A carrier bearing angle calculation method and system

Abstract

The application provides a carrier track angle calculation method and system, which comprises the following steps: calculating a carrier sailing track equation, converting the carrier sailing track equation into a spatial orthogonal parameter equation, and obtaining track data of different orthogonal directions with time as a parameter; setting a time window for the track data of each direction, and predicting track data in a future certain time by using a mirror image extension method; performing EMD decomposition on the track data of each direction in the time window and the mirror image extension interval, and obtaining an average trend component; and calculating a carrier track angle according to the average trend component. The EMD decomposition of the carrier motion track can inhibit the interference of high-frequency disturbance on the carrier, significantly reduce the additional energy consumption caused by frequent control, and improve the control quality of the system.

Description

Technical Field

[0001] This invention belongs to the field of track angle algorithm technology, specifically relating to a method and system for calculating the track angle of a carrier. Background Technology

[0002] Track angle is a crucial parameter for the motion control of underwater vehicles such as surface ships and underwater vehicles. However, during actual navigation, the track angle formed by the vehicle's actual trajectory is not equal to the heading angle due to the influence of ocean currents. Furthermore, the vehicle is affected by waves and wind, causing periodic reciprocating motions in control parameters such as attitude, speed, and position. While these motions are real, they constitute high-frequency disturbances to the control system. A complete response to these disturbances would reduce the vehicle's range, and the randomness of these disturbances is also detrimental to the vehicle's control stability. Therefore, filtering out these disturbances and accurately extracting the vehicle's actual track curve from the inertial navigation system's motion trajectory is essential for improving the operational efficiency of underwater vehicles.

[0003] EMD (Empirical Mode Decomposition) is a novel method for processing non-stationary signals. It does not require any pre-defined basis functions and better reflects the physical meaning of the signal compared to other time-frequency analysis methods. It is suitable for analyzing both linear and stationary signals as well as nonlinear and non-stationary signals.

[0004] EMD decomposition of the carrier's motion trajectory containing high-frequency disturbances and noise can extract the actual controlled motion trajectory trend component of the carrier. The track angle calculated from this can truly reflect the carrier's motion direction. Using this as a control parameter, compared with the original heading angle or the original track angle without extraction, can suppress the interference of high-frequency disturbances on the carrier, significantly reduce the additional energy consumption caused by frequent control, and improve the system control quality. Summary of the Invention

[0005] To address the technical issues of high-frequency disturbances and noise in the actual flight trajectory of a carrier, this invention provides a method and system for calculating the carrier track angle. The method performs EMD decomposition on the carrier's motion trajectory, extracts the trend component of the carrier's actual controlled motion trajectory, and calculates the track angle to accurately reflect the carrier's motion direction.

[0006] To address the aforementioned technical problems, this invention provides a method for calculating the trajectory angle of a carrier, comprising the following steps:

[0007] The statistical carrier trajectory equations are converted into spatially orthogonal parametric equations to obtain trajectories in different orthogonal directions with time as the parameter.

[0008] A time window is set for the trajectory in each direction, and the mirror expansion method is used to predict the trajectory data within a certain period of time in the future;

[0009] Within the time window and the mirror extension interval, EMD decomposition is performed on the trajectory in each direction to obtain the average trend component;

[0010] The carrier's trajectory angle is calculated based on the average trend component.

[0011] Furthermore, the mirror expansion method involves performing a central mirror expansion centered on the current position; the mirror expansion interval is smaller than the time window.

[0012] Furthermore, the time window is set the same for the trajectory in each direction.

[0013] Furthermore, the EMD decomposition includes the following steps:

[0014] Calculate the local maxima and local minima of the trajectory;

[0015] Calculate the upper and lower envelope curves based on the local maxima and local minima of the trajectory, respectively;

[0016] Calculate the mean values ​​of the upper and lower envelope curves of the trajectory;

[0017] Calculate the intrinsic mode function of the trajectory;

[0018] Determine whether the intrinsic mode function satisfies the intrinsic mode function condition. If it does, denote the intrinsic mode function as the intrinsic mode and calculate the difference between the trajectory and the intrinsic mode as the trajectory component, and start iterative calculation. Otherwise, use the difference between the trajectory and the intrinsic mode function as the trajectory component and start iterative calculation until the intrinsic mode function condition is satisfied.

[0019] The calculation is repeated iteratively until the average trend component of the trajectory is obtained.

[0020] Furthermore, the method for calculating the local maxima and minima of the trajectory specifically includes the following steps.

[0021] S101, Calculate x i (t) Differential output Δx at each time step i (t j )=x i (t j+1 )-x i (t j ), x i (t) represents the i-th component value of the trajectory at time t, t j and t j+1 Indicates two consecutive moments;

[0022] S102, if Δx i (t j ) = 0 or sign(Δx) i (tj ))≠sign(Δx i (t j+1 Then x i (t j () represents the extreme point, and sign() is the sign function;

[0023] S103. Maximum and minimum points alternate, distinguishing all local maxima and minima. Further, the intrinsic mode function is...

[0024] h i (t)=x i (t)-m i (t)

[0025] Where, x i (t) represents the i-th component value of the trajectory at time t, m i (t) represents the mean of the upper and lower envelope curves;

[0026] The intrinsic mode function conditions include

[0027] Within the calculation interval, the sum of the number of local maxima and local minima of the intrinsic mode function must be equal to or at most differ by one from the number of zero crossings;

[0028] Integrating the intrinsic mode function, the integral value is less than the threshold value.

[0029] Furthermore, the threshold value is less than 5% of the local maxima of the intrinsic mode function.

[0030] Furthermore, the calculated vehicle trajectory angle is...

[0031]

[0032] Where x(t) i ), y(t) i ) represent the eastward trajectory and the northward trajectory, respectively, t i and t i-1 ΔS represents two consecutive moments. N ΔS represents the northward displacement at consecutive moments. E The displacement is eastward at adjacent moments.

[0033] Furthermore, the carrier track angle calculation method is used for extracting the track angle of surface ships or underwater vehicles.

[0034] This invention also provides a carrier track angle calculation system, including...

[0035] The vehicle trajectory acquisition module is used to statistically analyze the vehicle's flight trajectory equations, convert them into spatially orthogonal parametric equations, and obtain trajectories in different orthogonal directions with time as a parameter.

[0036] The windowing module is used to divide trajectories in different directions according to time windows;

[0037] The mirror extension module is used to predict trajectory data within a certain future time frame using the mirror extension method.

[0038] The EMD module is used to perform EMD decomposition on the trajectory to obtain the average trend component.

[0039] The track angle output module is used to calculate the carrier track angle based on the average trend component.

[0040] The beneficial effects of this invention compared to the prior art are as follows:

[0041] The carrier trajectory angle calculation method based on EMD decomposition provided by this invention decomposes the carrier motion trajectory into EMD and extracts the actual controlled motion trajectory trend component of the carrier. This method can suppress the interference of high-frequency disturbances on the carrier, significantly reduce the additional energy consumption caused by frequent control, and improve the system control quality. At the same time, it predicts trajectory data by mirror expansion, reduces the instability of edge data, ensures the real-time performance of the calculation, and obtains real-time results.

[0042] The carrier track angle extraction method provided by this invention is mainly used to eliminate high-frequency fluctuations in track angle caused by external interference when waterborne carriers such as surface ships and underwater vehicles are navigating, and to provide more suitable control input parameters for the carrier control system. Attached Figure Description

[0043] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0044] Figure 1 A schematic diagram of the mirror extension provided for a specific embodiment of the present invention;

[0045] Figure 2 A schematic diagram of the intrinsic mode function curve that meets the requirements, provided for a specific embodiment of the present invention;

[0046] Figure 3 The trajectory curve after EMD decomposition and smoothing is provided for a specific embodiment of the present invention. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] This invention provides a method for calculating the carrier track angle based on EMD decomposition, comprising the following steps:

[0050] The statistical carrier trajectory equations are converted into spatially orthogonal parametric equations to obtain trajectories in different orthogonal directions with time as the parameter.

[0051] A time window is set for the trajectory in each direction, and the mirror expansion method is used to predict the trajectory data within a certain period of time in the future;

[0052] Within the time window and the mirror extension interval, EMD decomposition is performed on the trajectory in each direction to obtain the average trend component;

[0053] The carrier's trajectory angle is calculated based on the average trend component.

[0054] The present invention provides a carrier track angle calculation method that extracts the actual controlled motion trajectory trend component of the carrier by performing EMD decomposition on the carrier's motion trajectory. This method can suppress the interference of high-frequency disturbances on the carrier, significantly reduce the additional energy consumption caused by frequent control, and improve the system control quality. At the same time, it reduces the instability of edge data by predicting track data through mirror expansion, ensuring the real-time nature of the calculation and obtaining real-time results.

[0055] Preferably, the time window is set consistently for each directional trajectory to simplify calculations.

[0056] Preferably, the mirror expansion method involves performing a central mirror expansion centered on the current position to predict the trajectory over a future period. Preferably, since the target's heading will not change drastically in a short time, setting the mirror expansion interval to be smaller than the time window ensures the accuracy of the calculation.

[0057] Furthermore, the EMD decomposition includes the following steps:

[0058] Calculate the local maxima and minima of the trajectory;

[0059] Calculate the upper and lower envelope curves based on the local maxima and minima of the trajectory;

[0060] Calculate the mean values ​​of the upper and lower envelope curves of the trajectory;

[0061] Calculate the intrinsic mode function of the trajectory;

[0062] Determine whether the intrinsic mode function satisfies the intrinsic mode function condition. If it does, denote the intrinsic mode function as the intrinsic mode and calculate the difference between the trajectory and the intrinsic mode as the trajectory component, and start iterative calculation. Otherwise, use the difference between the trajectory and the intrinsic mode function as the trajectory component and start iterative calculation until the intrinsic mode function condition is satisfied.

[0063] The calculation is repeated iteratively until the average trend component of the trajectory is obtained.

[0064] The carrier track angle calculation method based on EMD decomposition provided by this invention is applicable to the extraction of track angles of waterborne carriers such as surface ships and underwater vehicles.

[0065] This invention also provides a carrier track angle calculation system based on EMD decomposition, including...

[0066] The vehicle trajectory acquisition module is used to statistically analyze the vehicle's flight trajectory equations, convert them into spatially orthogonal parametric equations, and obtain trajectories in different orthogonal directions with time as a parameter.

[0067] The windowing module is used to divide trajectories in different directions according to time windows;

[0068] The mirror extension module is used to predict trajectory data within a certain future time frame using the mirror extension method.

[0069] The EMD module is used to perform EMD decomposition on the trajectory to obtain the average trend component.

[0070] The track angle output module is used to calculate the carrier track angle based on the average trend component.

[0071] The technical solution of the present invention will be described in detail below, taking the carrier's surface navigation as an example.

[0072] S1. When the carrier is sailing on the water, its trajectory can be described by the two-dimensional plane equation D(x,y,t)=0, where x represents the eastward displacement, y represents the northward displacement, and t is time.

[0073] S2, the trajectory D(x,y,t)=0 can be represented as a spatially orthogonal parametric equation, obtaining trajectories x(t) and y(t) in different orthogonal directions with time as the parameter.

[0074] S3. Perform EMD decomposition on x(t) and y(t) respectively, where t∈[0,t] k For example, x(t):

[0075] S31. Apply a window to the data x(t) (i.e., set a time window) to determine the time period [t]. k-T ,t k ], t kIt is the current moment, T is the width of the time window, and t t-T The moment before a time window;

[0076] S32, Let x i (t)=x(t),i=0, start iterative calculation.

[0077] i represents the i-th iteration, x i (t) represents the i-th component value of the trajectory at time t.

[0078] S33. During real-time calculations, considering that the target course of the waterborne vehicle will not change drastically for most of the time, a mirror-expansion method can be used to predict data for future moments to reduce instability in edge data. For example... Figure 1 As shown, data for future moments is predicted through a central mirror expansion method.

[0079] Specifically, using t k The calculation method is as follows: A central mirror expansion is performed with time x(t) as the center.

[0080] x(t k+n )=2x(t k )-x(t k-n ),n≤M (1)

[0081] Where [t] k-M ,t k+M [] represents the mirror region. The mirror extension interval M < T, where n represents the sampling point.

[0082] S34. In the time window and mirror extension interval [t] k-T ,t k+M Within ], calculate x i (t) Local maxima and minima during the iteration process, the specific process is as follows:

[0083] S101, Calculate x i (t) Differential output Δx at each time step i (t j )=x i (t j+1 )-x i (t j ), where t j ∈[t k-T ,t k+M ], x i (t) represents the i-th component value of the trajectory at time t, t j and t j+1 Indicates two consecutive moments;

[0084] S102, if Δx i (tj ) = 0 or sign(Δx) i (t j ))≠sign(Δx i (t j+1 Then x i (t j () represents the extreme point, and sign() is the sign function;

[0085] S103. Since maxima and minima alternate, we first determine the type of the first maxima. If it is a maxima, then the maxima in odd-numbered positions are maxima and the maxima in even-numbered positions are minima. Conversely, the maxima in odd-numbered positions are minima and the maxima in even-numbered positions are maxima.

[0086] S34. Calculate the envelope, and use the piecewise cubic curve fitting method to obtain the upper envelope curve and the lower envelope curve;

[0087] S35. Calculate the upper envelope curve E. ui (t) and the lower envelope curve E li The mean m of (t) i (t)=(E ui (t)+E li (t)) / 2

[0088] S36. Calculate the intrinsic mode function h i (t)=x i (t)-m i (t)

[0089] S37, Determine h i Does (t) satisfy the intrinsic mode function condition, i.e.:

[0090] (1) In [t k-T ,t k+M Within the range, h i (t) The sum of the number of local maxima and local minima must be equal to or at most differ by one from the number of zeros;

[0091] (2) For h i (t) Perform integration, and use a threshold value as the judgment condition. Preferably, the threshold value is set to be less than 5% of the local maxima of the intrinsic mode function. The intrinsic mode function curve that meets the requirements is as follows: Figure 2 As shown.

[0092] S38, if h i If (t) satisfies the intrinsic mode function condition, then h i (t) is called the i-th intrinsic mode, let x i+1 (t)=x i (t)-h i(t), calculated iteratively starting from step S34; e.g., h i If (t) does not satisfy the inherent mode function condition, then proceed to step S39.

[0093] S39, Let x ij (t)=x i (t)-h i (t), repeat steps S34 to S38 until h ij (t)=x ij (t)-m ij (t) satisfies the intrinsic mode function condition, let x i+1 (t)=x i (t)-h ij (t), the calculation is performed iteratively starting from step S34;

[0094] S40. After p iterations, x(t) can be expressed in the following form.

[0095]

[0096] Where r(t) is called the average trend component, the iterative calculation ends when r(t) is a constant or a monotonic function, and p is the number of iterations.

[0097] r(t) represents the non-oscillatory component of x(t). When x(t) is the trajectory curve of the carrier motion, r(t) represents the stable trajectory curve after eliminating high-frequency interference. Generally, removing the first or second order IMF (Intrinsic Mode Function) components yields a relatively ideal stable trajectory curve, such as... Figure 3 As shown.

[0098] 4. Calculate the trajectory angle of r(t).

[0099]

[0100] Among them, t i and t i-1 ΔS represents two consecutive moments. N ΔS represents the northward displacement at consecutive moments. E The displacement is eastward at adjacent moments.

[0101] For example, track angle Figure 3 As shown in the figure, the track angle fluctuation obtained after EMD decomposition is significantly reduced.

[0102] This invention designs a carrier trajectory angle extraction method, which performs EMD decomposition on the carrier's motion trajectory to extract the actual controlled motion trajectory trend component of the carrier. This method can suppress the interference of high-frequency disturbances on the carrier, significantly reduce the additional energy consumption caused by frequent control, and improve the system control quality. At the same time, it predicts trajectory data by mirror expansion, reduces the instability of edge data, ensures the real-time performance of the calculation, and obtains real-time results.

[0103] The features described and / or illustrated above with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, and / or in combination with or in lieu of features in other embodiments.

[0104] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, components, or combinations thereof.

[0105] Many features and advantages of these embodiments are apparent from this detailed description, and therefore the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the invention are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0107] The parts of this invention not described in detail are techniques known to those skilled in the art.

Claims

1. A method for calculating the trajectory angle of a carrier, characterized in that, Includes the following steps The statistical carrier trajectory equations are converted into spatially orthogonal parametric equations to obtain trajectories in different orthogonal directions with time as the parameter. A time window is set for the trajectory in each direction, and the mirror expansion method is used to predict the trajectory data within a certain period of time in the future; Within the time window and the mirror extension interval, EMD decomposition is performed on the trajectory in each direction to obtain the average trend component; Calculate the carrier's trajectory angle based on the average trend component; The EMD decomposition includes the following steps: Calculate the local maxima and local minima of the trajectory; Calculate the upper and lower envelope curves based on the local maxima and local minima of the trajectory, respectively; Calculate the mean values ​​of the upper and lower envelope curves of the trajectory; Calculate the intrinsic mode function of the trajectory; Determine whether the intrinsic mode function satisfies the intrinsic mode function condition. If it does, denote the intrinsic mode function as the intrinsic mode and calculate the difference between the trajectory and the intrinsic mode as the trajectory component, and start iterative calculation. Otherwise, use the difference between the trajectory and the intrinsic mode function as the trajectory component and start iterative calculation until the intrinsic mode function condition is satisfied. The calculation is repeated iteratively until the average trend component of the trajectory is obtained.

2. The method for calculating the carrier track angle according to claim 1, characterized in that, The mirror expansion method involves performing a central mirror expansion with the current position as the center; the mirror expansion interval is smaller than the time window.

3. The method for calculating the carrier track angle according to claim 1, characterized in that, The time window is set the same for the trajectory in each direction.

4. The method for calculating the carrier track angle according to claim 1, characterized in that, The method for calculating the local maxima and minima of the trajectory specifically includes the following steps. S101, Calculation Differential output at each time step , Representing the trajectory Time of the first Each component value and Indicates two consecutive moments; S102, if or ,but It is an extreme point. It is a symbolic function; S103. Maximum and minimum points appear alternately, distinguishing all local maxima and minima.

5. The method for calculating the carrier track angle according to claim 1, characterized in that, The intrinsic mode function is: ,in, Representing the trajectory Time of the first Each component value This represents the mean of the upper and lower envelope curves; The intrinsic mode function conditions include Within the calculation interval, the sum of the number of local maxima and local minima of the intrinsic mode function must be equal to or at most differ by one from the number of zero crossings; Integrating the intrinsic mode function, the integral value is less than the threshold value.

6. The method for calculating the carrier track angle according to claim 5, characterized in that, The threshold value is less than 5% of the local maxima of the intrinsic mode function.

7. The method for calculating the carrier track angle according to claim 5, characterized in that, The calculation vehicle's trajectory angle is ,in, , These are the eastward trajectory and the northward trajectory, respectively. and This indicates two consecutive moments. The displacement is northward at adjacent moments. The displacement is eastward at adjacent moments.

8. The method for calculating the carrier track angle according to any one of claims 1 to 7, characterized in that, The method for calculating the trajectory angle of a carrier is used to extract the trajectory angle of surface ships or underwater vehicles.

9. A carrier trajectory angle calculation system, characterized in that, The system comprising the method according to any one of claims 1 to 8 The vehicle trajectory acquisition module is used to statistically analyze the vehicle's flight trajectory equations, convert them into spatially orthogonal parametric equations, and obtain trajectories in different orthogonal directions with time as a parameter. The windowing module is used to divide trajectories in different directions according to time windows; The mirror extension module is used to predict trajectory data within a certain future time frame using the mirror extension method. The EMD module is used to perform EMD decomposition on the trajectory to obtain the average trend component. The track angle output module is used to calculate the carrier track angle based on the average trend component.

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