CN108253934B - Underwater terrain survey simulation method and its simulator - Google Patents

Abstract

The invention relates to the technical field of marine surveying and mapping, in particular to an underwater terrain surveying simulation method and a simulator thereof. The user changes the speed and rudder angle of the simulated measurement ship through the measurement ship simulation controller, calculates the position of the simulated measurement ship through the position simulation algorithm; sends the GPS positioning signal to the host computer through the positioning signal simulation algorithm; generates the measurement ship through the attitude simulation algorithm The sounder's sound wave emission direction of the ship's attitude; the instantaneous tidal water level is calculated by the tide prediction algorithm, according to the user-defined period; the measurement result of the instantaneous water depth is calculated by the water depth simulation algorithm, and sent to the upper computer installed with the underwater topographic measurement, navigation and acquisition software . Provides hydrographic navigation acquisition software with measurements similar to real bathymetry without wading measurements. The purpose of the present invention is to provide users with a realistic water depth measurement environment through the simulated underwater terrain measurement signal generated by the simulation system.

Description

Underwater terrain survey simulation method and its simulator

technical field

The invention relates to the technical field of marine surveying and mapping, in particular to an underwater terrain surveying simulation method and a simulator thereof.

Background technique

At present, with the full development of marine and inland water resources development, the demand for underwater topographic survey has increased sharply, and a large number of experienced underwater topographic surveyors are needed. Underwater topographic surveying has high requirements on the work experience of the surveyor. The experienced surveyor can carry out the correct measurement of various underwater targets according to the hydrographic standard, and can also correctly deal with the changes in the sea conditions and hydrological parameters during the surveying process. impact of measurement results. However, because the underwater topographic survey needs to be carried out by a surveying vessel in the ocean or inland rivers, the cost is relatively high. When training surveyors in general colleges and surveying and mapping training institutions, they can only demonstrate the measurement process to the trainees by playing back the measurement results indoors. Although some units with better conditions can use surveying boats for teaching on the water, it is difficult to find various typical underwater targets in the training waters at the same time. These conditions greatly limit the effectiveness and efficiency of bathymetric training. It is an effective way to improve the efficiency and effect of training in indoor simulation training through simulator or simulation trainer. At present, the closest implementation scheme to the present invention is the sounding demonstration function of the sounding instrument. For example, the HD8000X single-beam echo sounder produced by my country Haida Satellite Navigation Technology Co., Ltd. allows users to manipulate the simulated surveying ship to move in the demo interface through the keyboard under the demo interface, and generate fixed simulated water depth data. The disadvantage of the existing technology is that it cannot simulate the real underwater environment. In the demonstration function of the echo sounder, only fixed simulated water depth data can be generated. Changes in sea state and hydrological parameters. Through this demonstration function, the user can only master the most basic bathymetric system operation method, and cannot learn the underwater terrain simulation method in the real underwater environment.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, the technical problem to be solved by the present invention is how to provide measurement results similar to real bathymetry for the hydrographic survey navigation acquisition software without wading measurement. The purpose of the present invention is to provide users with a realistic water depth measurement environment through the simulated underwater terrain measurement signal generated by the simulation system.

In order to achieve the above object, the technical solution of the present invention is to provide a kind of underwater terrain measurement simulation method on the one hand, and its concrete steps include:

Step 1: The user changes the ship speed and rudder angle of the simulated measurement ship through the measurement ship simulation controller. The underwater terrain measurement simulator is controlled by the internal clock of the system according to the ship speed and rudder angle input from the measurement ship simulation controller. Calculate and simulate the position of the survey ship through the position simulation algorithm at a user-defined period;

Step 2: The underwater terrain survey simulator generates a GPS positioning signal with a delay effect according to the position of the simulated survey ship through the positioning signal simulation algorithm, and sends the GPS positioning signal in the required format through the serial port to the user-defined positioning period. host computer;

Step 3: The underwater terrain measurement simulator generates a sounder sound wave emission corresponding to the current moment to measure the attitude of the ship according to the sea state level set by the user and the user-defined period under the control of the internal clock of the system through the simulation algorithm for measuring the ship's attitude. direction;

Step 4: The underwater topographic survey simulator calculates the instantaneous tidal water level according to the tidal harmonic constant stored in the database through the tide forecasting algorithm, and displays it on the screen of the underwater topographic survey simulator according to the user-defined period.

Step 5: The underwater terrain measurement simulator calculates the measurement result of the instantaneous water depth through the water depth simulation algorithm, according to the position of the simulated measurement ship, the sounder sound wave emission direction, and the basic data of the underwater terrain simulation stored in the database, through the serial port. The user-defined format and period send the instantaneous bathymetry results to the upper computer installed with the underwater topographic survey, navigation and acquisition software.

潮流方向变化速度ω，潮流方向随机扰动值Rt，模拟测量船转向灵敏度S，计算出模拟测量船在T1时刻的位置(X1,Y1)，具体算法如下：Further, the position simulation algorithm is to measure the position (X0, Y0) and the heading angle β0 of the ship at time T0, the ship speed V0 and the rudder angle α0 input by the user, the tidal current speed Vr set by the user, and the tidal current direction.

The changing speed of the tidal current direction ω, the random disturbance value Rt of the tidal current direction, the steering sensitivity S of the simulated measuring ship, and the position (X1, Y1) of the simulated measuring ship at the time T1 are calculated. The specific algorithm is as follows:

β1=(β0+V0*△t*α0*S)Mod 360;

Among them: T0 and T1 are two adjacent simulation times, T1=T0+△t, △t is the user-defined clock cycle, the default is 0.1 seconds;

The default value of steering sensitivity S is 0.5, which can be set by the user to any value between {0.1, 0.3, 0.5, 0.7, 0.9, 1.0};

The default value of the flow direction change speed ω is 0.1 degrees/second, which can be set by the user to any value in {0.1, 0.3, 0.5};

The random disturbance value Rt of the power flow direction takes a random number uniformly distributed between -2.0 degrees and +2.0 degrees.

Further, the positioning signal simulation algorithm is to generate a GPS positioning signal with a delay effect according to the delay time set by the user and the current position of the measuring ship. The specific algorithm is as follows:

Step 2.1: Define a one-way linked list to store the position of the surveying ship, each item in the linked list is the position of the surveying ship (X, Y);

Step 2.2: The system calculates the position (X, Y) of the measuring ship according to the position simulation algorithm every time a user-defined clock cycle △t passes, and inserts it into the head of the linked list;

Step 2.3: If the length of the linked list is greater than N=Td/△t, delete the last node of the linked list;

Step 2.4: The system takes out the last node of the linked list according to the positioning signal cycle set by the user, and converts the measurement ship position (X, Y) contained in it into the format required by the host computer and outputs it from serial port 1.

Further, the underwater terrain database includes a water depth data table, a tidal harmonic constant table, and an underwater sound speed profile table; wherein the water depth data table stores the underwater terrain point cloud data of the simulated survey area; the tidal harmonic constant table stores the data. It is the 11 tidal harmonic constants of the simulated survey area; the sound speed profile table stores the sound wave propagation speed at different depths of the simulated survey area. The specific structure of each data table is as follows:

(1) Water depth data sheet

(2) Table of tidal harmonic constants

(3) Underwater sound velocity profile table

Field Name type of data Remark ID Int self-incrementing ID water depth Int water depth speed of sound Decimal underwater sound speed

Further, through the tidal forecast algorithm, according to the tidal harmonic constants stored in the database, the instantaneous tidal water level is calculated and displayed on the screen of the underwater topography simulator according to a user-defined period.

Further, the measurement ship attitude simulation algorithm is to calculate the plane coordinates of the center of the seabed irradiation range of the sound wave emitted by the simulated echo sounder according to the sea state level and the simulated measurement ship position set by the user, and the specific algorithm is as follows:

Step 3.1: Define the position coordinates of the simulated survey ship as (Xc, Yc, 0), query a water depth point P with the smallest distance from the (Xc, Yc) plane from the water depth data table in the database, and take out the water depth value Zp of this point;

Step 3.2: Taking the position (Xc, Yc, 0) of the simulated surveying vessel as the origin of the coordinates, calculate the center of the seabed irradiation range of the sound wave emitted by the simulated echo sounder when the surveying vessel rolls and pitches under the influence of the waves according to the following formula position Xr, Yr, Zr;

In the formula, Roll is the roll angle of the measuring ship, and the value is a random number evenly distributed in the interval [-3*G,+3*G]; Pitch is the pitch angle of the measuring ship, and the value is the interval [-2 *G,+2*G] is a random number uniformly distributed in ;

Step 3.3: Calculate the plane position coordinates (Xcent, Ycent) of the sound wave emitted by the echo sounder in the center of the seabed irradiation area according to the following formula

Among them, Th is the tidal height at the current moment, which is calculated by the tidal prediction algorithm according to the harmonic constant in the database.

Further, the water depth simulation method is to calculate the instantaneous water depth measurement result data obtained by calculating the measurement result data of the instantaneous water depth according to the center position of the sound wave emitted by the sounder on the seabed irradiation range, the basic underwater terrain data, and the sound wave beam angle set by the user. The specific algorithm is as follows. :

Step 5.1: According to the beam angle θ set by the user, the water depth Zp at the location of the measuring ship, and the instantaneous tidal height Th, calculate the radius R=(Zp+Th)*tan(θ );

Step 5.2: Take (Xcent, Ycent) as the center to select 4 candidate points P1 (X _P1 , Y _P1 ), P2 (X _P2 , Y _P2 ), P3 (X _P3 , Y _P3 ), P4 (X _P4 , Y _P4 ) ),in:

Step 5.3: In the sounding data table of the database, retrieve all the neighborhood sounding points whose plane distance to each candidate point is less than R/2, and calculate the plane distance between the candidate point and each neighborhood sounding point, and finally pass the distance inversely proportional The weighted interpolation algorithm calculates the water depths Z1, Z2, Z3, Z4 of the four candidate points P1, P2, P3, and P4;

i＝1，2，3，4；并选取最小的一个Di作为当前位置水深值D；Step 5.4: Calculate the distance between the four candidate points and the position (Xc, Yc, 0) of the simulated echo sounder according to the plane coordinates and water depth of the four candidate points.

i=1, 2, 3, 4; and select the smallest Di as the water depth value D at the current position;

其中i对应从海面开始计算的水深层序号，m为水深D所对应的水深层序号；△Hi为第i层到第i+1层之间的距离，通过两层在数据库中对应的深度相减得到；V_i和V_i+1分别为第i层和第i+1层的水下声速；Step 5.5: According to the underwater sound speed data stored in the database, calculate the total propagation time T of the sound wave corresponding to the water depth D from transmission to reception,

Among them, i corresponds to the sequence number of the water depth calculated from the sea surface, m is the sequence number of the water depth corresponding to the water depth D; △Hi is the distance from the i-th layer to the i+1-th layer. can be obtained by subtracting; V _i and V _i+1 are the underwater sound speeds of the i-th layer and the i+1-th layer, respectively;

其中Vs是用户设定的水下平均声速。Step 5.6: Calculate Instantaneous Bathymetry Results

where Vs is the average underwater sound speed set by the user.

On the other hand, the technical solution provided by the present application is an underwater terrain measurement simulator, which includes, in its logical structure, an underwater terrain measurement simulation software, an underwater terrain simulation database, an underwater terrain measurement simulation device, and a survey ship simulation control. device.

The underwater terrain measurement simulation software is installed in the underwater terrain measurement simulation equipment to receive the ship speed and rudder angle data sent by the user through the measurement ship simulation controller, and real-time according to these data and the basic data stored in the underwater terrain simulation database Calculate the instantaneous water depth signal and satellite positioning signal, and send it to the underwater topographic survey, navigation and acquisition system through the serial port on the device;

The underwater terrain simulation database is used to provide various basic data for calculating the simulation data for the underwater terrain measurement simulation software, including the underwater terrain point cloud data of the simulated survey area, the tidal harmonic constant of the simulated survey area, and the underwater sound speed profile data;

The underwater terrain measurement simulation equipment is used to install the underwater terrain measurement simulation software and the underwater terrain simulation database. A main board and a hard disk, the main board integrates CPU, memory and graphics card; the underwater terrain measurement simulation equipment is used to run the underwater terrain measurement simulation software, and provides an interface for sending data to the outside world; the liquid crystal display screen is used to display the ship speed, Heading, rudder angle, beam angle, tidal flow velocity, tidal flow direction, tidal height, simulator working status information;

The survey ship simulation controller is a standard Windows game joystick (steering wheel), which is used to provide users with a platform to manipulate the simulated survey ship, and is connected to the underwater terrain survey simulation device through a USB transmission line; The buttons on the controller can change the speed and rudder angle of the simulated measurement ship, and the parameters of the simulator can also be set through the buttons on the controller.

Explanation of terms in the present invention:

Underwater topographic survey: also known as bathymetry, hydrographic survey. The survey ship sails on the water surface according to the planned route, and measures the water depth and plane position at the current position through the echo sounder and satellite locator installed on the survey ship, and at the same time conducts tide observation in a specific place in the survey area. Finally, input the observed water depth value, plane position and tidal height into the underwater topographic survey data processing software, and then the underwater topography in the measurement area can be obtained.

Drawing board parameters: Before implementing underwater topographic survey, a drawing board corresponding to the measurement area needs to be established in the underwater topographic survey and navigation acquisition software. The drawing board parameters include the coordinates of the outline points on the drawing board, the drawing board scale, Plate projection type.

Planning survey line: Before implementing underwater topographic survey, it is necessary to lay out several auxiliary lines in the drawing board established by the underwater topographic survey, navigation and acquisition software to represent the route. When conducting underwater topographic survey, the surveyor needs to maneuver the survey ship to sail along the planned survey line.

Single Beam Echo Sounder: An instrument that uses ultrasonic waves to measure water depths. The instrument transmits a cone-shaped sound wave beam with a certain opening angle underwater through the transducer, and the sound wave is reflected by the seabed/river bed and received by the transducer on the instrument. The echo sounder calculates the water depth at the current location based on the round-trip time of the sound waves and the underwater sound speed.

其中Di为P点与其邻域内第i个点间的距离。Inverse Distance Weighted Interpolation Algorithm: A commonly used spatial point interpolation algorithm. Let the point to be interpolated in space be P(Xp, Yp, Zp), and there are known scattered points Qi(Xi, Yi, Zi) in the neighborhood of point P, i=1, 2,....n. Use the inverse distance weighting method to interpolate the attribute value Zp of point P, Zp is the weighted average of the attribute value Zi of scattered points in the neighborhood of point P, namely:

where Di is the distance between point P and the i-th point in its neighborhood.

Underwater topographic survey navigation and acquisition software: The navigation acquisition software used in the underwater topographic survey system runs on the computer and receives the measurement raw data sent by the underwater topographic survey system, mainly including the position and water depth data, in the form of independent files. The form saves the measurement results when the survey ship sails on each planned route in the computer, and uses it with the underwater topographic survey data analysis software. At present, the commonly used underwater topographic survey and navigation acquisition software in our country are: hydrographic survey, navigation and acquisition system and HYPACK navigation and acquisition system.

Host computer: a computer installed with underwater terrain surveying, navigation and acquisition software, with multiple serial interfaces, capable of accepting data sent by echo sounders and satellite locators.

Sea state level: Also known as sea state level, it mainly refers to the wind and waves on the water surface and the undercurrent in the water. The wind and waves on the water surface will cause the measurement ship to sway in the left and right directions (rolling) or the front and rear directions (pitch), which will cause the sound beam emitted by the sounder fixed on the measurement ship to deviate from the correct direction, and it is impossible to obtain correct measurements. result. my country stipulates that the sea state level is divided into 10 levels. The wave height of level 0 is 0 meters, the sea surface is calm, and the roll angle and pitch angle of ordinary survey ships are both 0; The roll angle of the boat can reach 15 degrees and the pitch angle can reach 10 degrees. When conducting underwater topographic surveys, in order to ensure the measurement quality, it is generally required that the sea state level is less than 3; when the sea state level is greater than 3, a large number of invalid depth points will appear in the measurement results.

Measurement raw data: measurement records output from echo sounders, GPS, etc. The echo sounder outputs the measurement results through the serial port, and the format of the results is specified by the echo sounder manufacturer, which is generally given in the echo sounder technical manual. The GPS outputs the measurement results in the common NAME 0183 format through the serial port.

Positioning signal with time delay: When positioning is performed according to the signal transmitted by the GPS satellite, it takes about △T time from the locator receiving the satellite signal to the locator outputting the positioning result, (△T can generally reach 0.1-0.5S). Since the surveying vessel is always in motion when surveying at sea, the positioning signal received by the underwater terrain surveying, navigation and acquisition system corresponds to the position of the surveying vessel before the △T time during underwater topographic surveying. This phenomenon is called is the time delay of the positioning signal.

Underwater sound speed profile: The underwater sound speed profile refers to the sound speed at different depths from the sea surface. Affected by factors such as underwater temperature, salinity, and pressure, the speed of sound underwater changes with the change of water depth. In seawater, the range of underwater sound speed is about 1400-1700 m/s.

Tidal Harmonic Constant: The average amplitude and retardation angle of each subtidal decomposed from the measured tidal data. Also known as subtidal harmonic constant. referred to as the harmonic constant. After the tidal harmonic constant is calculated, the ocean tide can be predicted, the type of tide can be judged and the depth reference level of the bathymetric measurement can be calculated through the tidal prediction algorithm.

Tide forecasting algorithm: Ocean tidal phenomena can be regarded as a series of imaginary celestial bodies with different periods of sub-tidal superposition. The tidal height expression for each subtidal can be derived using the lunar equilibrium tidal height formula and the solar equilibrium tidal height formula:

h=Rcos[ωt+(Vo+U)]

where h is the subtidal tidal height; R is the theoretical amplitude of the subtidal (that is, the half-tidal range); ω is the angular velocity of the subtidal; when t is the longitude of the station, ωt is the phase angle of the time measurement; Vo+U is the astronomical initial phase angle of the ebb tide, which is calculated at 0:00 Green Mean solar time on January 1 every year.

According to the equilibrium tide theory, the high tide of any partial tide should occur at the upper (lower) mid-heaven moment of the imaginary celestial body, that is, when the phase angle [ωt+(Vo+U)] = 0, due to seabed friction, seawater inertia and other reasons, nearshore The high tide of the actual tides occurs some time after the Moon's (lower) Midheaven (i.e., the high tide gap). To obtain the tidal height at a certain time in a certain place, a correction angle K needs to be added, that is, it is assumed that the phase angle of each sub-tidal has a K value lag, that is, the actual tidal climax is behind the equilibrium tidal climax. K/ωh. K is called the local retardation angle or retardation angle. The above formula should be:

h=Rcos[ωt+(Vo+U)－K]

In the formula, R is a variable, and if it is replaced by a multi-year average (average amplitude), R=fH. f is the amplitude correction value of the subtidal, called node factor or amplitude factor; f is a function of time, usually the middle time of a year, that is, 12:00 on July 2 in Green (0:00 in leap years), and is calculated year by year for each subtidal . [ωt+(Vo+U)－K] is the tidal phase angle, which is expressed by the local time of the longitude where the station is located (for the conversion of Green Time, District Time, and Local Time, see Time, District Time System), the tidal height of the tidal tide is The final expression is:

h=fHcos[ωt+(Vo+U)－K]

That is, the subtidal tidal height h at a certain time t in a certain place can be calculated from the H and K of each subtidal, and H and K are the harmonic constants.

To determine the tidal height according to the harmonic constant, 4 diurnal, 4 semi-diurnal, and 3 shallow water tides, totaling 11 tidal tides, are usually used for observation, and a cosine curve is drawn for each tidal tide, h=Rcos(ωt- Q), R and Q are the actual amplitude and retardation angle, and the superimposed curve can reflect the complex actual tidal process. The tidal harmonic constants vary from place to place, but are constant for a fixed station.

Tide observation: Tide observation is often called water level observation, also known as tide gauge. The purpose of tidal observation is to understand the local tidal properties, apply the obtained tidal observation data, calculate the tidal harmonic constant, mean sea level, depth datum, tidal forecast, and provide water level corrections at different times of measurement, etc. It is used in military, transportation, aquatic products, surveying and mapping and other departments. Tide observations usually record the tidal value at a certain moment as the information for tidal correction. In the two hours before and after the high tide and low tide, the recording time interval is shorter, usually every 10 minutes. At low tide, the recording time interval can be extended appropriately. The most commonly used means of tidal observation in underwater topographic surveying at sea is to manually record the tidal height by means of a water gauge erected on the seashore.

The beneficial effects of the present invention are: the simulated underwater terrain measurement signal generated by the simulator provides users with a realistic water depth measurement simulated environment and simulated measurement instruments, which is convenient for the operator to perform simulated measurement on the survey area, and the simulated measurement results can be used for general purposes. In addition, scientific research institutions can also verify the underwater terrain data processing algorithm according to the simulated measurement results generated by the simulator.

Description of drawings

Fig. 1 is the working flow chart of the present invention;

Figure 2 is a schematic diagram of the simulation process of simulating the position of the surveying ship;

Figure 3 is a schematic diagram of a satellite positioning signal simulation algorithm;

Fig. 4 is the principle diagram of the simulation algorithm of water depth measurement signal;

Figure 5 is the connection structure diagram of the underwater terrain survey simulator.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the following description is made in conjunction with the accompanying drawings and specific examples of the description.

The purpose of the invention is to simulate the whole process of underwater topography measurement, which can operate and simulate the navigation of the survey ship, and provide real-time data of the position of the survey ship and the water depth at the location for the upper computer installed with the underwater topography measurement, navigation and acquisition software. An underwater terrain measurement simulation method, the specific steps of which include:

Step 1: The user changes the simulated ship speed and rudder angle of the simulated measurement ship through the measurement ship simulation controller. The underwater terrain measurement simulator is controlled by the internal clock of the system according to the speed and rudder angle input from the measurement ship simulation controller. The position simulation algorithm calculates and simulates the position of the survey ship;

Step 2: The underwater terrain survey simulator generates a GPS positioning signal with a delay effect according to the position of the simulated survey ship through the positioning signal simulation algorithm, and sends the GPS positioning signal in the required format through the serial port to the user-defined positioning period. host computer;

Step 3: Under the control of the internal clock of the system, the underwater terrain measurement simulator generates a sounder sound wave emission direction corresponding to the current moment to measure the attitude of the ship according to the sea state level set by the user through the simulation algorithm of the ship attitude;

Step 4: The underwater topographic survey simulator calculates the instantaneous tidal water level according to the tidal harmonic constant stored in the database through the tide forecasting algorithm, and displays it on the screen of the underwater topographic survey simulator according to the user-defined period.

Step 5: The underwater terrain measurement simulator calculates the measurement result of the instantaneous water depth through the water depth simulation algorithm, according to the position of the simulated measurement ship, the sounder sound wave emission direction, and the basic data of the underwater terrain simulation stored in the database, through the serial port. The user-defined format and period send the instantaneous bathymetry results to the upper computer installed with the underwater topographic survey, navigation and acquisition software.

潮流方向变化速度ω，潮流方向随机扰动值Rt，模拟测量船转向灵敏度S，计算出模拟测量船在T1时刻的位置(X1,Y1)，具体算法如下：Further, the position simulation algorithm is to measure the position (X0, Y0) and the heading angle β0 of the ship at time T0, the ship speed V0 and the rudder angle α0 input by the user, the tidal current speed Vr set by the user, and the tidal current direction.

The changing speed of the tidal current direction ω, the random disturbance value Rt of the tidal current direction, the steering sensitivity S of the simulated measuring ship, and the position (X1, Y1) of the simulated measuring ship at the time T1 are calculated. The specific algorithm is as follows:

β1=(β0+V0*△t*α0*S)Mod 360;

Among them: T0 and T1 are two adjacent simulation times, T1=T0+△t, △t is the user-defined clock cycle, the default is 0.1 seconds;

The default value of steering sensitivity S is 0.5, which can be set by the user to any value between {0.1, 0.3, 0.5, 0.7, 0.9, 1.0};

The default value of the flow direction change speed ω is 0.1 degrees/second, which can be set by the user to any value in {0.1, 0.3, 0.5};

The random disturbance value Rt of the power flow direction takes a random number uniformly distributed between -2.0 degrees and +2.0 degrees.

Further, the positioning signal simulation algorithm is to generate a GPS positioning signal with a delay effect according to the delay time set by the user and the current position of the measuring ship. The specific algorithm is as follows:

Step 2.1: Define a one-way linked list to store the position of the surveying ship, each item in the linked list is the position of the surveying ship (X, Y);

Step 2.2: After each user-defined clock cycle △t, the system calculates the position X, Y of the measuring ship according to the position simulation algorithm, and inserts it into the head of the linked list;

Step 2.3: If the length of the linked list is greater than N=Td/△t, delete the last node of the linked list;

Step 2.4: The system takes out the last node of the linked list according to the positioning signal cycle set by the user, and converts the measurement ship position (X, Y) contained in it into the format required by the host computer and outputs it from serial port 1.

Further, the underwater terrain database includes a water depth data table, a tidal harmonic constant table, and an underwater sound speed profile table; wherein the water depth data table stores the underwater terrain point cloud data of the simulated survey area; the tidal harmonic constant table stores the data. It is the 11 tidal harmonic constants of the simulated survey area; the sound speed profile table stores the sound wave propagation speed at different depths of the simulated survey area. The specific structure of each data table is as follows:

(1) Water depth data sheet

(2) Table of tidal harmonic constants

(3) Underwater sound velocity profile table

Field Name type of data Remark ID Int self-incrementing ID water depth Int water depth speed of sound Decimal underwater sound speed

Further, through the tidal forecast algorithm, according to the tidal harmonic constants stored in the database, the instantaneous tidal water level is calculated and displayed on the screen of the underwater topography simulator according to a user-defined period.

Further, the measurement ship attitude simulation algorithm is to calculate the plane coordinates of the center of the seabed irradiation range of the sound wave emitted by the simulated echo sounder according to the sea state level and the simulated measurement ship position set by the user, and the specific algorithm is as follows:

Step 3.1: Define the position coordinates of the simulated survey ship as (Xc, Yc, 0), query a water depth point P with the smallest distance from the (Xc, Yc) plane from the water depth data table in the database, and take out the water depth value Zp of this point;

Step 3.2: Taking the position (Xc, Yc, 0) of the simulated surveying vessel as the origin of the coordinates, calculate the center of the seabed irradiation range of the sound wave emitted by the simulated echo sounder when the surveying vessel rolls and pitches under the influence of the waves according to the following formula position Xr, Yr, Zr;

In the formula, Roll is the roll angle of the measuring ship, and the value is a random number evenly distributed in the interval [-3*G,+3*G]; Pitch is the pitch angle of the measuring ship, and the value is the interval [-2 *G,+2*G] is a random number uniformly distributed in ;

Step 3.3: Calculate the plane position coordinates (Xcent, Ycent) of the sound wave emitted by the echo sounder in the center of the seabed irradiation area according to the following formula

Among them, Th is the tidal height at the current moment, which is calculated by the tidal prediction algorithm according to the harmonic constant in the database.

Further, the water depth simulation method is to calculate the instantaneous water depth measurement result data obtained by calculating the measurement result data of the instantaneous water depth according to the center position of the sound wave emitted by the sounder on the seabed irradiation range, the basic underwater terrain data, and the sound wave beam angle set by the user. The specific algorithm is as follows. :

Step 5.1: According to the beam angle θ set by the user, the water depth Zp at the location of the measuring ship, and the instantaneous tidal height Th, calculate the radius R=(Zp+Th)*tan(θ );

Step 5.2: Take (Xcent, Ycent) as the center to select 4 candidate points P1 (X _P1 , Y _P1 ), P2 (X _P2 , Y _P2 ), P3 (X _P3 , Y _P3 ), P4 (X _P4 , Y _P4 ) ),in:

Step 5.3: In the sounding data table of the database, retrieve all the neighborhood sounding points whose plane distance to each candidate point is less than R/2, and calculate the plane distance between the candidate point and each neighborhood sounding point, and finally pass the distance inversely proportional The weighted interpolation algorithm calculates the water depths Z1, Z2, Z3, Z4 of the four candidate points P1, P2, P3, and P4;

i＝1，2，3，4；并选取最小的一个Di作为当前位置水深值D；Step 5.4: Calculate the distance between the four candidate points and the position (Xc, Yc, 0) of the simulated echo sounder according to the plane coordinates and water depth of the four candidate points.

i=1, 2, 3, 4; and select the smallest Di as the water depth value D at the current position;

其中i对应从海面开始计算的水深层序号，m为水深D所对应的水深层序号；△Hi为第i层到第i+1层之间的距离，通过两层在数据库中对应的深度相减得到；V_i和V_i+1分别为第i层和第i+1层的水下声速；Step 5.5: According to the underwater sound speed data stored in the database, calculate the total propagation time T of the sound wave corresponding to the water depth D from transmission to reception,

Among them, i corresponds to the sequence number of the water depth calculated from the sea surface, m is the sequence number of the water depth corresponding to the water depth D; △Hi is the distance from the i-th layer to the i+1-th layer. can be obtained by subtracting; V _i and V _i+1 are the underwater sound speeds of the i-th layer and the i+1-th layer, respectively;

其中Vs是用户设定的水下平均声速。Step 5.6: Calculate Instantaneous Bathymetry Results

where Vs is the average underwater sound speed set by the user.

On the other hand, the technical solution provided by the present application is an underwater terrain measurement simulator, which includes, in its logical structure, an underwater terrain measurement simulation software, an underwater terrain simulation database, an underwater terrain measurement simulation device, and a survey ship simulation control. device.

The underwater terrain measurement simulation software is installed in the underwater terrain measurement simulation equipment to receive the ship speed and rudder angle data sent by the user through the measurement ship simulation controller, and real-time according to these data and the basic data stored in the underwater terrain simulation database Calculate the instantaneous water depth signal and satellite positioning signal, and send it to the underwater topographic survey, navigation and acquisition system through the serial port on the device;

The underwater terrain simulation database is used to provide various basic data for calculating the simulation data for the underwater terrain measurement simulation software, including the underwater terrain point cloud data of the simulated survey area and the tidal harmonic constant of the simulated survey area;

The underwater terrain measurement simulation equipment is used to install the underwater terrain measurement simulation software and the underwater terrain simulation database. A main board and a hard disk, the main board integrates CPU, memory and graphics card; the underwater terrain measurement simulation equipment is used to run the underwater terrain measurement simulation software, and provides an interface for sending data to the outside world; the liquid crystal display screen is used to display the ship speed, Heading, rudder angle, beam angle, tidal flow velocity, tidal flow direction, tidal height, simulator working status information;

The survey ship simulation controller is a standard Windows game joystick (steering wheel), which is used to provide users with a platform to manipulate the simulated survey ship, and is connected to the underwater terrain survey simulation device through a USB transmission line; The buttons on the controller can change the speed and rudder angle of the simulated measurement ship, and the parameters of the simulator can also be set through the buttons on the controller.

The technical scheme of the underwater terrain survey simulator is as follows:

As shown in FIG. 1 , the simulator includes a survey ship simulation control module, a simulated survey ship position simulation module, a simulated survey ship attitude simulation module, a tide simulation module and a water depth simulation module in software structure. Each module works together to output water depth and position data according to the period specified by the user.

When working, firstly, the water depth measurement simulator is connected with the upper computer installed with the underwater topography measurement, navigation and acquisition software through the serial port line. Then, the ship speed and rudder angle of the simulated measurement ship are generated in real time by the measurement ship simulation controller, and the simulated measurement ship is controlled to sail according to the planned survey line. The position simulation module automatically generates the corresponding GPS positioning signal according to the position of the simulated survey ship, the attitude simulation module calculates the irradiation area of the sound wave emitted by the simulated echo sounder on the seabed according to the sea state set by the user, and the tide simulation module is based on the tide stored in the database. The harmonic constant calculates the tidal height corresponding to the current moment. The water depth simulation module calculates the corresponding measured water depth according to the aforementioned simulation results, and finally sends the water depth signal and GPS signal to the navigation acquisition system at the same time to complete the water depth measurement simulation.

The functions of each software module are as follows:

(1) Measurement ship simulation control module: The main function of the measurement ship simulation control module is to maneuver and control the simulated measurement ship to move in the direction specified by the user in the simulated measurement area under certain sea conditions, and output the instantaneous position of the simulated measurement ship. The simulation principle and process of the simulated measurement ship position are shown in Figure 2.

(2) Measurement ship position simulation module: The core of the measurement ship position simulation module is to correctly reflect the set GPS signal delay time in the output simulation signal. For a survey ship in motion, the given GPS position is always delayed for a period of time, about 0.1 to 0.5 seconds, due to the computing power of the GPS device itself. The GPS signal simulation module stores the received position of the survey ship in a linked list with a fixed length in time sequence. When the signal is output every second, the delayed GPS coordinates are searched according to the linked list. The principle is shown in Figure 3.

(3) Measurement ship attitude simulation module: The main function of the measurement ship attitude simulation module is to simulate the range of the beam emitted by the echo sounder in the area irradiated by the sea under the influence of wind and waves on the sea surface. The simulator calculates the instantaneous roll angle and pitch angle of the sound wave emitted by the simulated echo sounder according to the sea state set by the user, and then calculates the range of the echo sounder's emission beam in the seabed irradiation area according to the current position of the simulated survey ship.

(4) Tide simulation module: The function of the tide simulation module is to simulate the instantaneous tidal height corresponding to the current moment. The tidal simulation module calculates the instantaneous tidal height through the tidal forecasting algorithm and the tidal harmonic constants stored in the database.

(5) Bathymetry signal simulation module: The principle of the bathymetry signal simulation module is to first determine the direction of the simulated ultrasonic beam according to the current sea state, and then calculate the beam range irradiated on the bottom of the water according to the position of the survey ship, and determine within the beam range. 4 candidate points, calculate the water depth at the position of the candidate points according to the water depth points in the neighborhood of each candidate point through the inverse distance weighted interpolation algorithm, then calculate the slant distance from each candidate point to the transducer and select the smallest one, plus The current tidal height is used as the measured water depth. The principle is shown in Figure 4.

The feature of this embodiment is that the water depth and position signals output by the depth sounder and the GPS receiver in the underwater topographic survey are simulated and generated by the underwater topographic survey simulator, and the maneuvering control of the survey ship is simulated. Specifically, it includes: (1) navigating the simulated surveying ship by manipulating the simulated surveying ship's control equipment; (2) continuously outputting the simulated surveying ship's position signal during the navigation of the simulated surveying ship through a custom algorithm; (3) using a custom algorithm to operate the simulated surveying ship Continuously output water depth signal during sailing.

An underwater terrain measurement simulator, which includes an underwater terrain measurement simulation software, an underwater terrain simulation database, an underwater terrain measurement simulation device and a survey ship simulation controller in a logical structure.

The underwater terrain measurement simulation software is installed in the underwater terrain measurement simulation equipment to receive the ship speed and rudder angle data sent by the user through the measurement ship simulation controller, and real-time according to these data and the basic data stored in the underwater terrain simulation database Calculate the instantaneous water depth signal and satellite positioning signal, and send it to the underwater topographic survey, navigation and acquisition system through the serial port on the device;

The underwater terrain simulation database is used to provide various basic data for calculating the simulation data for the underwater terrain measurement simulation software, including the underwater terrain point cloud data of the simulated survey area and the tidal harmonic constant of the simulated survey area; In order to install underwater terrain measurement simulation software and underwater terrain simulation database, the equipment includes an LCD screen, three USB ports, two serial ports and an RJ-45 network port. The equipment includes a main board and a hard disk. It integrates CPU, memory and graphics card; underwater terrain measurement simulation equipment is used to run underwater terrain measurement simulation software, and provides an interface for sending data to the outside world; LCD screen is used to display ship speed, heading, rudder angle, beam angle in real time , tidal flow rate, tidal flow direction, tidal height, and working state information of the simulator; the measurement ship simulation control device is used by the user to control the simulation measurement ship to sail according to the planned survey line; the simulation measurement ship control device is a WINDOWS game joystick in the form of a steering wheel , in the present invention, the functions of the buttons on the joystick are as follows: button 1: reduce the beam angle of the sound wave; button 2: increase the sea state level of the simulated survey area; button 3: decrease the sea state level of the simulated survey area; button 4: increase the sound wave Beam angle; Button 5: Increase the speed of the simulated survey ship; Button 6: Decrease the speed of the simulated survey boat; Button 7: Stop the simulation; Button 8: Start the simulation; Button 9: Decrease the GPS signal delay time; Button 10: Increase the GPS signal Delay time; upper button of visual helmet: increase the tidal current speed in the simulated survey area; button down of the visual helmet: decrease the tidal current speed of the simulated survey area; left button of the visual helmet: decrease the flow direction of the simulated survey area; right button of the visual helmet: increase the simulated survey area Tide direction; steering wheel left button: the rudder angle increases to port; right steering wheel button: the rudder angle increases to starboard.

During the simulation, the user changes the rudder angle of the simulated measuring vessel through the steering wheel on the controller, and sets the speed of the simulated measuring vessel through the gear lever on the controller, so as to control the simulated measuring vessel to sail along the route designed by the user. Other buttons are used to set system simulation parameters.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Those skilled in the art make some simple modifications, equivalent changes or modifications by using the technical contents disclosed above, all of which fall within the scope of the present invention. within the scope of protection of the invention.

Claims (8)

1. The underwater topography measurement simulation method is characterized by comprising the following steps:

step 1: the user changes the ship speed and rudder angle of the simulated measuring ship through the measuring ship simulation controller, and the underwater topography measuring simulator calculates the position of the simulated measuring ship through a position simulation algorithm according to the ship speed and rudder angle of the simulated measuring ship and the period defined by the user under the control of the internal clock of the system;

step 2: the underwater topography measurement simulator generates a GPS positioning signal with a delay effect according to the position of the simulated measurement ship through a positioning signal simulation algorithm, and sends the GPS positioning signal to an upper computer through a serial port according to a positioning period defined by a user;

and step 3: the underwater topography measurement simulator generates a sound wave emission direction of a depth finder corresponding to the current ship attitude measurement according to a simulation algorithm of the ship attitude measurement, sea condition levels set by a user and a period defined by the user under the control of a clock in the system;

and 4, step 4: calculating the instantaneous tide water level height by the underwater topography measurement simulator according to the tide harmonic constant stored in the database through a tide forecasting algorithm, and displaying the instantaneous tide water level height on a screen of the underwater topography measurement simulator according to a period defined by a user;

and 5: the underwater topography measurement simulator calculates the measurement result of the instantaneous water depth according to the position of the simulated measurement ship, the attitude of the simulated measurement ship and the underwater topography simulation basic data stored in the database through a water depth simulation algorithm, and sends the measurement result of the instantaneous water depth to an upper computer provided with underwater topography measurement navigation acquisition software according to a format and a period defined by a user through a serial port.

2. The underwater topography measurement simulation method according to claim 1, wherein the position simulation algorithm is based on the position (X0, Y0) of the simulated survey vessel at time T0 and a heading angle β 0, a vessel speed V0 and a rudder angle α 0 inputted by a user, a tidal current speed Vr set by the user, a tidal current direction and a direction of the tidal current

The method comprises the following steps of calculating the position (X1, Y1) of a simulated measuring ship at the time T1 by using the tidal current direction change speed omega, the tidal current direction random disturbance value Rt and the simulated measuring ship steering sensitivity S, wherein the specific algorithm is as follows:

β1＝(β0+V0*△t*α0*S)Mod 360；

t0 and T1 are two adjacent simulation moments, T1 is T0+ △ T, △ T is a clock period defined by a user, and the default time is 0.1 second;

the default value of the steering sensitivity S is 0.5, and can be set to any value between {0.1, 0.3, 0.5, 0.7, 0.9 and 1.0} by a user;

the default value of the tidal current direction change speed omega is 0.1 degree/second, and can be set to any one value of {0.1, 0.3 and 0.5} by a user;

the power flow direction random disturbance value Rt takes a random number which is uniformly distributed between-2.0 degrees and +2.0 degrees.

3. The underwater topography measurement simulation method according to claim 1, characterized in that: the positioning signal simulation algorithm is used for generating a GPS positioning signal with a delay effect according to the delay time Td set by a user and the current position of the measuring ship; the specific algorithm is as follows:

step 2.1: defining a one-way linked list to store the positions of the measuring ships, wherein each item of content in the linked list is the position (X, Y) of the measuring ship;

step 2.2, calculating the position (X, Y) of the measuring ship once by the system according to a position simulation algorithm every time the system passes a self-defined clock period △ t, and inserting the position (X, Y) into the head of the linked list;

step 2.3, if the length of the linked list is greater than N, Td/△ t, deleting the last node of the linked list;

step 2.4: the system takes out the last node of the linked list according to the positioning signal period set by the user, converts the position (X, Y) of the measuring ship contained in the last node into the format required by the upper computer and outputs the format from the serial port 1.

4. The underwater topography measurement simulation method according to claim 1, characterized in that: the database comprises a water depth data table, a tide harmonic constant table and a sound velocity profile table; the water depth data table stores underwater topography point cloud data of the simulated survey area; the tide harmonic constant table stores 11 tide harmonic constants of the simulated measuring area; the sound velocity profile table stores the sound wave propagation velocity of the simulated measuring area at different depths.

5. The underwater topography measurement simulation method according to claim 1, characterized in that: the attitude simulation algorithm of the measuring vessel is used for calculating the plane coordinate of the sound wave emitted by the analog depth finder in the center of the seabed irradiation range according to the sea state level and the position of the analog measuring vessel set by a user, and comprises the following specific algorithms:

step 3.1: defining the position coordinate of the simulated survey ship as (Xc, Yc,0), inquiring a water depth point P with the minimum distance to the (Xc, Yc) plane from a water depth data table in a database, and taking out a water depth value Zp of the point;

step 3.2: taking the position (Xc, Yc,0) of the simulated measuring ship as a coordinate origin, and calculating the central positions Xr, Yr and Zr of sound waves emitted by the simulated depth finder in the seabed irradiation range when the measuring ship is influenced by sea waves and rolls and pitches according to the following formula;

in the formula, Roll is the Roll angle of the measuring ship, and takes the value of a random number uniformly distributed in an interval [ -3 × G, +3 × G ]; pitch is the Pitch angle of the measuring ship, and takes the value of a random number uniformly distributed in an interval [ -2 × G, +2 × G ]; g is the sea state level set by the user, the value is any one number of [0,1,2,3,4 and 5], and the default value is 0;

step 3.3: calculating the plane position coordinates (Xcent, Ycent) of the sound waves emitted by the depth finder in the center of the seabed irradiation area according to the following formula;

and Th is the height of the tide at the current moment, and is calculated by a tide forecasting algorithm according to a harmonic constant in the database.

6. The underwater topography measurement simulation method according to claim 1, characterized in that: the water depth simulation method is characterized in that instantaneous water depth measurement result data obtained by measurement is calculated according to the central position of a sound wave emitted by a depth finder in a seabed irradiation range, underwater topography basic data and a sound wave beam angle set by a user, and the specific algorithm is as follows:

step 5.1: according to a beam angle theta set by a user, the water depth Zp at the position of the measuring ship and the instantaneous tide height Th, calculating the radius R (Zp + Th) tan (theta) of the irradiation range of the sound wave emitted by the analog depth finder on the seabed;

step 5.2: selecting 4 candidate points P1 (X) with (Xcent, Ycent) as the center_P1，Y_P1)，P2(X_P2，Y_P2)，P3(X_P3，Y_P3)，P4(X_P4，Y_P4) Wherein:

step 5.3: respectively searching all neighborhood water depth points with the plane distance smaller than R/2 from each candidate point in a water depth data table of the database, calculating the plane distance between each candidate point and each neighborhood water depth point of the candidate point, and finally calculating the water depths Z1, Z2, Z3 and Z4 of the four candidate points P1, P2, P3 and P4 through an inverse distance weighted interpolation algorithm;

step 5.4: respectively calculating the positions of the four candidate points and the analog depth finder according to the plane coordinates and the water depth of the four candidate pointsDistance between (Xc, Yc,0)

i is 1,2,3, 4; selecting the smallest Di as a water depth value D of the current position;

step 5.5: calculating the total propagation time T from emission to reception of the sound wave corresponding to the water depth D according to the underwater sound velocity data stored in the database,

wherein i corresponds to the sequence number of the deep water layer calculated from the sea surface, m is the sequence number of the deep water layer corresponding to the depth D, △ Hi is the distance between the ith layer and the (i + 1) th layer and is obtained by subtracting the corresponding depths of the two layers in the database, and V_iAnd V_i+1The underwater sound velocities of the ith layer and the (i + 1) th layer are respectively;

step 5.6: calculating instantaneous bathymetry

Where Vs is the user-set underwater average speed of sound.

7. The underwater topography measurement simulator is characterized in that:

the underwater topography measurement simulator comprises underwater topography measurement simulation software, an underwater topography simulation database, underwater topography measurement simulation equipment and a measuring ship simulation controller on a logical structure;

the underwater topography measurement simulation software is installed in the underwater topography measurement simulation equipment and used for receiving ship speed and rudder angle data sent by a user through a ship measurement simulation controller, calculating an instantaneous water depth signal and a satellite positioning signal in real time according to the data and basic data stored in an underwater topography simulation database, and sending the instantaneous water depth signal and the satellite positioning signal to an underwater topography measurement navigation acquisition system through a serial port on the equipment;

the underwater topography simulation database is used for providing various basic data of calculation simulation data for underwater topography measurement simulation software, and the basic data comprises underwater topography point cloud data of a simulation measuring area, a tidal harmonic constant of the simulation measuring area and underwater sound velocity profile data of the simulation measuring area;

the underwater topography measurement simulation device is used for installing underwater topography measurement simulation software and an underwater topography simulation database, the device comprises a liquid crystal display screen, three USB interfaces, four serial interfaces and an RJ-45 network interface, the device internally comprises a mainboard and a hard disk, and a CPU, a memory and a display card are integrated on the mainboard; the underwater topography measurement simulation equipment is used for operating underwater topography measurement simulation software and providing an interface for sending data to the outside; the liquid crystal display is used for displaying the ship speed, the course, the rudder angle, the beam angle, the tidal current flow speed, the tidal current flow direction, the tidal height and the simulator working state information in real time;

the measuring vessel simulation manipulator is used for providing equipment for operating the simulation measuring vessel for a user and is connected to the underwater topography measuring simulation equipment through a USB transmission line; the user changes the speed and rudder angle of the simulated survey ship through the buttons on the survey ship simulated controller, and sets various parameters of the simulator through the buttons on the controller.

8. The underwater topography measurement simulator of claim 7, wherein: the measuring ship simulation manipulator is a rocker, a steering wheel or a keyboard.

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