Lidar device and driving method thereof

Abstract

A LiDAR device according to an embodiment of the present invention may comprise: a light emitting unit configured to emit a beam on the basis of a beam profile; a power supply unit; and a light receiving unit configured to receive a beam emitted by the light emitting unit and then reflected from an object, wherein the intensity of the beam emitted by the light emitting unit in the beam profile is determined on the basis of a relative illumination (RI) of the light receiving unit and a distance by which the beam emitted by the light emitting unit travels until reaching the ground.

Description

Lidar device and its driving method

[0001] The present invention relates to a lidar device and a method for driving the same, and more particularly, to a lidar device using a beam profile and a method for driving the same.

[0002] When driving, it's crucial to accurately perceive the surroundings and precisely control the vehicle, such as by stopping to avoid collisions with other vehicles. This requires accurately assessing the locations of surrounding objects.

[0003] At this time, it is important to meaningfully utilize the data collected from the vehicle's sensors, but it can be very cumbersome for users to visually check the collected data one by one.

[0004] Therefore, automatically interpreting and analyzing the collected data is crucial. However, using a standard camera has the limitation of only being able to capture image data from a specific direction. Furthermore, while capturing image data is possible, it doesn't provide information on the distance to the object from the image data.

[0005] Accordingly, methods for obtaining distance information about objects using distance measurement sensors such as LiDAR sensors are being used. LiDAR (Light Detection And Ranging, LiDAR), often called LADAR (Laser Detection And Ranging), ToF (Time of Flight), laser scanner, or laser radar, is a sensing method that detects objects and maps their distances. LiDAR illuminates an object with an optical pulse and then measures the characteristics of the reflected signal.

[0006] Transmitting beams to detect objects using LiDAR can be problematic, as depending on the beam, the object may or may not be detected, and unnecessary power consumption may occur. In particular, transmitting the same beam pattern without considering other characteristics or environmental factors may be inefficient.

[0007] The present invention is intended to solve the above-mentioned problems, and aims to provide a lidar device for detecting an object and a method for driving the same.

[0008] The technical problem to be achieved by the present invention is to provide a lidar device and a driving method thereof that improves the efficiency of a transmission beam by using a beam profile.

[0009] In addition, the technical problems to be solved by the present invention are not limited to the technical problems described above, and other technical problems may exist.

[0010] A lidar device according to one embodiment of the present invention includes a light emitting unit that irradiates a beam based on a beam profile, a power unit, and a light receiving unit that receives a beam reflected from an object by the beam irradiated by the light emitting unit, and the intensity of the beam irradiated by the light emitting unit in the beam profile can be determined based on the RI (Relative Illumination) of the light receiving unit and the distance that the beam irradiated by the light emitting unit reaches the ground.

[0011] In one embodiment of the present invention, the lidar device can determine the intensity of the beam irradiated by the light emitting unit in the beam profile based on the RI of the light receiving unit in the horizontal and vertical directions.

[0012] In one embodiment of the present invention, the lidar device may have an intensity in the vertical direction of the beam irradiated by the light emitting unit in the beam profile that is inversely proportional to the square of the distance the beam irradiated by the light emitting unit reaches to the ground.

[0013] In one embodiment of the present invention, the lidar device may have an intensity in the vertical direction of the beam irradiated by the light emitting unit in the beam profile that is greater than the square of the distance the beam irradiated by the light emitting unit reaches to the ground.

[0014] In one embodiment of the present invention, the distance from the beam irradiated by the light emitting unit to the ground in the beam profile of the lidar device may be within a range of 5 to 20 m.

[0015] In one embodiment of the present invention, the lidar device may set the intensity of the beam irradiated by the light emitting unit in the horizontal direction based on the FWHM (Full Width at Half Maximum) in the beam profile.

[0016] In one embodiment of the present invention, the lidar device may be configured such that the intensity of the beam irradiated by the light emitting unit in the horizontal direction in the beam profile has a FWHM of 90 degrees to 240 degrees.

[0017] In a lidar device according to one embodiment of the present invention, the intensity in the vertical direction of the beam irradiated by the light emitting unit in the beam profile can gradually increase as the diffusion angle of the beam irradiated by the light emitting unit increases.

[0018] In one embodiment of the present invention, the lidar device may have a beam intensity in the horizontal direction irradiated by the light emitting unit in the beam profile that is constant within a predetermined range.

[0019] In a lidar device according to one embodiment of the present invention, the light emitting unit includes a VCSEL (Vertical-cavity surface-emitting laser) and a transmission driver, and the intensity of a beam irradiated by the VCSEL can be controlled by the transmission driver.

[0020] According to an embodiment of the present invention, a lidar device for detecting an object and a method for driving the same can be provided.

[0021] According to an embodiment of the present invention, a lidar device and a driving method thereof that increase the efficiency of a transmission beam by using a beam profile can be provided.

[0022] In addition, the effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0023] FIG. 1 is a drawing showing a transmission beam irradiated from a lidar device placed on a vehicle according to one embodiment.

[0024] Figures 2a and 2b are graphs showing the intensity of the beam according to the direction in which the beam irradiated from the lidar device of Figure 1 spreads and the intensity of the beam in the vertical direction.

[0025] FIG. 3a is a graph showing the RI of a light receiving unit in a lidar device according to an embodiment of the present invention.

[0026] FIG. 3b illustrates a beam profile reflecting the distance that a beam emitted from a light-receiving unit RI and a light-emitting unit of a lidar device reaches the ground according to one embodiment of the present invention.

[0027] FIG. 4 is a graph showing an example of a beam profile (310) in the vertical direction in the horizontal direction in FIG. 3b.

[0028] FIG. 5 is a drawing showing a state in which a lidar device according to one embodiment of the present invention is connected to an electronic device in a vehicle.

[0029] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0030] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0031] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0032] Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0033] In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and / or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0034] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used.

[0035] These terms are intended only to distinguish one component from another, and are not intended to limit the nature, order, or sequence of the component.

[0036] And, when a component is described as being 'connected', 'coupled' or 'connected' to another component, it may include not only cases where the component is directly connected, coupled or connected to the other component, but also cases where the component is 'connected', 'coupled' or 'connected' by another component between the component and the other component.

[0037] Additionally, when described as being formed or arranged "above or below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below", it can include the meaning of a downward direction as well as an upward direction based on one component.

[0038] In one embodiment, a lidar device can scan its surroundings by rotating the sensor using a physical actuator, such as a motor, but can also scan in one direction without a physical actuator. A lidar device that scans in one direction without a physical actuator may be called a solid-state lidar. A lidar device can detect objects from several meters to more than 200 meters away, but may be used to detect long-distance objects rather than close-range objects. A lidar device can not only aim light to a specific area, but if the light is infrared, the wavelength is short, so the spatial resolution can be divided into units of 0.1 degrees, and the features of an object can be described in three dimensions without back-end processing. The azimuth (Field of View, FOV) of a lidar device is an important performance for classifying objects, and can be divided into vertical azimuth and horizontal azimuth.

[0039] In the present disclosure, the term "beam irradiated by a lidar device" may be used interchangeably with "light" or "light beam." The beam irradiated by a lidar device may be referred to as a transmission beam or a transmission beam, and the beam that is reflected by an object and received by the lidar device may be referred to as a reception beam.

[0040] FIG. 1 is a drawing showing a beam irradiated from a lidar device placed on a vehicle according to one embodiment.

[0041] Referring to FIG. 1, a lidar device (20) may be placed or installed on a vehicle (10). The lidar device (20) may be placed on any of the front, rear, or side of the vehicle (10). FIG. 1 illustrates an example in which the lidar device (20) is placed on the rear of the vehicle (10).

[0042] Specifically, in FIG. 1, the lidar device (20) can be placed at a position where the height (101) from the ground is h. The mounting angle (103) of the lidar device (20) means the angle formed by the center of the lidar device (20) in the direction of the ground from a plane horizontal to the ground, and may be α degrees.

[0043] The lidar device (20) can irradiate a beam of the same pattern, and the direction in which the beam irradiated from the lidar device (20) spreads is θ. i, x is the distance reached from the vehicle to the ground i If so, [Mathematical Formula 1] can be established.

[0044] [Mathematical Formula 1]

[0045] tan(θ i +α) = h / x i

[0046] And, the diffusion distance of the beam irradiated from the lidar device (20) is r i If so, [Mathematical Formula 2] can be established.

[0047] [Equation 2]

[0048] ri = sqrt(x i 2 + h 2 )

[0049] According to one embodiment, the spread distance r of the beam irradiated from the lidar device (20) i The range of the beam diffusion distance can be 5 to 20 (m). The range of the beam diffusion distance irradiated from the lidar device (20) may vary depending on the height and mounting angle of the lidar device (20) placed on the vehicle. Therefore, by adjusting the height from the ground, mounting angle, etc. of the lidar device (20) placed on the vehicle, the diffusion distance r of the beam irradiated from the lidar device (20) i The range of the beam can be adjusted. Furthermore, the lidar device (20) adjusts the range of the direction of diffusion of the beam being investigated, thereby adjusting the diffusion distance r of the beam irradiated from the lidar device (20). i The range of the beam can be adjusted. For example, the lidar device (20) irradiates only some beams to adjust the beam spread distance r i You can adjust the range.

[0050] The intensity (I) of the beam irradiated from the lidar device (20) may be inversely proportional to the square of the distance the beam is irradiated. Here, the intensity (I) of the beam may be the intensity of the beam reaching the horizon, and may be the intensity of the beam per unit solid angle.

[0051] Figures 2a and 2b are graphs showing the intensity of the beam according to the direction in which the beam irradiated from the lidar device of Figure 1 spreads and the intensity of the beam in the vertical direction.

[0052] Referring to Fig. 2a, the intensity of a beam emitted from a lidar device may be lower as the diffusion direction is closer to the center, that is, as θ decreases. The intensity (I) of the beam is the intensity of the beam reaching the horizon. If θ increases, the diffusion distance is small and the beam reaches the horizon directly, so the intensity of the beam may be high. On the other hand, if θ decreases, the diffusion distance increases and the beam reaches the horizon far from the vehicle, so the intensity of the beam may be low. For example, if the diffusion direction of the beam is θ2 greater than θ1, the intensity of the beam I1 may be lower than I2.

[0053] Figure 2b is a graph showing the intensity of the beam in the vertical direction among the beam intensities described in Figure 2a. Referring to Figure 2b, the intensity of the beam in the vertical direction is determined by the beam irradiated from the lidar device in a specific direction (θ max ) when spread at maximum (I max ) can be. The intensity of the beam in the vertical direction can be inversely proportional to the square of the spread distance (r) of the beam irradiated from the lidar device. The intensity of the beam in the vertical direction is maximum (I max ) may be a single location, a specific range, or multiple ranges.

[0054] The beam in the horizontal direction can be determined based on the Full Width at Half Maximum (FWHM). The FWHM is the area (or range) where the maximum intensity is half, and according to one embodiment of the present invention, the beam irradiated from the lidar device can be set to have a FWHM of 90 to 240 degrees in the horizontal direction.

[0055] In one embodiment, the lidar device may need to reflect the characteristics of the light receiving unit, as the distribution of the beam being irradiated is important, but the distance to the object is calculated using the beam received when the irradiated beam is reflected from the object. In particular, the RI (Relative Illumination) of the light receiving unit may need to be reflected.

[0056] FIG. 3a is a graph showing the RI of a light receiving unit in a lidar device according to an embodiment of the present invention.

[0057] In Fig. 3a, the x-axis represents the horizontal angle (azimuthal angle), the y-axis represents the vertical angle (elevation angle), and the z-axis represents the RI. Here, the horizontal angle may be the left-right angle of the beam irradiated from the light emitting unit within the lidar device, and the vertical angle may be the up-down angle of the beam irradiated from the light emitting unit within the lidar device. In other words, the vertical angle may be the angle in the direction in which the beam irradiated from the light emitting unit within the lidar device spreads. RI is a relative brightness, and a larger RI value may mean brighter. For example, an RI value of 1 may mean 100% and may mean the brightest.

[0058] Referring to Figure 3a, the light receiving unit can be seen to have a low RI value on the side. The low RI value on the side, both horizontally and vertically, indicates poor light receiving efficiency. Therefore, the lidar device can increase the amount of light, i.e., the amount of beam, in the area where light receiving efficiency is low.

[0059] FIG. 3b illustrates a beam profile reflecting the distance that a beam emitted from a light-receiving unit RI and a light-emitting unit of a lidar device reaches the ground according to one embodiment of the present invention.

[0060] In Fig. 3b, the x-axis represents the horizontal angle (azimuthal angle), the y-axis represents the vertical angle (elevation angle), and the z-axis represents the intensity of the beam. Similarly, in Fig. 3b, the horizontal angle may be the left-right angle of the beam irradiated from the light-emitting unit within the lidar device, and the vertical angle may be the up-down angle of the beam irradiated from the light-emitting unit within the lidar device. In other words, the vertical angle may be the angle in the direction in which the beam irradiated from the light-emitting unit within the lidar device spreads. The unit of the intensity of the beam on the z-axis may be W / sr.

[0061] According to one embodiment, a beam profile may be determined such that the result of dividing the RI of the light receiving portion of the lidar device by the designed beam profile is constant (e.g., 1). Here, the designed beam profile may be a beam profile according to FIG. 2B. Accordingly, FIG. 3B may be a beam profile derived by considering FIG. 3A in the beam profile according to FIG. 2B. Referring to FIG. 3B, the intensity of the beam in the beam profile may not vary significantly along the horizontal direction. However, the intensity of the beam may vary depending on the vertical direction, that is, the direction in which the beam spreads. To show this more clearly, FIG. 4 shows the intensity of the beam along the vertical direction when the horizontal direction is 0 degrees.

[0062] FIG. 4 is a graph showing an example of a beam profile (310) in the vertical direction in the horizontal direction in FIG. 3b.

[0063] In Fig. 4, a solid line (410) represents a beam profile of a beam that a light emitting unit within a lidar device should irradiate, and a dotted line (420) represents one-quarter of the square of the distance that a beam irradiated by a light emitting unit within a lidar device reaches to the ground. Referring to Fig. 4, the intensity of a beam according to a beam profile may always be greater than one-quarter of the square of the distance that a beam irradiated by a light emitting unit within a lidar device reaches to the ground. In addition, the intensity of a beam according to a beam profile may gradually decrease as the diffusion angle of the beam irradiated by the light emitting unit increases.

[0064] FIG. 5 is a drawing showing a state in which a lidar device according to one embodiment of the present invention is connected to an electronic device in a vehicle.

[0065] Although FIG. 5 shows one lidar device connected to an in-vehicle electronic device, the vehicle may include multiple lidar devices, each of which may be connected to an in-vehicle electronic device.

[0066] Referring to FIG. 5, the lidar device (520) may include a power supply unit (530), a light emitting unit (540), and a light receiving unit (560). The lidar device (520) may receive power, control signals, and communication signals from an in-vehicle electronic device (510). The lidar device (520) may also transmit generated signals or data to the in-vehicle electronic device (510).

[0067] The power supply unit (530) can transmit the received power to a component requiring power within the lidar device (520). The power transmitted to the power supply unit (530) may be transmitted from an electronic device (510) within the vehicle, but is not limited thereto. The power supply unit (530) can transmit power according to the power required by the component requiring power within the lidar device (520). In particular, the light emitting unit (540) can irradiate light by adjusting the intensity of light, and thus can request power corresponding thereto from the power supply unit (530). The power supply unit (530) can supply power of the intensity requested by the light emitting unit (540) to the light emitting unit (540).

[0068] The light-emitting unit (540) may include a power source (542), a VCSEL (Vertical-cavity surface-emitting laser) (544), and a transmission driver (546). The power source (542) may supply power to the VCSEL (544). The VCSEL (544), also referred to as a 'vertical cavity surface-emitting laser' or 'VCSEL', may be a type of semiconductor laser diode that emits laser in a vertical direction from its upper surface. The VCSEL (544) may adjust the intensity of the light output by adjusting the current injected through the voltage. The transmission driver (546) may control and drive the VCSEL (544). Specifically, the transmission driver (546) may control the timing at which the VCSEL (544) outputs light. The transmission driver (546) may adjust the output current according to the input voltage to adjust the output light intensity of the VCSEL (544). The transmission driver (546) can accurately supply the required current to the VCSEL (544) to ensure stable operation of the VCSEL (544). In addition, the transmission driver (546) can generate a signal for transmitting data using a technique such as pulse width modulation (PWM), and can perform a temperature compensation function since the performance of the VCSEL (544) can vary depending on temperature. In addition, the transmission driver (546) can protect the VCSEL (544) from situations such as overcurrent, overheating, and short circuit.

[0069] In order to drive the transmitter driver (546), a signal must be received, and this signal can be transmitted from an electronic device (510) within the vehicle. The electronic device (510) within the vehicle is connected to the transmitter driver (546) via an I2C (Inter-Integrated Circuit) to transmit and receive necessary signals. The light emitting unit (540) can be controlled by the electronic device (510) within the vehicle through the transmitter driver (546).

[0070] Separately, the transmitter driver (546) may include an enable pin. Using the enable pin, the transmitter driver (546) may be directly controlled. In the present invention, the in-vehicle electronic device (510) may also be directly connected to the enable pin of the transmitter driver (546) to directly control the light emitting unit (540).

[0071] The light receiving unit (560) can receive light irradiated through the light emitting unit (540) and reflected from an object. The light receiving unit (560) can detect light using a receiving sensor (562).

[0072] According to one embodiment, a clock generation unit (564) may be further included in the light receiving unit (560) to synchronize the light emitting unit (540) and the receiver unit (560). A signal generated through the clock generation unit (564) is input to the receiving sensor (562), and a signal generated in the receiving sensor (562) may be used as a driving signal for the light emitting unit (540). The signal generated in the receiving sensor (562) may be used as a driving signal for the light emitting unit (540) to synchronize the light emitting unit (540) and the receiver unit (560).

[0073] An in-vehicle electronic device (510) can be connected to a lidar device (520) through communication. The in-vehicle electronic device (510) can communicate with a light-emitting unit (540) and a receiver (560) through I2C. The in-vehicle electronic device (510) can control the light-emitting unit (540) and the receiver (560) through I2C communication.

[0074] Although the above description focuses on examples, these are merely examples and do not limit the present invention. Those skilled in the art will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. For example, each component specifically shown in the examples can be modified and implemented. In addition, differences related to such modifications and applications should be construed as being included within the scope of the present invention defined in the appended claims.

Claims

1. A light emitting unit that irradiates a beam based on a beam profile; Power supply; and It includes a light receiving unit that receives a beam reflected from an object by a beam irradiated from the above light emitting unit; A lidar device, wherein the intensity of the beam irradiated by the light emitting unit in the beam profile is determined based on the RI (Relative Illumination) of the light receiving unit and the distance the beam irradiated by the light emitting unit reaches to the ground.

2. In paragraph 1, A lidar device, wherein the intensity of the beam irradiated by the light emitting unit in the beam profile is determined based on the RI of the light receiving unit in the horizontal and vertical directions.

3. In paragraph 1, A lidar device in which the intensity of the beam irradiated by the light emitting unit in the vertical direction in the above beam profile is inversely proportional to the square of the distance the beam irradiated by the light emitting unit reaches to the ground.

4. In paragraph 1, A lidar device in which the intensity in the vertical direction of the beam irradiated by the light emitting unit in the above beam profile is greater than the square of the distance the beam irradiated by the light emitting unit reaches to the ground.

5. In paragraph 1, A lidar device, wherein the distance to the ground of the beam irradiated by the light emitting unit in the above beam profile is within a range of 5 to 20 m.

6. In paragraph 1, A lidar device in which the intensity of the beam irradiated by the light emitting unit in the horizontal direction in the above beam profile is set based on the FWHM (Full Width at Half Maximum).

7. In paragraph 6, A lidar device in which the intensity of the beam irradiated by the light emitting unit in the horizontal direction in the above beam profile is set so that the FWHM is from 90 degrees to 240 degrees.

8. In paragraph 1, A lidar device in which the intensity in the vertical direction of the beam irradiated by the light emitting unit in the above beam profile gradually decreases as the diffusion angle of the beam irradiated by the light emitting unit increases.

9. In paragraph 1, A lidar device in which the intensity of the beam irradiated by the light emitting unit in the horizontal direction in the above beam profile is constant within a set range.

10. In paragraph 1, The above light-emitting unit includes a VCSEL (Vertical-cavity surface-emitting laser) and a transmission driver, A lidar device in which the intensity of the beam irradiated by the VCSEL is controlled by the above-mentioned transmitting driver.

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