Patent Description:
Frequency Modulated Continuous Wave (FMCW) LIDAR directly measures range and velocity of an object by directing a frequency modulated, collimated light beam at a target. Both range and velocity information of the target can be derived from FMCW LIDAR signals. Designs and techniques to increase the accuracy of LIDAR signals are desirable.

The automobile industry is currently developing autonomous features for controlling vehicles under certain circumstances. According to SAE International standard J3016, there are <NUM> levels of autonomy ranging from Level <NUM> (no autonomy) up to Level <NUM> (vehicle capable of operation without operator input in all conditions). A vehicle with autonomous features utilizes sensors to sense the environment that the vehicle navigates through. Acquiring and processing data from the sensors allows the vehicle to navigate through its environment. Autonomous vehicles may include one or more FMCW LIDAR devices for sensing its environment. <CIT> discloses a vehicle, Lidar system and method of detecting an object. The Lidar system of <CIT> includes an optical phase array and a mirror, wherein the optical phase array directs a transmitted light beam generated by a laser along a first direction within a first plane. The mirror of <CIT> receives the transmitted light beam from the optical phase array and directs the transmitted light beam along a second direction within a second plane. <CIT> discloses an apparatus for optical communication or sensing, comprising: a quarter wave plate (QWP) disposed on a silicon photonic chip to convert a first linearly polarized mode optical beam from a laser disposed on the silicon photonic chip, into a combination of quarter-wave phase-delayed orthogonal polarization modes optical beam, and to convert or contribute in converting a reflection of the combined polarized modes optical beam into a second linearly polarized mode optical beam, within the silicon photonic chip. <CIT> discloses various forms of optical circulator. The optical circulators of <CIT> act on polarisation of the light to direct light between its ports. <CIT> also relates to systems and methods for facilitating estimation of a spatial profile of an environment based on a light detection and ranging (LiDAR) based technique. <CIT> discloses a light detection and ranging (LIDAR) system comprising: a transceiver configured to transmit a transmit signal from a laser source in a transmission mode and to receive a return signal reflected by an object in a receive mode; and one or more optics configured to spatially separate the transmission mode and the receive mode by optically changing a distance between the transmit signal and the return signal.

According to a first aspect of the present invention, there is provided a light detection and ranging (LIDAR) system as set out in independent claim <NUM>. According to a second aspect of the present invention, there is provided an autonomous vehicle control system as set out in claim <NUM>. According to a third aspect of the present invention, there is provided an autonomous vehicle as set out in claim <NUM>. Other embodiments are described in the dependent claims.

Non-limiting and non-exhaustive implementations of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

Implementations of beam displacement for LIDAR are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of the implementations. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

Reference throughout this specification to "one implementation" or "an implementation" means that a particular feature, structure, or characteristic described in connection with the implementation is included in at least one implementation of the present invention. Thus, the appearances of the phrases "in one implementation" or "in an implementation" in various places throughout this specification are not necessarily all referring to the same implementation. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more implementations.

Throughout this specification, several terms of art are used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise. For the purposes of this disclosure, the term "autonomous vehicle" includes vehicles with autonomous features at any level of autonomy of the SAE International standard J3016.

In aspects of this disclosure, visible light may be defined as having a wavelength range of approximately <NUM> - <NUM>. Non-visible light may be defined as light having wavelengths that are outside the visible light range, such as ultraviolet light and infrared light. Infrared light having a wavelength range of approximately <NUM> - <NUM> includes near-infrared light. In aspects of this disclosure, near-infrared light may be defined as having a wavelength range of approximately <NUM> - <NUM>.

In aspects of this disclosure, the term "transparent" may be defined as having greater than <NUM>% transmission of light. In some aspects, the term "transparent" may be defined as a material having greater than <NUM>% transmission of visible light.

Frequency Modulated Continuous Wave (FMCW) LIDAR directly measures range or velocity of an object by directing a frequency modulated, collimated light beam at the object. The light that is reflected from the object is combined with a tapped version of the beam. The frequency of the resulting beat tone is proportional to the distance of the object from the LIDAR system once corrected for the doppler shift that requires a second measurement. The two measurements, which may or may not be performed at the same time, provide both range and velocity information.

FMCW LIDAR can take advantage of integrated photonics for improved manufacturability and performance. Integrated photonic systems typically manipulate single optical modes using micron-scale waveguiding devices.

A LIDAR system may include of one or more continuously moving mirrors which steer the outgoing light towards a target at range and reflect the received light from that target into a receiver. Due to the transit time for light moving from the LIDAR to a target and back, the continuous motion of the mirror causes the received light to move away from the few-micron-sized transceiver. This "beam walk-off" effect can lead to a reduction in system performance.

FMCW LIDAR operation typically involves splitting the optical source power into a "local oscillator" (LO) component and a "signal" component. A simple integrated implementation of FMCW LIDAR involves co-locating the transmitter and receiver. This, however, may lead to additional loss as the receive optical power must pass back through the LO/signal splitter. In order to increase performance, it is desirable to separate the transmitter and receiver such that this splitter does not add additional loss to the optical system. In these implementations, the transmitter and receiver are non-coaxial and are spaced apart from each other.

In implementations of the disclosure, a LIDAR system includes a non-coaxial transmitter and receiving pixel, a rotating mirror, and a beam displacement apparatus configured to introduce a displacement to a returning beam to compensate for a spacing between the transmitter and the receiving pixel. The beam displacement apparatus may also be configured to compensate for a reflection angle difference between the transmit beam and the returning beam reflecting off of the rotating mirror. The beam displacer apparatus may include a beam displacer element including a birefringent material that introduces the displacement to a particular polarization orientation of the returning beam to direct the returning beam to the receiving pixel. The transmit beam and the returning beam (the transmit beam reflection/scattering off a target) may have a near-infrared wavelength.

In some implementations, the beam displacement apparatus includes a beam rotator that rotates a transmit polarization of the transmit beam (emitted by the transmitter). The beam rotator is a switchable beam rotator (e.g. switchable waveplate), in some implementations. The switchable beam rotator may be driven to a first retardation value (e.g. <NUM> degrees) when the rotating mirror is rotating in a first direction (e.g. clockwise) and driven to a second retardation value (e.g. <NUM> degrees) when the rotating mirror is rotating in a second opposite direction (e.g. counter-clockwise).

In some aspects of the disclosure, an apparatus is described for correcting beam walk-off in LIDAR applications which comprises a hybrid silicon/III-V or hybrid silicon/SiO2 platform. Light may be emitted from the transmitter array with polarization A which passes through a birefringent material. As the light passes through the birefringent material, the beam becomes offset relative to the source as a result of refraction. This light leaves the LIDAR system and reflects off of a diffuse surface at some distance from the system. Light reflected off of a diffuse surface may have its polarization randomized. The light in the polarization orthogonal to the emitted polarization (A) propagates back through the birefringent material, which introduces a different displacement to the beam compared to the emitted light. This beam illuminates an array of coherent pixels located in a silicon chip which receives the light in the polarization orthogonal to the transmitter. The birefringent material and geometry can be selected to choose a particular set of transmit and receive offsets which mitigate beam walk-off in LIDAR systems. The birefringent material and geometry can also be selected to choose a particular set of transmit and receive offsets which implements non-coaxial transmitters and receivers. These and other implementations are described in more detail in connection with <FIG>.

<FIG> illustrates a hybrid silicon/III-V photonics implementation of a solid state FMCW LIDAR system which leverages a beam displacement apparatus <NUM> to implement a non-coaxial transmitter and receiver, in accordance with implementations of the disclosure. <FIG> depicts the top view of optical assembly <NUM> and a side view of the assembly <NUM>. A laser <NUM> provides optical power to the system. Laser <NUM> may be solid state and co-packaged with the silicon chip <NUM> or external to the silicon chip <NUM>. Light <NUM> emitted by laser <NUM> passes through a 1x2 splitter <NUM> which splits X% of the power into the bottom power and Y% of the power into the top port (typically X >> Y). The light coupled leaving the bottom port is routed into a 1xM splitter <NUM> which splits the power evenly between M output waveguides <NUM> in M channel semiconductor optical amplifier (SOA) <NUM>/<NUM> which boosts the optical power in each channel. <FIG> illustrates a plurality of waveguides 136A, 136B, 136C, and 136D (collectively referred to as waveguides <NUM>) when M is integer <NUM>, although M may be any integer number. SOA <NUM>/<NUM> is packaged in a recessed pocket <NUM> of the silicon chip <NUM>. After amplification, the light is coupled out of the edge of SOA <NUM>/<NUM> and reflects off of an angled mirror <NUM>/<NUM> which is formed in the silicon chip <NUM> using, for example, a wet etch. The reflected beam of light (reflected by mirror <NUM>/<NUM>) propagates vertically away from the silicon chip <NUM> as transmit beam <NUM>, propagating through the beam displacement apparatus <NUM>. Mirror <NUM>/<NUM> may be formed on an angled side-wall of recessed pocket <NUM> of silicon chip <NUM> that SOA <NUM>/<NUM> is disposed in. Beam displacement apparatus <NUM> may partially overhang recessed pocket <NUM> of silicon chip <NUM> to receive transmit beam <NUM> reflecting from mirror <NUM> on the angled side-wall.

After propagating through the beam displacement apparatus <NUM>, transmit beam <NUM> propagates into the environment, reflects off of a target, and returns through the beam displacement apparatus <NUM> as returning beam <NUM>. This returning beam <NUM> focuses onto one of the M receiving grating couplers <NUM>/<NUM> which feed an array of M silicon photonic coherent pixels <NUM>. <FIG> illustrates a plurality of grating couplers 114A, 114B, 114C, and 114D (collectively referred to as grating couplers <NUM>), although more or fewer grating couplers <NUM> may be included in the plurality. <FIG> illustrates a plurality of coherent pixels 116A, 116B, 116C, and 116D (collectively referred to as coherent pixels <NUM>), although more or fewer coherent pixels <NUM> may be included in the plurality. The light is routed into each coherent pixel <NUM> where it is combined with the LO optical field.

The LO optical field is obtained from the optical power leaving the top port of splitter <NUM>. In some implementations, this LO optical field may come from a separate laser source which has its own modulation. This light is routed to a second optical amplifier <NUM>, which may be packaged in a similar manner as the SOA <NUM> or external to the chip. This amplified light is routed into a 1xM splitter <NUM>, which evenly distributes the LO field between the M coherent pixels <NUM>.

Each coherent pixel <NUM> mixes the receive optical field (generated by returning beam <NUM> incident onto the respective grating coupler) with the LO field and converts the resulting beat signal to an electrical signal <NUM> which is read out by the FMCW LIDAR system. <FIG> illustrates a plurality of electrical signals 119A, 119B, 119C, and 119D (collectively referred to as electrical signals <NUM>), although more or fewer electrical signals <NUM> may be included in the plurality corresponding to the number M coherent pixels <NUM>.

<FIG> illustrates a hybrid silicon/SiO<NUM> implementation of a solid state FMCW LIDAR system which leverages a beam displacement apparatus <NUM> to implement a non-coaxial transmitter and receiver, in accordance with implementations of the disclosure. <FIG> depicts the top view of optical assembly <NUM> and a side view of the assembly <NUM>. A laser <NUM> provides optical power to the system. Laser <NUM> may be solid state and co-packaged with the silicon chip <NUM> or external to the chip. Light <NUM> emitted by laser <NUM> passes through an optical amplifier <NUM> and then through a 1x2 splitter <NUM> which splits X% of the power into the bottom power and Y% of the power into the top port (typically X >> Y). Both optical amplifier <NUM> and 1x2 splitter <NUM> may be discrete fiber components or solid state components packaged with the silicon chip assembly <NUM>. The light leaving the bottom port is routed into a glass planar lightwave circuit (PLC) <NUM>/<NUM> that includes a 1xM splitter <NUM> and M free-space edge couplers <NUM>. In the illustration of <FIG>, M is integer four and the four free-space edge couplers 209A, 209B, 209C, and 209D are collectively referred to as free-space edge couplers <NUM>.

The light leaving the edge couplers <NUM> of PLC <NUM> reflects off of an angled mirror <NUM>/<NUM> which is formed in the silicon chip using, for example, a wet etch. The reflected beam of light (reflected by mirror <NUM>/<NUM>) propagates vertically away from the silicon chip <NUM> as transmit beam <NUM>, propagating through the beam displacement apparatus <NUM>.

After propagating through the beam displacement apparatus <NUM>, transmit beam <NUM> propagates into the environment, reflects off of a target, and returns through the beam displacement apparatus <NUM> as returning beam <NUM>. This returning beam <NUM> focuses onto one of the M receiving grating couplers <NUM>/<NUM> which feed an array of M silicon photonic coherent pixels <NUM>. <FIG> illustrates a plurality of grating couplers 216A, 216B, 216C, and 216D (collectively referred to as grating couplers <NUM>), although more or fewer grating couplers <NUM> may be included in the plurality. <FIG> illustrates a plurality of coherent pixels 218A, 218B, 218C, and 218D (collectively referred to as coherent pixels <NUM>), although more or fewer coherent pixels <NUM> may be included in the plurality. The light is routed into each coherent pixel <NUM> where it is combined with the LO optical field.

The LO optical field is obtained from the optical power leaving the top port of splitter <NUM>. This light is routed into a silicon photonic 1xM splitter <NUM>, which evenly distributes the LO field between the M coherent pixels <NUM>.

Each coherent pixel <NUM>, mixes the receive optical field (generated by returning beam <NUM> incident onto the respective grating coupler) with the LO field and converts the resulting beat signal to an electrical signal <NUM> which is read out by the FMCW LIDAR system. <FIG> illustrates a plurality of electrical signals 220A, 220B, 220C, and 220D (collectively referred to as electrical signals <NUM>), although more or fewer electrical signals <NUM> may be included in the plurality corresponding to the number M coherent pixels <NUM>.

<FIG> illustrates an example beam displacement apparatus <NUM>, in accordance with implementations of the disclosure. Example beam displacement apparatus may be used as beam displacement apparatus <NUM> or <NUM>, for example. <FIG> illustrates the operation of the beam displacement apparatus for the purpose of implementing no-coaxial transmitters and receivers in FMCW LIDAR as well as for correcting beam walkoff. The operation of beam displacement apparatus <NUM> can be described with respect to transmit path <NUM> and receive path <NUM>.

In transmit path <NUM>, transmitter <NUM> emits transmit beam <NUM> with a particular polarization. Transmit beam <NUM> may be laser light <NUM>/<NUM> generated by laser <NUM>/<NUM>, for example. Transmit beam <NUM> may be infrared light. In some implementations, transmit beam <NUM> is near-infrared light. The depicted location of transmitter <NUM> may be co-located with mirror <NUM> or <NUM>, in some implementations. In the illustration of <FIG>, the transmit polarization of transmit beam <NUM> is <NUM> degrees, however, this initial polarization can be different in different implementations. Transmit beam <NUM> propagates through an optional beam rotator <NUM>, which rotates the transmit polarization, depicted by transmit beam <NUM>, such that it is perpendicular to the optical axis of beam displacer element <NUM>. Optional beam rotator <NUM> can be implemented using a half wave plate or other anisotropic crystal. Beam displacer element <NUM> is disposed between transmitter <NUM> and rotating mirror <NUM>, in <FIG>.

After propagating through beam displacer element <NUM>, transmit beam <NUM> propagates along its original axis and its polarization is unchanged (when compared to the illustration of transmit beam <NUM>). Transmit beam <NUM> enters lens <NUM> which is disposed between beam displacer element <NUM> and rotating mirror <NUM>, in <FIG>. Lens <NUM> may collimate the light and steer it in the desired direction. Lens <NUM> can be implemented using one or more bulk optic lens elements, micro lenses, or thin diffraction gratings. After propagating through lens <NUM>, the light may propagate through an optional waveplate <NUM> disposed between beam displacement element <NUM> and rotating mirror <NUM>. Waveplate <NUM> may be a quarter waveplate configured to shift the polarization axis of incident light by <NUM> degrees. Therefore, incident linearly polarized light may be converted to circularly polarized light by waveplate <NUM>. Likewise, incident circularly polarized light may be converted to linearly polarized light by waveplate <NUM>. Waveplate <NUM> may be made of birefringent materials such as quartz, organic material sheets, or liquid crystal, for example.

In the illustrated implementation, this circularly polarized transmit beam <NUM>, reflects off of rotating mirror <NUM>. Rotating mirror <NUM> may be a continuously rotating mirror that rotates in a particular direction <NUM> (e.g. counter-clockwise direction <NUM> in <FIG>). Rotating mirror <NUM> is configured to direct the transmit beam <NUM> to a target <NUM> in the environment of the LIDAR system or device. Rotating mirror <NUM> is also configured to direct a returning beam to one or more receiving pixels <NUM> in receive path <NUM>.

After striking a target in the environment, the transmit beam returns as returning beam <NUM>, as illustrated in receive path <NUM> of <FIG>. In other words, returning beam <NUM> is transmit beam <NUM> reflecting/scattering off of target <NUM>. Hence, returning beam <NUM> may have the same wavelength as transmit beam <NUM>.

Returning beam <NUM> reflecting/scattering off of target <NUM> propagates back to rotating mirror <NUM>. In the time it took for the light to propagate to target <NUM> and back, the rotating mirror <NUM> has rotated by a small amount in direction <NUM>. As a result, the light of returning beam <NUM> reflects off of rotating mirror <NUM> at a small angle (reflection angle difference <NUM>) relative to the light propagating along the transmit path <NUM>, as shown by returning beam <NUM>. Returning beam <NUM> propagates to beam displacement apparatus <NUM> disposed between receiving pixel <NUM> and rotating mirror <NUM>. Beam displacement apparatus <NUM> is configured to introduce a displacement D2 <NUM> to the returning beam to compensate for a spacing <NUM> between transmitter <NUM> and receiving pixel <NUM>. In <FIG>, beam displacement apparatus <NUM> is also configured to compensate for reflection angle difference <NUM> between the transmit beam <NUM> and the returning beam <NUM> reflecting off of the rotating mirror <NUM>.

This light passes back through quarter waveplate <NUM>. If the target surface maintained the incident polarization, then the returning beam exiting quarter waveplate <NUM> will result in a linear polarization that is perpendicular to the polarization leaving the lens in the transmit direction. If the target randomized the polarization, then the polarization of the returning beam exiting quarter waveplate <NUM> includes both the transmit polarization and the perpendicular polarization. This light passes back through the lens <NUM>. Because of the small change in angle of the mirror (reflection angle difference <NUM>), the returning beam enters lens <NUM> at a small angle, which translates into a small offset, or "beam walkoff"" <NUM> in position of returning beam <NUM> beneath the lens relative to the transmit path. A component of this returning beam's polarization orientation <NUM> will have a non-zero projection onto the optical axis of the beam displacer element <NUM>. This causes the returning beam to be displaced by a fixed displacement amount <NUM> as it propagates through beam displacer element <NUM>. The beam displacer element <NUM> parameters (e.g. material, thickness, optical axis orientation) can be chosen to yield a displacement dimension D2 <NUM> that cancels (or at least adjusts for) the beam walkoff for a target at a specified distance. That is, beam displacement element <NUM> may be configured to compensate for the reflection angle difference <NUM> between the transmit beam <NUM> and the returning beam <NUM> reflection of the mirror. Furthermore, beam displacement element may be configured to yield displacement dimension D2 <NUM> that also compensates for spacing <NUM> between the transmitter <NUM> and receiving pixel <NUM>.

In some implementations, beam displacer element <NUM> includes a birefringent material. In some implementations, the birefringent material may be LiNO<NUM> (Lithium Nitrate). In some implementations, the birefringent material may be YVO<NUM> (Yttrium Orthovanadate). In some implementations, beam displacer element <NUM> does not include birefringent materials. In <FIG>, transmit beam <NUM> has a first polarization orientation as transmit beam <NUM> encounters beam displacement element <NUM> and returning beam <NUM> has a second polarization orientation that is orthogonal to the first polarization orientation of transmit beam <NUM>. The birefringent material of beam displacer element <NUM> may be selected/configured to introduce displacement dimension D2 <NUM> to the second polarization orientation but not the first polarization orientation.

In some implementations, after passing through beam displacer element <NUM>, the returning beam <NUM> now propagates along a similar axis as transmit beam <NUM> (that may be approximately parallel to the axis of transmit beam <NUM>) but with a perpendicular polarization to the transmit polarization of transmit beam <NUM>. In some implementations, the spacing between the axis of returning beam <NUM> and transmit beam <NUM> is approximately the same as spacing <NUM> between the transmitter <NUM> and receiving pixel <NUM>. In some implementations, after passing through beam displacer element <NUM>, the returning beam <NUM> now propagates along the same axis as the transmit beam but with a perpendicular polarization to the transmit polarization of transmit beam <NUM>. Returning beam <NUM> propagates through optional beam rotator <NUM> (that is disposed between transmitter <NUM> and beam displacer element <NUM>) which rotates the polarization by the desired amount to generate returning beam <NUM> having a polarization orientation that is orthogonal to transmit beam <NUM>. Receiving pixel <NUM> is configured to receive returning beam <NUM>.

<FIG> illustrates an example beam displacement apparatus <NUM> that includes a switchable beam rotator <NUM> in accordance with the invention. Switchable beam rotator <NUM> is configured to change the beam displacement direction in response to electrical signal <NUM>. Switchable beam rotator <NUM> may be a switchable half waveplate that includes liquid crystals.

In <FIG>, the behavior of <NUM>-<NUM> and <NUM>-<NUM> are the same or similar to <NUM>-<NUM> except that switchable beam rotator <NUM> can be controlled using an electrical signal <NUM>. Switchable beam rotator <NUM> is driven to a first retardation value (e.g. <NUM> degrees) when the rotating mirror is rotating in a first direction (e.g. direction <NUM>) and to a second retardation value (e.g. <NUM> degrees) when the rotating mirror is rotating in the second opposite direction (e.g. direction <NUM>). Therefore, the polarization orientation of transmit beam <NUM> can be changed by <NUM> degrees dynamically, causing the beam to be displaced in different directions. This is useful in cases where the rotating mirror <NUM> rotates both clockwise (e.g. direction <NUM>) and counterclockwise (e.g. direction <NUM>) during regular operation (which reverses the walkoff direction).

<FIG> illustrates an example autonomous vehicle <NUM> that may include the LIDAR designs of <FIG>, in accordance with aspects of the disclosure. The illustrated autonomous vehicle <NUM> includes an array of sensors configured to capture one or more objects of an external environment of the autonomous vehicle and to generate sensor data related to the captured one or more objects for purposes of controlling the operation of autonomous vehicle <NUM>. <FIG> shows sensor 533A, 533B, 533C, 533D, and 533E. <FIG> illustrates a top view of autonomous vehicle <NUM> including sensors 533F, <NUM>, <NUM>, and <NUM> in addition to sensors 533A, 533B, 533C, 533D, and 533E. Any of sensors 533A, 533B, 533C, 533D, 533E, 533F, <NUM>, <NUM>, and/or 533I may include LIDAR devices that include the designs of <FIG>. <FIG> illustrates a block diagram of an example system <NUM> for autonomous vehicle <NUM>. For example, autonomous vehicle <NUM> may include powertrain <NUM> including prime mover <NUM> powered by energy source <NUM> and capable of providing power to drivetrain <NUM>. Autonomous vehicle <NUM> may further include control system <NUM> that includes direction control <NUM>, powertrain control <NUM>, and brake control <NUM>. Autonomous vehicle <NUM> may be implemented as any number of different vehicles, including vehicles capable of transporting people and/or cargo and capable of traveling in a variety of different environments. It will be appreciated that the aforementioned components <NUM> - <NUM> can vary widely based upon the type of vehicle within which these components are utilized.

The implementations discussed hereinafter, for example, will focus on a wheeled land vehicle such as a car, van, truck, or bus. In such implementations, prime mover <NUM> may include one or more electric motors and/or an internal combustion engine (among others). The energy source may include, for example, a fuel system (e.g., providing gasoline, diesel, hydrogen), a battery system, solar panels or other renewable energy source, and/or a fuel cell system. Drivetrain <NUM> may include wheels and/or tires along with a transmission and/or any other mechanical drive components suitable for converting the output of prime mover <NUM> into vehicular motion, as well as one or more brakes configured to controllably stop or slow the autonomous vehicle <NUM> and direction or steering components suitable for controlling the trajectory of the autonomous vehicle <NUM> (e.g., a rack and pinion steering linkage enabling one or more wheels of autonomous vehicle <NUM> to pivot about a generally vertical axis to vary an angle of the rotational planes of the wheels relative to the longitudinal axis of the vehicle). In some implementations, combinations of powertrains and energy sources may be used (e.g., in the case of electric/gas hybrid vehicles). In some implementations, multiple electric motors (e.g., dedicated to individual wheels or axles) may be used as a prime mover.

Direction control <NUM> may include one or more actuators and/or sensors for controlling and receiving feedback from the direction or steering components to enable the autonomous vehicle <NUM> to follow a desired trajectory. Powertrain control <NUM> may be configured to control the output of powertrain <NUM>, e.g., to control the output power of prime mover <NUM>, to control a gear of a transmission in drivetrain <NUM>, thereby controlling a speed and/or direction of the autonomous vehicle <NUM>. Brake control <NUM> may be configured to control one or more brakes that slow or stop autonomous vehicle <NUM>, e.g., disk or drum brakes coupled to the wheels of the vehicle.

Other vehicle types, including but not limited to off-road vehicles, allterrain or tracked vehicles, or construction equipment will necessarily utilize different powertrains, drivetrains, energy sources, direction controls, powertrain controls, and brake controls, as will be appreciated by those of ordinary skill having the benefit of the instant disclosure. Moreover, in some implementations some of the components can be combined, e.g., where directional control of a vehicle is primarily handled by varying an output of one or more prime movers. Therefore, implementations disclosed herein are not limited to the particular application of the herein-described techniques in an autonomous wheeled land vehicle.

In the illustrated implementation, autonomous control over autonomous vehicle <NUM> is implemented in vehicle control system <NUM>, which may include one or more processors in processing logic <NUM> and one or more memories <NUM>, with processing logic <NUM> configured to execute program code (e.g. instructions <NUM>) stored in memory <NUM>. Processing logic <NUM> may include graphics processing unit(s) (GPUs) and/or central processing unit(s) (CPUs), for example. Vehicle control system <NUM> may be configured to control powertrain <NUM> of autonomous vehicle <NUM> in response to the returning beams (e.g. returning beams <NUM> or <NUM>) or in response to signals <NUM> or <NUM>. Vehicle control system <NUM> may be configured to control powertrain <NUM> of autonomous vehicle <NUM> in response to outputs from a plurality of LIDAR pixels.

Sensors 533A-533I may include various sensors suitable for collecting data from an autonomous vehicle's surrounding environment for use in controlling the operation of the autonomous vehicle. For example, sensors 533A-533I can include RADAR unit <NUM>, LIDAR unit <NUM>, 3D positioning sensor(s) <NUM>, e.g., a satellite navigation system such as GPS, GLONASS, BeiDou, Galileo, or Compass. The LIDAR designs of <FIG> may be included in LIDAR unit <NUM>. LIDAR unit <NUM> may include a plurality of LIDAR sensors that are distributed around autonomous vehicle <NUM>, for example. In some implementations, 3D positioning sensor(s) <NUM> can determine the location of the vehicle on the Earth using satellite signals. Sensors 533A-533I can optionally include one or more ultrasonic sensors, one or more cameras <NUM>, and/or an Inertial Measurement Unit (IMU) <NUM>. In some implementations, camera <NUM> can be a monographic or stereographic camera and can record still and/or video images. Camera <NUM> may include a Complementary Metal-Oxide-Semiconductor (CMOS) image sensor configured to capture images of one or more objects in an external environment of autonomous vehicle <NUM>. IMU <NUM> can include multiple gyroscopes and accelerometers capable of detecting linear and rotational motion of autonomous vehicle <NUM> in three directions. One or more encoders (not illustrated) such as wheel encoders may be used to monitor the rotation of one or more wheels of autonomous vehicle <NUM>.

The outputs of sensors 533A-533I may be provided to control subsystems <NUM>, including, localization subsystem <NUM>, trajectory subsystem <NUM>, perception subsystem <NUM>, and control system interface <NUM>. Localization subsystem <NUM> is configured to determine the location and orientation (also sometimes referred to as the "pose") of autonomous vehicle <NUM> within its surrounding environment, and generally within a particular geographic area. The location of an autonomous vehicle can be compared with the location of an additional vehicle in the same environment as part of generating labeled autonomous vehicle data. Perception subsystem <NUM> may be configured to detect, track, classify, and/or determine objects within the environment surrounding autonomous vehicle <NUM>. Trajectory subsystem <NUM> is configured to generate a trajectory for autonomous vehicle <NUM> over a particular timeframe given a desired destination as well as the static and moving objects within the environment. A machine learning model in accordance with several implementations can be utilized in generating a vehicle trajectory. Control system interface <NUM> is configured to communicate with control system <NUM> in order to implement the trajectory of the autonomous vehicle <NUM>. In some implementations, a machine learning model can be utilized to control an autonomous vehicle to implement the planned trajectory.

It will be appreciated that the collection of components illustrated in <FIG> for vehicle control system <NUM> is merely exemplary in nature. Individual sensors may be omitted in some implementations. In some implementations, different types of sensors illustrated in <FIG> may be used for redundancy and/or for covering different regions in an environment surrounding an autonomous vehicle. In some implementations, different types and/or combinations of control subsystems may be used. Further, while subsystems <NUM> - <NUM> are illustrated as being separate from processing logic <NUM> and memory <NUM>, it will be appreciated that in some implementations, some or all of the functionality of subsystems <NUM> - <NUM> may be implemented with program code such as instructions <NUM> resident in memory <NUM> and executed by processing logic <NUM>, and that these subsystems <NUM> - <NUM> may in some instances be implemented using the same processor(s) and/or memory. Subsystems in some implementations may be implemented at least in part using various dedicated circuit logic, various processors, various field programmable gate arrays ("FPGA"), various application-specific integrated circuits ("ASIC"), various real time controllers, and the like, as noted above, multiple subsystems may utilize circuitry, processors, sensors, and/or other components. Further, the various components in vehicle control system <NUM> may be networked in various manners.

In some implementations, autonomous vehicle <NUM> may also include a secondary vehicle control system (not illustrated), which may be used as a redundant or backup control system for autonomous vehicle <NUM>. In some implementations, the secondary vehicle control system may be capable of operating autonomous vehicle <NUM> in response to a particular event. The secondary vehicle control system may only have limited functionality in response to the particular event detected in primary vehicle control system <NUM>. In still other implementations, the secondary vehicle control system may be omitted.

In some implementations, different architectures, including various combinations of software, hardware, circuit logic, sensors, and networks may be used to implement the various components illustrated in <FIG>. Each processor may be implemented, for example, as a microprocessor and each memory may represent the random access memory ("RAM") devices comprising a main storage, as well as any supplemental levels of memory, e.g., cache memories, non-volatile or backup memories (e.g., programmable or flash memories), or read- only memories. In addition, each memory may be considered to include memory storage physically located elsewhere in autonomous vehicle <NUM>, e.g., any cache memory in a processor, as well as any storage capacity used as a virtual memory, e.g., as stored on a mass storage device or another computer controller. Processing logic <NUM> illustrated in <FIG>, or entirely separate processing logic, may be used to implement additional functionality in autonomous vehicle <NUM> outside of the purposes of autonomous control, e.g., to control entertainment systems, to operate doors, lights, or convenience features.

In addition, for additional storage, autonomous vehicle <NUM> may also include one or more mass storage devices, e.g., a removable disk drive, a hard disk drive, a direct access storage device ("DASD"), an optical drive (e.g., a CD drive, a DVD drive), a solid state storage drive ("SSD"), network attached storage, a storage area network, and/or a tape drive, among others. Furthermore, autonomous vehicle <NUM> may include a user interface <NUM> to enable autonomous vehicle <NUM> to receive a number of inputs from a passenger and generate outputs for the passenger, e.g., one or more displays, touchscreens, voice and/or gesture interfaces, buttons and other tactile controls. In some implementations, input from the passenger may be received through another computer or electronic device, e.g., through an app on a mobile device or through a web interface.

In some implementations, autonomous vehicle <NUM> may include one or more network interfaces, e.g., network interface <NUM>, suitable for communicating with one or more networks <NUM> (e.g., a Local Area Network ("LAN"), a wide area network ("WAN"), a wireless network, and/or the Internet, among others) to permit the communication of information with other computers and electronic devices, including, for example, a central service, such as a cloud service, from which autonomous vehicle <NUM> receives environmental and other data for use in autonomous control thereof. In some implementations, data collected by one or more sensors 533A-533I can be uploaded to computing system <NUM> through network <NUM> for additional processing. In such implementations, a time stamp can be associated with each instance of vehicle data prior to uploading.

Processing logic <NUM> illustrated in <FIG>, as well as various additional controllers and subsystems disclosed herein, generally operates under the control of an operating system and executes or otherwise relies upon various computer software applications, components, programs, objects, modules, or data structures, as may be described in greater detail below. Moreover, various applications, components, programs, objects, or modules may also execute on one or more processors in another computer coupled to autonomous vehicle <NUM> through network <NUM>, e.g., in a distributed, cloudbased, or client-server computing environment, whereby the processing required to implement the functions of a computer program may be allocated to multiple computers and/or services over a network.

Routines executed to implement the various implementations described herein, whether implemented as part of an operating system or a specific application, component, program, object, module or sequence of instructions, or even a subset thereof, will be referred to herein as "program code. " Program code typically comprises one or more instructions that are resident at various times in various memory and storage devices, and that, when read and executed by one or more processors, perform the steps necessary to execute steps or elements embodying the various aspects of the invention. Moreover, while implementations have and hereinafter may be described in the context of fully functioning computers and systems, it will be appreciated that the various implementations described herein are capable of being distributed as a program product in a variety of forms, and that implementations can be implemented regardless of the particular type of computer readable media used to actually carry out the distribution. Examples of computer readable media include tangible, non-transitory media such as volatile and non-volatile memory devices, floppy and other removable disks, solid state drives, hard disk drives, magnetic tape, and optical disks (e.g., CD-ROMs, DVDs) among others.

In addition, various program code described hereinafter may be identified based upon the application within which it is implemented in a specific implementation. However, it should be appreciated that any particular program nomenclature that follows is used merely for convenience, and thus the invention should not be limited to use solely in any specific application identified and/or implied by such nomenclature. Furthermore, given the typically endless number of manners in which computer programs may be organized into routines, procedures, methods, modules, objects, and the like, as well as the various manners in which program functionality may be allocated among various software layers that are resident within a typical computer (e.g., operating systems, libraries, API's, applications, applets), it should be appreciated that the invention is not limited to the specific organization and allocation of program functionality described herein.

Those skilled in the art, having the benefit of the present disclosure, will recognize that the exemplary environment illustrated in <FIG> is not intended to limit implementations disclosed herein. Indeed, those skilled in the art will recognize that other alternative hardware and/or software environments may be used without departing from the scope of implementations disclosed herein.

The term "processing logic" (e.g. processing logic <NUM>) in this disclosure may include one or more processors, microprocessors, multi-core processors, Application-specific integrated circuits (ASIC), and/or Field Programmable Gate Arrays (FPGAs) to execute operations disclosed herein. In some embodiments, memories (not illustrated) are integrated into the processing logic to store instructions to execute operations and/or store data. Processing logic may also include analog or digital circuitry to perform the operations in accordance with embodiments of the disclosure.

A "memory" or "memories" described in this disclosure may include one or more volatile or non-volatile memory architectures. The "memory" or "memories" may be removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data. Example memory technologies may include RAM, ROM, EEPROM, flash memory, CD-ROM, digital versatile disks (DVD), high-definition multimedia/data storage disks, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information for access by a computing device.

A network may include any network or network system such as, but not limited to, the following: a peer-to-peer network; a Local Area Network (LAN); a Wide Area Network (WAN); a public network, such as the Internet; a private network; a cellular network; a wireless network; a wired network; a wireless and wired combination network; and a satellite network.

Communication channels may include or be routed through one or more wired or wireless communication utilizing IEEE <NUM> protocols, SPI (Serial Peripheral Interface), I<NUM>C (Inter-Integrated Circuit), USB (Universal Serial Port), CAN (Controller Area Network), cellular data protocols (e.g. <NUM>, <NUM>, LTE, <NUM>), optical communication networks, Internet Service Providers (ISPs), a peer-to-peer network, a Local Area Network (LAN), a Wide Area Network (WAN), a public network (e.g. "the Internet"), a private network, a satellite network, or otherwise.

A computing device may include a desktop computer, a laptop computer, a tablet, a phablet, a smartphone, a feature phone, a server computer, or otherwise. A server computer may be located remotely in a data center or be stored locally.

A tangible non-transitory machine-readable storage medium includes any mechanism that provides (i.e., stores) information in a form accessible by a machine (e.g., a computer, network device, personal digital assistant, manufacturing tool, any device with a set of one or more processors, etc.). For example, a machine-readable storage medium includes recordable/non-recordable media (e.g., read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.).

Claim 1:
A light detection and ranging (LIDAR) system comprising:
a transmitter (<NUM>) configured to emit a transmit beam (<NUM>; <NUM>; <NUM>);
a receiving pixel (116A-D; <NUM>; <NUM>) configured to receive a returning beam (<NUM>; <NUM>; <NUM>);
a rotating mirror (<NUM>; <NUM>) configured to direct the transmit beam to a target (<NUM>; <NUM>) and direct the returning beam to the receiving pixel, wherein the rotating mirror is configured to rotate in a first direction (<NUM>; <NUM>) and a second opposite direction (<NUM>) during regular operation; and
a beam displacement apparatus (<NUM>; <NUM>; <NUM>; <NUM>) disposed between the receiving pixel and the rotating mirror, wherein the beam displacement apparatus is configured to introduce a displacement (<NUM>) to the returning beam to compensate for a spacing (<NUM>) between the transmitter (<NUM>) and the receiving pixel (<NUM>), and wherein the beam displacement apparatus includes a switchable beam rotator (<NUM>) that is driven to a first retardation value when the rotating mirror is rotating in the first direction and driven to a second retardation value when the rotating mirror is rotating in the second opposite direction.