A phase ranging method and apparatus

Abstract

This application discloses a phase ranging method and apparatus, applicable to the field of ranging. The phase ranging method provided in this application involves mixing two laser ruler modulation frequency signals and local oscillator frequency signals to obtain the difference frequency signals corresponding to the laser rulers; performing analog-to-digital conversion on the different difference frequency signals to obtain the corresponding digital signals; processing the digital signals using a dual phase-locked loop (PLL) circuit chip to obtain the corresponding frequency signals; and determining a third frequency signal based on the difference between the two frequency signals; determining the phase difference between the first and third frequency signals; and determining the measurement distance data corresponding to the phase difference according to a preset correspondence. This application uses a first and third frequency with a large phase difference in the calculation process, reducing the attenuation effect caused by different devices receiving frequencies with large phase differences, and calculating the phase difference corresponding to both the first and third frequencies, thereby improving the accuracy of ranging.

Description

Technical Field

[0001] This application relates to the field of ranging, and in particular to a phase ranging method and apparatus. Background Technology

[0002] With societal development and the increasing demands for intelligent systems across industries, the application of laser ranging technology is becoming increasingly widespread. Currently, laser ranging is used in numerous fields, including aviation, military, and construction.

[0003] In recent years, the phase method, as a high-precision measurement method in laser ranging, can achieve accuracy at the millimeter level and is widely used in surveying fields where high measurement accuracy is required but ranging speed is low. However, its application is limited due to its low ranging speed. In the currently booming fields of lidar applications, such as AGVs (Automated Guided Vehicles), drone patrols, and robotics, the pulse method is commonly used. Although the pulse method has a relatively high ranging speed, its accuracy is only at the centimeter level. The triangulation method can achieve millimeter-level accuracy at close range, but because it uses an off-axis optical system imaging principle, there is an inverse relationship between resolution and distance. While the close-range resolution is high, the resolution gradually deteriorates at medium and long distances, thus making it impossible to obtain consistently high measurement accuracy.

[0004] Given the above-mentioned technologies, finding a method that is both high-speed and maintains high ranging accuracy is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a phase ranging method and apparatus that enables high-speed and high-precision ranging.

[0006] To address the aforementioned technical problems, this application provides a phase ranging method, comprising:

[0007] The modulation frequency signal and local oscillator frequency signal of the first laser ruler and the second laser ruler are mixed respectively to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

[0008] The first difference frequency signal and the second difference frequency signal are respectively converted from analog to digital to obtain the corresponding first digital signal and second digital signal;

[0009] The first and second digital signals are processed by a dual phase-locked loop circuit chip to obtain the corresponding first and second frequency signals, and the third frequency signal is determined based on the difference between the first and second frequency signals.

[0010] Determine the phase difference between the reference frequency signal and the measured frequency signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain the first phase difference and the second phase difference;

[0011] The measurement distance data corresponding to the first phase difference and the second phase difference are determined according to the preset correspondence.

[0012] Preferably, the modulation frequency signal and local oscillator frequency signal of the first laser ruler and the second laser ruler are mixed respectively to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler, including:

[0013] The modulation frequency signal and local oscillator frequency signal of the first laser ruler and the second laser ruler are mixed respectively to obtain the first mixed signal of the first laser ruler and the second mixed signal of the second laser ruler.

[0014] The first and second mixed signals are filtered respectively to extract the difference frequency signal from the first and second mixed signals, thus obtaining the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

[0015] Preferably, filtering is performed on the first mixing signal and the second mixing signal respectively to extract the difference frequency signal from the first mixing signal and the difference frequency signal from the second mixing signal, including:

[0016] The first and second mixed signals are filtered using a low-pass filter and a transimpedance amplifier, respectively, to extract the difference frequency signal from the first and second mixed signals.

[0017] Preferably, before performing analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively, the method further includes:

[0018] The first and second difference frequency signals are amplified using a bandpass filter amplifier.

[0019] Preferably, it further includes:

[0020] Amplitude modulation is performed on the laser tube in any laser ruler using a first frequency signal and a third frequency signal;

[0021] Wherein, the frequency difference between the first frequency signal and the second frequency signal is no greater than one-tenth of the frequency of the first frequency signal.

[0022] Preferably, determining the phase difference between the reference frequency signal and the measurement frequency signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain the first phase difference and the second phase difference includes:

[0023] Determine the first reference frequency signal and the first measurement frequency signal corresponding to the first frequency signal, and the second reference frequency signal and the second measurement frequency signal corresponding to the third frequency signal;

[0024] A first phase difference is obtained based on the difference between the phase of the first reference frequency signal and the phase of the first measurement frequency signal, and a second phase difference is obtained based on the difference between the phase of the second reference frequency signal and the phase of the second measurement frequency signal.

[0025] Preferably, it further includes:

[0026] Construct a sine wave and a cosine wave with the same frequency as the target frequency signal; the target frequency signal is any one of the first measurement frequency signal, the first reference frequency signal, the second measurement frequency signal, and the second reference frequency signal.

[0027] The first constant term containing the phase of the target frequency signal is determined by multiplying the sinusoidal signal with the target frequency signal.

[0028] The second constant term, which contains the phase of the target frequency signal, is determined by multiplying the cosine signal with the target frequency signal.

[0029] The phase of the target frequency signal is determined based on the correspondence between the first and second constant terms and the trigonometric functions.

[0030] To address the aforementioned problems, this application also provides a phase ranging device, comprising:

[0031] A mixer is used to mix the modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler respectively to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

[0032] The analog-to-digital conversion module is used to perform analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively to obtain the corresponding first digital signal and second digital signal;

[0033] A dual phase-locked loop circuit chip is used to process a first digital signal and a second digital signal to obtain corresponding first frequency signals and second frequency signals, and to determine a third frequency signal based on the difference between the first frequency signal and the second frequency signal.

[0034] The controller is used to determine the phase difference between the reference frequency signal and the measurement frequency signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain the first phase difference and the second phase difference; and to determine the measurement distance data corresponding to the first phase difference and the second phase difference according to the preset correspondence.

[0035] Preferably, the mixer includes:

[0036] The mixing unit is used to mix the modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler respectively to obtain the first mixed signal of the first laser ruler and the second mixed signal of the second laser ruler.

[0037] The filtering unit is used to filter the first mixing signal and the second mixing signal respectively to extract the difference frequency signal in the first mixing signal and the difference frequency signal in the second mixing signal, so as to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

[0038] Preferably, it further includes:

[0039] A bandpass filter amplifier is used to amplify the first difference frequency signal and the second difference frequency signal.

[0040] The phase ranging method provided in this application includes: mixing the modulation frequency signal and the local oscillator frequency signal of a first laser ruler and a second laser ruler respectively to obtain a first difference frequency signal of the first laser ruler and a second difference frequency signal of the second laser ruler; performing analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively to obtain corresponding first digital signal and second digital signal; processing the first digital signal and the second digital signal based on a dual phase-locked loop circuit chip to obtain corresponding first frequency signal and second frequency signal, and determining a third frequency signal based on the difference between the first frequency signal and the second frequency signal; determining the phase difference between a reference frequency signal and a measurement frequency signal corresponding to the first frequency signal and the third frequency signal respectively to obtain a first phase difference and a second phase difference; and determining the measurement distance data corresponding to the first phase difference and the second phase difference according to a preset correspondence. This application uses a first frequency and a second frequency for frequency ranging, but uses a first frequency and a third frequency for distance calculation. The third frequency is determined based on the difference between the first frequency and the second frequency. By using the first frequency and the third frequency, which have a large phase difference, this application reduces the attenuation effect caused by different devices receiving frequencies with large phase differences. Furthermore, it calculates the phase difference corresponding to the first frequency and the third frequency respectively, thereby improving the accuracy of ranging. Attached Figure Description

[0041] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A flowchart of a phase ranging method provided in an embodiment of this application;

[0043] Figure 2 A waveform diagram of the direct scale modulation frequency signal provided in an embodiment of this application;

[0044] Figure 3 A waveform diagram of the indirect measuring scale modulation frequency signal provided in an embodiment of this application;

[0045] Figure 4 This is a diagram of the internal structure of the MS5351 chip provided in an embodiment of this application;

[0046] Figure 5 A graph showing the relationship between the module's measured values ​​and the actual values ​​provided in the embodiments of this application;

[0047] Figure 6 A graph showing the relationship between module measurement error and distance provided in an embodiment of this application;

[0048] Figure 7 A structural diagram of a phase ranging device provided in another embodiment of this application;

[0049] Figure 8 The overall flowchart of the phase ranging method provided in the embodiments of this application is shown. Detailed Implementation

[0050] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0051] The core of this application is to provide a phase ranging method and apparatus.

[0052] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Figure 1 A phase ranging method provided in this application includes the following steps:

[0054] S10: Mix the modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler respectively to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

[0055] In a specific embodiment, the local oscillator frequency signal is related to the performance data of the laser ruler itself, while the modulation frequency signal is related to the environment in which the laser ruler is currently used, and is adjusted by the user.

[0056] In this process, the modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler are mixed to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler. The higher frequency signal needs to be filtered out in the difference frequency signal to facilitate analog-to-digital conversion.

[0057] It should be noted that frequency mixing can be performed using a mixer or other devices that can achieve the same function. This application is not limited to any particular device and users can configure it according to their needs.

[0058] S11: Perform analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively to obtain the corresponding first digital signal and second digital signal.

[0059] In a specific embodiment, the first difference frequency signal and the second difference frequency signal obtained after mixing are subjected to analog-to-digital conversion to convert the analog signal into a digital signal, thereby obtaining the corresponding first digital signal and second digital signal, which facilitates subsequent calculations.

[0060] It should be noted that analog-to-digital conversion can be performed using an analog-to-digital converter (ADC) or other analog-to-digital conversion modules. This application is not limited to either ADC or other analog-to-digital conversion modules, and users can configure them according to their needs.

[0061] S12: The first digital signal and the second digital signal are processed based on the dual phase-locked loop circuit chip to obtain the corresponding first frequency signal and second frequency signal, and the third frequency signal is determined based on the difference between the first frequency signal and the second frequency signal.

[0062] In a specific embodiment, a chip with a dual phase-locked loop (PLL) circuit is used to phase-lock and process the first and second digital signals respectively. The dual PLL circuit can simultaneously phase-lock signals of different frequencies without switching back and forth, thus improving the final ranging speed. The first and second frequency signals are obtained from the chip with the dual PLL circuit, and a third frequency signal is determined based on the difference between the first and second frequency signals.

[0063] In this distance measurement formula, to measure a distance of 10m within one cycle, a measuring scale length of 10m is required, corresponding to a modulation frequency signal of 15MHz. However, accuracy must be considered. For example, if the phase calculation accuracy is 1°, the corresponding distance resolution is 10000mm / 360 = 27.78mm, which clearly does not meet the millimeter-level accuracy requirement. Therefore, to improve accuracy, a higher frequency of 150MHz is selected, with a corresponding measuring scale length of 1m. Still using a 1° phase calculation, the resolution becomes 1000mm / 360 = 2.778mm. Finally, different accuracy levels are used to connect the measured distances to obtain the final distance. The modulation frequency is as follows... Figure 2 As shown and according to Figure 2 It can be seen that 15MHz and 150MHz are quite different. When the same device receives frequency signals with significantly different frequencies, the resulting attenuation and impact will be different.

[0064] To address the issue of large amplitude-frequency response of electronic components due to different modulation frequencies, an indirect measuring method is proposed. Direct measuring uses 150MHz and 150*0.1 = 15MHz, while indirect measuring uses 150MHz and 150MHz - 150MHz*0.1 = 135MHz as two sets of ranging frequencies. Figure 3 As shown, when two sets of frequencies differing by only 1 / 10 are used to modulate the laser tube, the amplitude difference of the low-frequency signal received by the APD, after passing through the transimpedance amplifier and bandpass filter, and finally sampled by the MCU, will be very small. This ensures that both sets of ranging frequencies achieve the same level of phase calculation accuracy. In the indirect measuring scheme, the high-precision measuring range is determined by 150MHz, while the low-precision measuring range is determined by: 150MHz - 135MHz = 15MHz. That is, the phase difference between the two sets of measuring ranges is used as the phase difference of the low-frequency measuring range. Because it is not a direct measurement result, but rather uses the difference as the measuring range, it is called "indirect measuring."

[0065] The dual phase-locked loop (PLL) circuit chip can be an MS5351, etc., and this application is not limited to it. Users can choose their own chip based on their needs. The internal structure diagram of the MS5351 is shown below. Figure 4 As shown, this chip features three-channel output, clock speeds from 2.5kHz to 200MHz; output frequency error: 0ppm; high resolution, low jitter; can operate on 25MHz or 27MHz quartz crystal or direct OSC input; adjustable output clock phase; glitches-free frequency output switching; internal core power supply voltage VDD: 2.5V / 3.3V; output stage power supply VDDIO: 1.8V / 2.5V / 3.3V.

[0066] It should be noted that the specific values ​​in the examples are only one possible way to achieve this, but are not the only possible way. Users can choose according to their needs.

[0067] S13: Determine the phase difference between the reference frequency signal and the measurement frequency signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain the first phase difference and the second phase difference.

[0068] In a specific embodiment, the phase difference between the reference frequency signal and the corresponding measurement frequency signal can be determined through certain calculations.

[0069] The calculation method is not limited in this application and can be set by the user according to their needs.

[0070] S14: Determine the measurement distance data corresponding to the first phase difference and the second phase difference according to the preset correspondence.

[0071] The first frequency signal corresponds to the first phase difference and the first laser ruler, while the third frequency signal corresponds to the second phase difference and the second laser ruler. The measurement distance can be determined based on the preset correspondence with the first and second phase differences, and the corresponding laser rulers can be connected.

[0072] The phase ranging method provided in this application includes: mixing the modulation frequency signal and the local oscillator frequency signal of a first laser ruler and a second laser ruler respectively to obtain a first difference frequency signal of the first laser ruler and a second difference frequency signal of the second laser ruler; performing analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively to obtain corresponding first digital signal and second digital signal; processing the first digital signal and the second digital signal based on a dual phase-locked loop circuit chip to obtain corresponding first frequency signal and second frequency signal, and determining a third frequency signal based on the difference between the first frequency signal and the second frequency signal; determining the phase difference between a reference frequency signal and a measurement frequency signal corresponding to the first frequency signal and the third frequency signal respectively to obtain a first phase difference and a second phase difference; and determining the measurement distance data corresponding to the first phase difference and the second phase difference according to a preset correspondence. This application uses a first frequency and a second frequency for frequency ranging, but uses a first frequency and a third frequency for distance calculation. The third frequency is determined based on the difference between the first frequency and the second frequency. By using the first frequency and the third frequency, which have a large phase difference, this application reduces the attenuation effect caused by different devices receiving frequencies with large phase differences. Furthermore, it calculates the phase difference corresponding to the first frequency and the third frequency respectively, thereby improving the accuracy of ranging.

[0073] Based on the above embodiments, as a preferred embodiment, the modulation frequency signal and local oscillator frequency signal of the first laser ruler and the second laser ruler are mixed to obtain a first difference frequency signal of the first laser ruler and a second difference frequency signal of the second laser ruler, including:

[0074] The modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler are mixed respectively to obtain the first mixed signal of the first laser ruler and the second mixed signal of the second laser ruler.

[0075] The first mixing signal and the second mixing signal are filtered respectively to extract the difference frequency signal in the first mixing signal and the difference frequency signal in the second mixing signal, so as to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

[0076] Specifically, a low-pass filter and a transimpedance amplifier are used to filter the first and second mixing signals respectively, so as to extract the difference frequency signal in the first and second mixing signals.

[0077] In a specific embodiment, the modulation frequency signal and the local oscillator frequency signal of any laser ruler are mixed by a mixer to obtain a corresponding mixed signal. The mixed signal includes a sum frequency signal and a difference frequency signal. The sum frequency signal has a higher frequency and requires filtering by a low-pass filter and a transimpedance amplifier to extract the required difference frequency signal. Through this process, the frequency of the signal can be reduced while ensuring that the phase remains unchanged. It is easier to convert the analog signal into a digital signal by using a lower-cost, low-speed analog-to-digital converter (ADC). A general-purpose MCU integrated ADC can be used, and this application is not limited to this.

[0078] Taking the first laser ruler as an example:

[0079] The modulation frequency signal of the first laser ruler:

[0080] The local oscillator frequency signal of the first laser ruler:

[0081] The first mixed signal obtained through frequency mixing

[0082]

[0083] First difference frequency signal:

[0084] Where KM is the gain coefficient, cos is a trigonometric function, t is time, ω1 is the angular frequency of the tuning frequency signal, and ω2 is the angular frequency of the local oscillator frequency signal. The initial phase of the modulation frequency signal, U is the initial phase of the local oscillator frequency signal. m1 U is the amplitude of the modulation frequency signal. m2 This refers to the amplitude of the local oscillator frequency signal. This application does not limit this; users can adjust it themselves according to their needs and equipment requirements.

[0085] It should be noted that the frequency signal in the example is only one possible implementation method, but it is not the only one. Users can set it themselves according to their needs.

[0086] It should also be noted that using a low-pass filter and a transimpedance amplifier for filtering is only one possible method, but it is not the only one. Users can configure it according to their needs.

[0087] This application reduces the signal frequency while maintaining the phase by mixing and filtering the local oscillator frequency signal and the modulation frequency signal, making it easier for the analog-to-digital converter (ADC) to sample and convert the analog signal into a digital signal. It can use the ADC integrated on the chip of a general-purpose MCU, without any restrictions on the ADC's functional requirements or model.

[0088] Based on the above embodiments, as a preferred embodiment, before performing analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal, the method further includes:

[0089] The first and second difference frequency signals are amplified using a bandpass filter amplifier.

[0090] In practice, the first and second difference frequency signals need to be amplified by a bandpass filter amplifier for subsequent analog-to-digital conversion.

[0091] Based on the above embodiments, as a preferred embodiment, it further includes:

[0092] Amplitude modulation is performed on the laser tube in any laser ruler using a first frequency signal and a third frequency signal;

[0093] Wherein, the frequency difference between the first frequency signal and the second frequency signal is no greater than one-tenth of the frequency of the first frequency signal.

[0094] In a specific embodiment, the laser tube is controlled by a corresponding frequency signal to achieve the desired effect.

[0095] Wherein, the frequency difference between the first frequency signal and the second frequency signal is no greater than one-tenth of the first frequency signal. For example, the first frequency signal is 150MHz and the second frequency signal is 135MHz. Wherein, the frequency difference between the first frequency signal and the second frequency signal is no greater than one-tenth of the first frequency signal. That is, at this frequency, the difference between the first frequency signal and the second frequency signal is 15MHz, which means the third frequency signal is 15MHz. This application adopts this method to reduce the large attenuation that occurs when frequencies with large differences are received by the same device, thus affecting subsequent calculations.

[0096] It should be noted that one-tenth is just one possible way to achieve this, but it is not the only way. Users can set it according to their needs.

[0097] Based on the above embodiments, as a preferred embodiment, determining the phase difference between the reference frequency signal and the measurement signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain the first phase difference and the second phase difference includes:

[0098] Determine the first reference frequency signal and the first measurement frequency signal corresponding to the first frequency signal, and the second reference frequency signal and the second measurement frequency signal corresponding to the third frequency signal;

[0099] A first phase difference is obtained based on the difference between the phase of the first reference frequency signal and the phase of the first measurement frequency signal, and a second phase difference is obtained based on the difference between the phase of the second reference frequency signal and the phase of the second measurement frequency signal.

[0100] In a specific embodiment, determining the phase difference first requires a frequency signal and corresponding reference frequency signal and measurement frequency signal. Therefore, firstly, a first reference frequency signal and a first measurement signal corresponding to the first frequency signal are determined, as well as a second reference frequency signal and a second measurement frequency signal corresponding to the third frequency signal. A first phase difference is obtained based on the difference between the phase of the first reference frequency signal and the phase of the first measurement frequency signal, and a second phase difference is obtained based on the difference between the phase of the second reference frequency signal and the phase of the second measurement frequency signal. Finally, the ranging is determined based on the first phase difference and the second phase difference.

[0101] For example, the first measurement frequency signal and the first reference frequency signal are used:

[0102] First measurement frequency signal: S = A0 + B0cos(2πft + φ0);

[0103] First reference frequency signal: R = A1 + B1cos(2πft + φ1).

[0104] Where A0 is the DC component of the measured frequency signal, B0 is the modulation index of the measured frequency signal, f is the modulation frequency, t is the time, φ0 is the initial phase, A1 is the DC component of the reference frequency signal, and B1 is the modulation index of the reference signal.

[0105] It should also be noted that the first measurement frequency signal and the first reference frequency signal are only one possible implementation method, but are not limited to this one implementation method. Users can set them according to their own needs.

[0106] Based on the above embodiments, as a preferred embodiment, it further includes:

[0107] Construct a sine wave and a cosine wave with the same frequency as the target frequency signal; the target frequency signal is any one of the first measurement frequency signal, the first reference frequency signal, the second measurement frequency signal, and the second reference frequency signal.

[0108] The first constant term containing the phase of the target frequency signal is determined by multiplying the sinusoidal signal with the target frequency signal.

[0109] The second constant term, which contains the phase of the target frequency signal, is determined by multiplying the cosine signal with the target frequency signal.

[0110] The phase of the target frequency signal is determined based on the correspondence between the first and second constant terms and the trigonometric functions.

[0111] In a specific embodiment, for example:

[0112] First measurement frequency signal: S = A0 + B0cos(2πft + φ0);

[0113] Construct a sinusoidal signal with the same frequency as the first measurement frequency signal and multiply it by the first measurement frequency signal:

[0114]

[0115] Similarly, construct a cosine signal with the same frequency as the first measurement frequency signal, and multiply it by the first measurement frequency signal:

[0116]

[0117] The phase of the first measured frequency signal: Where atan is the arctangent function;

[0118] Similarly, the first reference frequency signal is: R = A1 + B1cos(2πft + φ1);

[0119] The phase of the corresponding first reference frequency signal:

[0120] Therefore, the first phase difference is: Δφ = φ1 - φ0.

[0121] It should be noted that the specific values ​​in the examples are only one possible way to achieve this, but are not limited to this method. This application does not limit the methods and users can set them according to their needs.

[0122] In this application, a laser ruler with an accuracy of + / -1mm is used as a reference, and the data obtained are as follows: Figure 5 As shown, the module's measurement results exhibit high linearity compared to the laser ruler. Plotting the difference between the two measurements against distance yields the error versus distance curve, as shown below. Figure 6 As shown, a measurement error of + / -3mm can be obtained throughout the entire ranging range, and the ranging speed can reach over 500Hz, verifying the feasibility of this application.

[0123] In the above embodiments, the phase ranging method has been described in detail. This application also provides embodiments corresponding to the phase ranging device. It should be noted that this application describes the embodiments of the device from two perspectives.

[0124] To address the aforementioned problems, this application also provides a phase ranging device, such as... Figure 7 As shown, it includes:

[0125] A mixer is used to mix the modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler respectively to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

[0126] The analog-to-digital conversion module is used to perform analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively to obtain the corresponding first digital signal and second digital signal;

[0127] A dual phase-locked loop circuit chip is used to process a first digital signal and a second digital signal to obtain corresponding first frequency signals and second frequency signals, and to determine a third frequency signal based on the difference between the first frequency signal and the second frequency signal.

[0128] The controller is used to determine the phase difference between the reference frequency signal and the measurement frequency signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain the first phase difference and the second phase difference; and to determine the measurement distance data corresponding to the first phase difference and the second phase difference according to the preset correspondence.

[0129] The mixer includes:

[0130] The mixing unit is used to mix the modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler respectively to obtain the first mixed signal of the first laser ruler and the second mixed signal of the second laser ruler.

[0131] The filtering unit is used to filter the first mixing signal and the second mixing signal respectively to extract the difference frequency signal in the first mixing signal and the difference frequency signal in the second mixing signal, so as to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

[0132] The phase ranging device also includes a bandpass filter amplifier for amplifying the first difference frequency signal and the second difference frequency signal.

[0133] Overall ranging process: After the controller is initialized, it is connected via I... 2C sets the frequencies of MS5351#1 to Fm1 = 150MHz, Fm2 = 135MHz, FL1 = 149.995MHz, and FL2 = 134.995MHz, and sets the optical power of the laser diode (LD) and the reverse operating voltage of the avalanche diode (APD). The selector is set to S1 = H, the modulation frequency of Fm1 is 150MHz, and the local oscillator frequency of FL1 is 149.995MHz. On one hand, Fm1 and FL1 are mixed in the mixer; on the other hand, the optical signal from Fm1 received by FL1 and the current signal converted by the APD are mixed on the APD to obtain the reference signal R1 = Fm1 - FL1 and the measurement signal M1 = Fm1 - FL1. The controller uses its built-in analog-to-digital converter (ADC) to acquire the R1 and M1 signals respectively and calculate the phase difference. When the selector selects S1=L, the modulation frequency of Fm2 is 130MHz, and the local oscillator frequency of FL1 is 134.995MHz. On one hand, Fm2 and FL2 are mixed in the mixer; on the other hand, FL2 and the current signal converted from the Fm2 optical signal received by the APD are mixed on the APD to obtain the reference signal R2=Fm2-FL2 and the measurement signal M2=Fm2-FL2. The controller uses its built-in ADC to acquire the R2 and M2 signals respectively, calculates the phase difference, and obtains the phase difference. Through phase difference We can obtain the phase difference corresponding to the coarse scale frequency Fm1-Fm2; with the fine scale phase difference... Phase difference with coarse ruler: The distances corresponding to the precision ruler and the coarse ruler are obtained; through the connection algorithm, the accurate target distance can be obtained.

[0134] It should be noted that the frequency data and chip type in the overall ranging process are only one possible implementation method, but are not limited to this one. Users can set them according to their own needs.

[0135] In this application, the modulation frequency signal and the local oscillator frequency signal use different PLL chips, achieving better isolation and minimizing crosstalk between the two frequency signals. This is because the largest error in phase-based ranging schemes originates from crosstalk at the same frequency, which is one of the reasons why relatively large periodic errors easily occur in absolute measurement accuracy. To simultaneously meet the requirements of accuracy and range, a method of using two sets of ranging frequencies is adopted. The two sets of ranging frequencies are simultaneously phase-locked, which reduces frequency switching time and speeds up ranging. This is because the phase-locked frequency configuration requires the controller to communicate via I / O. 2Writing the configuration register value to the MS5351 takes at least 3ms, which significantly reduces the performance of the ranging frequency. Building upon this approach, using an external mixer allows for simultaneous measurement of two frequencies, doubling the ranging speed. The use of an "indirect measurement" method minimizes the impact of the device's frequency response characteristics, resulting in better consistency between high and low frequency ranging errors. Furthermore, the phase ranging calculation method does not employ the traditional Fast Fourier Transform (FFT) because FFT calculations require a specific number of points, such as 2... N The computational load is also large, so we directly adopt the expression for the fundamental frequency from the expansion of the Fourier formula, which is the theoretical basis for coherent demodulation; because the frequency we want to measure is known. We directly demodulate this frequency, and using the controller's built-in MAC, we can efficiently complete the phase calculation.

[0136] Since the embodiments of the apparatus and the embodiments of the method correspond to each other, please refer to the description of the embodiments of the method for the embodiments of the apparatus, which will not be repeated here.

[0137] In summary, the overall process of the phase ranging method includes the following steps, as described in the above embodiments: Figure 8 As shown:

[0138] S20: Module powered on.

[0139] S21: Microcontroller initialization, I / O port settings.

[0140] S22: Assign configuration chips #1, #2, and frequency signals via a preset protocol.

[0141] S23: Set the power and bias voltage of the corresponding diode.

[0142] S24: The selector selects the first frequency signal.

[0143] S25: Acquire and calculate the first phase difference.

[0144] S26: The selector selects the third frequency signal.

[0145] S27: Acquire and calculate the second phase difference.

[0146] S28: Corresponding measuring scale connection.

[0147] S29: Serial port output data.

[0148] S30: End.

[0149] S20-S23 are all preparatory work before ranging, S24-S26 are the ranging process, and S28-S29 are the output data and connection process.

[0150] S24-S26: The modulation frequency signal and local oscillator frequency signal of the first laser ruler and the second laser ruler are mixed respectively to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler; the first difference frequency signal and the second difference frequency signal are converted from analog to digital to obtain the corresponding first digital signal and the second digital signal; the first digital signal and the second digital signal are processed based on the dual phase-locked loop circuit chip to obtain the corresponding first frequency signal and the second frequency signal, and a third frequency signal is determined based on the difference between the first frequency signal and the second frequency signal; the phase difference between the reference frequency signal and the measurement frequency signal corresponding to the first frequency signal and the third frequency signal respectively is determined to obtain the first phase difference and the second phase difference.

[0151] It should also be noted that this application uses a dual measuring scale method, which can ensure accuracy while increasing the measuring range. Of course, if the measuring distance is relatively short, such as a drop-proof distance sensor with high accuracy requirements of + / -3mm and a measuring range of 0.05m to 1m, a single measuring scale can meet the requirements. Correspondingly, the above embodiments can be appropriately modified, and this application is not limited to this.

[0152] This application provides a phase ranging device, comprising: a mixer for mixing the modulation frequency signal and the local oscillator frequency signal of a first laser ruler and a second laser ruler respectively to obtain a first difference frequency signal of the first laser ruler and a second difference frequency signal of the second laser ruler; an analog-to-digital conversion module for performing analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively to obtain corresponding first digital signal and second digital signal; a dual phase-locked loop circuit chip for processing the first digital signal and the second digital signal to obtain corresponding first frequency signal and second frequency signal, and determining a third frequency signal based on the difference between the first frequency signal and the second frequency signal; a controller for determining the phase difference between a reference frequency signal and a measurement frequency signal corresponding to the first frequency signal and the third frequency signal respectively to obtain a first phase difference and a second phase difference; and determining the measurement distance data corresponding to the first phase difference and the second phase difference according to a preset correspondence. This application uses a first frequency and a second frequency for frequency ranging, but uses a first frequency and a third frequency for distance calculation. The third frequency is determined based on the difference between the first frequency and the second frequency. By using the first frequency and the third frequency, which have a large phase difference, this application reduces the attenuation effect caused by different devices receiving frequencies with large phase differences. Furthermore, it calculates the phase difference corresponding to the first frequency and the third frequency respectively, thereby improving the accuracy of ranging.

[0153] The phase ranging method and apparatus provided in this application have been described in detail above. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0154] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A phase ranging method, characterized in that, include: The modulation frequency signal and local oscillator frequency signal of the first laser ruler and the second laser ruler are mixed respectively to obtain the first mixed signal of the first laser ruler and the second mixed signal of the second laser ruler. The first mixing signal and the second mixing signal are filtered by a low-pass filter and a transimpedance amplifier respectively to extract the difference frequency signal in the first mixing signal and the difference frequency signal in the second mixing signal, so as to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler. The first difference frequency signal and the second difference frequency signal are converted from analog to digital using an analog-to-digital converter to obtain the corresponding first digital signal and second digital signal. The first digital signal and the second digital signal are processed by a dual phase-locked loop circuit chip to obtain a first frequency signal and a second frequency signal, and a third frequency signal is determined based on the difference between the first frequency signal and the second frequency signal; wherein the frequency difference between the first frequency signal and the second frequency signal is no greater than one-tenth of the first frequency signal. Determine the phase difference between the reference frequency signal and the measured frequency signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain the first phase difference and the second phase difference; The measurement distance data corresponding to the first phase difference and the second phase difference are determined according to the preset correspondence.

2. The phase ranging method according to claim 1, characterized in that, Before performing analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively, the method further includes: The first difference frequency signal and the second difference frequency signal are amplified using a bandpass filter amplifier.

3. The phase ranging method according to claim 1, characterized in that, Also includes: The first frequency signal and the third frequency signal are used to modulate the amplitude of the laser tube in any laser ruler.

4. The phase ranging method according to any one of claims 1 to 3, characterized in that, The step of determining the phase difference between the reference frequency signal and the measured frequency signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain the first phase difference and the second phase difference includes: Determine a first reference frequency signal and a first measurement frequency signal corresponding to the first frequency signal, and a second reference frequency signal and a second measurement frequency signal corresponding to the third frequency signal; The first phase difference is obtained based on the difference between the phase of the first reference frequency signal and the phase of the first measurement frequency signal, and the second phase difference is obtained based on the difference between the phase of the second reference frequency signal and the phase of the second measurement frequency signal.

5. The phase ranging method according to claim 4, characterized in that, Also includes: Construct a sine wave and a cosine wave with the same frequency as the target frequency signal; the target frequency signal is any one of the first measured frequency signal, the first reference frequency signal, the second measured frequency signal, and the second reference frequency signal; A first constant term containing the phase of the target frequency signal is determined by using the product between the sinusoidal signal and the target frequency signal; A second constant term containing the phase of the target frequency signal is determined by using the product between the cosine signal and the target frequency signal; The phase of the target frequency signal is determined based on the correspondence between the first and second constant terms and trigonometric functions.

6. A phase ranging device, characterized in that, include: A mixer is used to mix the modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler respectively to obtain the first mixed signal of the first laser ruler and the second mixed signal of the second laser ruler. The first mixing signal and the second mixing signal are filtered by a low-pass filter and a transimpedance amplifier respectively to extract the difference frequency signal in the first mixing signal and the difference frequency signal in the second mixing signal, so as to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler. The analog-to-digital conversion module is used to perform analog-to-digital conversion on the first difference frequency signal and the second difference frequency signal respectively using an analog-to-digital converter to obtain the corresponding first digital signal and second digital signal; A dual phase-locked loop (PLL) circuit chip is used to process the first digital signal and the second digital signal to obtain corresponding first frequency signals and second frequency signals, and to determine a third frequency signal based on the difference between the first frequency signal and the second frequency signal; wherein the frequency difference between the first frequency signal and the second frequency signal is no greater than one-tenth of the first frequency signal. The controller is configured to determine the phase difference between the reference frequency signal and the measurement frequency signal corresponding to the first frequency signal and the third frequency signal, respectively, to obtain a first phase difference and a second phase difference; and to determine the measurement distance data corresponding to the first phase difference and the second phase difference according to a preset correspondence.

7. The phase ranging device according to claim 6, characterized in that, The mixer includes: A mixing unit is used to mix the modulation frequency signal and the local oscillator frequency signal of the first laser ruler and the second laser ruler respectively to obtain a first mixed signal of the first laser ruler and a second mixed signal of the second laser ruler. The filtering unit is used to filter the first mixing signal and the second mixing signal using a low-pass filter and a transimpedance amplifier, respectively, to extract the difference frequency signal in the first mixing signal and the difference frequency signal in the second mixing signal, so as to obtain the first difference frequency signal of the first laser ruler and the second difference frequency signal of the second laser ruler.

8. The phase ranging device according to claim 7, characterized in that, Also includes: A bandpass filter amplifier is used to amplify the first difference frequency signal and the second difference frequency signal.

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