Modern vehicles are often equipped with sensors designed to detect objects and landscape features around the vehicle in real-time to enable technologies such as lane change assistance, collision avoidance, and autonomous driving. A commonly used sensor is a light detection and ranging (LiDAR) system.
A LiDAR system may include a light source, also referred to as a transmission module (TX module), and a light detection system, also referred to as a detection module (also referred to as a receiver (RX) module), to estimate distances to environmental features (e.g., pedestrians, vehicles, structures, plants, etc.). The emitted laser beam from the TX module is used to illuminate a target and the RX module receives the reflections from the laser beam in order for the LiDAR system to measure the time it takes for the transmitted laser beam to arrive at the target and then return to the detection module. In some LiDAR systems, the laser beam may be steered across a region of interest according to a scanning pattern to generate a “point cloud” that includes a collection of data points corresponding to target points in the region of interest. The data points in the point cloud may be dynamically and continuously updated, and may be used to estimate, for example, a distance, dimension, and location of an object relative to the LiDAR system, often with very high fidelity (e.g., within about 5 cm) due to the precision of the optical alignment of the components.
In some embodiments, the present technology relates to a method of optically aligning a detection module with an optical lens assembly in a LiDAR system with the optical lens assembly coupled to a chassis. The method may comprise movably coupling a thermal management block to the chassis with a first screw coupled to the chassis. With the thermal management bloc coupled to chassis, the thermal management block the detection module may be oriented relative to the optical lens assembly to an optically aligned orientation wherein a path of a laser beam emitted from a laser module is oriented with an optical path in the optical lens assembly to a detection sensor of the detection module. With the detection module oriented, the thermal management block may be translated to be adjacent to the oriented detection module and the first screw may be tightened in order to fixedly couple the thermal management block to the chassis. With the thermal management block fixedly coupled to the chassis, a first portion of adhesive may be applied and cured between the thermal management block and the detection module, and a first portion of thermal gel may be applied between the thermal management block and the detection module.
In some embodiments, the thermal management block may include a body defining a first elongated slot and a second elongated slot, wherein movably coupling the thermal management block to the chassis with the first screw comprises positioning the first screw within the first elongated slot. In some embodiments, the method may include movably coupling the thermal management block to the chassis with a second screw positioned in the second elongated slot and coupled to the chassis, and tightening the second screw and the first screw to fixedly couple the thermal management block to the chassis.
In some embodiments, the detection module incudes a detection circuit board assembly, comprising a board and the detection sensor, and a thermal management bracket. The thermal management bracket may include a metal body. The detection circuit board assembly may be fixedly coupled to the thermal management bracket with screws.
In some embodiments, applying the first portion of adhesive between the thermal management block and detection module may include applying the first portion of adhesive between the thermal management block and the thermal management bracket. In some embodiments, curing the first portion of adhesive fixedly couples the thermal management bracket to the thermal management block.
In some embodiments, the thermal management bracket metal body may include a planar portion defining two notches. The thermal management block may include two tabs extending away from the body. Translating the thermal management block adjacent to the detection module may include positioning the two tabs within the two notches. Applying the first portion of adhesive between the thermal management block and the detection module may include applying the first portion of adhesive between a first notch, of the two notches, and a first tab, of the two tabs.
In some embodiments, the thermal management bracket may include a plurality of mounting posts extending away from the planar portion of the metal body, and the board may be fixedly coupled to the plurality of mounting posts with screws. The board may define a plurality of mountings holes each with a copper trace surrounding the respective mounting hole. The board may be fixedly coupled to the plurality of mounting posts with the screws extending through the mounting holes of the board and the copper traces contacting mounting surfaces of the mounting posts. The thermal management block may include one or more shelves, wherein each of the one or more shelves includes a horizontal surface and a vertical surface. Applying the first portion of thermal gel may include applying the first portion of thermal gel onto the planar portion of the thermal management bracket and the horizontal and vertical surfaces of the one or more shelves in order to form a thermal bridge between the detection module and the thermal management block. In some embodiments, the one or more shelves may include a first shelf, a second shelf and a third shelf. The first shelf may be on a first side of the two elongated slots, the second shelf may be on a second side of the two elongated slots, opposite the first side, and the third shelf may be between the two elongated slots.
In some embodiments, the thermal management block may include a first wing extending from a first side of the body of the thermal management block and a second wing extending from a second side of the body of the thermal management block, in order to define a length of the thermal management block. The length of the thermal management block may correspond to a length of the thermal management bracket so that that thermal energy is transferred from the thermal management bracket to the thermal management block across the respective lengths.
In some embodiments, the present technology relates to a receiver module system of a LiDAR system. The receiver module system may include a chassis, an optical lens assembly coupled to a chassis, a thermal management block coupled to the chassis with a first screw, a detection module optically aligned relative to the optical lens assembly wherein a path of a laser beam emitted from a laser module is oriented with an optical path in the optical lens assembly to a detection sensor of the detection module, adhesive directly fixedly coupling the detection module to the thermal management block in order to be fixedly couple the detection module relative to the chassis, and thermal gel forming a thermal bridge between the detection module and the thermal management block.
In some embodiments, the thermal management block includes a body defining a first elongated slot and a second elongated slot. The first screw may extend through the first elongated slot into the chassis. The thermal management block may be further coupled to the chassis with a second screw extending through the second elongated slot into the chassis. The detection module may include a detection circuit board assembly including a board and the detection sensor, and a thermal management bracket. The thermal management bracket may include a metal body. The detection circuit board assembly may be fixedly coupled to the thermal management bracket with screws. The adhesive may couple the thermal management block to the thermal management bracket. The thermal management bracket metal body may include a planar portion defining two notches. The thermal management block may include two tabs extending away from the body. The two tabs may be positioned within the two notches without contacting the planar portion. The adhesive may be positioned between the two notches and the two tabs.
In some embodiments, the thermal management bracket includes a plurality of mounting posts extending away from the planar portion of the metal body. The board may be fixedly coupled to the plurality of mounting posts with screws. The board may define a plurality of mountings holes each with a copper trace surrounding the respective mounting hole, and the board may be fixedly coupled to the plurality of mounting posts with the screws extending through the mounting holes of the board and the copper traces contacting mounting surfaces of the mounting posts. The thermal management block may include one or more shelves, wherein each of the one or more shelves comprises a horizontal surface and a vertical surface. The thermal gel may be retained between the planar portion of the thermal management bracket and the horizontal and vertical surfaces of the one or more shelves in order to form a thermal bridge between the detection module and the thermal management block. The one or more shelves may include a first shelf, a second shelf and a third shelf. The first shelf may be on a first side of the two elongated slots, the second shelf may be on a second side of the two elongated slots, opposite the first side, and the third shelf may be between the two elongated slots.
In some embodiments, the thermal management block may include a first wing extending from a first side of the body of the thermal management block and a second wing extending from a second side of the body of the thermal management block, in order to define a length of the thermal management block. The thermal management block may correspond to a length of the thermal management bracket and be configured so that that thermal energy is transferred from the thermal management bracket to the thermal management block across the respective lengths.
The features of the various embodiments described above, as well as other features and advantages of certain embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:
Throughout the drawings, it should be noted that like reference numbers are typically used to depict the same or similar elements, features, and structures.
Aspects of the present disclosure relate generally to thermal management, optical alignment, and securing of a detection module to a chassis. The detection module is optically aligned relative to an optical lens assembly, which may be shared with a transmission module, and secured to a chassis with a thermal management block. The chassis, detection module, transmission module, and optical lens assembly may be part of a LiDAR assembly, according to certain embodiments.
In the following description, various examples of thermal management and securing techniques for a detection module are described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that certain embodiments may be practiced or implemented without every detail disclosed. Furthermore, well-known features may be omitted or simplified in order to prevent any obfuscation of the novel features described herein.
The following high-level summary is intended to provide a basic understanding of some of the novel innovations depicted in the figures and presented in the corresponding descriptions provided below.
Generally, aspects of the invention are directed to implementations of fixedly coupling a detection module to a chassis so that the detection module is optically aligned with an optical lens assembly, also coupled to the chassis, and so that thermal energy (i.e. heat) generated by circuitry elements of the detection module flows to the chassis in order to dissipate the heat. For example, a Light Detection and Ranging (LiDAR) assembly of an autonomous vehicle may include a receiving module (RX) including a detection module, or a combination transmission and receiving module (TX/RX), including a detection module. The detection module comprises a detection circuit board assembly coupled to a thermal management bracket, for example a shown in
Specifically, the present technology relates to the use of a thermal management bracket, as shown in
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The board 202 comprises a plurality of mounting holes 205. For example, the board 202 of
One or more of the circuitry components of the detection circuit board assembly may generate thermal energy while in use. For example the detection sensors 203, such as APDs, generate heat due to a high reverse bias voltage. When heat is not dissipated away from the detection circuit board assembly, the excess heat may adversely affect the performance of the detection sensor 203. For example, the increased temperature may increase the thermal noise level of the detection sensor 203. Additionally or alternatively, quantum efficiency of the detection sensor 203 may also be reduced due to increased temperatures. Further, non-uniform heat distribution, with larger temperature differences, across different optical components in the system, may cause alignment issues due to non-uniform thermal expansion. Accordingly, aspects of embodiments of the present technology achieve thermal management of heat generated by the detection circuit board assembly 201 by dissipating the heat to the chassis in order to maintain the performance of the detection sensor 203.
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In embodiments, the thermal management bracket 300 is coupled to the thermal management block 400 with adhesive, and the thermal management block 400 may include features for increasing the adhesive bond strength. For example, as shown in
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The thermal management block 400 may comprise one or more elongated slots 403, for example two elongated slots 403 as shown in
The thermal management block 400 further comprises one or more shelves 404. The shelves may be shaped as an upwardly facing horizontal surface, and a vertical surface for facing the detection module 200. The shelves 404 are uses to receive thermal gel and/or adhesive. In embodiments, thermal gel may be a non-setting viscous fluid, and the shelves 404 maintain the thermal gel forming a thermal bridge between the thermal management block 400 and the thermal management bracket 300. As shown in
The thermal management block 400 may further comprise tabs 405. As shown in
The thermal management bracket 400 may be solid and formed monolithically, for example molded and/or machined from a single piece of material. In embodiments, the thermal management block 400 is comprised of a metal with a higher thermal conductivity, for example aluminum, copper and/or steel. Solid monolithically formed metal thermal management blocks are advantageous in conducting heat compared to hollow, webbed, multi-component and/or non-metal constructions.
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To optically align the detection module 200 relative to the optical lens assembly 102, the detection module 200 may be manipulated about one or more of the six degrees of freedom, eg. xyz translation and xyz rotation, and an output beam emitted from the optical lens assembly 102 may be received by the detection sensor 203 to determine that the detection module 200, and therefore detection sensor 203, is in an optically aligned orientation.
With the detection module optically aligned and held in place with an alignment jib, as shown in
The thermal management block 400 may be positions so that the shelves 404 contact, or almost contact, the surface 305 of the thermal management bracket, as shown in
With the thermal management block 400 fixedly coupled to the chassis 101, and the detection module 200 held in place and optically aligned with the optical lens assembly 102, adhesive may be applied to fixedly couple the thermal management bracket 300 to the thermal management block 400. For example, as shown in
In embodiments, the adhesive may have a low thermal conductivity and/or the thermal management bracket 300 may not contact the thermal management block 400 resulting in poor conduction of thermal energy from the detection circuit board assembly 201 to the chassis 101. Accordingly, in embodiments, a thermal gel 511 is applied between the thermal management bracket 300 and the thermal management block 400. For example, as shown in
Other variations are within the spirit of the present disclosure. Thus, while the disclosed techniques are susceptible to various modifications and alternative constructions, certain illustrated examples thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the disclosure, as defined in the appended claims. For instance, any of the examples, alternative examples, etc., and the concepts thereof may be applied to any other examples described and/or within the spirit and scope of the disclosure.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the disclosed examples (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. The phrase “based on” should be understood to be open-ended, and not limiting in any way, and is intended to be interpreted or otherwise read as “based at least in part on,” where appropriate. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate examples of the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.