KR102154545B1 - Device and Method for Designing Environment-Adaptive Flight Model for Underwater Glider, Recording Medium for Performing the Method - Google Patents

Abstract

The present invention relates to an apparatus and method for designing an environmentally adaptive flight model of an underwater glider capable of obtaining a highly accurate flight model according to the physical characteristics of the underwater glider and environmental characteristics of the ocean, and to a recording medium for performing the method, and a flight model Setting basic parameters of; Calculating the vertical speed of the underwater glider; Setting initial conditions of flight parameters; Calculating the entry angle of the underwater glider through numerical computation; Calculating a vertical speed from the flight model; And determining the flight parameters as final flight parameters of the flight model.

Description

Device and Method for Designing Environment-Adaptive Flight Model for Underwater Glider, Recording Medium for Performing the Method

The present invention relates to an apparatus and method for designing an environmentally adaptive flight model of an underwater glider, and to a recording medium for performing the method, and more particularly, to obtain a highly accurate flight model according to the physical characteristics of the underwater glider and the environmental characteristics of the ocean. It relates to an apparatus and method for designing an environmentally adaptive flight model of an underwater glider, and a recording medium for performing the method.

In general, the Underwater Glider is an unmanned marine exploration robot designed to move to a desired point while moving between the deep and surface layers of the sea. Since it does not use the propellant of the vehicle, it is more efficient than unmanned diving information in terms of energy.

The propulsion force of these underwater gliders is generated by controlling the buoyancy by the inflow and outflow of fluid and the moment change using the movement of the internal mass and the wing. Therefore, the underwater glider uses relatively little power energy, so it is suitable for long and long-distance marine exploration.

Conventional conventional underwater gliders include a body manufactured to withstand deep water pressure, fixed wings provided on both sides of the body, a rudder (or elevator) provided at the rear end of the body, and buoyancy provided inside the body. It includes a tank, a pump connected to the buoyancy tank, a control unit for controlling the rudder and the pump, and a battery connected to the fisherman.

Therefore, when the underwater glider is submerged and the fluid is injected or discharged into the buoyancy tank, the underwater glider is raised and lowered in the water due to the change in the buoyancy generated as the specific gravity of the underwater glider changes. At this time, the underwater glider Goes up and down while advancing at a certain angle.

These underwater gliders are widely used because they move forward while ascending and descending due to changes in buoyancy generated by injecting or discharging fluid into a buoyancy tank using a pump, and thus has an advantage of being able to search for a long time with very high power efficiency and low power.

However, since the underwater glider is usually affected by the surrounding fluid during underwater operation, a technology capable of stabilizing the underwater motion of the underwater glider is required.

Korean Patent Registration No. 10-1658112 Korean Patent Registration No. 10-1175235

An aspect of the present invention is an apparatus and method for predicting flight trajectory of an underwater glider navigation system capable of predicting the position of injury after movement by depth using the marine environment characteristics and the physical characteristics of the underwater glider itself when operating an underwater glider, and the method. It provides a recording medium for performing.

The technical problem of the present invention is not limited to the technical problem mentioned above, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

The method for designing an environmentally adaptive flight model of an underwater glider according to an embodiment of the present invention is to fly by receiving at least one of data measured by an underwater glider, marine environment data required for a flight model, and flight characteristic data of an underwater glider. Setting basic parameters of the model; Calculating a vertical speed of the underwater glider based on the set basic parameters; Setting initial conditions of flight parameters for determining flight characteristics of the underwater glider using the calculated vertical speed; Calculating the entry angle of the underwater glider through numerical computation based on the initial conditions of the flight parameters; Calculating a vertical speed from the flight model based on the calculated entry angle; And calculating a cost function from the calculated vertical speed, and determining a flight parameter when the cost function becomes a minimum value as a final flight parameter of the flight model.

In one embodiment, the determining as the final flight parameter may include calculating a cost function from the calculated vertical speed; Repeatedly calculating the vertical speed of the flight model while changing the numerical value of the flight parameter until the calculated cost function reaches the minimum value; And determining a flight parameter whose cost function is the minimum value as a final flight parameter of the flight model.

In one embodiment, the step of determining the final flight parameter comprises calculating the vertical movement speed (dz/dt) of the underwater glider through the vertical trajectory data of the underwater glider, and then calculating the vertical movement speed of the underwater glider so that the cost function becomes the minimum value. Each flight parameter can be determined as the final flight parameter by calculating the speed.

이하가 될 때까지 계산을 반복 수행할 수 있다.In one embodiment, the step of determining as the final flight parameter, the gradient value of the cost function is

The calculation can be repeated until it becomes the following.

In one embodiment, the step of setting the basic parameters may receive data measured from an internal sensor of the underwater glider through a test flight or data including previously measured data as basic data.

In one embodiment, the calculating of the vertical speed may include interpolating flight characteristic data of the underwater glider; Calculating depth data based on the interpolated flight characteristic data and marine environment data; And calculating the vertical speed of the underwater glider based on the calculated depth data.

In one embodiment, the interpolating the flight characteristic data of the underwater glider may interpolate the flight characteristic data of the underwater glider at 1 second intervals.

In an embodiment, in the calculating of the depth data, depth data may be calculated based on at least one of density data and pressure data.

In an embodiment, the calculating of the vertical speed may further include reducing noise of the calculated vertical speed and performing filtering.

In an embodiment, in the performing of the filtering, noise may be reduced through a centered differential method, and 10s low-pass boxcar filtering may be performed.

In one embodiment, the step of setting the basic parameters includes gravitational acceleration, the volume of the underwater glider, the mass of the underwater glider, the initial temperature, and the area of the underwater glider ( glider area), thermal expansion coefficient, lift coefficient, induced drag coefficient, ocean density, ocean pressure, ocean temperature ), at least one of a volume change of the underwater glider and a pitch of the underwater glider may be set as a basic parameter.

In an embodiment, the flight parameter may be determined as at least one of a parasite drag coefficient, compressibility, and extra buoyancy.

In an embodiment, it may further include updating the flight model with the determined final flight parameters.

In an embodiment, it may further include predicting the flight trajectory of the underwater glider from the flight model based on the determined final flight parameters.

In an embodiment, it may further include the step of visually providing a flight parameter in a graph when the cost function becomes a minimum value.

In one embodiment, it may further include the step of dividing the state of the underwater glider into three types of diving, hovering, and surfacing.

In a computer-readable storage medium according to another embodiment of the present invention, a computer program for performing an environmentally adaptive flight model design method of an underwater glider is recorded.

An apparatus for designing an environmentally adaptive flight model of an underwater glider according to another embodiment of the present invention receives at least one of data measured by an underwater glider, marine environment data required for a flight model, and flight characteristic data of an underwater glider. A basic parameter setting unit for setting basic parameters of the flight model; A vertical speed calculation unit that calculates a vertical speed of the underwater glider based on the set basic parameters; An initial condition setting unit for setting initial conditions of flight parameters for determining flight characteristics of the underwater glider using the calculated vertical speed; An entry angle calculation unit for calculating an entry angle of the underwater glider through numerical computation based on the initial conditions of the flight parameters; A vertical speed calculator that calculates a vertical speed from the flight model based on the calculated entry angle; And a final flight parameter determination unit that calculates a cost function from the calculated vertical speed and determines a flight parameter when the cost function becomes a minimum value as a final flight parameter of the flight model.

In an embodiment, a monitoring unit may further include a monitoring unit that visually provides a graph of flight parameters when the cost function becomes a minimum value.

In one embodiment, the final flight parameter determining unit, a cost function calculating unit for calculating a cost function from the calculated vertical speed; An iterative calculation unit that repeatedly calculates the vertical speed of the flight model while changing the value of the flight parameter until the calculated cost function reaches a minimum value; And a parameter determination unit that determines a flight parameter whose cost function is the minimum value as a final flight parameter of the flight model.

According to one aspect of the present invention described above, it can be applied even if the seawater density structure of the target sea area changes during operation, and it can also be applied to the change in flight characteristics due to attachment of organisms that occur during long-term operation.

According to another aspect of the present invention described above, it can be applied to the weight fluctuation of the underwater glider due to the attachment of additional sensors or equipment, and it is possible to predict the flight trajectory with higher accuracy if the underwater glider has passed the test flight once.

1 is a diagram illustrating a balance of forces acting on an underwater glider.
2 is a view illustrating the direction of force for each component during cruising flight of an underwater glider.
3 is a diagram illustrating an apparatus for designing an environmentally adaptive flight model of an underwater glider according to an embodiment of the present invention.
4 is a flowchart illustrating a method of designing an environmentally adaptive flight model of an underwater glider according to an embodiment of the present invention.
5 is a flowchart illustrating a step of determining the final flight parameter in FIG. 4.
6 is a flow chart illustrating the steps of calculating the vertical speed in FIG. 4.
7 to 10 are graphs showing the cost function change according to each parameter.
11 to 14 are graphs of comparison between results obtained by the present invention and actual data.
15 to 17 are graphs showing the estimated entry angle calculated through the optimization process according to the present invention in time series.
18 and 19 are graphs evaluating the performance of the vertical flight trajectory of the underwater glider predicted by the present invention.

DETAILED DESCRIPTION OF THE INVENTION The detailed description of the present invention to be described later refers to the accompanying drawings, which illustrate specific embodiments in which the present invention may be practiced. These embodiments are described in detail sufficient to enable a person skilled in the art to practice the present invention. It is to be understood that the various embodiments of the present invention are different from each other, but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention in relation to one embodiment. In addition, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description to be described below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scopes equivalent to those claimed by the claims. Like reference numerals in the drawings refer to the same or similar functions over several aspects.

The underwater glider moves by flying underwater according to the mission set by the buoyancy engine, and the change of posture is controlled by changing the internal center of gravity.

It is possible to set a flight model based on static parameters based on the physical shape of the underwater glider and dynamic parameters for movement in the water, and can be used to estimate the position of the flight after movement through the simulation of the flight model.

Based on the theoretical flight model, the difference between the result of the simulation for the designated depth and the flight data in the actual sea area is the effect of the sea current, and the sea current is estimated by calculating this vector difference, and the underwater glider flight trajectory using the estimated sea current. Can be adjusted.

In addition, in order to stably operate the underwater glider, it is essential to verify the operational stability using a simulator that can predict track stability through path maintenance accuracy analysis after confirming in advance how the underwater glider will move horizontally. A flight model that predicts the maneuvering trajectory of an underwater glider more realistically is very important.

Furthermore, by analyzing the test flight results in the actual sea area, an accurate flight model is also essential in optimizing the buoyancy parameters so that the flight model can be improved and the underwater glider can exhibit maximum performance in the sea area. Based on this, since it is also necessary to develop a system that enables the most efficient flight, an environmentally adaptive hydrodynamic underwater glider flight model (Adaptive Glider Flight Model, AGFM) must be developed first.

Specifications and parameters of a general underwater glider are as follows.

It is possible to design a flight model calculated from the dynamic model of the motion in the water and static parameters according to the physical shape and specifications of the underwater glider.

The SLOCUM underwater glider capable of submerging 1000 meters is equipped with a buoyancy engine capable of changing the volume of up to ±270cm3, and the result of the volume change control is recorded as an internal data parameter, ‘m_de_oil_vol’.

The weight of the underwater glider is basically 56Kg, the HullDiameter is 22cm and the length is 1.5m. The average moving speed in the vertical direction is 0.2m/s, and the average moving speed in the horizontal direction is 0.4m/s, which may vary depending on the depth of the submarine and the marine environment.

The CTD (Conductivity, Depth, Temperature) sensor is equipped with the Seabird SBE41 CTD model, and the Micron MP50-2000 model is used as a sensor for underwater pressure (depth) measurement.

During underwater flight, the depth measurement sensor data is recorded as an internal data parameter of ‘m_depth’, and information on whether the depth state is currently descending, rising, or on the surface is recorded as ‘m_depth_state’.

The underwater glider's attitude measurement sensor is equipped with a PNI TCM3 sensor, and information about the underwater attitude such as the roll, pitch, and yaw of the underwater glider is recorded as internal data parameters'm_roll','m_pitch', and'm_heading'. do.

After completing the underwater flight, when you come to the surface, the current position is measured by the GPS sensor, and these are recorded as internal parameters ‘m_gps_lat’ and ‘m_gps_long’.

Referring to Figure 1, it is possible to check the balance of the force acting on the underwater glider.

Other parameters related to the shape of the underwater glider are shown in Table 1.

The parameter-based flight model of the existing underwater glider is as follows.

Assuming that the underwater glider is in a cruising state when flying underwater, a simplified equation of motion can be set as shown in Equation 1.

는 항력(drag force),

는 양력(lift force),

는 부력(buoyancy force),

는 중력(gravity force)이고,

는 글라이드 각(glide angle)이다.From here,

Is the drag force,

Is the lift force,

Is the buoyancy force,

Is the gravity force,

Is the glide angle.

Referring to FIG. 2, it is possible to check the direction of force for each component during cruising flight of the underwater glider.

)과 양력(

)은, 유체의 밀도(

) 와 사영 면적(

), 상대 속도(

), 항력 계수(

, drag coefficient), 양력 계수(

, lift coefficient)에 대해 아래의 수학식 2로 정의될 수 있다.Of these, drag (

) And lift (

) Is the density of the fluid (

) And projected area (

), relative speed (

), drag coefficient (

, drag coefficient), lift coefficient (

, lift coefficient) can be defined by Equation 2 below.

, Lift coefficient)는 수중글라이더의 선체(hull)와 날개(wing)에서의 양력-슬로프 계수(lift-slope coefficient)인

와

를 사용하여 아래의 수학식 3과 같이 표현될 수 있다.Lift coefficient (

, Lift coefficient) is the lift-slope coefficient of the underwater glider's hull and wing.

Wow

It can be expressed as Equation 3 below by using.

, Drag coefficient)는 기생 항력 계수(parasite drag coefficient)인

와 유도 항력 계수(induced drag coefficient)인

을 사용하여 아래의 수학식 4와 같이 표현될 수 있다.Drag coefficient (

, Drag coefficient) is the parasite drag coefficient

And the induced drag coefficient

It can be expressed as Equation 4 below by using.

, Angle of Attack)은 항력과 양력에 대한 방정식을 통해 아래의 수학식 5와 같이 구할 수 있다.Entry angle(

, Angle of Attack) can be obtained as in Equation 5 below through equations for drag and lift.

, pitch angle)과 수중글라이더 속도(U)를 알면 진입각(

)을 계산할 수 있으며, 피치각(pitch angle)과 심도율(depth rate)에 의한 수직방향 이동 속도를 사용하여 진입각 계산을 위해 아래의 수학식 6의 근사식을 사용할 수 있다.Given pitch angle(

, pitch angle) and underwater glider speed (U), the entry angle (

) Can be calculated, and the approximation of Equation 6 below can be used to calculate the entry angle by using the vertical movement speed based on the pitch angle and the depth rate.

However, there is a problem that the approximation formula such as Equation 6 cannot be utilized if the buoyancy condition of the underwater glider or the environmental conditions of the ocean is different, and the accuracy of the approximation itself is low, and thus it is difficult to practically use it.

[m/s])와 예측된 수평 속도(

), 진입각(

[rad], Angle of Attack)은 다음의 수학식 7과 같은 관계를 가지며, 이러한 모델을 바탕으로 시간 변화에 따른 수직 방향의 이동 속도를 계산하고, 제어 입력으로 설정된 피치(pitch) 각도와 계산된 진입 각도를 이용하여 수평 방향의 이동 속도 및 이동량을 계산할 수 있다.The vertical velocity expressed as a function of the measured pressure sensor output relationship over the time axis (

[m/s]) and predicted horizontal velocity (

), entry angle (

[rad], Angle of Attack) has the relationship as shown in Equation 7 below, based on this model, calculates the moving speed in the vertical direction according to time, and calculates the calculated pitch angle and the calculated The moving speed and amount of movement in the horizontal direction can be calculated using the entry angle.

The existing parameter-based flight model is a method of calculating the horizontal speed based on the vertical speed by approximating the entry angle or setting it to zero, and is currently being used as the basic flight model of the SLOCUM underwater glider.

Such a parameter-based flight model is highly efficient due to its fast calculation time based on simplicity, but the problem that accuracy is significantly lowered when the buoyancy conditions of the underwater glider and the density structure of the ocean are changed. It has a problem that it is highly likely to distort the glider trajectory.

Therefore, by directly calculating the various parameters of the above-described flight model through an optimization algorithm to best explain the measured trajectory data, the accuracy of the flight trajectory prediction is greatly improved, and the buoyancy parameter changes or the ocean density situation is changed. There has been a need to develop an environmentally adaptive flight model that can be flexibly applied even if it changes.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

3 is a diagram illustrating an apparatus for designing an environmentally adaptive flight model of an underwater glider according to an embodiment of the present invention.

3, an apparatus for designing an environmentally adaptive flight model of an underwater glider includes a basic parameter setting unit 100, a vertical speed calculation unit 200, an initial condition setting unit 300, an entry angle calculation unit 400, It includes a vertical speed calculation unit 500 and a final flight parameter determination unit 600.

The basic parameter setting unit 100 receives at least one of data measured by the underwater glider, marine environment data required for the flight model, and flight characteristic data of the underwater glider and sets basic parameters of the flight model.

The vertical speed calculation unit 200 calculates the vertical speed of the underwater glider based on the basic parameters set by the basic parameter setting unit 100.

The initial condition setting unit 300 sets initial conditions of flight parameters that determine flight characteristics of the underwater glider using the vertical speed calculated by the vertical speed calculation unit 200.

The entry angle calculation unit 400 calculates the entry angle of the underwater glider through numerical computation based on the initial conditions of the flight parameters set in the initial condition setting unit 300.

The vertical speed calculation unit 500 calculates a vertical speed from the flight model based on the entry angle calculated by the entry angle calculation unit 400.

The final flight parameter determination unit 600 calculates a cost function from the vertical speed calculated by the vertical speed calculation unit 500, and calculates a flight parameter when the cost function becomes a minimum value as the final flight parameter of the flight model. To decide.

In one embodiment, the final flight parameter determination unit includes a cost function calculation unit that calculates a cost function from the calculated vertical speed, and iteratively changes the vertical speed of the flight model while changing the value of the flight parameter until the calculated cost function reaches a minimum value. It may include an iterative calculation unit calculated as and a parameter determining unit determining a flight parameter having a minimum cost function as a final flight parameter of the flight model.

An environmentally adaptive flight model design apparatus for an underwater glider having the configuration as described above is a monitoring unit that visually provides a graph by showing a flight parameter when the cost function becomes a minimum value (not shown in the drawing for convenience of explanation) It may further include.

4 is a flowchart illustrating a method of designing an environmentally adaptive flight model of an underwater glider according to an embodiment of the present invention.

Referring to FIG. 4, the method of designing an environmentally adaptive flight model of an underwater glider receives at least one of data measured by an underwater glider, marine environment data required for a flight model, and flight characteristic data of an underwater glider, and Basic parameters are set (S410).

In one embodiment, the step of setting the basic parameters (S410) includes gravitational acceleration, a glider volume, an underwater glider mass, an initial temperature, and an underwater glider. Area (glider area), thermal expansion coefficient, lift coefficient, induced drag coefficient, ocean density, ocean pressure, ocean temperature ( water temperature), a volume change of the underwater glider, and a pitch of the underwater glider may be set as a basic parameter.

In an embodiment, in the step of setting the basic parameters (S410), data measured from an internal sensor of the underwater glider through a test flight or data including previously measured data may be input as basic data.

The vertical speed of the underwater glider is calculated based on the basic parameters set in step S410 (S420).

The initial conditions of the flight parameters for determining the flight characteristics of the underwater glider are set for numerical optimization using the vertical speed calculated in step S420 described above (S430).

In an embodiment, the flight parameter may be determined as at least one of a parasite drag coefficient, a compressibility, and an extra buoyancy.

The angle of attack of the underwater glider is calculated through numerical computation based on the initial conditions of the flight parameters set in the above-described step S430 (S440).

The vertical speed is calculated from the flight model based on the entry angle calculated in step S440 (S450).

The method of calculating the entry angle and the vertical speed according to steps S440 and S450 as described above is as follows.

The present invention can calculate a flight parameter that determines the flight characteristics of the underwater glider based on an equation of motion established by assuming a situation in which a mechanical balance is achieved in the cruising state of the underwater glider.

This type of adaptive glider flight model (AGFM) is a flight model developed and utilized by a team with the most advanced operating technology in developed countries, and is the most efficient and accurate flight model.

In the case of underwater gliders, most of the flight path can be viewed as such a cruising state, so the equation of motion based on the mechanical balance can explain the flight trajectory of more than 90% (when flying over 200m, the percentage increases as the depth increases). In addition, the remaining 10% or less is a section in which acceleration occurs, so it can be predicted through empirical interpolation.

Assuming vertical mechanical balance, the equation of motion can be simplified as shown in Equation 8 below.

는 부력(buoyancy force),

는 중력(gravity force),

는 수중글라이더의 피치,

는 항력(drag force),

는 양력(lift force)이고,

는 진입각이다.From here,

Is the buoyancy force,

Is the gravity force,

Is the pitch of the underwater glider,

Is the drag force,

Is the lift force,

Is the angle of entry.

The difference between buoyancy and gravity may be calculated as the difference between the volume change and weight of the underwater glider as shown in Equation 9 below.

는 해양의 밀도,

는 여분의 부피, T는 온도, S는 수중글라이더의 면적,

은 압축성, P는 해양의 압력,

는 열팽창 계수,

는 오일 펌프에 있는 오일의 부피이고,

는 수중글라이더의 질량이다.From here,

Is the density of the ocean,

Is the extra volume, T is the temperature, S is the area of the underwater glider,

Is compressibility, P is ocean pressure,

Is the coefficient of thermal expansion,

Is the volume of oil in the oil pump,

Is the mass of the underwater glider.

In horizontal mechanical balance, a relational expression such as Equation 10 below can be obtained.

은 기생 항력 계수이이고,

는 유도 항력 계수이고, U는 수중글라이더의 속력이고,

은 양력 계수이고,

는 비행 시 저항을 받는 수중글라이더의 면적이다.From here,

Is the parasitic drag coefficient is,

Is the induced drag coefficient, U is the speed of the underwater glider,

Is the lift coefficient,

Is the area of the underwater glider that is resisted during flight.

If Equation 8 to Equation 10 are summarized, it can be simplified into one equation such as Equation 11 below.

Where g is the acceleration due to gravity.

Accordingly, the vertical speed (w) of the underwater glider can be summarized by Equation 12 below.

)은 비행 파라미터가 결정되면 다음의 수학식 13과 같은 방정식으로 계산 가능하다.As described above, the angle of entry (

) Can be calculated by the following equation (13) when the flight parameters are determined.

A cost function is calculated from the vertical speed calculated in step S450 described above, and a flight parameter when the cost function becomes the minimum value (in the case of Yes in S470 in FIG. 4) is determined as the final flight parameter of the flight model. (S460).

), 수중글라이더 질량 (

) 및 초기 온도 (

) 등은 측정 가능한 값이며, 항력(drag)에 영향을 주는 수중글라이더 면적인 S는 항력(drag)과 양력 계수(lift coefficient)를 통해 산출할 수 있다.Among the parameters of underwater glider, gravity acceleration (g), underwater glider volume (

), underwater glider mass (

) And initial temperature (

) Is a measurable value, and the underwater glider area S that affects drag can be calculated through drag and lift coefficient.

), 압력(P) 및 수온(T) 등은 수중글라이더에 측정되거나 기존의 측정된 자료를 활용할 수 있으며, 수중글라이더 부피 변화(

)와 피치(

)는 수중글라이더 내부 센서에서 측정되는 값이기 때문에 측정치를 활용할 수 있다.Also, seawater density (

), pressure (P), and water temperature (T) can be measured on an underwater glider or use existing measured data, and the volume change of the underwater glider (

) And pitch(

) Is the value measured by the sensor inside the underwater glider, so the measured value can be used.

, lift coefficient), 항력 계수(drag coefficents), 압축성(

, compressibility), 팽창 계수(

, expansion coefficient) 및 여분의 부력(

, extra buoyancy)이다.However, it is difficult to know the exact value among the parameters of the underwater glider, and the parameter that may vary depending on the state of the underwater glider is the lift coefficient (

, lift coefficient), drag coefficents, compressibility (

, compressibility), expansion coefficient (

, expansion coefficient) and extra buoyancy (

, extra buoyancy).

This parameter is different for each underwater glider, but it is a parameter that can be considered to be almost the same within a specific mission.It is important to consider this because the volume of an underwater glider changes according to the change of pressure and water temperature according to the depth of the water. Since extra buoyancy may occur depending on the unique characteristics, a parameter to consider this should be added.

The flight model according to the present invention can optimize and calculate each flight parameter using the least squares method by utilizing flight trajectory data obtained through one or two test flights. Equation 14 below is a cost function (J) for optimization according to the present invention.

Each flight parameter can be calculated by calculating the vertical movement speed (dz/dt) of the underwater glider using the vertical trajectory data of the underwater glider and calculating w, which best describes the vertical movement speed.

The method for designing an environmentally adaptive flight model of an underwater glider having the steps as described above includes updating the flight model with the determined final flight parameters, and predicting the flight trajectory of the underwater glider from the flight model based on the determined final flight parameters. It may further include a step of visually providing a flight parameter by graphing the flight parameters when the steps and cost functions become the minimum values.

In the method of designing an environmentally adaptive flight model of an underwater glider having the above-described steps, the state of the underwater glider can be classified into three types: diving, hovering, and surfacing.

5 is a flowchart illustrating a step of determining the final flight parameter in FIG. 4.

Referring to FIG. 5, in the step of determining the final flight parameter (S460), a cost function is calculated from the vertical speed calculated in step S450 (S461).

The vertical speed of the flight model is repeatedly calculated while changing the value of the flight parameter until the cost function calculated in the above-described step S461 becomes the minimum value (S462).

During the iterative calculation of the vertical speed of the flight model in step S462, a flight parameter whose cost function becomes the minimum value is determined as the final flight parameter of the flight model (S463).

In the step of determining the final flight parameter having the above-described steps (S460), after calculating the vertical moving speed (dz/dt) of the underwater glider through the vertical trajectory data of the underwater glider, the cost function is made to be the minimum value. By calculating the vertical speed of the underwater glider, each flight parameter can be determined as the final flight parameter.

이하가 될 때까지 계산을 반복 수행할 수 있다.In the step of determining the final flight parameter having the steps described above, the gradient value of the cost function is

The calculation can be repeated until it becomes the following.

6 is a flow chart illustrating the steps of calculating the vertical speed in FIG. 4.

Referring to FIG. 6, in the step of calculating the vertical speed (S420), flight characteristic data of the underwater glider is interpolated (S421).

In one embodiment, the interpolation of flight characteristic data of the underwater glider among the basic parameters set in step S410 described above (S421) may interpolate the flight characteristic data of the underwater glider at 1 second intervals.

Depth data is calculated based on marine environment data among the flight characteristic data interpolated in step S421 and the basic parameters set in step S410 described above (S422).

In an embodiment, in the calculating of depth data (S422), depth data may be calculated based on at least one of density data and pressure data.

The vertical speed of the underwater glider is calculated based on the depth data calculated in step S422 (S423).

The step of calculating the vertical speed having the above-described steps (S420) may further include reducing noise of the calculated vertical speed and performing filtering.

In an embodiment, performing filtering may reduce noise through a centered differential method and perform 10s low-pass boxcar filtering.

Since the flight model according to the present invention is a nonlinear equation, each flight parameter can be determined through a nonlinear optimization algorithm.

In order to evaluate the effect of each flight parameter on the cost function, a sensitivity analysis is conducted to review the parameter setting work to increase the efficiency of the flight model optimization algorithm.

7 to 10 are graphs showing the cost function change according to each parameter.

, parasite drag coefficient)에 따라 기본적으로 크게 좌우되는 것을 알 수 있어, 비행 모델을 최적화하는데 있어서 매우 중요한 파라미터인 것을 알 수 있다.7 to 10, looking at the cost function change according to each flight parameter, the parasitic drag coefficient (

, parasite drag coefficient), it can be seen that it is a very important parameter in optimizing the flight model.

, compressibility) 및 여분의 부력(

, extra buoyancy)파라미터 역시 비용함수가 최소가 되는 지점이 뚜렷하게 나타나므로 비행 모델 최적화에 있어 중요한 파라미터임을 알 수 있다.In addition, compressibility (

, compressibility) and extra buoyancy (

, extra buoyancy) parameter is also an important parameter in flight model optimization because the point where the cost function is minimized is clearly indicated.

, thermal expansion coefficient)와 양력 계수(

, lift coefficient)는 파라미터 변화에 따라 비용함수 변화가 크게 영향을 받지 않는 것을 볼 수 있으며, 이것은 비용함수 자체가 해당 파라미터에 크게 민감하지 않음을 나타내는 것이다.However, the coefficient of thermal expansion (

, thermal expansion coefficient) and lift coefficient (

, lift coefficient) can be seen that the cost function change is not significantly affected by the parameter change, indicating that the cost function itself is not very sensitive to the parameter.

, thermal expansion coefficient)와 양력 계수(

, lift coefficient)의 경우 기존에 측정된 측정값을 활용하고, 나머지 세 가지 파라미터인 기생 항력 계수(

, parasite drag coefficient), 압축성(

, compressibility) 및 여분의 부력(

, extra buoyancy)을 최적화하는 비행 파마미터로 결정하였다.Accordingly, in the present invention, the coefficient of thermal expansion (

, thermal expansion coefficient) and lift coefficient (

In the case of, lift coefficient), the previously measured value is used, and the remaining three parameters, the parasitic drag coefficient (

, parasite drag coefficient), compressibility (

, compressibility) and extra buoyancy (

, extra buoyancy) to optimize flight parameters.

Since the flight parameters to be optimized were determined based on the analysis result, an environmentally adaptive underwater glider flight model algorithm according to the present invention was established based on this.

Next, the comparison between the predicted result and the actual data is reviewed.

11 to 14 are graphs comparing results predicted by the present invention and actual data.

11 to 14, the flight trajectory results obtained in the Ulleungdo-Dokdo round-trip flight test performed in June 2016 were compared with the results of the present invention.

The actual flight parameters were calculated using the vertical speed of the underwater glider, and the flight trajectory was predicted from the flight parameters, the marine buoyancy environment data measured by the sensor, and the underwater glider attitude data.

The accuracy was evaluated by comparing the flight trajectory predicted by the present invention with the actual flight trajectory.

It can be seen that despite the results from different real sea tests having different flight trajectories, the trajectories actually obtained with only parameters by the present invention are predicted very similarly.

Since the flight parameters can be calculated through the optimization process according to the present invention, the angle of attack can be estimated using this, and the estimated angle of ingress is very important in accurately calculating the horizontal moving speed of the underwater glider. It can be confirmed that it is a parameter.

15 to 17 are graphs showing the estimated entry angle calculated through the optimization process according to the present invention in time series.

Referring to Fig. 15, it is possible to confirm the change in the angle of entry when the underwater glider ascends and descends obtained from the Ulleungdo long-distance flight test (July 2016). Referring to Fig. 16, the Jumunjin long-distance flight test (2017, 8 When ascending and descending of the underwater glider obtained from Mon), the change in the angle of entry can be confirmed, and referring to FIG. 17, when the underwater glider obtained from the flight test (June 2017) near Mukho Port in the East Sea And it is possible to check the change of the entry angle when descending.

Referring to FIGS. 15 to 17, it can be seen that the entry angle is stably obtained between 2.5° and 3.5° despite the different buoyancy conditions and ocean density conditions. Previously, it was not possible to accurately determine the entry angle of the underwater glider, but this is a result showing that relatively accurate entry angle information can be found through the present invention.

In addition, as the entry angle is obtained almost stably, the accuracy of predicting the horizontal movement distance can be increased, and based on this, the navigation accuracy of the underwater glider can be improved.

It is judged that a slight variation in the angle of entry appears depending on the state of the ocean and the state of the underwater glider.This can be caused by the fact that it is difficult to specify the cause due to the nonlinear characteristics of the underwater glider, but the variation RMS of the entry angle is only about 0.5 degrees. The horizontal distance error is about 30m for 400m submerged, about 8% of the depth of the submerged sea, and when converted to a horizontal speed error, it is a negligible value of 0.008m/s.

18 and 19 are a predicted trajectory to evaluate the performance of the vertical flight trajectory of an underwater glider predicted by the present invention, a position maintenance test performed in June 2017, and the longest distance performed in August 2017. RMS error is calculated by comparing the test results, and calculated as% by comparing with the depth of the submerged port.

By using the flight parameters obtained by the optimization algorithm previously and applying them to the ocean density environment information and the underwater glider attitude information in the next performance evaluation, the flight trajectory is predicted and the predicted results are compared with the actual observation results. The trajectory error was calculated.

It can be seen that the RMS error ratio is generally within about 2%, and the vertical flight trajectory according to the present invention is very accurately predicted. On the other hand, it can be seen that the existing flight model has a much higher error (about 3 to 10 times or more) than the present invention, although it does not take into account the marine environment conditions and the buoyancy characteristics of the underwater glider.

It can be seen that the vertical flight trajectory of the present invention is relatively accurate, and as the calculated entry angle is stably obtained over time, the accuracy of the horizontal movement speed is also higher than that of the existing flight model.

The method for designing an environmentally adaptive flight model of an underwater glider as described above may be implemented as an application or implemented in the form of program instructions that can be executed through various computer components and recorded in a computer-readable recording medium. The computer-readable recording medium may include program instructions, data files, data structures, etc. alone or in combination.

The program instructions recorded in the computer-readable recording medium may be specially designed and constructed for the present invention, and may be known and usable to those skilled in the computer software field.

Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical recording media such as CDROMs and DVDs, magnetic-optical media such as floptical disks. , And a hardware device specially configured to store and execute program instructions such as ROM, RAM, flash memory, and the like.

Examples of the program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform processing according to the present invention, and vice versa.

Although the above has been described with reference to embodiments, it is understood that those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention described in the following claims. You can understand.

According to the present invention, an environmentally adaptive flight model determined by optimizing marine environment characteristics and a corresponding underwater glider based on a static hydrodynamic equation can be applied even if the seawater density structure of the target sea area changes during operation. In addition, it can be applied to fluctuations in flight characteristics due to attachment of organisms that occur during long-term operation.

In addition, since it is a method that calculates the characteristic values by optimizing for the underwater glider, it can be applied to changes in the weight of the underwater glider due to the attachment of additional sensors or equipment. For this reason, it can be used importantly in establishing an operation mission plan or operation strategy of an underwater glider.

100: basic parameter setting unit
200: vertical speed calculation unit
300: initial condition setting unit
400: entry angle calculation unit
500: vertical speed calculation unit
600: final flight parameter determination unit

Claims (20)

Receiving at least one of data measured by the underwater glider, marine environment data required for the flight model, and flight characteristic data of the underwater glider and setting basic parameters of the flight model;
Calculating a vertical speed of the underwater glider based on the set basic parameters;
Setting initial conditions of flight parameters for determining flight characteristics of the underwater glider using the calculated vertical speed;
Calculating the entry angle of the underwater glider through numerical computation based on the initial conditions of the flight parameters;
Calculating a vertical speed from the flight model based on the calculated entry angle; And
Computing a cost function from the calculated vertical speed, and determining a flight parameter when the cost function becomes a minimum value as a final flight parameter of the flight model,
Calculating the vertical speed from the flight model based on the calculated entry angle,
The vertical speed is calculated from the flight model based on the calculated entry angle, parasite drag coefficient, compressibility, extra buoyancy, and the volume of oil in the oil pump,
The step of determining as the final flight parameter,
Calculating a vertical moving speed (dz/dt) of the underwater glider through vertical trajectory data of the underwater glider, calculating a cost function from the calculated vertical moving speed (dz/dt) and the calculated vertical speed;
Repeatedly calculating the vertical speed of the flight model while changing the numerical value of the flight parameter until the calculated cost function reaches the minimum value; And
A method for designing an environmentally adaptive flight model of an underwater glider comprising the step of determining a flight parameter whose cost function is a minimum value as a final flight parameter of the flight model.
delete delete The method of claim 1, wherein the determining as the final flight parameter,
The gradient value of the cost function is

An environmentally adaptive flight model design method of an underwater glider, characterized in that the calculation is repeatedly performed until the following.
The method of claim 1, wherein the setting of the basic parameter comprises:
A method for designing an environmentally adaptive flight model of an underwater glider, characterized in that data measured from an internal sensor of an underwater glider through a test flight or data including previously measured data are input as basic data.
The method of claim 1, wherein calculating the vertical velocity comprises:
Interpolating flight characteristic data of the underwater glider;
Calculating depth data based on the interpolated flight characteristic data and marine environment data; And
An environmentally adaptive flight model design method of an underwater glider comprising the step of calculating the vertical speed of the underwater glider based on the calculated depth data.
The method of claim 6, wherein interpolating flight characteristic data of the underwater glider,
An environmentally adaptive flight model design method of an underwater glider, characterized in that interpolation of the flight characteristic data of the underwater glider at 1-second intervals.
The method of claim 6, wherein calculating the depth data comprises:
An environmentally adaptive flight model design method of an underwater glider, characterized in that the depth data is calculated based on at least one of density data and pressure data.
The method of claim 6, wherein calculating the vertical speed,
The method of designing an environmentally adaptive flight model of an underwater glider, further comprising the step of reducing the calculated vertical speed noise and performing filtering.
The method of claim 9, wherein performing the filtering comprises:
A method of designing an environmentally adaptive flight model of an underwater glider, characterized in that noise is reduced and filtering is performed through a centered differential method.
The method of claim 1, wherein the setting of the basic parameter comprises:
Gravitational acceleration, underwater glider volume, underwater glider mass, initial temperature, underwater glider area, thermal expansion coefficient, lift coefficient (lift coefficient), induced drag coefficient, ocean density, ocean pressure, ocean temperature, underwater glider volume change and underwater glider An environmentally adaptive flight model design method of an underwater glider, characterized in that at least one parameter among the pitches of is set as a basic parameter.
delete The method of claim 1,
An environmentally adaptive flight model design method of an underwater glider, further comprising the step of updating the flight model with the determined final flight parameters.
The method of claim 1,
Predicting the flight trajectory of the underwater glider from the flight model based on the determined final flight parameters. The method of designing an environmentally adaptive flight model of an underwater glider, characterized in that it further comprises.
The method of claim 1,
A method for designing an environmentally adaptive flight model of an underwater glider, further comprising the step of visually providing a flight parameter when the cost function becomes a minimum value in a graph.
The method of claim 1,
The method of designing an environmentally adaptive flight model of an underwater glider, further comprising the step of dividing the state of the underwater glider into three categories: diving, hovering, and surfacing.
In order to perform the method for designing an environmentally adaptive flight model of an underwater glider according to any one of claims 1, 4 to 11, and 13 to 16, a computer program is recorded and readable by a computer. Recording medium.
A basic parameter setting unit configured to receive at least one of data measured by the underwater glider, marine environment data necessary for the flight model, and flight characteristic data of the underwater glider and set basic parameters of the flight model;
A vertical speed calculation unit that calculates a vertical speed of the underwater glider based on the set basic parameters;
An initial condition setting unit for setting initial conditions of flight parameters for determining flight characteristics of the underwater glider using the calculated vertical speed;
Entry angle calculation unit for calculating the entry angle of the underwater glider through numerical calculation (num erical computation) based on the initial conditions of the flight parameters;
A vertical speed calculator that calculates a vertical speed from the flight model based on the calculated entry angle; And
Comprising a final flight parameter determination unit that calculates a cost function from the calculated vertical speed, and determines a flight parameter when the cost function becomes a minimum value as a final flight parameter of the flight model,
The vertical speed calculation unit,
The vertical speed is calculated from the flight model based on the calculated entry angle, parasite drag coefficient, compressibility, extra buoyancy, and the volume of oil in the oil pump,
The final flight parameter determination unit,
A cost function calculation unit that calculates the vertical movement speed (dz/dt) of the underwater glider through vertical trajectory data of the underwater glider, and calculates a cost function from the calculated vertical movement speed (dz/dt) and the calculated vertical speed;
An iterative calculation unit that repeatedly calculates the vertical speed of the flight model while changing the value of the flight parameter until the calculated cost function reaches a minimum value; And
An apparatus for designing an environmentally adaptive flight model of an underwater glider, comprising a parameter determination unit that determines a flight parameter whose cost function is the minimum value as a final flight parameter of the flight model.
The method of claim 18,
An apparatus for designing an environmentally adaptive flight model of an underwater glider, further comprising a monitoring unit that visually provides a graph of flight parameters when the cost function becomes a minimum value.
delete

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