Patent Application
20220113429
The present application claims priority to Russian Patent Application No. 2020133316, entitled “Lidar Systems and Methods”, filed Oct. 9, 2020, the entirety of which is incorporated herein by reference.
The present technology relates generally to Light Detection and Ranging (LiDAR) systems and methods for detecting objects in a surrounding environment of an autonomous vehicle; and in particular, to LiDAR systems and methods for detecting objects in a desired region of interest in the surrounding environment.
Several computer-based navigation systems that are configured for aiding navigation and/or control of vehicles have been proposed and implemented in the prior art. These systems range from more basic map-aided localization-based solutions—i.e. use of a computer system to assist a driver in navigating a route from a starting point to a destination point; to more complex ones such as computer-assisted and/or driver-autonomous driving systems.
Some of these systems are implemented as what is commonly known as a “cruise control” system. Within these systems, the computer system boarded on the vehicles maintains a user-set speed of the vehicle. Some of the cruise control systems implement an “intelligent distance control” system, whereby the user can set up a distance to a potential car in front (such as, select a value expressed in a number of vehicles) and the computer system adjusts the speed of the vehicle at least in part based on the vehicle approaching the potential vehicle in front within the pre-defined distance. Some of the cruise control systems are further equipped with collision control systems, which systems, upon detection of the vehicle (or other obstacles) in front of the moving vehicle, slow down or stop the vehicle.
Some of the more advanced systems provide for a fully autonomous driving of the vehicle without direct control from the operator (i.e. the driver). These autonomously driven vehicles include systems that can cause the vehicle to accelerate, brake, stop, change lane and self-park.
One of the main technical challenges in implementing the above systems is the ability to detect objects located around the vehicle. In one example, the systems may need the ability to detect the vehicle in front of the present vehicle (the present vehicle having the system onboard), which vehicle in front may pose a risk/danger to the present vehicle and may require the system to take a corrective measure, be it braking or otherwise changing speed, stopping or changing lanes. In another example, the systems may need to detect a pedestrian or animal crossing in front of the vehicle or otherwise in a surrounding environment of the vehicle.
LiDAR-based object detection generally comprises transmitting beams of light towards a region of interest, and detecting reflected light beams, such as from objects in the region of interest, to generate a representation of the region of interest including any objects. Lasers emitting pulses of light within a narrow wavelength are often used as the radiation (light) source. The position and distance of the object can be computed using inter alia Time of Flight calculations of the emitted and detected light beam. By computing such positions as “data points”, a digital multi-dimensional representation of the surroundings can be generated.
Generally, as for the physics of LiDAR-based object detection, one approach currently known in the art is based on utilizing a pulsed emission and is referred to as Time of Flight (ToF) LiDAR systems. In ToF LiDAR systems, each LiDAR sensor emits a short pulse of a predetermined wavelength and further registers time that it takes for the pulse to scatter from a surrounding object and to return to the respective LiDAR sensor. By rotating the ToF LiDAR system, positioned at the top of the vehicle, comprising a plurality of such LiDAR sensors, by 360 degrees, a 3D representation of the surroundings of the vehicle can be generated.
The 3D representation is formed in part by reflected beams received by the LIDAR which generates data points representative of the surrounding objects. These points form clouds that represent the surrounding environment and form a 3D map. Each point in the point cloud is associated with coordinates in a coordinate space. Additionally, each point can be associated with some additional information such as the distance to the object from the self-driving vehicle. Other information may be associated with the points in the point cloud.
The more points with acceptable quality are obtained, the better. In this case, a computer of the self-driving vehicle can perform tasks of various cognitive complexity using the point cloud, e.g. filtering, clustering or sampling of the points, merging of the point clouds, recognizing the object, etc. The quality of performing these separate tasks affects the general quality of localization and navigation of the self-driving vehicle. Precise information on the surrounding objects improves the safety of driving.
Under certain circumstances, the distribution of the point clouds may not be homogenous, leading to a higher density of points in some regions of interest, and a lower density of points in other regions of interest. This may have resultant differences in sensitivity of object detection from region of interest to region of interest.
Therefore, there is a need for systems and methods which avoid, reduce or overcome the limitations of the prior art.
In order to address the above-identified problem, certain prior art approaches have been proposed.
United States Patent Application Publication US2012249996A1 describes a laser radar having a first scanning member scans a laser beam in a virtual plane passing through an axis. A control means controls displacements of the first scanning member to change a scan beam angle in the plane. A second scanning member deflects the scanned laser beam and again scans the deflected laser beam toward an external space. A light collecting means collects reflected light. A driving means rotates both the second scanning member and the light collecting means about the axis. The second scanning member has a deflecting surface to deflect the laser beam. The deflecting surface is formed around the axis and has a plurality of reflecting surfaces coaxially arranged centering on the axis. The reflecting surfaces have different inclinations with respect to a horizontal plane perpendicular to the axis.
United States Patent Application Publication US2013033732A1 describes a rotating scanning platform comprising a rotating body and two or more suspension flexures to support the rotating body at a first end of respective suspension flexures, wherein the suspension flexures have a length that is greater than a radius of the rotating body, and the suspension flexures are disposed at an offset from a center of rotation of the rotating body. The suspension flexures are fixed, respectively, to a substrate at a second end at a location that is closer to the center of rotation than to the first end of a respective suspension flexure to allow the rotating body to rotate about the center of rotation with generally linear rotation in response to a drive signal.
United States Patent Application Publication US2019265338A1 describes an emitter device for an optical detection apparatus of a motor vehicle, which is designed to scan a surrounding region of the motor vehicle by means of a light beam, and which comprises a light source for emitting the light beam and a deflection unit, wherein the deflection unit is designed to deflect the light beam emitted onto the deflection unit by the light source at different scanning angles (a), wherein the deflection unit comprises a freeform mirror. The freeform mirror comprises at least two surface elements having different angles of inclination and is designed to reflect the light beam in order to generate a predetermined setpoint field of view of the emitter device at predetermined setpoint values (−α3, −α2, −α1, α0, +α1, +α2, +α3) for the scanning angle (α), said setpoint values corresponding to the angles of inclination. The invention additionally relates to an optical detection apparatus, a motor vehicle comprising at least one optical detection apparatus, and to a method for generating a setpoint field of view for an emitter device of an optical detection apparatus of a motor vehicle.
In accordance with a first broad aspect of the present technology, there is provided A LIDAR system for detecting objects in a surrounding environment of an autonomous vehicle, the LIDAR system comprising: a radiation source configured to emit output beams along an internal emission pathway; a scanner, positionable along the internal emission pathway and configured to direct the output beams onto a field of view of the surrounding environment as a plurality of data points in a scanning pattern, wherein the scanner comprises: a scanning face having a non-planar profile and comprising a plurality of reflective surface segments, each reflective surface segment having: a given position on the scanning face, and a given angle relative to a reference for reflecting the output beams as a propagating beam with a given propagating angle; wherein the given position and the given angle of each reflective surface segment is configured to modulate a distribution of the data points in the scanning pattern across the field of view.
In certain embodiments, the given position and the given angle of at least some of the plurality of reflective surface segments is configured to generate a homogenous distribution of the data points throughout at least a portion of the scanning pattern.
In certain embodiments, the given position and the given angle of at least some of the plurality of reflective surface segments is configured to generate a homogenous density of the data points throughout an outer portion and a central portion of the scanning pattern.
In certain embodiments, the given position and the given angle of at least some of the plurality of reflective surface segments is configured to compensate for a difference in scanning frequency at an end of the scanning face compared to at a center of the scanning face in order to modulate a distribution of the data points.
In certain embodiments, at least one reflective surface segment of the plurality of reflecting surface segments is linear.
In certain embodiments, at least one reflective surface segment of the plurality of reflecting surface segments is curvilinear.
In certain embodiments, the plurality of reflective surface segments are configured to render the scanning face with a convex configuration.
In certain embodiments, the plurality of reflective surface segments are configured to render the scanning face with a concave configuration.
In certain embodiments, the scanner is an oscillating galvo mirror.
In certain embodiments, the scanner is a rotating prism and the scanning face is a face of the rotating prism.
In certain embodiments, the scanner comprises a rotating prism and a mirror, the scanning face comprising at least one face of the rotating prism and at least one face of the mirror.
In certain embodiments, at least two of the plurality of reflective surface segments are angularly off-set from one another.
In certain embodiments, at least two of the plurality of the reflective surface segments are made of different materials to impart different optical properties on the respective propagating beams.
In certain embodiments, the plurality of the reflective surface segments are configured to form a linear rounded surface.
In certain embodiments, the LiDAR system further comprises a controller communicatively coupled to the radiation source and the scanner, the controller being configured to cause a given output beam to be incident on a given reflective surface segment.
In certain embodiments, the controller is configured to move the scanner for selective contact of the output beams with a given reflective surface segment.
In certain embodiments, the controller is configured to move the output beams for selective contact of the output beams with a given segment reflective surface.
In certain embodiments, the LIDAR system further comprises a receiver for receiving reflected propagating beams from the field of view.
From another aspect, there is provided a method for detecting objects in a surrounding environment of an autonomous vehicle, the method executable by a controller which is communicatively coupled to a radiation source and a scanner of a LIDAR system, the method comprising: causing the radiation source to emit output beams along an internal emission pathway of the LIDAR system; causing the scanner to direct the output beams onto a field of view (FOV) within the surrounding environment, the scanner comprising: a scanning face having a non-planar profile and comprising a plurality of reflective surface segments having: a given position on the scanning face, and a given angle relative to a reference for reflecting the output beams as a propagating beam with a given propagating angle; wherein the given position and the given angle of at least some of the plurality of reflective surface segments is configured to modulate the propagating angle of the propagating beam to modulate a distribution of the data points in the scanning pattern across the field of view.
In certain embodiments, the method further comprises a controller communicatively coupled to the radiation source and the scanner, the controller being configured to cause a given output beam to be incident on a given reflective surface segment.
From another aspect, there is provided a method for determining a modulated configuration of a scanner unit for providing a homogenous scanning pattern. The method comprises a controller determining a preliminary scanning pattern generated by a preliminary scanning face of the scanner unit; if the preliminary scanning pattern is not homogenous, the method further comprises the controller determining a desired modulation of a given propagating angle of a given propagating beam to create the homogenous scanning pattern; determining which portion of the preliminary scanning face of the scanner unit the output beam will be incident to be reflected as the given propagating beam; and adjusting an angle of the identified portion of the preliminary scanning face to achieve the desired modulation of the given propagating beam.
In the context of the present specification, the term “light source” broadly refers to any device configured to emit radiation such as a radiation signal in the form of a beam, for example, without limitation, a light beam including radiation of one or more respective wavelengths within the electromagnetic spectrum. In one example, the light source can be a “laser source”. Thus, the light source could include a laser such as a solid-state laser, laser diode, a high power laser, or an alternative light source such as, a light emitting diode (LED)-based light source. Some (non-limiting) examples of the laser source include: a Fabry-Perot laser diode, a quantum well laser, a distributed Bragg reflector (DBR) laser, a distributed feedback (DFB) laser, a fiber-laser, or a vertical-cavity surface-emitting laser (VCSEL). In addition, the laser source may emit light beams in differing formats, such as light pulses, continuous wave (CW), quasi-CW, and so on. In some non-limiting examples, the laser source may include a laser diode configured to emit light at a wavelength between about 650 nm and 1150 nm. Alternatively, the light source may include a laser diode configured to emit light beams at a wavelength between about 800 nm and about 1000 nm, between about 850 nm and about 950 nm, between about 1300 nm and about 1600 nm, or in between any other suitable range. Unless indicated otherwise, the term “about” with regard to a numeric value is defined as a variance of up to 10% with respect to the stated value.
In the context of the present specification, an “output beam” may also be referred to as a radiation beam, such as a light beam, that is generated by the radiation source and is directed downrange towards a region of interest. The output beam may have one or more parameters such as: beam duration, beam angular dispersion, wavelength, instantaneous power, photon density at different distances from light source, average power, beam power intensity, beam width, beam repetition rate, beam sequence, pulse duty cycle, wavelength, or phase etc. The output beam may be unpolarized or randomly polarized, may have no specific or fixed polarization (e.g., the polarization may vary with time), or may have a particular polarization (e.g., linear polarization, elliptical polarization, or circular polarization).
In the context of the present specification, an “input beam” is radiation or light entering the system, generally after having been reflected from one or more objects in the ROI. The “input beam” may also be referred to as a radiation beam or light beam. By reflected is meant that at least a portion of the output beam incident on one or more objects in the ROI, bounces off the one or more objects. The input beam may have one or more parameters such as: time-of-flight (i.e., time from emission until detection), instantaneous power (e.g., power signature), average power across entire return pulse, and photon distribution/signal over return pulse period etc. Depending on the particular usage, some radiation or light collected in the input beam could be from sources other than a reflected output beam. For instance, at least some portion of the input beam could include light-noise from the surrounding environment (including scattered sunlight) or other light sources exterior to the present system.
In the context of the present specification, the term “surroundings” or “environment” of a given vehicle refers to an area or a volume around the given vehicle including a portion of a current environment thereof accessible for scanning using one or more sensors mounted on the given vehicle, for example, for generating a 3D map of the such surroundings or detecting objects therein.
In the context of the present specification, a “Region of Interest” may broadly include a portion of the observable environment of a LiDAR system in which the one or more objects may be detected. It is noted that the region of interest of the LiDAR system may be affected by various conditions such as but not limited to: an orientation of the LiDAR system (e.g. direction of an optical axis of the LiDAR system); a position of the LiDAR system with respect to the environment (e.g. distance above ground and adjacent topography and obstacles); operational parameters of the LiDAR system (e.g. emission power, computational settings, defined angles of operation), etc. The ROI of LIDAR system may be defined, for example, by a plane angle or a solid angle. In one example, the ROI may also be defined within a certain distance range (e.g. up to 200 m or so).
In the context of the present specification, a “server” is a computer program that is running on appropriate hardware and is capable of receiving requests (e.g. from electronic devices) over a network, and carrying out those requests, or causing those requests to be carried out. The hardware may be implemented as one physical computer or one physical computer system, but neither is required to be the case with respect to the present technology. In the present context, the use of the expression a “server” is not intended to mean that every task (e.g. received instructions or requests) or any particular task will have been received, carried out, or caused to be carried out, by the same server (i.e. the same software and/or hardware); it is intended to mean that any number of software elements or hardware devices may be involved in receiving/sending, carrying out or causing to be carried out any task or request, or the consequences of any task or request; and all of this software and hardware may be one server or multiple servers, both of which are included within the expression “at least one server”.
In the context of the present specification, “electronic device” is any computer hardware that is capable of running software appropriate to the relevant task at hand. In the context of the present specification, the term “electronic device” implies that a device can function as a server for other electronic devices, however it is not required to be the case with respect to the present technology. Thus, some (non-limiting) examples of electronic devices include self-driving unit, personal computers (desktops, laptops, netbooks, etc.), smart phones, and tablets, as well as network equipment such as routers, switches, and gateways. It should be understood that in the present context the fact that the device functions as an electronic device does not mean that it cannot function as a server for other electronic devices.
In the context of the present specification, the expression “information” includes information of any nature or kind whatsoever capable of being stored in a database. Thus information includes, but is not limited to visual works (e.g. maps), audiovisual works (e.g. images, movies, sound records, presentations etc.), data (e.g. location data, weather data, traffic data, numerical data, etc.), text (e.g. opinions, comments, questions, messages, etc.), documents, spreadsheets, etc.
In the context of the present specification, a “database” is any structured collection of data, irrespective of its particular structure, the database management software, or the computer hardware on which the data is stored, implemented or otherwise rendered available for use. A database may reside on the same hardware as the process that stores or makes use of the information stored in the database or it may reside on separate hardware, such as a dedicated server or plurality of servers.
In the context of the present specification, the words “first”, “second”, “third”, etc. have been used as adjectives only for the purpose of allowing for distinction between the nouns that they modify from one another, and not for the purpose of describing any particular relationship between those nouns. Further, as is discussed herein in other contexts, reference to a “first” element and a “second” element does not preclude the two elements from being the same actual real-world element.
Implementations of the present technology each have at least one of the above-mentioned object and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present technology that have resulted from attempting to attain the above-mentioned object may not satisfy this object and/or may satisfy other objects not specifically recited herein.
Additional and/or alternative features, aspects and advantages of implementations of the present technology will become apparent from the following description, the accompanying drawings and the appended claims.
These and other features, aspects and advantages of the present technology will become better understood with regard to the following description, appended claims and accompanying drawings where:
The examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the present technology and not to limit its scope to such specifically recited examples and conditions. It will be appreciated that those skilled in the art may devise various arrangements which, although not explicitly described or shown herein, nonetheless embody the principles of the present technology and are included within its spirit and scope.
Furthermore, as an aid to understanding, the following description may describe relatively simplified implementations of the present technology. As persons skilled in the art would understand, various implementations of the present technology may be of a greater complexity.
In some cases, what are believed to be helpful examples of modifications to the present technology may also be set forth. This is done merely as an aid to understanding, and, again, not to define the scope or set forth the bounds of the present technology. These modifications are not an exhaustive list, and a person skilled in the art may make other modifications while nonetheless remaining within the scope of the present technology. Further, where no examples of modifications have been set forth, it should not be interpreted that no modifications are possible and/or that what is described is the sole manner of implementing that element of the present technology.
Moreover, all statements herein reciting principles, aspects, and implementations of the technology, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof, whether they are currently known or developed in the future. Thus, for example, it will be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the present technology. Similarly, it will be appreciated that any flowcharts, flow diagrams, state transition diagrams, pseudo-code, and the like represent various processes which may be substantially represented in computer-readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.
The functions of the various elements shown in the figures, including any functional block labeled as a “processor”, may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read-only memory (ROM) for storing software, random access memory (RAM), and non-volatile storage. Other hardware, conventional and/or custom, may also be included.
Software modules, or simply modules which are implied to be software, may be represented herein as any combination of flowchart elements or other elements indicating performance of process steps and/or textual description. Such modules may be executed by hardware that is expressly or implicitly shown.
With these fundamentals in place, we will now consider some non-limiting examples to illustrate various implementations of aspects of the present technology.
Referring initially to
Communication between the various components of the computer system 100 may be enabled by one or more internal and/or external buses (not shown) (e.g. a PCI bus, universal serial bus, IEEE 1394 “Firewire” bus, SCSI bus, Serial-ATA bus, etc.), to which the various hardware components are electronically coupled. According to embodiments of the present technology, the solid-state drive 120 stores program instructions suitable for being loaded into the memory 130 and executed by the processor 110 for determining a presence of an object. For example, the program instructions may be part of a vehicle control application executable by the processor 110. It is noted that the computer system 100 may have additional and/or optional components (not depicted), such as network communication modules, localization modules, and the like.
With reference to
In some non-limiting embodiments of the present technology, the networked computing environment 200 could include a GPS satellite (not depicted) transmitting and/or receiving a GPS signal to/from the electronic device 210. It will be understood that the present technology is not limited to GPS and may employ a positioning technology other than GPS. It should be noted that the GPS satellite can be omitted altogether.
The vehicle 220, to which the electronic device 210 is associated, could be any transportation vehicle, for leisure or otherwise, such as a private or commercial car, truck, motorbike or the like. Although the vehicle 220 is depicted as being a land vehicle, this may not be the case in each and every non-limiting embodiment of the present technology. For example, in certain non-limiting embodiments of the present technology, the vehicle 220 may be a watercraft, such as a boat, or an aircraft, such as a flying drone.
The vehicle 220 may be user operated or a driver-less vehicle. In some non-limiting embodiments of the present technology, it is contemplated that the vehicle 220 could be implemented as a Self-Driving Car (SDC). It should be noted that specific parameters of the vehicle 220 are not limiting, these specific parameters including for example: vehicle manufacturer, vehicle model, vehicle year of manufacture, vehicle weight, vehicle dimensions, vehicle weight distribution, vehicle surface area, vehicle height, drive train type (e.g. 2× or 4×), tire type, brake system, fuel system, mileage, vehicle identification number, and engine size.
According to the present technology, the implementation of the electronic device 210 is not particularly limited. For example, the electronic device 210 could be implemented as a vehicle engine control unit, a vehicle CPU, a vehicle navigation device (e.g. TomTom™, Garmin™), a tablet, a personal computer built into the vehicle 220, and the like. Thus, it should be noted that the electronic device 210 may or may not be permanently associated with the vehicle 220. Additionally or alternatively, the electronic device 210 could be implemented in a wireless communication device such as a mobile telephone (e.g. a smart-phone or a radio-phone). In certain embodiments, the electronic device 210 has a display 270.
The electronic device 210 could include some or all of the components of the computer system 100 depicted in
In some non-limiting embodiments of the present technology, the communication network 240 is the Internet. In alternative non-limiting embodiments of the present technology, the communication network 240 can be implemented as any suitable local area network (LAN), wide area network (WAN), a private communication network or the like. It should be expressly understood that implementations for the communication network 240 are for illustration purposes only. A communication link (not separately numbered) is provided between the electronic device 210 and the communication network 240, the implementation of which will depend, inter alia, on how the electronic device 210 is implemented. Merely as an example and not as a limitation, in those non-limiting embodiments of the present technology where the electronic device 210 is implemented as a wireless communication device such as a smartphone or a navigation device, the communication link can be implemented as a wireless communication link. Examples of wireless communication links may include, but are not limited to, a 3G communication network link, a 4G communication network link, and the like. The communication network 240 may also use a wireless connection with the server 235.
In some embodiments of the present technology, the server 235 is implemented as a computer server and could include some or all of the components of the computer system 100 of
In some non-limiting embodiments of the present technology, the processor 110 of the electronic device 210 could be in communication with the server 235 to receive one or more updates. Such updates could include, but are not limited to, software updates, map updates, routes updates, weather updates, and the like. In some non-limiting embodiments of the present technology, the processor 110 can also be configured to transmit to the server 235 certain operational data, such as routes travelled, traffic data, performance data, and the like. Some or all such data transmitted between the vehicle 220 and the server 235 may be encrypted and/or anonymized.
It should be noted that a variety of sensors and systems may be used by the electronic device 210 for gathering information about surroundings 250 of the vehicle 220. As seen in
In one example, the plurality of sensor systems 280 may include various optical systems including, inter alia, one or more camera-type sensor systems that are mounted to the vehicle 220 and communicatively coupled to the processor 110 of the electronic device 210. Broadly speaking, the one or more camera-type sensor systems may be configured to gather image data about various portions of the surroundings 250 of the vehicle 220. In some cases, the image data provided by the one or more camera-type sensor systems could be used by the electronic device 210 for performing object detection procedures. For example, the electronic device 210 could be configured to feed the image data provided by the one or more camera-type sensor systems to an Object Detection Neural Network (ODNN) that has been trained to localize and classify potential objects in the surroundings 250 of the vehicle 220.
In another example, the plurality of sensor systems 280 could include one or more radar-type sensor systems that are mounted to the vehicle 220 and communicatively coupled to the processor 110. Broadly speaking, the one or more radar-type sensor systems may be configured to make use of radio waves to gather data about various portions of the surroundings 250 of the vehicle 220. For example, the one or more radar-type sensor systems may be configured to gather radar data about potential objects in the surroundings 250 of the vehicle 220, such data potentially being representative of a distance of objects from the radar-type sensor system, orientation of objects, velocity and/or speed of objects, and the like.
It should be noted that the plurality of sensor systems 280 could include additional types of sensor systems to those non-exhaustively described above and without departing from the scope of the present technology.
According to the present technology and as is illustrated in
Depending on the embodiment, the vehicle 220 could include more or fewer LiDAR systems 300 than illustrated. Depending on the particular embodiment, choice of inclusion of particular ones of the plurality of sensor systems 280 could depend on the particular embodiment of the LiDAR system 300. The LiDAR system 300 could be mounted, or retrofitted, to the vehicle 220 in a variety of locations and/or in a variety of configurations.
For example, depending on the implementation of the vehicle 220 and the LiDAR system 300, the LiDAR system 300 could be mounted on an interior, upper portion of a windshield of the vehicle 220. Nevertheless, as illustrated in
In some non-limiting embodiments, such as that of
In some non-limiting embodiments of the present technology, such as that of
Irrespective of the specific location and/or the specific configuration of the LiDAR system 300, it is configured to capture data about the surroundings 250 of the vehicle 220 used, for example, for building a multi-dimensional map of objects in the surroundings 250 of the vehicle 220. Details relating to the configuration of the LiDAR systems 300 to capture the data about the surroundings 250 of the vehicle 220 will now be described.
It should be noted that although in the description provided herein the LiDAR system 300 is implemented as a Time of Flight LiDAR system—and as such, includes respective components suitable for such implementation thereof—other implementations of the LiDAR system 300 are also possible without departing from the scope of the present technology. For example, in certain non-limiting embodiments of the present technology, the LiDAR system 300 may also be implemented as a Frequency-Modulated Continuous Wave (FMCW) LiDAR system according to one or more implementation variants and based on respective components thereof as disclosed in a co-owned United States patent application filed on May 25, 2021 bearing Ser. No. 17/329,255 entitled “LiDAR DETECTION METHODS AND SYSTEMS”; the content of which is hereby incorporated by reference in its entirety.
With reference to
Broadly speaking, the LiDAR system 300 includes a variety of internal components including, but not limited to: (i) a light source 302 (also referred to as a “laser source” or a “radiation source”), (ii) a beam splitting element 304, (iii) a scanner unit 308 (also referred to as a “scanner assembly”), (iv) a receiving unit 306 (also referred to herein as a “detection system”, “receiving assembly”, or a “detector”), and (v) a controller 310. It is contemplated that in addition to the components non-exhaustively listed above, the LiDAR system 300 could include a variety of sensors (such as, for example, a temperature sensor, a moisture sensor, etc.) which are omitted from
In certain non-limiting embodiments of the present technology, one or more of the internal components of the LiDAR system 300 are disposed in a common housing 330 as depicted in
Generally speaking, the LiDAR system 300 operates as follows: the light source 302 of the LiDAR system 300 emits pulses of light, forming an output beam 314; the scanner unit 308 scans the output beam 314 across the surroundings 250 of the vehicle 220 for locating/capturing data of a priori unknown objects (such as an object 320) therein, for example, for generating a multi-dimensional map of the surroundings 250 where objects (including the object 320) are represented in a form of one or more data points. The light source 302 and the scanner unit 308 will be described in more detail below.
As certain non-limiting examples, the object 320 may include all or a portion of a person, vehicle, motorcycle, truck, train, bicycle, wheelchair, pushchair, pedestrian, animal, road sign, traffic light, lane marking, road-surface marking, parking space, pylon, guard rail, traffic barrier, pothole, railroad crossing, obstacle in or near a road, curb, stopped vehicle on or beside a road, utility pole, house, building, trash can, mailbox, tree, any other suitable object, or any suitable combination of all or part of two or more objects.
Further, let it be assumed that the object 320 is located at a distance 318 from the LiDAR system 300. Once the output beam 314 reaches the object 320, the object 320 generally reflects at least a portion of light from the output beam 314, and some of the reflected light beams may return back towards the LiDAR system 300, to be received in the form of an input beam 316. By reflecting, it is meant that at least a portion of light beam from the output beam 314 bounces off the object 320. A portion of the light beam from the output beam 314 may be absorbed or scattered by the object 320.
Accordingly, the input beam 316 is captured and detected by the LiDAR system 300 via the receiving unit 306. In response, the receiving unit 306 is then configured to generate one or more representative data signals. For example, the receiving unit 306 may generate an output electrical signal (not depicted) that is representative of the input beam 316. The receiving unit 306 may also provide the so-generated electrical signal to the controller 310 for further processing. Finally, by measuring a time between emitting the output beam 314 and receiving the input beam 316 the distance 318 to the object 320 is calculated by the controller 310.
As will be described in more detail below, the beam splitting element 304 is utilized for directing the output beam 314 from the light source 302 to the scanner unit 308 and for directing the input beam 316 from the scanner unit to the receiving unit 306.
Use and implementations of these components of the LiDAR system 300, in accordance with certain non-limiting embodiments of the present technology, will be described immediately below.
The light source 302 is communicatively coupled to the controller 310 and is configured to emit light having a given operating wavelength. To that end, in certain non-limiting embodiments of the present technology, the light source 302 could include at least one laser pre-configured for operation at the given operating wavelength. The given operating wavelength of the light source 302 may be in the infrared, visible, and/or ultraviolet portions of the electromagnetic spectrum. For example, the light source 302 may include at least one laser with an operating wavelength between about 650 nm and 1150 nm. Alternatively, the light source 302 may include a laser diode configured to emit light at a wavelength between about 800 nm and about 1000 nm, between about 850 nm and about 950 nm, or between about 1300 nm and about 1600 nm. In certain other embodiments, the light source 302 could include a light emitting diode (LED).
The light source 302 of the LiDAR system 300 is generally an eye-safe laser, or put another way, the LiDAR system 300 may be classified as an eye-safe laser system or laser product. Broadly speaking, an eye-safe laser, laser system, or laser product may be a system with some or all of: an emission wavelength, average power, peak power, peak intensity, pulse energy, beam size, beam divergence, exposure time, or scanned output beam such that emitted light from this system presents little or no possibility of causing damage to a person's eyes.
According to certain non-limiting embodiments of the present technology, the operating wavelength of the light source 302 may lie within portions of the electromagnetic spectrum that correspond to light produced by the Sun. Therefore, in some cases, sunlight may act as background noise, which can obscure the light signal detected by the LiDAR system 300. This solar background noise can result in false-positive detections and/or may otherwise corrupt measurements of the LiDAR system 300. Although it may be feasible in some cases to increase a Signal-to-Noise Ratio (SNR) of the LiDAR system 300 by increasing the power level of the output beam 314, this may not be desirable in at least some situations. For example, it may not in some implementations be desirable to increase power levels of the output beam 314 to levels beyond eye-safe thresholds.
The light source 302 includes a pulsed laser configured to produce, emit, or radiate pulses of light with a certain pulse duration. For example, in some non-limiting embodiments of the present technology, the light source 302 may be configured to emit pulses with a pulse duration (e.g., pulse width) ranging from 10 ps to 100 ns. In other non-limiting embodiments of the present technology, the light source 302 may be configured to emit pulses at a pulse repetition frequency of approximately 100 kHz to 5 MHz or a pulse period (e.g., a time between consecutive pulses) of approximately 200 ns to 10 μs. Overall, however, the light source 302 can generate the output beam 314 with any suitable average optical power, and the output beam 314 may include optical pulses with any suitable pulse energy or peak optical power for a given application.
In some non-limiting embodiments of the present technology, the light source 302 could include one or more laser diodes, including but not limited to: Fabry-Perot laser diode, a quantum well laser, a distributed Bragg reflector (DBR) laser, a distributed feedback (DFB) laser, or a vertical-cavity surface-emitting laser (VCSEL). Just as examples, a given laser diode operating in the light source 302 may be an aluminum-gallium-arsenide (AlGaAs) laser diode, an indium-gallium-arsenide (InGaAs) laser diode, or an indium-gallium-arsenide-phosphide (InGaAsP) laser diode, or any other suitable laser diode. It is also contemplated that the light source 302 may include one or more laser diodes that are current-modulated to produce optical pulses.
In some non-limiting embodiments of the present technology, the light source 302 is generally configured to emit the output beam 314 that is a collimated optical beam, but it is contemplated that the beam produced could have any suitable beam divergence for a given application. Broadly speaking, divergence of the output beam 314 is an angular measure of an increase in beam cross-section size (e.g., a beam radius or beam diameter) as the output beam 314 travels away from the light source 302 or the LiDAR system 300. In some non-limiting embodiments of the present technology, the output beam 314 may have a substantially circular cross-section.
It is also contemplated that the output beam 314 emitted by light source 302 could be unpolarized or randomly polarized, could have no specific or fixed polarization (e.g., the polarization may vary with time), or could have a particular polarization (e.g., the output beam 314 may be linearly polarized, elliptically polarized, or circularly polarized).
In at least some non-limiting embodiments of the present technology, the output beam 314 and the input beam 316 may be substantially coaxial. In other words, the output beam 314 and input beam 316 may at least partially overlap or share a common propagation axis, so that the input beam 316 and the output beam 314 travel along substantially the same optical path (albeit in opposite directions). Nevertheless, in other non-limiting embodiments of the present technology, the output beam 314 and the input beam 316 may not be coaxial, or in other words, may not overlap or share a common propagation axis inside the LiDAR system 300, without departing from the scope of the present technology.
It should be noted that in at least some non-limiting embodiments of the present technology, the light source 302 could be rotatable, such as by 360 degrees or less, about the axis of rotation (not depicted) of the LiDAR system 300 when the LiDAR system 300 is implemented in a rotatable configuration. However, in other embodiments, the light source 302 may be stationary even when the LiDAR system 300 is implemented in a rotatable configuration, without departing from the scope of the present technology.
With continued reference to
However, in accordance with other non-limiting embodiments of the present technology, the beam splitting element 304 may be configured to split the output beam 314 into at least two components of lesser intensity including a scanning beam (not separately depicted) used for scanning the surroundings 250 of the LiDAR system 300, and a reference beam (not separately depicted), which is further directed to the receiving unit 306.
In other words, in these embodiments, the beam splitting element 304 can be said to be configured to divide intensity (optical power) of the output beam 314 between the scanning beam and the reference beam. In some non-limiting embodiments of the present technology, the beam splitting element 304 may be configured to divide the intensity of the output beam 314 between the scanning beam and the reference beam equally. However, in other non-limiting embodiments of the present technology, the beam splitting element 304 may be configured to divide the intensity of the output beam 314 at any predetermined splitting ratio. For example, the beam splitting element 304 may be configured to use up to 80% of the intensity of the output beam 314 for forming the scanning beam, and the remainder of up to 20% of the intensity of the output beam 314—for forming the reference beam. In yet other non-limited embodiments of the present technology, the beam splitting element 304 may be configured to vary the splitting ratio for forming the scanning beam (for example, from 1% to 95% of the intensity of the output beam 314).
It should further be noted that some portion (for example, up to 10%) of the intensity of the output beam 314 may be absorbed by a material of the beam splitting element 304, which depends on a particular configuration thereof.
Depending on the implementation of the LiDAR system 300, the beam splitting element 304 could be provided in a variety of forms, including but not limited to: a glass prism-based beam splitter component, a half-silver mirror-based beam splitter component, a dichroic mirror prism-based beam splitter component, a fiber-optic-based beam splitter component, and the like.
Thus, according to the non-limiting embodiments of the present technology, a non-exhaustive list of adjustable parameters associated with the beam splitting element 304, based on a specific application thereof, may include, for example, an operating wavelength range, which may vary from a finite number of wavelengths to a broader light spectrum (from 1200 to 1600 nm, as an example); an income incidence angle; polarizing/non-polarizing, and the like.
In a specific non-limiting example, the beam splitting element 304 can be implemented as a fiber-optic-based beam splitter component that may be of a type available from OZ Optics Ltd. of 219 Westbrook Rd Ottawa, Ontario K0A 1L0 Canada. It should be expressly understood that the beam splitting element 304 can be implemented in any other suitable equipment.
As is schematically depicted in
Similarly, the input beam 316 follows the plurality of internal beam paths 312 to the receiving unit 306. Specifically, the input beam 316 is directed by the scanner unit 308 into the LiDAR system 300 through the beam splitting element 304, toward the receiving unit 306. In some implementations, the LiDAR system 300 could be arranged with beam paths that direct the input beam 316 directly from the surroundings 250 to the receiving unit 306 (without the input beam 316 passing through the scanner unit 308).
It should be noted that, in various non-limiting embodiments of the present technology, the plurality of internal beam paths 312 may include a variety of optical components. For example, the LiDAR system 300 may include one or more optical components configured to condition, shape, filter, modify, steer, or direct the output beam 314 and/or the input beam 316. For example, the LiDAR system 300 may include one or more lenses, mirrors, filters (e.g., band pass or interference filters), optical fibers, circulators, beam splitters, polarizers, polarizing beam splitters, wave plates (e.g., half-wave or quarter-wave plates), diffractive elements, microelectromechanical (MEM) elements, collimating elements, or holographic elements.
It is contemplated that in at least some non-limiting embodiments of the present technology, the given internal beam path and the other internal beam path from the plurality of internal beam paths 312 may share at least some common optical components, however, this might not be the case in each and every embodiment of the present technology.
Generally speaking, the scanner unit 308 steers the output beam 314 in one or more directions downrange towards the surroundings 250. The scanner unit 308 is communicatively coupled to the controller 310. As such, the controller 310 is configured to control the scanner unit 308 so as to guide the output beam 314 in a desired direction downrange and/or along a predetermined scan pattern. Broadly speaking, in the context of the present specification “scan pattern” may refer to a pattern or path along which the output beam 314 is directed by the scanner unit 308 during operation.
In certain non-limiting embodiments of the present technology, the controller 310 is configured to cause the scanner unit 308 to scan the output beam 314 over a variety of horizontal angular ranges and/or vertical angular ranges; the total angular extent over which the scanner unit 308 scans the output beam 314 is referred to herein as the field of view (FoV). It is contemplated that the particular arrangement, orientation, and/or angular ranges could depend on the particular implementation of the LiDAR system 300. The field of view generally includes a plurality of regions of interest (ROIs), defined as portions of the FoV which may contain, for instance, objects of interest. In some implementations, the scanner unit 308 can be configured to further investigate a selected region of interest (ROI) 325. The ROI 325 of the LiDAR system 300 may refer to an area, a volume, a region, an angular range, and/or portion(s) of the surroundings 250 about which the LiDAR system 300 may be configured to scan and/or can capture data.
It should be noted that a location of the object 320 in the surroundings 250 of the vehicle 220 may be overlapped, encompassed, or enclosed at least partially within the ROI 325 of the LiDAR system 300.
According to certain non-limiting embodiments of the present technology, the scanner unit 308 may be configured to scan the output beam 314 horizontally and/or vertically, and as such, the ROI 325 of the LiDAR system 300 may have a horizontal direction and a vertical direction. For example, the ROI 325 may be defined by 45 degrees in the horizontal direction, and by 45 degrees in the vertical direction. In some implementations, different scanning axes could have different orientations.
In certain embodiments, the scanner unit 308 includes a mirror 309 which is coupled with a galvanometer (not separately depicted) providing control thereto. Accordingly, the controller 310 causes, via the galvanometer, rotation of the mirror about a perpendicular axis associated therewith, thereby scanning the ROI 325 according to the predetermined scan pattern.
In certain non-limiting embodiments of the present technology, the scanner unit 308 may further include a variety of other optical components and/or mechanical-type components for performing the scanning of the output beam 314. For example, the scanner unit 308 may include one or more mirrors, prisms, lenses, MEM components, piezoelectric components, optical fibers, splitters, diffractive elements, collimating elements, and the like. It should be noted that the scanner unit 308 may also include one or more additional actuators (not separately depicted) driving at least some of the other optical components to rotate, tilt, pivot, or move in an angular manner about one or more axes, for example.
The LiDAR system 300 may thus make use of the predetermined scan pattern to generate a point cloud substantially covering the ROI 325 of the LiDAR system 300. As will be described in greater detail herein further below, this point cloud of the LiDAR system 300 may be used to render a multi-dimensional map of objects in the surroundings 250 of the vehicle 220.
As will become apparent from the description provided herein below, in certain non-limiting embodiments of the present technology, a scanning face of the mirror may be configured to associated with a respective scanning frequency.
According to certain non-limiting embodiments of the present technology, the receiving unit 306 is communicatively coupled to the controller 310 and may be implemented in a variety of ways. According to the present technology, the receiving unit 306 includes a photodetector, but could include (but is not limited to) a photoreceiver, optical receiver, optical sensor, detector, optical detector, optical fibers, and the like. As mentioned above, in some non-limiting embodiments of the present technology, the receiving unit 306 may be configured to acquire or detects at least a portion of the input beam 316 and produces an electrical signal that corresponds to the input beam 316. For example, if the input beam 316 includes an optical pulse, the receiving unit 306 may produce an electrical current or voltage pulse that corresponds to the optical pulse detected by the receiving unit 306.
It is contemplated that, in various non-limiting embodiments of the present technology, the receiving unit 306 may be implemented with one or more avalanche photodiodes (APDs), one or more single-photon avalanche diodes (SPADs), one or more PN photodiodes (e.g., a photodiode structure formed by a p-type semiconductor and a n-type semiconductor), one or more PIN photodiodes (e.g., a photodiode structure formed by an undoped intrinsic semiconductor region located between p-type and n-type regions), and the like.
In some non-limiting embodiments, the receiving unit 306 may also include circuitry that performs signal amplification, sampling, filtering, signal conditioning, analog-to-digital conversion, time-to-digital conversion, pulse detection, threshold detection, rising-edge detection, falling-edge detection, and the like. For example, the receiving unit 306 may include electronic components configured to convert a received photocurrent (e.g., a current produced by an APD in response to a received optical signal) into a voltage signal. The receiving unit 306 may also include additional circuitry for producing an analog or digital output signal that corresponds to one or more characteristics (e.g., rising edge, falling edge, amplitude, duration, and the like) of a received optical pulse.
Depending on the implementation, the controller 310 may include one or more processors, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and/or other suitable circuitry. The controller 310 may also include non-transitory computer-readable memory to store instructions executable by the controller 310 as well as data which the controller 310 may produce based on the signals acquired from other internal components of the LiDAR system 300 and/or may provide signals to the other internal components of the LiDAR system 300. The memory can include volatile (e.g., RAM) and/or non-volatile (e.g., flash memory, a hard disk) components. The controller 310 may be configured to generate data during operation and store it in the memory. For example, this data generated by the controller 310 may be indicative of the data points in the point cloud of the LiDAR system 300.
It is contemplated that, in at least some non-limiting embodiments of the present technology, the controller 310 could be implemented in a manner similar to that of implementing the electronic device 210 and/or the computer system 100, without departing from the scope of the present technology. In addition to collecting data from the receiving unit 306, the controller 310 could also be configured to provide control signals to, and potentially receive diagnostics data from, the light source 302 and the scanner unit 308.
As previously stated, the controller 310 is communicatively coupled to the light source 302, the scanner unit 308, and the receiving unit 306. In some non-limiting embodiments of the present technology, the controller 310 may be configured to receive electrical trigger pulses from the light source 302, where each electrical trigger pulse corresponds to the emission of an optical pulse by the light source 302. The controller 310 may further provide instructions, a control signal, and/or a trigger signal to the light source 302 indicating when the light source 302 is to produce optical pulses indicative, for example, of the output beam 314.
Just as an example, the controller 310 may be configured to send an electrical trigger signal that includes electrical pulses, so that the light source 302 emits an optical pulse, representable by the output beam 314, in response to each electrical pulse of the electrical trigger signal. It is also contemplated that the controller 310 may cause the light source 302 to adjust one or more characteristics of output beam 314 produced by the light source 302 such as, but not limited to: frequency, period, duration, pulse energy, peak power, average power, and wavelength of the optical pulses.
By the present technology, the controller 310 is configured to determine a “time-of-flight” value for an optical pulse in order to determine the distance between the LiDAR system 300 and one or more objects in the field of view, as will be described further below. The time of flight is based on timing information associated with (i) a first moment in time when a given optical pulse (for example, of the output beam 314) was emitted by the light source 302, and (ii) a second moment in time when a portion of the given optical pulse (for example, from the input beam 316) was detected or received by the receiving unit 306. In some non-limiting embodiments of the present technology, the first moment may be indicative of a moment in time when the controller 310 emits a respective electrical pulse associated with the given optical pulse; and the second moment in time may be indicative of a moment in time when the controller 310 receives, from the receiving unit 306, an electrical signal generated in response to receiving the portion of the given optical pulse from the input beam 316.
In other non-limiting embodiments of the present technology, where the beam splitting element 304 is configured to split the output beam 314 into the scanning beam (not depicted) and the reference beam (not depicted), the first moment in time may be a moment in time of receiving, from the receiving unit 306, a first electrical signal generated in response to receiving a portion of the reference beam. Accordingly, in these embodiments, the second moment in time may be determined as the moment in time of receiving, by the controller 310 from the receiving unit 306, a second electrical signal generated in response to receiving an other portion of the given optical pulse from the input beam 316.
By the present technology, the controller 310 is configured to determine, based on the first moment in time and the second moment in time, a time-of-flight value and/or a phase modulation value for the emitted pulse of the output beam 314. The time-of-light value T, in a sense, a “round-trip” time for the emitted pulse to travel from the LiDAR system 300 to the object 320 and back to the LiDAR system 300. The controller 310 is thus broadly configured to determine the distance 318 in accordance with the following equation:
wherein D is the distance 318, T is the time-of-flight value, and c is the speed of light (approximately 3.0×108 m/s).
As previously alluded to, the LiDAR system 300 may be used to determine the distance 318 to one or more other potential objects located in the surroundings 250. By scanning the output beam 314 across the ROI 325 of the LiDAR system 300 in accordance with the predetermined scan pattern, the controller 310 is configured to map distances (similar to the distance 318) to respective data points within the ROI 325 of the LiDAR system 300. As a result, the controller 310 is generally configured to render these data points captured in succession (e.g., the point cloud) in a form of a multi-dimensional map. In some implementations, data related to the determined time of flight and/or distances to objects could be rendered in different informational formats.
As an example, this multi-dimensional map may be used by the electronic device 210 for detecting, or otherwise identifying, objects or determining a shape or distance of potential objects within the ROI 325 of the LiDAR system 300. It is contemplated that the LiDAR system 300 may be configured to repeatedly/iteratively capture and/or generate point clouds at any suitable rate for a given application.
Turning now to
One such example of a scanner unit of the prior art having a planar scanning face is an oscillating mirror. Developers noted that such scanner units with planar reflecting surfaces of the prior art (
Therefore, developers sought to compensate for the data point distribution caused by the variable speed of movement of different parts of the scanning face during oscillation. In this respect, developers developed the scanner unit 308 having the non-planar scanning face 350 (
As can be seen in the magnified view of the scanning face 350 of
In certain embodiments, at least some of the reflective surface segments 370 are linear and have a given angle 378 relative to a reference 380. The given angle 378 is also referred to herein as a “reference angle”. By reference is meant a reference plane(s) or a reference direction. In certain embodiments, at least some of the reflective surface segments 370 are angled with respect to one another. By angled is meant that the reflective surface segments 370 are not on the same plane. An angle between two given reflective surface segments 370 may range between about 0.1° and about 180°, or more preferably between about 0° and between about 90°. By angled is also meant, in certain embodiments, that the reference angle 378 of at least some of the reflective surface segments 370 is different to the reference angle 378 of some other reflective surface segments 370. In other words, a topology of the scanning face 350 can be said to be non-planar by virtue of the different reference angles 378 of different reflective surface segments 370.
The number of reflective surface segments 370 of the scanning face 350 is not limited. In certain embodiments, the number of reflective surface segments 370 is large enough to smooth a resulting curvature of the scanning face 350, which can be considered as an envelope curve. The number of reflective surface segments 370, their size, their shape and their relative reference angles 378 are determined according to the scanning pattern and the data point 352 distribution of the scanning pattern requiring modulation. In other words, a configuration of the reflective surface segments 370 of the non-linear scanning face 350 is determined based on one or more of a speed of oscillation of the scanner unit 308 and dimensions of the overall scanning face 350. At least some of the reflective surface segments 370 are configured to modulate the distribution of the data points 352 of the FOV 356 through modulating a propagating angle 382 of the output beam 314 (also referred to as “angle of reflection 382”) into the FOV 356. It will be appreciated, that in certain embodiments, only a portion of the data points 352 may require re-distribution in order to obtain a substantially homogenous distribution of data points 352 throughout the FOV 356. In these cases, only those reflective surface segments 370 associated with the data points 352 requiring re-distribution may have the reference angle 378 different to that of a linear surface. In other words, the scanning face 350 may comprise at least some reflective surface segments 370 which are configured to re-distribute a position of associated data points in order to obtain a homogenous distribution of the data points 352.
The manner of determination of the configuration (e.g. position 376 and reference angle 378) of the reflective surface segments 370 of the embodiments of the scanning face 350 are set out hereinbelow.
Without being limited to any theory, it is noted that the propagating angle of the propagating beam 354 on a reflecting surface of a mirror is proportional to the double slope angle of the mirror. By slope angle is meant an angle relative to a reference plane, such as the reference 380. If the mirror is planar, a displacement angle of the mirror surface (i.e. oscillation angle) is equal to the displacement angle of the mirror. (φpp(displacement angle of the planar mirror)=φd.
However, this is not true when the mirror is curvilinear. If the mirror is curved, the displacement angle of the mirror surface is defined by the displacement angle of the mirror plus a curvature of the mirror: φpk=φd+φc; where φpk−displacement angle of the curved mirror. Consequently, the shape of the scanning face can influence the pattern of scanning.
A relationship between curvature, incident angle and reflection angle can be generally defined as: γcurved=2(β+f(β)), in which γcurved is the angle of reflection, and β is the curvature of the scanning face. Therefore, it can be said that the angle of reflection on a curved scanning face is proportional to two times the curvature of the scanning face.
Therefore, for an uneven data point distribution (also referred to herein as uneven scanning pattern), such as that illustrated in
In this way, the position 376 and the reference angle 378 of the reflective surface segments 370 are determined according a default distribution of the data points 352 based on the movement of the scanning face 350 and its size, a desired distribution of the data points 352, and the propagating angle 382 of the given propagating beam 354 necessary to obtain the desired distribution.
In certain embodiments (as illustrated in
In certain embodiments, and with reference to
In certain embodiments, the scanner unit 308 may include both the prism 388 and the oscillating mirror 384.
In certain embodiments of any of the above embodied versions of the scanner unit, 308 at least two of the reflective surface segments 370 may be made of different materials having different optical properties, or include one or more layers of different materials. For example, the different materials may adapt an optical property of the output beam 314, such as its polarization, wavelength, frequency etc. As a consequence, the resultant propagating beams 354 may have different optical properties.
It will be appreciated that in certain embodiments, the output beam 314 is not positioned directionally relative to the scanner unit 308. In other words, the output beam 314 is caused to be incident on the given reflective surface segment 370 through movement of the controller 310 according to a predetermined sequence.
In certain embodiments, one or more of the reflective surface segments 370 may be individually moveable to adjust the associated reference angle 378. In this respect, in certain embodiments one or more of the reflective surface segments 370 have a configuration which can be modulated such as a shape, an angle etc. The one or more of the reflective surface segments may be made of a flexible material with a coating. The one or more of the reflective surface segments may comprise a number of different sets of segments, and can be used to adjust the FOV. The modulation of the individual reflective surface segments 370 or a set of the reflective surface segments 370 may be performed using a mechanical adjustment system or by a piezoelectric system.
The controller 310 is configured to execute a method 1000 for operating a LiDAR system, such as the LiDAR system 300, in a manner which can generate a scanning pattern with a substantially homogenous distribution of data points 352, in certain embodiments.
With reference now to
STEP 1010: Causing a Radiation Source to Emit Output Beams Along an Internal Emission Pathway of a LIDAR System
The method 1000 comprises causing a radiation source to emit output beams along an internal emission pathway of a LIDAR system. The LIDAR system may comprise an embodiment of the LiDAR system 300 and including the light source 302 and the output beam 314.
STEP 1020: Causing a Scanner of the LIDAR System to Direct the Output Beams onto a Field of View of the LIDAR System as Propagating Beams with a Propagating Angle Such that a Distribution of Data Points in a Scanning Pattern Across the Field of View is Modulated.
The scanner of Step 1020 may comprise the scanner unit 308 of the present technology and comprising the plurality of reflective surface segments 370, each reflective surface segment 370 having: the given position 376 on the scanning face 350, and the given angle 378 relative to a reference 380 for reflecting the output beams 314 as the propagating beam 354 with the given propagating angle 382.
In certain embodiments, the given position 376 and the given angle 378 of at least some of the plurality of reflective surface segments 370 is configured to generate a homogenous density of the data points 352 throughout the outer and central portions 360,362 of the scanning pattern.
In certain embodiments, the controller 310 is configured to cause the output beams 314 to be incident on the plurality of reflective surface segments 370 according to a predetermined sequence.
The method 1020 hence terminates.
From another aspect, there is provided a method for determining a modulated configuration of a scanner unit 308 for providing a homogenous scanning pattern. The method comprises a controller, such as the controller 310, determining a preliminary scanning pattern generated by a preliminary scanning face of the scanner unit; if the preliminary scanning pattern is not homogenous, the method further comprises the controller determining a desired modulation of a given propagating angle 382 of a given propagating beam to create the homogenous scanning pattern; determining which portion of the preliminary scanning face of the scanner unit the output beam will be incident to be reflected as the given propagating beam; and adjusting an angle of the identified portion of the preliminary scanning face to achieve the desired modulation of the given propagating beam.
Thus, certain non-limiting embodiments of the LiDAR system 300 allow for providing a homogenous scanning pattern in the FOV or ROI which can improve detection of objects in the surroundings of the vehicle 220. More specifically, the detection of objects will be as accurate throughout the FOV or ROI. “Blind spots” can be avoided.
Accordingly, these non-limiting embodiments of the LiDAR system 300 allow for registering more reliable data of one or more objects throughout the surroundings 250, thereby providing, for example, for (1) generating a more accurate multi-dimensional map of the objects; and (2) more effective controlling operation (such as trajectory-planning) for the vehicle 220 in terms of avoiding collisions with the objects in the surroundings 250, for example.
Modifications and improvements to the above-described implementations of the present technology may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present technology is therefore intended to be limited solely by the scope of the appended claims.
While the above-described implementations have been described and shown with reference to particular steps performed in a particular order, it will be understood that these steps may be combined, sub-divided, or re-ordered without departing from the teachings of the present technology. Accordingly, the order and grouping of the steps is not a limitation of the present technology.
CLAUSE 1. A LIDAR system for detecting objects in a surrounding environment of an autonomous vehicle, the LIDAR system comprising: a radiation source configured to emit output beams along an internal emission pathway; a scanner, positionable along the internal emission pathway and configured to direct the output beams onto a field of view of the surrounding environment as a plurality of data points in a scanning pattern, wherein the scanner comprises: a scanning face having a non-planar profile and comprising a plurality of reflective surface segments, each reflective surface segment having: a given position on the scanning face, and a given angle relative to a reference for reflecting the output beams as a propagating beam with a given propagating angle; wherein the given position and the given angle of each reflective surface segment is configured to modulate a distribution of the data points in the scanning pattern across the field of view.
CLAUSE 2. The LIDAR system of clause 1, wherein the given position and the given angle of at least some of the plurality of reflective surface segments is configured to generate a homogenous distribution of the data points throughout at least a portion of the scanning pattern.
CLAUSE 3. The LIDAR system of clause 2, wherein the given position and the given angle of at least some of the plurality of reflective surface segments is configured to generate a homogenous density of the data points throughout an outer portion and a central portion of the scanning pattern.
CLAUSE 4. The LIDAR system of any one of clauses 1-3, wherein the given position and the given angle of at least some of the plurality of reflective surface segments is configured to compensate for a difference in scanning frequency at an end of the scanning face compared to at a center of the scanning face in order to modulate a distribution of the data points.
CLAUSE 5. The LIDAR system of any one of clauses 1-4, wherein at least one reflective surface segment of the plurality of reflecting surface segments is linear.
CLAUSE 6. The LIDAR system of any one of clauses 1-4, wherein at least one reflective surface segment of the plurality of reflecting surface segments is curvilinear.
CLAUSE 7. The LIDAR system of any one of clauses 1-6, wherein the plurality of reflective surface segments are configured to render the scanning face with a convex configuration.
CLAUSE 8. The LIDAR system of any one of clauses 1-6, wherein the plurality of reflective surface segments are configured to render the scanning face with a concave configuration.
CLAUSE 9. The LIDAR system of any one of clauses 1-8, wherein the scanner is an oscillating galvo mirror.
CLAUSE 10. The LIDAR system of any one of clauses 1-8, wherein the scanner is a rotating prism and the scanning face is a face of the rotating prism.
CLAUSE 11. The LIDAR system of any one of clauses 1-8, wherein the scanner comprises a rotating prism and a mirror, the scanning face comprising at least one face of the rotating prism and at least one face of the mirror.
CLAUSE 12. The LIDAR system of any one of clauses 1-11, wherein at least two of the plurality of reflective surface segments are angularly off-set from one another.
CLAUSE 13. The LIDAR system of any one of clauses 1-12, wherein at least two of the plurality of the reflective surface segments are made of different materials to impart different optical properties on the respective propagating beams.
CLAUSE 14. The LIDAR system of any one of clauses 1-13, wherein the plurality of the reflective surface segments are configured to form a linear rounded surface.
CLAUSE 15. The LIDAR system of any one of clauses 1-14, further comprising a controller communicatively coupled to the radiation source and the scanner, the controller being configured to cause a given output beam to be incident on a given reflective surface segment.
CLAUSE 16. The LIDAR system of clause 15, wherein the controller is configured to move the scanner for selective contact of the output beams with a given reflective surface segment.
CLAUSE 17. The LIDAR system of clause 15 or clause 16, wherein the controller is configured to move the output beams for selective contact of the output beams with a given segment reflective surface.
CLAUSE 18. The LIDAR system of any one of clauses 1-17, further comprising a receiver for receiving reflected propagating beams from the field of view.
CLAUSE 19. A method for detecting objects in a surrounding environment of an autonomous vehicle, the method executable by a controller which is communicatively coupled to a radiation source and a scanner of a LIDAR system, the method comprising: causing the radiation source to emit output beams along an internal emission pathway of the LIDAR system; causing the scanner to direct the output beams onto a field of view (FOV) within the surrounding environment, the scanner comprising: a scanning face having a non-planar profile and comprising a plurality of reflective surface segments having: a given position on the scanning face, and a given angle relative to a reference for reflecting the output beams as a propagating beam with a given propagating angle; wherein the given position and the given angle of at least some of the plurality of reflective surface segments is configured to modulate the propagating angle of the propagating beam to modulate a distribution of the data points in the scanning pattern across the field of view.
CLAUSE 20. The method of clause 1, further comprising a controller communicatively coupled to the radiation source and the scanner, the controller being configured to cause a given output beam to be incident on a given reflective surface segment.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020133316 | Oct 2020 | RU | national |
