Lidar sensor and target detection method using the same

Abstract

The present application relates to a kind of laser radar sensor and the target detection method using it, the laser radar sensor, comprising: first emission part, in odd frame, output the laser of first output power, and in even frame, output the laser of second output power, the second output power is lower than the first output power;Second emission part, in odd frame, output the laser of the second output power, and in even frame, output the laser of the first output power;And receiving part, receive the reflected light of the laser output from the first emission part and the second emission part to detect target.

Description

Technical Field

[0001] This invention relates to a lidar sensor and a target detection method using the same, and more specifically, to a lidar sensor capable of high-speed repetitive emission while reducing heat generation and a target detection method using the same. Background Technology

[0002] A vehicle-mounted lidar sensor is a sensor that outputs light to an object and measures the distance between the vehicle and the object based on the reflected signal.

[0003] A lidar sensor consists of a transmitter for outputting laser light and a receiver for receiving laser light reflected from a target. High-power laser light is required to detect targets at long distances or with low reflectivity.

[0004] As for the laser output, the light is output from the internal laser module. The output power is generally determined by the voltage applied to the laser module, but due to limitations such as eye-safety standards, the output power cannot be increased indefinitely.

[0005] Laser emission factors are considered together, including output power and repetition rate in Hz. Repetition rate represents the output cycle of the laser.

[0006] Existing lidar sensors use a single-array transmitter. When using a single-array transmitter, the increased repetition rate causes the transmitter temperature to rise, and the output decreases as the temperature rises, leading to failure.

[0007] Furthermore, when a lidar sensor emits a specified output power, there is a limitation on the dynamic range of reflectivity used to sense targets. That is, when emitting a high-output-power laser to detect distant or low-reflectivity targets, the receiver will saturate when sensing nearby or high-reflectivity targets.

[0008] Furthermore, in the case of a lidar sensor that emits laser light at a specified repetition rate, it can be interfered with by the emitted light of another lidar sensor. When receiving the emitted light from another lidar sensor, the receiver may experience saturation and become unable to sense the target for a certain period of time.

[0009] Therefore, a lidar sensor is needed that can minimize temperature rise while emitting at a high repetition rate, ensure the dynamic range of the receiver, and avoid interference with other lidar sensors.

[0010] Existing technical documents

[0011] Authorized Patent 10-2050632 (November 25, 2019) Multi-channel LiDAR sensor module Summary of the Invention

[0012] Technical problems to be solved

[0013] In view of the above requirements, the technical problem to be solved by the present invention is to provide a lidar sensor that can minimize temperature rise while emitting laser at a high repetition rate.

[0014] In addition, another object of the present invention is to provide a lidar sensor that can prevent interference with other lidar sensors in the vicinity.

[0015] means for solving problems

[0016] The lidar sensor of the present invention, for solving the problems described above, includes: a first transmitting unit that outputs a laser with a first output power in odd-numbered frames and outputs a laser with a second output power in even-numbered frames, wherein the second output power is lower than the first output power; a second transmitting unit that outputs a laser with the second output power in odd-numbered frames and outputs a laser with the first output power in even-numbered frames; and a receiving unit that receives reflected light from the lasers output from the first transmitting unit and the second transmitting unit to detect a target.

[0017] In an embodiment of the present invention, in the odd-numbered frames, the laser with the first output power of the first transmitting unit can precede the laser with the second output power of the second transmitting unit.

[0018] In an embodiment of the present invention, the laser with the first output power of the first emitting unit and the laser with the second output power of the second emitting unit can be output with a predetermined time difference.

[0019] In an embodiment of the present invention, in the even-numbered frames, the laser with the second output power of the first transmitting unit may lag behind the laser with the first output power of the second transmitting unit.

[0020] In an embodiment of the present invention, the laser with the first output power of the first emitting unit and the laser with the second output power of the second emitting unit can be output with a predetermined time difference.

[0021] In an embodiment of the present invention, the reflected light from the laser of the first emitting unit and the reflected light from the laser of the second emitting unit received by the receiving unit can be received at a predetermined interval to distinguish them from lasers emitted by other lidar sensors.

[0022] According to another aspect of the present invention, a target detection method may include: a first step of using a first transmitter to output a laser with a first output power in odd-numbered frames and to output a laser with a second output power in even-numbered frames, wherein the second output power is lower than the first output power; a second step of using a second transmitter to output a laser with the second output power in odd-numbered frames and to output a laser with the first output power in even-numbered frames; and a third step of using a receiver to receive reflected light from the lasers output from the first transmitter and the second transmitter to detect a target.

[0023] In an embodiment of the present invention, in the odd-numbered frames, the laser with the first output power of the first transmitting unit can precede the laser with the second output power of the second transmitting unit.

[0024] In an embodiment of the present invention, the laser with the first output power of the first emitting unit and the laser with the second output power of the second emitting unit can be output with a predetermined time difference.

[0025] In an embodiment of the present invention, in the even-numbered frames, the laser with the second output power of the first transmitting unit may lag behind the laser with the first output power of the second transmitting unit.

[0026] In an embodiment of the present invention, the laser with the first output power of the first emitting unit and the laser with the second output power of the second emitting unit can be output with a predetermined time difference.

[0027] In an embodiment of the present invention, the reflected light from the laser of the first emitting unit and the reflected light from the laser of the second emitting unit received by the receiving unit can be received at a predetermined interval to distinguish them from lasers emitted by other lidar sensors.

[0028] Invention Effects

[0029] The present invention features a dual-array transmitter that alternately distinguishes the output of each transmitter in each frame to minimize heat generation and increase the repetition rate, thereby enabling high-resolution detection of low-reflectivity targets and preventing receiver saturation.

[0030] In addition, the present invention prevents receiver saturation and increases sensing distance by alternately distinguishing the outputs of each transmitter, and has the effect of obtaining target reflectivity information below the reference distance.

[0031] Meanwhile, the present invention controls the output and repetition rate of each of the transmitters in the dual array, thereby preventing interference with other surrounding lidar sensors. Attached Figure Description

[0032] Figure 1 and Figure 2 This is a schematic diagram of the structure of a lidar sensor according to a preferred embodiment of the present invention.

[0033] Figure 3 This is a graph showing the output power curves of the lasers emitted by the first and second emitting sections.

[0034] Figure 4 This is a schematic diagram of the received signal for a high reflectivity target in an odd-numbered frame of the present invention.

[0035] Figure 5 This is a schematic diagram of the received signal for a low reflectivity target in an odd-numbered frame.

[0036] Figure 6 This is a waveform diagram illustrating that the lidar sensor of the present invention can prevent interference with existing lidar sensors.

[0037] Figure 7 It is a graph showing the output of the first transmitter and the output of the second transmitter for each frame.

[0038] Figure 8 This is a comparison curve of laser temperature change between the lidar sensors of the present invention and those of the prior art.

[0039] Explanation of reference numerals in the attached figures

[0040] 10: First launch section; 20: Second launch section

[0041] 30: Receiving Department. Detailed Implementation

[0042] Hereinafter, with reference to the accompanying drawings, the lidar sensor of the present invention and the target detection method using the same will be described in detail.

[0043] The embodiments of the present invention are provided to illustrate the invention more fully to those skilled in the art. The embodiments described below can be modified in various different forms, and the scope of the present invention is not limited to the following embodiments. Rather, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the spirit of the present invention to those skilled in the art.

[0044] The terminology used in this specification is for illustrating specific embodiments and is not intended to limit the invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Furthermore, when used herein, "comprising" and / or "including" designates the presence of the mentioned shapes, numbers, steps, actions, components, elements, and / or combinations thereof, and does not exclude the presence or addition of more than one other shape, number, step, action, component, element, and / or combination thereof. As used herein, the term "and / or" includes any one or more of the listed items and all combinations thereof.

[0045] Although the terms "first," "second," etc., are used in this specification to describe various components, regions, and / or parts, it is clear that these components, components, regions, layers, and / or parts are not limited to these terms. These terms do not imply a particular order, hierarchy, or superiority, but are only used to distinguish one component, region, or part from another. Therefore, without departing from the teachings of this invention, the following "first component, region, or part" may refer to a "second component, region, or part."

[0046] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, which schematically illustrate embodiments of the invention. In the drawings, for example, variations in shape may be expected based on manufacturing techniques and / or tolerances. Therefore, embodiments of the present invention should not be construed as limited to specific shapes within the areas shown in this specification, but should include shape variations such as those caused by manufacturing processes.

[0047] Figure 1 and Figure 2 These are structural diagrams illustrating the configuration state of a lidar sensor according to a preferred embodiment of the present invention.

[0048] Refer to each Figure 1 and Figure 2 The present invention includes a first transmitting unit 10, a second transmitting unit 20, and a receiving unit 30.

[0049] Figure 1 An example is shown where the first transmitting unit 10 and the second transmitting unit 20 are respectively arranged vertically on one side of the receiving unit 30. Figure 2 An example is shown in which the first transmitting unit 10 and the second transmitting unit 20 are respectively arranged on the left and right sides of one side of the receiving unit.

[0050] The first transmitting unit 10 and the second transmitting unit 20 include at least a laser output module and a lens for outputting laser light, and the receiving unit 30 includes at least a lens and a light receiving sensor for receiving laser light.

[0051] This invention can be applied to a structure that uses a scanner to reflect the output laser light from the first transmitting unit 10 and the second transmitting unit 20 onto a predetermined area and scan it. The scanner can also serve to direct the laser light reflected from the target onto the receiving unit 30.

[0052] This invention can also be applied to structures that do not use scanners.

[0053] The invention is characterized in that the output power and repetition rate of the lasers of the first emitting unit 10 and the second emitting unit 20 are different, and in particular, the laser emission output power is output alternately at large and small power levels.

[0054] Figure 3The output power curves of the output lasers from the first emitting unit 10 and the second emitting unit 20 are shown.

[0055] Figure 3 (a) shows the odd-numbered frames. Figure 3 (b) shows the transmit output power in even-numbered frames.

[0056] That is, the lidar sensor of the present invention outputs alternately. Figure 3 The output power shown in (a) and Figure 3 The output power is shown in (b).

[0057] First, in odd-numbered frames, the output power TX1 of the first transmitter 10 is greater than the output power TX2 of the second transmitter 20.

[0058] The laser with a relatively large output power TX1 of the first transmitting unit 10 is output, followed by the laser with a relatively small output power TX2 of the second transmitting unit 20, and the output is repeated at a predetermined repetition rate, taking into account the waiting time of the received signal used for distance sensing calculation.

[0059] That is, the laser output powers TX1 and TX2 of the first transmitting unit 10 and the second transmitting unit 20 are output with a certain time difference.

[0060] Conversely, in even-numbered frames, the output power TX2 of the second transmitter 20 is output with a greater output power than the output power TX1 of the first transmitter 10, and the output sequence is also controlled so that the output power TX2 of the second transmitter 20 is output faster than the output power TX1 of the first transmitter 10.

[0061] Although this control is not shown in the accompanying drawings, it can be performed by a control unit that controls the output of the first transmitter 10 and the second transmitter 20.

[0062] Through this control, the output power of the first transmitter 10 increases in odd-numbered frames and decreases in even-numbered frames, thereby preventing the continuous maintenance of a relatively high transmission output power state and thus reducing temperature rise.

[0063] This also applies to the second launcher 20.

[0064] The lidar sensor obtains the reflectivity information of the target by receiving the intensity of the received signal received by the receiving unit 30. When the receiving unit 30 is set to receive a signal with an intensity of a certain value or higher according to its maximum voltage, it becomes saturated and the reflectivity information cannot be obtained.

[0065] However, in this invention, since the two lasers of the first transmitting unit 10 and the second transmitting unit 20, which have relatively strong output power and relatively weak output power in the same frame, are output and received by the receiving unit 30, saturation and reduction of the maximum sensing distance can be prevented.

[0066] Figure 4 This is a schematic diagram of the received signal for a high reflectivity target in an odd-numbered frame of the present invention.

[0067] Reference Figure 4 In odd-numbered frames, the output power TX1 of the first transmitter 10, which has a relatively strong transmission output power, can be in a saturated state where the received signal does not change with distance within the reference distance. However, above the reference distance, the reflectivity of the light caused by the output power TX1 of the first transmitter 10 is reduced, thereby enabling the detection of high reflectivity targets at the maximum sensing distance.

[0068] Furthermore, since the reflected light caused by the relatively low output power TX2 of the second transmitter 20 exhibits a linearly decreasing waveform without a saturation range within the reference range of the lidar sensor, the reflectivity information of the target can be obtained.

[0069] Conversely, in even-numbered frames, the maximum sensing distance is determined by the output power TX2 of the second transmitter 20, and target detection within a reference distance is performed by the reflected light caused by the output power TX1 of the first transmitter 10, which has a relatively low output power.

[0070] Figure 5 This is a schematic diagram of the received signal for a low reflectivity target in an odd-numbered frame.

[0071] Reference Figure 5 ,and Figure 4 Compared to the waveforms shown and explained, although the maximum sensing distance is reduced and the distance of the saturation range is shortened, the target can still be detected in the saturation range of the first emitting unit 10 by the reflected light caused by the output power TX2 of the second emitting unit 20.

[0072] Thus, by emitting lasers with different output power intensities, the present invention prevents the receiving section 30 from saturating, thereby improving the dynamic range of the reflectivity of the target sensed by the lidar sensor.

[0073] Figure 6 This is a waveform diagram illustrating that the lidar sensor of the present invention can prevent interference with existing lidar sensors.

[0074] Reference Figure 6The present invention receives reflected light of different magnitudes due to two transmit output powers TX1 and TX2 having a predetermined time difference. Since the signal received by the interference receiving unit 30 of the existing lidar sensor can generate a signal at any location and is independent of the target, depending on the location of the lidar that generates the interference signal, a larger or smaller signal can be received compared to the reflected light caused by the output power TX1 of the first transmitter or the reflected light caused by the output power TX2 of the second transmitter.

[0075] Furthermore, since the receiving unit 30 receives the reflected light from the two transmit output powers TX1 and TX2, which are output with a predetermined time difference, the interference signals from other lidar sensors and the received signals from the transmit output powers TX1 and TX2 can be distinguished by using the signal magnitude and interval received by the receiving unit 30.

[0076] Based on this distinction, the distance to the target can be accurately calculated, and interference signals can be eliminated.

[0077] Figure 7 It is a graph showing the output power TX1 of the first transmitter 10 and the output power TX2 of the second transmitter 20 for each of the above frames.

[0078] As described above, in this invention, the output power TX1 of the first emitting unit 10 repeats the relatively high output power range and low output power range for each frame, while the output power TX2 of the second emitting unit 20 repeats the relatively low output power range and high output power range for each frame, so that the temperature of the laser, which is the emitting element of the first emitting unit 10 and the second emitting unit 20, repeatedly increases and decreases, thereby minimizing the temperature increase of the laser.

[0079] This can be seen from Figure 8 The laser temperature change curve confirms that, compared with the transmitter temperature of existing lidar sensors, the lidar sensor of the present invention can maintain a lower temperature.

[0080] Therefore, it is possible to minimize the reduction in transmission output power caused by heat generation at the transmitter of the lidar sensor, and to prevent malfunctions or damage caused by heat generation.

[0081] This invention is not limited to the embodiments described. Those skilled in the art should understand that various modifications and variations can be made without departing from the spirit of this invention.

Claims

1. A lidar sensor, characterized by, comprises: a first emission section that outputs laser light of a first output power in odd-numbered frames and outputs laser light of a second output power in even-numbered frames, the second output power being lower than the first output power; a second emission section that outputs laser light of the second output power in odd-numbered frames and outputs laser light of the first output power in even-numbered frames; and a reception section that receives reflected light of the laser light output from the first emission section and the second emission section to detect a target.

2. The lidar sensor according to claim 1, wherein in the odd-numbered frames, the laser light of the first output power of the first emission section precedes the laser light of the second output power of the second emission section.

3. The lidar sensor according to claim 2, wherein the laser light of the first output power of the first emission section and the laser light of the second output power of the second emission section are output with a prescribed time difference.

4. The lidar sensor according to claim 1, wherein in the even-numbered frames, the laser light of the second output power of the first emission section lags behind the laser light of the first output power of the second emission section.

5. The lidar sensor according to claim 4, wherein the laser light of the first output power of the first emission section and the laser light of the second output power of the second emission section are output with a prescribed time difference.

6. The lidar sensor according to claim 1, wherein the reflected light of the laser light of the first emission section and the reflected light of the laser light of the second emission section received by the reception section are received with a prescribed interval to be distinguished from laser light emitted by other lidar sensors. comprises:

7. A target detection method using a laser radar sensor, characterized by, a first step of outputting laser light of a first output power in odd-numbered frames and outputting laser light of a second output power in even-numbered frames using a first emission section, the second output power being lower than the first output power; a second step of outputting the laser light of the second output power in odd-numbered frames and outputting the laser light of the first output power in even-numbered frames using a second emission section; and a third step of receiving reflected light of the laser light output from the first emission section and the second emission section to detect a target using a reception section.

8. The target detection method using a lidar sensor according to claim 7, wherein in the odd-numbered frames, the laser light of the first output power of the first emission section precedes the laser light of the second output power of the second emission section.

9. The target detection method using a lidar sensor according to claim 8, wherein the laser light of the first output power of the first emission section and the laser light of the second output power of the second emission section are output with a prescribed time difference.

10. The target detection method using a lidar sensor according to claim 7, wherein in the even-numbered frames, the laser light of the second output power of the first emission section lags behind the laser light of the first output power of the second emission section.

11. The target detection method using a lidar sensor according to claim 10, wherein the laser light of the first output power of the first emission section and the laser light of the second output power of the second emission section are output with a prescribed time difference. ​ ​ 12.The target detection method using a laser radar sensor according to claim 7, wherein the reflected light of the laser of the first emission part and the reflected light of the laser of the second emission part received by the reception part are received at a prescribed interval to be distinguished from the laser emitted by other laser radar sensors. 13.A laser radar sensor comprising a plurality of emission parts and a reception part, wherein at least one first emission part of the plurality of emission parts periodically alternately outputs a laser of a first output power and a laser of a second output power which is lower than the first output power, another second emission part of the plurality of emission parts periodically alternately outputs a laser of the second output power and a laser of the first output power, the reception result of the laser of the emission part received by the reception part is distinguished from the laser emitted by other laser radar sensors. 14.The laser radar sensor according to claim 13, wherein the laser emission time of the first emission part and the second emission part are different from each other. 15.The laser radar sensor according to claim 14, wherein the laser of the first emission part and the laser of the second emission part are outputted with a prescribed time difference. 16.The laser radar sensor according to claim 15, wherein the first emission part and the second emission part, the output time is controlled so that the laser of the first output power precedes and the laser of the second output power lags behind.

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