Standing wave distance measurement method, object edge identification method and device

Abstract

The invention discloses a standing wave ranging method and an object edge identification method and device, and the method comprises the steps: obtaining a signal wave reflected by a to-be-ranged object and a standing wave signal formed by the transmitted signal wave after a sound wave sensor transmits the signal wave to the to-be-ranged object; obtaining a standing wave signal expression at an original point where a microphone of the sonic sensor is located, and performing power transformation; expanding the standing wave signal expression after power transformation in a frequency domain to obtain an unbiased differential function expression; and performing coefficient scaling on the unbiased differential function expression at the frequency where the pulse peak is formed to obtain a distance frequency spectrum, wherein the peak value of the distance frequency spectrum is the distance from the sonic sensor to the object to be subjected to distance measurement. The acoustic method is used to realize shape measurement and identification of objects with blind spots in vision measurement, such as mirror surface objects or transparent earth surface objects, and the defects of vision measurement of the unmanned aerial vehicle are made up, so that the unmanned aerial vehicle has better robustness in measurement of the earth object.

Description

Technical Field

[0001] This invention relates to the field of distance measurement, specifically to a standing wave ranging method, an object edge recognition method, and an apparatus. Background Technology

[0002] Power transmission inevitably traverses areas with complex geological conditions, variable climates, and harsh environments, such as high mountains and plateaus. Transmission towers, as the connection points between high-voltage transmission lines and the ground, are often built on steep mountain slopes far from cities, increasing the likelihood of landslides. Therefore, utilizing drones for transmission line maintenance is of great significance.

[0003] In some applications where drone operations require close tracking of ground features, such as geological exploration, agricultural operations, and environmental monitoring, it is necessary to identify objects on the ground. Currently widely used optical photography methods are subject to light interference, and there are blind spots in visual measurement for objects such as mirrors or transparent surfaces. Summary of the Invention

[0004] The purpose of this invention is to provide a method for detecting mirrored or transparent ground objects using standing waves, thereby solving the technical problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a standing wave ranging method, comprising:

[0006] The standing wave signal formed by the signal wave reflected by the object to be measured and the transmitted signal wave after the acoustic wave sensor transmits a signal wave to the object to be measured is obtained.

[0007] Obtain the expression for the standing wave signal at the origin where the microphone of the acoustic wave sensor is located and perform a power transform;

[0008] The expression for the standing wave signal after power transformation is expanded in the frequency domain to obtain the expression for the unbiased differential function.

[0009] The distance spectrum is obtained by scaling the unbiased differential function expression at the frequency where the pulse peak is formed. The peak value of the distance spectrum is the distance from the acoustic sensor to the object to be measured.

[0010] As a further aspect of the present invention, obtaining the standing wave signal expression at the origin of the microphone of the acoustic wave sensor and performing a power transformation includes:

[0011] The signal transmitted by the acoustic sensor to point x at time t is denoted as v. Tr (t,x),

[0012] Where f(τ) is the instantaneous frequency, defined as:

[0013] A, c, θ represent sound amplitude, sound velocity, and phase, respectively; T represents duration; f1 represents the lowest frequency; f N f represents the highest frequency. w Indicates bandwidth f w =f N -f1,

[0014] The signal reflected by the stationary object at a distance L from the acoustic sensor is denoted as v. Ref (t,x),

[0015] The origin v of the microphone of the sound wave sensor C (t,0)=v Tr (t,0)+v R The standing wave signal at (t, 0) is denoted as v. C (t,0), v C (t,0)=v Tr (t,0)+v R (t,0), then v C The power of (t,0) becomes:

[0016]

[0017] As a further aspect of the present invention, the step of expanding the power-transformed standing wave signal expression in the frequency domain to obtain an unbiased differential function expression includes:

[0018] v C The power transformation of (t,0) is: Where C0 is the constant term of the interference.

[0019] On the other hand, the present invention provides an object edge recognition method, comprising:

[0020] The standing wave signal formed by the signal wave reflected by the object to be measured and the transmitted signal wave after the acoustic wave sensor transmits a signal wave to the object to be measured is obtained.

[0021] Model the transmitted and reflected signals in the frequency domain;

[0022] The power spectrum function is obtained based on the frequency domain model of the standing wave signal. The distance spectrum function is obtained by performing a Fourier transform on the power spectrum. Several peaks of the distance spectrum are the edge distances from the acoustic sensor to the object to be measured.

[0023] As a further aspect of the present invention, the modeling of the transmitted and reflected signals in the frequency domain includes:

[0024] The transmitted signal is modeled as a unit sound signal sinωt;

[0025] In a ring with radius r and width dr located at the origin x = 0, the reflected sound signal with angular frequency ω is denoted as v. Ref,r,ω (t,0)dr, assuming the gain coefficient and reflection phase shift remain constant across the entire frequency range, the reflected signal is modeled based on Lambert's law and the inverse distance law as follows:

[0026]

[0027] For v Ref,r,ω Integrating dr at (t,0) yields the reflected signal v. Ref,ω The formula for calculating (t) is as follows:

[0028]

[0029] in,

[0030] As a further embodiment of the present invention, the distance spectrum function is:

[0031] On the other hand, the present invention provides a standing wave ranging device, comprising:

[0032] The standing wave signal generation module acquires the standing wave signal formed by the signal wave reflected by the object to be measured after the acoustic wave sensor transmits the signal wave to the object to be measured and the transmitted signal wave.

[0033] The power transformation module obtains the expression of the standing wave signal at the origin where the microphone of the acoustic wave sensor is located and performs a power transformation.

[0034] The frequency domain expansion module expands the power-transformed standing wave signal expression in the frequency domain to obtain the unbiased differential function expression;

[0035] The distance spectrum calculation module scales the unbiased differential function expression at the frequency where the pulse peak is formed to obtain the distance spectrum. The peak value of the distance spectrum is the distance from the acoustic sensor to the object to be measured.

[0036] On the other hand, the present invention provides an object edge recognition device, comprising:

[0037] The standing wave signal generation module is used in which the acoustic wave sensor transmits a signal wave to the object to be measured, and the signal wave reflected by the object to be measured forms a standing wave signal with the transmitted signal wave.

[0038] The frequency domain modeling module models the transmitted and reflected signals in the frequency domain;

[0039] The distance spectrum calculation module obtains the power spectrum function based on the frequency domain model of the standing wave signal, and performs a Fourier transform on the power spectrum to obtain the distance spectrum function. Several peaks of the distance spectrum are the edge distances from the acoustic sensor to the object to be measured.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] This invention utilizes standing waves formed by transmitted and reflected acoustic signals to identify the size and shape of target objects. It employs acoustic methods to achieve shape measurement and identification of objects with blind spots in visual measurements, such as mirrored or transparent surfaces. This compensates for the shortcomings of UAV visual measurement, making UAV-based ground object measurements more robust. This invention concatenates the traditional distance-spectrum method based on Fast Fourier Transform to find a target region represented by a main peak, and then selects more refined query points around the main peak, thereby simultaneously obtaining high resolution and improving computational efficiency. Attached Figure Description

[0042] Figure 1 This is a schematic diagram illustrating the principle of the standing wave ranging method;

[0043] Figure 2 This is a flowchart of a standing wave ranging method in one embodiment;

[0044] Figure 3 This is a flowchart of an object edge recognition method in one embodiment;

[0045] Figure 4 This is a schematic diagram of a standing wave ranging device in one embodiment;

[0046] Figure 5 This is a schematic diagram of an object edge recognition device in one embodiment. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of one or more embodiments of this specification, and not all embodiments. Based on the embodiments in one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0048] It should be noted that, unless otherwise specified, one or more embodiments and features described in this specification can be combined with each other. One or more embodiments of this specification will now be described in detail with reference to the accompanying drawings and examples.

[0049] See Figure 1 The drone is equipped with a sound wave sensor that emits a signal wave to the object under test. The object under test reflects the signal wave back to the sound wave sensor, and the emitted wave and the emitted wave are superimposed to form a standing wave signal.

[0050] See Figure 2 This embodiment provides a standing wave ranging method, including:

[0051] S102, acquire the standing wave signal formed by the signal wave reflected by the object to be measured and the transmitted signal wave after the acoustic wave sensor transmits the signal wave to the object to be measured;

[0052] S104, obtain the standing wave signal expression at the origin where the microphone of the acoustic wave sensor is located and perform a power transformation;

[0053] S106, expand the power-transformed standing wave signal expression in the frequency domain to obtain the unbiased differential function expression;

[0054] S108, the unbiased differential function expression is scaled at the frequency where the pulse peak is formed to obtain the distance spectrum. The peak value of the distance spectrum is the distance from the acoustic sensor to the object to be measured.

[0055] Furthermore, the expression for the standing wave signal at the origin where the microphone of the acoustic wave sensor is located is obtained and a power transform is performed, including:

[0056] The signal transmitted by the acoustic sensor to point x at time t is denoted as v. Tr (t,x),

[0057] Where f(τ) is the instantaneous frequency, defined as:

[0058] A, c, θ represent sound amplitude, sound velocity, and phase, respectively; T represents duration; f1 represents the lowest frequency; f N f represents the highest frequency. w Indicates bandwidth f w =f N -f1,

[0059] The signal reflected by the stationary object at a distance L from the acoustic sensor is denoted as v. Ref (t,x),

[0060] The origin v of the microphone of the sound wave sensor C (t,0)=v Tr (t,0)+v R The standing wave signal at (t, 0) is denoted as v. C (t,0), v C (t,0)=vTr (t,0)+v R (t,0), then v C The power of (t,0) becomes:

[0061]

[0062] Furthermore, the power-transformed standing wave signal expression is expanded in the frequency domain to obtain the unbiased differential function expression, including:

[0063] v C The power transformation of (t,0) is: Where C0 is the constant term of the interference.

[0064] Since the above equation is a partial cosine function, in the frequency range (f1, f2)... N The power spectrum of the unbiased p(f,0) forms a pulse peak at the frequency of the cosine function. This peak is determined by coefficients... With rescaling, the power spectrum becomes a "distance spectrum" because it has a peak at L, representing the distance to the object.

[0065] See Figure 3 An object edge recognition method, comprising:

[0066] S302, after the acoustic wave sensor transmits a signal wave to the object to be measured, the standing wave signal formed by the signal wave reflected by the object to be measured and the transmitted signal wave;

[0067] S304 models the transmitted and reflected signals in the frequency domain;

[0068] S306. The power spectrum function is obtained based on the frequency domain model of the standing wave signal. The distance spectrum function is obtained by performing a Fourier transform on the power spectrum. Several peaks of the distance spectrum are the edge distances from the acoustic sensor to the object to be measured.

[0069] Furthermore, the transmitted and reflected signals are modeled in the frequency domain, including:

[0070] Assume a disk of radius R and distance L as the target object. For simplicity, the observation point is located on a straight line perpendicular to the center of the disk. The short-duration chirp signal can be approximated as a sine wave, and the phase of the transmitted signal does not affect the distance spectrum. The transmitted signal is modeled as a unit sound signal sinωt; the reflected sound signal with angular frequency ω in a ring of radius r and width dr at the origin x = 0 is denoted as v. Ref,r,ω (t,0)dr. Assuming the gain coefficient and reflection phase shift remain constant across the entire frequency range, the reflected signal is modeled based on Lambert's law and the inverse distance law as follows:

[0071]

[0072] For v Ref,r,ω Integrating dr at (t,0) yields the reflected signal v. Ref,ω The formula for calculating (t) is as follows:

[0073]

[0074] in,

[0075] The distance spectrum function is:

[0076] The power spectrum p(ω,0) can be approximated by a constant and two sinc functions with coefficients a and b. Considering that ω is given over a finite frequency range, the "power spectrum" of p(ω,0) of ω forms a distance spectrum with two peaks at a and b, corresponding to the two edges of the disk.

[0077] Since the range spectrum can be calculated using the Fourier transform of the power spectrum p(f,0), the Fast Fourier Transform (FFT) is an efficient computational method. Conventional range spectra based on FFT exhibit uniform resolution, and the highest resolution of the range spectrum is... This invention also proposes a method using Discrete Fourier Transform (DFT) to calculate the distance spectrum by using dense query points around the first peak. The query points can be arbitrarily selected using DFT, and the obtained distance spectrum can have higher resolution than that obtained using Fast Fourier Transform (FFT). However, since the DFT method requires more computation, this invention concatenates the traditional FFT-based distance spectrum to find a target region represented by a main peak, and then selects more refined query points around the main peak, thereby simultaneously obtaining high resolution and improving computational efficiency.

[0078] See Figure 4 Corresponding to the aforementioned embodiments of the standing wave ranging method, this application also provides a standing wave ranging device, which includes:

[0079] The standing wave signal generation module 401 acquires the standing wave signal formed by the signal wave reflected by the object to be measured and the transmitted signal wave after the acoustic wave sensor transmits the signal wave to the object to be measured.

[0080] The power transformation module 402 obtains the standing wave signal expression at the origin where the microphone of the acoustic wave sensor is located and performs a power transformation.

[0081] The frequency domain expansion module 403 expands the power-transformed standing wave signal expression in the frequency domain to obtain the unbiased differential function expression;

[0082] The distance spectrum calculation module 404 scales the unbiased differential function expression at the frequency where the pulse peak is formed to obtain the distance spectrum. The peak value of the distance spectrum is the distance from the acoustic sensor to the object to be measured.

[0083] It should be noted that the embodiments of the standing wave ranging device and the embodiments of the standing wave ranging method in this specification are based on the same inventive concept. Therefore, the specific implementation of this embodiment can be referred to the implementation of the corresponding standing wave ranging method mentioned above, and the repeated parts will not be described again.

[0084] See Figure 5 Corresponding to the embodiments of the aforementioned object edge recognition method, this application also provides an object edge recognition device, which includes:

[0085] Standing wave signal generation module 501: The acoustic wave sensor emits a signal wave to the object to be measured, and the signal wave reflected by the object to be measured forms a standing wave signal with the emitted signal wave.

[0086] Frequency domain modeling module 502 models the transmitted and reflected signals in the frequency domain;

[0087] The distance spectrum calculation module 503 obtains the power spectrum function based on the frequency domain model of the standing wave signal, and performs a Fourier transform on the power spectrum to obtain the distance spectrum function. Several peaks of the distance spectrum are the edge distances from the acoustic sensor to the object to be measured.

[0088] It should be noted that the embodiments of the object edge recognition device in this specification and the embodiments of the object edge recognition method in this specification are based on the same inventive concept. Therefore, the specific implementation of this embodiment can be referred to the implementation of the corresponding object edge recognition method mentioned above, and the repeated parts will not be described again.

[0089] The above description is merely an embodiment of one or more embodiments of this specification and is not intended to limit this specification. Various modifications and variations can be made to this specification by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this specification should be included within the scope of the claims of this specification.

Claims

1. A standing wave ranging method, characterized in that, include: The standing wave signal formed by the signal wave reflected by the object to be measured and the transmitted signal wave after the acoustic wave sensor transmits a signal wave to the object to be measured is obtained. Obtain the expression for the standing wave signal at the origin where the microphone of the acoustic wave sensor is located and perform a power transform; The expression for the standing wave signal after power transformation is expanded in the frequency domain to obtain the expression for the unbiased differential function. The distance spectrum is obtained by scaling the unbiased differential function expression at the frequency where the pulse peak is formed. The peak value of the distance spectrum is the distance from the acoustic sensor to the object to be measured.

2. The standing wave ranging method according to claim 1, characterized in that, The process of obtaining the standing wave signal expression at the origin of the microphone of the acoustic wave sensor and performing a power transform includes: The signal transmitted by the acoustic sensor to point x at time t is denoted as v. Tr (t,x), Where f(τ) is the instantaneous frequency, defined as: A, c, θ are the sound amplitude, sound velocity, phase, respectively, T represents the duration, f1 represents the lowest frequency, f N represents the highest frequency, f w represents the bandwidth f w = f N -f1, The signal reflected by the stationary object at a distance L from the acoustic sensor is denoted as v. Ref (t,x), Origin of the microphone of the acoustic wave sensor v C (t,0) = v Tr (t,0) + v R (t,0) = v C (t,0), v C (t,0) = v Tr (t,0) + v R (t,0), v C (t,0) becomes:

3. The standing wave ranging method according to claim 2, characterized in that, The step of expanding the power-transformed standing wave signal expression in the frequency domain to obtain the unbiased differential function expression includes: v C The power transformation of (t,0) is: Where C0 is the constant term of the interference.

4. A method for object edge recognition, characterized in that, include: The standing wave signal formed by the signal wave reflected by the object to be measured and the transmitted signal wave after the acoustic wave sensor transmits a signal wave to the object to be measured is obtained. Model the transmitted and reflected signals in the frequency domain; The power spectrum function is obtained based on the frequency domain model of the standing wave signal. The distance spectrum function is obtained by performing a Fourier transform on the power spectrum. Several peaks of the distance spectrum are the edge distances from the acoustic sensor to the object to be measured.

5. The object edge recognition method according to claim 4, characterized in that, The modeling of the transmitted and reflected signals in the frequency domain includes: The transmitted signal is modeled as a unit sound signal sinωt; The reflected acoustic signal of angular frequency ω in a ring of radius r and width dr at the origin x = 0 is denoted by v Ref,r,ω (t,0)dr, assuming constant gain factor and reflection phase shift over the entire frequency range, the reflected signal is modeled based on Lambert's law and inverse distance law as follows: v Refrω (t,0)dr integral, the reflection signal v Refω (t) is calculated as follows: in, 6. The object edge recognition method according to claim 5, characterized in that, The distance spectrum function is:

7. A standing wave ranging device, characterized in that, include: The standing wave signal generation module acquires the standing wave signal formed by the signal wave reflected by the object to be measured after the acoustic wave sensor transmits the signal wave to the object to be measured and the transmitted signal wave. The power transformation module obtains the expression of the standing wave signal at the origin where the microphone of the acoustic wave sensor is located and performs a power transformation. The frequency domain expansion module expands the power-transformed standing wave signal expression in the frequency domain to obtain the unbiased differential function expression; The distance spectrum calculation module scales the unbiased differential function expression at the frequency where the pulse peak is formed to obtain the distance spectrum. The peak value of the distance spectrum is the distance from the acoustic sensor to the object to be measured.

8. An object edge recognition device, characterized in that, include: The standing wave signal generation module is used in which the acoustic wave sensor transmits a signal wave to the object to be measured, and the signal wave reflected by the object to be measured forms a standing wave signal with the transmitted signal wave. The frequency domain modeling module models the transmitted and reflected signals in the frequency domain; The distance spectrum calculation module obtains the power spectrum function based on the frequency domain model of the standing wave signal, and performs a Fourier transform on the power spectrum to obtain the distance spectrum function. Several peaks of the distance spectrum are the edge distances from the acoustic sensor to the object to be measured.

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