CN115636063B - A method and device for high-precision real-time identification of ship propeller shaft thrust - Google Patents
A method and device for high-precision real-time identification of ship propeller shaft thrust Download PDFInfo
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- CN115636063B CN115636063B CN202211390047.4A CN202211390047A CN115636063B CN 115636063 B CN115636063 B CN 115636063B CN 202211390047 A CN202211390047 A CN 202211390047A CN 115636063 B CN115636063 B CN 115636063B
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Abstract
本发明公开了一种船舶螺旋桨轴推力高精度实时辨识方法与装置，包括如下步骤：加工测量装置并安装在转轴上；获取测量装置纵向应变及环境温度，构建推力、温度与应变的第一等式；对第一等式求导并按时间离散得到第二等式，基于第二等式得到系统矩阵方程与观测方程；基于矩阵方程完成第k个时间步推力状态预测，基于观测方程完成推力状态估计；将时间递推至第k+1个时间步，重复状态预测与状态估计，最终获得推力动态过程。本发明具有较强抗干扰能力，可补偿环境温度变化引起的热变形误差，能在强干扰噪声中保持较高测量精度。此外，本发明中应变片贴在测量装置上，可在实验室中标定应变片灵敏度系数，从而消除应变片粘贴方式、胶水种类等外因影响。
The present invention discloses a method and device for high-precision real-time identification of the thrust of a ship propeller shaft, comprising the following steps: processing a measuring device and installing it on a rotating shaft; obtaining the longitudinal strain of the measuring device and the ambient temperature, and constructing a first equation of thrust, temperature and strain; deriving the first equation and discretizing it in time to obtain a second equation, and obtaining a system matrix equation and an observation equation based on the second equation; completing the thrust state prediction of the kth time step based on the matrix equation, and completing the thrust state estimation based on the observation equation; recursing the time to the k+1th time step, repeating the state prediction and state estimation, and finally obtaining the thrust dynamic process. The present invention has a strong anti-interference ability, can compensate for the thermal deformation error caused by the change of ambient temperature, and can maintain a high measurement accuracy in strong interference noise. In addition, in the present invention, the strain gauge is attached to the measuring device, and the strain gauge sensitivity coefficient can be calibrated in the laboratory, thereby eliminating the influence of external factors such as the strain gauge pasting method and the type of glue.
Description
Technical Field
The invention belongs to the field of ship power, and particularly relates to a high-precision real-time identification method and device for thrust of a ship propeller shaft.
Background
The thrust of the ship propulsion system at each rotating speed is accurately monitored on line in real time, so that accurate data requirements can be provided for ship rapidness prediction, sailing state monitoring, ship-machine-oar optimization matching and the like, and the method has important engineering significance. However, the technical bottleneck faced at present is mainly that the propeller thrust is difficult to accurately monitor in real time under the interference environment of a real ship, and the main reason is that weak deformation signals generated by the thrust on a shafting are extremely easy to be submerged by noise such as thermal deformation of a cabin, mechanical noise, electromagnetic noise, shafting vibration and the like, and weak thrust signals are difficult to identify from measured deformation signals.
Several patents have been presented to address thrust testing related patents, including methods and apparatus.
The method is a method for analyzing the stress state of the rotating shaft of the hydraulic generator. The method comprises the following steps of S1, establishing a finite element model according to a test rotating shaft, S2, verifying the correctness of the finite element model through theoretical calculation, S3, arranging a strain gauge on the shaft, testing the axial equal stress of the rotating shaft, S4, applying boundary conditions in the finite model to enable the calculated stress to be equal to the test stress, S5, establishing the relation between the maximum stress value of the rotating shaft and the field stress test value through analyzing the calculation result and the field stress test result of the finite element model, and achieving the purpose of directly evaluating the service life and the safety state of the rotating shaft through the field stress test result.
The device is a model driving and thrust and torque testing system of an underwater nacelle or rudder propeller propulsion device. The patent includes a drive module, a measurement module, and a transmission module. The driving module adopts a direct current motor, a motor rotating shaft is connected with the measuring module, and the other end of the measuring module is connected with the propeller. Strain gages on the measurement module may measure the strain produced by the thrust. The transmission module transmits signals and input voltage of the strain gauge in a non-contact coupling mode.
The axial force testing device for the thrust rod of the commercial vehicle. The patent comprises a thrust rod, a strain gauge and a data acquisition instrument. The strain gauge is fixedly arranged on the surface of the thrust rod parallel to the axis of the thrust rod through an adhesive layer, and is electrically connected with a data acquisition instrument which acquires data of the strain gauge.
However, the above patents have the main defect of low anti-interference capability, and the technical problem of low test precision in the environments of temperature change and strong interference noise.
Disclosure of Invention
The invention aims to provide a high-precision real-time identification method and device for thrust of a ship propeller shaft, which are used for solving the technical problem of low measurement precision caused by environmental temperature change and strong interference noise.
In order to solve the problems, the technical scheme of the invention is as follows:
a high-precision real-time identification method for the thrust of a ship propeller shaft comprises the following steps:
Acquiring strain signals of at least 2 strain gauges mounted on a ship propeller shaft and an ambient temperature of the ship propeller shaft;
constructing a first equation of the thrust of the propeller shaft of the ship and the longitudinal strain of the propeller shaft according to the strain signal and the ambient temperature, deriving the first equation and dispersing according to time steps to obtain a second equation;
Completing state prediction based on a matrix equation and an observation equation to obtain the first The prior estimation corresponding to each time step is completed based on the prior estimationState estimation under each time step to obtain the firstRecursively estimating time to the estimated variables corresponding to the time stepsRepeating state prediction and state estimation to obtain a new estimated variable, and calculating based on the new estimated variable and the first equation to obtain the shafting thrust of the ship propeller shaft.
Wherein, the first equivalent specific steps of constructing the thrust of the propeller shaft of the ship and the longitudinal strain thereof according to the strain signal and the ambient temperature are as follows
And respectively reading the strain signals of different strain gauges, wherein the number of the strain gauges meets the following formula:
Wherein, Respectively strain gaugesThe strain that is generated is such that,Longitudinal strain generated for thrust of the propeller shaft of the ship,Is the strain caused by the bending moment,Is the coefficient of thermal expansion of the shaft system,As a result of the ambient initial temperature,Is ambient temperature;
readings of strain gauges respectively connected with different strain gauges The formula of (2) is:
thrust of propeller shaft of ship And longitudinal strainThe relationship satisfies the following first equation:
Wherein, And (3) withThe elastic modulus and the sectional area of the shaft section at the mounting position of the strain gauge are respectively.
The first equation is derived and discrete according to time steps to obtain a second equation, and the specific equation is as follows:
Wherein, Is the firstThe strain gauge readings at the individual time steps,Is the firstThe strain gauge readings at the individual time steps,Is the firstThe thrust variation value at each time step,Is the firstAmbient temperature change values at various time steps.
Wherein the matrix equation based on the second equation is specifically expressed as
Order theThen the matrix equation is
Wherein, In the form of a state transition matrix,Model errors that are simulated noise;
The observation equation based on the second equivalent expression is specifically
Wherein, For the measured strain and the measured temperature change,In order to observe the equation,To measure noise.
Wherein, at the firstObtaining the first time stepThe prior estimates corresponding to the time steps are specifically:
Wherein, Is thatIn the first placeAn a priori estimate of the time step,Is thatIn the first placeA posterior estimate of the time step is obtained,Is thatIs a matrix of the estimated error covariance of (c),Is thatIs a matrix of the estimated error covariance of (c),For model errorsIs a covariance matrix of (a);
In the first place Obtaining the first time stepThe estimated variables corresponding to the time steps are specifically:
Wherein, In the form of a gain matrix,For measuring a sequence of deviations of the signal from the a priori estimate,To measure noiseIs a covariance matrix of (a);
covariance matrix And covariance matrixThe formulas of (a) are respectively as follows:
。
It is further preferred that the method further comprises the steps of, before acquiring the strain signal of at least 2 strain gauges mounted on the propeller shaft of the vessel and the ambient temperature of the propeller shaft of the vessel
Selecting a measuring point position on a ship propeller shaft, and measuring the diameter of a shaft section at the measuring point to obtain a sectional area;
Arranging a mounting ring at the measuring point to paste 2 strain gauges and checking the sensitivity coefficient of the strain gauges;
And connecting the two strain gauges in a half-bridge connection mode.
A high-precision real-time identification device for the thrust of a ship propeller shaft is provided with the high-precision real-time identification method for the thrust of the ship propeller shaft,
The device comprises a mounting component and a test piece, wherein the mounting component is mounted at a test point on a propeller shaft of a ship;
The mounting assembly comprises a first mounting piece and a second mounting piece;
The first mounting piece and the second mounting piece have the same structure and comprise a first arc-shaped piece, a second arc-shaped piece and at least one connecting rod;
The first arc-shaped piece and the second arc-shaped piece are semicircular, and two ends of the connecting rod are respectively connected with one side of the first arc-shaped piece and one side of the second arc-shaped piece, and the first arc-shaped piece and the second arc-shaped piece are symmetrically arranged;
The two ends of the first arc-shaped piece and the second arc-shaped piece are provided with connecting holes, the setting direction of the connecting holes is mutually perpendicular to the connecting rod, and the first mounting piece and the second mounting piece are matched with bolts and nuts through the connecting holes to realize bolt connection.
Specifically, the first mounting piece and the second mounting piece are both provided with two connecting rods;
And two ends of the two connecting rods are respectively connected with one side of the first arc-shaped piece and one side of the second arc-shaped piece, the connecting positions of the connecting rods divide the first arc-shaped piece or the second arc-shaped piece into three sections of arcs, and at least one test piece is arranged on each connecting rod.
The test piece is a strain gauge, and the two strain gauges which are oppositely arranged are electrically connected, and a half-bridge wire is adopted.
By adopting the technical scheme, the invention has the following advantages and positive effects compared with the prior art:
On one hand, the invention adopts the estimated-corrected weighted recursive least square estimation to identify the propeller thrust from the strain signal with noise interference, has stronger anti-interference capability, and can still maintain higher measurement precision in the strong interference noise environment. On the other hand, a functional relation between the ambient temperature and the thermal deformation is established in the recurrence equation, so that the thermal deformation error caused by the temperature can be compensated in the variable recurrence process. Finally, the strain gauge is attached to the mounting assembly, and the sensitivity coefficient of the attached strain gauge can be marked and checked in a laboratory, so that the influence of external factors such as the attaching mode of the strain gauge, the type of glue and the like is eliminated. The two strain gauges adopt half-bridge connection wires, so that the bending deformation influence of the rotating shaft can be eliminated, and the strain gauges directly transmit data to a computer for subsequent processing in a slip ring or wireless transmission mode.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.
FIG. 1 is a block diagram of a mounting assembly of the present invention;
FIG. 2 is a block diagram of another embodiment of a mounting assembly of the present invention;
FIG. 3 is a block diagram of a high-precision real-time identification device for thrust of a propeller shaft of a ship according to the present invention;
FIG. 4 is a schematic diagram of a strain gage half-bridge wire of the present invention;
FIG. 5 shows a method for high-precision real-time identification of thrust of a propeller shaft of a ship according to the present invention;
FIG. 6 is a graph showing the comparison of strain and thrust recognition effects of the present invention.
Description of the reference numerals
1, A ship propeller shaft, 2, an installation component, 3, a connecting hole and 4, a strain gauge.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will explain the specific embodiments of the present invention with reference to the accompanying drawings. It is evident that the drawings in the following description are only examples of the invention, from which other drawings and other embodiments can be obtained by a person skilled in the art without inventive effort.
For the sake of simplicity of the drawing, the parts relevant to the present invention are shown only schematically in the figures, which do not represent the actual structure thereof as a product. Additionally, in order to simplify the drawing for ease of understanding, components having the same structure or function in some of the drawings are shown schematically with only one of them, or only one of them is labeled. Herein, "a" means not only "only this one" but also "more than one" case.
The invention provides a high-precision real-time identification method and device for the thrust of a ship propeller shaft 1, which are further described in detail below with reference to the accompanying drawings and specific embodiments. Advantages and features of the invention will become more apparent from the following description and from the claims.
Referring to fig. 5, the present embodiment provides a high-precision real-time identification method for the thrust of a ship propeller shaft 1.
Before implementing the present embodiment, a measuring point position is selected on the propeller shaft 1 of the ship, the measuring point position is usually selected at the position of the propeller shaft 1 of the ship close to the propeller, and the diameter of the shaft section at the measuring point is measured to obtain the sectional area。
And a mounting ring is arranged at the measuring point position according to the diameter of the shaft section of the ship propeller shaft 1, as shown in figures 1 and 2. Referring to fig. 2 to 4, at least 2 strain gages 4 are adhered to the mounting ring, and the 2 strain gages 4 are respectively mounted on both sides of the mounting ring, i.e., oppositely disposed. After the completion of the installation, the sensitivity coefficient of the strain gauge 4 was checked in the laboratory (the mounting ring was not yet installed on the ship propeller shaft 1 at the time of the check). The mounting ring is secured to the shaft with a bolt-and-nut, as shown in fig. 3. The two strain gauges 4 on the mounting ring are connected in a half-bridge connection mode, so that the bending deformation influence caused by bending of the rotating shaft is eliminated, and the preparation stage is finished.
Referring to fig. 5, in the present embodiment, first, it is necessary to acquire a strain signal of at least 2 strain gauges 4 mounted on the propeller shaft 1 of the ship, and an ambient temperature of the propeller shaft 1 of the ship. Then a first equation of the thrust of the propeller shaft 1 of the ship and its longitudinal strain is constructed based on the strain signal and the ambient temperature.
When the propeller shaft 1 of the ship is subjected to the thrust of the propeller and the bending moment, the degrees of the two different strain gauges 4 are:
Wherein, Respectively strain gage 4The strain that is generated is such that,Longitudinal strain generated for thrust of the propeller shaft 1 of the ship,Is the strain caused by the bending moment,Is the coefficient of thermal expansion of the shaft system,As a result of the ambient initial temperature,Is ambient temperature.
The strain gauges are respectively electrically connected with different strain gauges 4, and the readings thereofIs satisfied with:
。
thereby obtaining the thrust of the propeller shaft 1 of the ship And longitudinal strainThe relationship between them satisfies the following first equation:
Wherein, And (3) withThe elastic modulus and the sectional area of the shaft section of the strain gauge 4 are respectively shown.
Then, deriving the first equation and discrete according to time steps to obtain a second equation, wherein the specific equation is as follows:
Wherein, Is the firstThe strain gauge readings at the individual time steps,Is the firstThe strain gauge readings at the individual time steps,Is the firstThe thrust variation value at each time step,Is the firstAmbient temperature change values at various time steps.
Further, the second equation is expressed as a matrix equation and an observation equation.
Order theThen it can be expressed as the following matrix equation:
Wherein, In the form of a state transition matrix,The modeling error is reflected to simulate the model error of noise, and the effect of the modeling error on the result is reflected.
The observation equation can be expressed as
Wherein, For the measured strain and the measured temperature change,In order to observe the equation,To measure noise, the effect of measurement errors on the result is reflected.
The two equations respectively form a matrix equation and an observation equation of the estimation-correction weighted recursive least square estimation. The recursive calculation process is as follows:
In the first place A time step, completing one-step prediction of the state to obtain the first stepThe prior estimation corresponding to each time step comprises the following specific formulas:
Wherein, Is thatIn the first placeAn a priori estimate of the time step,Is thatIn the first placeA posterior estimate of the time step is obtained,Is thatIs a matrix of the estimated error covariance of (c),Is thatIs a matrix of the estimated error covariance of (c),For model errorsIs a covariance matrix of (a).
Next, at the firstTime-step, using a priori estimatesThe specific formula of the completion state estimation is as follows:
Wherein, In the form of a gain matrix,For measuring a sequence of deviations of the signal from the a priori estimate,To measure noiseIs a covariance matrix of (a).
Recursively time toAnd repeating the state prediction and the state estimation to obtain a new estimated variable, and calculating based on the new estimated variable and the first equation to obtain the shafting thrust of the ship propeller shaft 1. In recursive computation, the covariance matrix caused by modeling errors and the covariance matrix caused by measurement noise need to be estimated. However, in practical applications, these two matrices are not easily determined and need to be adjusted according to the shafting and the field environment. The present embodiment provides a determinable covariance matrixAnd covariance matrixSpecifically, the formula of (2) is:
。
FIG. 6 shows the effect of the method on strain and thrust identification at a signal-to-noise ratio (SNR) as low as 20dB, with a maximum relative error of only 4.8%
Referring to fig. 1 to 4, the present embodiment provides a ship propeller shaft thrust high-precision real-time identification apparatus configured with the ship propeller shaft thrust high-precision real-time identification method of embodiment 1. Which comprises a mounting assembly 2 and a test piece. The installation component 2 is used for installing in the test point department on the ship propeller shaft 1, and the test piece is then pasted and is located on the installation component 2.
Referring to fig. 1 and 2, in the present embodiment, specifically, the mounting assembly 2 is described as being separable into a first mounting member and a second mounting member. The first mounting piece and the second mounting piece are identical in structure and comprise a first arc-shaped piece, a second arc-shaped piece and at least one connecting rod. The first arc-shaped piece and the second arc-shaped piece are of semicircular structures, and two ends of the connecting rod are connected with one side of the first arc-shaped piece and one side of the second arc-shaped piece respectively. When there is only one connecting rod, the connecting rod both ends respectively with the centre of first arc spare and the intermediate junction of second arc spare, when there are two connecting rods, the connecting rod both ends divide equally into the syllogic with first arc spare and second arc spare respectively, the tie point is the segmentation department of syllogic. The first arc-shaped piece and the second arc-shaped piece are symmetrically arranged, and the opening orientations are completely the same, namely the second arc-shaped piece can be obtained after the first arc-shaped piece translates.
At least one test piece is arranged in the center of the connecting rod, only one or a plurality of test pieces can be arranged, and the influence of random errors can be eliminated by using a plurality of strain gauges 4. Similarly, when the connecting rods are arranged in one piece, one or more test pieces are correspondingly arranged on the connecting rods, and when the connecting rods are arranged in a plurality of pieces, one or more test pieces are correspondingly arranged on each connecting rod.
The both ends of first arc spare and second arc spare all are equipped with connecting hole 3, and the direction and the connecting rod mutually perpendicular of seting up of connecting hole 3. The first arc-shaped piece of the first installation piece and the first arc-shaped piece of the second installation piece pass through the connecting holes 3 of the first arc-shaped piece and the second arc-shaped piece through bolts and nuts, so that the bolt connection is realized, and the second arc-shaped pieces are the same. So that the first and second mounting members are interconnected to form an annular mounting assembly 2 which is snugly arranged around the propeller shaft 1 of the vessel, as shown in fig. 3.
In addition, referring to fig. 4, the test piece is a strain gauge 4, and two strain gauges 4 disposed opposite to each other are electrically connected, and a half bridge wire is used to eliminate the bending deformation effect of the rotating shaft.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, it is within the scope of the appended claims and their equivalents to fall within the scope of the invention.
Claims (7)
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| CN202211390047.4A CN115636063B (en) | 2022-11-08 | 2022-11-08 | A method and device for high-precision real-time identification of ship propeller shaft thrust |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017089644A1 (en) * | 2015-11-26 | 2017-06-01 | Wärtsilä Finland Oy | Marine vessel performance monitoring |
| KR20220001280A (en) * | 2020-06-29 | 2022-01-05 | 한국해양대학교 산학협력단 | System and method for prediction diagnosis of ship propeller and shaft condition using digital twin |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017089644A1 (en) * | 2015-11-26 | 2017-06-01 | Wärtsilä Finland Oy | Marine vessel performance monitoring |
| KR20220001280A (en) * | 2020-06-29 | 2022-01-05 | 한국해양대학교 산학협력단 | System and method for prediction diagnosis of ship propeller and shaft condition using digital twin |
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