

$${\upsilon }_y=\left[{\upsilon }_{fy}\right]/\left(x_f-x_o\right).\left(6\right)$$

The angular velocity of the ship

$$\omega ={\displaystyle \int \epsilon \left(t\right)dt\left(7\right)}$$

The current values of the coefficients C₁C₂C₃, ... count depending on the geometric elements of the immersed part of the hull, which is constant when the load status of the last[1], [2], [3], [4], [5].

So, determine all hydrodynamic parameters of the mathematical model of the vessel, included in the right hand sides of the differential equations (1). By calculating the right side of equations (1), at any given point in time to calculate the values of the parameters characterizing the movement of the vessel while performing the maneuver, namely υ_x, υ_y, ω, ψ, X₁, Y₁that allows us to predict any maneuver to implementation using the methods of computer simulation.

Literature

1. Bassin A.M. Propulsion and handling of ships / A.M. basin. - M.

2. Vasiliev A.V. Controllability of the courts: textbook. manual / Avecilla. - Leningrad: Sudostroenie, 1989. - 328 S.

3. Hoffman A.D. Propulsion and steering complex and maneiro is the use of vessel: directory / A.D. Hoffman. - Leningrad: Sudostroenie, 1988. - 360 C.

4. Sobolev, GV Handling of ship automation and navigation / GV Sobolev. - Leningrad: Sudostroenie, 1976. - 478 S.

5. A guide to theory of the ship. 3 so Vol.3: the Controllability of the displacement vessels. Hydrodynamics of vessels with dynamic-support / under the editorship of YA Waitmessage. - Leningrad: Sudostroenie, 1985. - 544 S.

1. The way to determine hydrodynamic parameters of the mathematical model of the vessel, including the use of a mathematical model of the motion of the ship, two spaced apart along the length of the median plane of the ship points fore F and feed A, determine the current values of the kinematic parameters of the movement of the vessel in the moving coordinate system ZXY associated with the vessel, and on their basis of calculation of current hydrodynamic parameters of the mathematical model of ship motion, computer simulation of ship motion on the basis of the latter, characterized in that the use of acceleration sensors, with their help, determine in real time the current values of the longitudinal, transverse and angular accelerations of the nasal F (w_fx1, w_fy1, ε) and feed A (w_ax1, w_ay1, ε) points in the fixed coordinate system X₁About₁Y₁on this basis determine the current values of the kinematic parameters of movement of a vessel.

2. The method according to claim 1, characterized in that it determines, after the respective values of the kinematic parameters:
- the linear velocity of the nasal F (υ_fand aft A (υ_apoints and their projections on the longitudinal OH (υ_xf, υ_xaand cross-OS (υ_yf, υ_ya) coordinate axes of the moving coordinate system ZXY associated with the vessel;
the abscissa of the center of rotation (x_about) in the moving coordinate system ZXY;
projection of the vector of linear velocity at the center of gravity on the transverse axis of the shelter (υ_y);
- angular speed of the vessel (ω).