LiDAR device and operating method thereof

Abstract

A method for operating a light detection and ranging (LiDAR) device, comprising: obtaining a main received signal having a maximum value relative to any one time point; correcting a value of a sub-received signal at that time point by using the value of the main received signal at that time point; and obtaining a time of flight (ToF) of a laser pulse from the corrected sub-received signal.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2019-0149115, filed on November 19, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to LiDAR devices and methods of operating the same. Background Art

[0004] Light detection and ranging (LiDAR) devices are used in various fields such as aerospace, geology, 3D mapping, vehicles, robots, or drones. LiDAR devices use a method of measuring the time of flight (ToF) of light as a basic operating principle. For example, a LiDAR device can illuminate an object with light and receive the light through a sensor, and can measure the ToF by using a high-speed circuit. In addition, the LiDAR device can calculate the distance to the object from the ToF and generate a depth image of the object by using the distance calculated for each position of the object.

[0005] Meanwhile, in order to enable the LiDAR device to accurately process a depth image even in an environment where side lobes are generated, a technology for measuring ToF of light may be required. Summary of the Invention

[0006] Various embodiments provide a light detection and ranging (LiDAR) device and an operating method thereof. The technical objectives to be achieved by the present disclosure are not limited to the above objectives, and other technical objectives can be inferred from the following embodiments.

[0007] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the embodiments presented herein.

[0008] Among them, according to one aspect of the present disclosure, a method of operating a LiDAR device includes: obtaining a received signal corresponding to a laser pulse generated from a reference signal; obtaining a main received signal having a maximum value relative to any time point in the received signal; correcting the value of a sub-received signal included in the received signal at the time point by using the maximum value; and obtaining the time of flight (ToF) of the laser pulse corresponding to the sub-received signal by using the correlation between the corrected sub-received signal and the reference signal.

[0009] According to another aspect of the present disclosure, there is provided a non-transitory computer-readable recording medium having recorded thereon a program for executing the above-mentioned method.

[0010] According to another aspect of the present disclosure, a LiDAR device includes: an antenna unit configured to transmit and receive laser pulses; and a processor, which obtains a received signal corresponding to the laser pulse generated from a reference signal, obtains a main received signal having a maximum value relative to any one time point in the received signal, corrects the value of a sub-received signal included in the received signal at the time point by using the maximum value; and obtains the ToF of the laser pulse corresponding to the sub-received signal by using a correlation between the corrected sub-received signal and the reference signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and other aspects, features and advantages of some embodiments of the present disclosure will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0012] Figure 1 is a block diagram of an example of a light detection and ranging (LiDAR) device according to an embodiment.

[0013] Figure 2 is a block diagram of an example of an antenna unit according to an embodiment.

[0014] Figure 3 is a block diagram of an example of a transmitter according to an embodiment.

[0015] Figure 4 An example of a radiation pattern of a LiDAR device according to an embodiment is shown.

[0016] Figure 5 An example of measuring distance using a LiDAR device according to an embodiment is shown.

[0017] Figure 6 An example of a method of obtaining an angle at which a side lobe is generated according to an embodiment is shown.

[0018] Figure 7 An example of a method of operating a LiDAR device according to an embodiment is shown.

[0019] Figure 8 An example of a method of correcting a received signal according to an embodiment is shown.

[0020] Figure 9 Another example of the method of correcting a reception signal according to the embodiment is shown.

[0021] Figure 10 An example of a method of obtaining ToF according to an embodiment is shown.

[0022] Figure 11 is a flowchart of a method of operating a LiDAR device according to an embodiment.

[0023] Figure 12Included are diagrams for describing experiments of measuring distance using a LiDAR device according to an embodiment.

[0024] Figure 13 Experimental results according to the first scenario according to an embodiment are shown.

[0025] Figure 14 Experimental results according to the second scenario according to the embodiment are shown.

[0026] Figure 15 A vehicle including a LiDAR device is shown according to an example embodiment. DETAILED DESCRIPTION

[0027] Reference will now be made in detail to the embodiments, examples of which are shown in the accompanying drawings, wherein the same reference numerals throughout the drawings represent the same elements. In this regard, the embodiments presented may have different forms and should not be construed as being limited to the description set forth herein. Therefore, the embodiments are described below solely with reference to the accompanying drawings to explain various aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. Expressions such as "at least one of..." modify the entire list of elements when following a list of elements, rather than modifying the individual elements in the list.

[0028] The terms used in the embodiments have been selected from commonly used terms, taking into account their functions in the present disclosure. However, these terms may vary depending on the intentions of those skilled in the art, case precedents, and the emergence of new technologies. In addition, for special cases, the meanings of the terms selected by the applicant will be explained in detail in the description. Therefore, the terms used in this disclosure are defined based on their meanings in relation to the content discussed throughout the specification, rather than by their simple meanings.

[0029] Terms such as “include” or “comprising” should not be interpreted as necessarily including any and all constituent elements or steps described in the specification, but may be interpreted as excluding some constituent elements or steps or including additional constituent elements or steps.

[0030] Hereinafter, the embodiment will be described in detail with reference to the accompanying drawings. However, the embodiment can be implemented in various forms and is not limited to the examples described below.

[0031] Figure 1 is a block diagram of an example of a light detection and ranging (LiDAR) device 100 according to an embodiment.

[0032] Reference Figure 1 , the LiDAR device 100 may include an antenna unit 110 and a processor 120 . Figure 1The LiDAR device 100 is shown to include only the constituent elements related to the embodiment. Therefore, it is obvious to those skilled in the art that, in addition to Figure 1 In addition to the components of FIG1 , other general components may be included in the LiDAR device 100. For example, the LiDAR device 100 may further include a memory 130.

[0033] The memory 130 is hardware for storing various data processed in the LiDAR device 100, and may store, for example, data processed or to be processed in the LiDAR device 100. In addition, the memory 130 may store applications or driver programs to be executed by the LiDAR device 100.

[0034] The memory 130 may include random access memory (RAM), such as dynamic random access memory (DRAM) and static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), CD-ROM, Blu-ray or other optical disk storage, hard disk drive (HDD), solid-state drive (SSD), or flash memory, as well as other external storage devices accessible to the LiDAR device 100.

[0035] Antenna unit 110 can perform the following functions: convert electrical signals into laser pulses and transmit the converted laser pulses, or receive laser pulses and convert the received laser pulses into electrical signals. The laser pulses transmitted by antenna unit 110 can be light pulses or electromagnetic radiation pulses. Antenna unit 110 can include a transmitter for transmitting laser pulses and a receiver for receiving laser pulses. In addition, antenna unit 110 can include a transceiver for transmitting / receiving laser pulses.

[0036] The processor 120 may perform overall functions to control the LiDAR device 100. The processor 120 may be implemented by an array of multiple logic gates, or by a combination of a general-purpose microprocessor and a memory for storing programs executable in the microprocessor. Furthermore, the processor 120 may include a signal processor for processing optical or electrical signals and a computing unit for calculating a signal value indicated by the signal.

[0037] When processor 120 generates a reference signal, antenna unit 110 may convert the reference signal into a laser pulse and transmit the converted laser pulse. The transmitted laser pulse may be reflected by an object and received by antenna unit 110. Antenna unit 110 may convert the received laser pulse into a received signal and transmit the received signal to processor 120.

[0038] Processor 120 can calculate the ToF of the laser pulse by using the correlation between the received signal and a reference signal. The received signal has characteristics identical or similar to those of the reference signal. The received signal is the signal obtained by antenna unit 110 when a laser pulse generated based on the reference signal is reflected from an object. Therefore, when the time point at which the correlation between the received signal and the reference signal is high is detected, the time point at which the laser pulse emitted by transmitter 210 is received by receiver 220 can be detected, thereby detecting the ToF of the laser pulse.

[0039] For example, processor 120 may calculate a cross-correlation function between the received signal and the reference signal. Because the cross-correlation function indicates the degree of correlation between two functions, the cross-correlation function between the received signal and the reference signal may output a value proportional to the degree of correlation between the two signals. For example, assuming that the received signal is f0(t) and the reference signal is g0(t), the cross-correlation function between the received signal and the reference signal may be calculated using the following mathematical expression 1.

[0040] [Mathematical expression 1]

[0041]

[0042] The processor 120 may determine the time point at which the calculated value of the cross-correlation function is the maximum. Alternatively, the processor 120 may determine the time point at which the calculated value of the cross-correlation function exceeds a preset threshold. The preset threshold may be determined by the processor 120, but the present disclosure is not limited thereto. The preset threshold may be determined by an external input.

[0043] The processor 120 may determine the time from when the laser pulse generated based on the reference signal is emitted to when the calculated value of the cross-correlation function is maximum as the ToF. Alternatively, the processor 120 may determine the time from when the laser pulse generated based on the reference signal is emitted to when the calculated value of the cross-correlation function exceeds a preset threshold as the ToF.

[0044] Processor 120 may calculate the distance to the object by using the ToF and velocity of the laser pulses.

[0045] Figure 2 is a block diagram of an example of the antenna unit 200 according to an embodiment.

[0046] The antenna unit 200 may include a transmitter 210 and a receiver 220 .

[0047] Emitter 210 may include a light source for generating laser pulses. For example, the light source may include a device for generating light in the infrared range. When using light in the infrared range, it is possible to prevent it from mixing with natural light in the visible range, including sunlight. However, the present disclosure is not limited thereto, and emitter 210 may include a light source for generating light in various wavelength ranges, and may generate multiple lights in different wavelength ranges.

[0048] The emitter 210 may include a light source such as a laser diode (LD), an edge-emitting laser, a vertical cavity surface-emitting laser (VCSEL), a distributed feedback laser, a light-emitting diode (LED), and a superluminescent diode (SLD). However, the present disclosure is not limited thereto.

[0049] In an embodiment, emitter 210 may emit laser pulses generated based on a reference signal. The reference signal may determine the characteristics of the laser pulses. For example, the laser pulses may have an intensity corresponding to the value of the reference signal or a frequency corresponding to the frequency of the reference signal. LiDAR device 100 may change the characteristics of the laser pulses emitted by emitter 210 by adjusting the characteristics of the reference signal. The laser pulses emitted by emitter 210 may be reflected after striking an object.

[0050] The receiver 220 may include a plurality of sensors for sensing laser pulses. The receiver 220 may obtain a received signal from the received laser pulse. For example, the receiver 220 may further include a photodetector for converting the received laser pulse into an electrical signal, and the electrical signal output by the photodetector may correspond to the received signal. For example, the photodetector may include at least one of an avalanche photodiode (APD) or a single photo avalanche diode (SPAD), but the present disclosure is not limited thereto.

[0051] Figure 3 is a block diagram of an example of a transmitter 300 according to an embodiment.

[0052] The transmitter 300 can transmit the laser pulse by steering the laser pulse mechanically or non-mechanically. For example, the transmitter 300 can transmit the laser pulse by steering the laser pulse using a micro-electromechanical system (MEMS), a rotary motor, a mirror, or a lens.

[0053] In an embodiment, the transmitter 300 may manipulate the scanning angle of the laser pulse by using an optical phased array (OPA) in a non-mechanical method. In an embodiment, the transmitter 300 may include a light source 310 , a separator 320 , a phase shifter 330 , and an antenna array 340 .

[0054] The light source 310 may generate laser pulses. The light source 310 may include an LD, a laser, an LED, and an SLD, but the present disclosure is not limited thereto. In addition, the light source 310 may include an optically pumped laser, a solid-state laser, a liquid laser, a gas laser, a semiconductor laser, a chemical laser, and a pulsed laser, but the present disclosure is not limited to the listed types.

[0055] The splitter 320 may include an optical branching element that splits an input laser pulse into multiple laser pulses and outputs the split laser pulses. The splitter 320 may evenly split the input laser pulses and output the evenly split laser pulses. For example, the splitter 320 may be formed on a bulk silicon substrate.

[0056] The phase shifter 330 can change the phase of the input laser pulse and output a laser pulse with the changed phase. For example, the phase shifter 330 can change the phase of the laser pulse passing through the waveguide by applying any one of heat, light, current, voltage, and pressure to the waveguide. For example, the phase shifter 330 can be formed on a semiconductor substrate. For example, the phase shifter 330 can include a resistive heater, a PIN diode phase shifter, a PN diode phase shifter, and a silicon-on-insulator capacitor (SISCAP) phase shifter, but the present disclosure is not limited thereto.

[0057] As the phase shifter 330 changes the phase of the laser pulse, the laser pulse emitted by the antenna array 340 can be steered. In other words, by controlling the phase shifter 330, the scanning angle of the laser pulse emitted by the transmitter 300 can be steered.

[0058] The antenna array 340 may include discrete antenna elements. The antenna elements may include horns, dipoles, and microstrip patches, but the present disclosure is not limited thereto. The antenna elements may correspond to individual channels and may be connected to the output of the phase shifter 330. In this state, the channel may represent the path that the laser pulse passes through.

[0059] Figure 4 An example of a radiation pattern of the LiDAR device 400 according to an embodiment is shown.

[0060] When the LiDAR device 400 is controlled to emit laser pulses at a desired scanning angle, laser pulses with higher intensity are emitted from the antenna array at the scanning angle, which can generate a main lobe 410 at the scanning angle. Ideally, only the main lobe 410 will be generated. However, in actual operation, side lobes 420 are generated at angles different from the scanning angle.

[0061] The main lobe 410 may represent laser pulses emitted at a desired angle, and the side lobes 420 may represent laser pulses emitted at an undesired angle. In other words, the main lobe 410 may represent laser pulses emitted at a scan angle, and the side lobes 420 may represent laser pulses emitted at angles other than the scan angle. Figure 4 One main lobe is shown as the main lobe 410 and two side lobes are shown as the side lobes 420, but various angles and intensities of the side lobes 420 may be generated. For example, the side lobes 420 may include grating lobes having the same intensity as that of the main lobe 410.

[0062] When the spacing between antenna elements of the antenna array is less than or equal to half the wavelength of the laser pulse, the generation of side lobes 420 can be limited. However, as the spacing between antenna elements decreases, thermal coupling between the antenna elements may become severe. In addition, since a large number of antenna elements are required to reduce the divergence angle of the laser pulse, it may be difficult to arrange a large number of antenna elements at a spacing less than or equal to half the wavelength of the laser pulse.

[0063] Figure 5 An example of measuring a distance by the LiDAR apparatus 500 according to an embodiment is shown.

[0064] When the LiDAR device 500 emits a laser pulse at a scanning angle θ1, a main lobe 510 may be generated at the scanning angle θ1, and a side lobe 520 may be generated at an angle θ2. When objects A and B are located at θ1 and θ2, respectively, the LiDAR device 500 may receive not only the laser pulse formed when the main lobe 510 is reflected from object A, but also the laser pulse formed when the side lobe 520 is reflected from object B. In other words, when the received laser pulse is affected by the side lobe 520, the side lobe 520 may distort the distance measurement at the scanning angle θ1. For example, although object A is actually separated by a distance D1, due to the distortion caused by the side lobe 520, object A may be measured as being located at a distance D2.

[0065] As mentioned above Figure 4 As described above, it is difficult to control the generation of side lobes by changing the structure of the antenna array. Therefore, in order to accurately measure the distance, a method for correcting the distortion caused by the side lobes is needed.

[0066] In the following description, by using the embodiment of the present invention, Figure 1 The LiDAR device 100 includes an antenna unit 110 and a processor 120 to measure distance.

[0067] Figure 6 An example of a method of obtaining an angle at which a side lobe is generated according to an embodiment is shown.

[0068] The radiation pattern of the antenna unit 110 may be measured. The radiation pattern may be measured before or after the antenna unit 110 is mounted on the LiDAR device 100. The radiation pattern may be measured by an external measurement device such as a photodetector, a thermal imaging camera, or an IR camera.

[0069] The external measurement device or processor 120 can obtain a beam profile based on the measured radiation pattern, where the beam profile indicates the intensity of the laser pulse relative to the scanning angle. In addition, the external measurement device or processor 120 can obtain the angle at which the side lobe is generated relative to the main lobe, the main lobe intensity, the side lobe intensity, and the ratio of the side lobe intensity to the main lobe intensity from the obtained beam profile.

[0070] For example, from Figure 6 The beam profile can obtain the angle of side lobe generation relative to the main lobe (i.e., angles -30° and 30°), the side lobe intensity (i.e., 40 a.u. (arbitrary unit)), the main lobe intensity (i.e., 80 a.u.), and the ratio of the side lobe intensity to the main lobe intensity (i.e., 0.5).

[0071] Figure 7 An example of a method of operating a LiDAR device according to an embodiment is shown.

[0072] exist Figure 7 , the footprint of the laser pulses emitted by the transmitter of the antenna unit 110 is shown relative to the field of view of the LiDAR device 100. The footprint may be caused by the divergence angle p of the laser pulses.

[0073] The transmitter of the antenna unit 110 may emit laser pulses by changing a scanning angle θ in the horizontal direction. In this state, the scanning angle θ may represent an angle at which the laser pulses are emitted in the horizontal direction relative to the field of view of the LiDAR device 100. Figure 7 The scanning angles θ1...θ N The footprint of the emitted laser pulse.

[0074] The transmitter can emit laser pulses by changing the scanning angle θ in the horizontal direction for each row. For example, when the emission of the laser pulse for row 1 is completed, the transmitter can emit laser pulses by changing the scanning angle θ in the horizontal direction for row 2, and finally emit laser pulses in the horizontal direction for row M.

[0075] The transmitter can change the scanning angle θ of the laser pulse by using a phase shifter. The transmitter can also change the line of the irradiated laser pulse by changing the wavelength of the laser pulse.

[0076] Alternatively, the transmitter may transmit laser pulses by changing the scanning angle in the vertical direction.

[0077] based on Figure 7 Set the horizontal direction and vertical direction. The horizontal direction and vertical direction can represent any two directions that are orthogonal to each other.

[0078] Alternatively, the transmitter may emit laser pulses by changing the scanning angle in various directions. For example, when the transmitter emits laser pulses by changing the scanning angle in the circumferential direction, the coverage area may form a concentric circle shape.

[0079] The receiver of the antenna unit 110 can obtain a received signal by converting the received laser pulse. For example, the receiver can obtain the received signal from the laser pulse by using an analog-to-digital (AD) converter. The value of the received signal can represent the intensity of the received laser pulse.

[0080] The receiver can obtain a received signal corresponding to the scanning angle θ by changing the received laser pulse. For example, the receiver can obtain a received signal corresponding to the scanning angle θ1 of row 1, a received signal corresponding to the scanning angle θ2 of row 1, and finally a received signal corresponding to the scanning angle θ N The corresponding received signal.

[0081] Processor 120 can correct the effects of sidelobes in the received signal. Processor 120 can correct the received signal for each row. For example, processor 120 can receive all received signals corresponding to row 1 and correct the obtained received signal, receive all received signals corresponding to row 2 and correct the obtained received signal, and finally receive all received signals corresponding to row M and correct the obtained received signal. The processor can obtain the ToF of the laser pulse by using the correlation between the corrected received signals and a reference signal.

[0082] Figure 8 An example of a method of correcting a received signal according to an embodiment is shown.

[0083] Figure 8 An example in which the processor 120 corrects the received signal corresponding to any one row is shown. For example, the processor 120 may correct the received signal corresponding to any one row. Figure 7 The scanning angles θ1...θ in row 1 N The corresponding received signal.

[0084] The processor 120 can compare the scanning angles θ1 ...θ N The corresponding receiving signal RX1...RX N The value of the received signal can represent the intensity of the received laser pulse.

[0085] The processor 120 may compare the received signals RX1 . . . RX 1 with respect to time. NThe processor 120 may cause the received signals RX1 . . . RX N Synchronize to compare the received signal RX1...RX N In the embodiment, since the receiving signals RX1 . . . RX N are obtained from the received laser pulses at different points in time, so it may be necessary to synchronize the time to compare the received signals RX1...RX N For example, the receiving signal RX1...RX N Synchronize so that the time points at which the laser pulses are emitted are the same.

[0086] The processor 120 compares the received signals RX1 . . . RX with respect to time. N , which can be compared with the received signal RX1...RX with respect to the distance N This is because the ToF of the laser pulse indicates the distance between the LiDAR device and the object.

[0087] The processor 120 can correct the received signal by using the angle at which the side lobe is generated relative to the main lobe of the laser pulse emitted by the LiDAR device 100. The processor 120 can correct the value of the sub-received signal corresponding to the scanning angle at a time point, which is deviated from the scanning angle corresponding to the main received signal by the angle at which the side lobe is generated. The angle at which the side lobe is generated relative to the main lobe can be obtained in advance. The processor 120 can correct the value of the sub-received signal at this time point by using a correction factor, which is the ratio of the side lobe intensity to the main lobe intensity of the LiDAR device. The processor 120 can subtract the value obtained by multiplying the correction factor by the value of the main received signal from the value of the sub-received signal. The processor 120 can correct the value of the sub-received signal based on the following mathematical expression 2.

[0088] [Mathematical expression 2]

[0089] I sub_new (t1)=I sub_old (t1)-I main (t1)*(B / A)

[0090] In mathematical expression 2, t1 represents a certain time point, I sub_old (t1) represents the value of the sub-received signal before correction at the time point t1, I main (t1) represents the value of the main received signal at time point t1, A represents the main lobe intensity, B represents the side lobe intensity, I sub_new ( t1 ) represents the value of the sub-reception signal after correction at the time point t1 .

[0091] When the value of the sub-received signal at that time point is less than a predetermined value, the processor 120 may not correct the value of the sub-received signal. The predetermined value may be a value used to distinguish meaningful received signals. The value of the sub-received signal at that time point being less than the predetermined value may indicate that there is no object to be corrected.

[0092] For example, the processor 120 may receive signals RX1 . . . RX N The main reception signal RX2 having the maximum value at the time point t1 is identified. When the scanning angle θ2 of the main reception signal RX2 deviates from the scanning angle of the angle generating the side lobe, the scanning angle is θ 14 When the processor 120 can correct the time point t1 and the scanning angle θ 14 The corresponding sub-received signal RX 14 The value of .

[0093] For example, the processor 120 may receive signals RX1 . . . RX N Identify the main received signal RX with the maximum value at time point t2 14 When the master receives the signal RX 14 The scanning angle θ 14 When the scanning angle that deviates from the angle at which the side lobe is generated is θ2, the processor 120 may correct the value of the sub-received signal RX2 corresponding to the scanning angle θ2 at time point t2. Alternatively, when the processor 120 determines that the value of the sub-received signal RX2 at time point t2 is less than a predetermined value, the processor 120 may not correct the value of the sub-received signal RX2 at time point t2.

[0094] For example, the processor 120 may receive signals RX1 . . . RX N Identify the main received signal RX with the maximum value at time point t3 13 When the master receives the signal RX 13 The scanning angle θ 13 When the scanning angle deviated from the angle at which the side lobe is generated is θ1, the processor 120 may correct the value of the sub-reception signal RX1 corresponding to the scanning angle θ1 at the time point t3.

[0095] Figure 9 Another example of the method of correcting a reception signal according to the embodiment is shown.

[0096] The processor 120 may identify a plurality of primary received signals in the received signal relative to time, each primary received signal having a maximum value. In some cases, a plurality of primary received signals may be identified, each having a maximum value.

[0097] The processor 120 may determine whether a difference between a plurality of scanning angles corresponding to the main reception signal matches an angle at which a side lobe is generated with respect to the main lobe.

[0098] The matching of the difference between the scanning angles and the angle generating the sidelobe can indicate that the main received signals are influencing each other. Therefore, when the processor 120 determines that the difference between the scanning angles matches the angle generating the sidelobe, the processor 120 can correct each main received signal. In detail, the processor 120 can subtract a value from the value of any main received signal, which is obtained by multiplying the value of the other main received signal by the ratio of the sidelobe intensity to the mainlobe intensity of the LiDAR device. In detail, the processor 120 can correct the value of the main received signal based on the following mathematical expression 3.

[0099] [Mathematical expression 3]

[0100] I main1_new (t1)=I main1_old (t1)-I main2_o1d (t1)*(B / A)

[0101] In mathematical expression 3, t1 represents a certain time point, I main1_old (t1) represents the value of any main received signal before correction at time point t1, I main2_old (t1) represents the value of another main received signal before correction at the time point t1, A represents the main lobe intensity, B represents the sublobe intensity, and I main1_new ( t1 ) represents the value of any main received signal after correction at time point t1 .

[0102] The difference between the scanning angles does not match the angle generating the side lobe, which may indicate that the main reception signals do not affect each other. Therefore, when the processor 120 determines that the difference between the scanning angles does not match the angle generating the side lobe, the processor 120 may not correct the main reception signal.

[0103] For example, the processor 120 may identify the respective maximum values ​​P at time t1. max The processor 120 may determine whether the difference between the scanning angle θ1 corresponding to the first main received signal RX1 and the scanning angle θ2 corresponding to the second main received signal RX2 matches the angle at which the side lobe is generated relative to the main lobe. When the processor 120 determines that the difference between the scanning angle θ1 corresponding to the first main received signal RX1 and the scanning angle θ2 corresponding to the second main received signal RX2 matches the angle at which the side lobe is generated, the processor 120 may correct the value of each of the first main received signal RX1 and the second main received signal RX2 at the time point t1 to P max -P maxAlternatively, when the processor 120 determines that the difference between the scanning angle θ1 corresponding to the first main received signal RX1 and the scanning angle θ2 corresponding to the second main received signal RX2 does not match the angle at which the side lobe is generated, the processor 120 may not correct the values ​​of the first main received signal RX1 and the second main received signal RX2 at the time point t1.

[0104] Figure 10 An example of a method of obtaining ToF according to an embodiment is shown.

[0105] The processor 120 can calculate the distance to the object by using the ToF and speed of the laser pulse. In an embodiment, the processor 120 can calculate the distance to the object by using the corrected received signal R x The processor 120 can calculate the ToF of the laser pulse from the time point when the cross-correlation function CR between the corrected received signal Rx and the reference signal Tx is maximum.

[0106] For example, when the received signal Rx has a larger value at time point t1 than time point t2, t1 can be obtained from the cross-correlation function CR, and ToF can be obtained from the difference between t0 and t1. In this state, t0 can be the time point when the laser pulse generated from the reference signal is emitted.

[0107] Figure 11 is a flow chart of a method of operating a LiDAR device according to an embodiment. Figure 11 , the method of operating the LiDAR device is to Figure 1 An algorithm for time-serial processing in the LiDAR device 100 .

[0108] In operation 1101, the processor 120 may obtain a received signal corresponding to a laser pulse generated from a reference signal. The antenna unit 110 may convert the reference signal generated by the processor 120 and transmit a laser pulse, and receive the reflected laser pulse. The antenna unit 110 may change the scanning angle along a direction within the field of view of the LiDAR device 100 and transmit the laser pulse. The processor 120 may store the obtained received signal in a memory.

[0109] In operation 1102, the processor 120 may obtain a main received signal having a maximum value at a certain time point from the received signal. The processor 120 may read the received signal stored in the memory and then compare the values ​​of the received signals. The processor 120 may synchronize the received signals and then compare the values ​​of the received signals at each time point.

[0110] In operation 1103, the processor 120 may use the maximum value to correct the value of the sub-received signal included in the received signal at a certain point in time. The processor 120 may correct the value of the sub-received signal corresponding to a scanning angle that deviates from the scanning angle of the main received signal by an angle that generates a side lobe relative to the main lobe. The processor 120 may correct the value of the sub-received signal at a certain point in time by subtracting from the value of the sub-received signal at the certain point in time a value obtained by multiplying the value of the main received signal at the certain point in time by the ratio of the side lobe intensity to the main lobe intensity.

[0111] In operation 1104, the processor 120 may obtain the ToF of the laser pulse corresponding to the sub-received signal by using the correlation between the corrected sub-received signal and the reference signal. The processor 120 may calculate the ToF of the laser pulse corresponding to the sub-received signal from the time point when the value of the cross-correlation function between the corrected sub-received signal and the reference signal is maximum.

[0112] Figure 12 Included are diagrams for describing an experiment of measuring a distance by using a LiDAR device according to an embodiment.

[0113] In the experiment, the frequency and pulse width of the laser pulse emitted by the transmitter of the antenna unit 110 were set to 1 MHz and 10 ns, respectively. In addition, when the transmitter was turned on, the transmitter of the antenna unit 110 was set to emit laser pulses with an intensity of 100 a.u. When the transmitter was turned off, the transmitter of the antenna unit 110 was set to emit laser pulses with an intensity of 0 a.u. In addition, the sampling rate of the receiver of the antenna unit 110 was set to 1 GHz. In addition, the field of view of the LiDAR device 100 was set to -45° to 45°, the angles at which side lobes were generated were set to -30° and 30° relative to the main lobe, the main lobe intensity was set to 80 a.u., the side lobe intensity was set to 40 a.u., the correction factor which is the ratio of the side lobe intensity to the main lobe intensity was set to 0.5, and the divergence angle was set to 0.5°.

[0114] Experiments were conducted on two scenarios. In the first scenario, it was assumed that object A was located at a distance of 90 meters and had an angle of 0° relative to the field of view of the LiDAR device 100, and object B was located at a distance of 40 meters and had an angle of -30°. In the second scenario, it was assumed that object A was located at a distance of 90 meters and had an angle of 0° relative to the field of view of the LiDAR device 100, object B was located at a distance of 40 meters and had an angle of -30°, and object C was located at a distance of 25 meters and had an angle of -30°.

[0115] Figure 13 Experimental results according to the first scenario according to an embodiment are shown.

[0116] According to the experimental results, a reception signal RX1 ( t ) corresponding to a scanning angle of −30°, a reception signal RX2 ( t ) corresponding to a scanning angle of 0°, and a reception signal RX3 ( t ) corresponding to a scanning angle of 30° were obtained.

[0117] RX1(t1), which is the value of the received signal RX1(t) relative to t1, is approximately 100 a.u., RX2(t1), which is the value of the received signal RX2(t), relative to t1, is approximately 40 a.u., and RX3(t1), which is the value of the received signal RX3(t), relative to t1, is approximately 0 a.u. RX1(t2), which is the value of the received signal RX1(t) relative to t2, is approximately 10 a.u., RX2(t2), which is the value of the received signal RX2(t), relative to t2, is approximately 20 a.u., and RX3(t2), which is the value of the received signal RX3(t), relative to t2, is approximately 10 a.u.

[0118] The processor 120 corrects the received signals RX1(t), RX2(t), and RX3(t), thereby obtaining corrected received signals RX1'(t), RX2'(t), and RX3'(t).

[0119] Processor 120 obtains the primary received signal having the maximum value among received signals RX1(t), RX2(t), and RX3(t) at time t1. According to experimental results, since RX1(t1) has a maximum value of approximately 100 a.u., RX1(t) is obtained as the primary received signal.

[0120] Processor 120 corrects the sub-received signal. The sub-received signal to be corrected includes a received signal RX2(t) corresponding to an angle of 0°, which is an angle deviated by 30° from a scanning angle of -30° corresponding to the main received signal RX1(t). The angle 30° is an angle at which side lobes are generated.

[0121] Processor 120 removes the value obtained by multiplying RX1(t1) by the correction factor from RX2(t1). Since RX2(t1) is approximately 40 a.u., RX1(t1) is approximately 100 a.u., and the correction factor is 0.5, the value of RX2′(t1) is -10 a.u., which is the result of the expression 40-100*0.5. Alternatively, when RX2′(t1) has a negative value, processor 120 may convert the value to 0.

[0122] Processor 120 obtains the primary received signal having the maximum value among received signals RX1(t), RX2(t), and RX2(t) at time t2. According to experimental results, since RX2(t2) has a maximum value of approximately 20 a.u., RX2(t) is obtained as the primary received signal.

[0123] Processor 120 corrects the sub-received signals. The sub-received signals to be corrected include received signals RX1(t) and RX3(t) corresponding to angles of -30° and 30°, respectively. The angles -30° and 30° are angles that deviate from a scanning angle of 0° corresponding to the main received signal RX2(t) by -30° and 30°, respectively. The angles -30° and 30° are angles that generate side lobes.

[0124] The processor 120 removes the value obtained by multiplying RX2(t2) by the correction factor from RX1(t2). Since RX1(t2) is approximately 10 a.u., RX2(t2) is approximately 20 a.u., and the correction factor is 0.5, the value of RX1′(t2) may be 0 a.u., which is the result of the expression 10-20*0.5.

[0125] The processor 120 removes the value obtained by multiplying RX2(t2) by the correction factor from RX3(t2). Since RX3(t2) is approximately 10 a.u., RX2(t2) is approximately 20 a.u., and the correction factor is 0.5, the value of RX3′(t2) may be 0 a.u., which is the result of the expression 10-20*0.5.

[0126] When processor 120 uses pre-corrected received signals RX1(t), RX2(t), and RX3(t) to measure distance, object B is located at a distance of approximately 40 meters and at an angle of -30°, object A is located at a distance of approximately 40 meters and at an angle of 0°, and object C is located at a distance of approximately 90 meters and at an angle of 30°. In the first scenario, since object A is located at 90 meters and at 0°, and object C is absent, an erroneous result is obtained. This is because when measuring distance at a scanning angle of 0°, the sidelobes generated at an angle of -30° are reflected by object B, causing distortion in the received laser pulse.

[0127] When processor 120 uses the corrected received signals RX1′(t), RX2′(t), and RX3′(t) to measure the distance, object B is located at approximately 40 meters and -30 degrees, and object A is located at approximately 90 meters and 0 degrees. As a result of matching the first scenario, it can be seen that the distortion in the distance measurement caused by the side lobes can be corrected.

[0128] Figure 14 Experimental results according to the second scenario according to the embodiment are shown.

[0129] According to the experimental results, a reception signal RX1 ( t ) corresponding to a scanning angle of −30°, a reception signal RX2 ( t ) corresponding to a scanning angle of 0°, and a reception signal RX3 ( t ) corresponding to a scanning angle of 30° were obtained.

[0130] RX1(t1) is approximately 0 a.u., RX2(t1) is approximately 50 a.u., and RX3(t1) is approximately 150 a.u. RX1(t2) is approximately 100 a.u., RX2(t2) is approximately 40 a.u., and RX3(t2) is approximately 0 a.u. RX1(t3) is approximately 10 a.u., RX2(t3) is approximately 20 a.u., and RX3(t3) is approximately 10 a.u.

[0131] Since the processor 120 corrects the received signals RX1(t), RX2(t), and RX3(t), corrected received signals RX1'(t), RX2'(t), and RX3'(t) are obtained.

[0132] Processor 120 obtains the primary received signal having the maximum value among received signals RX1(t), RX(t), and RX3(t) relative to time point t1. According to experimental results, since RX3(t1) has a maximum value of approximately 150 a.u., RX3(t) is obtained as the primary received signal.

[0133] The processor 120 corrects the sub-received signal. The sub-received signal to be corrected is the received signal RX2(t) corresponding to 0°, which is an angle deviated by -30° from the scanning angle 30° corresponding to the main received signal RX3(t). -30° is an angle that generates side lobes.

[0134] The processor 120 removes the value obtained by multiplying RX3(t1) by the correction factor from RX2(t1). Since RX2(t1) is approximately 40 a.u., RX3(t1) is approximately 150 a.u., and the correction factor is 0.5, the value of RX2′(t1) may be -35 a.u., which is the result of the expression 40-150*0.5. Alternatively, when RX2′(t1) has a negative value, the processor 120 may convert the value to 0.

[0135] Likewise, the processor 120 corrects the received signal with respect to time points t2 and t3.

[0136] When processor 120 measures distance using pre-corrected received signals RX1(t), RX2(t), and RX3(t), object B is located at approximately 40 meters and -30 degrees, object A is located at approximately 25 meters and 0 degrees, and object C is located at approximately 25 meters and 30 degrees. In the second scenario, an erroneous result is obtained because object A is located at 90 meters and 0 degrees. This is because when measuring distance at a scanning angle of 0 degrees, distortion occurs due to the laser pulses received due to reflections from the sidelobes generated at -30 degrees from object B and the laser pulses received due to reflections from the sidelobes generated at 30 degrees from object C.

[0137] When processor 120 uses the corrected received signals RX1′(t), RX2′(t), and RX3′(t) to measure the distance, object B is located at approximately 40 meters and -30 degrees, object A is located at approximately 90 meters and 0 degrees, and object C is located at approximately 25 meters and 30 degrees. As a result of matching the second scenario, it can be seen that the distortion in the distance measurement caused by the side lobes can be corrected.

[0138] Figure 15 A vehicle including a LiDAR device is shown according to an example embodiment.

[0139] like Figure 15 As shown, the host vehicle 1000 may include a LiDAR device 100. The LiDAR device 100 may emit light toward the neighboring vehicle 2000, detect the light when the light is reflected back from the neighboring vehicle 2000, and determine the distance between the host vehicle 1000 and the neighboring vehicle 2000 based on the emitted light and the detected light, as shown in FIG. Figure 1 The host vehicle 1000 may control the operation (eg, speed, direction, etc.) of the host vehicle 1000 based on the distance to the neighboring vehicle 2000 determined by the LiDAR device 100 .

[0140] Although Figure 15 The LiDAR device 100 is shown as being installed in a vehicle, but example embodiments are not limited thereto. For example, the LiDAR device 100 may be included in an airplane, a mobile robot configured to build a map based on the distances between the mobile robot and nearby objects, a robot cleaner configured to move by avoiding collisions with nearby obstacles based on distance information between the robot cleaner and nearby obstacles, or a smartphone or notebook computer configured to generate and display distance information to one or more target objects.

[0141] Although not limited thereto, the example embodiments may be embodied as computer-readable code on a computer-readable recording medium. The computer-readable recording medium is any data storage device that can store data that can be subsequently read by a computer system. Examples of computer-readable recording media include read-only memory (ROM), random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage devices. The computer-readable recording medium may also be distributed on a network-coupled computer system, thereby storing and executing the computer-readable code in a distributed manner. Moreover, the example embodiments may be written as a computer program transmitted on a computer-readable transmission medium such as a carrier wave, and received and implemented in a general-purpose or special-purpose digital computer that executes the program. Furthermore, it should be understood that in the example embodiments, one or more units of the above-mentioned apparatus and devices may include circuits, processors, microprocessors, etc., and may execute a computer program stored in a computer-readable medium.

[0142] The foregoing exemplary embodiments are merely exemplary and should not be construed as limiting. The present teachings can be readily applied to other types of devices. Moreover, the description of the exemplary embodiments is intended to be illustrative, not limiting, of the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.

[0143] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. The description of features or aspects in each embodiment should generally be considered applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, it should be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the appended claims.

Claims

1. A method of operating a light detection and ranging (LiDAR) device, the method comprising: obtaining a received signal corresponding to a laser pulse generated from a reference signal; Obtaining a main received signal having a maximum value relative to any time point among the received signals; correcting a value of a sub-reception signal at the time point by using the maximum value, wherein the sub-reception signal includes a reception signal corresponding to a scanning angle that deviates from a scanning angle of the LiDAR device corresponding to the main reception signal by an angle that generates a side lobe of a laser pulse emitted by the LiDAR device; as well as The time of flight ToF of the laser pulse corresponding to the sub-received signal is obtained by using the correlation between the corrected sub-received signal and the reference signal.

2. The method according to claim 1, wherein Correcting the value of the sub-received signal includes subtracting a value obtained by multiplying the maximum value by a correction factor from the value of the sub-received signal at the time point.

3. The method according to claim 1, wherein Correcting the value of the sub-reception signal includes correcting the value of the sub-reception signal at the time point by using a correction factor, the correction factor being a ratio of an intensity of a side lobe to an intensity of a main lobe of a laser pulse emitted by the LiDAR device.

4. The method according to claim 1, wherein Correcting the value of the sub-reception signal includes correcting the value of the sub-reception signal at the time point by using the angle at which the side lobe is generated relative to a main lobe of a laser pulse emitted by the LiDAR device.

5. The method according to claim 1, wherein Obtaining the primary received signal includes: synchronizing the received signal; and The received signals are compared over time.

6. The method according to claim 1, wherein Obtaining the received signal includes: emitting a laser pulse generated from the reference signal for each scan angle in a direction in a field of view of the LiDAR device; and A reception signal corresponding to a laser pulse generated from the reference signal is obtained for each of the scanning angles, and the obtained reception signal is stored in a memory.

7. The method according to claim 1, wherein Obtaining the primary received signal includes: calculating a cross-correlation function between the sub-received signal and the reference signal; determining a point in time at which the value of the calculated cross-correlation function has the maximum value; and The time from the time point of the laser pulse corresponding to the sub-reception signal to the time point at which the calculated value of the cross-correlation function has the maximum value is determined as the ToF.

8. The method according to claim 1, wherein Obtaining the primary received signal includes: relative to any time point, obtaining a first main received signal and a second main received signal, each having the maximum value, in the received signals; The correcting the value of the sub-received signal includes: Obtaining a first scanning angle and a second scanning angle, where the first scanning angle and the second scanning angle are scanning angles corresponding to the first main received signal and the second main received signal; determining whether a difference between the first scanning angle and the second scanning angle matches an angle that produces a side lobe relative to a field of view of the LiDAR device; When it is determined that the difference between the first scanning angle and the second scanning angle matches the angle at which the side lobe is generated, correcting the value of the first main received signal at the time point and the value of the second main received signal at the time point; and When it is determined that the difference between the first scanning angle and the second scanning angle does not match the angle generating the side lobe, the value of the first main reception signal at the time point and the value of the second main reception signal at the time point are not corrected. 9 . A non-transitory computer-readable recording medium having recorded thereon a program for executing the method according to claim 1 .

10. A light detection and ranging (LiDAR) device comprising: an antenna unit configured to transmit and receive laser pulses; as well as The processor is configured to: obtain a received signal corresponding to the laser pulse generated from the reference signal, obtaining a main received signal having a maximum value relative to any time point among the received signals, correcting a value of a sub-reception signal at the time point by using the maximum value, wherein the sub-reception signal includes a reception signal corresponding to a scanning angle that deviates from a scanning angle of the LiDAR device corresponding to the main reception signal by an angle that generates a side lobe of a laser pulse emitted by the LiDAR device, and The time of flight ToF of the laser pulse corresponding to the sub-received signal is obtained by using the correlation between the corrected sub-received signal and the reference signal.

11. The LiDAR device according to claim 10, wherein: The processor corrects the value of the sub-reception signal by subtracting a value obtained by multiplying the maximum value by a correction factor from the value of the sub-reception signal at the time point.

12. The LiDAR device according to claim 10, wherein: The processor corrects the value of the sub-reception signal at the time point by using a correction factor, the correction factor being a ratio of an intensity of a side lobe to an intensity of a main lobe of a laser pulse emitted by the LiDAR device.

13. The LiDAR device according to claim 10, wherein: The processor corrects the value of the sub-reception signal at the time point by using the angle at which the side lobe is generated with respect to a main lobe of a laser pulse emitted by the LiDAR device.

14. The LiDAR device according to claim 10, wherein: The processor synchronizes the received signals and compares the received signals in time.

15. The LiDAR device according to claim 10, further comprising a memory, in, The processor is further configured to: emitting a laser pulse generated from the reference signal for each scan angle along a direction in the field of view of the LiDAR device; as well as A reception signal corresponding to the laser pulse generated from the reference signal is obtained for each of the scanning angles, and the obtained reception signal is stored in the memory.

16. The LiDAR device according to claim 10, wherein: The processor calculates a cross-correlation function between the sub-reception signal and the reference signal, determines a time point at which the value of the calculated cross-correlation function has the maximum value, and determines a time between a time point of a laser pulse corresponding to the sub-reception signal and a time point at which the value of the calculated cross-correlation function has the maximum value as the ToF.

17. The LiDAR device according to claim 10, wherein: The processor is further configured to: With respect to any time point, obtaining a first main received signal and a second main received signal, each having the maximum value, in the received signals; Obtaining a first scanning angle and a second scanning angle, where the first scanning angle and the second scanning angle are scanning angles corresponding to the first main received signal and the second main received signal; determining whether a difference between the first scanning angle and the second scanning angle matches an angle that produces a side lobe relative to a field of view of the LiDAR device; When it is determined that the difference between the first scanning angle and the second scanning angle matches the angle at which the side lobe is generated, correcting the value of the first main received signal at the time point and the value of the second main received signal at the time point; as well as When it is determined that the difference between the first scanning angle and the second scanning angle does not match the angle generating the side lobe, the value of the first main reception signal at the time point and the value of the second main reception signal at the time point are not corrected.

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