A distance measurement method, system and computer readable storage medium

Abstract

The present application is applicable to the field of time-of-flight technology, and provides a distance measurement system, method, and computer-readable storage medium. The embodiment of the present application controls the transmitter to transmit pulse beams of n frequencies to the object to be measured; controls the collector to collect photons in the pulse beams of n frequencies reflected by the object to be measured and outputs multiple photon signals; calculates n initial flight times corresponding to the n frequencies one by one according to the multiple photon signals, constructs a virtual frequency according to the n frequencies, and calculates the measured flight time in combination with the n initial flight times; wherein n is an integer greater than or equal to 2. The ranging accuracy is effectively improved, and the generation of random errors is reduced; and the ranging range can be increased, and the flight time of the object to be measured outside the maximum ranging range can be calculated.

Description

Technical Field

[0001] The present application relates to the technical field of time of flight (TOF), and in particular to a distance measurement method and device. Background Art

[0002] The time-of-flight technology can be used to measure the distance of the object to be measured, and based on the distance of the object to be measured, a depth image containing the depth value of the object to be measured can be further obtained. Distance measurement systems based on time-of-flight technology have been widely used in consumer electronics, unmanned vehicles, virtual reality, augmented reality and other fields. The distance measurement system usually includes a transmitter and a collector. The transmitter emits a pulse beam to illuminate the object to be measured and the collector receives the pulse beam reflected by the object to be measured. The distance between the object to be measured and the distance measurement system is calculated by calculating the time from the pulse beam being emitted to being received.

[0003] At present, the distance measurement method of emitting multi-frequency pulse light beams is widely used. Although this method increases the ranging range compared to the ranging method of emitting single-frequency pulse light beams, it is easy to produce random errors when the multi-frequency pulse light beams are acquired by the collector. Even if corresponding algorithms are designed for different error conditions, it is very easy to cause calculation errors due to incorrect algorithm selection and other situations; in addition, when the object to be measured is outside the maximum ranging range, but the collector still acquires the reflected pulse light beam, it will also cause interference and lead to large distance measurement errors. Summary of the invention

[0004] In view of this, an embodiment of the present application provides a profile processing control method, a terminal device and a storage medium to solve the problem of poor stability of the profile processing production line.

[0005] A first aspect of an embodiment of the present application provides a distance measurement method, including:

[0006] Control the transmitter to emit pulse light beams of n frequencies to the object to be tested;

[0007] Controlling the collector to collect photons in the pulse light beams of n frequencies reflected by the object to be tested and outputting a plurality of photon signals;

[0008] Calculate n initial flight times corresponding to the n frequencies one by one according to the multiple photon signals;

[0009] Constructing a virtual frequency according to the n frequencies, and calculating a measured flight time in combination with the n initial flight times;

[0010] Wherein, n is an integer greater than or equal to 2.

[0011] A second aspect of the embodiments of the present application provides a distance measurement system, including a transmitter, a collector, and a processing circuit connected to the transmitter and the collector;

[0012] The transmitter is used to transmit pulse light beams of n frequencies to the object to be tested;

[0013] The collector is used to collect photons in the pulse light beams of n frequencies reflected by the object to be tested and output multiple photon signals;

[0014] The processing circuit is used to execute the steps of the distance measurement method provided in the first aspect of the embodiment of the present application.

[0015] A third aspect of an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the distance measurement method provided in the first aspect of the embodiment of the present application are implemented.

[0016] The first aspect of the embodiments of the present application provides a distance measurement method, which controls a transmitter to transmit a pulse light beam of n frequencies to an object to be measured; controls a collector to collect photons in the pulse light beam of n frequencies reflected by the object to be measured and outputs a plurality of photon signals; calculates n initial flight times corresponding to the n frequencies one by one according to the plurality of photon signals; calculates and measures the flight time according to the n frequencies and the n initial flight times, thereby effectively improving the ranging accuracy and reducing the generation of random errors; and can also increase the ranging range, and can calculate the flight time of an object to be measured that is outside the maximum ranging range.

[0017] It can be understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 is a schematic diagram of the structure of a distance measurement system provided in an embodiment of the present application;

[0020] Figure 2 This is a schematic diagram of a first flow chart of a distance measurement method provided in an embodiment of the present application;

[0021] Figure 3 This is a second flow chart of the distance measurement method provided in the embodiment of the present application;

[0022] Figure 4 This is a third flow chart of the distance measurement method provided in the embodiment of the present application;

[0023] Figure 5 This is a fourth flow chart of the distance measurement method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0024] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0025] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0026] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0027] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0028] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0029] The embodiment of the present application provides a distance measurement method, which can be applied to terminal devices including processing circuits, such as mobile phones, tablet computers, wearable devices, laptop computers, ultra-mobile personal computers (UMPCs), netbooks, and personal digital assistants (PDAs). Specifically, the method can be executed when the processing circuit of the terminal device runs a computer program with corresponding functions to control a transmitter, a collector, etc. to realize a distance measurement function. The specific type of the terminal device in the embodiment of the present application is not limited in any way.

[0030] like Figure 1 As shown, an embodiment of the present application provides a distance measurement system 100, including a transmitter 1, a collector 2, and a processing circuit 3 connected to the transmitter 1 and the collector 2;

[0031] The transmitter 1 is used to transmit a pulse light beam 300 of n frequencies to the object to be tested 200;

[0032] A collector 2, used for collecting photons in the pulse light beam 300 of n frequencies reflected by the object to be tested 200 and outputting a plurality of photon signals;

[0033] The processing circuit 3 is used to calculate n initial flight times corresponding to the n frequencies one by one according to the multiple photon signals; it is also used to calculate the measured flight time according to the n frequencies and the n initial flight times; it is also used to calculate the calibrated flight time according to the n frequencies, the n initial flight times corresponding to the n frequencies one by one and the measured flight time; wherein n is an integer greater than or equal to 2.

[0034] In application, the object to be measured can be any object in free space. At least part of the pulse beams of n frequencies emitted by the transmitter to the object to be measured is reflected back to the collector by the object to be measured. The collector collects the pulse beams of n frequencies reflected by the object to be measured and performs photoelectric conversion to obtain corresponding multiple photon signals, and then outputs the multiple photon signals to the processing circuit. The processing circuit calculates n initial flight times corresponding to the n frequencies one by one according to the multiple photon signals output by the collector, and then calculates the measured flight time according to the n frequencies and the n initial flight times. The distance between the object to be measured and the distance measurement system can be calculated based on the measured flight time. The processing circuit is used to synchronously send a trigger signal to the transmitter and the collector to synchronously trigger the transmitter to emit a pulse beam and the collector to collect the multiple light spots formed on the surface of the pixel unit after the pulse beam reflected by the object to be measured is diffracted by the grating. The trigger signal can be a clock signal.

[0035] In application, the transmitter includes a light source unit, and the light source unit includes at least one light source, each of which can be used to emit a pulsed light beam of at least one frequency. The light source can be a light emitting diode (LED), a laser diode (LD), an edge emitting laser (EEL), a vertical cavity surface emitting laser (VCSEL), etc. The number of light sources included in the light source unit can be set according to actual needs, and the light source unit can be a one-dimensional or two-dimensional light source array composed of at least two light sources. The light source array can be a vertical cavity surface emitting laser array chip formed by generating multiple vertical cavity surface emitting lasers on a single semiconductor substrate, and the arrangement of the light sources in the light source array can be regular or irregular. The pulsed light beam emitted by the light source can be visible light, infrared light, ultraviolet light, etc.

[0036] In one embodiment, the transmitter further includes a driver for controlling the light source unit to emit pulse light beams of preset n frequencies, the preset n frequencies are set according to the ranging range of the distance measurement system, and the driver is connected to the light source unit.

[0037] In the application, the light source unit emits a pulse light beam to the object to be measured under the control of the driver. It is understandable that a part of the processing circuit or other circuits independent of the processing circuit can also be used to control the light source unit to emit a pulse light beam. The preset n frequencies are negatively correlated with the distance measurement range of the distance measurement system, and the preset pulse period is positively correlated with the distance measurement range of the distance measurement system.

[0038] In one embodiment, the transmitter further includes a transmitting optical element for optically modulating the pulse light beam emitted by the light source unit and then projecting the pulse light beam to the object to be measured.

[0039] In applications, optical modulation may be diffraction, refraction, reflection, etc., and the modulated pulsed light beam may be a focused light beam, a flood light beam, a structured light beam, etc. The emitting optical element may include at least one of a lens, a liquid crystal element, a diffractive optical element, a microlens array, a metasurface optical element, a mask, a reflector, a micro-electro-mechanical system (MEMS) galvanometer, etc.

[0040] Figure 1 The transmitter 1 is exemplarily shown to include a light source unit 11 , a transmitting optical element 12 and a driver 13 , and the light source unit 11 is connected to the driver 13 .

[0041] In the application, the collector includes a pixel unit, which can be a pixel array composed of multiple photosensitive pixels, and the photosensitive pixel can be one of the single-photon devices for collecting photons, such as avalanche photon diode (APD), single-photon avalanche photodiode (SPAD), and multi-pixel photoncounter (Silicon photomultiplier, SiPM). The single-photon avalanche photodiode can respond to the incident single photon and output a signal indicating the time when the photon arrives at the single-photon avalanche photodiode, and use methods such as time-correlated single photon counting (TCSPC) to realize the collection of weak light signals and the calculation of flight time. In one embodiment, the collector also includes a receiving optical element for focusing the pulse light beam reflected by the object to be measured onto the pixel unit.

[0042] In one embodiment, the receiving optical element further includes a filtering unit for filtering out background light and stray light incident on all pixels. The filtering unit may be a low-pass filter.

[0043] Figure 1 The collector 2 is shown as an example in FIG. 2 including a pixel unit 21, a filter unit 22 and a receiving optical element 23. It should be understood that Figure 1 In the figure, the filter unit 22 is arranged between the pixel unit 21 and the receiving optical element 23 for the sake of convenience of illustration, and is not used to limit the relative positions of the filter unit 22 and the receiving optical element 23 in actual applications.

[0044] In the application, the processing circuit includes a time to digital converter (TDC) circuit and a histogram circuit connected to the pixel unit, and may also include a signal amplifier, an analog-to-digital converter (ADC) and other devices. These devices can be integrated with the pixel unit or used as part of the processing circuit. The TDC circuit is used to calculate the initial flight time of the pulse beam and convert the initial flight time into a time code output based on the reception time of the received photon signal and the emission time of the pulse beam emitted by the transmitter to the target, address the corresponding time bin (time interval) in the histogram circuit according to the time code, and add 1 to the photon count value within the time interval. After a large number of repeated pulse detections, a statistical histogram of photon counts can be obtained by statistics, and the time corresponding to the peak position of the histogram is determined to be the measured flight time, wherein the time code can be a temperature code or a binary code. The processing circuit may be a central processing unit (CPU), or other general-purpose processors, system-on-a-chip (SOC), digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware arrays, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0045] In one embodiment, the distance measurement system further comprises a memory for storing a pulse coding program. A driver is connected to the memory for controlling the time and frequency of the light source unit emitting the pulse light beam by using the pulse coding program.

[0046] In one embodiment, the distance measurement system may further include at least one of an RGB camera, an infrared camera, and an inertial measurement unit (IMU) for realizing functions such as 3D texture modeling, infrared face recognition, and simultaneous localization and mapping (SLAM).

[0047] like Figure 2 As shown, the distance measurement method provided in the embodiment of the present application includes the following steps S201 to S204 implemented by the processing circuit in the above embodiment:

[0048] Step S201, controlling the transmitter to transmit pulse light beams of n frequencies to the object to be tested; wherein n is an integer greater than or equal to 2.

[0049] In the application, the magnitudes of the n frequencies need to be close to each other to ensure the accuracy of distance measurement. The larger the frequency of the pulse beam, the higher the frequency of the pulse beam emitted by the transmitter, the frequency of the pulse beam collected by the collector, the sensitivity of the distance measurement system and the ranging accuracy. The frequency of the pulse beam can be set according to actual needs. In one embodiment, the frequencies of the pulse beams emitted by the transmitter are f1, f2, f3…f n , wherein the first frequency f1 has the smallest value, and the following frequencies increase in sequence. In one embodiment, the transmitter is controlled to transmit two pulse light beams with frequencies f1 and f2 to the object to be tested. Preferably, the pulse light beams with two frequencies can be selected to be transmitted alternately.

[0050] Step S202: Control the collector to collect photons in the pulse light beams of n frequencies reflected by the object to be tested and output a plurality of photon signals.

[0051] In the application, at least part of the pulse beams of n frequencies emitted by the transmitter to the object to be tested is reflected back to the collector by the object to be tested, so that the collector can identify and collect the pulse beams of corresponding frequencies reflected by the object to be tested and perform photoelectric conversion to obtain corresponding photon signals, and then output the photon signals to the processing circuit. The processing circuit synchronously sends a trigger signal to the transmitter and the collector to synchronously trigger the transmitter to emit the pulse beam of the corresponding frequency and the collector to collect the pulse beam reflected by the object to be tested. The trigger signal can be a clock signal, and the clock signal used to trigger the transmitter to emit the pulse beam of n frequencies to the object to be tested can be defined as a starting clock signal.

[0052] Step S203: Calculate, according to the multiple photon signals, n initial flight times corresponding to the n frequencies one by one.

[0053] In the application, the initial flight time indicates the flight time of the pulse light beam in the current cycle when the pulse light beam is collected by the collector. When the processing circuit controls the transmitter to transmit pulse light beams of n frequencies to the object to be tested, the processing circuit will calculate n initial flight times corresponding to the n frequencies one by one according to multiple photon signals, and can perform maximum value peak search according to the histogram to obtain n initial flight times, for example, the n flight times corresponding to the n peaks with the largest number of photon signals in the histogram are obtained as the initial flight time. The embodiment of the present application does not impose any restrictions on the method of obtaining the initial flight time.

[0054] Step S204: construct a virtual frequency according to the n frequencies, and calculate the measured flight time in combination with the n initial flight times.

[0055] In application, the maximum detection distance of the system can be extended by emitting pulse beams of n frequencies. Since there are some cases where the measured flight time exceeds the number of cycles corresponding to its frequency, it is assumed that the first frequency is the minimum frequency and the second frequency begins to gradually increase. When the flight time of the object to be measured is greater than the period corresponding to the first frequency, the flight time measured at the period corresponding to each frequency is different. We define the flight time calculated at each frequency as the initial flight time. If the measured flight time exceeds the number of cycles corresponding to a certain frequency by m, the measured flight time is actually the sum of the m periods corresponding to the frequency and the initial flight time. In the present invention, a new virtual frequency is constructed according to the n frequencies emitted, and the virtual frequency is less than any one of the n frequencies, so that the measured flight time does not exceed the period corresponding to the virtual frequency, and the measured flight time is calculated in combination with the calculated initial flight time.

[0056] Since the constructed virtual frequency is small, the sensitivity and ranging accuracy of the distance measurement system are not high, resulting in possible errors in the calculated measured flight time. Therefore, the distance measurement method of the present application also includes the following steps:

[0057] Step S205: Calculate the calibration flight time according to the n frequencies, the n initial flight times corresponding to the n frequencies one by one, and the measured flight times.

[0058] In the application, by selecting the ith frequency among the n frequencies, the ith initial flight time corresponding to the ith frequency and the measured flight time, the number of cycles m of the ith initial flight time is calculated, and then the sum of the time of the initial flight time through the corresponding m complete cycles and the initial flight time is calculated as the calibration flight time t. Since the frequency value of the ith frequency is much larger than the frequency value of the measured flight time, a more accurate calibration flight time than the measured flight time can be calculated, thereby improving the accuracy of distance measurement. It can be understood that the ith frequency can be any one of the n frequencies.

[0059] Furthermore, the distance between the distance measurement system and the object to be measured can be calculated based on the calibrated flight time, and the calculation formula is as follows:

[0060]

[0061] Where D is the distance between the object to be measured and the distance measurement system, c is the speed of light, and t is the calibration flight time.

[0062] like Figure 3 As shown, in one embodiment, step S204 includes the following steps S301 to S303:

[0063] Step S301, obtaining the phase of the i-th initial flight time according to the i-th frequency and the i-th initial flight time corresponding to the i-th frequency; wherein i=1, 2, ..., n.

[0064] In one embodiment, the calculation formula for calculating the phase of the i-th initial flight time in step S301 is:

[0065]

[0066] in, represents the phase of the ith initial flight time, f i represents the i-th frequency, t i represents the i-th initial flight time corresponding to the i-th frequency.

[0067] In the application, the trigonometric function that characterizes the phase of the i-th initial flight time is:

[0068] sin(2πf i t i );

[0069] cos(2πf i t i );

[0070] Since the measured flight time satisfies the relation The calculation formula for the phase of the measured flight time corresponding to the i-th frequency can be obtained as follows:

[0071]

[0072] in, represents the phase of the measured flight time, f i represents the i-th frequency, Indicates the measured flight time, m i It represents the i-th cycle number, that is, the multiple of the measured flight time exceeding the cycle corresponding to the i-th frequency.

[0073] Furthermore, from formula (1), it can be obtained that the phase between the measured flight time and the i-th initial flight time satisfies the following relationship:

[0074]

[0075]

[0076] In one embodiment, the transmitter is controlled to transmit two pulse beams with frequencies f1 and f2 to the object to be tested, and the initial flight times are t1 and t2 respectively. The calculation formula for calculating the phase of the initial flight time in step S301 is:

[0077]

[0078]

[0079] in, represents the phase corresponding to the first initial flight time t1, Represents the phase corresponding to the second initial flight time t2.

[0080] In the application, the transmitter is controlled to emit a pulse beam with a frequency of f1 to the object to be measured, and the corresponding initial flight time is t1. The phase of the measured flight time and the phase of the first initial flight time satisfy the following relationship:

[0081]

[0082]

[0083] The transmitter is controlled to emit a pulse beam with a frequency of f2 to the object under test, and the corresponding initial flight time is t2. The phase of the measured flight time and the phase of the second initial flight time satisfy the following relationship:

[0084]

[0085]

[0086] The derivation process of the above relationship and the above embodiments and The derivation process is the same as that of , which will not be repeated here.

[0087] Step S302: Select two frequencies according to the n frequencies to construct a first virtual frequency.

[0088] In one embodiment, the calculation formula for selecting two frequencies from n frequencies to construct the first virtual frequency in step S302 is:

[0089] f′ k =|f i -f j |, k=1,2,…,n(n-1) / 2, j=1,2,…,n, i≠j;

[0090] f = min(f′ k );

[0091] Among them, f′ k represents the absolute value of the difference between the i-th frequency and the j-th frequency, f represents the first virtual frequency, min(f′ k ) means taking the minimum value among the absolute values ​​of the difference between any two different frequencies among n frequencies.

[0092] In an application, the processing circuit may subtract two of the n frequencies from each other to obtain a total of n(n-1) / 2 absolute values ​​of the differences between the ith frequency and the jth frequency, and obtain the minimum value therebetween as the first virtual frequency.

[0093] In the application, the i-th frequency and the j-th frequency among the n frequencies satisfy the relationship:

[0094]

[0095] Among them, min(f i , f j ) represents the minimum value between the i-th frequency and the j-th frequency, |f i -f j | represents the absolute value of the difference between the i-th frequency and the j-th frequency;

[0096] As the frequency of the pulse beam emitted by the transmitter, the frequency of the pulse beam collected by the collector, the sensitivity and ranging accuracy of the distance measurement system are higher, and the difference between the i-th frequency and the j-th frequency is smaller, the first virtual frequency constructed by the i-th frequency and the j-th frequency is smaller, Where, f represents the first virtual frequency, D max Representing the maximum ranging range of the distance measurement system, it can be obtained that the smaller the first virtual frequency, the larger the maximum ranging range of the distance measurement system. Therefore, the above relationship can be used to set sufficiently large i-th frequency and j-th frequency to increase the maximum ranging range of the distance measurement system. It should be noted that limiting the absolute value of the difference between the i-th frequency and the j-th frequency to be less than one-fifth of the minimum value of the i-th frequency and the j-th frequency is only exemplary and can be limited to one-third, one-seventh, one-tenth, etc. according to actual needs. The embodiment of the present application does not impose any limitation on the size relationship between the i-th frequency and the j-th frequency.

[0097] For example, the transmitter is controlled to emit three pulse beams of frequencies f1, f2 and f3 to the object under test. The magnitude of the first frequency is f1 = 50 Hz, the magnitude of the second frequency is f2 = 49 Hz, and the magnitude of the third frequency is f3 = 47 Hz. The calculation formula for selecting two frequencies from n frequencies to construct the first virtual frequency is:

[0098] f′1=|f1-f2|=1Hz;

[0099] f′2=|f1-f3|=3Hz;

[0100] f′3=|f2-f3|=2Hz;

[0101] The minimum value f′1 is obtained as the first virtual frequency. It should be noted that the above calculation formula for constructing the first virtual frequency is only exemplary, and the embodiment of the present application does not impose any limitation on the construction method of the first virtual frequency.

[0102] In one embodiment, the transmitter is controlled to transmit a pulse beam with two frequencies f1 and f2 toward the target, for example, an alternating transmission scheme may be adopted. The calculation formula for selecting two frequencies from n frequencies to construct the first virtual frequency in step S302 is:

[0103] f = |f1-f2|;

[0104] Among them, f1 represents the first frequency, and f2 represents the second frequency.

[0105] In an application, when the transmitter transmits pulse light beams of two frequencies to the object to be tested, the processing circuit can obtain the absolute value of the difference between the first frequency and the second frequency as the first virtual frequency.

[0106] Step S303: Calculate the measured flight time according to the first virtual frequency and the phase of the initial flight time corresponding to the two frequencies used to construct the first virtual frequency.

[0107] In one embodiment, the calculation formula for calculating the measured flight time in step S303 is:

[0108]

[0109]

[0110] Assume that the first virtual frequency f=f i -f j ,but

[0111] in, represents the phase of the first initial flight time corresponding to the first frequency used to construct the first virtual frequency, The phase of the second initial flight time corresponding to another frequency used to construct the first virtual frequency.

[0112] In the application, since the frequency value of the first virtual frequency is much smaller than the frequency value of the i-th frequency, the period length of the pulse beam of the first virtual frequency is much larger than the period length of the pulse beam of the i-th frequency, so that the pulse beam of each frequency can be emitted by the transmitter, reflected by the object to be measured and collected by the collector within the period corresponding to the first virtual frequency, that is, the period number of the measured flight time is 0, and the measured flight time calculated by the calculation formula for calculating the measured flight time is in, It indicates that the measured flight time exceeds the multiple of the period corresponding to the first virtual frequency f, which is recorded as the number of periods. represents the initial flight time corresponding to the first virtual frequency, and takes The flight time can be measured Since trigonometric functions are periodic, the calculation formula The two measured flight times can be calculated; the calculation formula is Two measured flight times may also be calculated. The present application can overcome the periodicity of trigonometric functions by combining the above two calculation formulas to obtain the actual measured flight time.

[0113] In one embodiment, the transmitter is controlled to transmit two pulse light beams with frequencies f1 and f2 to the object to be measured, and the corresponding initial flight times are t1 and t2 respectively. The calculation formula for calculating the measured flight time in step S303 is:

[0114]

[0115]

[0116]

[0117]

[0118] in, represents the phase corresponding to the first initial flight time t1, Represents the phase corresponding to the second initial flight time t2.

[0119] In application, when the transmitter is controlled to transmit two pulse light beams with frequencies f1 and f2 to the object to be measured, the calculation process of the calculation formula for measuring the flight time is consistent with the calculation process in the aforementioned embodiment, which will not be repeated here.

[0120] In applications, the frequency value of the first virtual frequency is much smaller than the frequency value of the i-th frequency, so the period length corresponding to the first virtual frequency is much larger than the period length corresponding to the i-th frequency. It can be obtained that the ranging range of the pulse light beam emitting the first virtual frequency is much larger than the ranging range of the pulse light beam of the i-th frequency, which effectively solves the distance aliasing problem caused by the detected object being outside the ranging range corresponding to the minimum frequency.

[0121] like Figure 4 As shown, in one embodiment, step S205 includes steps S401 to S402:

[0122] Step S401, calculating the i-th cycle number according to the i-th frequency, the i-th initial flight time corresponding to the i-th frequency and the measured flight time; the i-th cycle number is a multiple of the measured flight time exceeding the cycle corresponding to the i-th frequency.

[0123] In one embodiment, the calculation formula for calculating the i-th cycle number in step S401 is:

[0124]

[0125] Among them, m i represents the i-th cycle number, Denotes the measured flight time, t i represents the i-th initial flight time corresponding to the i-th frequency, f i represents the i-th frequency.

[0126] In the application, since the frequency value of the first virtual frequency is much smaller than the frequency value of the i-th frequency, the accuracy of the measured flight time corresponding to the first virtual frequency is not high, and there may be errors that result in the inability to accurately calculate the flight time of the object to be measured. Therefore, the number of cycles that the measured flight time exceeds the corresponding cycle of the i-th frequency is calculated based on the calculated measured flight time and the initial flight time of the i-th frequency. The calculated number of cycles can be rounded off, and step S402 is further performed based on the number of cycles and the corresponding initial flight time to calculate the accurate measured flight time, that is, the calibrated flight time. It can be understood that any one of the n frequencies and the initial flight time corresponding to the frequency can be selected to calculate the number of cycles of the target time in the cycle corresponding to the frequency.

[0127] In one embodiment, the transmitter is controlled to transmit two pulse beams with frequencies f1 and f2 to the object to be tested, and the corresponding initial flight times are t1 and t2, respectively. The calculation formula for calculating the number of cycles of the i-th initial flight time in step S401 is:

[0128] or,

[0129] Wherein, m1 represents the multiple of the measured flight time exceeding the period corresponding to the first frequency f1, recorded as the first period number, represents the measured flight time, and m2 represents the multiple of the measured flight time exceeding the period corresponding to the second frequency f2, which is recorded as the second period number.

[0130] In the application, the processing method of the first cycle number and the second cycle number is consistent with the processing method of the above embodiment, which will not be repeated here. It can be understood that in the actual calculation process, only one cycle number needs to be calculated to calculate the calibration flight time of the corresponding frequency.

[0131] Step S402: Calculate the calibration flight time according to the i-th frequency, the i-th initial flight time corresponding to the i-th frequency, and the i-th number of cycles.

[0132] In one embodiment, the calculation formula for the calibration flight time calculated in step S402 is:

[0133]

[0134] Where t is the calibration flight time, t i represents the i-th initial flight time corresponding to the i-th frequency, round(m i ) represents the number of the i-th rounded period, f i represents the i-th frequency.

[0135] In the application, since the frequency value of the i-th frequency is much greater than the first virtual frequency, the accuracy of the calculated calibration flight time is more accurate than the measured flight time. It can be understood that the i-th frequency used to calculate the calibration flight time is any frequency among the n frequencies, not necessarily the two frequencies that construct the first virtual frequency. No matter which frequency is selected, the accurate flight time of the object under test can be obtained in the end.

[0136] In one embodiment, n=2, the calibration flight time calculated in step S402 may be calculated by selecting the flight time corresponding to the frequency f1 or the flight time corresponding to the frequency f2, and the specific calculation formula is:

[0137] or,

[0138] Wherein, round(m1) represents the first rounded period number, and round(m2) represents the second rounded period number.

[0139] In applications, since the frequency values ​​of the first frequency and the second frequency are much greater than the first virtual frequency, the accuracy of the calculated calibration flight time is more accurate than the measured flight time.

[0140] In the application, the number of cycles that the measured flight time exceeds the cycle corresponding to the i-th frequency is calculated based on the n frequencies emitted by the transmitter, the i-th frequency, the i-th initial flight time corresponding to the i-th frequency, and the measured flight time, and the calibration flight time is further calculated in combination with the i-th initial flight time. Since the frequency value of the i-th frequency is much larger than the frequency value of the measured flight time, a more accurate calibration flight time than the measured flight time can be calculated, thereby improving the accuracy of distance measurement.

[0141] like Figure 5As shown, in another embodiment, steps S501 to S504 are included after step S303:

[0142] Step S501: Select two frequencies according to the n frequencies to construct a second virtual frequency.

[0143] In one embodiment, the calculation formula for selecting two frequencies from n frequencies to construct the second virtual frequency in step S501 is:

[0144] f″ k =f i +f j , k=1,2,…,n(n-1) / 2, j=1,2,…,n, i≠j;

[0145] f′=max(f″ k );

[0146] Among them, f″ k represents the sum of the i-th frequency and the j-th frequency, f′ represents the second virtual frequency, max(f″ k ) means taking the maximum value of the sum of any two different frequencies among n frequencies.

[0147] In the application, the processing circuit can add n frequencies in pairs to obtain a total of n(n-1) / 2 sums of the ith frequency and the jth frequency, and obtain the maximum value as the second virtual frequency. Since the higher the frequency of the pulse light beam emitted by the transmitter and the frequency of the pulse light beam collected by the collector, the higher the sensitivity and ranging accuracy of the distance measurement system, therefore, by setting a sufficiently large second virtual frequency, the sensitivity and ranging accuracy of the distance measurement system can be increased.

[0148] For example, the transmitter is controlled to emit pulse beams with three frequencies f1, f2 and f3 toward the target. The magnitude of the first frequency is f1 = 50 Hz, the magnitude of the second frequency is f2 = 49 Hz, and the magnitude of the third frequency is f3 = 47 Hz. The calculation formula for constructing the second virtual frequency based on n frequencies is:

[0149] f″1=f1+f2=99Hz;

[0150] f″2=f1+f3=97Hz;

[0151] f″3=f2+f3=96Hz;

[0152] The maximum value f″1 is obtained as the first virtual frequency. It should be noted that the above calculation formula for constructing the second virtual frequency is only exemplary, and the embodiment of the present application does not impose any limitation on the construction method of the second virtual frequency.

[0153] In one embodiment, the transmitter is controlled to transmit pulsed light beams with two frequencies f1 and f2 toward the target, for example, an alternating transmission scheme may be adopted. The calculation formula for selecting two frequencies from n frequencies to construct the second virtual frequency in step S501 is:

[0154] f′=f1+f2;

[0155] Wherein, f′ represents the second virtual frequency, f1 represents the first frequency, and f2 represents the second frequency.

[0156] In an application, when the transmitter transmits pulse light beams of two frequencies to the object to be tested, the processing circuit can obtain the sum of the first frequency and the second frequency as the second virtual frequency.

[0157] Step S502: Calculate the initial flight time corresponding to the second virtual frequency according to the second virtual frequency and the phase used to construct the initial flight time corresponding to the second virtual frequency.

[0158] In one embodiment, the calculation formula for calculating the initial flight time corresponding to the second virtual frequency in step S502 is:

[0159]

[0160]

[0161] Assume that the second virtual frequency f′=f i +f j ,but

[0162] in, represents the initial flight time corresponding to the second virtual frequency, represents the phase of the third initial flight time corresponding to the first frequency used to construct the second virtual frequency, The phase of a fourth initial flight time corresponding to another frequency used to construct the second virtual frequency.

[0163] In the application, it is necessary to calculate the sum of the time of m complete cycles of the initial flight time corresponding to the second virtual frequency and the initial flight time corresponding to the second virtual frequency as the calibration flight time. The measured flight time satisfies the following relationship: It means that the measured flight time exceeds the multiple of the period corresponding to the second virtual frequency f′. When the number of periods is equal to 0, that is, The initial flight time corresponding to the second virtual frequency can be obtained Since trigonometric functions are periodic, the calculation formula The initial flight time corresponding to the two second virtual frequencies can be calculated; according to the calculation formula The initial flight times corresponding to the two second virtual frequencies may also be calculated. The present application can overcome the periodicity of the trigonometric function by combining the above two calculation formulas to obtain the actual initial flight time of the second virtual frequency.

[0164] Step S503: Calculate a multiple of the measured flight time exceeding a period corresponding to the second virtual frequency according to the second virtual frequency, the initial flight time of the second virtual frequency and the measured flight time.

[0165] In one embodiment, the calculation formula for calculating the multiple of the measured flight time exceeding the period corresponding to the second virtual frequency in step S503 is:

[0166]

[0167] In the application, the processing method for the measured flight time exceeding the multiple of the period corresponding to the second virtual frequency is consistent with the processing method for the period number of the i-th initial flight time in the above step S401, which will not be repeated here.

[0168] Step S504: Calculate a calibrated flight time according to the second virtual frequency, the initial flight time of the second virtual frequency, and a multiple of the measured flight time exceeding a period corresponding to the second virtual frequency.

[0169] In one embodiment, the calculation formula for calculating the calibration flight time in step S504 is:

[0170]

[0171] in, It indicates that the measured flight time exceeds the integer multiple of the period corresponding to the second virtual frequency.

[0172] In applications, since the frequency value of the second virtual frequency is greater than the frequency value of the i-th frequency, a more accurate calibration flight time can be calculated.

[0173] In the application, a second virtual frequency is constructed according to the n frequencies sent by the reflector; the initial flight time corresponding to the second virtual frequency is calculated according to the phase of the initial flight time corresponding to the second virtual frequency and the two frequencies used to construct the second virtual frequency, and the flight time is further calculated and calibrated in combination with the measured flight time exceeding the integer multiple of the period corresponding to the second virtual frequency. Since the frequency value of the second virtual frequency is much larger than the frequency value of the i-th frequency, compared with the calibrated flight time calculated according to the i-th frequency, the i-th initial flight time and the i-th period number, this embodiment can calculate a more accurate calibrated flight time, thereby further improving the accuracy of distance measurement.

[0174] The distance measurement method provided in the embodiment of the present application controls the transmitter to emit pulse beams of n frequencies to the object to be measured; controls the collector to collect photons in the pulse beams of n frequencies reflected by the object to be measured and outputs multiple photon signals; calculates n initial flight times corresponding to the n frequencies one by one according to the multiple photon signals, constructs a virtual frequency according to the n frequencies, and calculates the measured flight time in combination with the n initial flight times; wherein n is an integer greater than or equal to 2. The ranging accuracy is effectively improved, the generation of random errors is reduced; and the ranging range can be increased, and the flight time of the object to be measured outside the maximum ranging range can be calculated.

[0175] The embodiment of the present application further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a controller, the steps in the above-mentioned distance measurement method embodiments can be implemented.

[0176] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, please refer to the relevant description of other embodiments. In the embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative.

[0177] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application 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 make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A distance measurement method, It is characterized in that include: Control the transmitter to emit pulse light beams of n frequencies to the object to be tested; Controlling the collector to collect photons in the pulse light beams of n frequencies reflected by the object to be tested and outputting a plurality of photon signals; Calculate n initial flight times corresponding to the n frequencies one by one according to the multiple photon signals; Constructing a virtual frequency according to the n frequencies, and calculating the measured flight time in combination with the n initial flight times; wherein n is an integer greater than or equal to 2; The calibration flight time is calculated according to the n frequencies, n initial flight times corresponding one by one to the n frequencies, and the measured flight time, including: selecting two frequencies according to the n frequencies to construct a second virtual frequency; calculating the initial flight time corresponding to the second virtual frequency according to the phase of the second virtual frequency and the initial flight time corresponding to the two frequencies used to construct the second virtual frequency; calculating the multiple of the measured flight time exceeding the corresponding period of the second virtual frequency according to the second virtual frequency, the initial flight time of the second virtual frequency, and the measured flight time; and calculating the calibration flight time according to the second virtual frequency, the initial flight time of the second virtual frequency, and the multiple of the measured flight time exceeding the corresponding period of the second virtual frequency.

2. The distance measurement method according to claim 1, It is characterized in that The step of constructing a virtual frequency according to the n frequencies and calculating the measured flight time in combination with the n initial flight times includes: Selecting two frequencies according to the n frequencies to construct a first virtual frequency; calculating the measured flight time according to the first virtual frequency and the phase of the initial flight time corresponding to the two frequencies used to construct the first virtual frequency; The phase of the initial flight time is calculated according to the i-th frequency and the i-th initial flight time corresponding to the i-th frequency, i=1, 2, ..., n.

3. The distance measurement method according to claim 2, It is characterized in that The calculation formula of the phase of the initial flight time is: in, represents the phase of the i-th initial flight time, f i represents the i-th frequency, t i represents the i-th initial flight time corresponding to the i-th frequency; The calculation formula for selecting two frequencies according to the n frequencies to construct the first virtual frequency is: f k ′ =|f i -f j |,k=1,2,…,n(n-1) / 2,j=1,2,…,n,i≠j; f=min(f k ′ ); Among them, f k ′ represents the absolute value of the difference between the i-th frequency and the j-th frequency, f represents the first virtual frequency, min(f k ′ ) represents taking the minimum value among the absolute values ​​of the differences between any two different frequencies among the n frequencies; The calculation formula for calculating the measured flight time according to the phase of the initial flight time corresponding to the first virtual frequency and the two frequencies used to construct the first virtual frequency is: in, represents the measured flight time, represents the phase of a first initial flight time corresponding to a frequency used to construct the first virtual frequency, The phase of a second initial flight time corresponding to another frequency used to construct the first virtual frequency.

4. The distance measurement method according to claim 1, It is characterized in that The step of calculating the calibration flight time according to the n frequencies, the n initial flight times corresponding to the n frequencies one by one, and the measured flight time comprises: Calculate the i-th cycle number according to the i-th frequency, the i-th initial flight time corresponding to the i-th frequency and the measured flight time; the i-th cycle number is a multiple of the measured flight time exceeding the cycle corresponding to the i-th frequency; The calibrated flight time is calculated according to the i-th frequency, the i-th initial flight time corresponding to the i-th frequency, and the i-th number of cycles.

5. The distance measurement method according to claim 4, It is characterized in that The calculation formula for calculating the i-th cycle number according to the i-th frequency, the i-th initial flight time corresponding to the i-th frequency and the measured flight time is: Among them, m i represents the i-th cycle number, represents the measured flight time, t i represents the i-th initial flight time corresponding to the i-th frequency, f i represents the i-th frequency; The calculation formula for calculating the calibration flight time according to the i-th frequency, the i-th initial flight time and the i-th number of cycles is: Wherein, t represents the calibration flight time, round(m i ) represents the i-th rounded period number.

6. The distance measurement method according to any one of claims 1 to 5, It is characterized in that Control the transmitter to transmit two frequencies to the object under test, namely f 1 and f 2 The pulsed light beam is used to calculate the first initial flight time and the second initial flight time corresponding to the two frequencies respectively.

7. A distance measurement system, It is characterized in that It includes a transmitter, a collector, and a processing circuit connected to the transmitter and the collector; The transmitter is used to transmit pulse light beams of n frequencies to the object to be tested; The collector is used to collect photons in the pulse light beams of n frequencies reflected by the object to be tested and output multiple photon signals; The processing circuit is used to execute the steps of the distance measurement method according to any one of claims 1 to 5.

8. A computer-readable storage medium storing a computer program. It is characterized in that When the computer program is executed by a processing circuit, the steps of the distance measurement method according to any one of claims 1 to 5 are implemented.

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