LIDAR occlusion detection method and system

Abstract

The present disclosure relates to systems and methods for occlusion detection. An example method includes scanning, with a light detection and ranging (LIDAR) device, at least a portion of an external structure within a field of view (FOV) of the LIDAR device. The LIDAR device is physically coupled to the external structure. The scanning includes transmitting a light pulse to the external structure through an optical window and receiving a reflected light pulse through the optical window. The reflected light pulse includes a reflection of the transmitted light pulse from the external structure back to the LIDAR device. The method also includes detecting the presence of an occlusion that at least partially obscures the scanning FOV of the LIDAR device based at least on the scanning of at least a portion of the external structure.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 17 / 131,594 filed on December 22, 2020 and U.S. provisional patent application No. 62 / 954,338 filed on December 27, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to light detection and ranging (lidar) systems, and more particularly to systems and methods for occlusion detection. Background Art

[0004] Some light detection and ranging (lidar) systems utilize a light emitting transmitter (e.g., a laser diode) to emit light pulses into the environment. The emitted light pulses, which interact with (e.g., are reflected from) objects in the environment, can then be received by a receiver (e.g., a photodetector) of the lidar system. Range information about objects in the environment can then be determined based on the time difference between the emission time of the light pulse and the reception time of the return reflection of the emitted light pulse. Summary of the Invention

[0005] In one example, a method is provided. The method includes scanning, by a light detection and ranging (LIDAR) device physically coupled to an external structure, at least a portion of the external structure within a field of view (FOV) of the LIDAR device. The scanning includes sending light pulses through an optical window toward the external structure in different directions. The scanning also includes receiving reflected light pulses through the optical window, the reflected light pulses including reflections of the sent light pulses returning from the external structure to the LIDAR device. The method also involves detecting the presence of an obstruction that at least partially obscures the LIDAR device's scanning FOV based at least on the scanning of the at least a portion of the external structure.

[0006] In another example, a system is provided. The system includes a mounting structure, a light detection and ranging (LIDAR) device mounted to the mounting structure, an optical window, one or more processors, and a data storage device. The data storage device stores instructions that, when executed by the one or more processors, cause the system to perform operations. The operations include scanning at least a portion of the mounting structure within a field of view (FOV) of the LIDAR device. Scanning involves sending light pulses from the LIDAR device toward the mounting structure through the optical window in different directions. Scanning also involves receiving reflected light pulses through the optical window, the reflected light pulses including reflections of the sent light pulses returning from the mounting structure to the LIDAR device. The operations also include detecting the presence of an obstruction that at least partially obscures the LIDAR device's scanning FOV based at least on the scanning of the at least a portion of the mounting structure.

[0007] In yet another example, a non-transitory computer-readable medium is provided. The non-transitory computer-readable medium stores instructions that, when executed by one or more processors, cause a system to perform operations. The operations include scanning at least a portion of the external structure within a field of view (FOV) of the LIDAR device using a light detection and ranging (LIDAR) device physically coupled to an external structure. The scanning includes sending light pulses in different directions toward the external structure through an optical window of the LIDAR device. The scanning also includes receiving reflected light pulses through the optical window, the reflected light pulses including reflections of the sent light pulses returning from the external structure to the LIDAR device. The operations also include detecting the presence of an obstruction that at least partially obscures the LIDAR device's scanning FOV based at least on the scanning of the at least portion of the external structure.

[0008] In yet another example, a system is provided. The system includes means for scanning, by a light detection and ranging (LIDAR) device physically coupled to an external structure, at least a portion of the external structure within a field of view (FOV) of the LIDAR device. The scanning includes transmitting light pulses through an optical window toward the external structure in different directions. The scanning also includes receiving reflected light pulses through the optical window, the reflected light pulses comprising reflections of the transmitted light pulses returning from the external structure to the LIDAR device. The system also includes means for detecting the presence of an occlusion that at least partially obscures the LIDAR device's scanning FOV based at least on the scanning of the at least a portion of the external structure.

[0009] Other aspects, embodiments, and implementations will become apparent to those of ordinary skill in the art by reading the following detailed description and, where appropriate, referring to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a simplified block diagram of a system according to an example embodiment.

[0011] Figure 2 A LIDAR device is shown mounted to a mounting structure according to an example embodiment.

[0012] Figure 3A A first view of a carrier is shown according to an example embodiment.

[0013] Figure 3B A second view of a carrier is shown according to an example embodiment.

[0014] Figure 3C A third view of a carrier is shown according to an example embodiment.

[0015] Figure 3D A fourth view of a carrier is shown according to an example embodiment.

[0016] Figure 3E A fifth view of a carrier is shown in accordance with an example embodiment.

[0017] Figure 4 A method according to an example embodiment is shown.

[0018] Figure 5 Another method according to an example embodiment is shown. DETAILED DESCRIPTION

[0019] Example methods, devices, and systems are described herein. It should be understood that the words "example" and "exemplary" as used herein mean "serving as an example, instance, or illustration." Any embodiment or feature described herein as "example" or "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or features. Other embodiments may be utilized, and other changes may be made, without departing from the scope of the subject matter presented herein. Therefore, the example embodiments described herein are not meant to be limiting. As generally described herein and illustrated in the accompanying drawings, various aspects of the disclosure may be arranged, substituted, combined, separated, and designed in a variety of different configurations, all of which are contemplated herein. In addition, unless the context suggests otherwise, the features shown in each of the figures may be used in combination with each other. Therefore, the accompanying drawings Figure 1 These should generally be viewed as forming aspects of one or more overall embodiments, with it being understood that not all illustrated features are necessary for every embodiment.

[0020] 1. Overview

[0021] An example lidar system herein includes a transmitter and a receiver. The transmitter may include one or more light emitter devices (e.g., one or more laser bars, each having one to eight laser diodes) configured to transmit light into the environment of the lidar system via one or more optical elements in a transmission path (e.g., a transmitting lens, a rotatable mirror, and an optical window). The rotatable mirror may be configured to rotate around a mirror rotation axis. The rotatable mirror may be configured to interact with light pulses reflected by the one or more light emitter devices so as to direct light pulses in different directions into the field of view (FOV) of the lidar system. Furthermore, the rotatable mirror may be configured to direct the light pulses to the receiver after the light pulses have interacted with the environment to form return light pulses.

[0022] In an example, systems and methods for occlusion detection are provided. For example, an example occlusion detection system can provide a way to determine the presence of dust, dirt, and / or cracks on an optical window and / or other types of occlusions that at least partially obstruct a LIDAR system's scanning FOV via the optical window.

[0023] Continuing with the above example, the LIDAR system can include a reflective mounting bracket disposed at least partially outside of an optical cavity including a transmitter and a receiver. In some implementations, the reflective mounting bracket can physically couple the LIDAR system to a mounting surface. The mounting surface can include, for example, a vehicle body.

[0024] In one implementation, the reflective mounting bracket can include a reflective surface configured to reflect at least a portion of the emitted light (sent from the transmitter through the optical window) back to the LIDAR system (and through the optical window) for receipt by the receiver. For example, the reflective surface can correspond to a portion of the reflective mounting bracket that is within the FOV scanned by the LIDAR system. In some embodiments, the mounting bracket (or the portion thereof that is scanned) is within a given distance (e.g., 50 mm, etc.) from the optical window.

[0025] In another implementation, the exterior surface of any other external structure physically coupled to the LIDAR device can reflect at least a portion of the emitted light instead of or in addition to being reflected at the mounting bracket. In one example, the mounting bracket can be configured to mount the LIDAR device to the body of a vehicle. In this example, the exterior surface can correspond to any exterior surface of the vehicle that is within the FOV of the LIDAR device (e.g., a body panel, side mirror structure, bumper, fender, etc.). Thus, in this example, the exterior surface can remain in a fixed position relative to the LIDAR device even as the vehicle moves through the environment. In another example, the LIDAR device can be mounted to a building. In this example, the exterior structure / exterior surface can instead include a wall, door, window frame, or any other exterior feature of the building that is within the FOV of the LIDAR device. Other examples are also possible.

[0026] In some examples, scanning of a reflective mounting bracket (or other external structure) can be used to detect the presence of an obstruction on or near the optical window. For example, if light reflected from a reflective mounting bracket (or external structure) and received by the LIDAR device has a lower-than-expected intensity, the example system can determine that the obstruction (e.g., dirt, dust, mud, water, etc.) has reduced the energy transmitted to and / or received from the reflective surface of the mounting bracket (or external structure). Thus, by scanning the reflective surface of the mounting bracket, the example system can be configured to determine whether an obstruction exists on the optical window or elsewhere along the light path between the LIDAR device and the mounting bracket (or external structure).

[0027] Additionally or alternatively, in some examples, scanning can be used to detect optical defects in the LIDAR device. For example, if light reflected from an external structure (e.g., a mounting bracket) and received by the LIDAR device has a lower-than-expected intensity, the example system can determine that an optical defect associated with a reduction in light intensity (e.g., laser dimming) is present. For example, the optical defect can involve a change in the relative position of one or more optical components in the LIDAR device (e.g., optical misalignment), aging of one or more light emitters (e.g., laser diodes) in the LIDAR device, and / or any other type of optical defect that can cause light transmitted and / or received by the LIDAR device to dim (e.g., a reduction in light intensity).

[0028] 2. Example System

[0029] Figure 1A system 100 is shown according to an example embodiment. In some embodiments, the system 100 can be a laser-based distance and ranging (lidar) system or portion thereof. In this scenario, the system 100 can be configured to emit light pulses into an environment 10 to provide information indicating an object 12 within a field of view (FOV) 17. As shown, the system 100 can include or can be physically coupled to an external structure 190. For example, the system 100 can be mounted in a given position relative to the external structure 190 such that the system 100 and the external structure 190 maintain a predetermined physical arrangement relative to each other.

[0030] In some examples, system 100 can be coupled to a vehicle (or other system) to provide information about the vehicle's external environment. In one example, external structure 190 can include a mounting structure (e.g., a mounting bracket) that physically couples system 100 to the vehicle. Thus, in this example, system 100 can remain in a given position relative to the mounting structure (e.g., even if the vehicle moves within the environment). In other examples, external structure 190 can include any structure (e.g., a side mirror structure of a vehicle, a body panel of a vehicle, a bumper of a vehicle, etc.) that is physically coupled to system 100 such that an outer surface of the external structure remains in a fixed position relative to a given position of system 100 (e.g., even if the vehicle moves within the environment).

[0031] As shown, the external structure 190 may optionally include one or more calibration targets 192. For example, the calibration target 192 may include one or more surfaces with a specific texture, a surface with varying reflectivity and / or emissivity, a patterned target, etc. For example, a specific calibration target may be configured to redirect or absorb all incident beam energy except for a given portion away from the receiver 121 (e.g., a black dot-shaped surface set on a tilt mirror, etc.). Various other example calibration target configurations are also possible. In some examples, the calibration target 192 may be set on at least a portion of the external structure 190 within the FOV 17. In this way, the system 100 can be configured to scan at least a portion of the external structure 190 (where the calibration target 192 is located) when scanning the FOV 17.

[0032] As shown, system 100 includes a rotatable base 110 configured to rotate about a first axis 102. In some embodiments, a base actuator 112 is operable to rotate the rotatable base 110 about the first axis 102 at an azimuth rotation rate between 3 Hz and 60 Hz (e.g., between 180 revolutions per minute (RPM) and 3600 RPM). However, other azimuth rotation rates are also possible and contemplated. In some embodiments, the base actuator 112 can be controlled by a controller 150 to rotate at a desired rotation rate. In this scenario, the controller 150 can control the base actuator 112 to rotate at a single target rotation speed, and / or the controller 150 can dynamically adjust the desired rotation rate of the base actuator 112 within a possible range of rotation rates.

[0033] In some embodiments, the base actuator 112 can include an electric motor. For example, the electric motor can include a stator 116 and a rotor 114 operable to rotate a shaft 118 of the rotatable base 110. In various embodiments, the base actuator 112 can be a direct current (DC) motor, a brushless motor, or another type of rotary actuator. In some embodiments, the shaft 118 can be coupled to the rotatable base 110 by means of one or more bearings 119. The bearings 119 can include rotary bearings or another type of low-friction bearing.

[0034] In some embodiments, system 100 need not include rotatable base 110. In such a scenario, one or more components of system 100 within housing 160 can be configured to rotate about first axis 102. However, in other cases, some components of system 100 need not rotate about first axis 102. Thus, in such embodiments, system 100 can be used for line scanning applications, single point scanning applications, and the like.

[0035] The system 100 also includes a mirror assembly 130 having a shaft 134 and a mirror body 133, the mirror body 133 being configured to rotate about a mirror rotation axis 131. In some embodiments, the mirror rotation axis 131 can be substantially perpendicular to the first axis 102 (e.g., within a vertical range of 0 to 10 degrees). In an example embodiment, the mirror actuator 136 can be configured to rotate the mirror body 133 about the mirror rotation axis 131 at a mirror rotation rate between 100 Hz and 1000 Hz (e.g., between 6000 RPM and 60,000 RPM). In some scenarios, the mirror body 133 can be configured to rotate about the mirror rotation axis 131 within a rotation period (e.g., between 3.3 milliseconds and 1 millisecond).

[0036] The mirror actuator 136 can be a DC motor, a brushless DC motor, an AC motor, a stepper motor, a servo motor, or another type of rotary actuator. It should be understood that the mirror actuator 136 can operate at various rotational speeds or desired rotational speeds and can be controlled by the controller 150.

[0037] In an exemplary embodiment, the mirror assembly 130 includes a plurality of reflective surfaces 132. For example, the plurality of reflective surfaces 132 may include four reflective surfaces. In various embodiments, the reflective surfaces 132 may be formed from at least one of gold, silicon oxide, titanium oxide, titanium, platinum, or aluminum. In such a scenario, the four reflective surfaces may be arranged symmetrically about the mirror rotation axis 131, such that the mirror body 133 of the mirror assembly 130 has a rectangular prism shape. It should be understood that the mirror assembly 130 may include more or fewer than four reflective surfaces. Thus, the mirror assembly 130 may be shaped like a polygonal prism with more or fewer than four sides. For example, the mirror assembly 130 may have three reflective surfaces. In such a scenario, the mirror body 133 may have a triangular cross-section.

[0038] In some embodiments, the mirror body 133 can be configured to couple the plurality of reflective surfaces 132 to the shaft 134. In such a scenario, the mirror body 133 can be substantially hollow. In various embodiments, at least a portion of the mirror body 133 can have an octagonal cross-section and / or four-fold symmetry. In one example, the mirror body 133 can comprise a polycarbonate material. In this example, the octagonal and / or four-fold symmetric configuration of the mirror body 133 can help reduce potential slippage of the polycarbonate material of the mirror body 133 on the shaft 134 during rotation of the mirror body. Other examples are also possible.

[0039] In some embodiments, the mirror body 133 may include a plurality of flexible support members 138. In such a scenario, at least one flexible support member 138 may be straight. Additionally or alternatively, at least one flexible support member 138 may be curved. In some embodiments, based on the geometry of the system of flexible support members, the mirror body 133 may be rigid in some directions (e.g., to support loads in rotation) and elastic in some directions to accommodate thermal expansion. For example, the flexible support member 138 may be configured to be substantially rigid in torsion and substantially elastic in response to forces perpendicular to the axis of rotation. In various embodiments, the mirror body 133 may be formed of an injection-molded material. Additionally, the shaft 134 may be formed of steel or another structural material.

[0040] In some embodiments, the mirror assembly 130 can include an encoder magnet 139 that can be coupled to the shaft 134. In such a scenario, the encoder magnet 139 is configured to provide information indicating the rotational position of the rotatable mirror assembly 130 relative to the transmitter 127 and the receiver 121.

[0041] In some embodiments, the encoder magnet 139 can also be configured as a mirror motor magnet (e.g., included in the mirror actuator 136). In these embodiments, the system 100 can use the magnet 139 to help measure and adjust the rotational position of the rotatable mirror assembly 130. In one example embodiment, the magnet 139 can be one of a plurality of magnets (e.g., a magnetic ring, etc.) arranged in a circular arrangement and configured to interact with a magnetic field (e.g., generated at the actuator 136) to cause rotation of the mirror assembly. Other embodiments are also possible.

[0042] In various examples, the mirror assembly 130 can additionally or alternatively include a coupling bracket 135 configured to couple at least a portion of the mirror assembly 130 to other elements of the system 100, such as the housing 160. The coupling bracket 135 can be configured to attach the mirror assembly 130 to the housing 160 by way of one or more connectors 137. In such a scenario, the coupling bracket 135 and the connectors 137 can be configured to be easily removed from the other elements of the system 100. Such easy removability can provide better recalibration, service, and / or repair options.

[0043] System 100 also includes an optical cavity 120 coupled to rotatable base 110. The optical cavity includes a transmitter 127 having at least one light emitter device 126 and a light emitter lens 128. In an exemplary embodiment, at least one light emitter device 126 may include one or more laser diodes. Other types of light sources are also possible and contemplated. At least one light emitter device 126 and light emitter lens 128 are arranged to define a light emission axis 18.

[0044] In various embodiments, rotatable mirror assembly 130 may be configured to controllably rotate about mirror rotation axis 131 to transmit transmitted light to a location within environment 10 and receive return light from a location within environment 10 .

[0045] The optical cavity 120 also includes a receiver 121 configured to detect the return light 16 from the environment 10. The receiver 121 includes a plurality of photodetectors 122. For example, the plurality of photodetectors 122 may include at least one solid-state single-photon sensitive device. For example, in some embodiments, the plurality of photodetectors 122 may include one or more silicon photomultipliers (SiPMs). In such a scenario, each SiPM may include a plurality of single-photon avalanche diodes (SPADs) (e.g., a two-dimensional array of SPADs). Additionally or alternatively, the plurality of photodetectors 122 may include avalanche photodiodes (APDs), infrared photodiodes, photoconductors, or another type of photodetector. Furthermore, it should be understood that systems incorporating a plurality of photodetectors, such as a focal plane array or another type of image sensor, are also possible and contemplated.

[0046] The plurality of photodetectors 122 includes a corresponding set of two or more photodetectors for each of the at least one light emitter device 126. In various embodiments, the at least one light emitter device 126 can be configured to emit light pulses that interact with the mirror assembly 130 such that the light pulses are redirected as transmitted light 14 to the environment 10 of the system 100. In such a scenario, at least a portion of the light pulses can be reflected back to the system 100 as return light 16 and received by the plurality of photodetectors 122 to determine at least one of a time of flight, a distance to the object 12, and / or a point cloud.

[0047] In an example embodiment, the photodetector 122 may provide an output signal to the controller 150. For example, the output signal may include information indicative of the time of flight of a given light pulse toward a given portion of the field of view 17 of the environment 10. Additionally or alternatively, the output signal may include information indicative of at least a portion of a range map or point cloud of the environment 10.

[0048] In some embodiments, each set of two or more photodetectors may include a primary light detector 123 and a secondary light detector 125. The primary light detector 123 is configured to receive a first portion of the return light 16 corresponding to a light pulse emitted from a given light emitter device. In such a scenario, the secondary light detector 125 is configured to receive a second portion of the return light emitted from the given light emitter device.

[0049] In various embodiments, the first portion of the returned light 16 and the second portion of the returned light 16 can have significantly different intensities. For example, the first portion of the returned light 16 can be at least an order of magnitude greater in photon flux than the second portion of the returned light 16.

[0050] In an exemplary embodiment, the at least one light emitter device 126 may include a four-element laser diode bar (e.g., four discrete light sources disposed on the laser bar). In such a scenario, the plurality of photodetectors 122 may include four primary light detectors. Each primary light detector may correspond to a corresponding light emitter on the laser diode bar. Furthermore, the plurality of photodetectors 122 may include four secondary light detectors. Each secondary light detector may correspond to a corresponding light emitter on the laser diode bar.

[0051] In alternative embodiments, the at least one light emitter device 126 may include two or more laser diode bars, and a laser bar may include more or fewer than four light emitter devices.

[0052] In some embodiments, the light emitter device 126 can be coupled to a laser pulser circuit operable to cause the light emitter device 126 to emit one or more laser pulses. In such a scenario, the laser pulser circuit can be coupled to a trigger source, which can include the controller 150. The light emitter device 126 can be configured to emit infrared light (e.g., light having a wavelength between 800-1600 nanometers (nm), such as 905 nm). However, other wavelengths of light are also possible and contemplated.

[0053] Receiver 121 also includes a photodetector lens 124. Multiple photodetectors 122 and photodetector lens 124 are arranged to define a light receiving axis 19. At least one of light receiving axis 19 or light transmitting axis 18 is tilted relative to first axis 102. For example, the tilt angle may be between 5 and 30 degrees. However, other tilt angles are possible and contemplated.

[0054] Receiver 121 also includes a plurality of holes 178, which may be openings in orifice plate 176. In various embodiments, orifice plate 176 may have a thickness between 50 microns and 200 microns. Additionally or alternatively, at least one hole in plurality of holes 178 may have a diameter between 150 microns and 300 microns. However, other hole sizes larger and smaller than this range are possible and contemplated. Furthermore, in an exemplary embodiment, corresponding holes in plurality of holes 178 may be spaced 200 microns and 800 microns apart. Other hole spacings are also possible and contemplated.

[0055] The receiver 121 may further include one or more optical redirectors 129. In such a scenario, each optical redirector 129 may be configured to optically couple a corresponding portion of the return light 16 from the corresponding aperture to at least one photodetector in the plurality of photodetectors 122. For example, each optical redirector may be configured to optically couple a corresponding portion of the return light from the corresponding aperture to at least one photodetector in the plurality of photodetectors by total internal reflection.

[0056] In some embodiments, the optical redirector 129 can be formed from an injection moldable optical material. In such a scenario, the optical redirector 129 is coupled together in a pair of elements, such that a first element and a second element of the pair are shaped to be slidably coupled to each other. In an example embodiment, the optical redirector 129 is configured to split the return light 16 into unequal portions, such that a first photon flux of a first portion of the return light 16 illuminates a first photodetector, and a second photon flux of a second portion of the return light 16 illuminates a second photodetector.

[0057] In some examples, the optical redirector 129 can also be configured to expand the beam width of the first portion of the return light 16 that impinges on the first photodetector (and / or the second portion of the return light 16 that impinges on the second photodetector). In this manner, for example, the detection areas at the respective photodetectors onto which the respective portions of the return light 16 impinge can be larger than the cross-sectional areas of their associated apertures.

[0058] In various example embodiments, the rotatable base 110, the mirror assembly 130, and the optical cavity 120 can be configured to provide a field of view 17. In some embodiments, the field of view 17 can include a 360-degree azimuth range about the first axis 102 and an elevation range between 60 and 120 degrees (e.g., at least 100 degrees) about the mirror rotation axis 131. In one embodiment, the elevation range can be configured to allow the system 100 to direct one or more emitted light beams along the first axis 102 (and / or in a direction substantially parallel to the first axis 102). It will be understood that other azimuth and elevation ranges are possible and contemplated.

[0059] In some embodiments, the field of view 17 can have two or more continuous angular ranges (e.g., "separate" or discontinuous fields of view). In one embodiment, the two or more continuous angular ranges can extend away from the same side of the first axis 102. Alternatively, in another embodiment, the two or more continuous angular ranges can extend away from opposite sides of the first axis 102. For example, a first side of the first axis 102 can be associated with elevation angles between 0 and 180 degrees, and a second side of the first axis can be associated with elevation angles between 180 and 360 degrees.

[0060] In some embodiments, the system 100 includes a rotatable housing 160 having an optical window 162. The optical window 162 can include a flat window. Additionally or alternatively, the optical window 162 can include a curved window and / or a window with refractive optical power. For example, a curved window can provide an extended field of view (compared to a flat optical window) at the expense of some loss or reduction in beam quality. In such a scenario, light pulses can be emitted toward the environment 10 through the optical window 162, sent through the environment 10, and received from the environment 10. Furthermore, while one optical window is described in various embodiments herein, it will be understood that examples with more than one optical window are possible and contemplated.

[0061] The optical window 162 can be substantially transparent to light having a wavelength such as the emitted light pulse (e.g., an infrared wavelength). For example, the optical window 162 can include an optically transparent material configured to transmit the emitted light pulse in the infrared wavelength range with a transmission efficiency greater than 80%. In one embodiment, the transmission efficiency of the optical window 162 can be greater than or equal to 98%. In another embodiment, the transmission efficiency of the optical window 162 can vary depending on the incident angle of the transmitted light and / or received light incident on the optical window 162. For example, when light is incident on the optical window from a relatively higher incident angle, the transmission efficiency may be lower than when the light is incident from a relatively lower incident angle.

[0062] In some examples, optical window 162 can be formed from a polymeric material (eg, polycarbonate, acrylic, etc.), glass, quartz, or sapphire. It will be understood that other optical materials that are substantially transparent to infrared light are possible and contemplated.

[0063] In some embodiments, other portions of the rotatable housing 160 may be coated with or formed from an optically absorptive material, such as black tape, absorptive paint, carbon black, surfaces or materials treated with black anodization and / or micro-arc oxidation, and / or other types of optically absorptive, anti-reflective surfaces or materials.

[0064] The various elements of the system 100 may be arranged in different arrangements.For example, in an example embodiment, at least one of the light receiving axis 19 or the light transmitting axis 18 does not intersect the mirror rotation axis 131 .

[0065] The system 100 includes a controller 150. In some embodiments, the controller 150 includes at least one of a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). Additionally or alternatively, the controller 150 may include one or more processors 152 and a memory 154. The one or more processors 152 may include a general-purpose processor or a special-purpose processor (e.g., a digital signal processor, a graphics processor unit, etc.). The one or more processors 152 may be configured to execute computer-readable program instructions stored in the memory 154. In this way, the one or more processors 152 may execute the program instructions to provide at least some of the functions and operations described herein.

[0066] The memory 154 may include or take the form of one or more computer-readable storage media that can be read or accessed by the one or more processors 152. The one or more computer-readable storage media may include volatile and / or non-volatile storage components, such as optical, magnetic, organic, or other memory or disk storage devices, which may be integrated in whole or in part with at least one of the one or more processors 152. In some embodiments, the memory 154 may be implemented using a single physical device (e.g., an optical, magnetic, organic, or other memory or disk storage device), while in other embodiments, the memory 154 may be implemented using two or more physical devices. Thus, in one embodiment, the memory 154 may include a non-transitory computer-readable medium that stores instructions that, when executed by the one or more processors 152, cause the system 100 to perform at least some of the operations described herein.

[0067] As described above, the memory 154 may include computer-readable program instructions related to the operation of the system 100. As such, the memory 154 may include program instructions for performing or facilitating some or all of the operations or functions described herein.

[0068] For example, the operation may include causing the light emitter device 126 to emit light pulses. In such a scenario, the controller 150 may cause a pulse generator circuit associated with the light emitter device 126 to provide one or more current / voltage pulses to the light emitter device 126, which may cause the light emitter device 126 to provide the light pulses.

[0069] Operations may also include receiving at least a first portion of reflected light pulses (e.g., return light 16) from the field of view 17 as a detected light signal. For example, at least some of the light pulses (e.g., transmitted light 14) emitted from the light emitter device 126 via the optical window 162 may interact with an object 12 in the environment 10 within the field of view 17 to provide reflected light pulses or return light 16. At least a portion of the reflected light pulses may be received by at least one photodetector of the plurality of photodetectors 122. In turn, the given photodetector may provide a detected light signal, which may include a photocurrent signal or a photovoltage signal.

[0070] Furthermore, the operation may include determining a point cloud indicating the object 12 within the field of view 17 based on the detected light signals. In an exemplary embodiment, determining the point cloud may be performed by the controller 150. For example, the controller 150 may determine and accumulate a plurality of spatial points based on the corresponding flight time of each light pulse transmitted and received. Determining the point cloud may also be based on the elevation angle of the mirror assembly 130 and the azimuth angle of the rotatable base 110.

[0071] It should be understood that some or all of the operations described herein may be performed by a computing device remote from the controller 150 and / or other elements of the system 100 .

[0072] In various embodiments, system 100 may include at least one baffle. For example, system 100 may include at least one rotatable baffle 170 and / or at least one static baffle 172. In such a scenario, the at least one rotatable baffle 170 and / or at least one static baffle 172 may be configured to reduce stray light within optical cavity 120 (e.g., light that travels from light emitter device 126 internally to plurality of photodetectors 122 without first interacting with the environment surrounding system 100). In an example embodiment, static baffle 172 may include a light-impermeable material disposed between light receiving axis 19 and light transmitting axis 18. In some embodiments, rotatable baffle 170 may be coupled to mirror body 133 and may also include a light-impermeable material configured to reduce or eliminate stray light between the transmitter portion and the receiver portion of system 100. In other words, a first portion of mirror body 133 and a second portion of mirror body 133 may be separated by rotatable baffle 170. In such a scenario, rotatable baffle 170 may have a shape similar to a flat disk, although other shapes are also contemplated and possible. The rotatable baffle 170 may be centered about and perpendicular to the mirror rotation axis 131 .

[0073] In some embodiments, the system 100 may include an optical feedback system. As part of the optical feedback system, the transmitter 127 may be configured to transmit a plurality of light pulses toward the reflective surface 132 of the mirror assembly 130 during a period of rotation of the mirror body 133. In such a scenario, the mirror assembly 130 may be configured to (i) reflect at least a first light pulse of the plurality of light pulses into the environment 10 of the system 100, and (ii) reflect at least a second light pulse of the plurality of light pulses into the internal optical path 168. In some embodiments, the internal optical path 168 may include a rotatable baffle 170, a static baffle 172, and / or a baffle opening 174 in a gap between the rotatable baffle 170 and the static baffle 172.

[0074] In such a scenario, the plurality of photodetectors 122 of the receiver 121 can be configured to (i) detect reflected light pulses, including reflections of the first light pulse caused by the object 12 in the environment 10, and (ii) detect second light pulses received via the internal optical path 168. In various embodiments, the internal optical path 168 can be at least partially defined by one or more internal reflectors 180 that reflect the second light pulse toward the reflective surface 132 of the mirror assembly 130, such that the reflective surface 132 reflects the second light pulse toward the receiver 121.

[0075] Furthermore, in such a scenario, the controller 150 can be configured to determine the distance to the object 12 in the environment 10 based on the time when the transmitter 127 transmits the first light pulse, the time when the photodetector 122 detects the reflected light pulse, and the time when the photodetector 122 detects the second light pulse. In such a scenario, the first light pulse (and its corresponding reflected light pulse) can provide information indicating the distance to the object, and the second light pulse (and its corresponding reflected light pulse) can provide information indicating the feedback distance or the zero-length reference.

[0076] Figure 2 2. FIG. 2 shows a LIDAR device 200 mounted on a mounting structure 290 according to an example embodiment. For ease of illustration, Figure 2 The xyz axes are shown in .

[0077] Mounting structure 290 can be similar to outer structure 190. For example, mounting structure 290 can be formed from any solid material suitable for physically supporting LIDAR 200 while housing 160 and / or one or more components thereof rotate about axis 102.

[0078] like Figure 2As shown, the LIDAR 200 can be physically coupled to the mounting structure 290 via a receiving structure 291. In one example, the receiving structure 291 can include a curved wall of the mounting structure 290 that extends beyond the page to define a recess into which a portion of the LIDAR 200 can be inserted to physically couple the LIDAR 200 to the mounting structure 290. For example, a first portion of the LIDAR 200 can be physically connected to the mounting structure 290 at the receiving structure 291, and a bottom portion of the LIDAR 200 including the optical window 162 can remain outside of the receiving structure 291. Other examples of physically mounting the LIDAR 200 at a given location relative to the mounting structure 290 are also possible.

[0079] like Figure 2 As shown, calibration target 292 is disposed on a surface of mounting structure 290. For example, calibration target 292 can be similar to calibration target 191 described in connection with system 100. For purposes of illustration, calibration target 292 is shown extending horizontally (e.g., along the y-axis) along the surface of mounting structure 290 such that at least a portion (not shown) of calibration target 292 overlaps with LIDAR 200 (e.g., a portion behind LIDAR 200). However, in other examples, target 292 can alternatively be located at a different location along any surface of mounting structure 290 within the FOV scanned by LIDAR 200 as LIDAR (or a portion thereof) rotates about axis 102. Furthermore, target 292 can alternatively have a substantially uniform orientation relative to the surface of mounting structure 290. Figure 2 Therefore, it should be understood that various shapes, sizes and positions of the calibration target 292 are possible, and the target 292 is as shown. Figure 2 The illustration is for descriptive purposes only.

[0080] In some embodiments, LIDAR 200 can include an occlusion detection system. The occlusion detection system can be configured to provide information indicating the presence of an occluding object 222 associated with (e.g., coupled to or near) optical window 162.

[0081] It should be understood that although Figure 2The obstructing object 222 is shown as being disposed on an outer surface of the optical window 162, but other obstructing objects may be located elsewhere. In one example, the obstructing object 222 may alternatively comprise an external object coupled near the optical window 162. For example, a plastic bag or other object (not shown) may be coupled to a mounting structure or LIDAR or other external structure and may extend so that at least a portion of such external object appears at or near the LIDAR. In another example, the obstructing object 222 may alternatively comprise an obstruction incorporated into the optical window 162 itself, such as a crack or a blurred or opaque area of ​​the optical window 162. Other examples are also possible.

[0082] exist Figure 2 In the example shown, LIDAR 200 can scan at least a portion of mounting structure 290 that is disposed within a FOV scanned by LIDAR 200 (e.g., a portion where calibration target 292 is located, etc.). For example, as LIDAR 200 (or a portion thereof) rotates about axis 102, one or more of the light pulses emitted through optical window 162 (e.g., when optical window 162 faces the mounting structure, etc.) can propagate toward mounting structure 290. LIDAR 200 (or another computing system receiving data from LIDAR 200) can then detect the presence of occlusion 222, for example, by comparing the reflectivity characteristics of the scanned portion of mounting structure 290 to predetermined and / or otherwise expected reflectivity characteristics.

[0083] In some examples, the mounting structure 290 can reflect the "first light pulse" and the "second light pulse." In some embodiments, the corresponding reflected light pulses returned from the mounting structure 290 to the LIDAR 200 can be used as a basis for determining a reference time (e.g., a "zero time"), rather than or in addition to a given reference time determined based on, for example, a scan of an external calibration target and / or other known features in the environment. In some scenarios, due to the predetermined physical arrangement of the LIDAR 200 relative to the mounting structure 290, using the mounting structure to determine the reference time can improve the accuracy of the determined reference time (e.g., compared to a given reference time calculated using an external calibration target that is not necessarily physically coupled to the LIDAR 200).

[0084] 3. Example Vehicle

[0085] Figure 3A 、 Figure 3B 、 Figure 3C 、 Figure 3D and Figure 3E A vehicle 300 is shown according to an example embodiment. The vehicle 300 may be a semi-autonomous or fully autonomous vehicle. Figure 3A-Figure 3EThe vehicle 300 is shown as an automobile (e.g., a passenger car), but it should be understood that the vehicle 300 may include another type of autonomous vehicle, robot, or drone that can navigate within its environment using sensors and other information about its environment.

[0086] Vehicle 300 may include one or more sensor systems 302, 304, 306, 308, and 310. In some embodiments, sensor systems 302, 304, 306, 308, and 310 may include a LIDAR sensor having multiple light emitter devices arranged at a range of angles relative to a given plane (e.g., an xy plane).

[0087] One or more of sensor systems 302, 304, 306, 308, and 310 can be configured to rotate about an axis perpendicular to a given plane (e.g., the z-axis) to illuminate the environment surrounding vehicle 300 with light pulses. Based on detecting various aspects of the reflected light pulses (e.g., time of flight experienced, polarization, intensity, etc.), information about the environment can be determined.

[0088] In an example embodiment, sensor systems 302, 304, 306, 308, and 310 may be configured to provide corresponding point cloud information that may be associated with physical objects within the environment of vehicle 300. Although vehicle 300 and sensor systems 302, 304, 306, 308, and 310 are shown as including certain features, it should be understood that other types of sensor systems are also contemplated within the scope of the present disclosure.

[0089] Example embodiments may include a system having multiple light emitter devices. The system may include a transmitter block of a lidar device. For example, the system may correspond to (or may be included in) a lidar device of a vehicle (e.g., a car, truck, motorcycle, golf cart, aircraft, boat, etc.). Each of the multiple light emitter devices is configured to emit light pulses along a respective beam elevation angle. The respective beam elevation angles may be based on a reference angle or reference plane. In some embodiments, the reference plane may be based on an axis of motion of the vehicle 300.

[0090] Although a lidar system with a single light emitter device is described and illustrated herein, lidar systems with multiple light emitter devices (e.g., a light emitter device with multiple laser bars on a single laser die) are also contemplated. For example, light pulses emitted by one or more laser diodes can be controllably directed into the system's surrounding environment. The angle at which the light pulses are emitted can be adjusted by a scanning device (such as, for example, a mechanical scanning mirror and / or a rotary motor). For example, the scanning device can rotate in a reciprocating motion around a given axis and / or rotate around a vertical axis. In another embodiment, the light emitter device can emit light pulses into a spinning prism mirror that can cause the light pulses to be emitted into the environment based on the angle of the prism mirror when interacting with each light pulse. Additionally or alternatively, scanning optics and / or other types of opto-mechanical devices can scan the light pulses around the environment. Embodiments utilizing multiple fixed beams are also contemplated within the context of the present disclosure.

[0091] In some embodiments, a single light emitter device can emit light pulses according to a variable shot schedule and / or at a variable power per shot (power per shot / power-per-shot), as described herein. That is, the emission power and / or timing of each laser pulse or shot can be based on the corresponding elevation angle of each shot. In addition, the variable shot schedule can be based on providing a desired vertical spacing at a given distance from the lidar system or from the surface of a given vehicle supporting the lidar system (e.g., the front bumper). For example, when light pulses from a light emitter device are directed downward, the power per shot may be reduced because the expected maximum distance to the target is shorter. Conversely, light pulses emitted by a light emitter device at an elevation angle above a reference plane can have a relatively higher power per shot in order to provide a sufficient signal-to-noise ratio to adequately detect pulses traveling longer distances.

[0092] In some embodiments, the power / energy per lasing shot can be dynamically controlled for each lasing shot. In other embodiments, the power / energy per lasing shot can be controlled for a set of consecutive pulses (e.g., 10 optical pulses). In other words, the characteristics of the optical pulse train can be changed on a pulse-by-pulse basis and / or on a pulse-by-pulse basis.

[0093] although Figure 3A-Figure 3E Various lidar sensors are shown attached to the vehicle 300 , but it should be understood that the vehicle 300 may include other types of sensors, such as multiple optical systems (eg, cameras), radar, or ultrasonic sensors.

[0094] In an example embodiment, the vehicle 300 may include a lidar system (e.g., system 100) configured to emit light pulses into the environment of the vehicle 300 to provide information indicating objects within a default field of view. For example, the vehicle 300 may include an optical system (e.g., system 100) having a rotatable base (e.g., rotatable base 110) configured to rotate about a first axis (e.g., first axis 102). The optical system may also include a mirror assembly (e.g., mirror assembly 130). The mirror assembly may be configured to rotate about a mirror rotation axis. In some embodiments, the mirror rotation axis is substantially perpendicular to the first axis.

[0095] The optical system also includes an optical cavity (e.g., optical cavity 120) coupled to the rotatable base. In such a scenario, the optical cavity includes at least one light emitter device (e.g., light emitter device 126) and a light emitter lens (e.g., light emitter lens 128). The at least one light emitter device and the light emitter lens are arranged to define a light emission axis (e.g., light emission axis 18).

[0096] The optical system further includes a plurality of photodetectors (e.g., photodetector 122). In an exemplary embodiment, the plurality of photodetectors includes a set of two or more photodetectors corresponding to each of the at least one light emitter device. The optical system further includes a photodetector lens (e.g., photodetector lens 124). In such a scenario, the plurality of photodetectors and the photodetector lens are arranged to define a light receiving axis (e.g., light receiving axis 19). In some embodiments, at least one of the light receiving axis or the light emitting axis can form an oblique angle relative to the first axis.

[0097] In some embodiments, each set of two or more photodetectors may include a primary light detector (e.g., primary light detector 123) and a secondary light detector (e.g., secondary light detector 125). In such a scenario, the primary light detector is configured to receive a first portion of the return light emitted from a given light emitter device. In addition, the secondary light detector is configured to receive a second portion of the return light emitted from the given light emitter device.

[0098] In some embodiments, the first portion of the returned light may be at least an order of magnitude greater in photon flux than the second portion of the returned light.

[0099] 4. Example Method

[0100] Figure 41 and 2. A method 400 is shown according to an example embodiment. It will be understood that the method 400 may include fewer or more steps or blocks than those explicitly shown or disclosed herein. Furthermore, the respective steps or blocks of the method 400 may be performed in any order, and each step or block may be performed one or more times. In some embodiments, some or all of the blocks or steps of the method 400 may be performed by the controller 150 and / or other elements of the system 100, the LIDAR 200, and / or the vehicle 300, as described with reference to FIG. Figure 1 、 Figure 2 and / or Figure 3A-Figure 3E Shown and described.

[0101] Block 402 includes emitting a light pulse from a light emitter device coupled to a rotatable base, the light pulse initially interacting with a mirror assembly and then emitted toward an environment as emitted light.

[0102] Block 404 includes receiving return light from the environment, the return light initially interacting with the mirror assembly and then being detected by at least one primary light detector and one secondary light detector.

[0103] Block 406 includes determining a distance to an object in the environment based on a time of flight between the transmission time and the reception time.

[0104] In some embodiments, method 400 may further include rotating the rotatable base about a first axis, rotating the mirror assembly about a mirror rotation axis, and repeating the transmitting, receiving, and determining steps while the mirror assembly rotates to form a point cloud. The point cloud includes a plurality of distances or range data in a three-dimensional representation of the environment.

[0105] Figure 5 5. A method 500 is shown according to an example embodiment. It will be understood that the method 500 may include fewer or more steps or blocks than those explicitly shown or disclosed herein. Furthermore, the various steps or blocks of the method 500 may be performed in any order, and each step or block may be performed one or more times. In some embodiments, some or all of the blocks or steps of the method 500 may be performed by the controller 150 and / or other elements of the system 100, the LIDAR 200, and / or the vehicle 300, as described with respect to FIG. Figure 1 、 Figure 2 and Figure 3A-Figure 3E Shown and described.

[0106] At block 502 , method 500 includes scanning at least a portion of an external structure within a field of view of a LIDAR device.

[0107] In a first example, the external structure may correspond to a mounting structure, and the LIDAR device may be mounted to the mounting structure. Figure 2For example, LIDAR 200 can be mounted to mounting structure 290, which in turn can optionally mount LIDAR 200 to another system (not shown), such as vehicle 300. Thus, in this example, the LIDAR device can be physically coupled to an external structure (e.g., mounting structure 290) such that the LIDAR device is maintained at an offset position relative to the external structure. Figure 2 As shown, when the LIDAR 200 (or a portion thereof) is rotated about the axis 102, the LIDAR 200 and the mounting structure 290 may be physically connected in a particular relative arrangement.

[0108] In a second example, the external structure may correspond to any other structure that is physically coupled (directly or indirectly) to the LIDAR device such that the external structure is maintained at a predetermined offset position relative to the LIDAR 200. Figure 3A For example, the external structure may correspond to a portion of the vehicle 300 (or a portion thereof) that is within the FOV scanned by the LIDAR 310 (e.g., a body panel of the vehicle, a bumper of the vehicle, a fender of the vehicle, a rearview mirror of the vehicle, etc.). Thus, in this example, the LIDAR device may be physically coupled (e.g., indirectly) to the external structure (e.g., any portion of the vehicle having an exterior surface that is within the FOV of the LIDAR device) such that the LIDAR device is maintained at an offset position relative to the external structure. Return to Reference Figure 3A For example, the external structure may be a body panel of a vehicle, and the LIDAR device may be LIDAR 310 mounted to the vehicle at a specific mounting position. In this example, the body panel and LIDAR 310 may maintain a specific relative arrangement defined by the specific mounting position of LIDAR 310 relative to a given position of the body panel on the vehicle. Furthermore, in this example, the body panel (i.e., the external structure) and LIDAR 310 (i.e., the LIDAR device) may maintain the same specific relative arrangement if the vehicle 300 moves within the environment.

[0109] For ease of description, it is noted that the terms "mounting structure" and "external structure" may be used interchangeably in the description of the various blocks of method 500. However, it should be understood that some examples herein where the external structure is a mounting structure may alternatively be implemented using any other external structure physically coupled (directly or indirectly) to the LIDAR device (or vice versa) without departing from the scope of this disclosure.

[0110] The scanning at block 502 may involve sending light pulses (e.g., light 14) in different directions toward at least a portion of the external structure through an optical window (e.g., optical window 162). For example, a series of transmitted light pulses may be directed by LIDAR 200 to different directions, and thus, one or more of the transmitted light pulses may be directed (through optical window 162) toward the external structure (e.g., Figure 2 At least a portion of the mounting structure 290 shown is transmitted within the FOV of the LIDAR 200.

[0111] The scanning at block 502 may also involve receiving reflected light pulses (eg, light 16 ) through the optical window, including reflections of transmitted light pulses returning to the LIDAR device from external structures, consistent with the discussion above.

[0112] At block 504 , method 500 involves detecting, based at least on the scan in block 502 , the presence of an occlusion that at least partially obscures a scanning FOV of the LIDAR device.

[0113] For example, refer again to Figure 2 , the system of method 500 can determine that an occlusion 222 exists based on a scan indicating that the intensity of one or more reflected light pulses returned from mounting structure 290 is lower than an expected intensity. As another example, the system can determine that an occlusion exists in response to a scan indicating that the appearance, position, and / or other characteristics of an external structure indicated by the scan are different than expected. Other examples are also possible.

[0114] In some examples, method 500 involves comparing a reflectivity characteristic of the external structure indicated by the scan with a predetermined reflectivity characteristic. In these embodiments, detecting the presence of an occlusion at block 504 can be based on the comparison. For example, the scanned portion of the external structure can be associated with a predetermined characteristic measured prior to the scan and compared with the measurement indicated by the scan to determine whether an occlusion exists.

[0115] In one example, the predetermined reflectivity characteristic is based on a previous scan of the external structure by the LIDAR device. For example, the LIDAR 200 can be configured to repeatedly scan its FOV, and therefore, if the reflectivity characteristic indicated by the scan at block 502 is different from the predetermined reflectivity characteristic indicated by the previous scan, the LIDAR 200 or another system of the method 500 can detect an occlusion.

[0116] In another example, the predetermined reflectivity characteristic may be associated with one or more calibration targets disposed on at least a portion of the external structure. Figure 2For example, predetermined characteristics (eg, texture, pattern, etc.) of the calibration target 292 may be compared to the measured characteristics indicated by the scan at block 502 to determine if occlusions are present.

[0117] In some examples, method 500 involves determining whether an occlusion is located on the optical window based on one or more scans of the FOV by the LIDAR device. For example, one or more previous scans of the FOV may indicate a change in characteristics and / or appearance of external structures and / or other portions of the FOV compared to corresponding characteristics and / or appearance indicated by the scan of block 502.

[0118] In some examples, method 500 involves rotating the LIDAR device about an axis (eg, axis 102) during a rotation period, and the scanning at block 502 may occur during a first portion of the rotation period. Figure 2 For example, the first portion of the rotation period may correspond to a time period when LIDAR 200 is within an angular range about axis 102 within which light pulses emitted from optical window 162 are directed toward mounting structure 290 (or any other external structure physically coupled to LIDAR 200 at a predetermined offset therefrom). In some examples, method 500 involves scanning at least one object during the second portion of the rotation period.

[0119] In some examples, method 500 involves determining a reference time based on one or more time differences between a transmission time of one or more light pulses transmitted toward an external structure and one or more reception times of one or more reflected light pulses returning from the external structure to the LIDAR device. For example, instead of or in addition to calibrating the reference time using features in the environment of the LIDAR device, the reference time (e.g., a "zero time") can be calibrated based on a predetermined and / or known position of one or more calibration targets (e.g., calibration targets 192, 292, etc.) and / or the external structure itself.

[0120] In these examples, method 500 may also involve determining a distance to the at least one object based on a transmission time of a light pulse transmitted toward the at least one object, a reception time of a reflected light pulse returned from the at least one object to the LIDAR device, and a reference time. For example, the determined reference time may be used to calibrate a measured time difference associated with the at least one object, as discussed above.

[0121] In some examples, method 500 may involve detecting optical misalignment (or other defects) in a LIDAR device. For example, one or more components of LIDAR 200 (such as any of mirror assembly 130, mirror surface 132, optical cavity 120, receiver 121, optical window 162, or any other component of the LIDAR) may become deviated from their expected position and / or orientation. As an example of optical misalignment, a misaligned rotatable base 110 may rotate about an offset axis that is different from axis 102. Other examples of optical misalignment are also possible. In examples where such optical misalignment occurs, the actual direction of light pulses emitted from LIDAR 200 may differ from the expected direction associated with a properly aligned LIDAR configuration. Thus, in some examples, method 500 may involve detecting optical misalignment (or other defects) in a LIDAR device based on measuring the angle (e.g., about axis 102) of a detected external structure and / or one or more features thereon (e.g., calibration structure 292, etc.).

[0122] The arrangements shown in the accompanying drawings should not be considered limiting. It should be understood that other embodiments may include more or fewer of each element shown in a given drawing. In addition, some of the elements shown may be combined or omitted. Furthermore, the illustrative embodiments may include elements not shown in the accompanying drawings.

[0123] The steps or boxes representing the processing of information may correspond to circuits that can be configured to perform the specific logical functions of the methods or techniques described herein. Alternatively or additionally, the steps or boxes representing the processing of information may correspond to modules, segments, or portions of program code (including associated data). The program code may include one or more instructions that can be executed by a processor to implement specific logical functions or actions in the method or technique. The program code and / or associated data may be stored on any type of computer-readable medium, such as a storage device including a disk, hard drive, or other storage medium.

[0124] Computer-readable media can also include non-transitory computer-readable media, such as computer-readable media that store data in the short term, such as register memory, processor cache, and random access memory (RAM). Computer-readable media can also include non-transitory computer-readable media that store program code and / or data in the longer term. Therefore, computer-readable media can include auxiliary or permanent long-term storage devices, such as, for example, read-only memory (ROM), optical or magnetic disks, compact disk read-only memory (CD-ROM). Computer-readable media can also be any other volatile or non-volatile storage system. For example, computer-readable media can be considered to be computer-readable storage media or tangible storage devices.

[0125] While various examples and embodiments have been disclosed, other examples and embodiments will be apparent to those skilled in the art. The various disclosed examples and embodiments are for illustrative purposes only and are not intended to be limiting, with the true scope being indicated by the following claims.

Claims

1. A method comprising: Scanning, by a light detection and ranging (LIDAR) device physically coupled to the external structure, at least a portion of the external structure within a field of view (FOV) of the LIDAR device, wherein the scanning comprises: sending light pulses in different directions toward the external structure through the optical window, and receiving a reflected light pulse through the optical window, the reflected light pulse comprising a reflection of the transmitted light pulse returning from the external structure to the LIDAR device; and The presence of an occlusion at least partially obstructing a LIDAR device scanning the FOV is detected based at least on an appearance of the external structure indicated by a scan of at least a portion of the external structure being different than a predetermined appearance indicated by a previous scan.

2. The method according to claim 1, further comprising: A reflectivity characteristic of the external structure indicated by the scan is compared to a predetermined reflectivity characteristic, wherein detecting the presence of an occlusion is based on the comparison.

3. The method according to claim 2, wherein: The predetermined reflectivity characteristic is based on a previous scan of at least a portion of the external structure by a LIDAR device.

4. The method according to claim 2, wherein: At least a portion of the external structure scanned by the LIDAR device includes one or more calibration targets disposed on the external structure, and wherein the predetermined reflectivity characteristic is associated with the one or more calibration targets.

5. The method according to claim 1, further comprising: Based on one or more scans of the FOV by the LIDAR device, it is determined whether the occlusion is located on the optical window.

6. The method according to claim 1, further comprising: The LIDAR device is rotated about an axis during a rotation period, wherein scanning of at least a portion of the external structure occurs during a first portion of the rotation period.

7. The method according to claim 6, further comprising: During a second portion of the rotation period, at least one object separated from the external structure is scanned by the LIDAR device.

8. The method according to claim 7, further comprising: determining a reference time based on one or more time differences between one or more transmission times of one or more of the light pulses transmitted toward the external structure and one or more reception times of one or more of the reflected light pulses returning from the external structure to the LIDAR device; as well as The distance to the at least one object is determined based on a transmission time of a light pulse transmitted toward the at least one object, a reception time of a reflected light pulse returned from the at least one object to the LIDAR device, and a reference time.

9. The method according to claim 1, wherein The external structure includes a mounting structure coupled to a vehicle, and wherein the LIDAR device is mounted to the mounting structure.

10. A system comprising: Mounting structure; a light detection and ranging (LIDAR) device mounted to the mounting structure; Optical windows; one or more processors; as well as a data storage device storing instructions that, when executed by the one or more processors, cause the system to perform operations comprising: Scanning at least a portion of the mounting structure within a field of view (FOV) of the LIDAR device, wherein the scanning comprises: sending light pulses from the LIDAR device toward the mounting structure through the optical window in different directions, and receiving a reflected light pulse through the optical window, the reflected light pulse comprising a reflection of the transmitted light pulse returning from the mounting structure to the LIDAR device; and The presence of an occlusion at least partially obstructing scanning of the FOV by the LIDAR device is detected based at least on an appearance of the external structure indicated by a scan of at least a portion of the mounting structure being different than a predetermined appearance indicated by a previous scan.

11. The system according to claim 10, wherein: The operations further include: A reflectivity characteristic of the mounting structure indicated by the scan is compared to a predetermined reflectivity characteristic, wherein detecting the presence of an occlusion is based on the comparison.

12. The system according to claim 11, wherein The predetermined reflectivity characteristic is based on a previous scan of at least a portion of the mounting structure.

13. The system of claim 11, further comprising: One or more calibration targets are disposed on at least a portion of the mounting structure being scanned, wherein the predetermined reflectivity characteristic is associated with the one or more calibration targets.

14. The system according to claim 10, wherein: The mounting structure is coupled to a carrier.

15. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors, cause a system to perform operations comprising: Scanning at least a portion of the external structure within a field of view (FOV) of the external structure using a light detection and ranging (LIDAR) device physically coupled to the external structure, wherein the scanning comprises: sending light pulses in different directions toward the external structure through an optical window of the LIDAR device, and receiving a reflected light pulse through the optical window, the reflected light pulse comprising a reflection of the transmitted light pulse returning from the external structure to the LIDAR device; and The presence of an occlusion at least partially obstructing a LIDAR device scanning the FOV is detected based at least on an appearance of the external structure indicated by a scan of at least a portion of the external structure being different than a predetermined appearance indicated by a previous scan.

16. The non-transitory computer-readable medium of claim 15, wherein: The operations further include: A reflectivity characteristic of the external structure indicated by the scan is compared to a predetermined reflectivity characteristic, wherein detecting the presence of an occlusion is based on the comparison.

17. The non-transitory computer-readable medium of claim 15, wherein: The operations further include: Based on one or more scans of the FOV, it is determined whether an obstruction is located on the optical window.

18. The non-transitory computer-readable medium of claim 15, wherein: The operations further include: The LIDAR device is rotated about an axis during a rotation period, wherein scanning of at least a portion of the external structure occurs during a first portion of the rotation period.

19. The non-transitory computer-readable medium of claim 18, wherein: The operations further include: During a second portion of the rotation period, at least one object separated from the external structure is scanned using a LIDAR device.

20. The non-transitory computer-readable medium of claim 19, wherein: The operations further include: determining a reference time based on one or more time differences between one or more transmission times of one or more of the light pulses transmitted toward the external structure and one or more reception times of one or more of the reflected light pulses returning from the external structure to the LIDAR device; and The distance to the at least one object is determined based on a transmission time of a light pulse transmitted toward the at least one object, a reception time of a reflected light pulse returned from the at least one object to the LIDAR device, and a reference time.

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