In order to navigate autonomously along a roadway, an autonomous vehicle can rely on flash lidar systems to provide information regarding the surroundings of the autonomous vehicle. Flash lidar systems include a laser to illuminate a scene, where light emitted by the laser reflects from objects and is detected by a detector, and further where locations of objects in the scene (relative to the autonomous vehicle) are determined based upon the reflected light. It is desirable for a flash lidar system to have a relatively large field of view (FOV) so that observations about a relatively large scene can be generated based upon output of the flash lidar system. Lasers, however, have an inherently narrow angular spread of their emitted light, and thus for a laser to illuminate a relatively large scene, light emitted by the laser must be diffused. Accordingly, conventional flash lidar systems include a diffuser that is positioned relative to the laser to diffuse light emitted by the laser, and therefore expand a size of a scene that is illuminated by the light (and thus expand the FOV of the flash lidar system). Typically, the diffuser is directly bonded to the laser substrate of the lidar system. Directly bonding the diffuser to the laser substrate, however, can be problematic, as doing so limits directionality of the FOV of the flash lidar system. Moreover, the bonding process can be unreliable and make it difficult to qualify use in autonomous vehicles.
The following is a brief summary of subject matter that is described in greater detail herein. This summary is not intended to be limiting as to scope of the claims.
Described herein are various technologies pertaining to shaping laser illumination from a laser source in a lidar system to form a desired illumination profile. With more specificity, the lidar system has a field of view (FOV), and an aspheric lens is placed adjacent the laser source to redirect the laser illumination to one or more parts of the FOV of the lidar system. The aspheric lens is shaped to direct the laser illumination to form an illumination profile that is asymmetric across a single axis. The aspheric lens can be part of a component that is attached to a portion of the lidar system. The component can further include an attachment structure configured for securing the component to a printed circuit board (PCB) of the lidar system. In addition to securing the component to the PCB, the attachment structure is configured to position a central axis of the aspheric lens at a desired position relative to a central axis of the laser source in the lidar system. The component can further include a feedback structure that can be employed to indicate to a user that the component is properly attached to the lidar system.
The component can additionally include a second aspheric lens that aligns with a second laser source in the lidar system to create a second illumination profile, where the second illumination profile can be similar to the asymmetric illumination profile or can be different from the asymmetric illumination profile. The attachment structure can be configured to position a central axis of the second aspheric lens at a desired position relative to a central axis of the second laser source in the lidar system.
In one embodiment, the component can be manufactured as a singular unit via plastic injection molding. Different mold inserts can be placed into a mold cavity to form the different parts. For instance, a first mold insert can be shaped to form a surface profile of the aspherical lens while a second mold insert can be shaped to form the feedback structure during the injection molding process. By manufacturing the component as singular unit, the same material can be used to form each part of the component saving system assembly costs and time and providing a more reliably repeatable assembly process.
The above-described technologies present various advantages over conventional laser illumination diffusers used in a lidar system for an autonomous vehicle. Conventionally, near-field lidar systems are positioned near a roofline of the autonomous vehicle and are pointed down towards the ground in order to detect objects that are in close proximity to the autonomous vehicle. When laser illumination emitted by a laser sensor is diffused using conventional diffusing technologies in near-field lidar systems, a relatively high concentration of light is directed towards the ground within 3-6 feet of the autonomous vehicle, while a relatively low concentration of light is directed towards the ground between 6 and 15 feet from the autonomous vehicle.
Conventional diffusers are not configured to diffuse light from a laser source and produce an illumination profile that is asymmetric across a single axis. This discrepancy uses up dynamic range of the lidar sensor system, is wasteful of power output by the lidar system, and causes an unnecessary amount of heat output from the lidar system.
The above summary presents a simplified summary in order to provide a basic understanding of some aspects of the systems and/or methods discussed herein. This summary is not an extensive overview of the systems and/or methods discussed herein. It is not intended to identify key/critical elements or to delineate the scope of such systems and/or methods. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.
Various technologies pertaining to shaping laser illumination from a laser source in a lidar system to form a particular illumination profile are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more aspects. Further, it is to be understood that functionality that is described as being carried out by certain system components may be performed by multiple components. Similarly, for instance, a component may be configured to perform functionality that is described as being carried out by multiple components.
In reference to the disclosure herein, for purposes of convenience and clarity only, directional terms, such as, top, bottom, left, right, up, down, upper, lower, over, above, below, beneath, rear, and front, may be used. Such directional terms should not be construed to limit the scope of the features described herein in any manner. It is to be understood that embodiments presented herein are by way of example and not by way of limitation. The intent of the following detailed description, although discussing exemplary embodiments, is to be construed to cover all modifications, alternatives, and equivalents of the embodiments as may fall within the spirit and scope of the features described herein.
Moreover, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from the context, the phrase “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, the phrase “X employs A or B” is satisfied by any of the following instances: X employs A; X employs B; or X employs both A and B. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from the context to be directed to a singular form.
Further, as used herein, the term “exemplary” is intended to mean serving as an illustration or example of something and is not intended to indicate a preference.
Disclosed are various technologies that generally relate to shaping laser illumination from a laser source in a lidar system to form a particular illumination profile proximate an autonomous vehicle. A component with an aspherical lens is attached to the lidar system, where the aspherical lens is shaped to steer a portion of the laser illumination to a part of the field of view of the lidar system. The component can have an attachment structure that permits removable attachment to the lidar system and a feedback structure that creates a feedback loop to indicate when the component is attached to the lidar system and the lens is properly aligned with a corresponding laser source.
With reference now to
In the illustrated embodiment, the component 100 comprises a rectangular component body 102 that includes lenses 104 for redirecting laser illumination from the laser source(s) and an attachment structure 106 for securing the component body 102 to a portion of the lidar system. The component 100 can further include a feedback structure 108 configured to indicate when the component body 102 is properly attached to the lidar system and properly aligned relative to the laser source(s), as will be described in detail below.
The lenses 104 in the component body 102 are used to redirect laser illumination from the laser sources for a variety of purposes. First, diffusing the laser illumination increases the eye safety of the lidar system. For instance, light emitted from a laser source, without being diffused, that impacts an eye of a human may damage the eye due to the intensity of the light. Spreading the laser illumination via the lens 104 decreases the maximum intensity of laser light that could impact the eye, and increases eye safety of the laser illumination.
In addition to increasing eye safety, diffusing the laser illumination increases the field of view (FOV) to a desired level for the lidar system. However, as mentioned above, when common diffusing technologies are used for a near-field lidar system positioned near a roofline of the autonomous vehicle, an excessive amount of laser illumination is projected to the bottom of the FOV comprising the ground within 0-6 feet of the autonomous vehicle as compared to the top of the FOV comprising the ground within 6-20 feet of the autonomous vehicle. More particularly, lidar systems project laser illumination out into the world with an intensity defined by an illumination profile. In order to detect an object within any part of the FOV, the amount of returned laser light from the object needs to be greater than a minimum threshold for the lidar system. The quantity of returned laser light from an object is calculated using a lidar equation.
A dominant term in the lidar equation is the distance (or range) between the lidar system and the object. As an object gets further away, the amount of laser intensity returned to the lidar system decreases as a square function; returned laser light is proportional to 1/(range{circumflex over ( )}2). Therefore, in order to detect an object, the quantity of projected laser illumination needs to be much greater for objects that are further away. If the lidar system is used in a scenario with boundaries on the possible object distances within different areas of the FOV, an improvement in performance can be gained by setting an appropriate illumination pattern.
A conventional diffusing technology has a symmetric profile of illumination across the center of the FOV (the optical axis). If this illumination profile were projected onto a flat surface at a perpendicular angle, then the conventional diffusing pattern would be roughly appropriate.
However, near-field lidar systems on autonomous vehicle project laser illumination at an angle relative to a flat road surface. As a result, when conventional diffusing technologies are used for the near-field lidar system, an equal amount of light is distributed to the bottom of the FOV, within 0-6 feet from the autonomous vehicle, and the top of the FOV, within 6-20 feet from the autonomous vehicle. This can be seen in
Conversely,
Accordingly, the lenses 104 in the component body 102 are designed to adjust the proportion of laser illumination that is directed to different parts of the FOV. In the illustrated embodiments, the particular illumination profile is asymmetric across a single axis. However, the lenses 104 described herein can be designed to direct laser illumination to any desired parts of the FOV.
The component body 102 includes any suitable number of lenses 104 and the number may depend on the lidar system, the illumination profile(s), and/or the like. For instance, the number of lenses 104 may depend on the number of laser sources covered by the component body 102. The component body 102 may have a separate lens for each laser source and/or a lens may be shared between multiple laser sources. The lenses 104 can have any suitable shape and/or size cross-section, such as circular, ovular, rectangular, triangular, or the like, for forming the illumination profile(s). In the illustrated embodiment, the component body 102 includes two lenses that are arranged coaxially on opposite sides of the feedback structure 108.
Any suitable method can be used to determine a profile of one or more surfaces of the lenses 104 that results in the asymmetric illumination profile. For instance, ray tracing software can be used to simulate a model of the laser illumination from the laser sources and an effect of the lenses 104. The surface(s) of the lenses 104 can then be optimized using a customized function within the ray tracing software that is matched to the desired illumination profile of the lidar system (e.g., the asymmetric illumination profile).
Illustrated in
A second surface 204 of the lens 200 that is opposite the first surface 202 has a calculated profile that results in a particular angle of refraction as the laser illumination exits the lens 200. Similar to the first surface 202, using Snell's Law, the angle of refraction of laser illumination at the second surface 204 can be determined based on the angle of incidence at which the laser illumination traveling through the lens 200 impacts the second surface 204. Because the angle of incidence for the laser illumination at the second surface 204 is the angle of refraction at the first surface 202, the profile of the first surface 202 and the profile of the second surface 204 are intertwined. As can be seen in
The profile of the first surface 202 and/or the profile of the second surface 204 can be rotationally symmetric about a central axis X of the lens 200, as illustrated, and/or different portions with respect to the central axis X may have different profiles.
As can be seen in
As can be seen further in
The surface profiles of each lens 104 in the component body 102 can be similar and/or can vary. For instance, a first circular lens can have a first surface profile and a second circular lens can have a second surface profile that is different from the first surface profile. The different surface profiles may be based on different laser sources, different illumination profiles, and/or the like.
As briefly mentioned above, the component body 102 includes attachment structure 106 for securing the component body 102 to the lidar system. In the embodiment illustrated in
As briefly mentioned above, the component 100 can further include the feedback structure 108 that can inform a user when the component body 102 is properly attached to the lidar system. For instance, the feedback structure 108 can be shaped to form a feedback loop with the lidar system when the component body 102 is properly attached to the lidar system, where the feedback loop otherwise would not exist. Thus, a computing system and/or user can monitor whether the feedback loop is present to determine whether the component body 102 is properly attached to the lidar system. Where the feedback loop is not present, laser illumination from laser sources associated with that feedback loop may be halted. For instance, a computing system may stop the laser source from emitting laser illumination if the component 100 becomes detached and/or misaligned because the laser illumination may be no longer eye safe.
The feedback structure 108 can take any suitable shape for forming this feedback loop. In the embodiment illustrated in
A first side of the prism structure 110 illustrated in
Turning now to
Any suitable method can be used to manufacture the component 100. In one embodiment, the different components are manufactured individually and then combined together to form the component 100. In another embodiment, the component 100 is manufactured via plastic injection molding as a singular unit. In this embodiment, different shaped mold inserts can be placed in the mold to form the different portions of the component 100. For instance, a mold insert can be shaped to form the surface profile for one of the lenses in the component 100. In another example, a mold insert can be shaped to form a portion of a prism structure of a feedback structure.
The component 100 can be formed of any suitable material and different portions of the component 100 may be formed of similar material and/or can vary. For instance, where the component 100 comprises a singular unit formed by plastic injection molding, the component 100 can be formed of ZEONEX E48R Cyclo Olefin Polymer. In another example, the lens 104 of the component 100 can be formed of a first material while the feedback structure 108 can be formed of a different second material.
Referring solely to
In an embodiment of the methodology 500, the step of forming the aspheric lens comprises placing a mold insert into a plastic injection mold cavity. The mold insert can be shaped to form the aspheric lens during the injection molding process.
In another embodiment of the methodology 500, the step of forming the attachment structure comprises forming a hole that extends through the component body.
In a further embodiment of the methodology 500, the step of forming the component body further comprises forming a second aspheric lens. The second aspheric lens can be shaped to direct laser illumination from a second laser source in the lidar system to produce a second asymmetric illumination profile. The attachment structure can be further configured to space a central axis of the second aspheric lens a second distance from a central axis of the second laser source in the lidar system.
In yet another embodiment of the methodology 500, the step of forming the component body further comprises forming feedback structure configured for generation of a feedback loop with the printed circuit board of the lidar system. The feedback loop can indicate to a computing system that the component body is secured to the printed circuit board of the lidar system.
In a version of this embodiment, the step of forming the feedback structure comprises forming a prism structure that reflects light emitted from a light emitting diode on the printed circuit board back toward a photodiode on the printed circuit board.
The methodology 600 starts at 602, and at 604 a feedback loop is created via a component to indicate that the component is properly attached to a PCB of a lidar system of an autonomous vehicle and aligned with a laser source on the PCB. The feedback loop can be created by reflecting a light from an LED on the PCB back toward a photodiode on the PCB. At 606, laser illumination is emitted from a laser source on the PCB in the lidar system. At 608, the laser illumination is refracted at a first angle as the laser illumination enters an aspheric lens in the component. At 610, the laser illumination is refracted at a second angle as the laser illumination exits the aspheric lens in the component to form a desired illumination profile. At 612, a detector of the lidar system captures laser illumination reflected off an object exterior of autonomous vehicle that is in the desired illumination profile. The methodology 600 concludes at 614.
Referring now to
What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable modification and alteration of the above devices or methodologies for purposes of describing the aforementioned aspects, but one of ordinary skill in the art can recognize that many further modifications and permutations of various aspects are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the details description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.