A laser radar detection system and detection device

Abstract

The application provides a laser radar detection system, characterized in that the system comprises a driving signal generation unit, a modulation sequence correction module, an array type return light receiving module and a processing module; the driving signal generation unit drives a laser source to emit a pulse type detection laser sequence through a laser modulation driving circuit; the modulation sequence correction module generates a corrected modulation sequence according to the driving signal; the array type return light receiving module receives a return light signal reflected by a detected object in a field of view and generates a return signal; and the processing module obtains a distance related signal according to the corrected modulation sequence generated by the modulation sequence correction module and the return signal according to a preset rule, and outputs distance information of the final detected object according to the distance related signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, in particular to a laser radar detection system and a detection device. BACKGROUND

[0002] Distance detection, especially active detection system realized by laser source, its principle is to actively emit the emitted light for detection by light source, such as near-infrared type detection light, whose wavelength can be selected in the range of 800-1200nm, which is not limited here, and the use of near-infrared type detection wave can also ensure the safety when there is a human object in the field of view, so the near-infrared type active detection system is more and more widely used in various scenes, such as subsequent automatic driving, intelligent door lock, security camera, mobile phone three-dimensional camera and so on.

[0003] Time-of-flight (“TOF”) light detection and ranging (“LIDAR”) is a technology used for remote distance measurement. A TOF LIDAR sensor determines the distance between an instrument including the sensor and an object by measuring the time required for a laser pulse to travel between the instrument and the object.

[0004] The currently widely used detection methods include indirect time-of-flight (ITOF) measurement scheme and direct time-of-flight (DTOF) measurement scheme. Most of the indirect time-of-flight measurement schemes use a phase offset measurement method, that is, the phase difference between the transmitted wave and the received wave. The horizontal coordinate of the transmitted and received waves is time t, and the vertical coordinate is light intensity. According to the phase difference between the two, the time of flight t can be obtained, and the distance of the detected object can be calculated according to d=ct / 2. The direct time-of-flight measurement scheme generally uses a picosecond-level resolution measurement system (mostly SPAD+TDC) to directly obtain the time difference between the transmission and the corresponding receiving end trigger, that is, the time of flight t, and then calculate the distance of the detected object. Of course, there is another type called coherent detection. The coherent laser signal and the local laser oscillation signal are incident on the detector photosensitive surface under the condition of satisfying the wavefront matching (that is, maintaining the same phase relationship on the entire photosensitive surface of the laser detector), generating beat frequency or coherent superposition. The size of the output electrical signal of the detector is proportional to the square of the sum of the to-be-measured laser signal wave and the local laser oscillation wave. Of course, the above detection method has its own advantages, but it still has great deficiencies in pixel level, fast processing and efficient use of transmission energy.

[0005] In recent years, some direct time-of-flight detection (non-coherent) laser radar principles have also been developed, gradually becoming a detection technology that more people understand. The prior art 1: patent application number CN202010604232.3, named a new type of laser ranging method and laser radar system, proposes a new type of detection mechanism, which does not use coherent light principles in the optical path, but performs correlation operations in the electrical signal stage. Further, the distance or other information of the detected object is obtained through the correlation operation of the electrical signal. However, in fact, this method still has the following limitations (1) According to the non-coherent chirp signal amplitude modulation continuous wave laser three-dimensional imaging principle, the difference frequency signal is generated by multiplying the delayed chirp signal and the local signal. From the energy utilization point of view, since the gain of the detector needs to be modulated at a high speed, the detection efficiency of the prior art is low, and the ranging range is small; (2) The prior art uses a wideband amplifier, a mixer, and an A / D device. The dynamic range of these devices limits the dynamic range of the received laser signal, thereby limiting the dynamic receiving range of the prior art; (3) The performance of the laser three-dimensional imaging system realized by the prior art is greatly affected by the chirp signal frequency modulation linearity and frequency modulation flatness.

[0006] The prior art 2: patent application number 202111112299.6, named a laser radar detection system, relative to the above prior art, adds a counting sequence generation module, which converts the photon counting sequence or the accumulated photon counting sequence into an adaptive photon counting sequence or an adaptive accumulated photon counting sequence, respectively, and generates an accumulated counting sequence after processing by a digital multiplier and a preset rule operation module. Similarly, by analyzing the frequency spectrum characteristics of the accumulated counting sequence, the target information can be solved.

[0007] The prior art 3: patent application number 202210132268.5, named a laser radar detection system and a detection method, relative to the above prior art, adds a counting sequence splicing module, which obtains a copied splicing signal according to the return signal. Through such design, smaller laser emission energy can be used to achieve smaller ranging deviation.

[0008] The above prior art uses the collected mixing signal to solve the distance, and the mixing signal in the signal collection interval time is not effectively utilized. The shorter the integration time and the lower the sampling rate, the lower the utilization rate.

[0009] The continuous laser signal is changed into a laser pulse sequence, so that the energy thereof can be fully utilized within the integration time. Although this method improves the energy utilization, in practical applications, in order to simplify the laser emission system, it is required that the single pulse energy in the emitted laser pulse sequence be the same, which requires that the pulse repetition frequency fs, the frequency-modulated continuous wave bandwidth B, the period T and the initial sweep frequency f0 satisfy specific constraint conditions, which limits the flexibility of parameter configuration of the above ranging method or detection system.

[0010] The above prior art is an improvement on the non-coherent chirp signal amplitude-modulated continuous wave laser three-dimensional imaging, so that the emitted laser energy can be fully utilized, and is a full-digital architecture, thereby improving the energy utilization efficiency and simplifying the system structure, so that the constraint conditions can be broken by further optimizing the digital architecture, and the parameter flexibility in different applications can be realized. SUMMARY

[0011] The present application aims at the deficiencies in the prior art, and in order to achieve the above object, the technical solutions adopted by the embodiments of the present application are as follows:

[0012] In a first aspect, the embodiments of the present application provide a laser radar detection system, characterized in that it comprises a driving signal generation unit, a modulation sequence correction module, an array type return light receiving module and a processing module.

[0013] Optionally, the laser radar detection system further comprises a digital multiplier, the modified modulation sequence and the return signal are multiplied in the digital multiplier, and then a distance-related signal is obtained by operation according to a preset rule, and the processing module outputs the distance information of the final detected object according to the distance-related signal.

[0014] Optionally, the laser radar detection system further comprises a counting sequence splicing module, the modified modulation sequence and the signal output by the counting sequence splicing module are multiplied in the digital multiplier, and then a distance-related signal is obtained by operation according to a preset rule, and the processing module outputs the distance information of the final detected object according to the distance-related signal.

[0015] Optionally, the laser radar detection system further comprises a count sequence generation module, the modified modulation sequence is obtained according to a preset rule after the modified modulation sequence and a signal output by the count sequence generation module are multiplied in the digital multiplier, and the processing module outputs distance information of a final detected object according to the distance-related signal.

[0016] Optionally, the driving signal generation unit generates a chirp signal as the modulation sequence. The modulation sequence modification module generates a modified sequence, and the modified modulation sequence is obtained according to the modified sequence and the modulation sequence.

[0017] In a second aspect, the present application provides a laser radar detection device, characterized in that the device comprises a driving signal generation unit, a laser source, a laser modulation driving circuit, an array-type return light receiving module, and a processing module. The driving signal generation unit drives the laser source to emit a pulse-type detection laser sequence through the laser modulation driving circuit. The array-type return light receiving module receives a return light signal reflected by a detected object in a field of view and generates a return signal. The processing module obtains a distance-related signal according to the return signal according to a preset rule. An accumulated count sequence modification module modifies the distance-related signal to obtain a modified accumulated count sequence. The processing module outputs distance information of a final detected object according to the modified accumulated count sequence.

[0018] Optionally, the laser radar detection device further comprises a digital multiplier, the modulation sequence and the return signal are multiplied in the digital multiplier, and a distance-related signal is obtained according to a preset rule.

[0019] Optionally, the laser radar detection device further comprises a count sequence splicing module, the modulation sequence and a signal output by the count sequence splicing module are multiplied in the digital multiplier, and a distance-related signal is obtained according to a preset rule.

[0020] Optionally, the laser radar detection device further comprises a count sequence generation module, the modulation sequence and a signal output by the count sequence generation module are multiplied in the digital multiplier, and a distance-related signal is obtained according to a preset rule.

[0021] Optionally, the accumulated count sequence modification module generates an accumulated modified sequence, and the modified accumulated count sequence is obtained according to the accumulated modified sequence and the distance-related signal.

[0022] The beneficial effects of the present application are: the present application provides a laser radar detection system, characterized in that it comprises a driving signal generation part, the driving signal generation part acts on a laser source through a laser modulation driving circuit, the laser source receives the driving signal to drive to emit a pulse type detection laser sequence; a modulation sequence correction module, the modulation sequence correction module receives the driving signal to generate a corrected modulation sequence; an array type return light receiving module, which receives the return light signal reflected by the detected object in the field of view and generates a return signal; a processing module, the processing module generates a corrected modulation sequence according to the corrected modulation sequence generated by the modulation sequence correction module, and calculates a distance related signal according to the return signal according to a preset rule, and the processing module outputs the distance information of the final detected object according to the distance related signal, so that the constraint condition can be broken and the flexible configuration of parameters under different applications can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0024] Figure 1 A schematic diagram of the modular working principle of the detection system provided by the embodiments of the present application;

[0025] Figure 2 A pulse detection scheme implementation schematic diagram provided by the embodiments of the present application;

[0026] Figure 3 A schematic diagram of obtaining distance related signal provided by the embodiments of the present application;

[0027] Figure 4 A three-dimensional imaging system schematic diagram provided by the embodiments of the present application;

[0028] Figure 5 A detection system schematic diagram provided by the embodiments of the present application;

[0029] Figure 6 Another detection system schematic diagram provided by the embodiments of the present application;

[0030] Figure 7 A modulation correction detection system schematic diagram provided by the embodiments of the present application;

[0031] Figure 8 Another modulation correction detection system schematic diagram provided by the embodiments of the present application;

[0032] Figure 9 Yet another modulation correction detection system diagram provided for embodiments of the present application;

[0033] Figure 10 A waveform diagram provided for embodiments of the present application;

[0034] Figure 11 A correction detection system diagram provided for embodiments of the present application;

[0035] Figure 12 Another correction detection system diagram provided for embodiments of the present application;

[0036] Figure 13 Yet another correction detection system diagram provided for embodiments of the present application;

[0037] Figure 14 Another waveform diagram provided for embodiments of the present application. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work, fall within the scope of protection of the present application.

[0040] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0041] The current detection system basically includes: light source module 110, processing module 120, and light receiving module 130, the light source module 110 includes but is not limited to semiconductor laser, solid-state laser, and can also include other types of lasers, when the semiconductor laser is used as the light source, the vertical cavity surface emitting laser VCSEL (Vertical-cavity surface-emitting laser) or the edge-emitting semiconductor laser EEL (edge-emitting laser) can be used, here is only exemplary description and is not specifically limited, the light source module 110 emits sine wave or square wave or triangular wave, or pulse wave and the like, in the distance measurement application, it is mostly laser with certain wavelength, for example, 950nm and the like infrared laser (optimally near-infrared laser), the emitted light is projected to the field of view, the detected object 140 existing in the field of view can reflect the projected laser to form return light, the return light enters the detection system and is captured by the light receiving module 130, the light receiving module 130 can include a photoelectric conversion part, wherein in the ITOF distance measurement, the most commonly used four-phase delay receiving can obtain 0°, 90°, 180° and 270° delay receiving signals, using the four-phase distance calculation scheme, here taking the sine wave method as an example for description, the amplitudes of the received signals are measured at four equidistant points (for example, 90° or 1 / 4λ interval):

[0042]

[0043] The ratio of the difference between A1 and A3 to the difference between A2 and A4 is equal to the tangent value of the phase angle. ArcTan is actually a two-variable inverse tangent function, which can be mapped to the appropriate quadrant, when A2=A4 and A1>A3 or A3>A1, it is defined as 0° or 180° respectively.

[0044] The distance to the target object is determined by the following formula:

[0045]

[0046] At this point, the frequency of the emitted laser also needs to be determined to calculate the distance, wherein c is the speed of light, is the phase angle (measured in radians), and f is the modulation frequency. Through the above scheme, the distance detection effect of the detected object in the field of view can be realized, and the four-phase delay scheme is used to obtain the detection result, of course, the photoelectric conversion of the receiving module generates different information, in some cases, the 0° and 180° two-phase scheme is also used to realize the information acquisition of the detected object, some documents also disclose that the 0°, 120° and 240° three-phase scheme is used to obtain the target information, and even some documents also disclose the five-phase delay scheme, and the present application is not specifically limited.

[0047] In DTOF ranging, the pixel unit of the array sensor is a SPAD (single photon avalanche photodiode) device, which works in Geiger mode. In Geiger mode, the avalanche photodiode absorbs photons to generate electron-hole pairs, which are accelerated under the action of a strong electric field generated by a high reverse bias voltage, thereby obtaining sufficient energy, and then colliding with the lattice to form a chain effect, resulting in a large number of electron-hole pairs, triggering an avalanche phenomenon, and the current grows exponentially. At this time, the gain of the SPAD is theoretically infinite, and a single photon can make the photocurrent of the SPAD reach saturation, so the SPAD becomes the first choice for high-performance single-photon detection systems. The ranging principle is actually very simple. The light source emits pulsed laser with a certain pulse width, for example, several nanoseconds. The pulsed laser is reflected by the detection target and returns to the array type receiving module containing the SPAD in the avalanche state. The detection unit in the avalanche state can receive the returned signal, and the processing module can output the distance between the detection system and the detection target after processing, thereby completing the detection. In order to obtain a high reliability result, tens of thousands of laser pulses can be emitted, and the detection unit obtains a statistical result. In this way, by processing the statistical result, a more accurate distance can be obtained. Table 1 below is a comparison of two typical ITOF ranging methods and DTOF ranging methods applied by the applicant of the present application. As can be seen from Table 1, the two commonly used time-of-flight ranging schemes have certain limitations, and a new detection method needs to be developed to obtain more accurate and stronger anti-interference results.

[0048] Table 1. Comparison of ITOF and DTOF ranging methods

[0049]

[0050] Figure 2 A pulse detection scheme implementation schematic diagram is provided for the embodiments of the present application, as shown in Figure 2As shown, the system adopts a pulsed laser, so the emitted active detection laser is a pulsed laser sequence segment composed of a pulse sequence. The driving signal generation unit in the system generates a driving signal. The driving signal here can adopt a chirp signal similar to the previous example, or other types of driving signals. The essential feature of the driving signal here is to modulate the laser emission of the device to obtain an emission light signal with identifiable characteristics. The driving signal acts on the pulsed laser through the laser modulation driving circuit. The laser can use at least part of the characteristics of the driving signal, such as the total period of the driving signal as the period of the pulse sequence segment. The individual pulses in the pulse segment can be selected to have the same or similar peak values and the same or similar peak duration. Or the amplitude information of the driving signal is used as the peak value of the pulse sequence. At this time, the peaks contained in the pulse sequence can be different. Even the decreasing or increasing law of the small period in the segment of the driving signal can be used as the basis for the pulse triggering probability in the emitted laser segment to generate a non-equidistantly configured pulsed laser segment, etc. Here, the specific implementation scheme of the pulsed laser source emitted by the pulsed laser source is not limited. The emitted pulsed laser sequence is reflected by the detected object in the field of view to generate a return light signal. The return light signal is received by the photodetector to form a photon counting sequence. At this time, the preset rule operation module contained in the processing module utilizes the driving signal to generate a non-continuous modulation sequence Y on one hand, and on the other hand, the distance-related signal can be obtained by operating the photon counting sequence and the modulation sequence Y according to the preset rule. The distance-related signal is converted into a frequency spectrum signal through the time-frequency domain conversion module. The characteristics of the frequency spectrum signal, such as the peak value characteristics (including the highest peak value information, the second highest peak value information, or the peak value information in the region of interest, etc.), are used to output the distance information of the detected object, which can also contain speed information, etc. Here, the specific implementation is not limited. Similarly, for the pulsed type of non-continuous detection scheme, the time-frequency domain conversion module contains a unit that can perform time-frequency domain conversion processing, which can perform wavelet operation, segmented FFT, FFT, chirp-Z operation, DFT, etc. Of course, the specific algorithm implementation is not described in detail here. Here, only an example is given. Of course, the time-frequency domain conversion module can also contain a threshold detection unit and / or an information solving unit, which is not limited here.

[0051] Here still take the chirp signal generator as an example for example description, on the one hand, the chirp signal generator generates a chirp signal as a modulation sequence Y, the modulation sequence here can be the aforementioned for the example of the discretization of the continuous signal, and finally convert into a digital type modulation sequence signal, here the period selection of laser emission is the chirp signal period T (that is, the total duration selection in the fragment of emitting laser is the period characteristic of the chirp signal), on the other hand, the chirp signal generator controls the laser modulation drive circuit to generate a pulsed laser drive signal, the pulsed laser drive signal controls the pulsed laser to emit a laser pulse sequence, and the emission optical system projects the laser pulse sequence to the target area; the energy of each laser pulse in the laser pulse sequence is equal, here only one case is exemplarily listed, the receiving system includes a receiving optical system, a photodetector, a digital correlator, a digital integral accumulator and the like, wherein the receiving optical system focuses the laser pulse sequence reflected back by the target to the photodetector, the photodetector starts to detect when the laser pulse sequence is emitted, and the photon counting result in the emission period of the laser pulse sequence is obtained; in order to ensure that the subsequent calculation result operation amount is small, first, the scene in the field of view is irradiated by L times of emitted pulse sequences (wherein L is an integer greater than or equal to 1), and more optimally, in order to obtain more accurate detection results, L can be selected to be of the order of hundreds, thousands or the like, which is not limited here, of course, in order to ensure the accuracy of the data or the effect of fast and accurate operation, etc., this place also does not limit to obtain the statistical value by counting all the detection results of the L times, here the statistical result of the excitation information of the returned light of less than or equal to L times can be used to generate the statistical photon counting sequence X, for example, the following scene is one example to explain the generation and construction scheme of the statistical photon sequence X, the laser pulse sequence reflected back by the target is cumulatively detected for L times (L is a positive integer and L≥1), each cumulative detection includes M (M is a positive integer and M≥1) detection pulses, and the photon counting result of the i th (i is a positive integer and 1≤i≤M) detection pulse in the d th (d is a positive integer and 1≤d≤L) cumulative detection is x di , so as to obtain the basic counting sequence X composed of M detection pulse counting results:

[0052]

[0053] First, L times of cumulative detection are performed, and the basic counting sequence X obtained after L times of cumulative detection is obtained (X is the accumulation of L X d ), then X is multiplied by Y to obtain Z (Z is the accumulation of L Z d ), and then S is obtained by segmenting and accumulating Z.

[0054] Figure 3 It can also be explained as another detailed scheme description for implementing the scheme of the application, in combination with Figure 3To be described, the laser source emits a sequence of L pulses, the reflected probe laser of the detected object in the field of view is received at the return light photon statistical result X, which can be L times of return results, the modulation sequence can be modulated according to each output modulation sequence and each return photon statistical sequence to perform multiplication operation to obtain the modulated statistical sequence Z, and finally perform segmented accumulation to obtain the final count sequence S. This scheme is also one of the schemes protected by the present application. The execution steps are as follows: first, use a pulse sequence to obtain X d ,

[0055] X d ={x di |i=1,2,...,N} (4)

[0056] Similar to the above scheme, a non-continuous modulation sequence Y is obtained, and then X d is multiplied by Y to obtain Z d ,

[0057] Z H ={z di |z di =x di ·y i ,i=1,2,...,N} (5)

[0058] Then, Z d is segmented and accumulated to obtain S d , which is similar to the segmented accumulation scheme shown in formula 13. Of course, this is only a schematic case, and the actual implementation is not limited to this way. The difference from the previous one is that this scheme may require more calculation, and under the requirement of fast output, a more optimized scheme is needed to realize the detection, which is not limited here.

[0059] The photon count sequence or accumulated photon count sequence in the above embodiment can not only be generated by the laser pulse sequence received by the photodetector array, but also by the environmental background light received by the photodetector array, including natural background light and unnatural background light. In addition, when the photodetector array does not receive photons, only the photodetector array itself causes, such as dark count of Geiger mode APD photodetector array, count caused by readout circuit noise, etc. will also produce photon count sequence or accumulated photon count sequence. Among them, the photon count results generated by environmental background light, photodetector array itself and the like will reduce the signal-to-noise ratio of the detection system and cause the detection performance to deteriorate.

[0060] Since natural background light, such as sunlight, and the counting results generated by the detector array itself usually follow certain statistical laws, these statistical laws can be determined based on the photon counting sequence or the accumulated photon counting sequence. On the other hand, since the generation rules of laser pulse sequences and the photon counting laws generated by them are known, the photon counting statistical laws generated by non-natural background light interference, such as interference light from other detection devices, can be distinguished from the photon counting sequence or the accumulated photon counting sequence. Based on the photon counting statistical laws generated by the ambient background light and the detector array itself, the photon counting sequence or the accumulated photon counting sequence generated by the photodetector array can be corrected, thereby improving the signal-to-noise ratio and detection performance of the detection system.

[0061] To mitigate the aforementioned problems, in some embodiments a counting sequence generation module is added to the receiving system. Its function is to acquire the statistical characteristics of the photon counting sequence or the accumulated photon counting sequence, and generate an adaptive counting sequence or an accumulated adaptive counting sequence according to a preset rule.

[0062] Figure 4 A schematic diagram of a three-dimensional imaging system provided in an embodiment of this application; Figure 4 Compared to Figure 3 An additional counting sequence generation module has been added; the functions of other modules are the same. Figure 3 As shown, it will not be repeated here. Figure 4 The photon counting sequence generation module generates an adaptive counting sequence based on the statistical characteristics of the photon counting sequence and preset rules. The photon counting sequence X... d With adaptive correction sequence X dm ={x dmi The sequence |i=1,2,...,N} is processed according to a predefined set of rules, thereby changing the photon counting sequence X. d The number of high-value elements in the sequence is used to obtain the adaptive counting sequence X. da For example, calculations can be performed according to the preset rules of formula (6):

[0063]

[0064] Get X da The subsequent signal processing is the same as in the aforementioned embodiments, and will not be repeated here.

[0065] Figure 5 This is a schematic diagram of a detection system provided in an embodiment of this application. Figure 5 As shown, it is similar to Figure 2 The difference in the illustrated embodiment is that a counting sequence replication and splicing module is added between the photodetector and the digital multiplier in this detection system; the other modules are the same as... Figure 2 The embodiments shown are the same and will not be repeated here. Figure 5In the embodiment shown, the counting sequence copying and splicing module copies the photon counting sequence X. d Transform into a copy splicing sequence X c :

[0066] X c ={x ci |i=1,2,...,N} (7)

[0067] The digital multiplier yields the modulated counting sequence Zd:

[0068] Z d ={z di |z di =x ci ·y i ,i=1,2,...,N} (8)

[0069] The preset rule operation module performs operations on the modulation counting sequence Z. d Perform segmented accumulation to obtain the segmented accumulation counting sequence S. d :

[0070]

[0071] In the formula, N0 is the integer whose value is closest to N / M, and K is an integer and (R max (Maximum detectable distance).

[0072] The preset rule calculation module accumulates the L segmented cumulative count sequences obtained during the L laser pulse sequence emission process to obtain the cumulative count sequence S:

[0073]

[0074] Figure 6 This is a schematic diagram of another detection system provided in an embodiment of this application. For example... Figure 6 The illustrated embodiment is similar to Figure 4 The difference in the illustrated embodiment is that a counting sequence replication and splicing module is added between the photodetector and the counting sequence generation module in this detection system; the other modules are the same as... Figure 4 The embodiments shown are the same and will not be described again here.

[0075] exist Figure 5 and Figure 6 In the illustrated embodiment, the counting sequence copying and splicing module copies the photon counting sequence X. d One or more elements in the sequence, and compare them with the photon counting sequence X. d The concatenated sequence X is obtained by splicing. c The subsequent imaging principle is similar to that described in Embodiment 2 above, and will not be repeated here.

[0076] Figure 7 This is a schematic diagram of another detection system provided in the embodiments of this application, such as... Figure 7 The detection system shown includes a drive signal generator (generating a modulation sequence Y and laser drive parameters), a laser modulation drive circuit (modulating and driving the pulsed laser), a pulsed laser (generating a laser pulse sequence), and an emission optical system (shaping and expanding the laser pulse sequence to illuminate the target area); on one hand, the drive signal generator generates a chirped signal as the modulation sequence Y.

[0077] Y = {y i |y i =cos[2πf0(i-1)Δt+πk(i-1)] 2 Δt 2 +φ Y ],i=1,2,...,N} (11)

[0078] In the formula, f0 is the starting frequency of the chirped signal, B is the bandwidth of the chirped signal, T is the period of the chirped signal, k is the frequency modulation slope and k = B / T, Δt is the system time step interval and NΔt = T; on the other hand, the drive signal generator produces laser drive parameters, which control the laser modulation drive circuit to generate laser drive signals, control the pulsed laser to emit a laser pulse sequence, and the emitting optical system shapes and expands the laser pulse sequence to irradiate the target area; the energy of each laser pulse in the laser pulse sequence is equal or unequal; the laser pulse repetition frequency is f s The emission period of the laser pulse sequence is equal to the chirped signal period T, and each laser pulse sequence consists of M0 ≤ M = f s It consists of T (M is a positive integer) laser pulses.

[0079] Figure 7 The receiving system shown includes a receiving optical system, a photodetector, a counting sequence generation module, a digital multiplier, and a preset rule operation module. The receiving optical system focuses the laser pulse sequence reflected from the target onto the photodetector. The photodetector begins detection when the laser pulse sequence is emitted. Assuming a total of L (L is an integer greater than or equal to 1) laser pulse sequences are emitted, the photon counting sequence obtained by the photodetector when detecting the d-th (d is a positive integer and d ≤ L) laser pulse sequence is Xd.

[0080] X d ={x di |i=1,2,K,N} (12)

[0081] The digital multiplier produces the modulation counting sequence Z. d :

[0082] Zd = {z di |z di = x di y i , i = 1, 2, K, N} (13)

[0083] The preset rule operation module accumulates the L segmented accumulated count sequences obtained in the L laser pulse sequence emission process to obtain an accumulated count sequence S:

[0084]

[0085] Figure 8 On the basis of the embodiment shown in Figure 7 , a count sequence copying and splicing module is added, and other principles are similar to the embodiment shown in Figure 7 , and thus will not be described here again. In the embodiment shown in Figure 8 , the count sequence copying and splicing module converts the photon count sequence X d into a copied and spliced sequence X c :

[0086] X c = {x ci |i = 1, 2,..., N} (15)

[0087] The digital multiplier obtains a modulated count sequence Z d :

[0088] Z d = {z di |z di = x ci · y i , i = 1, 2,..., N} (16)

[0089] The preset rule operation module performs segmented accumulation on the modulated count sequence Z d to obtain a segmented accumulated count sequence S d :

[0090]

[0091] In the formula, N0 is an integer closest to N / M, K is an integer and (R max is the maximum detectable distance).

[0092] Figure 9 On the basis of the embodiment shown in Figure 7 , a count sequence generation module is added. Other principles are similar to the embodiment shown in Figure 7 , and thus will not be described here again. In the embodiment shown in Figure 9 , the count sequence generation module generates a sequence X daWith modified modulation sequence Y m Multiplying them in a digital multiplier yields the modulation counting sequence Z. d :

[0093] Z d ={z di |z di =x dai y i ,i=1,2,K,N} (18)

[0094] The cumulative count sequence S is obtained according to the preset rules.

[0095] In another embodiment, the counting sequence copying and splicing module and the counting sequence generation module described in the above embodiments can be combined with... Figure 7 The embodiments shown can be combined in any way, and the present invention does not impose any specific limitations. The principle is similar to that of the embodiments described above, and will not be repeated here.

[0096] The above embodiments include an added modulation sequence correction module that generates a corrected sequence M. Y And according to the corrected sequence M Y Generate a modified modulation sequence Y from the modulation sequence Y. m In one implementation, the modulation sequence Y is modified. m From the corrected sequence M Y The waveform is obtained by multiplying the modulation sequence Y, as shown in the figure below. Figure 10 As shown:

[0097] Y m =M Y ·Y (19)

[0098] Among them, the corrected sequence M Y Based on the modulation sequence Y and the laser pulse repetition frequency f s Parameters are generated. In one implementation, the modified sequence M is... Y It is generated using the following formula, which contains N elements:

[0099]

[0100] Wherein, the modulation sequence Y = {y i ,i=1,2,...,N} is a linear frequency modulated continuous wave, given by equation (11). Furthermore, N1 is greater than or equal to 1 and less than or equal to N. s Integers.

[0101] The digital multiplier will count the photon sequence X d Copy and splice sequence X c Or adaptive counting sequence X da With modified modulation sequence Y mMultiplying, the modulation count sequence Z is obtained d The preset rule operation module obtains the accumulated count sequence S according to the modulation count sequence Z d The time-frequency domain conversion module calculates the frequency spectrum of the accumulated count sequence S, thereby obtaining the distance correlation signal frequency spectrum result, and the target distance is solved.

[0102] Figure 11 On the basis of Figure 2 , the accumulated count sequence correction module is added, which generates the accumulated count correction sequence M S , and generates the corrected accumulated count sequence S S according to the accumulated count correction sequence M m and the accumulated count sequence S. In an implementation manner, the corrected accumulated count sequence S m is obtained by multiplying the accumulated count correction sequence M S and the accumulated count sequence S. The partial waveform diagram in the second detection scheme of the new patent is shown in Figure 14 :

[0103] S m =M S ·S (21)

[0104] Wherein, the accumulated count correction sequence M S is generated according to the modulation sequence Y and the laser pulse repetition frequency f s and other parameters. In an implementation manner, the accumulated count correction sequence M S is generated by the following formula, containing f s T elements:

[0105] M S ={m Si |m Si =y i ,i=aN s +1,a=0,1,...,f s T-1} (22)

[0106] Wherein, the modulation sequence Y={y i ,i=1,2,...,N} is a linear frequency modulation continuous wave, which is given by formula (7) and formula (23).

[0107] The time-frequency domain conversion module calculates the frequency spectrum of the corrected accumulated count sequence S m , thereby obtaining the distance correlation signal frequency spectrum result, and the target distance is solved.

[0108] Figure 12 In the embodiment described in Figure 11 , the count sequence copying and splicing module is added, and other module functions and Figure 11 the embodiment are the same and will not be described here.

[0109] Figure 13 In Figure 11 The counting sequence generation module is added in the embodiment shown, and other module functions and Figure 11 The same as the embodiment, and will not be described here.

[0110] In another embodiment, the counting sequence copy and splice module, the counting sequence generation module and Figure 11 The embodiment shown, the present application does not make specific limitations. Its principle is similar to the principle of the above-mentioned embodiment, and will not be described here.

[0111] Of course, the modulation sequence correction module and the accumulated counting sequence correction module mentioned in the above-mentioned embodiment can also be combined arbitrarily, and the present application does not make specific limitations. Its principle is similar to the principle of the above-mentioned embodiment, and will not be described here.

[0112] In addition to the above-mentioned non-coherent chirp signal amplitude modulation continuous wave laser three-dimensional imaging technology (hereinafter referred to as technology 1), the prior art mainly includes non-coherent sinusoidal / pulse amplitude modulation laser three-dimensional imaging technology (itof, hereinafter referred to as technology 2) and pulse photon counting laser three-dimensional imaging technology (dtof, hereinafter referred to as technology 3). Compared with the above-mentioned technologies, the present application has the following advantages:

[0113] (1) Compared with technology 1, the present application uses pulse laser for detection, avoiding the problem of waste of laser emission energy in the A / D sampling interval of technology 1, thus greatly improving the energy utilization rate and reducing the average emission power of the laser;

[0114] (2) Compared with technology 1, the present application does not use a wideband amplifier, a mixer and an A / D device in the receiving system, avoiding the problem that the above-mentioned devices limit the dynamic range of the received laser signal, so that the receiving system of the present application has a larger dynamic receiving range;

[0115] (3) Compared with technology 1, the present application uses a digitized chirp signal as a modulation sequence in the receiving system, and uses a digital multiplier to realize sequence multiplication, reducing the influence of chirp signal frequency modulation linearity and frequency modulation flatness on the ranging performance;

[0116] (4) Compared with technology 2, the present application uses a chirp signal for correlation reception, so it has distance resolution and can effectively avoid the influence of multipath effect;

[0117] (5) Compared with technology 2, the present application improves the anti-light interference ability by using correlation reception, Fourier analysis and spectrum detection, so the ranging performance is less affected by light interference, and the required laser energy is smaller under the same detection condition;

[0118] (6) Compared with technology 2, the application no longer uses A / D, and has a larger dynamic receiving range;

[0119] (7) Compared with technology 3, the application needs to transmit the accumulated count sequence instead of the photon count sequence, so that the data transmission amount is greatly reduced;

[0120] (8) Compared with technology 3, the application extracts target distance information from the frequency spectrum, so that the influence of pulse shape distortion on the ranging performance is reduced;

[0121] (9) Compared with technology 3, the application improves the anti-light interference capability by using correlation receiving, Fourier analysis and frequency spectrum detection, so that the ranging performance is less affected by light interference.

[0122] The application utilizes multiple direct receiving to form a distance-amplitude spectrum (frequency domain), and determines the time of flight by threshold detection in the frequency domain and the spectrum peak value, and the spectrum amplitude threshold value can be adaptively set in the specific implementation; the spectrum peak value can also be accurately determined, the overall scheme is of a digital framework structure type, and a large number of FFT points can be used to ensure the accuracy; on the premise of a large amount of calculation, the detection accuracy and precision can be ensured, the cumulative charge is introduced in the exposure time, the background light interference problem is suppressed from the algorithm level through FFT and correlation receiving (zero-mean FMCW correlation signal), the emission power is completely received in the energy utilization aspect, and the highest efficiency of energy utilization is achieved. The entire system and method solve some problems of the existing schemes, have wide application prospects and popularization value.

[0123] It should be noted that the terms “include”, “contain” or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement “including a” does not exclude the presence of another identical element in the process, method, article or equipment including the element.

[0124] The above descriptions are only the preferred embodiment of the present application, but not intended to limit the present application. Various modifications and changes can be carried out by those skilled in the art, which should be included in the scope of the present application so far as these modifications and changes do not deviate from the spirit and principle of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it need not be further defined and explained in the subsequent drawings. The above descriptions are only the preferred embodiment of the present application, but not intended to limit the present application. Various modifications and changes can be carried out by those skilled in the art, which should be included in the scope of the present application so far as these modifications and changes do not deviate from the spirit and principle of the present application.

Claims

1. A lidar detection system, characterized in that, It includes a drive signal generator, which acts on a laser source through a laser modulation drive circuit. The laser source receives the drive signal and drives it to emit a pulsed probe laser sequence. The drive signal generator generates a chirped signal as a modulation sequence. A modulation sequence correction module receives the driving signal to drive the generation of a correction sequence, and obtains a corrected modulation sequence based on the correction sequence and the modulation sequence; An array-type return light receiver module receives the return light signal reflected by the object being detected within the field of view and generates a return signal; The processing module calculates a distance-related signal based on the modified modulation sequence generated by the modulation sequence correction module and the returned signal according to a preset rule. The processing module then outputs the final distance information of the detected object based on the distance-related signal. The correction sequence is generated based on the modulation sequence and the laser pulse repetition frequency parameter.

2. The lidar detection system according to claim 1, characterized in that, The lidar detection system also includes a digital multiplier. The modified modulation sequence and the return signal are multiplied by the digital multiplier and then processed according to a preset rule to obtain a distance-related signal. The processing module outputs the final distance information of the detected object according to the distance-related signal.

3. The lidar detection system according to claim 2, characterized in that, The lidar detection system also includes a counting sequence splicing module. The modified modulation sequence and the signal output by the counting sequence splicing module are multiplied by the digital multiplier and then processed according to a preset rule to obtain a distance-related signal. The processing module outputs the final distance information of the detected object according to the distance-related signal.

4. The lidar detection system according to claim 2, characterized in that, The lidar detection system also includes a counting sequence generation module. The modified modulation sequence and the signal output by the counting sequence generation module are multiplied by the digital multiplier and then processed according to a preset rule to obtain a distance-related signal. The processing module outputs the final distance information of the detected object according to the distance-related signal.

5. A lidar detection device, characterized in that, It includes a drive signal generator, which acts on a laser source through a laser modulation drive circuit. The laser source receives the drive signal and drives it to emit a pulsed probe laser sequence. The drive signal generator generates a chirped signal as a modulation sequence. An array-type return light receiver module receives the return light signal reflected by the object being detected within the field of view and generates a return signal; The processing module calculates a distance-related signal based on the returned signal according to a preset rule. An accumulation count sequence correction module generates an accumulation correction sequence and obtains a corrected accumulation count sequence based on the accumulation correction sequence and the distance correlation signal; The processing module outputs the final distance information of the detected object according to the corrected cumulative counting sequence; The modified cumulative count sequence is generated based on the modulation sequence and the laser pulse repetition frequency parameter.

6. The lidar detection device according to claim 5, characterized in that, The lidar detection device also includes a digital multiplier. After the modulation sequence and the return signal are multiplied by the digital multiplier, a distance-related signal is obtained by calculation according to a preset rule.

7. The lidar detection device according to claim 6, characterized in that, The lidar detection device also includes a counting sequence splicing module. The modulation sequence and the signal output by the counting sequence splicing module are multiplied by the digital multiplier and then calculated according to a preset rule to obtain a distance-related signal.

8. The lidar detection device according to claim 6, characterized in that, The lidar detection device further includes a counting sequence generation module. The modulation sequence and the signal output by the counting sequence generation module are multiplied by the digital multiplier and then calculated according to a preset rule to obtain a distance-related signal.

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