阅读说明：本技术 一种海面小型目标升沉运动测量方法 (Method for measuring heave motion of small sea-surface target ) 是由 徐晓苏 张海旭 于 2021-01-30 设计创作，主要内容包括：本发明公开了一种海面小型目标升沉运动测量方法,其主要目的在于解决对海面小型目标回收之前,获取目标升沉运动轨迹以估计海况信息的问题。本发明的主要步骤包括：SINS和GNSS组合结果的求解、升沉运动轨迹的提取、波高以及有效波高的计算、波面时间历程的模拟、SINS和波面时间历程的组合计算。本发明在GNSS有效时,从SINS和GNSS的组合结果中提取升沉运动轨迹,当GNSS失效时,从前一个时间段的升沉运动轨迹中提取有效波高数据,结合波浪频谱模拟出下一个时间段内的波面时间历程,将SINS和模拟值组合计算,并提取目标升沉运动轨迹。本发明利用波浪谱模拟波面时程的方法,解决了SINS在GNSS长时间缺失的情况下导致的天向发散问题,在估计海况信息方面具有重要参考价值。(The invention discloses a method for measuring the heave motion of a small sea surface target, which mainly aims to solve the problem of acquiring a target heave motion track to estimate sea condition information before recovering the small sea surface target. The method mainly comprises the following steps: solving a combined result of the SINS and the GNSS, extracting a heave motion track, calculating wave height and effective wave height, simulating wave surface time course, and performing combined calculation of the SINS and the wave surface time course. When the GNSS is effective, the heave motion track is extracted from the combined result of the SINS and the GNSS, when the GNSS is invalid, effective wave height data is extracted from the heave motion track in the previous time period, the wave surface time history in the next time period is simulated by combining a wave frequency spectrum, the SINS and the simulation value are combined and calculated, and the target heave motion track is extracted. The method for simulating the wave surface time course by using the wave spectrum solves the problem of day-wise divergence caused by SINS under the condition of long-time loss of GNSS, and has important reference value in the aspect of estimating sea state information.)

1. A method for measuring heave motion of a small sea surface target is characterized by comprising the following steps:

step 1: judging whether the GNSS is effective or not, if so, jumping to the step 2, otherwise, jumping to the step 4;

step 2: acquiring SINS and GNSS parameters, performing combined operation, and calculating a natural motion track under a northeast coordinate system;

and step 3: calculating the heave motion trail of the sea surface target according to the sky motion trail calculated in the step 2, and jumping to the step 1;

and 4, step 4: intercepting a heave motion track in an adjacent time period, calculating a wave height sequence and calculating an effective wave height;

and 5: simulating the wave surface time history in the next time period according to the effective wave height and the wave frequency spectrum;

step 6: combining parameters of the SINS and the simulated wave surface time course for operation, and calculating a natural motion track under a northeast coordinate system;

and 7: and (4) calculating the heave movement locus of the sea surface target according to the sky movement locus calculated in the step 6, and jumping to the step 1.

2. The method for measuring heave motion of a small sea surface target according to claim 1, wherein the step 3 is specifically as follows:

selecting the data of the sky-direction motion trail from the combined result of the SINS/GNSS, and recording the data as H_i(t), i is 1,2,3, …, N, equally dividing the data into a plurality of data segments, and taking one of the data segments as h_i(t)，i＝1,2,3,…,n，n<And N, establishing a rectangular coordinate system by taking the displacement h as a vertical axis and the time t as a horizontal axis, and performing discrete pointing on data segments in the coordinate system by using a least square methodAnd (4) line fitting to obtain a straight line h which is at + b, the straight line is regarded as a virtual horizontal line of the data segment, the distances from all the discrete points to the straight line are calculated and are recorded as d_i(t), i is 1,2,3, …, n, wherein if the discrete point is above the straight line, the distance is taken as a positive value, and the wave path is regarded as a wave path higher than the horizontal line; if the discrete point is located below the straight line, taking the distance as a negative value, and regarding the distance as a wave path lower than the horizontal line; to d_i(t) average and d_a. Under ideal conditions, the wave surface course can be regarded as the motion track of a synthetic wave composed of infinite sine waves, and the mean value d thereof_aShould be zero, but in engineering practice, due to the presence of errors, d_aIs not zero, and to eliminate the mean error, let D_i(t)＝d_i(t)-d_aThen, the heave motion track of the sea surface object with the horizontal plane as the reference, namely D, is obtained from the data segment_iAnd (t), processing methods of other data segments and the like, wherein the heave movement tracks of all the data segments form the day-wise movement process of the sea surface target.

3. The method for measuring heave motion of a small sea surface target according to claim 1, wherein the step 4 is specifically as follows:

selecting heave motion data in a period of time before GNSS failure, wherein the period of data comprises a plurality of wave path information (D)₁、D₂、D₃…) and short duration, and is recorded as

D(t)＝{D₁ D₂ D₃ … D_m}

Order to

D_i(t)＝{U₁(t) U₂(t) ... U_n(t)}

Wherein n < m, and

wherein, the elements in each U (t) have the same sign, and the elements in two adjacent U (t) have different signs, if U is₁The element in (t) is negativeNumber, after discarding the set of elements, the wave height of each interval is represented as

W_i＝max(U_2i(t))-min(U_2i+1(t)), i ═ 1,2,3, …, q, and q<n/2

If U is present₁The elements in (t) are positive signs, and after discarding the group of elements, the wave height is expressed as the lower zero crossing method

W_i＝max(U_2i+1(t))-min(U_2i(t)), i ═ 1,2,3, …, q, and q<n/2

And all elements in the wave height array are arranged according to the numerical value in a descending order, and the average wave height of the first one third of large waves is taken as the effective wave height.

4. The method for measuring heave motion of a small sea surface target according to claim 1, wherein the step 5 is specifically as follows:

the wave spectrum obtained by substituting the effective wave height value into the P-M frequency spectrum is taken as a target spectrum to simulate the time history of the irregular wave surface, wherein the P-M frequency spectrum is taken as

Where ω is the circular frequency, H_sThe effective wave height is divided into M parts, and the wave surface time course is expressed as

Wherein m is₀Is the zero-order moment of the frequency spectrum,is a random initial phase, in addition to

Wherein, ω is_iIs the boundary frequency, so far, the wave surface time course of any time length and sampling frequency can be simulated according to the requirements and is recorded as

η(t)＝{η₁ η₂ η₃ … η_n}

Namely, the method can be used for combined calculation with the SINS.

5. The method for measuring heave motion of a small sea surface target according to claim 1, wherein the calculation method of step 7 is the same as that of step 3.

Technical Field

The invention belongs to the technical field of marine small target state measurement, and particularly relates to a method for measuring the heave motion of a sea surface small target by using SINS/GNSS combined operation and considering GNSS signal loss.

Background

With the gradual depletion of land resources, the development pace of the oceans by human beings is accelerated, and more detection devices are put into the oceans. As a final and most important part of the exploration marine mission, the recycling of the equipment may determine the success or failure of the entire project. The recovery work of the marine exploration equipment after floating out of the water surface is greatly influenced by the marine state. From the experience of engineering practice, the recovery work of the equipment is often carried out under good sea conditions, since the shaking of the vessel under severe sea conditions can seriously threaten the operational safety of the crane. Missing the best recovery time may result in the equipment losing connection due to the depletion of electrical energy, disappearing in a stranded sea. The wave size is an important factor influencing the recovery work, and wave height data extracted from the heave movement of the target can be used for estimating sea state information of the environment where the target is located, so that an important reference is provided for reasonable arrangement of the recovery work.

As a classical combined mode, the SINS/GNSS combined navigation technology can not only provide high positioning accuracy, but also ensure very high real-time performance of high-frequency sampling of the SINS, and the GNSS has an obvious effect on limiting SINS divergence. In engineering practice, after some small-sized equipment floats out of the water surface, because a GNSS antenna in a cabin body is close to the water surface, satellite signals are easily influenced by waves, and even the interruption of the GNSS signals occurs for several minutes under the condition of medium waves with slightly poor sea conditions. The frequent absence of GNSS signals under severe sea conditions will result in that the measurements of the SINS/GNSS combination are no longer reliable. In the aspect of resolving the motion locus in the direction of the day, the simulation wave surface process is helpful for solving the problem of divergence in the direction of the day. The wave is a random phenomenon with stationarity and ergodicity, and the overall characteristics of the sea wave can be represented by using the wave records of a few measuring points. In engineering practice, after obtaining parameters such as effective wave height and period of waves, a series of time histories of irregular wave surfaces are obtained by a simulated target spectrum method. Examples of the wave spectrum that can be used for the target spectrum simulation include Neumann spectrum, Bretschneider spectrum, Mitsuyasu spectrum, ISSC spectrum, P-M spectrum, Jonswap spectrum, and Venturi spectrum. The single parameter spectrum P-M spectrum only has one input parameter, namely the effective wave height, and is very suitable for being applied to combined operation with SINS. The simulated wave surface time history is used for filling up the combined operation after the GNSS is absent, and has important research significance in the aspect of measuring the heaven-wise heave movement.

Disclosure of Invention

In order to solve the problems, the invention discloses a method for measuring the heave motion of a small sea surface target, which is suitable for judging the sea condition information of the environment where the target is located by measuring the heave motion track of the target before the remote sea surface target is recovered, and provides reference for the reasonable arrangement of the recovery work of workers.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for measuring heave motion of a small sea surface target comprises the following steps:

step 1: judging whether the GNSS is effective or not, if so, jumping to the step 2, otherwise, jumping to the step 4;

step 2: acquiring SINS and GNSS parameters, performing combined operation, and calculating a natural motion track under a northeast coordinate system;

and step 3: calculating the heave motion trail of the sea surface target according to the sky motion trail calculated in the step 2, and jumping to the step 1;

and 4, step 4: intercepting a heave motion track in an adjacent time period, calculating a wave height sequence and calculating an effective wave height;

and 5: simulating the wave surface time history in the next time period according to the effective wave height and the wave frequency spectrum;

step 6: combining parameters of the SINS and the simulated wave surface time course for operation, and calculating a natural motion track under a northeast coordinate system;

and 7: and (4) calculating the heave movement locus of the sea surface target according to the sky movement locus calculated in the step 6, and jumping to the step 1.

Further, the step 3 specifically includes:

selecting the data of the sky-direction motion trail from the combined result of the SINS/GNSS, and recording the data as H_i(t), i ═ 1,2, 3. Equally dividing the data into a plurality of data segments, and taking one of the data segments as h_i(t)，i＝1,2,3,...,n，n<And N is added. Taking the displacement h as a vertical axis and the time t as a horizontal axis, establishing a rectangular coordinate system, fitting discrete points of a data segment in the coordinate system by using a least square method to obtain a straight line h which is at + b, wherein the straight line can be regarded as a virtual horizontal line of the data segment, calculating the distance from all the discrete points to the straight line and is marked as d_i(t), i ═ 1,2, 3.., n, where discrete points are locatedTaking the distance above the straight line as a positive value, and regarding the distance as a wave path higher than the horizontal line; if the discrete point is located below the straight line, the distance is taken as a negative value, and the wave path is considered to be lower than the horizontal line. To d_i(t) average and d_a. Under ideal conditions, the wave surface course can be regarded as the motion track of a synthetic wave composed of infinite sine waves, and the mean value d thereof_aShould be zero, but in engineering practice, due to the presence of errors, d_aIs not zero, and to eliminate the mean error, let D_i(t)＝d_i(t)-d_aThen, the heave motion track of the sea surface object with the horizontal plane as the reference, namely D, is obtained from the data segment_i(t) of (d). And the processing method of other data fragments is similar to the other methods. The heave motion trajectories of all the data segments form the heaven-directional motion history of the sea surface target.

Further, the step 4 specifically includes:

selecting heave motion data in a period of time before GNSS failure, wherein the period of data comprises a plurality of wave path information (D)₁、D₂、D₃...), and of short duration (in minutes), is noted as

D(t)＝{D₁ D₂ D₃ ... D_m}

Order to

D_i(t)＝{U₁(t) U₂(t) ... U_n(t)}

Wherein n < m, and

U₁(t)＝{D₁ D₂ ... D_j},

U₂(t)＝{D_j+1 D_j+2 ..., D_j+k},

...

U_n(t)＝{D_l D_l+1 ... D_m}

wherein, the elements in each U (t) have the same sign, and the elements in two adjacent U (t) have different signs. If U is present₁The element in (t) is a negative sign, and after discarding the group of elements, the wave height of each interval can be expressed as the upper zero crossing method

W_i＝max(U_2i(t))-min(U_2i+1(t)), i ═ 1,2, 3.., q, and q ═ q<n/2

If U is present₁The elements in (t) are positive signs, and after discarding the set of elements, the wave height can be expressed as a lower zero crossing method

W_i＝max(U_2i+1(t))-min(U_2i(t)), i ═ 1,2, 3.., q, and q ═ q<n/2

And all elements in the wave height array are arranged according to the numerical value in a descending order, and the average wave height of the first one third of large waves is taken as the effective wave height.

Further, the step 5 specifically includes:

the wave spectrum obtained by substituting the effective wave height value into the P-M frequency spectrum is taken as a target spectrum to simulate the time history of the irregular wave surface, wherein the P-M frequency spectrum is taken as

Where ω is the circular frequency, H_sThe effective wave height is divided into M parts, and the wave surface time course can be expressed as

Wherein m is₀Is the zero-order moment of the frequency spectrum,is a random initial phase, in addition to

Wherein, ω is_iIs the boundary frequency. So far, the wave surface time course with any time length and sampling frequency can be simulated according to the requirements and is recorded as

η(t)＝{η₁ η₂ η₃ ... η_n}

Namely, the method can be used for combined calculation with the SINS.

The invention has the beneficial effects that:

according to the method for measuring the heave motion of the small sea surface target, the P-M wave frequency spectrum is adopted to simulate the wave surface course, the problem of day-direction divergence caused by GNSS loss can be solved, and the system can continuously and stably output the heave motion track for estimating the sea condition information under the condition that the GNSS is discontinuous caused by severe sea conditions. Compared with the conventional frequency domain analysis method using fast Fourier transform, the method has higher real-time performance, does not need to intercept data at fixed time intervals for calculation, and also avoids the distortion problem caused by frequency domain analysis.

Drawings

FIG. 1 is a computational schematic of the present invention;

FIG. 2 is a schematic diagram of extracting a wave front history from a combined result;

FIG. 3 is a schematic diagram of calculating wave height by the upper zero crossing method;

FIG. 4 is a comparison graph of results using simulated wavefront combination and not using their participation combination;

fig. 5 is a wave height statistical chart of the calculation result of this method.

Detailed Description

The present invention will be further illustrated with reference to the accompanying drawings and specific embodiments, which are to be understood as merely illustrative of the invention and not as limiting the scope of the invention.

After the ocean exploration equipment floats out of the water surface, the heave movement of the ocean exploration equipment can reflect the sea condition information of the environment where the ocean exploration equipment is located to a certain extent. As shown in fig. 1, the method for measuring heave motion of a small sea-surface target according to the present invention comprises the following steps:

1) establishing a model of an integrated navigation system

Taking the effective situation of the GNSS signals as an example, the integrated navigation system model based on the kalman filter is established as follows:

wherein the content of the first and second substances,

wherein phi is_z、φ_y、φ_zIn order to be the inertial navigation misalignment angle,for velocity errors, δ λ, δ L, δ h are position errors, ε_x、ε_y、ε_zIn order to make the gyro drift in a random constant value,a random constant bias value is applied to the accelerometer.

The measurement vector Z is the difference between the measurements of the SINS and the GNSS in the sky direction, i.e.

Z＝[h_SINS-h_GNSS]

Matrix W is the measurement noise of the gyroscopes and accelerometers, and matrix V is the measurement noise of the GNSS in the altitude.

2) Extracting data from a SINS/GNSS combination

In the case that the GNSS signals are valid, the combined result of the SINS and GNSS is used as the data source of the heave motion trajectory. Recording the selected data of the motion trail in the direction of the sky as H_i(t), i ═ 1,2, 3. Equally dividing the data into a plurality of data segments, and taking one of the data segments as h_i(t)，i＝1,2,3,...,n，n<And N is added. Taking the displacement h as the vertical axis and the time t as the horizontal axis, a rectangular coordinate system is established, as shown in fig. 2. T in the figure₁And t₂Is the corresponding time in the target's natural motion trajectory, vt₁And vt₂Is its time relative to the virtual horizon. And fitting discrete points of the data segments in the coordinate system by using a least square method, namely solving the optimal value of the following objective function:

J(θ)＝(B-Tθ)^T(B-Tθ)

wherein the content of the first and second substances,

B＝[h₁ h₂ ... h_n]^T

n is the number of measurements in the data segment.

The obtained straight line h is at + b, which is the virtual horizontal line. The distances from all the discrete points to the straight line are calculated, and are denoted by di (t), i is 1,2, 3. And d, (t) averaging di (t) and di (t) -da, so that the heave motion trajectory of the sea surface target with the horizontal plane as a reference, namely di (t), is obtained from the data segment. And the processing method of other data fragments is similar to the other methods. The heave motion trajectories of all the data segments form the heaven-directional motion history of the sea surface target.

3) Extracting data from a combination of SINS and simulated wave surface histories

When the GNSS fails, the simulation of the wave surface time history is required for the combination of the SINS in the day-wise displacement. The method comprises the following steps:

step 1: calculating effective wave height

Heave motion data is selected for a period of time before GNSS failure, the period of data contains sufficient wave height information and is short in duration (in the order of minutes). Is marked as

D(t)＝{D₁ D₂ D₃ ... D_m}

Order to

D(t)＝{U₁(t) U₂(t) ... U_n(t)}

Wherein n < m, and

U₁(t)＝{D₁ D₂ ... D_j},

U₂(t)＝{D_j+1 D_j+2 ..., D_j+k},

...

U_n(t)＝{D_l D_l+1 ... D_m}

wherein, the elements in each U (t) have the same sign, and the elements in two adjacent U (t) have different signs. If U is present₁The elements in (t) are negative signs, and after discarding the set of elements, the wave height of each interval can be expressed as the zero crossing point method shown in FIG. 3

W_i＝max(U_2i(t))-min(U_2i+1(t)), i ═ 1,2, 3.., q, and q ═ q<n/2

If U is present₁The elements in (t) are positive signs, and after discarding the set of elements, the wave height can be expressed as a lower zero crossing method

W_i＝max(U_2i+1(t))-min(U_2i(t)), i ═ 1,2, 3.., q, and q ═ q<n/2

And all elements in the wave height array are arranged according to the numerical value in a descending order, and the average wave height of the first one third of large waves is taken as the effective wave height.

Step 2: analog wave surface course

The wave spectrum obtained by substituting the effective wave height value into the P-M frequency spectrum is taken as a target spectrum to simulate the time history of the irregular wave surface, wherein the P-M frequency spectrum is taken as

Where ω is the circular frequency, H_sThe effective wave height is divided into M parts, and the wave surface time course can be expressed as

Wherein m is₀Is the zero-order moment of the frequency spectrum,is a random initial phase, in addition to

Wherein, ω is_iIs the boundary frequency. So far, the wave surface time course with any time length and sampling frequency can be simulated according to the requirements and is recorded as

η(t)＝{η₁ η₂ η₃ ... η_n}

Namely, the method can be used for combined calculation with the SINS.

And step 3: SINS and analog value combining operation

In a combined model using simulated wavefront history data and SINS, the measurement equation is

Z_s＝HX+V_s

Wherein, V_sRepresenting the error of the simulated wave surface course data, the measurement vector is

Z_s＝[h_SINS-η(t)]

The method of combining the elevation of the analog wave and the SINS is adopted, and the defect of GNSS interruption under severe sea conditions is overcome. And can provide real-time output with high dynamic performance.

And 4, step 4: extracting heave motion information

The heave motion information extraction method for the combined result is the same as the method shown in fig. 2.

And when the GNSS is effective, the combination of the GNSS and the SINS is used, and the heave trajectory of the target is extracted from the day-wise displacement of the combined result. When the GNSS is invalid, the simulated wave surface course and the SINS are combined, and the heave track of the target is extracted from the combined result. By reciprocating in this way, the heave information of the target in the environment can be continuously output, and a real-time sea state information reference is provided for the working personnel of the recovery equipment.

Example 1

In this embodiment, the GNSS interruption time is set to a random value smaller than 30 minutes, the connection time is set to a random value smaller than 5 seconds, the interruption and the continuation last for 10 hours, and the heave trajectory of the target is calculated by using the above method. The combined fraction of a certain GNSS outage time is intercepted and the result is shown in fig. 4. The average wave height and the effective wave height of the time period are calculated every five minutes, and as shown in fig. 5, the simulation result verifies the effectiveness of the invention.

The technical means disclosed in the invention scheme are not limited to the technical means disclosed in the above embodiments, but also include the technical scheme formed by any combination of the above technical features.