Laser radar control method and laser radar

Abstract

The present invention provides a laser radar control method, comprising: S101: emitting a laser pulse signal based on a pulse code and a current energy allocation strategy, wherein the laser pulse signal includes multiple laser pulses using the pulse code for detecting a target; S102: receiving echo information from the multiple laser pulses reflected by the target; and S103: updating the energy allocation strategy used by the laser radar for the next transmission based on the echo information from the target. Preferred embodiments of the present invention address both short-range anti-crosstalk requirements and long-range detection accuracy and performance, achieving maximum efficiency in the application of laser pulse energy while meeting eye safety requirements.

Description

Technical Field

[0001] The present invention generally relates to the field of laser detection technology, and in particular to a control method for a laser radar and a laser radar. Background Art

[0002] LiDAR is usually used for ranging based on the direct time-of-flight method (TOF), that is, by emitting narrow but high-peak-power laser pulses and measuring the flight time of the laser pulses between the LiDAR and the target to measure the distance.

[0003] When multiple LiDARs are operating simultaneously within the same measurement range—for example, when multiple LiDARs are installed on a single vehicle, or when multiple LiDAR-equipped vehicles are located close together—because LiDAR's measurement principle is based on measuring the time-of-flight of transmitted laser pulses, if each LiDAR cannot distinguish whether a received echo pulse is its own, then there is a certain probability that an echo pulse received from another LiDAR will also be identified as an echo signal, resulting in erroneous ranging results, or crosstalk. When multiple LiDARs are operating simultaneously, the problem of mutual interference between different LiDARs has become a bottleneck restricting their development.

[0004] Currently, the use of multi-pulse coding to identify echo signals is an effective anti-interference solution for lidar. However, the use of pulse coding will affect the range-finding performance of lidar.

[0005] This is because the energy of each laser radar pulse is limited by the eye safety requirements. In other words, the energy of each pulse cannot be increased indefinitely and must be below the eye safety threshold.

[0006] For example, in my country, according to the "User Guide to Part 14 of the National Standard of the People's Republic of China on Laser Product Safety", lasers are divided into four categories: Category 1: Laser products whose laser radiation shall not exceed the threshold of Category 1 within the corresponding wavelength and emission duration; Category 1M: Laser products whose wavelength is in the range of 0.3-4μm, whose energy threshold shall not exceed Category 1 and which use a smaller measurement aperture; Category 2: Laser products whose laser radiation shall not exceed the threshold of Category 2 within the corresponding wavelength and emission duration; Category 2M: Laser products whose wavelength is in the range of 0.7-1.4μm, whose energy threshold shall not exceed Category 2 and which use a smaller measurement aperture or are evaluated at a farther distance from the performance light; Categories 3R and 3B: Light-adding products that are allowed to exceed the energy thresholds of Categories 1 and 2 within any wavelength range, but shall not exceed the respective energy thresholds of 3R and 3B; Category 4: Laser products to which personnel may be exposed that may exceed the achievable emission limit of Category 3B.

[0007] In actual application, if the laser is directly irradiated, it will cause damage to the human eye, so there are strict requirements for the selection of lasers. Usually, the wavelength of the laser is set between 0.7-1.4μm. According to the classification of the "Guidelines", the maximum limit of naked eye safety is 3R. Taking the wavelength of 905nm as an example, assuming that the irradiation duration t is equal to 10s and the pulse repetition frequency f is 8.8kHz, the number of pulses N within this time is 8×104, and the maximum allowable corneal irradiation MPEMAX is 2601.4J / m2. According to the formula: MPE average =MPE max / N, the calculated single pulse irradiation dose MPEAVERAGE is 0.033J / m2. If continuous pulses are used, the continuous pulse MPETRAIN is 1.962μJ / m2.

[0008] Furthermore, according to international standards, at a specified irradiation angle, laser wavelength affects the maximum permissible exposure of a single pulse. At the same irradiation time, increasing the pulse frequency reduces the maximum permissible exposure of continuous pulses. At the same laser repetition rate, increasing the irradiation time also reduces the maximum permissible exposure of continuous pulses. The energy of a single pulse is lower than the energy of a repetitive pulse. In other words, the maximum permissible laser irradiation energy is determined by wavelength, repetition rate, irradiation angle, and irradiation time.

[0009] Under the constraints of the aforementioned eye-safety requirements, the more pulses a LiDAR emits during each detection, the less energy each pulse can allocate, and the shorter its detectable distance. However, emitting only a single pulse per detection cannot effectively address crosstalk, significantly impacting the quality of the LiDAR's point cloud. In the context of multi-pulse encoding technology, how to balance LiDAR's range-finding capabilities with eye-safety requirements is a pressing technical challenge in this field.

[0010] The contents of the background technology section are merely technologies known to the public and do not necessarily represent the existing technologies in this field. Summary of the Invention

[0011] In view of at least one drawback of the prior art, the present invention provides a control method for a laser radar, comprising:

[0012] S101: emitting a laser pulse signal according to a pulse code and a current energy allocation strategy, wherein the laser pulse signal includes a plurality of laser pulses using the pulse code to detect a target object;

[0013] S102: receiving echo information of the plurality of laser pulses reflected by the target object; and

[0014] S103: updating the energy allocation strategy to be adopted by the laser radar for the next transmission according to the echo information of the target object.

[0015] According to one aspect of the present invention, the sum of the energies of the multiple laser pulses is less than a first energy threshold, and the first energy threshold is determined based on the requirement that the total energy of the emitted pulses within a preset time is less than a human eye safety threshold.

[0016] According to one aspect of the present invention, wherein the plurality of laser pulses include at least one far-sighted pulse and at least one near-sighted pulse, step S103 further includes:

[0017] The ranging condition is determined according to the echo information of the target object, and when the ranging condition is the distance measurement condition, the energy of the distance measurement pulse is increased.

[0018] According to one aspect of the present invention, step S103 further includes:

[0019] When the ranging condition is a far-measuring condition, the energy of the far-measuring pulse is increased, the energy of the near-measuring pulse is reduced, and the energy of the near-measuring pulse is greater than a second energy threshold.

[0020] According to one aspect of the present invention, the distance measurement condition includes that the target object is outside a first distance range, the second energy threshold is determined according to the detection requirements of the second distance range, and the second distance range is less than or equal to the first distance range.

[0021] According to one aspect of the present invention, when the ranging condition is the far-range condition, the energy of the far-range pulse is gradually increased during each detection until the sum of the energies of the multiple laser pulses approaches the first energy threshold.

[0022] According to one aspect of the present invention, when the ranging condition is the far-range condition, the energy of the far-range pulse is increased during the next detection, so that the sum of the energies of the multiple laser pulses is close to the first energy threshold, and the energy of the near-range pulse is close to the second energy threshold.

[0023] According to one aspect of the present invention, wherein the plurality of laser pulses include at least one far-sighted pulse and at least one near-sighted pulse, step S103 further includes:

[0024] The ranging condition is determined based on the echo information of the target object. When the ranging condition is the near-range condition, the energy of the far-range pulse is reduced and the energy of the near-range pulse is increased. In the same transmission, the energy of the near-range pulse is less than or equal to the energy of the far-range pulse.

[0025] According to one aspect of the present invention, when the ranging condition is the close-range condition, the distance-measuring pulse and the close-range pulse with close energies are emitted during the next detection, and the sum of the energies of the multiple laser pulses is close to the first energy threshold.

[0026] According to one aspect of the present invention, the control method further comprises:

[0027] The intensity peak or pulse width of the multiple laser pulses is adjusted by adjusting the energy distribution of the multiple laser pulses when the laser radar is emitted next time.

[0028] According to one aspect of the present invention, the control method further comprises:

[0029] The pulse peak values ​​of the multiple laser pulses are increased by increasing the maximum driving current / voltage of the multiple laser pulses.

[0030] According to one aspect of the present invention, the control method further comprises:

[0031] The driving current / voltage is kept unchanged, and the emission time of the multiple laser pulses is prolonged / shortened to extend / shorten the pulse width of the multiple laser pulses.

[0032] According to one aspect of the present invention, the control method further comprises:

[0033] The distance of the target object is calculated according to the echo information corresponding to the multiple laser pulses.

[0034] The present invention also provides a laser radar, comprising:

[0035] a transmitting unit, configured to transmit a laser pulse signal according to the pulse code and the current energy allocation strategy, wherein the laser pulse signal includes a plurality of laser pulses using the pulse code, for detecting a target object;

[0036] a receiving unit configured to receive echo information of the plurality of laser pulses reflected by a target object;

[0037] The control unit is configured to update the energy allocation strategy adopted by the laser radar during the next transmission based on the echo information of the target object.

[0038] According to one aspect of the present invention, the sum of the energies of the multiple laser pulses is less than a first energy threshold, and the first energy threshold is determined based on the requirement that the total energy of the emitted pulses within a preset time is less than a human eye safety threshold.

[0039] According to one aspect of the present invention, wherein the plurality of laser pulses include at least one far-sighted pulse and at least one near-sighted pulse, the control unit is further configured to:

[0040] The ranging condition is determined according to the echo information of the target object, and when the ranging condition is the distance measurement condition, the energy of the distance measurement pulse is increased.

[0041] According to one aspect of the present invention, the control unit is further configured to:

[0042] When the ranging condition is a far-measuring condition, the energy of the far-measuring pulse is increased, the energy of the near-measuring pulse is reduced, and the energy of the near-measuring pulse is greater than a second energy threshold.

[0043] According to one aspect of the present invention, the distance measurement condition includes that the target object is outside a first distance range, the second energy threshold is determined according to the detection requirements of the second distance range, and the second distance range is less than or equal to the first distance range.

[0044] According to one aspect of the present invention, the transmitting unit includes at least one laser, and the laser radar further includes:

[0045] A first energy regulating unit is coupled to the at least one laser and the control unit, and is configured to regulate the driving current / voltage of the at least one laser under the control of the control unit, so as to adjust the pulse peak value of the multiple laser pulses when the laser radar is emitted next time.

[0046] According to one aspect of the present invention, the transmitting unit includes at least one laser, and the laser radar further includes:

[0047] A second energy regulating unit is coupled to the at least one laser and the control unit, and is configured to adjust the emission time of the at least one laser under the control of the control unit, so as to adjust the pulse width of the multiple laser pulses when the laser radar is emitted next time.

[0048] A preferred embodiment of the present invention provides a control method for a laser radar (LIDAR) that transmits multiple laser pulses encoded at time intervals and adjusts the energy distribution of the multiple laser pulses during the next transmission based on the target's echo information. This preferred embodiment of the present invention balances crosstalk mitigation requirements at close range while improving detection accuracy and performance at long ranges. This method maximizes the use of laser pulse energy while meeting eye safety requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0050] Figure 1A control method for a laser radar according to a preferred embodiment of the present invention is shown;

[0051] Figure 2 The figure schematically shows the curve of laser eye-safe power changing with time;

[0052] Figure 3 The laser radar's transmission pulse sequence and its echo pulse sequence are schematically shown;

[0053] Figure 4 Schematically shows the laser radar's transmitted pulse sequence and the received echo pulse sequence of other radars;

[0054] Figure 5A Schematically illustrating the transmission of at least one proximity detection pulse and at least one distance detection pulse according to a preferred embodiment of the present invention;

[0055] Figure 5B Schematically illustrating the transmission of at least one proximity detection pulse and at least one distance detection pulse according to a preferred embodiment of the present invention;

[0056] Figure 6 The figure schematically shows the echo conditions of at least one proximity detection pulse and at least one distance detection pulse in different distance ranges according to a preferred embodiment of the present invention;

[0057] Figure 7A Schematically illustrating at least one proximity detection pulse and at least one distance detection pulse having the same or similar pulse width and different peak powers transmitted according to a preferred embodiment of the present invention;

[0058] Figure 7B Schematically illustrating at least one proximity detection pulse and at least one distance detection pulse with the same or similar peak power and different pulse widths transmitted according to a preferred embodiment of the present invention;

[0059] Figure 8 Schematically shows a driving circuit of a laser according to a preferred embodiment of the present invention;

[0060] Figure 9A Schematically shows a driving circuit of a laser according to another preferred embodiment of the present invention;

[0061] Figure 9B Shown Figure 9A The timing changes of each node of the driving circuit;

[0062] Figure 10 Schematically shows an energy regulation circuit according to a preferred embodiment of the present invention;

[0063] Figure 11Schematically illustrating triggering a laser pulse signal by a switch control signal according to a preferred embodiment of the present invention;

[0064] Figure 12A Schematically illustrating triggering a double pulse under a coding by a switch control signal according to a preferred embodiment of the present invention;

[0065] Figure 12B Schematically illustrating triggering a double pulse in another encoding by a switch control signal according to a preferred embodiment of the present invention;

[0066] Figure 13 A laser radar according to a preferred embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0067] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0068] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for the purpose of facilitating the description of the present invention and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of the aforementioned features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0069] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, removable, or integral connections; mechanical, electrical, or intercommunication connections; direct or indirect connections through an intermediary; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0070] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may also include the first and second features not being in direct contact but being in contact via another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a lower level than the second feature.

[0071] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0072] The following describes embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0073] Current LiDAR systems typically use pulse coding to combat interference. The basic idea behind pulse coding is that the LiDAR emits laser pulses containing pre-coded information to detect targets. Upon receiving the echo, the pre-coded information is used to identify the reflected echo from the radar's probe beam.

[0074] Pulse coding can employ one or more of the following encoding methods: time interval coding, peak intensity coding, and pulse width coding. For example, using time interval coding, multiple laser pulses containing time-coded information are emitted. Preferably, dual laser pulses are emitted with a preset time interval. At the receiving end, the time interval between the pulse echoes is used to determine whether the echo is a reflection echo of the radar's probe beam. The two laser pulses with the preset time interval may have the same or different pulse energies, meaning dual laser pulses with different energies can be emitted.

[0075] For another example, peak intensity coding is used to emit multiple laser pulses containing peak intensity coding information. Preferably, three laser pulses are emitted whose peak intensity has a "high-low-high" variation trend. At the receiving end, based on the ratio of the peak intensities of the pulse echoes (the peak intensity of the pulse echo will be attenuated compared to the transmitted pulse, but the ratio remains basically unchanged, and a certain tolerance can be set), it is judged whether the pulse echo is the reflected echo of the detection beam emitted by this radar.

[0076] For another example, pulse width coding is used to transmit multiple laser pulses containing pulse width coding information. Preferably, three laser pulses are transmitted with a pulse width having a "wide-narrow-wide" variation trend. At the receiving end, based on the pulse width ratio of the pulse echo (the echo pulse width will be wider than the transmitted pulse, but the ratio remains basically unchanged, and a certain tolerance can be set), it is judged whether the pulse echo is the reflected echo of the detection beam emitted by this radar.

[0077] However, if pulse coding is used, multiple laser pulses need to be emitted in one detection. For eye safety reasons, the total energy of the laser radar pulses emitted in each detection is limited.

[0078] Pulse coding requires distributing the available pulse energy within a single detection across multiple laser pulses, affecting the amplitude and pulse width of each pulse. Compared to a single pulse per detection, pulse coding reduces the energy available per pulse, thus degrading the lidar's range-finding performance.

[0079] A preferred embodiment of the present invention provides a laser radar control method that maximizes the energy of the range-sensing pulse and minimizes the baseline of the near-field pulse, while meeting eye safety requirements. This method enables laser pulses carrying coded information to achieve superior range-sensing performance while also preventing crosstalk during near-field measurements. This method balances the laser radar's range-sensing performance with crosstalk prevention to maximize the efficiency of pulse energy.

[0080] According to a preferred embodiment of the present invention, Figure 1 As shown, the present invention provides a laser radar control method 10, including step S101, step S102 and step S103.

[0081] In step S101, a laser pulse signal is emitted based on the pulse coding and the current energy allocation strategy. The laser pulse signal includes multiple laser pulses using the pulse coding to detect a target. The pulse coding can use one or more of the time interval coding, peak intensity coding, and pulse width coding described above. The energy allocation strategy is based on the assumption that the total energy of the emitted pulses is less than the eye safety threshold.

[0082] Figure 2 The graph of laser power changing with time for human eye safety is shown schematically (it may be different due to different wavelengths, repetition rates, irradiation angles and irradiation times, that is, for different types of lidar, the change curve may be different). Since the total time of the emitted pulses in one detection is much less than 5μs, it is only necessary to consider the total energy of the emitted pulses in one detection that is less than the human eye safety energy threshold within 5μs (for Figure 2 The eye-safe laser power under the curve shown is integrated). Those skilled in the art will understand that Figure 2 This is only a schematic form of the eye-safe power curve corresponding to a type of lidar. The actual eye-safe power conversion may produce different curves based on the measurement standards of different dimensions and / or the type, structure, performance, etc. of the lidar.

[0083] In step S102, echo information of the multiple laser pulses reflected by the target is received, and the validity of the echo pulse is determined based on whether the echo pulse carries the same coding information as the transmitted pulse.

[0084] According to one embodiment of the present invention, Figure 3 As shown, when the timing of the echo pulse sequence is the same as the timing of the transmit pulse sequence, the echo pulse sequence is determined to be the echo signal of the transmit pulse sequence, the signal is retained, and the information carried by the signal is extracted.

[0085] According to another embodiment of the present invention, Figure 4 As shown, when the timing of the echo pulse sequence is different from the timing of the transmission pulse sequence, the echo pulse sequence is judged as the echo signal of the transmission pulse sequence emitted by other laser radars, and the echo pulse sequence is discarded.

[0086] It is easy for those skilled in the art to understand that encoding and identification based on peak intensity and pulse width, or combining one or more of time interval, peak intensity and pulse width as encoding, are also within the scope of protection of the present invention.

[0087] In step S103, the energy allocation strategy used for the next laser radar transmission is updated based on the target's echo information. The target's distance and the validity of the echo pulse are determined based on the target's echo information. The energy allocation strategy is then adjusted based on the target's distance and / or the validity of the echo pulse to achieve optimal range measurement performance while meeting eye safety requirements and ensuring anti-interference performance within a certain range.

[0088] When using multi-pulse encoding, existing technologies typically maintain relatively consistent ranging capabilities across each probe pulse, using multiple laser pulses with similar energy. Consequently, small pulses (those with low energy or power) often become a bottleneck in lidar range-finding performance.

[0089] However, in reality, the requirements for long-range and short-range LiDAR are different. When measuring distances, it is necessary to consider the long-range capability, hoping to achieve the longest possible detection distance. This requires that the laser pulses used for long-range measurement have high energy; at the same time, the probability of crosstalk during long-range measurement is low. When measuring short distances, large pulses (detection pulses with high energy or power) do not perform well, especially due to the saturation factor of the detector itself; and the probability of crosstalk increases at close ranges. Therefore, in practice, it is only necessary to provide anti-crosstalk coding at close ranges. Based on the echo information of the target, the current target range or the ranging conditions of the current LiDAR can be determined. Then, according to the distance range / ranging conditions of the target, the energy distribution of the laser pulses can be adjusted.

[0090] According to a preferred embodiment of the present invention, in the control method 10, within the time of one detection, the total energy of multiple laser pulses emitted is less than a first energy threshold, wherein the first energy threshold is determined based on the requirement that the total energy of the pulses emitted within a preset time is less than a human eye safety threshold.

[0091] Specifically, according to eye safety requirements, the total energy of laser pulses emitted by the lidar during multiple detections within a predetermined time period must be less than the eye safety threshold. This predetermined time period and the corresponding eye safety threshold vary depending on the lidar's detection method and performance.

[0092] For example, in the same period of time, the total energy that can be used by a laser radar that uses a mechanical rotational scanning detection method can be higher because it performs rotational scanning during the detection process instead of being fixed in one direction; while the energy allowed by a laser radar that uses an array flash detection method is smaller because it points in a fixed direction, and so on.

[0093] Typically, the predetermined time period is in the microsecond range, for example, approximately 5 μs. Typically, a single LiDAR detection takes between tens and hundreds of nanoseconds. In other words, a single LiDAR detection takes less than the predetermined time period.

[0094] Since the duration of a specific lidar detection is fixed, the total pulse energy available for each detection can be determined. In other words, the total energy of the multiple laser pulses emitted during a detection can be determined. For example, since the total duration of the transmitted pulses within a detection is much less than 5μs, the total energy of the transmitted pulses within a detection can be directly considered to be less than the eye safety threshold within 5μs.

[0095] In addition, according to a preferred embodiment of the present invention, in the control method 10, during one detection, the multiple laser pulses emitted include at least one far-measuring pulse and at least one near-measuring pulse, and the emission order of the at least one far-measuring pulse and the at least one near-measuring pulse is not limited, but the energy / power of the near-measuring pulse should not be greater than the energy / power of the far-measuring pulse.

[0096] Preferably, when there are multiple, such as greater than or equal to three, coded pulses of different sizes, the pulse with the largest energy can be used as the distance detection pulse, and the remaining at least two pulses can be used as the proximity detection pulses to maximize the ranging capability.

[0097] According to a preferred embodiment of the present invention, Figure 5A 、 Figure 5B As shown, a proximity detection pulse and a distance detection pulse encoded with time intervals are transmitted, wherein the order in which the proximity detection pulse and the distance detection pulse are transmitted is not limited. In addition to time interval encoding, encoding using peak intensity, pulse width, or a combination of time interval, peak intensity, and pulse width encoding methods may also be used, and all of these are within the scope of protection of the present invention.

[0098] For the sake of convenience, a dual pulse scheme with time interval coding is used as an example. Step S103 of the control method 10 further includes: determining the ranging condition according to the echo information of the target object, and increasing the energy of the ranging pulse when the ranging condition is the range condition.

[0099] Preferably, when at least one of the following conditions is met, it is determined that the radar is currently in the range finding condition:

[0100] (1) The target is outside the first distance range. For example, 80 meters away, at this time, the requirements for the laser radar's range measurement performance are higher, and the need to combat crosstalk is reduced. The first distance can be adjusted according to actual conditions and needs. Generally speaking, the first distance range is used to indicate an area where good ranging performance can be obtained based only on the range pulse;

[0101] and / or

[0102] (2) The echo of the received proximity pulse is weak or no proximity pulse is received. This may be due to a variety of reasons, such as the target being outside the first distance range, the energy of the proximity pulse being insufficient to detect the target, and being completely or nearly completely attenuated; the target having low reflectivity, etc.

[0103] like Figure 6 As shown in the figure, when the target is within a distance range of less than 50 meters, the echoes of both the near-detection pulse and the far-detection pulse can be received by the lidar; when the target is within a distance range of more than 80 meters, the lidar can only receive the echo of the far-detection pulse.

[0104] Therefore, under the condition of range measurement, it is necessary to increase the energy / power of the range measurement pulse in the next detection to increase the long-range detection accuracy of the lidar.

[0105] According to a preferred embodiment of the present invention, when the ranging condition is far measurement, the energy of the far measurement pulse is increased, and the energy of the near measurement pulse is reduced, and the energy of the near measurement pulse is greater than a second energy threshold. The second energy threshold is determined by the basic requirements of the laser radar for anti-interference performance.

[0106] Due to the aforementioned limitation that the sum of the energies of multiple laser pulses within a single detection must be less than the first energy threshold, the energy of the proximity pulse can be reduced to further increase the energy of the range-finding pulse. Under range-finding conditions, if the target is outside the first distance range (e.g., 80 meters), the requirements for range-finding performance increase, while the requirements for anti-crosstalk functionality decrease. Therefore, the energy of the proximity pulse can be appropriately reduced. Furthermore, if the proximity pulse echo is weak or no echo is received, the proximity pulse is ineffective in determining the target's distance. Therefore, the energy of the proximity pulse can also be appropriately reduced. The energy limit for proximity pulses is determined by the lidar's basic anti-crosstalk requirements. That is, when the target returns to within the second distance range (e.g., 50 meters), the requirements for anti-crosstalk functionality increase, while the requirements for range-finding performance decrease. In this case, the lidar is required to still detect and resolve the reflected echo of the detection beam emitted by the radar.

[0107] According to a preferred embodiment of the present invention, the range measurement condition includes the target being outside a first distance range (e.g., 80 meters), and the second energy threshold is determined based on the detection requirements of the second distance range (e.g., 50 meters). Those skilled in the art will readily appreciate that, while the first distance range is 80 meters and the second distance range is 50 meters in the preferred embodiment, it is also feasible to set the first distance range to be less than or equal to the first distance range based on actual detection needs, and such a technical solution is within the scope of protection of the present invention.

[0108] The energy limit for proximity pulses is that detection is still possible within the second distance range. The second distance range is where the LiDAR has high anti-crosstalk requirements. For example, within 50 meters of the LiDAR, the echo signal corresponding to the detection beam emitted by the LiDAR may be affected by other LiDARs on the vehicle or by LiDARs on nearby vehicles. The first distance range is where the LiDAR has high requirements for far-range performance. For example, within 80 meters of the LiDAR, the far-range condition includes determining that the target is outside the first distance range based on the echo information.

[0109] According to a preferred embodiment of the present invention, in control method 10, when the ranging condition is far measurement, the energy of the far measurement pulse is gradually increased during each detection until the sum of the energies of multiple laser pulses approaches a first energy threshold, while the energy of the near measurement pulse does not fall below a second energy threshold. The first energy threshold is determined based on the eye safety threshold, and the second energy threshold is determined based on the basic anti-interference performance requirements of the lidar. In other words, the energy allocation strategy is switched step by step.

[0110] For example, the first energy threshold, determined based on the eye safety threshold, is 800 nJ, and the second energy threshold, determined based on the basic anti-interference requirements of the lidar, is 100 nJ. Using a time interval-coded dual-pulse detection scheme, the energy allocation strategy is shown in the following table.

[0111] Table 1

[0112] Pulse coding Remote pulse energy Measuring near pulse energy PCode1 300nJ 300nJ PCode2 400nJ 300nJ PCode3 500nJ 300nJ PCode4 600nJ 200nJ PCode5 700nJ 100nJ

[0113] PCode1 is preset for encoding. When the ranging condition is judged to be the far-range condition according to the echo information, the energy of the far-range pulse is increased by 100nJ in the next detection, that is, switching to PCode2; when the ranging condition is still judged to be the far-range condition according to the echo information, the energy of the far-range pulse is increased by 100nJ in the next detection, that is, switching to PCode3. At this time, the sum of the energy of the two pulses has reached the first energy threshold (in the actual detection process, based on other considerations such as energy consumption, the upper limit of the sum of the energy of the two pulses can be set near the first energy threshold and not exceed the first energy threshold, such as 750nJ); when the ranging condition is still judged to be the far-range condition according to the echo information, the energy of the far-range pulse is increased by 100nJ in the next detection. The energy of the near-detection pulse is increased by 100nJ, while the energy of the near-detection pulse is reduced by 100nJ, i.e., switching to PCode 4. If the ranging condition is still far-detection according to the echo information, in the next detection, the energy of the far-detection pulse is increased by 100nJ, while the energy of the near-detection pulse is reduced by 100nJ, i.e., switching to PCode 5. At this time, the energy of the near-detection pulse has dropped to the second energy threshold. If the ranging condition is still far-detection according to the echo information, PCode 5 is continued to be used in the next detection. If the ranging condition is determined to be near-detection according to the echo information during any detection (i.e., there may be a target at close range), the code can be switched back to PCode 1. The far-detection condition includes:

[0114] (1) The distance information obtained within the predetermined time is all outside the first distance range (e.g., 80 meters). The distance of the target object is analyzed based on the echo information, and the distance information obtained within the predetermined time indicates that the target object is outside the first distance range; and / or

[0115] (2) The echo of the received proximity pulse is weak or no echo of the proximity pulse is received; and / or

[0116] (3) In some cases, when the radar optical axis is facing a specific angle (for example, facing directly in front of the vehicle), the demand for detection accuracy in the direction directly in front of the vehicle is increased, and the crosstalk condition of surrounding vehicles in the direction directly in front is improved, and the demand for anti-interference is relatively reduced.

[0117] In summary, under the condition that the first energy threshold allowed by human eye safety is not exceeded, that is, the total energy remains unchanged, the energy distribution measurement between the near detection pulse and the far detection pulse is adjusted to optimize the detection result.

[0118] It will be understood by those skilled in the art that by properly designing the circuit, the step size of the step-by-step adjustment can be made larger or smaller. Even a nearly stepless adjustment effect can be achieved. For example, by providing a resistance adjustment module that can be nearly steplessly changed, stepless adjustment of the laser energy can be achieved.

[0119] According to a preferred embodiment of the present invention, when the ranging condition is the far-range condition, the energy of the far-range pulse is increased during the next detection, such that the sum of the energies of the multiple laser pulses approaches a first energy threshold, and the energy of the near-range pulse approaches a second energy threshold. Specifically, the term "approaching" herein indicates a trend in energy adjustment, i.e., the sum of the energies of the multiple laser pulses after adjustment is closer to the first energy threshold than the sum of the energies before adjustment, and the energy of the near-range pulse after adjustment is closer to the second energy threshold than the energy before adjustment.

[0120] The first energy threshold is determined based on the eye safety threshold, for example, calculated based on laser product safety standards in various countries or regions and the type and detection mode of the actual radar product in use. The second energy threshold is determined based on the basic anti-interference performance requirements of the laser radar. This means that the energy allocation strategy is switched once.

[0121] For example, the first energy threshold, determined based on the eye safety threshold, is 800 nJ, and the second energy threshold, determined based on the basic anti-interference requirements of the lidar, is 100 nJ. Using a time interval-coded dual-pulse detection scheme, the energy allocation strategy is shown in the following table.

[0122] Table 2

[0123] Pulse coding Measuring near pulse energy Remote pulse energy PCode6 400nJ 400nJ PCode7 600nJ 200nJ

[0124] The default encoding is PCode6 as shown in Table 2. When the distance measurement conditions are met, it switches to PCode7. The distance measurement conditions include:

[0125] (1) The distance measurement information obtained within the predetermined time is all outside the first distance range (e.g., 80 meters); and / or

[0126] (2) The echo of the received proximity pulse is weak or no echo of the proximity pulse is received; and / or

[0127] (3) In some cases, the radar optical axis is facing a specific angle (for example, facing directly in front of the vehicle).

[0128] According to a preferred embodiment of the present invention, in the control method 10, the multiple laser pulses include at least one far-sighted pulse and at least one near-sighted pulse, and step S103 further includes:

[0129] The ranging condition is determined based on the echo information of the target object. When the ranging condition is the close ranging condition, the energy of the far ranging pulse is reduced and the energy of the close ranging pulse is increased. In the same transmission, the energy of the close ranging pulse is less than or equal to the energy of the far ranging pulse.

[0130] The proximity conditions include:

[0131] (1) The distance information obtained within the predetermined time is all within the second distance range (e.g., 50 meters). That is, the distance to the target object is analyzed based on the echo information, and the distance information obtained within the predetermined time indicates that the target object is within the area where crosstalk frequently occurs near the laser radar; and / or

[0132] (2) When the radar optical axis is not facing the specified angle (for example, when facing a direction other than the vehicle's front). For detection directions other than the vehicle's front, there is a possibility of mutual interference with the laser radars mounted on surrounding vehicles. The energy of the proximity pulse should be increased to improve the close-range detection performance.

[0133] According to a preferred embodiment of the present invention, when the ranging condition is close detection, a long-range detection pulse and a close-range detection pulse with similar energies are emitted during the next detection, so that the sum of the energies of the multiple laser pulses approaches a first energy threshold. A dual pulse sequence with similar energies and time intervals is emitted to optimize close-range detection performance (anti-crosstalk performance).

[0134] For example, the first energy threshold, determined based on the eye safety threshold, is 800 nJ, and the second energy threshold, determined based on the basic anti-interference requirements of the lidar, is 100 nJ. A dual-pulse detection scheme with time interval coding is used, and the energy allocation strategy is shown in Table 2 above: Currently, PCode 2 is used for encoding, and when the proximity detection condition is met, it switches to PCode 1.

[0135] According to a preferred embodiment of the present invention, the control method 10 further comprises:

[0136] By adjusting the energy distribution of multiple laser pulses during the next emission of the lidar, the intensity peak or pulse width of the multiple laser pulses can be adjusted.

[0137] Typically, when the lidar uses time interval encoding, the peak intensity and / or pulse width of the laser pulse can be adjusted to achieve the purpose of regulating energy distribution. When the lidar uses peak intensity encoding, the ratio (changing trend) of the peak intensities can be maintained unchanged, and the energy distribution can be adjusted by adjusting the pulse width. When the lidar uses pulse width encoding, the ratio (changing trend) of the pulse width can be maintained unchanged, and the energy distribution can be adjusted by adjusting the peak intensity.

[0138] According to a preferred embodiment of the present invention, Figure 7A 、 Figure 7B As shown, the near-detection pulse and the far-detection pulse in the same detection can have the same or similar pulse time, but different peak powers (such as Figure 7AAs shown), it can also be the same or similar pulse peak power, but different pulse time (such as Figure 7B For Figure 7A The embodiment shown is preferably applied to a multi-channel mechanical radar, which improves detection accuracy by using high peak power range-finding pulses and resists crosstalk by using double pulse coding. Figure 7B The embodiment shown is preferably applied to a planar array flash solid-state laser radar, which increases the probability of photon reception by using a ranging pulse with a wider pulse width and resists crosstalk by using double-pulse coding.

[0139] Specifically, depending on the pulse coding method, the operations required to adjust the peak intensity and / or pulse width are also different. For example, when only time interval coding is used, there is no need to consider the peak ratio or pulse width ratio of each pulse in the initial waveform. Therefore, when performing energy adjustment, there is no need to adjust the detection end accordingly. For example, when peak coding is used, if the pulse widths of each pulse in the initial waveform are the same but the peak values ​​are different, when changing the energy distribution, it is necessary to simultaneously update the energy distribution ratio based on which each detection end is verified. That is, the distribution ratio information used by the detection end for verification can be updated according to the adjustment of energy distribution. Similarly, when pulse width coding is used, if the pulse widths of each pulse in the initial waveform are different but the peak values ​​are the same, then when performing energy distribution adjustment, the distribution ratio information used by the detection end can also be updated accordingly.

[0140] According to a preferred embodiment of the present invention, a laser radar's transmitting unit transmits a multi-pulse sequence using time interval encoding and an energy allocation strategy. This multi-pulse sequence, for example, includes a first laser pulse and a second laser pulse (a distance detection pulse and a proximity detection pulse). Of course, this is not general and may also include a first laser pulse, a second laser pulse, and so on, the Nth laser pulse, with the multiple laser pulses having a time sequence relationship. The time intervals described above describe the timing relationship of the transmitted pulse sequence. After adjusting the energy allocation strategy, the receiving unit can still determine the reflected echo of the transmitted pulse sequence emitted by the radar by verifying the timing relationship between the echo pulse sequence and the transmitted pulse sequence.

[0141] According to another preferred embodiment of the present invention, the transmitting unit of a laser radar emits a multi-pulse sequence using peak intensity coding and an energy allocation strategy. The energy allocation strategy includes reducing the energy of the near-range pulse and increasing the energy of the far-range pulse when in range detection mode. The solution of this embodiment will be further described. This multi-pulse sequence includes a far-range pulse and a near-range pulse, with a peak ratio of 1.2:1 between the far-range pulse and the near-range pulse. Accordingly, the detector determines whether a received pulse is from its own laser radar based on whether the peak energy ratio of two consecutive received pulses meets 1.2:1.

[0142] Later, if the detection mode is determined to be far detection, the energy of the near detection pulse is reduced by 50% and the remaining 50% energy is added to the far detection pulse. The peak ratio of the far detection pulse to the near detection pulse is now 1.7:0.5, or 3.4:1. The detection end then updates the peak ratio of the echo pulse to 3.4:1. The transmitter then transmits the far detection pulse and the near detection pulse according to the new energy allocation ratio. The detection end then determines whether the received echo is the correct echo pulse based on the new energy allocation ratio.

[0143] According to another preferred embodiment of the present invention, the laser radar's transmitting unit emits a multi-pulse sequence using pulse width coding and energy allocation strategies. This multi-pulse sequence includes one strong pulse and one weak pulse, with the strong pulse and weak pulse width ratio being 2:1 (i.e., the strong pulse is twice as wide as the weak pulse). Accordingly, the detector determines whether a received pulse is from its own laser radar based on whether the pulse width ratio of two consecutive received pulses satisfies 2:1.

[0144] Later, during a detection, if the current detection mode is far detection, the energy of the near detection pulse is reduced and the energy of the far detection pulse is increased, so that the pulse width ratio of the far detection pulse to the near detection pulse is 3:1. The detection end then updates the pulse width ratio of the echo pulse to 3:1. The transmitter then transmits the far detection pulse and the near detection pulse according to the new energy allocation ratio. The detection end then determines whether the received echo is the correct echo pulse based on this new energy allocation ratio.

[0145] The LiDAR then continues detecting based on the new energy allocation ratio. If, during another detection, the current range information is 46 meters, indicating near-range detection mode, the energy of the far-range pulse is reduced while the energy of the near-range pulse is increased, resulting in a pulse width ratio of 1.5:1 between the far-range and near-range pulses. This allows the pulse coding of the far-range and near-range pulses to be better used to distinguish the pulses emitted by the LiDAR.

[0146] As a more preferred solution, the ranging mode can have multiple levels. For example, the ranging mode can be divided into medium and long range (for example, 50-100 meters) and ultra-long range (for example, greater than 100 meters). Moreover, the detection end only performs judgment based on the new energy allocation ratio in the medium and long range mode. In the ultra-long range, as long as an echo pulse is received, it is considered to be an echo pulse corresponding to the ranging pulse.

[0147] In other words, in certain detection modes, such as ultra-long-range mode, interference from other lidars or transmitters is minimal and can be ignored, and only the received pulses are considered. In this case, the detector no longer needs to verify the pulse code.

[0148] As another preferred embodiment of the present scheme, when a detection is performed using one far detection pulse and two or more near detection pulses for encoding, part of the near detection pulses can be removed, and the energy of these part of the near detection pulses can be allocated to the far detection pulses, and the anti-crosstalk judgment conditions adopted by the detection end can be adjusted accordingly to make judgments based on the pulse coding after the energy is redistributed.

[0149] For example, the laser radar initially uses three-pulse coding, and the peak ratio of the three pulses pulse1, pulse2, and pulse3 is 1:2:3. The pulse with the largest peak value is the distance measurement pulse, and the remaining two are proximity measurement pulses. At the same time, the detection end needs to determine that the echo pulse belongs to this laser radar when it receives three echo pulses and the energy ratio of the three echo pulses is 1:2:3. When the laser radar determines that it is currently in the distance measurement mode, the energy of the pulse pulse1 with the smallest energy is transferred to the largest pulse pulse3. That is, the laser radar only transmits dual-pulse coding with a peak ratio of 2:4, and updates the judgment condition of the detection end to determine that the echo pulse belongs to this laser radar when two pulses with an energy ratio of 2:4 are received. Conversely, when entering the proximity measurement mode from the distance measurement mode, the emission and detection are still carried out according to the three-pulse coding with a peak ratio of 1:2:3.

[0150] Similarly, when more pulses are used for encoding, a similar allocation method can be used to enhance the energy of the range-finding pulses in the range-finding mode and obtain better range-finding performance.

[0151] More preferably, a certain tolerance can be set for the energy distribution of the long-range pulse and the short-range pulse. After adjusting the energy distribution strategy, if the transmitting unit adjusts the energy distribution strategy by adjusting the pulse widths of multiple laser pulses, the receiving unit determines a preset proportional relationship of the pulse widths of the multi-pulse sequence transmitted for this detection based on the energy distribution strategy updated by the lidar control unit. The receiving unit then determines the reflected echo of the transmitted pulse sequence emitted by the radar by verifying the ratio of the pulse width of the echo pulse sequence to the pulse width of the transmitted pulse sequence, wherein a certain tolerance can be set.

[0152] As a preferred alternative, when the total energy of a detection is sufficient, that is, when the total energy emitted by a detection is less than the human eye safety threshold, the energy allocation measurement in the far detection case can be to only increase the energy of the far detection pulse without reducing the energy of the near detection pulse.

[0153] According to a preferred embodiment of the present invention, the control method 10 further includes: increasing the peak values ​​of the multiple laser pulses by increasing the maximum driving current / voltage of the multiple laser pulses.

[0154] Circuit implementation can be achieved in a variety of ways. For example, a voltage-adjustable drive circuit or a laser drive circuit containing multiple energy storage circuits can be used to adjust the energy of each pulse. Generally speaking, the current in a laser is proportional to the drive voltage applied to the laser and inversely proportional to the resistance of the circuit in which the laser is located. Therefore, there are two main methods for adjusting the current / voltage in a laser: one is to adjust the drive voltage, and the other is to adjust the resistance.

[0155] According to a preferred embodiment of the present invention, Figure 8 A schematic diagram of a circuit structure for adjusting the energy of the emitted pulse by adjusting the current on the laser is shown.

[0156] in, Figure 8 The laser current shown is related to the applied voltage and resistance as follows:

[0157] Imax=HVDD1 / (Rd+Rdson)

[0158] Where HVDD1 is the driving voltage applied to the laser, Rd is the equivalent resistance of the laser itself, and Rdson is the total resistance of the PMOS and other connected devices. Therefore, there are two main methods to adjust Imax: one is to adjust the voltage HVDD1, and the other is to adjust the resistance Rdson.

[0159] Based on the above-mentioned adjustable circuit, a control module is integrated. The control module can switch multiple sets of pulse codes. It can directly switch based on the above-mentioned two coding methods, or adjust the pulse codes step by step to generate pulse control signals respectively. Through the pulse control signals, the input voltage HVDD1 or the resistance value Rdson is adjusted to emit corresponding laser pulses.

[0160] According to a preferred embodiment of the present invention, Figure 9A The regulation circuit shown in the figure has a timing diagram as shown in Figure 9B As shown, in this embodiment, the laser current intensity corresponds to the magnitude of the voltage Vx, which can be adjusted by the output V2 of a low-voltage linear regulator (LDO). When V2 increases, Vx decreases, and when V2 decreases, Vx increases. By controlling the LDO output V2 accordingly, the laser current can be adjusted, and thus the emission pulse can be adjusted.

[0161] According to a preferred embodiment of the present invention, Figure 10 A circuit implementation method using an energy storage module is shown in FIG. Figure 10As shown, multiple energy storage modules are connected to the power supply module, and each energy storage module is connected to a control switch, which is responsible for controlling the on / off of the energy storage module and the laser emitting unit. When the control switch between a certain energy storage module and the laser emitting unit is closed, the charge stored in the energy storage module drives the laser emitting unit to emit light pulses. Specifically, Figure 10 The individual unit switches shown can be independent of each other, and the control switches are independently controlled by the control unit. At the same moment in the timing, the control unit can control the control switches to open or close independently. When multiple control switches are closed at the same time, the energy of the emitted laser pulse is the sum of the energies of several energy storage modules. By closing multiple control switches at the same time to emit high-energy pulses, detection of distant objects can be achieved. By controlling the number and time points of the control switches closed in the timing, the shape of the pulse emitted in the timing can be controlled. For example, at a certain moment, only one control switch is closed, then the pulse intensity emitted at that moment is 1 unit, and at a subsequent moment, N control switches are closed, then the pulse intensity emitted at the corresponding moment is N units. By controlling the number of switches closed at different times by the control unit, the timing and intensity of the emitted pulses can be controlled.

[0162] According to a preferred embodiment of the present invention, Figure 11 As shown, by controlling the emission time of multiple laser pulses, multiple laser pulses with the same or similar pulse width and different peak power are obtained. When the switch control signal (GATE1, GATE2, ..., GATEN) ends, the switch trigger signal (TRIGGER) is triggered. For example, the falling edge of the switch control signal (GATE1, GATE2, ..., GATEN) shown in the figure triggers the falling edge of the switch trigger signal (TRIGGER); without loss of generality, if the end of the switch trigger signal (TRIGGER) is the rising edge of the timing signal, then the rising edge is used as the triggering time of the switch control signal to ensure that the light-emitting process starts after the charging is completed, and the next charging-light-emitting process can be started immediately after the previous charging-light-emitting process is completed. Figure 11 In the illustrated embodiment, the time widths of the switch control signals (GATE1, GATE2, . . . , GATEN) are equal, thus ensuring that the widths of the pulses in the transmitted pulse sequence are substantially consistent.

[0163] Figure 12A 、 Figure 12B It shows that the PCode1 and PCode2 mentioned above are obtained under the triggering of the switch control signal.

[0164] According to a preferred embodiment of the present invention, the control method 10 further comprises:

[0165] Keeping the driving current / voltage unchanged, the pulse width of multiple laser pulses can be extended / shortened by extending / shortening the emission time of multiple laser pulses. Figure 7B The multiple laser pulses shown have the same or similar peak power and different pulse widths. The specific circuit implementation structure for adjusting the emission time is not described here in detail.

[0166] According to a preferred embodiment of the present invention, Figure 13 As shown, the present invention further provides a laser radar 100, comprising a transmitting unit 110, a receiving unit 120 and a control unit 130. In which:

[0167] The transmitting unit 110 transmits a laser pulse signal, which includes a plurality of laser pulses encoded at time intervals, for detecting a target object;

[0168] The receiving unit 120 is configured to receive echo information of the multiple laser pulses reflected by the target object;

[0169] The control unit 130 is configured to adjust the energy distribution of the multiple laser pulses when the laser radar transmits next time according to the echo information of the target object.

[0170] According to a preferred embodiment of the present invention, the sum of the energies of multiple laser pulses is less than a first energy threshold, and the first energy threshold is determined based on the requirement that the total energy of the emitted pulses within a preset time is less than a human eye safety threshold.

[0171] According to a preferred embodiment of the present invention, wherein the plurality of laser pulses include at least one far-sighted pulse and at least one near-sighted pulse, the control unit 130 is further configured to:

[0172] The ranging condition is determined based on the echo information of the target object. When the ranging condition is the far-range condition, the energy of the far-range pulse is increased.

[0173] According to a preferred embodiment of the present invention, the control unit 130 is further configured to:

[0174] When the ranging condition is the far-measuring condition, the energy of the far-measuring pulse is increased, the energy of the near-measuring pulse is reduced, and the energy of the near-measuring pulse is greater than the second energy threshold.

[0175] According to a preferred embodiment of the present invention, the distance measurement condition includes that the target object is outside a first distance range, the second energy threshold is determined according to the detection requirement of the second distance range, and the second distance range is less than or equal to the first distance range.

[0176] According to a preferred embodiment of the present invention, the transmitting unit 110 includes at least one laser, and the laser radar 100 further includes:

[0177] The first energy adjustment unit is coupled to the at least one laser and the control unit 130, and is configured to adjust the driving current / voltage of the at least one laser under the control of the control unit 130, so as to adjust the pulse peak value of multiple laser pulses when the laser radar 100 is emitted next time.

[0178] According to a preferred embodiment of the present invention, the transmitting unit 110 includes at least one laser, and the laser radar 100 further includes:

[0179] The second energy adjustment unit is coupled to the at least one laser and the control unit 130, and is configured to adjust the emission time of the at least one laser under the control of the control unit 130, so as to adjust the pulse width of multiple laser pulses when the laser radar 100 is emitted next time.

[0180] A preferred embodiment of the present invention provides a control method for a laser radar (LIDAR) that transmits multiple laser pulses encoded at time intervals and adjusts the energy distribution of the multiple laser pulses during the next transmission based on the target's echo information. This preferred embodiment of the present invention balances crosstalk mitigation requirements at close range while improving detection accuracy and performance at long ranges. This method maximizes the use of laser pulse energy while meeting eye safety requirements.

[0181] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for controlling a laser radar, comprising: S101: emitting a laser pulse signal according to a pulse code and a current energy allocation strategy, wherein the laser pulse signal includes a plurality of laser pulses using the pulse code to detect a target object; S102: receiving echo information of the plurality of laser pulses reflected by a target object; and S103: updating the energy allocation strategy used by the laser radar for the next transmission according to the echo information of the target object; The sum of the energies of the multiple laser pulses is less than a first energy threshold, and the first energy threshold is determined based on the requirement that the total energy of the pulses emitted within a preset time is less than a human eye safety threshold; The multiple laser pulses include at least one far-measuring pulse and at least one near-measuring pulse. Step S103 further includes: judging the ranging condition based on the echo information of the target object; when the ranging condition is the far-measuring condition, increasing the energy of the far-measuring pulse and reducing the energy of the near-measuring pulse, and the energy of the near-measuring pulse is greater than a second energy threshold.

2. The control method according to claim 1, wherein the ranging condition includes that the target object is outside a first distance range, the second energy threshold is determined according to a detection requirement of a second distance range, and the second distance range is less than or equal to the first distance range.

3. The control method according to claim 1 or 2, wherein when the ranging condition is a far-range condition, the energy of the far-range pulse is gradually increased during each detection until the sum of the energies of the multiple laser pulses approaches the first energy threshold.

4. The control method according to claim 1 or 2, wherein when the ranging condition is a far-range condition, the energy of the far-range pulse is increased during the next detection so that the sum of the energies of the multiple laser pulses is close to the first energy threshold, and the energy of the near-range pulse is close to the second energy threshold.

5. The control method according to claim 1 , wherein the plurality of laser pulses include at least one far-sighted pulse and at least one near-sighted pulse, and step S103 further comprises: The ranging condition is determined based on the echo information of the target object. When the ranging condition is the near-range condition, the energy of the far-range pulse is reduced and the energy of the near-range pulse is increased. In the same transmission, the energy of the near-range pulse is less than or equal to the energy of the far-range pulse.

6. The control method according to claim 5, wherein when the ranging condition is the close-range condition, the distance-measuring pulse and the close-range pulse with close energies are emitted during the next detection, and the sum of the energies of the multiple laser pulses is close to the first energy threshold.

7. The control method according to any one of claims 1, 2, 5 and 6, further comprising: The intensity peak or pulse width of the multiple laser pulses is adjusted by adjusting the energy distribution of the multiple laser pulses when the laser radar is emitted next time.

8. The control method according to claim 7, further comprising: The pulse peak values ​​of the multiple laser pulses are increased by increasing the maximum driving current / voltage of the multiple laser pulses.

9. The control method according to claim 7, further comprising: The driving current / voltage is kept unchanged, and the emission time of the multiple laser pulses is prolonged / shortened to extend / shorten the pulse width of the multiple laser pulses.

10. The control method according to any one of claims 1, 2, 5 and 6, further comprising: The distance of the target object is calculated according to the echo information corresponding to the multiple laser pulses.

11. A laser radar comprising: a transmitting unit, configured to transmit a laser pulse signal according to the pulse code and the current energy allocation strategy, wherein the laser pulse signal includes a plurality of laser pulses using the pulse code, for detecting a target object; a receiving unit configured to receive echo information of the plurality of laser pulses reflected by a target object; A control unit configured to update the energy allocation strategy adopted by the laser radar during the next transmission according to the echo information of the target object; The sum of the energies of the multiple laser pulses is less than a first energy threshold, and the first energy threshold is determined based on the requirement that the total energy of the pulses emitted within a preset time is less than a human eye safety threshold; The multiple laser pulses include at least one far-measuring pulse and at least one near-measuring pulse, and the control unit is further configured to: determine the ranging condition based on the echo information of the target object; when the ranging condition is the far-measuring condition, increase the energy of the far-measuring pulse and reduce the energy of the near-measuring pulse, and the energy of the near-measuring pulse is greater than a second energy threshold.

12. The laser radar as claimed in claim 11, wherein the ranging condition includes that the target object is located outside a first distance range, the second energy threshold is determined according to the detection requirements of a second distance range, and the second distance range is less than or equal to the first distance range.

13. The laser radar according to claim 11 or 12, wherein the transmitting unit comprises at least one laser, and the laser radar further comprises: A first energy regulating unit is coupled to the at least one laser and the control unit, and is configured to regulate the driving current / voltage of the at least one laser under the control of the control unit, so as to adjust the pulse peak value of the multiple laser pulses when the laser radar is emitted next time.

14. The laser radar according to claim 11 or 12, wherein the transmitting unit comprises at least one laser, and the laser radar further comprises: A second energy regulating unit is coupled to the at least one laser and the control unit, and is configured to adjust the emission time of the at least one laser under the control of the control unit, so as to adjust the pulse width of the multiple laser pulses when the laser radar is emitted next time.

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