Positioning method in long and narrow space based on specular reflection and arrival time estimation

Abstract

The invention discloses a positioning method in a long and narrow space based on specular reflection and arrival time estimation. The method comprises the following steps: arranging a microphone and a loudspeaker in a long and narrow space, transmitting a linear frequency modulation signal by using the loudspeaker, acquiring a positioning signal reflected by the wall surface of the long and narrow space by using the microphone, and filtering the acquired positioning signal to obtain signal propagation delay time; obtaining the intermediate frequency signal based on the signal propagation delay time according to the property of the frequency-modulated continuous wave may be more accurate, and then obtaining the accurate signal arrival time of the signal source by using the intermediate frequency signal; and obtaining the optimal estimation position of the target based on a maximum likelihood estimation method according to the standard signal arrival time of the signal source, and further obtaining the position information of the to-be-positioned target. According to the method, the mirror image signal source is introduced, high precision and good robustness are achieved, and accurate position estimation can be carried out on the moving target.

Description

Technical Field

[0001] The invention belongs to the technical field of indoor positioning, and in particular relates to a positioning method in a narrow and long space based on mirror reflection and arrival time estimation. Background Art

[0002] The background of positioning in narrow and long spaces stems from the challenges faced by traditional indoor positioning technologies in narrow environments. Narrow and long spaces (such as corridors or narrow roads) have unique characteristics, and signals are easily affected by multipath reflections from walls, ceilings, and the ground, resulting in signal interference and reduced positioning accuracy. Existing indoor positioning technologies, such as those based on LiDAR, UWB, WiFi, etc., usually perform poorly in these environments. For example, in a narrow and long space with a rectangular layout, the positioning accuracy of UWB will drop significantly due to the increase in the aspect ratio. In addition, technologies such as WiFi and Bluetooth can usually only provide meter-level accuracy, which cannot meet the requirements of tasks that require precise positioning, such as robot navigation and drone control.

[0003] In recent years, the application of acoustic positioning technology in indoor environments has received attention, especially in narrow and long spaces. Acoustic positioning uses a base station to send ultrasonic signals, which are received by the receiver and then the position is calculated. This technology has strong anti-interference ability, and through filtering, cross-correlation and other technical means, it can achieve high-precision positioning even in a noisy environment. Acoustic positioning technology relies on high-precision arrival time estimation. However, in a narrow and long space, the transmitted signal will be propagated to the receiving end through multiple reflections of the wall, the ground, and the ceiling. At the same time, multiple base stations in the narrow and long space will not only increase the system deployment cost, but will also further cause the receiving end to be unable to accurately solve the signal arrival time. Therefore, it is of great significance for acoustic positioning to use the mirror reflection characteristics of the acoustic signal to realize a virtual base station and use the geometric constraints of the narrow and long space to remove specific multipaths.

[0004] Some algorithms use special coding methods to improve the signal's anti-multipath capability, or use other sensors (such as IMU, etc.) to roughly estimate the device location, and use the roughly estimated location to correct the estimated arrival time. However, additional sensors often require strict data calibration and complex processing algorithms. In addition, although the use of special coding methods can deal with interference between multiple base stations to a certain extent, as the system's operating range increases and the number of deployed base stations increases, special coding schemes are still unable to cope with the interference caused by complex multipath effects in narrow and long spaces, which not only leads to poor estimation accuracy of the arrival time, but also redundant base stations also greatly increase the overall cost of the system. In summary, there is an urgent need for a method that can achieve position estimation using a single base station in a narrow and long space. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a positioning method in a narrow and long space based on mirror reflection and arrival time estimation, which does not rely on additional sensors and can accurately estimate the position of the target to be positioned.

[0006] The technical solution adopted by the present invention comprises the following steps:

[0007] Step S1, firstly, arrange a microphone and a loudspeaker in the narrow and long space, use the loudspeaker to transmit a linear frequency modulation signal, and use the microphone to collect the positioning signal reflected from the wall surface of the narrow and long space and the direct positioning signal;

[0008] The positioning signal includes the echo signal reflected by the wall of the narrow space and the direct signal directly from the speaker to the microphone.

[0009] Step S2, filtering the positioning signal in step S1 to obtain a signal propagation delay time;

[0010] Step S3, obtaining an intermediate frequency signal according to the signal propagation delay time, and then using the intermediate frequency signal to obtain the signal arrival time of the signal source;

[0011] Step S4: According to the signal arrival time of the signal source, the optimal estimated position of the target is obtained based on the maximum likelihood estimation method, and then the position information of the target to be located is obtained.

[0012] The step S1 is specifically as follows:

[0013] First, a loudspeaker is arranged on the inner wall of a long and narrow space, and a microphone is installed on a target to be located. A linear frequency modulation signal is emitted by the loudspeaker, and the linear frequency modulation signal emitted by the loudspeaker is reflected on the wall surface of the long and narrow space, so that a virtual signal source is generated outside the long and narrow space. The virtual signal source and the loudspeaker are symmetrically distributed with the inner wall of the long and narrow space as a symmetry plane, and the distance between the virtual signal source and the target is equal to the distance from the linear frequency modulation signal emitted by the loudspeaker to the reflection point on the inner wall surface of the long and narrow space plus the distance from the reflection point on the inner wall surface of the long and narrow space to the target;

[0014] The loudspeaker and the virtual signal source are both used as signal sources. The two signal sources emit their own linear frequency modulation signals to the target respectively. The signals emitted by the signal sources are propagated in the narrow space and then collected by the microphone installed on the target.

[0015] The step S2 is specifically as follows:

[0016] Step S21: first, perform bandpass filtering on the positioning signal collected in step S1, and filter out the signal in the frequency band where the linear frequency modulation signal is located from the positioning signal as the frequency band signal s r (t), frequency band signal s r The expression of (t) is as follows:

[0017]

[0018] Wherein, α represents the attenuation coefficient; f0 represents the starting frequency of the linear frequency modulation signal; B represents the bandwidth of the linear frequency modulation signal; T represents the period of the linear frequency modulation signal; π represents the circumference of a circle; t represents the time variable; t d Indicates the delay time of signal propagation;

[0019] Step S22: Then use the linear frequency modulation signal emitted by the signal source as the reference signal x(t) to obtain the filtered frequency band signal s r The cross-correlation function R between (t) and the corresponding reference signal xs (τ):

[0020]

[0021] Where, τ represents the time delay parameter;

[0022] Step S23: Finally, use the peak extraction algorithm to extract the cross-correlation function R between the frequency band signal and the reference signal. xs (τ) to extract the peak value and obtain the cross-correlation function R xs (τ) and according to the cross-correlation function R xs The peak value of (τ) is used to obtain the frequency band signal s r The time difference between (t) and the reference signal is taken as the signal propagation delay time t of the positioning signal d .

[0023] The step S3 is specifically as follows:

[0024] Step S31: First, using the signal propagation delay time t d For frequency band signal s r (t) interception: with t q -τ a As the starting time of signal interception, t d -τ a +T is the end time of signal interception for the frequency band signal s r (t) is intercepted, and the intercepted frequency band signal is used as the truncated signal s corresponding to the signal source j (t), and process it according to the following formula to obtain the intermediate frequency signal s corresponding to the signal source m (t):

[0025]

[0026] Among them, τ ais the preset interception time length; T represents the period of the linear frequency modulation signal; α represents the attenuation coefficient; f0 represents the starting frequency of the linear frequency modulation signal; B represents the bandwidth of the linear frequency modulation signal; t represents the time variable;

[0027] Step S32: IF signal s m (t) Perform fast Fourier transform so that the intermediate frequency signal s m (t) Convert the time domain signal into a frequency domain signal, and obtain each frequency peak in the frequency domain signal as a candidate frequency f p ;

[0028] In fact, the intermediate frequency signal corresponding to the loudspeaker and the intermediate frequency signal corresponding to the virtual signal source have the same form.

[0029] Step S33: Then determine each candidate frequency f p Is it qualified? Use qualified candidate frequency f p Get the standard frequency f corresponding to the speaker and the virtual signal source p ′;

[0030] Step S34: Next, according to the standard frequency f p ′According to the following formula, the signal arrival time τ is obtained k :

[0031]

[0032] Among them, τ k Indicates the time it takes for the linear FM signal emitted by the signal source to reach the microphone.

[0033] The step S33 is specifically as follows:

[0034] Step S331: First, according to the candidate frequency f p The estimated distance from the signal source to the target is obtained by the following formula:

[0035]

[0036] Among them, R O represents the estimated distance from the signal source to the target; c represents the speed of sound;

[0037] Step S332: select the candidate frequency f according to the following constraints: p To determine, the candidate frequency f p The constraints are as follows:

[0038]

[0039] R C >R O,x >R F >RO,y

[0040] f p ,x>f p ,y>0.2·f max , f p ∈{f p ,x,f p ,y}

[0041] Among them, R O,x Represents the estimated distance from the virtual signal source to the target; R O,y Represents the estimated distance from the speaker to the target; R w is the width of the narrow space; R F It represents the path length of the linear frequency modulation signal from the loudspeaker to the microphone after passing through the bottom reflection point in the narrow space; R h Indicates the distance from the speaker to the bottom of the narrow space; R l R is the distance from the speaker to the top surface of the narrow space; C It represents the path length of the linear frequency modulation signal from the loudspeaker to the microphone after passing through the top surface reflection point in the narrow space; f p ,x represents the candidate frequency of the virtual signal source corresponding to the intermediate frequency signal; f p ,y represents the candidate frequency of the speaker corresponding to the intermediate frequency signal; f max Indicates the frequency corresponding to the maximum energy peak in the intermediate frequency signal;

[0042] If the candidate frequency f p If the above constraints are met, then the candidate frequency f p is a qualified candidate frequency f p ;

[0043] Step S333: For the loudspeaker and the virtual signal source, select a qualified candidate frequency f p The minimum value among them is taken as the standard frequency f corresponding to the speaker p ′, take the qualified candidate frequency f p The second smallest value in is taken as the standard frequency f corresponding to the virtual signal source p ′.

[0044] The step S4 is specifically as follows: firstly, the estimated position of the target is obtained by processing the signal arrival time according to the following formula, and the function expression of the estimated position of the target is as follows:

[0045]

[0046] R O,y =cτ k,y

[0047] R O,x =cτ k,x

[0048] Among them, L(p T ) represents the likelihood function; p T represents the estimated position of the target, p k is the signal source position; p y Indicates the position of the speaker; p x Indicates the location of the virtual signal source; R O,k is the distance from the target to the signal source; σ is the error distribution variance; R O,y Represents the estimated distance from the speaker to the target; R O,x represents the estimated distance from the virtual signal source to the target; τ k,y represents the signal arrival time of the loudspeaker; τ k,x represents the signal arrival time of the virtual signal source; c represents the speed of sound;

[0049] Then the likelihood function L(p T ) takes the minimum target estimated position p T As the optimal estimated position of the target, the position information of the target is determined using the optimal estimated position of the target.

[0050] The expression of the linear frequency modulation signal s(t) in step S1 is as follows:

[0051]

[0052] Wherein, f0 represents the starting frequency of the linear frequency modulation signal; B represents the bandwidth of the linear frequency modulation signal; T represents the period of the linear frequency modulation signal; π represents pi; and t represents the time variable.

[0053] The present invention uses a customized frequency linear frequency modulation signal as the transmitting signal, and uses a bandpass filter to separate the signal data of the frequency band where the customized signal is located in the received signal; the propagation delay time is estimated by the cross-correlation method and combined with the peak extraction algorithm to jointly estimate the peak frequency corresponding to the signal, and the geometric constraints of the speaker and the mirror speaker in a narrow and long space are used to obtain the accurate signal arrival time, and the maximum likelihood method is used to solve the optimal position of the microphone, thereby achieving accurate position estimation of the target in complex indoor scenes.

[0054] The beneficial effects of the present invention are:

[0055] 1. The present invention performs cross-correlation processing on the received positioning signal to obtain the delay time, and intercepts the signal data for a period of time forward based on the delay time, so that the constructed intermediate frequency signal is more accurate.

[0056] 2. According to the geometric constraints unique to the narrow and long space, the present invention utilizes the loudspeaker and the mirror loudspeaker generated in the narrow and long space to screen the frequency of the intermediate frequency signal to obtain a more accurate signal arrival time.

[0057] 3. The present invention utilizes the intermediate frequency signal and the known signal source position to construct a likelihood function, and obtains the optimal position estimation of the target by minimizing the likelihood function. The method of the present invention introduces a mirror signal source, has high accuracy and good robustness, and can accurately estimate the position of a moving target.

[0058] 4. After the customized excitation signal is emitted from the loudspeaker, the present invention uses a bandpass filter to separate the received signal data with the customized signal frequency band, making the signal more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1 is a flow chart of a single base station narrow and long space positioning method of the present invention;

[0061] Figure 2 It is a waveform diagram and spectrogram of customized signal. DETAILED DESCRIPTION

[0062] The following describes the embodiments of the present invention through specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0063] The positioning method in a narrow and long space of the present invention comprises the following steps: Figure 1 As shown:

[0064] Step S1: firstly, a microphone and a loudspeaker are arranged in the narrow and long space, a customized linear frequency modulation signal is emitted by the loudspeaker, and a positioning signal reflected from the wall of the narrow and long space and a direct positioning signal are collected by the microphone;

[0065] The positioning signal includes the echo signal reflected by the wall of the narrow space and the direct signal directly from the speaker to the microphone.

[0066] Step S2, filtering the positioning signal in step S1 to obtain a signal propagation delay time;

[0067] Step S3, obtaining an intermediate frequency signal according to the signal propagation delay time, and then using the intermediate frequency signal to obtain the signal arrival time of the signal source;

[0068] Step S4: According to the signal arrival time of the signal source, the optimal estimated position of the target is obtained based on the maximum likelihood estimation method, and then the position information of the target to be located is obtained.

[0069] The narrow and long space is a horizontal narrow and long space, that is, the extension direction of the narrow and long space is parallel to the ground.

[0070] Wherein, step S1 is specifically as follows:

[0071] First, the loudspeaker is placed on the inner wall of the narrow space, and the microphone is installed on the target to be located. The target is located in the narrow space, and the loudspeaker is used to transmit the linear frequency modulation signal. The waveform and spectrum of the linear frequency modulation signal are shown in the figure below. Figure 2 As shown, the linear frequency modulation signal emitted by the loudspeaker is reflected on the wall surface of the narrow and long space, so that a virtual signal source is generated outside the narrow and long space, and the virtual signal source and the loudspeaker are symmetrically distributed with the inner wall directly opposite to the loudspeaker in the narrow and long space as the symmetry plane, and the distance between the virtual signal source and the target is equal to the distance from the linear frequency modulation signal emitted by the loudspeaker to the reflection point on the inner wall surface of the narrow and long space plus the distance from the reflection point on the inner wall surface of the narrow and long space to the target;

[0072] Both the loudspeaker and the virtual signal source are used as signal sources, where the loudspeaker is the real signal source. The signal sources include the real signal source and the virtual signal source. The two signal sources respectively emit their own linear frequency modulation signals to the target. The signals emitted by the signal sources are collected by the microphone installed on the target after propagating in the narrow space. Each signal source generates a corresponding positioning signal.

[0073] For a real signal source (such as a speaker), due to mirror reflection in a narrow space, a virtual signal source will be generated on the opposite side of the real signal source. The processing method of the virtual signal source for the signal arrival time is the same as that of the real signal source. In step S1, the customized linear frequency modulation signal is an ascending linear frequency modulation signal with a duration of 40ms, a frequency of the frequency modulation signal of 16-19kHz, a sampling frequency of 48kHz, and a signal refresh rate of 1Hz.

[0074] The expression of the linear frequency modulation signal s(t) in step S1 is as follows:

[0075]

[0076] Wherein, f0 represents the starting frequency of the linear frequency modulation signal; B represents the bandwidth of the linear frequency modulation signal; T represents the period of the linear frequency modulation signal; π represents pi; and t represents the time variable.

[0077] In the specific implementation, step S2 is specifically as follows:

[0078] Step S21: first, use a bandpass filter to perform bandpass filtering on the positioning signal collected in step S1, and filter out the signal in the frequency band where the linear frequency modulation signal is located from the positioning signal as the frequency band signal s r (t), frequency band signal s r The expression of (t) is as follows:

[0079]

[0080] Wherein, α represents the attenuation coefficient; f0 represents the starting frequency of the linear frequency modulation signal; B represents the bandwidth of the linear frequency modulation signal; T represents the period of the linear frequency modulation signal; π represents the circumference of a circle; t represents the time variable; t d Indicates the delay time of signal propagation;

[0081] Among them, the upper and lower cutoff frequencies of the bandpass filter for separating the frequency band signal are 15.9kHz and 19.1kHz respectively, and the order is 20.

[0082] Step S22: Then use the linear frequency modulation signal emitted by the signal source as the reference signal x(t) to obtain the filtered frequency band signal s r The cross-correlation function R between (t) and the corresponding reference signal xs (τ):

[0083]

[0084] Where, τ represents the time delay parameter;

[0085] Step S23: Finally, use the peak extraction algorithm to extract the cross-correlation function R between the frequency band signal and the reference signal. xs (τ) to extract the peak value and obtain the cross-correlation function R xs (τ) and according to the cross-correlation function R xs The peak value of (τ) is used to obtain the frequency band signal s r The time difference between (t) and the reference signal is taken as the signal propagation delay time t of the positioning signal d .

[0086] Specifically, step S3 is as follows:

[0087] Step S31: First, using the signal propagation delay time t d For frequency band signal s r (t) interception: with t d -τ a As the starting time of signal interception, t d -τ a +T is the end time of signal interception for the frequency band signal s r(t) is intercepted, and the intercepted frequency band signal is used as the truncated signal s corresponding to the signal source j (t), and process it according to the following formula to obtain the intermediate frequency signal s corresponding to the signal source m (t):

[0088]

[0089] Among them, τ a is the preset interception time length; T is the period of the linear frequency modulation signal, and the intermediate frequency signal is the result of the dot product of the truncated signal and the reference signal s(t); α is the attenuation coefficient; f0 is the starting frequency of the linear frequency modulation signal; B is the bandwidth of the linear frequency modulation signal; t is the time variable;

[0090] In actual signal processing systems, due to the limitations of system performance and signal causality, it is impossible to process infinitely long signals. Therefore, before multiplying the reference signal and the actual received positioning signal, it is necessary to first extract the complete audio data with linear frequency modulation signal data from the received positioning signal stream. In order to ensure the integrity of the intercepted signal, the delay time t is obtained by cross-correlating the received annoying positioning signal with the reference signal as a template. d As the benchmark, the forward interception time is τ a The signal data is t d -τ a The signal is constructed by taking time as the starting point to improve the accuracy of intermediate frequency signal calculation. Specifically, τ a 10ms is acceptable, and the intermediate frequency signal frequency is expanded to 16-20.5kHz.

[0091] Step S32: IF signal s m (t) Perform fast Fourier transform so that the intermediate frequency signal s m (t) Convert the time domain signal into a frequency domain signal, and obtain each frequency peak in the frequency domain signal as a candidate frequency f p ;

[0092] Step S33: Then determine each candidate frequency f p Is it qualified? Use qualified candidate frequency f p Get the standard frequency f corresponding to the speaker and the virtual signal source p ′;

[0093] Step S33 is specifically as follows:

[0094] Step S331: First, according to the candidate frequency f p The estimated distance from the signal source to the target is obtained by the following formula:

[0095]

[0096] Among them, R O represents the estimated distance from the signal source to the target; c represents the speed of sound;

[0097] Step S332: select the candidate frequency f according to the following constraints: p Make a judgment, candidate frequency f p The constraints are as follows:

[0098]

[0099] R C >R O,x >R F >R O,y

[0100] f p ,x>f p ,y>0.2·f max , f p ∈{f p ,x,f p ,y}

[0101] Among them, R O,x Represents the estimated distance from the virtual signal source to the target; R O,y Represents the estimated distance from the speaker to the target; R w is the width of the narrow space; R F It represents the path length of the linear frequency modulation signal from the loudspeaker to the microphone after passing through the bottom reflection point in the narrow space; R h Indicates the distance from the speaker to the bottom of the narrow space; R l R is the distance from the speaker to the top surface of the narrow space; C It represents the path length of the linear frequency modulation signal from the loudspeaker to the microphone after passing through the top surface reflection point in the narrow space. The loudspeaker and the microphone are at the same height, and the bottom surface / inner top surface reflection points in the narrow space are all reflection points on the inner wall of the narrow space; f p ,x represents the candidate frequency of the virtual signal source corresponding to the intermediate frequency signal; f p ,y represents the candidate frequency of the speaker corresponding to the intermediate frequency signal; f max Indicates the frequency corresponding to the maximum energy peak of the two intermediate frequency signals;

[0102] If the candidate frequency f p If the above constraints are met, then the candidate frequency f p is a qualified candidate frequency f p ;

[0103] Step S333: For the loudspeaker and the virtual signal source, select a qualified candidate frequency f p The minimum value among them is taken as the standard frequency f corresponding to the speaker p ′, take the qualified candidate frequency fp The second smallest value in is taken as the standard frequency f corresponding to the virtual signal source p ′.

[0104] In fact, the intermediate frequency signal corresponding to the loudspeaker and the intermediate frequency signal corresponding to the virtual signal source have the same form, so the qualified candidate frequency f under any intermediate frequency signal can be directly selected. p To obtain the standard frequency f corresponding to the speaker and the virtual signal source p ′.

[0105] Step S34: Next, according to the standard frequency f p ′According to the following formula, the signal arrival time τ is obtained k :

[0106]

[0107] Among them, τ k Indicates the time it takes for the linear FM signal emitted by the signal source to reach the microphone.

[0108] Considering that the signal transmitting source is stationary, the intermediate frequency signal can also be expressed as:

[0109]

[0110] Where R represents the distance between the signal source and the microphone;

[0111]

[0112] Here, c represents the speed of sound.

[0113] Step S4 is specifically as follows: first, the estimated position of the target is obtained according to the signal arrival time by processing according to the following formula. The function expression of the estimated position of the target is as follows:

[0114]

[0115] R O,y =cτ k,y

[0116] R O,x =cτ k,x

[0117] Among them, L(p T ) represents the likelihood function; p T represents the estimated position of the target, p k is the signal source position; p y Indicates the position of the speaker; p x Indicates the location of the virtual signal source; R O,k is the distance from the target to the signal source; σ is the error distribution variance; R O,yRepresents the estimated distance from the speaker to the target; R O,x represents the estimated distance from the virtual signal source to the target; τ k,y represents the signal arrival time of the loudspeaker; τ k,x Represents the signal arrival time of the virtual signal source, that is, τ k ∈{τ k,x ,τ k,y}; c represents the speed of sound;

[0118] Then the likelihood function L(p T ) takes the minimum target estimated position p T As the optimal estimated position of the target, the position information of the target is determined using the optimal estimated position of the target.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A positioning method in a narrow and long space based on specular reflection and arrival time estimation, characterized in that: The following steps are involved: Step S1, firstly, arrange a microphone and a loudspeaker in the narrow and long space, use the loudspeaker to transmit a linear frequency modulation signal, and use the microphone to collect the positioning signal reflected from the wall surface of the narrow and long space and the direct positioning signal; Step S2, filtering the positioning signal in step S1 to obtain a signal propagation delay time; Step S3, obtaining an intermediate frequency signal according to the signal propagation delay time, and then using the intermediate frequency signal to obtain the signal arrival time of the signal source; Step S4: According to the signal arrival time of the signal source, the optimal estimated position of the target is obtained based on the maximum likelihood estimation method, and then the position information of the target to be located is obtained.

2. The positioning method in a narrow and long space based on specular reflection and arrival time estimation according to claim 1, characterized in that: The step S1 is specifically as follows: First, a loudspeaker is arranged on the inner wall of a long and narrow space, and a microphone is installed on a target to be located. A linear frequency modulation signal is emitted by the loudspeaker, and the linear frequency modulation signal emitted by the loudspeaker is reflected on the wall surface of the long and narrow space, so that a virtual signal source is generated outside the long and narrow space. The virtual signal source and the loudspeaker are symmetrically distributed with the inner wall of the long and narrow space as a symmetry plane, and the distance between the virtual signal source and the target is equal to the distance from the linear frequency modulation signal emitted by the loudspeaker to the reflection point on the inner wall surface of the long and narrow space plus the distance from the reflection point on the inner wall surface of the long and narrow space to the target; The loudspeaker and the virtual signal source are both used as signal sources. The two signal sources emit their own linear frequency modulation signals to the target respectively. The signals emitted by the signal sources are propagated in the narrow space and then collected by the microphone installed on the target.

3. The positioning method in a narrow and long space based on specular reflection and arrival time estimation according to claim 1, characterized in that: The step S2 is specifically as follows: Step S21: first, perform bandpass filtering on the positioning signal collected in step S1, and filter out the signal in the frequency band where the linear frequency modulation signal is located from the positioning signal as the frequency band signal s r (t), frequency band signal s r The expression of (t) is as follows: Wherein, α represents the attenuation coefficient; f0 represents the starting frequency of the linear frequency modulation signal; B represents the bandwidth of the linear frequency modulation signal; T represents the period of the linear frequency modulation signal; π represents the circumference of a circle; t represents the time variable; t d Indicates the delay time of signal propagation; Step S22: Then use the linear frequency modulation signal emitted by the signal source as the reference signal x(t) to obtain the filtered frequency band signal s r The cross-correlation function R between (t) and the corresponding reference signal xs (τ): Where, τ represents the time delay parameter; Step S23: Finally, use the peak extraction algorithm to extract the cross-correlation function R between the frequency band signal and the reference signal. xs (τ) to extract the peak value and obtain the cross-correlation function R xs (τ) and according to the cross-correlation function R xs The peak value of (τ) is used to obtain the frequency band signal s r The time difference between (t) and the reference signal is taken as the signal propagation delay time t of the positioning signal d .

4. The positioning method in a narrow and long space based on specular reflection and arrival time estimation according to claim 1, characterized in that: The step S3 is specifically as follows: Step S31: First, using the signal propagation delay time t d For frequency band signal s r (t) interception: with t d -τ a As the starting time of signal interception, t d -τ a +T is the end time of signal interception for the frequency band signal s r (t) is intercepted, and the intercepted frequency band signal is used as the truncated signal s corresponding to the signal source j (t), and process it according to the following formula to obtain the intermediate frequency signal s corresponding to the signal source m (t): Among them, τ a is the preset interception time length; T represents the period of the linear frequency modulation signal; α represents the attenuation coefficient; f0 represents the starting frequency of the linear frequency modulation signal; B represents the bandwidth of the linear frequency modulation signal; t represents the time variable; Step S32: IF signal s m (t) Perform fast Fourier transform so that the intermediate frequency signal s m (t) Convert the time domain signal into a frequency domain signal, and obtain each frequency peak in the frequency domain signal as a candidate frequency f p ; Step S33: Then determine each candidate frequency f p Is it qualified? Use qualified candidate frequency f p Get the standard frequency f corresponding to the speaker and the virtual signal source p ′; Step S34: Next, according to the standard frequency f p ′According to the following formula, the signal arrival time τ is obtained k : Among them, τ k Indicates the time it takes for the linear FM signal emitted by the signal source to reach the microphone.

5. The positioning method in a narrow and long space based on specular reflection and arrival time estimation according to claim 4, characterized in that: The step S33 is specifically as follows: Step S331: First, according to the candidate frequency f p The estimated distance from the signal source to the target is obtained by the following formula: Among them, R O represents the estimated distance from the signal source to the target; c represents the speed of sound; Step S332: select the candidate frequency f according to the following constraints: p To determine, the candidate frequency f p The constraints are as follows: f p ,x>f p ,y>0.2·f max ,f p ∈{f p ,x,f p ,y} Among them, R O,x Represents the estimated distance from the virtual signal source to the target; R O,y Represents the estimated distance from the speaker to the target; R w is the width of the narrow space; R F It represents the path length of the linear frequency modulation signal from the loudspeaker to the microphone after passing through the bottom reflection point in the narrow space; R h Indicates the distance from the speaker to the bottom of the narrow space; R l R is the distance from the speaker to the top surface of the narrow space; C It represents the path length of the linear frequency modulation signal from the loudspeaker to the microphone after passing through the top surface reflection point in the narrow space; f p ,x represents the candidate frequency of the virtual signal source corresponding to the intermediate frequency signal; f p ,y represents the candidate frequency of the speaker corresponding to the intermediate frequency signal; f max Indicates the frequency corresponding to the maximum energy peak in the intermediate frequency signal; If the candidate frequency f p If the above constraints are met, then the candidate frequency f p is a qualified candidate frequency f p ; Step S333: For the loudspeaker and the virtual signal source, select a qualified candidate frequency f p The minimum value among them is taken as the standard frequency f corresponding to the speaker p ′, take the qualified candidate frequency f p The second smallest value in is taken as the standard frequency f corresponding to the virtual signal source p ′.

6. The positioning method in a narrow and long space based on specular reflection and arrival time estimation according to claim 1, characterized in that: The step S4 is specifically as follows: firstly, the estimated position of the target is obtained by processing the signal arrival time according to the following formula, and the function expression of the estimated position of the target is as follows: R O,y =cτ k,y R O,x =cτ k,x Among them, L(p T ) represents the likelihood function; p T represents the estimated position of the target, p k is the signal source position; p y Indicates the position of the speaker; p x Indicates the location of the virtual signal source; R O,k is the distance from the target to the signal source; σ is the error distribution variance; R O,y Represents the estimated distance from the speaker to the target; R O,x represents the estimated distance from the virtual signal source to the target; τ k,y represents the signal arrival time of the loudspeaker; τ k,x represents the signal arrival time of the virtual signal source; c represents the speed of sound; Then the likelihood function L(p T ) takes the minimum target estimated position p T As the optimal estimated position of the target, the position information of the target is determined using the optimal estimated position of the target.

7. The positioning method in a narrow and long space based on specular reflection and arrival time estimation according to claim 1, characterized in that: The expression of the linear frequency modulation signal s(t) in step S1 is as follows: Wherein, f0 represents the starting frequency of the linear frequency modulation signal; B represents the bandwidth of the linear frequency modulation signal; T represents the period of the linear frequency modulation signal; π represents pi; and t represents the time variable.

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