Laser radar control method and laser radar

Abstract

A method for controlling a laser radar, comprising the steps of: S101 transmitting a laser pulse signal based on pulse coding and a current energy distribution strategy, where the laser pulse signal includes multiple target detection laser pulses using pulse coding; S102 receiving echo information of multiple laser pulses reflected by the target; and S103 updating the energy distribution strategy used in the next transmission of the laser radar based on the echo information of the target. The method achieves both the demand for crosstalk prevention in a short distance range and the improvement of detection accuracy and detection performance in a long distance range, and obtains the most efficient use of laser pulse energy while satisfying the safety requirements of human eyes.

Description

[Technical field]

[0001] The present invention generally relates to the technical field of laser detection, and more particularly to a method for controlling a laser radar and a laser radar. [Background technology]

[0002] Laser radar ranging is usually based on direct time-of-flight (TOF) method, i.e. by transmitting a narrow but high peak power laser pulse and measuring the flight time of the laser pulse between the laser radar and the target and back.

[0003] In a scene where multiple laser radars are operating simultaneously within the same measurement range, for example, when multiple laser radars are installed on one vehicle, or when multiple vehicles equipped with laser radars are close to each other, the measurement principle of laser radar is based on measuring the flight time of the transmitted laser pulse, so if each laser radar cannot determine whether the received echo pulse was sent by itself or not, there is a possibility that it will judge the received echo pulse sent from another radar to be an echo signal, resulting in an error in the distance measurement result, i.e., crosstalk. When multiple laser radars are operating simultaneously, the problem of mutual interference between different laser radars is one of the bottlenecks that restrict their development.

[0004] Currently, using the method of multi-pulse coding to recognize echo signals is an effective anti-interference method for laser radar, but the use of pulse coding affects the long-distance detection performance of the laser radar.

[0005] This is because the energy that laser radar transmits per pulse is limited by human eye safety requirements, meaning that the energy per pulse cannot be increased indefinitely and must remain below the safety threshold for the human eye.

[0006] For example, in China, according to the "People's Republic of China National Standard Laser Product Safety Part 14 User's Guide", laser devices are classified into four categories. Category 1 is a laser product whose laser radiation does not exceed the threshold of Category 1 within the corresponding wavelength and transmission duration. Category 1M is a laser product whose energy threshold does not exceed Category 1 within the wavelength range of 0.3-4 μm and uses a smaller measurement aperture. Category 2 is a laser product whose laser radiation does not exceed the threshold of Category 2 within the corresponding wavelength and transmission duration. Category 2M is a laser product whose energy threshold does not exceed Category 2 within the wavelength range of 0.7-1.4 μm and uses a smaller measurement aperture or is evaluated at a greater distance from the expressing light. Categories 3R and 3B are laser products that may exceed the energy thresholds of Category 1 and Category 2 within any wavelength range, but do not exceed the energy thresholds of each of 3R and 3B. Category 4 is a laser product whose human contact may exceed the achievable transmission limit of Category 3B.

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

[0008] In addition, according to international standards, when the irradiation angle is specified, the laser wavelength affects the maximum allowable irradiation of a single pulse. With the same irradiation time, as the transmitted pulse frequency increases, the maximum allowable irradiation of consecutive pulses decreases, and with the same laser repetition frequency, as the irradiation time increases, the maximum allowable irradiation of consecutive pulses decreases. The energy of a single pulse is lower than the energy of a repetitive pulse. That is, the maximum allowable irradiation energy of a laser is jointly determined by the wavelength, repetition frequency, irradiation angle, and irradiation time.

[0009] Under the constraints of the above-mentioned human eye safety requirements, the more pulses a laser radar transmits in one detection, the less energy is allocated to each pulse, and the closer the detection distance is. If only a single pulse is transmitted in one detection, the problem of preventing crosstalk cannot be solved well, which may have a significant impact on the point cloud quality of the laser radar. In the context of the adoption of multi-pulse coding technology, how to balance the long-distance detection capability of the laser radar with the safety requirements of the human eye is a technical problem that needs to be solved urgently in this field.

[0010] The contents of the Background Art section are merely technologies known to the publisher and do not represent prior art in the field. Summary of the Invention

[0011] In view of at least one shortcoming of the prior art, the present invention provides a S101: transmitting a laser pulse signal based on pulse coding and a current energy distribution strategy, the laser pulse signal including a plurality of target detection laser pulses using the pulse coding; S102 receiving echo information of the plurality of laser pulses reflected by a target; S103 updating the energy distribution strategy used at the next transmission of the laser radar based on echo information of the target.

[0012] According to one aspect of the invention, a sum of the energies of the multiple laser pulses is less than a first energy threshold, the first energy threshold being determined based on a requirement that the total energy of the pulses transmitted within a preset time be less than a human eye safety threshold.

[0013] According to one aspect of the present invention, the plurality of laser pulses includes at least one long-distance detection pulse and at least one short-distance detection pulse, and step S103 includes: The method further includes the step of determining a ranging condition based on the echo information of the target, and increasing energy of the long-distance detection pulse if the ranging condition is a long-distance detection condition.

[0014] According to one aspect of the present invention, step S103 includes: If the ranging condition is a long-distance detection condition, the method further includes increasing the energy of the long-distance detection pulse and decreasing the energy of the short-distance detection pulse, and the energy of the short-distance detection pulse is greater than a second energy threshold.

[0015] According to one aspect of the present invention, the long-distance detection condition includes the target being outside a first distance range, the second energy threshold is determined based on a detection need for a second distance range, and the second distance range is less than or equal to the first distance range.

[0016] According to one aspect of the present invention, when the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is increased stepwise for each detection until the sum of the energies of the multiple laser pulses approaches the first energy threshold.

[0017] According to one aspect of the present invention, when the ranging condition is a long-distance detection condition, in the next detection, the energy of the long-distance detection pulse is increased so that the sum of the energies of the multiple laser pulses approaches the first energy threshold and the energy of the short-distance detection pulse approaches the second energy threshold.

[0018] According to one aspect of the present invention, the plurality of laser pulses includes at least one long-distance detection pulse and at least one short-distance detection pulse, and step S103 includes: The method further includes a step of judging a ranging condition based on echo information of the target, and if the ranging condition is a short-distance detection condition, lowering the energy of the long-distance detection pulse and increasing the energy of the short-distance detection pulse, and the energy of the short-distance detection pulse is less than or equal to the energy of the long-distance detection pulse during the same transmission.

[0019] According to one aspect of the present invention, when the ranging condition is a short-distance detection condition, the long-distance detection pulse and the short-distance detection pulse having similar energy are transmitted in the next detection, and the sum of the energies of the multiple laser pulses approaches the first energy threshold.

[0020] According to one aspect of the present invention, the control method includes: The method further includes adjusting the intensity peak or pulse width of the plurality of laser pulses by adjusting the energy distribution of the plurality of laser pulses in a subsequent transmission of the laser radar.

[0021] According to one aspect of the present invention, the control method includes: The method further includes increasing a maximum drive current / voltage of the laser pulses to thereby increase a pulse peak of the laser pulses.

[0022] According to one aspect of the present invention, the control method includes: The method further includes the step of expanding / shortening the pulse width of the laser pulses by extending / shortening the transmission time of the laser pulses while keeping the driving current / voltage constant.

[0023] According to one aspect of the present invention, the control method includes: The method further includes calculating a distance to the target based on echo information corresponding to the plurality of laser pulses.

[0024] The present invention relates to A transmitting unit for transmitting a laser pulse signal based on a pulse coding and a current energy distribution strategy, the laser pulse signal including a plurality of target detection laser pulses using the pulse coding; a receiving unit configured to receive echo information of the plurality of laser pulses reflected by a target; and a control unit configured to update the energy distribution strategy used during a next transmission of the laser radar based on echo information of the target.

[0025] According to one aspect of the invention, a sum of the energies of the multiple laser pulses is less than a first energy threshold, the first energy threshold being determined based on a requirement that the total energy of the pulses transmitted within a preset time is less than a human eye safety threshold.

[0026] According to one aspect of the present invention, the plurality of laser pulses includes at least one long-distance detection pulse and at least one short-distance detection pulse, and the control unit further comprises: The ranging condition is determined based on the echo information of the target, and if the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is increased.

[0027] According to one aspect of the present invention, the control unit further comprises: When the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is increased and the energy of the short-distance detection pulse is decreased, and the energy of the short-distance detection pulse is greater than a second energy threshold.

[0028] According to one aspect of the present invention, the long-distance detection condition includes the target being outside a first distance range, the second energy threshold is determined based on a detection need for a second distance range, and the second distance range is less than or equal to the first distance range.

[0029] According to one aspect of the present invention, the transmitting unit includes at least one laser device, and the laser radar includes: The laser radar further includes a first energy adjustment unit coupled to the at least one laser device and the control unit and configured to adjust, under the control of the control unit, a drive current / voltage of the at least one laser device to adjust a pulse peak of the plurality of laser pulses in a next transmission of the laser radar.

[0030] According to one aspect of the present invention, the transmitting unit includes at least one laser device, and the laser radar includes: The laser radar further includes a second energy adjustment unit coupled to the at least one laser device and the control unit and configured to adjust, under control of the control unit, a transmission time of the at least one laser device to adjust a pulse width of the plurality of laser pulses in a next transmission of the laser radar.

[0031] A preferred embodiment of the present invention provides a method for controlling a laser radar, which transmits multiple laser pulses coded at time intervals, and adjusts the energy distribution of the multiple laser pulses in the next transmission according to the echo information of the target. The preferred embodiment of the present invention achieves both the need to prevent crosstalk in the short range and the improvement of detection accuracy and detection performance in the long range, while meeting the human eye safety requirements, and obtains the most efficient utilization of the laser pulse energy. [Brief description of the drawings]

[0032] The drawings are intended to provide a further understanding of the embodiments of the present invention, constitute a part of the specification, and are used to interpret the present invention together with the embodiments of the present invention, but are not intended to limit the present invention. [Figure 1] 1 shows a method for controlling a laser radar according to a preferred embodiment of the present invention. [Diagram 2] Schematic diagram of the time-dependent change curve of laser output that is safe for the human eye. [Diagram 3] 1 shows a schematic diagram of a transmission pulse sequence of a laser radar and its echo pulse sequence. [Figure 4] Schematically shows a transmission pulse sequence of a laser radar and a received echo pulse sequence of another radar. [Figure 5A] 1 illustrates a schematic diagram of transmission of at least one short-range sensing pulse and at least one long-range sensing pulse according to a preferred embodiment of the present invention; [Figure 5B] 1 illustrates a schematic diagram of transmission of at least one short-range sensing pulse and at least one long-range sensing pulse according to a preferred embodiment of the present invention; [Figure 6] 3A and 3B are schematic diagrams illustrating echo situations in different distance ranges of at least one short-distance detection pulse and at least one long-distance detection pulse according to a preferred embodiment of the present invention; [Figure 7A] 1 illustrates a schematic diagram of transmission of at least one short-range sensing pulse and at least one long-range sensing pulse having the same or similar pulse widths and different peak powers according to a preferred embodiment of the present invention; [Figure 7B] 1 illustrates a schematic diagram of transmission of at least one short range detection pulse and at least one long range detection pulse having the same or similar peak power and different pulse widths according to a preferred embodiment of the present invention; [Figure 8] 1 illustrates a schematic diagram of a driving circuit for a laser device according to a preferred embodiment of the present invention; [Figure 9A] 2 illustrates a schematic diagram of a driving circuit for a laser device according to another preferred embodiment of the present invention; [Figure 9B] 9B shows timing changes at each node of the driving circuit of FIG. 9A. [Figure 10] 1 illustrates a schematic diagram of an energy adjustment circuit according to a preferred embodiment of the present invention; [Figure 11] 4 illustrates a schematic diagram of triggering of a laser pulse signal by a switch control signal according to a preferred embodiment of the present invention; [Figure 12A]4 illustrates a schematic diagram of triggering of a coded double pulse by a switch control signal according to a preferred embodiment of the present invention; [Figure 12B] 13 illustrates a schematic diagram of triggering of another coded double pulse by a switch control signal according to a preferred embodiment of the present invention; [Figure 13] 1 illustrates a schematic diagram of a laser radar according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] In the following, merely some exemplary embodiments are briefly described. As can be recognized by those skilled in the art, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. Accordingly, the drawings and description should be regarded as illustrative in nature, and not restrictive.

[0034] In describing the present invention, it is to be understood that the orientations or positional relationships indicated by the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "up," "down," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," and the like are based on the drawings and are merely for the purpose of easily explaining and simplifying the description of the present invention, and are not to be understood as limiting the present invention, since they do not expressly or imply that the devices or elements described necessarily have a particular orientation, or are constructed or operated in a particular orientation. In addition, the terms "first" and "second" are merely for descriptive purposes, and are not to be understood as expressing or implying a relative importance or quantity of the technical features described. Thus, a feature qualified as "first" or "second" may explicitly or implicitly include one or more of said features. In describing the present invention, unless expressly and specifically limited, "plurality" means two or more than two.

[0035] In the description of the present invention, unless otherwise specified or limited, the terms "attach", "couple" and "connect" should be understood in a broad sense, for example, fixed connection, detachable connection, or integral connection, mechanical connection, electrical connection, communication, direct connection, indirect connection through an intermediate medium, internal communication between two elements, or interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific situation.

[0036] In the present invention, unless otherwise clearly defined or limited, a first feature being "above" or "below" a second feature may include a case where the first and second features are in direct contact with each other, or may include a case where the first and second features are not in direct contact with each other but are in contact with each other via another feature between them. Furthermore, a first feature being "above," "above," and "on the upper surface" of a second feature may include a case where the first feature is directly above and diagonally above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. A first feature being "below," "below," and "on the lower surface" of a second feature may include a case where the first feature is directly below and diagonally below the second feature, or simply means that the horizontal height of the first feature is smaller than that of the second feature.

[0037] The following disclosure 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 following description describes specific example components and settings. Of course, these are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference alphabetical letters in various examples, but such repetition is for the purpose of brevity and clarity and does not itself dictate a relationship between the various embodiments and / or settings being discussed. In addition, the present invention provides examples of various specific processes and materials, but one skilled in the art may recognize the use of other processes and / or other materials.

[0038] Hereinafter, the present invention will be described with reference to the drawings. It should be understood that the following embodiments are merely for the purpose of explaining and explaining the present invention, and are not intended to limit the present invention.

[0039] At present, laser radars usually adopt the pulse coding method to prevent interference. The basic idea of ​​the pulse coding method is that the laser radar transmits a laser pulse for target detection containing preset coding information, and when it receives an echo, it recognizes it by the preset coding and identifies the reflected echo of the detection beam emitted from the radar.

[0040] The pulse coding can use one or more of the coding methods such as time interval coding, peak intensity coding, pulse width coding, etc. For example, coding by time interval, transmitting multiple laser pulses containing time coding information, preferably transmitting double laser pulses with a preset time interval, and determining at the receiving side whether the echo is a reflected echo of the detection beam emitted from the radar based on the time interval of the pulse echo. The pulse energies contained in the two laser pulses with the preset time interval may be the same or different, that is, double laser pulses with different energy magnitudes can be transmitted.

[0041] Also, for example, a plurality of laser pulses containing peak intensity coding information are transmitted, preferably three laser pulses whose peak intensities have a "high-low-high" changing trend, and the receiving side determines whether the pulse echo is a reflected echo of a detection beam emitted from this radar based on the ratio of the peak intensities of the pulse echoes (the peak intensity of the pulse echo attenuates compared to the transmitted pulse, but the ratio basically does not change, and a certain tolerance can be set).

[0042] Also, for example, a plurality of laser pulses containing pulse width coding information encoded by the pulse width are transmitted, preferably three laser pulses having a pulse width changing trend of "wide-narrow-wide", and the receiving side judges whether the pulse echo is a reflected echo of a detection beam emitted from this radar based on the pulse width ratio of the pulse echo (the width of the echo pulse becomes wider than that of the transmitted pulse, but the ratio basically does not change, and a certain tolerance can be set).

[0043] However, the use of pulse coding schemes means that multiple laser pulses must be transmitted in one detection, and for human eye safety reasons the total energy of the pulses transmitted by laser radar in each detection is limited.

[0044] When using pulse coding, the available pulse energy for one search must be distributed across multiple laser pulses, affecting the amplitude / pulse width of each of the multiple laser pulses. Compared to sending only a single pulse for one search, pulse coding provides less energy for each pulse, resulting in a reduced long-range detection performance of the laser radar.

[0045] A preferred embodiment of the present invention provides a control method for a laser radar, which increases the energy of the long-distance seeking pulse as much as possible and reduces the minimum level of the short-distance seeking pulse as much as possible within the range of human eye safety requirements, so that the laser pulse containing the coded information can have better long-distance seeking performance and can also achieve anti-crosstalk effect in short-distance measurement. A trade-off is made between the long-distance seeking performance and the anti-crosstalk function of the laser radar, and the most efficient use of the pulse energy is obtained.

[0046] According to a preferred embodiment of the present invention, as shown in FIG. 1, the present invention provides a laser radar control method 10, which includes the following steps S101, S102 and S103.

[0047] In step S101, according to pulse coding and a current energy allocation strategy, a laser pulse signal is transmitted, the laser pulse signal includes a plurality of target detection laser pulses using the pulse coding, the pulse coding can use one or more of the above-mentioned time interval coding, peak intensity coding, and pulse width coding, and the premise of the energy allocation strategy is that the sum of the energy of the transmitted pulses is less than the safety threshold of human eyes.

[0048] FIG. 2 is a schematic diagram of the time-dependent change curve of the laser output safe for human eyes (which may vary with different wavelengths, repetition frequencies, irradiation angles and irradiation times, i.e., the change curve may vary with different types of laser radar). Since the total time of the pulses transmitted in one detection is much smaller than 5 μs, it is only necessary to consider making the total energy of the pulses transmitted in one detection smaller than the energy threshold safe for human eyes within 5 μs (integrating the laser output safe for human eyes in the curve shown in FIG. 2). Those skilled in the art will understand that FIG. 2 is only one schematic form of the output curve safe for human eyes corresponding to the laser radar, and the actual output conversion safe for human eyes may produce different curves according to different dimension measurement standards and / or the type, structure, performance, etc. of the laser radar.

[0049] In step S102, echo information of the multiple laser pulses reflected by a target is received, and the validity of the echo pulses is determined based on whether the echo pulses contain the same encoded information as the transmitted pulses.

[0050] According to one embodiment of the present invention, as shown in FIG. 3, if the timing of an echo pulse sequence is the same as the timing of a transmit pulse sequence, the echo pulse sequence is determined to be an echo signal of the transmit pulse sequence, the signal is retained, and the information contained in the signal is extracted.

[0051] According to another embodiment of the present invention, as shown in FIG. 4, if the timing of an echo pulse sequence differs from the timing of a transmission pulse sequence, the echo pulse sequence is determined to be an echo signal of a transmission pulse sequence transmitted from another laser radar, and the echo pulse sequence is discarded.

[0052] Those skilled in the art will easily understand that coding and recognition based on peak intensity, pulse width, or coding based on one or more combinations of time interval, peak intensity, and pulse width are also within the scope of protection of the present invention.

[0053] In step S103, the energy distribution strategy used in the next transmission of the laser radar is updated according to the echo information of the target. The distance of the target and the validity of the echo pulse are determined according to the echo information of the target, and the energy distribution strategy is adjusted according to the distance of the target and / or the validity of the echo pulse, thereby achieving optimal long-distance detection performance while satisfying the safety requirements of human eyes, and also ensuring anti-interference performance within a certain distance range.

[0054] When using the multi-pulse coding method, the prior art usually uses multiple laser pulses with similar transmission energy so that each detection pulse maintains a relatively consistent ranging capability, and therefore the small pulses (detection pulses with low energy or power) among them often become a bottleneck in the long-distance detection performance of the laser radar.

[0055] However, in reality, the requirements for long-distance detection and short-distance detection by laser radar are different. During long-distance detection, it is necessary to consider the long-distance detection capability, and it is expected to achieve the longest possible detection distance, which requires that the laser pulse during long-distance detection can have high energy. In addition, the probability of crosstalk occurring during long-distance detection is low. On the other hand, during short-distance detection, especially due to the influence of the saturation factor of the detector itself, the performance of large pulses (detection pulses with high energy or output) is not outstanding. In addition, the probability of crosstalk occurring at short distances increases. Therefore, in practice, it is necessary to provide anti-crosstalk coding only at short distances, and based on the echo information of the target, the current target distance range or the current laser radar distance measurement conditions are determined, and then the energy distribution of the laser pulse is adjusted based on the target distance range / distance measurement conditions.

[0056] According to a preferred embodiment of the present invention, in the control method 10, within one detection time, the sum of the energies of the transmitted laser pulses is less than a first energy threshold, where the first energy threshold is determined based on a requirement that the sum of the energies of the transmitted pulses within a preset time is less than the safety threshold of human eyes.

[0057] Specifically, according to the human eye safety requirements, the total energy of the laser pulses transmitted by the laser radar in multiple detections within a predetermined period of time should be less than the human eye safety threshold, where the predetermined period of time and the corresponding human eye safety threshold are different for different detection methods and performances of the laser radar.

[0058] For example, in the same period of time, a laser radar using a mechanical rotary scanning detection method can have a relatively high total usable energy because it rotates and scans rather than being fixed in one direction during the detection process, whereas a laser radar using an area array flash detection method has a smaller allowable energy because it points in a fixed direction.

[0059] Generally, the predetermined period is a time interval of a microsecond level, for example, about 5 μs. Usually, the time required for one detection of a laser radar is on the level of several tens of nanoseconds to a hundred nanoseconds. In other words, the time required for one detection of a laser radar is shorter than the predetermined period.

[0060] Since the time taken for one detection of a particular laser radar is deterministic, it is possible to determine the total pulse energy available for each detection, i.e., the total energy of multiple laser pulses transmitted in one detection. For example, since the total time for which a pulse is transmitted in one detection is much smaller than 5 μs, it may be directly considered to make the total energy of the pulses transmitted in one detection smaller than the human eye safety threshold within 5 μs.

[0061] In addition, according to a preferred embodiment of the present invention, in the control method 10, the multiple laser pulses transmitted in one detection include at least one long-distance detection pulse and at least one short-distance detection pulse, and the order of transmission of the at least one long-distance detection pulse and the at least one short-distance detection pulse is not limited, but the energy / power of the short-distance detection pulse should be less than or equal to the energy / power of the long-distance detection pulse.

[0062] Preferably, when there are multiple coded pulses of different magnitudes (e.g., three or more), in order to maximize the ranging capability, the pulse with the highest energy can be designated as the long-range detection pulse, and at least the remaining two pulses can be designated as short-range detection pulses.

[0063] According to a preferred embodiment of the present invention, as shown in Figures 5A and 5B, one short range detection pulse and one long range detection pulse coded by time interval are transmitted, and the order of transmission of the short range detection pulse and the long range detection pulse is not limited. In addition to coding by time interval, coding by peak intensity, pulse width, or a combination of multiple coding methods among time interval, peak intensity, and pulse width can also be used, all of which are within the scope of protection of the present invention.

[0064] For convenience of explanation, a method of transmitting double pulses coded with time intervals is taken as an example. Step S103 of the control method 10 further includes: determining a ranging condition according to the echo information of the target; and increasing the energy of the long-distance detection pulse if the ranging condition is a long-distance detection condition.

[0065] Preferably, when at least one of the following conditions (1) and (2) is satisfied, it is determined that the radar is currently in a long-distance detection condition.

[0066] (1) The target is outside the first distance range. For example, the target is outside 80 meters, and the requirements for the long-distance detection performance of the laser radar are high, and the demand for crosstalk prevention is low. Here, the first distance can be adjusted according to the actual situation and requirements, and the first distance range is usually for indicating an area where good ranging performance can be obtained only by the long-distance detection pulse. and / or (2) The received echo of the short-distance detection pulse is weak or no echo of the short-distance detection pulse is received. In this case, there are many possible reasons, such as the target is outside the first distance range, the energy of the short-distance detection pulse is not enough to detect the target, and is attenuated completely or almost completely, or the reflectivity of the target is low, etc.

[0067] As shown in Figure 6, when the target is within a distance range of less than 50 meters, the laser radar can receive the echoes of both the short-distance detection pulse and the long-distance detection pulse, and when the target is within a distance range of more than 80 meters, the laser radar can only receive the echo of the long-distance detection pulse.

[0068] Therefore, under long-range detection conditions, it is necessary to improve the accuracy of long-range detection of the laser radar by increasing the energy / output of the long-range detection pulse in the next detection.

[0069] According to a preferred embodiment of the present invention, when the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is increased, the energy of the short-distance detection pulse is decreased, and the energy of the short-distance detection pulse is greater than a second energy threshold, where the second energy threshold is determined according to the basic requirement for anti-interference of the laser radar.

[0070] Since there is a restriction that the sum of the energies of a plurality of laser pulses in one detection must be less than the first energy threshold as described above, the energy of the long-distance detection pulse can be further increased by lowering the energy of the short-distance detection pulse. Under the condition of long-distance detection, if the target is outside the first distance range (e.g., 80 meters), the requirements for the performance of long-distance detection are increased and the demand for the anti-crosstalk function is decreased, so that the energy of the short-distance detection pulse can be appropriately reduced. And / or, if the echo of the short-distance detection pulse is weak or the echo of the short-distance detection pulse is not received, the short-distance detection pulse cannot play a substantial role in analyzing the distance to the target, so that the energy of the short-distance detection pulse can be appropriately reduced. The limit on the energy of the short-range detection pulse is determined by the basic anti-crosstalk requirements of the laser radar, i.e., when the target returns within a second distance range (e.g. 50 meters), the requirements for the anti-crosstalk function of the laser radar increase and the requirements for the long-range detection performance decrease, in which case the laser radar is still required to detect and recognize the reflected echo of the detection beam transmitted by the radar.

[0071] According to a preferred embodiment of the present invention, the long-distance detection condition includes that the target is outside a first distance range (e.g., 80 meters), and the second energy threshold is determined based on the detection demand of a second distance range (e.g., 50 meters). Those skilled in the art can easily understand that although the first distance range is 80 meters and the second distance range is 50 meters in the preferred embodiment, the first distance range can also be set to a value less than 50 meters according to the actual detection demand, and all of these are within the scope of protection of the present invention.

[0072] The energy limit of the short-distance detection pulse is that it can be detected within a second distance range, and the second distance range is a range where the demand for preventing crosstalk of the laser radar is high. For example, within a range of 50 meters near the laser radar, the echo signal corresponding to the detection beam emitted from the laser radar may be affected by other laser radars mounted on the vehicle, and may also be affected by laser radars mounted on vehicles passing nearby. Meanwhile, the first distance range is a range where the demand for long-distance detection performance of the laser radar is high, for example, a range of 80 meters away from the laser radar, and the long-distance detection condition includes that the target is analyzed to be outside the first distance range based on the echo information.

[0073] According to a preferred embodiment of the present invention, in the control method 10, when the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is gradually increased in each detection until the sum of the energies of the multiple laser pulses approaches a first energy threshold, in which the energy of the short-distance detection pulse is equal to or greater than a second energy threshold, where the first energy threshold is determined based on the safety threshold of the human eye, and the second energy threshold is determined based on the basic requirement for the anti-interference performance of the laser radar, that is, the energy distribution strategy is switched stepwise.

[0074] For example, the first energy threshold determined based on the safety threshold of human eyes is 800nJ, and the second energy threshold determined based on the basic anti-interference requirements of the laser radar is 100nJ. Using the time-coded double pulse detection method, the energy distribution strategy is shown in the table below.

[0075] [Table 1]

[0076] The preset is coded by PCode1, and if it is determined from the echo information that the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is increased by 100nJ in the next detection, that is, switched to PCode2. If it is determined from the echo information that the ranging condition is still a long-distance detection condition, the energy of the long-distance detection pulse is increased by 100nJ in the next detection, that is, switched to PCode3, and at this time, the sum of the energy of the double pulse reaches 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 double pulse can be set close to and not exceeding the first energy threshold, for example, 750nJ). If it is determined from the echo information that the ranging condition is still a long-distance detection condition, the energy of the long-distance detection pulse is increased by 100nJ in the next detection, and the energy of the short-distance detection pulse is decreased by 100nJ, that is, switched to PCode4. If it is determined from the echo information that the ranging conditions are still the long-distance detection conditions, the energy of the long-distance detection pulse is increased by 100 nJ and the energy of the short-distance detection pulse is decreased by 100 nJ in the next detection, i.e., switched to PCode5, and at this time, the energy of the short-distance detection pulse has decreased to the second energy threshold. If it is determined from the echo information that the ranging conditions are still the long-distance detection conditions, the next detection continues to use PCode5 for detection. For example, in any detection, if it is determined from the echo information that the ranging conditions are the short-distance detection conditions (i.e., when a target may exist in the short distance), the coding can be switched back to PCode1...where the long-distance detection conditions include the following (1) to (3).

[0077] (1) All of the distance measurement information obtained within a predetermined time is outside a first distance range (e.g., 80 meters). Analyze the distance of the target based on the echo information, and all of the distance measurement information obtained within the predetermined time indicates that the target is outside the first distance range. And / or (2) The received short-distance detection pulse echo is weak or no short-distance detection pulse echo is received; and / or (3) In some cases, when the optical axis of the radar is directed at a certain angle (for example, when it is directed directly ahead of the vehicle), the demand for detection accuracy is high when the vehicle is directly ahead, and the crosstalk situation of surrounding vehicles is improved when the vehicle is directly ahead, so the demand for interference prevention is relatively low.

[0078] In summary, the energy distribution measurements are adjusted between the near-range and far-range detection pulses to optimize the detection result without exceeding the first energy threshold acceptable for human eye safety, i.e., keeping the total energy constant.

[0079] Here, those skilled in the art will understand that by rationally designing the circuit, the step size of the stepwise adjustment can be increased or decreased, and even an effect close to stepless adjustment can be achieved, for example, by providing a resistance adjustment module that can be changed almost steplessly, thereby achieving stepless adjustment of the energy of the laser device.

[0080] According to a preferred embodiment of the present invention, when the ranging condition is the long-distance detection condition, in the next detection, the energy of the long-distance detection pulse is increased so that the sum of the energies of the multiple laser pulses approaches the first energy threshold and the energy of the short-distance detection pulse approaches the second energy threshold. Specifically, the word "approaching" here is used to indicate the tendency of the energy adjustment, that is, 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 short-distance detection pulse after adjustment is closer to the second energy threshold than the energy before adjustment.

[0081] Here, the first energy threshold is determined based on the safety threshold of human eyes, for example, the first energy threshold can be calculated based on the laser product safety standard of each country or region and the type and detection mode of the radar product actually used. The second energy threshold is determined based on the basic demand for the anti-interference performance of the laser radar, that is, the energy distribution strategy is switched only once.

[0082] For example, the first energy threshold determined based on the safety threshold of human eyes is 800nJ, and the second energy threshold determined based on the basic anti-interference requirements of the laser radar is 100nJ. Using the time-coded double pulse detection method, the energy distribution strategy is shown in the table below.

[0083] [Table 2]

[0084] The preset is coded with PCode6 shown in Table 2, and when the long-distance detection conditions are met, it switches to PCode7. The long-distance detection conditions include the following (1) to (3).

[0085] (1) All of the distance measurements obtained within a predetermined time period are outside a first distance range (e.g., 80 meters); and / or (2) The received short-distance detection pulse echo is weak or no short-distance detection pulse echo is received; and / or (3) In some cases, when the radar's optical axis is pointed at a particular angle (for example, directly ahead of the moving vehicle).

[0086] According to a preferred embodiment of the present invention, in the control method 10, the plurality of laser pulses includes at least one long-distance detection pulse and at least one short-distance detection pulse, and step S103 includes: The method further includes a step of judging the ranging condition based on the echo information of the target, and if the ranging condition is the short-distance detection condition, lowering the energy of the long-distance detection pulse and raising the energy of the short-distance detection pulse, and the energy of the short-distance detection pulse is less than or equal to the energy of the long-distance detection pulse during the same transmission.

[0087] Here, the short-range detection conditions include the following (1) and (2). (1) All of the distance measurement information obtained within a predetermined time is within a second distance range (e.g., 50 meters), i.e., the distance of the target is analyzed based on the echo information, and all of the distance measurement information obtained within the predetermined time indicates that the target is within an area near the laser radar where crosstalk frequently occurs; and / or (2) When the optical axis of the radar is not directed at the specific angle (for example, when directed in a direction other than directly ahead of the vehicle). In the case of a detection direction other than directly ahead of the vehicle, there may be mutual interference with the laser radar mounted on the surrounding vehicles, so the energy of the short-range detection pulse should be increased to improve the short-range detection performance.

[0088] According to a preferred embodiment of the present invention, when the ranging condition is a short-distance detection condition, a long-distance detection pulse and a short-distance detection pulse having close energies are transmitted in the next detection, and the sum of the energies of the multiple laser pulses is close to a first energy threshold. By transmitting a double pulse sequence coded with close energies at time intervals, the short-distance detection performance (crosstalk prevention performance) is optimized.

[0089] For example, the first energy threshold determined based on the safety threshold of the human eye is 800nJ, and the second energy threshold determined based on the basic anti-interference requirements of the laser radar is 100nJ. A detection method using double pulses coded with time intervals is used, and the energy distribution strategy is as shown in Table 2 above. It is coded with PCode2 for a while, but when the short-distance detection condition is met, it switches to PCode1.

[0090] According to a preferred embodiment of the present invention, the control method 10 comprises: The method further includes adjusting the intensity peak or pulse width of the multiple laser pulses by adjusting the energy distribution of the multiple laser pulses in a subsequent transmission of the laser radar.

[0091] Usually, when the laser radar encodes by time interval, it can adjust both the peak intensity and / or the pulse width of the laser pulse to achieve the purpose of adjusting the energy distribution.When the laser radar encodes by peak intensity, it can adjust the energy distribution by keeping the peak intensity ratio (change trend) constant and adjusting the pulse width.When the laser radar encodes by pulse width, it can adjust the energy distribution by keeping the pulse width ratio (change trend) constant and adjusting the peak intensity.

[0092] According to a preferred embodiment of the present invention, as shown in Figures 7A and 7B, the short-distance detection pulse and the long-distance detection pulse in the same detection may have the same or similar pulse time but different peak power (as shown in Figure 7A), or may have the same or similar pulse peak power but different pulse time (as shown in Figure 7B). The embodiment shown in Figure 7A is preferably applied to a multi-channel mechanical radar, where the long-distance detection pulse with high peak power is used to improve detection accuracy and double pulse coding is used to prevent crosstalk. The embodiment shown in Figure 7B is preferably applied to an area array flash solid-state laser radar, where the long-distance detection pulse with wide pulse width is used to increase the probability of photon reception and double pulse coding is used to prevent crosstalk.

[0093] Specifically, the operation required for adjusting the peak intensity and / or pulse width differs depending on the pulse coding method. For example, when coding is performed only by time interval, there is no need to consider the peak ratio or pulse width ratio of each pulse in the initial waveform, so that the detection side does not need to be adjusted accordingly when adjusting the energy. For example, when coding is performed by peak, if the pulse width of each pulse in the initial waveform is the same and the peaks are different, when changing the energy distribution, the energy distribution ratio based on each detection side needs to be updated at the same time during verification, that is, the distribution ratio information used by the detection side for verification can be updated according to the adjustment of the energy distribution. Similarly, when coding is performed by pulse width, the pulse width of each pulse in the initial waveform is different and the peak is the same, so that the distribution ratio information used by the detection side can be updated accordingly when adjusting the energy distribution.

[0094] According to a preferred embodiment of the present invention, the transmitting unit of the laser radar transmits a multi-pulse sequence using a time interval coding and energy distribution strategy, the multi-pulse sequence includes, for example, a first laser pulse and a second laser pulse (one long-distance search pulse and one short-distance search pulse), and of course, not generally, the first laser pulse, the second laser pulse, ... Nth laser pulse, and the laser pulses are in a timing relationship. The above time interval represents the timing relationship of the transmitting pulse sequence, and after adjusting the energy distribution strategy, the receiving unit can still identify the reflected echo of the transmitting pulse sequence emitted from the radar by verifying the timing relationship between the echo pulse sequence and the transmitting pulse sequence.

[0095] According to another preferred embodiment of the present invention, the transmitting unit of the laser radar transmits a multi-pulse sequence using peak intensity coding and energy distribution strategy, where the energy distribution strategy includes decreasing the energy of the short-distance detection pulse and increasing the energy of the long-distance detection pulse when it is in a long-distance detection mode. The embodiment will be described below. The multi-pulse sequence includes one long-distance detection pulse and one short-distance detection pulse, and the peak ratio of the long-distance detection pulse and the short-distance detection pulse is 1.2:1. According to this, the detection side judges whether the pulse received is the laser radar pulse that belongs to itself according to whether the peak energy ratio of two consecutively received pulses meets 1.2:1.

[0096] Then, when it is found that the detection is currently in long range detection mode, the energy of the short range detection pulse is reduced by 50%, and the 50% energy is added to the long range detection pulse, and at this time, the peak ratio of the long range detection pulse and the short range detection pulse may be 1.7:0.5, that is, 3.4:1, and the peak ratio for the detection side to judge the echo pulse is updated to 3.4:1 accordingly. Then, the transmission side transmits the long range detection pulse and the short range detection pulse according to the new energy distribution ratio measurement, and the detection side judges whether the received echo is a correct echo pulse according to the new energy distribution ratio.

[0097] According to another preferred embodiment of the present invention, the transmitting unit of the laser radar transmits a multi-pulse sequence using pulse width coding and energy distribution strategy, the multi-pulse sequence includes one strong pulse and one weak pulse, and the pulse width ratio of the strong pulse and the weak pulse is 2:1, that is, the pulse width of the strong pulse is twice as long as that of the weak pulse.Accordingly, the detection side judges whether the received pulse is the laser radar pulse that belongs to itself according to whether the pulse width ratio of two consecutively received pulses meets 2:1.

[0098] Then, when it is found in the detection that the current mode corresponds to the long-distance detection mode, the energy of the short-distance detection pulse is decreased and the energy of the long-distance detection pulse is increased so that the pulse width ratio of the long-distance detection pulse and the short-distance detection pulse becomes 3:1, and the pulse width ratio for the detection side to judge the echo pulse is updated to 3:1 accordingly. Then, the transmitting side transmits the long-distance detection pulse and the short-distance detection pulse based on the new energy distribution ratio measurement, and the detection side judges whether the received echo is an accurate echo pulse based on the new energy distribution ratio.

[0099] Then, the laser radar continues to detect based on the new energy distribution ratio, and in further detection, if it is found that the current distance information is 46 meters, which corresponds to the short-range detection mode, it reduces the energy of the long-range detection pulse and increases the energy of the short-range detection pulse, so that the pulse width ratio of the long-range detection pulse and the short-range detection pulse is 1.5:1, thereby making it possible to more effectively utilize the pulse coding of the long-range detection pulse and the short-range detection pulse to recognize the pulse transmitted by the laser radar.

[0100] As a more preferred embodiment, the long-distance detection mode can have multiple levels, for example, the long-distance detection mode can be divided into medium-to-long distance (e.g., 50 to 100 meters) and ultra-long distance (e.g., over 100 meters), and the detection side makes a judgment based on the new energy distribution ratio only in the medium-to-long distance mode, and in the ultra-long distance case, if an echo pulse is received, it is regarded as an echo pulse corresponding to the long-distance detection pulse.

[0101] That is, in some detection modes, such as ultra-long range modes, the interference from other laser radars or transmission sources is so small that it can be ignored, so only the pulses that can be received need to be considered. In this case, the detection side does not need to verify the pulse coding.

[0102] As a further preferred embodiment of this embodiment, when encoding is performed using one long-distance detection pulse and two or more short-distance detection pulses in one detection, a part of the short-distance detection pulse is removed, and the energy of that part of the short-distance detection pulse is distributed to the long-distance detection pulse, and the crosstalk prevention judgment conditions used by the detection side are adjusted accordingly, and judgment is made based on the pulse encoding after the energy is redistributed.

[0103] For example, the laser radar first uses three pulses for coding, and the peak ratio of the three pulses, pulse1, pulse2, and pulse3, is 1:2:3, among which the pulse with the highest peak is the long-distance detection pulse, and the remaining two are short-distance detection pulses. In addition, the detection side 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 long-distance detection mode, it distributes the energy of the pulse pulse1 with the lowest energy to the pulse pulse3 with the highest energy, that is, the laser radar only transmits double-pulse coding with a peak ratio of 2:4, and updates the judgment condition of the detection side so that it determines that the echo pulse belongs to this laser radar when it receives two pulses with an energy ratio of 2:4. Conversely, when it transitions from the long-distance detection mode to the short-distance detection mode, it still transmits and detects according to the three-pulse coding with a peak ratio of 1:2:3.

[0104] Similarly, when coding using more pulses, a similar distribution scheme can be adopted, thereby enhancing the energy of the long-range detection pulse in the long-range detection mode, thereby achieving the purpose of obtaining higher long-range detection performance.

[0105] More preferably, a certain tolerance can be set for the energy distribution of the long-distance detection pulse and the short-distance detection pulse. After adjusting the energy distribution strategy, when the transmitting unit adjusts the energy distribution strategy by adjusting the pulse width of the multiple laser pulses, the receiving unit determines a preset ratio relationship of the pulse width of the multi-pulse sequence transmitted in this detection according to the energy distribution strategy updated by the control unit of the laser radar, and then identifies the reflected echo of the transmission pulse sequence emitted from this radar by verifying the ratio of the pulse width of the echo pulse sequence and the transmission pulse sequence, where a certain tolerance can be set.

[0106] As a preferred alternative, if there is a margin for the total energy of one detection, i.e., if the total energy transmitted in one detection is less than the safety threshold for the human eye, the energy distribution measurement in the case of long-range detection may only increase the energy of the long-range detection pulse without reducing the energy of the short-range detection pulse.

[0107] According to a preferred embodiment of the present invention, the control method 10 further includes the step of increasing the pulse peak of the plurality of laser pulses by increasing the maximum driving current / voltage of the plurality of laser pulses.

[0108] The circuit implementation can take various forms, for example, a laser device driver circuit including a voltage adjustable driver circuit and multiple energy storage circuits can be used to adjust the energy of each pulse. Typically, the current on the laser device is proportional to the drive voltage applied to the laser device and inversely proportional to the resistance of the circuit in which the laser device is located. Therefore, there are two main ways to adjust the current / voltage on the laser device: one is to adjust the drive voltage, and the other is to adjust the resistance.

[0109] According to one preferred embodiment of the present invention, FIG. 8 shows a schematic diagram of an implementation of a circuit structure that allows adjusting the energy of the transmitted pulses by adjusting the current on the laser device.

[0110] Here, the current, applied voltage, and resistance of the laser device shown in FIG. 8 have the following relationship: Imax = HVDD1 / (Rd+Rdson) In the formula, HVDD1 is the driving voltage applied to the laser device, Rd is the equivalent resistance of the laser device itself, and Rdson is the total resistance of the PMOS and other devices connected to it. Therefore, there are mainly two ways to adjust Imax: one is to adjust the voltage HVDD1, and the other is to adjust the resistance Rdson.

[0111] A control module is integrated based on the above adjustable circuit, and the control module can switch between multiple sets of pulse coding, and can directly switch according to the above two coding methods, or adjust the pulse coding step by step to generate a pulse control signal, and adjust the output voltage HVDD1 or the resistance value Rdson according to the pulse control signal to send a corresponding laser pulse.

[0112] According to a preferred embodiment of the present invention, the timing diagram of the adjustment circuit shown in Figure 9A is as shown in Figure 9B. In this embodiment, the current intensity of the laser device corresponds to the magnitude of the voltage Vx, and Vx can be adjusted by V2 output from a low-voltage linear regulator (LDO). When V2 is large, Vx is small, and when V2 is small, Vx is large. By controlling the LDO to output the corresponding V2, the adjustment to the current of the laser device can be realized, that is, the adjustment of the transmission pulse is realized.

[0113] According to a preferred embodiment of the present invention, FIG. 10 is a schematic diagram showing the implementation of a circuit using an energy storage module. As shown in FIG. 10, multiple energy storage modules are connected to a power supply module, and each energy storage module is connected to one control switch, which is responsible for controlling the on-off of the energy storage module and the laser transmission unit. When the control switch between an energy storage module and a laser transmission unit is closed, the charge stored in the energy storage module drives the laser transmission unit to transmit a light pulse. Specifically, the switches of each unit shown in FIG. 10 may be independent of each other, and the control switches are independently controlled by the control unit, and at the same time of the timing, the control unit can control the control switches to open and close independently. When multiple control switches are closed at the same time, the energy of the transmitted laser pulse is the sum of the energies of the multiple energy storage modules. By simultaneously closing multiple control switches at the same time to transmit a high-energy pulse, detection of a long-distance object can be realized. By controlling the number and time of the control switches closed within the timing, the shape of the pulse transmitted within the timing can be controlled. For example, if only one controlled switch is closed at a certain time, the pulse strength transmitted at that time will be 1 unit, and if N controlled switches are closed at a subsequent time, the pulse strength transmitted at the corresponding time will be N units. By controlling the number of switches closed at different times by the control unit, the timing and strength at which the pulses are transmitted can be controlled.

[0114] According to a preferred embodiment of the present invention, as shown in FIG. 11, by controlling the transmission time of multiple laser pulses, multiple laser pulses with the same or similar pulse width and different peak power are obtained. The switch trigger signal (TRIGGER) is triggered at the end of the switch control signal (GATE1, GATE2, ..., GATEN), for example, the timing 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, the rising edge is taken as the trigger opportunity of the switch control signal, ensuring that the light-emitting process is started after the charging is finished, and the next charging-light-emitting process is started immediately after the previous charging-light-emitting process is finished. In the embodiment shown in FIG. 11, the time widths of the switch control signals (GATE1, GATE2, ..., GATEN) are equal, thereby ensuring that the pulse widths of each pulse in the transmitted pulse sequence are approximately the same.

[0115] 12A and 12B show that the aforementioned PCode1 and PCode2 are obtained by triggering a switch control signal.

[0116] According to a preferred embodiment of the present invention, the control method 10 comprises: The method further includes a step of expanding / shortening the pulse width of the laser pulses by extending / shortening the transmission time of the laser pulses while keeping the driving current / voltage constant. That is, a plurality of laser pulses having the same or similar peak power and different pulse widths as shown in FIG. 7B are obtained. The specific circuit implementation structure for adjusting the transmission time is not described here.

[0117] According to a preferred embodiment of the present invention, as shown in FIG. 13, the present invention further provides a laser radar 100, which includes a transmitting unit 110, a receiving unit 120 and a control unit 130, where: The transmitting unit 110 transmits a laser pulse signal, which includes a plurality of target-detecting laser pulses encoded with time intervals. The receiving unit 120 is configured to receive echo information of the multiple laser pulses reflected by a target. The control unit 130 is configured to adjust the energy distribution of the multiple laser pulses in a subsequent transmission of the laser radar based on the target echo information.

[0118] According to a preferred embodiment of the present invention, the sum of the energies of the multiple laser pulses is less than a first energy threshold, the first energy threshold being determined based on a requirement that the total energy of the pulses transmitted within a preset time is less than the human eye safety threshold.

[0119] According to a preferred embodiment of the present invention, the plurality of laser pulses includes at least one long-distance detection pulse and at least one short-distance detection pulse, and the control unit 130 further comprises: The ranging condition is determined based on the echo information of the target, and if the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is increased.

[0120] According to a preferred embodiment of the present invention, the control unit 130 further comprises: When the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is increased and the energy of the short-distance detection pulse is decreased, and the energy of the short-distance detection pulse is greater than a second energy threshold.

[0121] According to one preferred embodiment of the present invention, the long-distance detection condition includes the target being outside a first distance range, and the second energy threshold is determined based on a detection need for a second distance range, the second distance range being less than or equal to the first distance range.

[0122] According to a preferred embodiment of the present invention, the transmitting unit 110 includes at least one laser device, and the laser radar 100 is The laser radar 100 further includes a first energy adjustment unit coupled to the at least one laser device and the control unit 130 and configured to adjust, under the control of the control unit 130, a driving current / voltage of the at least one laser device to adjust the pulse peak of multiple laser pulses in a next transmission of the laser radar 100.

[0123] According to a preferred embodiment of the present invention, the transmitting unit 110 includes at least one laser device, and the laser radar 100 is The laser radar 100 further includes a second energy adjustment unit coupled to the at least one laser device and the control unit 130 and configured to adjust, under the control of the control unit 130, the transmission time of the at least one laser device to adjust the pulse width of multiple laser pulses in a next transmission.

[0124] A preferred embodiment of the present invention provides a method for controlling a laser radar, which transmits multiple laser pulses coded at time intervals, and adjusts the energy distribution of the multiple laser pulses in the next transmission according to the echo information of the target. The preferred embodiment of the present invention achieves both the need to prevent crosstalk in the short range and the improvement of detection accuracy and detection performance in the long range, while meeting the human eye safety requirements, and obtains the most efficient utilization of the laser pulse energy.

[0125] Finally, it should be noted that the above are only 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 above embodiments, those skilled in the art may modify the technical solutions described in the above embodiments or make equivalent replacements for some of the technical features. All modifications, equivalent replacements, improvements, etc. made without departing from the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. S101: Transmitting a laser pulse signal based on pulse coding and a current energy distribution strategy, the laser pulse signal including a plurality of laser pulses for target detection using the pulse coding; S102 receiving echo information of the plurality of laser pulses reflected by a target, and judging a ranging condition of the target based on the echo information; S103. updating the energy allocation strategy used at the next transmission of the laser radar based on the ranging condition of the target; the plurality of laser pulses includes at least one long-range detection pulse and at least one short-range detection pulse; the energy distribution strategy is configured to distribute energy among the plurality of laser pulses and control a sum of the energy of the plurality of laser pulses to be less than a first energy threshold, the first energy threshold being determined based on a requirement that a total energy of pulses transmitted within a preset time be less than a human eye safety threshold; Step S103 further includes a step of increasing the energy of the long-distance detection pulse and decreasing the energy of the short-distance detection pulse when the ranging condition is a long-distance detection condition, and the energy of the short-distance detection pulse is greater than a second energy threshold.

2. 2. The control method of claim 1, wherein the long-distance detection condition includes the target being outside a first distance range, and the second energy threshold is determined based on a detection need for a second distance range, the second distance range being less than or equal to the first distance range.

3. 3. The control method according to claim 2, wherein when the ranging condition is a long-distance detection condition, the energy of the long-distance detection pulse is increased stepwise for each detection until a sum of the energies of the plurality of laser pulses approaches the first energy threshold.

4. 3. The control method according to claim 2, wherein when the ranging condition is the long-distance detection condition, in the next detection, the energy of the long-distance detection pulse is increased so that the sum of the energies of the multiple laser pulses approaches the first energy threshold and the energy of the short-distance detection pulse approaches the second energy threshold.

5. The plurality of laser pulses includes at least one long-distance detection pulse and at least one short-distance detection pulse, and step S103 includes:

2. The control method according to claim 1, further comprising the step of lowering the energy of the long-distance detection pulse and raising the energy of the short-distance detection pulse when the ranging condition is a short-distance detection condition, and the energy of the short-distance detection pulse is equal to or lower than the energy of the long-distance detection pulse in the same transmission.

6. The control method according to claim 5, wherein when the ranging condition is a short-distance detection condition, the long-distance detection pulse and the short-distance detection pulse having similar energy are transmitted in the next detection, and the sum of the energies of the multiple laser pulses approaches the first energy threshold.

7. The control method according to claim 1 , further comprising the step of adjusting the intensity peak or pulse width of the plurality of laser pulses by adjusting the energy distribution of the plurality of laser pulses in a next transmission of the laser radar.

8. The control method of claim 7 , further comprising the step of increasing a pulse peak of the plurality of laser pulses by increasing a maximum drive current / voltage of the plurality of laser pulses.

9. 8. The method of claim 7, further comprising the step of: expanding / shortening the pulse width of the plurality of laser pulses by keeping a driving current / voltage constant and expanding / shortening a transmission time of the plurality of laser pulses.

10. The method of claim 1 , further comprising the step of calculating a distance to the target based on echo information corresponding to the plurality of laser pulses.

11. A transmitting unit for transmitting a laser pulse signal based on pulse coding and a current energy distribution strategy, the laser pulse signal including a plurality of laser pulses for target detection using the pulse coding; a receiving unit configured to receive echo information of the plurality of laser pulses reflected by a target and determine a ranging condition of the target based on the echo information; and a control unit configured to update the energy distribution strategy used during a next transmission of the laser radar based on the ranging condition of the target; the plurality of laser pulses includes at least one long-range detection pulse and at least one short-range detection pulse; the energy distribution strategy is configured to distribute energy among the plurality of laser pulses and control a sum of the energy of the plurality of laser pulses to be less than a first energy threshold, the first energy threshold being determined based on a requirement that a total energy of pulses transmitted within a preset time be less than a human eye safety threshold; The control unit is configured to increase the energy of the long-distance detection pulse and decrease the energy of the short-distance detection pulse when the ranging condition is a long-distance detection condition, and the energy of the short-distance detection pulse is greater than a second energy threshold.

12. 12. The laser radar of claim 11, wherein the long-distance detection condition includes the target being outside a first distance range, the second energy threshold is determined based on a detection need for a second distance range, and the second distance range is equal to or less than the first distance range.

13. The transmitting unit includes at least one laser device, and the laser radar includes:

13. The laser radar according to claim 11 or 12, further comprising a first energy adjusting unit coupled to the at least one laser device and the control unit and configured to adjust, under the control of the control unit, a drive current / voltage of the at least one laser device to adjust pulse peaks of the plurality of laser pulses in a next transmission of the laser radar.

14. The transmitting unit includes at least one laser device, and the laser radar includes:

13. The laser radar according to claim 11 or 12, further comprising a second energy adjusting unit coupled to the at least one laser device and the control unit and configured to adjust, under the control of the control unit, a transmission time of the at least one laser device to adjust pulse widths of the plurality of laser pulses in a next transmission of the laser radar.

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