Optical distance measuring device

Abstract

An optical distance measuring device is arranged on the top of a vehicle running on a road surface and comprises an array type light source. The arrayed light source has a field of view in a direction perpendicular to the road surface and includes a plurality of light sources including a plurality of near light sources and a plurality of far light sources. The field of view comprises a first field of view and a second field of view, the first field of view is a range of an included angle larger than or equal to 6.5 degrees of rotation of a reference optical axis of the optical distance measuring device towards the road surface, and the first field of view is only provided by the proximity measuring light sources of the light sources in the array type light source. Thus, the present invention can prevent ghosting and can improve the comfort and safety of an autonomous vehicle.

Description

Technical Field

[0001] This invention relates to an optical ranging device, and more particularly to an optical ranging device used in vehicles. Background Technology

[0002] LiDAR (Light Detection and Ranging) systems employ an optical ranging architecture that measures distance and maps three-dimensional objects by emitting a light beam and measuring its time of flight (TOF) – the time it takes for light to travel from emission to reception. This technology can accurately create three-dimensional images of the environment or objects and is widely used in vehicles; for example, LiDAR can be used in autonomous vehicles for environmental perception. Generally, to ensure sufficient reaction time to unexpected situations while vehicles are traveling at high speeds, optical ranging devices are mostly required to observe objects at a distance of approximately 200 to 300 meters (or even further), and LiDAR systems are developed to improve this range.

[0003] Figure 1 This is a schematic diagram of an optical rangefinder 100. (As shown...) Figure 1 As shown, the optical ranging device 100 includes a transmitting module 110 and a detecting module 120. The transmitting module 110 can be an array of light sources, such as multiple light sources 110A, 110B, 110C, and 110D arranged in an array. The detecting module 120 can be an array of detectors corresponding to the light sources, such as multiple detectors 120A, 120B, 120C, and 120D arranged in an array. Typically, each detector corresponds to a light source to form a detection channel. For example, the detection light LA ​​emitted by light source 110A is collimated and shaped by the first mirror group 130, and then emitted from the optical rangefinder 100 through the rotating mirror 140. The part of the light scattered by the detection light LA ​​onto the object 2 forms the echo light RA. After the echo light RA returns to the optical rangefinder 100, it is filtered and shaped by the second mirror group (not shown) and then received by the detector 120A. The optical rangefinder 100 can then use the time of flight of the detection light LA ​​and the echo light RA to calculate the distance between the object 2 and the optical rangefinder 100. Figure 1 The optical ranging device 100 uses the rotation of the rotating mirror 140 to make the probe light LA ​​scan the field of view (FOV), hence it is also called a scanning ranging device.

[0004] However, due to the need for system miniaturization, the layout space for the aforementioned array-arranged light sources 110A, 110B, 110C, 110D and detectors 120A, 120B, 120C, 120D becomes very limited. Therefore, isolating the signals between the light sources is crucial; otherwise, cross-talk between the detection channels can easily occur. For example, if one detection channel receives an echo signal from the field of view of another detection channel, it will cause an echo signal to appear at the original object's location in the detection result (e.g., a point cloud image). This phenomenon is known as "ghosting."

[0005] More specifically, such as Figure 2 A simplified schematic diagram of the optical ranging device 100 shows that when light emitted from the light source 110C scans the road surface 4, the light is easily reflected, diffused, and / or scattered by the road surface 4, and then reflected back to the detection module 120 by objects 2 near the road surface 4 (e.g., cones or construction signs). Because the light has been reflected multiple times, the echo light may be received by a non-preset detector 120D. Therefore, the optical ranging device 100 will judge that there is an object in the detection channel formed by the light source 110D and the detector 120D, resulting in a false obstacle signal, which is the aforementioned ghosting. For example, when a vehicle is driving on a city road, the road conditions are more complex and changeable. If a highly reflective object suddenly appears at close range (e.g., the license plate or sign of a vehicle quickly cutting into the lane at an intersection ahead) or the road surface 4 diffuses the light, this echo light is also easily misjudged, resulting in ghosting (noise) in the point cloud map. In autonomous driving scenarios, near-field noise can cause the vehicle to brake frequently, causing discomfort to passengers and hindering the system's ability to identify real objects on the road ahead, thus endangering road safety.

[0006] Chinese Patent No. CN118235061A (hereinafter referred to as CN061) discloses a ranging LiDAR system that combines two ranging modules with different mechanisms, such as a scanning LiDAR module and a non-scanning ranging module. CN061 applies the two modules to ranging from different perspectives. For example, the non-scanning ranging module is used to detect objects about 5 meters away from the vehicle, while the scanning LiDAR module is used to sense objects 200 meters away from the vehicle. However, for the vehicle control system, such combined use will create a computational burden on the system. This is because each ranging module has its own coordinate system, and the vehicle also has a coordinate system for its driving position. Therefore, the vehicle control system needs to calibrate, convert, and combine various different coordinate systems in order to integrate road condition information for evaluating driving behavior. In other words, CN061's dual-module ranging method will increase the computational burden on the vehicle control system and the possibility of misjudgment. On the other hand, CN061 uses a non-scanning ranging module to determine whether there are objects on the road surface at close range, which still does not solve the ghosting problem of the aforementioned scanning LiDAR module. Summary of the Invention

[0007] The main objective of this invention is to provide an optical ranging device that can prevent ghosting and improve the comfort and safety of autonomous vehicles.

[0008] Another objective of this invention is to provide an optical ranging device having multiple linearly arranged light sources. In a specific field of view, only the near-range light source is used for detection operations, in order to avoid signal interference caused by the high-energy light emitted by the far-range light source being reflected / scattered by nearby high-reflectivity objects and easily misreceived by other detection channels.

[0009] Another objective of this invention is to provide an optical ranging device suitable for self-driving vehicles in urban areas, so as to avoid abnormal driving behavior caused by ghosting signals from nearby high-reflectivity objects, while also complying with regulatory requirements.

[0010] To achieve the aforementioned objectives, the present invention provides an optical ranging device mounted on the top of a vehicle traveling on a road surface. The optical ranging device includes an array of light sources. The array of light sources has a field of view perpendicular to the road surface and includes multiple light sources, including multiple proximity light sources and multiple distance light sources. The field of view includes a first field of view and a second field of view. The first field of view is defined as the angle range within which a reference optical axis of the optical ranging device is rotated toward the road surface by a factor greater than or equal to 6.5°. This first field of view is provided solely by the proximity light sources within the array of light sources.

[0011] In some embodiments, the first field of view is the range of angles within which the reference optical axis of the optical ranging device is rotated toward the road surface by a factor greater than or equal to 11.4°.

[0012] In some embodiments, the light sources are sequentially designated as light source #1, light source #2, light source #3 to light source #x in a direction perpendicular to or not parallel to the road surface. Light source #1 is furthest from the top of the vehicle, and light source #x is closest to the top of the vehicle. The field of view of light source #n covers an angle of 6.5°, where x is a positive integer greater than 1 and n is a positive integer greater than 1 and less than or equal to x. Light sources #n to #x are proximity light sources. Preferably, light sources #1 to #n-1 are distance light sources, or a combination of distance and proximity light sources. Preferably, light sources #1, #2, #3 to #x provide multiple single-line light sources for scanning in the field of view. These multiple single-line light sources are reflected by a rotating mirror for scanning the field of view in a direction parallel to the road surface.

[0013] In some embodiments, the proximity light source and the distance light source provide multiple single line light sources for scanning in the field of view, and these multiple single line light sources are used for scanning the field of view in a direction parallel to the road surface by reflection from a rotating mirror.

[0014] In some embodiments, the proximity light source and the distance light source are arranged in an aligned or staggered linear array.

[0015] In some embodiments, the wavelengths of the proximity light source and / or the distance light source are 905 nm, 940 nm, or 1550 nm.

[0016] In some embodiments, the array light source includes a separate first light source array module and a second light source array module.

[0017] In some embodiments, the first light source array module and the second light source array module each have M1 light sources and M2 light sources. The M1 light sources emit M1 light signals, and the M2 light sources emit M2 light signals. The M1 light signals are split into S1 light signals after passing through a beam splitter, and the M2 light signals are split into S2 light signals after passing through the beam splitter, wherein S1 is greater than M1, and S2 is greater than M2. The S1 light signals and the S2 light signals are perpendicular or non-parallel. The detector beams are sequentially arranged along the road surface as follows: Detector Beam 1, Detector Beam 2, Detector Beam 3 to Detector Beam x. Detector Beam 1 is furthest from the top of the vehicle, and Detector Beam x is closest to the top of the vehicle. The field of view of Detector Beam n covers an angle of 6.5°, where x is a positive integer greater than 1 and n is a positive integer greater than 1 and less than or equal to x. The light sources emitting Detector Beams n to x from the M1 and M2 light sources are proximity light sources. Preferably, the light sources emitting Detector Beams n to (n-1) from the M1 and M2 light sources are distance light sources, or a combination of distance and proximity light sources. Preferably, Light Source 1, Light Source 2, Light Source 3 to Detector Beam x provide multiple single-line light sources for scanning in the field of view. These multiple single-line light sources are reflected by a rotating mirror for scanning the field of view in a direction parallel to the road surface.

[0018] The advantages of this invention are that it can prevent ghosting and improve the comfort and safety of autonomous vehicles. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an optical rangefinder.

[0020] Figure 2 A simplified schematic diagram of an optical rangefinder;

[0021] Figure 3 Drawing or including one or more exemplary embodiments of the optical ranging device of the present invention on the roof of a vehicle;

[0022] Figure 4A A schematic diagram of the optical ranging device according to an embodiment of the present invention is shown;

[0023] Figure 4B A schematic diagram of another embodiment of the transmitting module of the present invention is shown;

[0024] Figure 5 Draw the relationship between the transmitting module of the first embodiment of the present invention and the aforementioned field of view;

[0025] Figure 6AThe transmitting module of the optical ranging device according to the second embodiment of the present invention is shown, mainly illustrating the relationship between the transmitting module and the aforementioned field of view;

[0026] Figure 6B draw Figure 6A An enlarged schematic diagram of region A.

[0027] Explanation of reference numerals in the attached figures

[0028] 1: Optical ranging device

[0029] 2: Object

[0030] 3: Vehicles

[0031] 4: Road surface

[0032] 10: Shell

[0033] 20: Windows

[0034] 30, 30A: Transmission Module

[0035] 31A, 31B, 31C, 31D: Light source

[0036] 32: First Light Source Array Module

[0037] 321A, 321B, 321C, 321D: Light source

[0038] 33: Second Light Source Array Module

[0039] 331A, 331B, 331C, 331D: Light source

[0040] 40: Rotating Mirror

[0041] 41: Shaft

[0042] 50: Detection Module

[0043] 60: First Shot Group

[0044] 61: First collimating lens

[0045] 62: Second collimating lens

[0046] 63: Reflector

[0047] 64: Spectrometer

[0048] 70: Reflector

[0049] 80: Second Shot Group

[0050] 90: Vertical total field of view

[0051] 91: First zone field of view

[0052] 92: Second zone field of view

[0053] 100: Optical ranging device

[0054] 110: Transmission Module

[0055] 110A, 110B, 110C, 110D: Light source

[0056] 120: Detection Module

[0057] 120A, 120B, 120C, 120D: Detectors

[0058] 130: First Shot

[0059] 140: Rotating Mirror

[0060] D: Forward probe distance

[0061] L: Reference optical axis

[0062] LA, LA1~LA96: Probe light

[0063] RA: Echo

[0064] θ: included angle Detailed Implementation

[0065] The embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and component symbols, so that those skilled in the art can implement them after studying this specification.

[0066] Figure 3 The invention describes the mapping of one or more exemplary optical ranging devices 1, as shown in the embodiments of the invention, mounted on the roof of vehicle 3. Vehicle 3 can be any vehicle as defined by the Society of Automotive Engineers (SAE) as a non-automated vehicle, partially automated (driver-assisted) vehicle, conditionally automated vehicle, highly automated vehicle, or fully automated vehicle. For example, a partially automated vehicle can perform certain driving functions without a human driver operating the steering wheel / pedal, such as lane keeping and / or lane changing, automatic emergency braking, etc.; similarly, a fully automated vehicle can operate autonomously in any situation.

[0067] LiDAR is typically a sensing device installed on the aforementioned vehicle 3 to sense the distance and / or position of objects in front. In one embodiment, such as Figure 3As shown, vehicle 3 may include an optical ranging device 1, a LiDAR system, positioned at the highest point of the vehicle body (e.g., on the roof); for example, the LiDAR system positioned on the roof performs a 360-degree or any-angle scan. Unless otherwise specified, "scanning" as used herein refers to the LiDAR system emitting one or more beams in one or more directions (e.g., horizontal and / or vertical) to scan objects within the field of view (FOV). This paper primarily addresses the signal interference problem encountered by scanning LiDAR, not scanning-type LiDAR, such as flash LiDAR, which is not covered by the architecture discussed in this solution.

[0068] Figure 4A A schematic diagram of the structure of the optical ranging device 1 according to an embodiment of the present invention is shown. Figure 4B A schematic diagram of another embodiment of the transmitting module 30 of the present invention is shown. For example... Figure 4A As shown, the first embodiment of the present invention provides an optical ranging device 1, including a housing 10, a window 20, a transmitting module 30, a rotating mirror 40, a detection module 50, a first mirror group 60, a reflecting mirror 70, and a second mirror group 80. The housing 10 and the window 20 are assembled to form a space accommodating the aforementioned modules. The optical ranging device 1 of this embodiment can be, for example, a forward-facing lidar, as schematically shown in the figure. The window 20 faces forward (e.g., the direction of vehicle travel), and the detection light LA ​​is guided outward from the window 20 for scanning and detection. The transmitting module 30 includes an array of light sources, such as multiple light sources arranged in an array. Exemplary light source arrays can be 1×16, 1×32, 1×64, 1×128, etc. (The figures are simplified for brevity.) Figure 4A Only four light sources, 31A, 31B, 31C, and 31D, are drawn. In this embodiment, the array arrangement means that light sources 31A, 31B, 31C, and 31D are arranged substantially along the direction Z (also known as the vertical direction or Z-axis) perpendicular to the ground. That is, the number "1" in the aforementioned array formula represents that the light sources are set in a row in the direction Z to become linear light sources. Figure 4A When light sources 31A, 31B, 31C, and 31D emit a single linear light signal, they can scan the object in the Z direction. It is worth noting that the aforementioned light sources 31A, 31B, 31C, and 31D can be arranged in an alternating manner (e.g., ...). Figure 4B This staggered arrangement is also considered a linear arrangement in this paper because, for the speed of light, the left-right stagger distance between light sources 31A, 31B, 31C, and 31D is negligible. In other words, for the detection module 50, the position of light source 31B is irrelevant regardless of whether it is aligned with light sources 31A, 31B, 31C, and 31D (e.g., ...). Figure 4A Or staggered by a certain distance (such as...) Figure 4BThe interleaved light sources shown (31A, 31B, 31C, and 31D) can all be considered as being aligned with each other on the Z-axis. For example, a linear array whose length in one dimension is much greater than the length in another dimension, such as greater than or equal to 3, 5, or 10 times, can be considered a linear array arrangement. Figure 4B In other words, the length of the transmitting module 30 in the Z-axis direction is greater than or equal to 3, 5, or 10 times the length of the transmitting module 30 in the X-axis direction.

[0069] The detection module 50 includes an array of detectors (not shown), which are configured in a manner corresponding to an array of light sources, such as the arrangement of the detectors, the adjacent distance, the sensing angle, etc. The configuration of the detection module 50 in this paper can be arranged using any known technology, and will not be described in detail here.

[0070] like Figure 4A As shown, the light signals output by light sources 31A, 31B, 31C, and 31D are adjusted (e.g., shaped or collimated) by the first mirror group 60, and then emitted through the viewing window 20 towards the outside of the optical ranging device 1 via the rotating mirror 40 to form the probe light LA. In this embodiment, the rotating mirror 40 is connected to a driving component such as a motor and rotates continuously. Figure 4A The image is drawn as a one-dimensional rotation on a horizontal plane (i.e., the plane formed by the X and Y axes, which is essentially parallel to the ground). Figure 4A The rotating mirror 40 also schematically rotates clockwise along the axis 41 as indicated by the arrow, thereby enabling the probe light LA ​​to scan the XY plane to detect objects in the horizontal field of view (relative to the vertical field of view). It is understood that... Figure 4A The LiDAR system on display uses a linear array of light emitting modules 30 arranged in the column direction (Z-axis) to achieve vertical field-of-view scanning, and a rotating mirror 40 to achieve horizontal field-of-view scanning through one-dimensional rotation in the lateral direction, so as to achieve scanning of the space in front of the vehicle 3. By scanning and detecting each time the probe light LA ​​scans in the vertical and horizontal directions, a detection result can be obtained, such as a point cloud map of one frame. This point cloud map can cover the total field of view of both the horizontal and vertical fields of view. However, this invention mainly focuses on the vertical field of view.

[0071] Please cooperate again. Figure 4A The probe light LA ​​is reflected and diffused by an object (not shown) to form an echo light RA. The echo light RA enters the optical ranging device 1 through the viewing window 20, and after passing through the rotating mirror 40, the reflecting mirror 70, and the second mirror group 80 (e.g., shaping or focusing), it is received by the detection module 50. It is understandable that... Figure 4AAn exemplary diagram illustrates the detection channel formed by light source 31B and its corresponding detector. In other words, multiple light sources and multiple detectors can correspond to form multiple detection channels, each corresponding to a different field of view. The field of view of the detection channel in this embodiment can be described using light sources. For example, the vertical field of view of the optical ranging device 1 of this invention is +25° to -25°, with the horizontal direction of the installation height of the optical ranging device 1 of this invention as 0° (i.e., ...). Figure 3 As shown in the horizontal direction L), the upward counterclockwise tilt angle is negative, and the downward clockwise tilt angle is positive. Assuming the vertical angular resolution of each light source in this embodiment is 0.2°, the light emitted by the highest position light source 31A in the light source array is shaped by a lens (group) and emitted towards -25°. Therefore, the beam of light source 31A corresponds to a vertical field of view of -25° to -24.8°; the beam of light source 31B, located at the second highest position in the light source array, corresponds to a vertical field of view of -24.8° to -24.6°, and so on up to a field of view of +25°. It is worth noting that regardless of whether light sources 31A, 31B, 31C, and 31D are aligned (e.g., ...), the vertical angular resolution of each light source in this embodiment is 0.2°. Figure 4A ) or staggered arrangement (such as Figure 4B Each light source's vertical field of view in direction Z (e.g., the vertical direction or the Z-axis) can satisfy the above-described conditions. Furthermore, each vertical field of view can be overlapping or non-overlapping, which allows the probe light LA ​​to have a slight divergence angle.

[0072] In some embodiments, the number of light sources 31A, 31B, 31C, 31D and detectors forming the detection channel is not limited. Preferably, the light sources 31A, 31B, 31C, 31D and their corresponding number of detectors can form a detection channel. When the light sources and detectors belonging to the same detection channel are activated and operated respectively, the detection channel is in operation, thereby enabling the detection of objects.

[0073] In some embodiments, the emitting module 30 may be a vertical cavity surface emitting laser (VCSEL) or an edge emitting laser (EEL). The laser source is driven to emit the probe light LA ​​by applying a driving current to the emitting module 30.

[0074] In some embodiments, the detection module 50 may be an avalanche photodiode (APD) or a silicon photomultiplier (SiPM). A bias voltage (V0) is applied to the detector of the avalanche photodiode or SiPM. bias To activate the detection module 50 to detect the echo light RA.

[0075] It should be noted that the rotating mirror 40, the first mirror group 60, the reflecting mirror 70, and the second mirror group 80 in the first embodiment of the present invention can all be selected from conventional optical devices, which will not be described in detail here. Furthermore, suitable optical mirror groups can be added to the optical path as needed, and are not limited to this embodiment. Figure 4A The optical path shown is merely an example and is not actually limited to the optical path structure of the optical ranging device 1 of the present invention.

[0076] Please return Figure 3 This diagram shows an optical ranging device 1 installed on the roof of a vehicle 3 according to an embodiment of the present invention. The present invention provides a scanning LiDAR system with an array light source, which has angular selectivity in the array light source to solve the aforementioned ghosting problem. Figure 3 As shown, the vertical total field of view 90 of the optical ranging device 1 of the present invention can be substantially divided into a first field of view (low-angle field of view) 91 and a second field of view (forward detection field of view) 92. The first field of view (low-angle field of view) 91 is only handled by the proximity light source. Due to the increasing emphasis placed on autonomous vehicle applications in various countries, many regulations related to autonomous vehicles have recently been announced. The embodiments of the present invention also follow the regulations / rules of the mainstream autonomous vehicle market to manufacture the optical ranging device 1 of the present invention, so as to simultaneously meet regulatory requirements and solve technical signal interference problems.

[0077] Specifically, in this embodiment of the invention, the optical ranging device 1 is installed on the top of the vehicle 3 traveling on the road 4. According to statistics from the vehicle database, the height of a typical vehicle is between 1.2 and 1.98 meters. Therefore, the height H of the vehicle 3 in this embodiment is calculated using an average value of 1.58 meters. Furthermore, based on US experiments with Automatic Emergency Braking Systems (AEB), the time to collision (TTC) for the vehicle 3 is set at 5 seconds. This means that the vehicle 3 must not collide with any vehicle (including objects, pedestrians, etc.) in front within 5 seconds while in motion. Based on the aforementioned collision time, this embodiment of the invention calculates the minimum forward detection distance D of the optical ranging device 1. In other words, when the vehicle 3 is moving at a constant speed, the optical ranging device 1 can continuously sense objects within the minimum forward detection distance D ahead, preventing a collision for the vehicle 3. According to the distance formula for constant-speed motion: D = V × 5sec; however, for autonomous driving systems, driving in cities is relatively difficult compared to highways, with far greater complexity and uncertainty. For example, there is no separation of pedestrians and vehicles, unclear lane markings, a variety of traffic lights, encounters with accidents ahead, and illegal parking, etc. Therefore, this embodiment of the invention is mainly designed for autonomous driving in cities, i.e., at a low speed (e.g., 10km / hr), but requiring constant monitoring of objects ahead. Based on the foregoing, the minimum forward distance D in this embodiment of the invention is calculated as D = 10km / hr × 5sec, resulting in D = 13.8m. Using trigonometric functions, the tilt angle θ = 6.5° can then be derived. In other words, from... Figure 4A From the horizontal plane at the same height as the optical ranging device 1 of the present invention (i.e., Figure 4A The range of angles θ within which the 0° reference optical axis (L) is rotated toward the road surface 4 by a factor of 6.5° or greater (the direction of rotation has been specified, so no sign is indicated to avoid confusion) constitutes the first field of view 91 (i.e., the low-angle field of view). The array light source includes multiple proximity light sources and multiple distance light sources. The first field of view 91 is provided solely by the proximity light sources in the array light source. Therefore, this invention can prevent ghosting and improve the comfort and safety of the autonomous vehicle 3.

[0078] Figure 5 The relationship between the transmitting module 30 of the first embodiment of the present invention and the aforementioned field of view is shown in the diagram. Figure 5 The constructed transmitting module 30 has light sources 31A, 31B, 31C, and 31D, each with a field of view of 4°, and a total viewing angle of -6° to +10° along the Z-axis. Figure 5As shown, the center of light source 31B corresponds to the 0° reference optical axis L. Therefore, from the perspective of field of view, the combined field of view of the lower half of light source 31B and the field of view of light source 31C will cover a 6° field of view range (i.e., 0° to +6°). According to the calculations above, a field of view range greater than or equal to 6.5° (the angle rotated clockwise around the 0° reference optical axis L) is only covered by the proximity light source. Therefore, light source 31D must be a proximity light source, and its field of view range (i.e., +6° to +10°) is equivalent to... Figure 3 The first field of view 91 is plotted; and light sources 31A, 31B, and 31C can be distance measuring light sources, or combinations of distance measuring and proximity measuring light sources, and their respective field of view ranges (i.e., -6° to +6°) are equivalent to Figure 3 The second field of view 92 is plotted. In this embodiment, the included angle θ = 6° to 6.5° (the angle rotated clockwise around the 0° reference optical axis L) is covered by the light source 31D (i.e., the proximity light source), but this included angle field of view is not the focus of this invention. It is worth noting that the field of view angle referred to herein refers to the coverage angle of the probe light LA ​​after passing through optical devices (such as the first mirror group 60, the rotating mirror 40, etc., but not limited to this), and finally emitted through the window 20. For the sake of simplicity, Figure 5 Only the light source and the first mirror group 60 are shown. In another embodiment, other proximity light sources may be included to cover a larger low-angle field of view, for example, more proximity light sources may be arranged below the light source 31D to cover a field of view of +10° to +25° (rotated clockwise around the 0° reference optical axis L); similarly, other distance light sources may be included to cover a larger forward detection field of view, for example, more distance light sources may be arranged above the light source 31D to cover a field of view of -6° to -25° (rotated counterclockwise around the 0° reference optical axis L).

[0079] In this embodiment, the maximum ranging range of the near-measuring light source is less than approximately 100m, such as 90m, 70m, 50m, 25m, 10m, 5m, etc.; the minimum ranging range of the far-measuring light source is greater than approximately 200m, such as 230m, 250m, 260m, 300m, 350m, 400m, etc., and the difference in ranging can be mainly controlled by the current applied to the aforementioned light-emitting chip. In one embodiment, chips with different light-emitting powers can be selected to distinguish between the near-measuring light source and the far-measuring light source. Taking a vertical-cavity surface-emitting laser (VCSEL) light source as an example, the average optical power per aperture of the near-measuring light source (under nanosecond (ns) pulse conditions) is less than 10mW, such as 0.1mW, 0.5mW, 1mW, 5mW, etc., while the average optical power per aperture of the far-measuring light source (under nanosecond (ns) pulse conditions) is greater than 10mW, such as 15mW, 20mW, 30mW, 50mW, 100mW, etc. In another embodiment, taking a vertical-cavity surface-emitting laser array (VCSELarray) light source as an example, the peak power of the proximity light source (under 10 kHz / 10 nanosecond (ns) short pulse test conditions) is less than 100 W, for example, 8 W, 10 W, 20 mW, 50 W, etc., while the peak power of the distance light source (under 10 kHz / 10 nanosecond (ns) short pulse test conditions) is greater than 100 W, for example, 110 W, 120 W, 150 W, 200 W, 1000 W, etc. As mentioned above, since the low-angle field of view (i.e., the first zone field of view 91) is detected by the proximity light source, the probe light LA ​​emitted towards the ground is a low-energy beam. Therefore, the probability of the echo reflected by highly reflective objects being misreceived by detectors in other detection channels can be reduced, thus reducing the ghosting problem caused by the aforementioned misreceived signals.

[0080] In this embodiment, the transmitting module 30 also includes a control module (not shown), such as a Field Programmable Gate Array (FPGA), Microcontroller Unit (MCU), System-on-Chip (SoC), or Application-Specific Integrated Circuit (ASIC), which can be used to control the light sources 31A, 31B, 31C, and 31D to emit light. This paper proposes a solution to the interference of line light sources, so the control module essentially controls the light sources 31A, 31B, 31C, and 31D to emit light "simultaneously". For example, the control module emits a first pulse at a first time point to make all four (i.e., all light sources) emit light simultaneously for the first scan; then, the control module emits a second pulse at a second time point to make all four (i.e., all light sources) emit light simultaneously for the second scan, and so on, to perform multiple scans of the object in front of the vehicle. As those skilled in the art will understand, the control module driving light sources 31A, 31B, 31C, and 31D to emit light in a sequential manner is also considered as "simultaneous" emission, because the interval between emission times is usually quite short, such as a few microseconds or even less, and is negligible. For example, if the control module emits a first pulse at a first time point to make light sources 31A and 31C emit light simultaneously, and emits a second pulse at a second time point to make light sources 31B and 31D emit light, since the interval between the first and second time points is negligible, the first scan is still considered to be performed by light signals emitted "simultaneously" by light sources 31A, 31B, 31C, and 31D; then, the above steps are repeated for the second and third scans. In other words, the proximity light source responsible for the low-angle field of view and the light source responsible for the area outside the low-angle field of view (such as the distance light source) in this embodiment of the invention emit a single linear light and repeat it multiple times to perform the scanning operation.

[0081] In one embodiment, the light source of each emitting module 30 is activated by a drive signal provided by a control module, which can be generated by a drive circuit in the control module. For example, the drive signal may include one or more pulse signals, such as periodic pulse signals, and the emission signal of the light source will correspondingly include one or more pulse light signals. Generally, the drive signal may include the following exemplary features: wavelength, pulse width, number of pulses, pulse peak value, and pulse interval, etc.

[0082] In summary, the light sources in the transmitting module 30 of the optical ranging device 1 of the first embodiment of the present invention can be arranged as follows: the light sources are arranged sequentially in a direction substantially perpendicular to or not parallel to the road surface 4 as light source 1 (e.g., light source 31A), light source 2 (e.g., light source 31B), light source 3 (e.g., light source 31C) to light source x (not shown in the figure, but should be understood as light sources arranged continuously below light source 31D), and the light source farthest from the top of the vehicle 3 is light source 1 (e.g., light source 31A), and the light source closest to the top of the vehicle 3 is light source x (e.g., light source 31C). Figure 5 The schematic diagram is shown, x = 4). The field of view of the nth light source covers an angle of 6.5°. Light sources n through x are proximity light sources, meaning that... Figure 5 In this embodiment, the field of view of light source #4 covers an angle of 6.5°, therefore light source #4 is a proximity light source (in this embodiment, n = x = 4); in addition, light sources #1 to #3 can be distance light sources, or a combination of distance light sources and proximity light sources. In another embodiment, when x = 7 (that is, a total of seven light sources), then light sources #4 to #7 are proximity light sources; similarly, light sources #1 to #3 can be distance light sources, or a combination of distance light sources and proximity light sources.

[0083] Figure 6A The optical ranging device 1 of the second embodiment of the present invention is shown, mainly illustrating the relationship between the transmitting module 30A and the aforementioned field of view. Figure 6B draw Figure 6AAn enlarged schematic diagram of region A. In this embodiment, the emitting module 30 includes a substantially separate first light source array module 32 and a second light source array module 33. Each module contains four light sources arranged in a linear array: 321A, 321B, 321C, 321D and 331A, 331B, 331C, 331D. The first and second light source array modules 32 and 33 can be considered mutually separate, both in terms of optical path and physical circuit arrangement (e.g., mounted on different PCBs). The first mirror group 60 includes a first collimating lens 61 corresponding to the first light source array module 32, a second collimating lens 62 corresponding to the second light source array module 33, a reflector 63, and a beam splitter 64. Specifically, the four beams emitted by the first light source array module 32 are adjusted (e.g., shaped or collimated) by the first collimating lens 61 before being output to the beam splitter 64. Similarly, the four beams emitted by the second light source array module 33 are adjusted (e.g., shaped or collimated) by the second collimating lens 62 before being output to the beam splitter 64 via the reflector 63. The beam splitter 64 splits the eight beams emitted by the first and second light source array modules 32 and 33 into ninety-six probe beams LA1 to LA96. In short, the light signal emitted by one light source is split into twelve light signals by the beam splitter 64. For example, LA1 to LA12 are emitted by light source 321A; similarly, LA13 to LA24 are emitted by light source 321B. In this embodiment, the beam splitter 64 can be a lens group, such as a diffractive optical element (DOE) or an optical waveguide element, or it can be an optical fiber, such as an optical fiber splitter. As mentioned above, the probe lights LA1 to LA96 are actually emitted "simultaneously".

[0084] In this embodiment, the transmitting module 30A can cover a vertical field of view of +12.5° to -12.5°, with a vertical angular resolution of 0.26°. That is, the probe light LA1 corresponds to a vertical field of view of -12.5° to -12.24°, the probe light LA2 corresponds to a vertical field of view of -12.24° to -11.98°, and so on. Accordingly, as... Figure 6A , Figure 6BAs shown, this embodiment can calculate the vertical field of view (6.48° to 6.74°) corresponding to the probe light LA74 (rotated clockwise around the 0° reference optical axis L). According to the previous text, the field of view range greater than or equal to 6.5° (rotated clockwise around the 0° reference optical axis L) is only handled by the proximity light source. Since the probe light LA74 is a beam emitted by the light source 331B on the second light source array module 33 and generated after beam splitting, the light source 331B should be the proximity light source. Similarly, the light source 331A on the second light source array module 33 should also be the proximity light source (because the light source 331A is responsible for a larger field of view). In short, light sources 331A and 331B on the second light source array module 33 are proximity light sources, while the vertical field of view of 6.48° to 12.5° (rotated clockwise around the 0° reference optical axis L) is defined as the aforementioned first field of view 91, which is only handled by the proximity light source. The first field of view 91 corresponds to the detection range of the probe light LA74 to LA96. On the other hand, light sources 321A, 321B, 321C, and 321D on the first light source array module 32, or the other two light sources 331C and 331D on the second light source array module 33, can be distance light sources or a combination of distance and proximity light sources. They are responsible for the second field of view 92, corresponding to the vertical field of view of -12.5° to 6.48° in this embodiment, which is equivalent to... Figure 3 The second field of view, 92, was drawn.

[0085] Those skilled in the art will understand that the detection light emitted by the transmitting module 30 of the second embodiment of the present invention can be used in conjunction with other optical elements of the first embodiment to perform detection scanning of the horizontal and vertical fields of view, which will not be elaborated here.

[0086] In summary, the light sources of the transmitting module 30 in the second embodiment of the present invention can be arranged as follows: the first light source array module 32 and the second light source array module 33 each have M1 light sources and M2 light sources. The M1 light sources emit M1 light signals, and the M2 light sources emit M2 light signals. The M1 light signals are split into S1 light signals after passing through the beam splitting component 64, and the M2 light signals are split into S2 light signals after passing through the beam splitting component 64, wherein S1 is greater than M1, and S2 is greater than M2. Figure 6A M1 = M2 = 4, S1 = S2 = 12. The S1 and S2 beam splitting signals, in a direction perpendicular or not parallel to the road surface, are sequentially designated as detector light number 1, detector light number 2, detector light number 3 to detector light number x. Detector light number 1 is furthest from the top of the vehicle, and detector light number x is closest to the top of the vehicle. The field of view of detector light number n covers an angle of 6.5°. Figure 6A , Figure 6BSince x = 96 and n = 74, light sources 331A and 331B are proximity light sources, emitting probe beams 74 to 96. Light sources 321A, 321B, 321C, 321D and 331C, 331D can be distance light sources or combinations of distance and proximity light sources, emitting probe beams 1 to 73. In another embodiment, n = x, therefore there is only one light source (e.g., ...). Figure 6A The light source 331A in the image is a proximity light source.

[0087] In another embodiment, the vehicle manufacturer requires that the optical rangefinder installed on the vehicle be able to detect low-lying objects (such as crouching pedestrians, pets, etc.) within ten meters. To meet this requirement, this embodiment assumes that the optical rangefinder 1 of the present invention illuminates the road surface 4 eight meters in front of the vehicle 3 from the top of the vehicle 3. When the height H of the vehicle 3 is 1.58 meters, according to the definition of the sine of the trigonometric function, the detection angle of the optical rangefinder 1 towards the road surface 4 can be calculated to be greater than or equal to 11.4°. That is to say, in this embodiment, the field of view (the angle rotated clockwise around the 0° reference optical axis L) greater than or equal to 11.4° is only handled by the proximity light source, which can solve the aforementioned ghosting problem and simultaneously meet the requirement of detecting low-lying objects at close range.

[0088] Preferably, the center wavelength of the light signal emitted by the aforementioned proximity light source or distance light source can be 905nm, 940nm, or 1550nm; the half-width at half maximum (FWHM) of the light signal can be 0.1 to 10nm; the wavelength of the light signal has a temperature variation coefficient of less than 0.1nm / ℃, for example, 0.07nm / ℃, 0.045nm / ℃, etc.; and the light spot of the light signal is approximately circular.

[0089] Preferably, the second field of view 92 is provided by a distance measuring light source and / or a proximity measuring light source. Preferably, in embodiments of the present invention, the maximum positive angle of the vertical field of view in the direction of clockwise rotation about the 0° reference optical axis can be 12.5°, 15°, 25°, etc.; preferably, in embodiments of the present invention, the maximum angle of the vertical field of view in the direction of counterclockwise rotation about the 0° reference optical axis can be 12.5°, 15°, 25°, etc.

[0090] Accordingly, this embodiment of the invention substantially divides the vertical field of view of a single scanning optical ranging device into a low-angle field of view and a forward detection field of view. The low-angle field of view is only handled by the proximity light source. By using the low power of the proximity light source, the problem of false echo reception can be significantly reduced. Furthermore, this embodiment of the invention complies with the requirements of autonomous driving regulations, using the proximity light source to detect a field of view of 6.5° or greater (the angle of clockwise rotation of the 0° reference optical axis L). From a hardware design point of view, an optical ranging system that complies with autonomous driving regulations is planned, while also avoiding abnormal driving behavior (such as frequent braking or dangerous emergency braking) caused by misjudged signals in autonomous vehicles.

[0091] In addition, there are publicly available technologies that use software (or operating methods) to filter out the aforementioned misreceived interference signals. For example, multiple "transmit signal-receive echo" optical ranging steps are performed continuously for the same detection channel, and the TOF results from the multiple tests are compared. If the TOF results are similar, the detection result of that detection channel is considered valid; otherwise, the detection result of that channel is discarded. However, as mentioned above, in the complex road conditions of cities, performing multiple detections and calculations cannot detect objects ahead in real time, which can also burden the vehicle control system.

[0092] On the other hand, some publicly available technologies offer solutions to the blind spots of ranging devices. In other words, these solutions reinforce areas outside the field of view of the ranging device. In contrast, the embodiments of this invention plan the light source characteristics within the field of view of the ranging device. Therefore, the problems they address are different concepts. Even if we concede that the blind spot solutions mentioned in the publicly available technologies mostly involve adding extra detectors to detect blind spots, such solutions would also increase the computational burden on the vehicle control system. This is because different detectors have different placement positions, detection angles, and signal types. The data obtained from these different detectors must undergo coordinate / signal conversion, calibration, alignment, and other operations before they can be combined. Furthermore, the interference problem of each detector's own signal must be considered. Taking the high-reflectivity obstacle (such as a construction cone) mentioned in the embodiments of this invention as an example, if one detector determines that the cone is at distance A, while another detector misjudges its location as distance B due to signal interference, the vehicle control system must allocate resources to determining which detector is correct. This situation poses a potential safety hazard.

[0093] The above description is merely for explaining preferred embodiments of the present invention and is not intended to limit the present invention in any way. Therefore, any modifications or changes made to the present invention under the same inventive spirit should still be included within the scope of protection intended by the present invention.

Claims

1. An optical ranging device, mounted on the roof of a vehicle traveling on a road surface, the optical ranging device comprising: An array-type light source has a field of view perpendicular to the road surface and includes multiple light sources, including multiple proximity light sources and multiple distance light sources; The field of view includes a first field of view and a second field of view. The first field of view is the range of angles within which the reference optical axis of the optical ranging device is rotated toward the road surface by a factor of 6.5° or greater. The first field of view is provided only by the plurality of proximity light sources of the plurality of light sources in the array light source.

2. The optical distance measuring device according to claim 1, wherein The first field of view is the range of angles within which the reference optical axis of the optical ranging device rotates toward the road surface by more than or equal to 11.4°.

3. The optical distance measuring device according to claim 1, wherein The plurality of proximity light sources and the plurality of distance light sources provide multiple single line light sources for scanning the field of view, and the plurality of multiple single line light sources are used for scanning the field of view in a direction parallel to the road surface by reflection from a rotating mirror.

4. The optical distance measuring device according to claim 1, wherein The plurality of proximity light sources and the plurality of distance light sources are arranged in an aligned or staggered linear array.

5. The optical distance measuring device according to claim 1, wherein The wavelengths of the plurality of proximity light sources and / or the plurality of distance light sources are 905nm, 940nm, or 1550nm.

6. The optical distance measuring device according to claim 1, wherein The plurality of light sources are sequentially named light source 1, light source 2, light source 3 to light source x in a direction perpendicular to or not parallel to the road surface. The light source 1 is the farthest from the top of the vehicle, and the light source x is the closest to the top of the vehicle. The field of view of the nth light source covers an angle of 6.5°, where x is a positive integer greater than 1 and n is a positive integer greater than 1 and less than or equal to x. The nth to xth light sources are proximity light sources.

7. The optical distance measuring device according to claim 6, wherein Among the multiple light sources, light source 1 to light source n-1 are distance measuring light sources, or a combination of distance measuring light sources and proximity measuring light sources.

8. The optical distance measuring device according to claim 1, wherein The array-type light source includes a separate first light source array module and a second light source array module.

9. The optical ranging device according to claim 8, wherein, The first light source array module and the second light source array module each have M1 light sources and M2 light sources. The multiple M1 light sources emit M1 light signals, and the multiple M2 light sources emit M2 light signals. The multiple M1 light signals are split into S1 light signals after passing through a beam splitter, and the multiple M2 light signals are split into S2 light signals after passing through a beam splitter, wherein S1 is greater than M1, and S2 is greater than M2. The S1 light signals and the S2 light signals are perpendicular or not parallel to the path. The detectors are arranged in order along the direction of the surface: detector light number 1, detector light number 2, detector light number 3 to detector light number x. Detector light number 1 is the farthest from the top of the vehicle, and detector light number x is the closest to the top of the vehicle. The field of view of detector light number n covers an angle of 6.5°, where x is a positive integer greater than 1 and n is a positive integer greater than 1 and less than or equal to x. The light sources emitting detector light number n to detector light number x from the plurality of M1 light sources and the plurality of M2 light sources are proximity light sources.

10. The optical ranging device according to claim 9, wherein, The M1 light sources and the light sources in the M2 light sources that emit the 1st probe light to the n-1st probe light are far measurement light sources, or a combination of far measurement light sources and near measurement light sources.

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