Patent Application
20230213618
The present disclosure relates to light detection and ranging (LIDAR) based three-dimensional (3-D) point cloud measuring systems.
LIDAR systems generally use beams of light to measure distance (“range”) to an object. Each light beam may include one or more pulses of light. A beam of light emitted from a light source of a LIDAR system interacts with a distal object. A portion of the light reflects from the object and returns to a detector of the LIDAR system. In some cases, the range to the object is estimated based on the time elapsed between emission of the beam of light and detection of the returned beam of light. The time it takes for a beam of laser light to travel to an object and return to a detector mounted near the emitter can be measured. The distance to the object can be derived from the time measurement with high accuracy. In other cases, the range to the object may be determined based on the wavelength (or frequency) of the return beam(s) of light reflected by the object. In some examples, the beams of light are generated by a laser emitter. The light beams may be focused through a lens or lens assembly.
Some LIDAR systems use a single laser emitter/detector combination combined with a rotating mirror to effectively scan across a plane. Distance measurements performed by such a system are effectively two-dimensional (2-D) (i.e., planar), and the captured distance points can be rendered as a 2-D (i.e. single plane) point cloud. In some examples, rotating mirrors are rotated at very fast speeds (e.g., thousands of revolutions per minute).
In many operational scenarios, a 3-D point cloud is preferred. A number of schemes have been used to interrogate the surrounding environment in three dimensions. In some examples, a 2-D instrument is actuated up and down and/or back and forth, often on a gimbal. This is commonly known within the art as “winking” or “nodding” the sensor. Thus, a single beam LIDAR unit can be used to capture an entire 3-D array of distance points, albeit one point at a time. In a related example, a prism is used to “divide” the laser beam into multiple layers, each having a slightly different vertical angle. This simulates the nodding effect described above, but without mechanical actuation of the sensor itself.
In all the above examples, the light path of a single laser emitter/detector combination is altered to achieve a broader field of view than a single sensor. The number of pixels such devices can generate per unit time is generally limited due to limitations on the pulse repetition rate of a single laser. Any alteration of the beam path, whether it is by mirror, prism, or mechanical actuation of the device that achieves a larger coverage area generally comes at a cost of decreased point cloud density.
As noted above, 3-D point cloud systems exist in several configurations. However, in many applications it is preferable to scan over a broad field of view. For example, in an autonomous vehicle application, it is generally preferable for the vertical field of view to extend down as close as possible to see the ground in front of the vehicle. In addition, it is generally preferable for the vertical field of view to extend above the horizon, in the event the car enters a dip in the road. In addition, it is generally preferable to minimize the delay between the actions happening in the real world and the imaging of those actions. In some examples, it is desirable to provide a complete image update at least five times per second. To address these requirements, a 3-D LIDAR system has been developed that includes an array of multiple laser emitters and detectors. This system is described in U.S. Pat. No. 7,969,558 issued on Jun. 28, 2011, the subject matter of which is incorporated by reference herein in its entirety.
In many applications, a sequence of beams is emitted. The direction of each beam is sequentially varied in rapid succession. In these examples, a distance measurement associated with each individual beam can be considered a pixel, and a collection of pixels captured in rapid succession (e.g., “point cloud”) can be rendered as an image or analyzed for other reasons (e.g., detecting obstacles). In some examples, viewing software is used to render the resulting point clouds as images that appear 3-D to a user. Different schemes can be used to depict the distance measurements as 3-D images that appear as if they were captured by a live action camera.
Improvements in the opto-mechanical design of LIDAR systems are desired, while maintaining high levels of imaging resolution and range.
The foregoing examples of the related art and limitations therewith are intended to be illustrative and not exclusive, and are not admitted to be “prior art.” Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.
LIDAR sensors having linear focal planes, and methods of manufacturing and operating such LIDAR sensors, are described herein.
At least one aspect of the present disclosure is directed to a light detection and ranging (LIDAR) device. The LIDAR device includes a plurality of laser sources configured to provide a plurality of transmit beams, each laser source of the plurality of laser sources being positioned with a respective offset of a first plurality of offsets relative to a reference line, a plurality of transmit/receive (T/R) interfaces configured to pass the plurality of transmit beams and reflect received light towards a plurality of detectors, each T/R interface of the plurality of T/R interfaces being positioned with a respective offset of a second plurality of offsets relative to the reference line, and a plurality of lenses positioned between the plurality of laser sources and the plurality of T/R interfaces, each lens of the plurality of lenses being positioned with a respective offset of a third plurality of offsets relative to the reference line, wherein the plurality of laser sources and the plurality of lenses, as positioned, are configured to provide beam-steering of the plurality of transmit beams.
Another aspect of the present disclosure is directed to a method for operating a light detection and ranging (LIDAR) device. The method includes providing a plurality of transmit beams via a plurality of laser sources, each laser source of the plurality of laser sources being positioned with a respective offset of a first plurality of offsets relative to a reference line, conditioning the plurality of transmit beams via a plurality of lenses, each lens of the plurality of lenses being positioned with a respective offset of a second plurality of offsets relative to the reference line, and passing the plurality of transmit beams and reflecting received light towards a plurality of detectors via a plurality of transmit/receive (T/R) interfaces, each T/R interface of the plurality of T/R interfaces being positioned with a respective offset of a third plurality of offsets relative to the reference line, wherein the plurality of laser sources and the plurality of lenses, as positioned, provide beam-steering of the plurality of transmit beams.
Another aspect of the present disclosure is directed to a method for manufacturing a light detection and ranging (LIDAR) device. The method includes providing a laser source array including a plurality of laser sources disposed with a first pitch on a first substrate, the plurality of laser sources configured to provide a respective plurality of transmit beams, wherein providing the laser source array comprises positioning at least one laser source of the plurality of laser sources with a first offset relative to a reference line, providing a lens array including a plurality of lenses disposed with a second pitch on a second substrate, the plurality of lenses configured to condition the respective plurality of transmit beams provided by the laser source array, wherein providing the lens array comprises positioning at least one lens of the plurality of lenses with a second offset relative to the reference line, and providing a transmit/receive (T/R) interface array including a plurality of T/R interfaces disposed with a third pitch on a third substrate, the plurality of T/R interfaces configured to pass the respective plurality of transmit beams conditioned by the lens array and to reflect received light towards a plurality of detectors, wherein providing the T/R interface array comprises positioning at least one T/R interface of the plurality of T/R interfaces with a third offset relative to the reference line, wherein the laser source array and the lens array, as positioned, are configured to provide beam steering of one or more of the plurality of transmit beams.
The above and other preferred features, including various novel details of implementation and combination of events, will now be more particularly described with reference to the accompanying figures and pointed out in the claims. It will be understood that the particular systems and methods described herein are shown by way of illustration only and not as limitations. As will be understood by those skilled in the art, the principles and features described herein may be employed in various and numerous embodiments without departing from the scope of any of the present inventions. As can be appreciated from foregoing and following description, each and every feature described herein, and each and every combination of two or more such features, is included within the scope of the present disclosure provided that the features included in such a combination are not mutually inconsistent. In addition, any feature or combination of features may be specifically excluded from any embodiment of any of the present inventions.
The foregoing Summary, including the description of some embodiments, motivations therefor, and/or advantages thereof, is intended to assist the reader in understanding the present disclosure, and does not in any way limit the scope of any of the claims.
The accompanying figures, which are included as part of the present specification, illustrate the presently preferred embodiments and together with the generally description given above and the detailed description of the preferred embodiments given below serve to explain and teach the principles described herein.
While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The present disclosure should be understood to not be limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.
Systems and methods relating to LIDAR devices having linear focal planes are described herein. In at least one embodiment, at least one component included in a LIDAR device is positioned such that the LIDAR device provides micro-optic beam steering. For example, micro-optic beam steering is provided if a lens (e.g., microlens) of a LIDAR channel changes the direction of the chief ray of a laser beam passing through the lens by more than a threshold amount. For example, the laser and/or the lens (e.g., microlens) of a LIDAR channel may be positioned (e.g., relative to each other) to provide micro-optic beam steering. In some examples, the micro-optic beam steering allows the LIDAR device to be included in a device array having a linear (or flat) focal plane arrangement. As such, the size of the LIDAR device array (and the LIDAR system) can be reduced. In certain examples, the time and cost per channel alignment of the LIDAR device array can be reduced by using multi-channel array components that are aligned at the component level.
Reference will now be made in detail to background examples and some embodiments of the invention, examples of which are illustrated in the accompanying drawings. It will be appreciated that, for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the exemplary embodiments described herein may be practiced without these specific details.
Illumination source 160 emits a measurement beam of illumination light 162 in response to an electrical signal (e.g., electrical current) 153. The beam of illumination light 162 may include one or more pulses. In some embodiments, the illumination source 160 is laser based (e.g., a laser diode). In some embodiments, the illumination source is based on one or more light emitting diodes. In general, any suitable illumination source (e.g., pulsed illumination source) may be used. Illumination light 162 exits LIDAR measurement device 100 and reflects from an object in the surrounding 3-D environment under measurement. A portion of the reflected light is collected as return measurement light 171 associated with the illumination light 162. As depicted in
In one aspect, the illumination light 162 is focused and projected toward a particular location in the surrounding environment by one or more beam shaping optical components (collectively, “beam shaping optical assembly”) 163 and a beam scanning device 164 of LIDAR measurement system 100. In a further aspect, the return measurement light 171 is directed and focused onto photodetector 170 by beam scanning device 164 and the one or more beam shaping optical components 163 of LIDAR measurement system 100. The beam scanning device is used in the optical path between the beam shaping optics and the environment under measurement. The beam scanning device effectively expands the field of view and/or increases the sampling density within the field of view of the 3-D LIDAR system.
In the embodiment depicted in
Integrated LIDAR measurement device 130 includes a photodetector 170 having an active sensor area 174. As depicted in
The placement of the waveguide within the acceptance cone of the return light 171 projected onto the active sensing area 174 of detector 170 may be selected to facilitate maximum overlap of the illumination spot and the detector field of view in the far field.
As depicted in
The amplified signal 181 is communicated to return signal receiver IC 150. Receiver IC 150 includes timing circuitry and a time-to-digital converter that estimates the time of flight of the measurement beam from illumination source 160, to a reflective object in the 3-D environment, and back to the photodetector 170. A signal 155 indicative of the estimated time of flight is communicated to master controller 190 for further processing and/or communication to a user of the LIDAR measurement system 100. In addition, return signal receiver IC 150 may be configured to digitize segments of the return signal 181 that include peak values (e.g., return pulses), and communicate signals 156 indicative of the digitized segments to master controller 190. In some embodiments, master controller 190 processes these signal segments to identify properties of the detected object. In some embodiments, master controller 190 communicates signals 156 to a user of the LIDAR measurement system 100 for further processing.
Master controller 190 is configured to generate a measurement command signal 191 (e.g., pulse command signal) that is communicated to receiver IC 150 of integrated LIDAR measurement device 130. Measurement command signal 191 is a digital signal generated by master controller 190. Thus, the timing of measurement command signal 191 is determined by a clock associated with master controller 190. In some embodiments, the measurement command signal 191 is directly used to trigger generation of illumination light 162 by illumination driver IC 152 and data acquisition by receiver IC 150. However, in some embodiments, illumination driver IC 152 and receiver IC 150 do not share the same clock as master controller 190. For this reason, precise estimation of time of flight becomes much more computationally tedious when the measurement command signal 191 is directly used to trigger illumination light generation (e.g., “transmission” or “transmitting” by LIDAR measurement device 130) and data acquisition (“reception” or “receiving” by LIDAR measurement device 130).
In general, a LIDAR measurement system includes a number of different LIDAR measurement devices 130 (e.g., integrated LIDAR measurement devices) each emitting a beam (e.g., pulsed beam) of illumination light from the LIDAR device into the surrounding environment and measuring return light reflected from objects in the surrounding environment.
In these embodiments, master controller 190 communicates a measurement command signal 191 to each different LIDAR measurement device. In this manner, master controller 190 coordinates the timing of LIDAR measurements performed by any number of LIDAR measurement devices. In a further aspect, beam shaping optical components 163 and beam scanning device 164 are in the optical path of the illumination light (e.g., pulses) and return measurement light (e.g., pulses) associated with each of the integrated LIDAR measurement devices. In this manner, beam scanning device 164 directs each illumination light signal and return measurement light signal of LIDAR measurement system 100.
In the depicted embodiment, receiver IC 150 receives measurement command signal 191 and generates a measurement trigger signal VTRG 151 (e.g., pulse trigger signal) in response to the measurement command signal 191. Measurement trigger signal 151 is communicated to illumination driver IC 152 and directly triggers illumination driver IC 152 to electrically couple illumination source 160 to a power supply, thereby generating illumination light 162. In addition, measurement trigger signal 151 directly triggers data acquisition of return signal 181 and associated time of flight calculation. In this manner, measurement trigger signal 151 generated based on the internal clock of receiver IC 150 is used to trigger both illumination light generation and return light data acquisition. This process facilitates precise synchronization of illumination light generation and return light data acquisition, which enables precise time of flight calculations by time-to-distance conversion.
As depicted in
Internal system delays associated with emission of light from the LIDAR system (e.g., signal communication delays and latency associated with the switching components, energy storage components, and pulsed light emitting device) and delays associated with collecting light and generating signals indicative of the collected light (e.g., amplifier latency, analog-digital conversion delay, etc.) can contribute to errors in the estimation of the time of flight of a measurement pulse of light. Thus, measurement of time of flight based on the elapsed time between the rising edge of the measurement trigger signal 151 and each valid return pulse (e.g., 181B and 181C) can introduce undesirable measurement error. In some embodiments, a calibrated, pre-determined delay time is used to compensate for the electronic delays to arrive at a corrected estimate of the actual optical time of flight. However, the accuracy of a static correction to dynamically changing electronic delays is limited. Although frequent re-calibrations may be used to account for such changes, this re-calibration comes at a cost of computational complexity and may interfere with system up-time.
In another aspect, receiver IC 150 may measure time of flight based on the time elapsed between the detection of a detected pulse 181A due to internal cross-talk between the illumination source 160 and photodetector 170 and a valid return pulse (e.g., 181B or 181C). In this manner, systematic delays can be eliminated from the estimation of time of flight. Pulse 181A is generated by internal cross-talk with effectively no distance of light propagation. Thus, the delay in time from the rising edge of the measurement trigger signal to the detection of pulse 181A captures all of the systematic delays associated with illumination and signal detection. By measuring the time of flight of valid return pulses (e.g., return pulses 181B and 181C) with reference to detected pulse 181A, all of the systematic delays associated with illumination and signal detection due to internal cross-talk are eliminated. As depicted in
In some embodiments, the signal analysis is performed by receiver IC 150, entirely. In these embodiments, signals 155 communicated from integrated LIDAR measurement device 130 include an indication of the time of flight determined by receiver IC 150. In some embodiments, signals 156 include digitized segments of return signal 181 generated by receiver IC 150. These raw measurement signal segments are processed further by one or more processors located on board the 3-D LIDAR system, or external to the 3-D LIDAR system to arrive at another estimate of distance, an estimate of one of more physical properties of the detected object, or a combination thereof.
Light emitted from each integrated LIDAR measurement device passes through beam shaping optical assembly 163, which includes beam shaping optical components 116 that collimate the emitted light to generate a beam of illumination light 162 projected from the 3-D LIDAR system into the environment. In this manner, an array of beams of light 105, each emitted from a different LIDAR measurement device, are emitted from 3-D LIDAR system 100 as depicted in
In some embodiments, the 3D LIDAR system 370 includes a LIDAR transceiver (e.g., LIDAR measurement device 130) operable to emit laser beams 376 through the cylindrical shell component 373 of the upper housing 372. In the example of
In some embodiments, the transceiver (e.g., LIDAR measurement device 130) emits each laser beam 376 transmitted by the 3D LIDAR system 370. The direction of each emitted beam may be determined by the angular orientation w of the transceiver's transmitter (e.g., illumination source 160 and mirror component 161) with respect to the system's central axis 374 and by the angular orientation w of the transmitter's movable mirror with respect to the mirror's axis of oscillation (or rotation). For example, the direction of an emitted beam in a horizontal dimension may be determined the transmitter's angular orientation w, and the direction of the emitted beam in a vertical dimension may be determined by the angular orientation w of the transmitter's movable mirror. In one example, the angular orientation w of the transceiver's transmitter corresponds to the angular orientation of the illumination light 162 provided by the illumination source 160 as reflected off the mirror component 161. In some examples, the transmitter's moveable mirror corresponds to a mirror included within the transmitter (or the transceiver); however, in other examples, the moveable mirror may correspond to a mirror that is external to the transmitter (or the transceiver). For example, the angular orientation w of the transmitter's movable mirror may correspond to the angular orientation of the mirror 164.
Alternatively, the direction of an emitted beam in a vertical dimension may be determined by the transmitter's angular orientation w, and the direction of the emitted beam in a horizontal dimension may be determined by the angular orientation w of the transmitter's movable mirror. (For purposes of illustration, the beams of light 375 are illustrated in one angular orientation relative to a non-rotating coordinate frame of the 3D LIDAR system 370 and the beams of light 375′ are illustrated in another angular orientation relative to the non-rotating coordinate frame.)
The 3D LIDAR system 370 may scan a particular point in its field of view by adjusting the orientation ω of the transmitter and the orientation ψ of the transmitter's movable mirror to the desired scan point (ω, ψ) and emitting a laser beam from the transmitter. Likewise, the 3D LIDAR system 370 may systematically scan its field of view by adjusting the orientation ω of the transmitter and the orientation ψ of the transmitter's movable mirror to a set of scan points (ωi, ψj) and emitting a laser beam from the transmitter at each of the scan points.
Assuming that the optical component(s) (e.g., mirror 164) of a LIDAR transceiver remain stationary during the time period after the transmitter emits a laser beam (e.g., a pulsed laser beam or “pulse”) and before the receiver (e.g., photodetector 170) receives the corresponding return beam, the return beam generally forms a spot centered at (or near) a stationary location LO on the detector. This time period is referred to herein as the “ranging period” of the scan point associated with the transmitted beam and the return beam. In some embodiments, the ranging period and the “measurement window” (described below) may be approximately the same.
The laser source 504 is configured to provide a transmit beam (i.e., light) 520 (e.g., illumination light 162) to the lens 506. The lens 506 includes one or more micro-optic lenses configured to provide beam shaping functionality for the laser source 504. The mirror 508a passes the transmit beam 520, and reflects received light 522 (e.g., return measurement light 171) towards the detector 508b. In one example, the mirror 508a may be configured as a pinhole mirror to pass the transmit beam 520 and reflect the received light 522; however, in other examples, the mirror 508a may include a material and/or coating that provides the selective reflection of light. In some examples, the detector 508b is an avalanche photodiode (APD).
Being that the transmit beam 520 represents a single channel, the LIDAR arrangement 502 may direct the transmit beam 520 to a system-level lens 550 (e.g., beam shaping optical assembly 163) before the transmit beam 520 is projected into the environment along with transmit beams from other channels. Likewise, the received light 522 may be directed to the LIDAR arrangement 502 via the lens 550.
As described above, multiple LIDAR devices can be arranged to provide an array of LIDAR devices (e.g., the array 113 of
The LIDAR devices 602 are positioned along a curved focal plane 604. In one example, the LIDAR devices 602 are positioned along the curved focal plane 604 such that each channel is pointing towards the center of the lens 550 (e.g., each channel's light source is oriented such that the chief rays of the beams it emits pass through the center of the lens 550). By physically pointing each channel towards the center of the lens 550, the LIDAR array 600 can achieve overall better system performance (e.g., reduce light clipping at the lens 550). However, due to the unique positioning of each LIDAR device 602, manufacturing the LIDAR device array 600 may involve individually aligning each LIDAR device 602 with respect to the system lens 550. Also, the process of aligning each device 602 individually can be expensive and time consuming. For example, the alignment process for each device may include iteratively tuning the laser source 504 on/off while adjusting the position of the lens 506 and/or the mirror 508a. In other examples, the alignment process may include precise time consuming lateral placement of each device 602 with respect to a reference point (e.g., fiducial) on a suitable mounting platform.
In addition, the unique positioning of each LIDAR device 602 around the curved focal plane 604 can increase the size of the LIDAR device array 600 (and the LIDAR system housing the array 600). For example,
An improved LIDAR device and device array are provided herein. In at least one embodiment, at least one component (e.g., laser source, lens, etc.) included in the LIDAR device is positioned such that the LIDAR device provides micro-optic beam steering. For example, micro-optic beam steering is provided if a lens (e.g., microlens) of a LIDAR channel changes the direction of the chief ray of a laser beam passing through the lens by more than a threshold amount. For example, micro-optic beam steering may be provided if the direction of the chief ray of a laser beam exiting the lens deviates from the direction of the chief ray of the laser beam entering the lens by more than 0.1-0.5 degrees, 0.5-1.0 degrees, 1-2 degrees, 2-5 degrees, 5-10 degrees, 10-20 degrees, or more than 20 degrees. For example, the laser and/or the lens (e.g., microlens) of a LIDAR channel may be positioned (e.g., relative to each other) to provide micro-optic beam steering. In some examples, the micro-optic beam steering allows the LIDAR device to be included in a device array having a linear (or flat) focal plane arrangement. As such, the size of the LIDAR device array (and the LIDAR measurement system) can be reduced. In certain examples, the time and cost per channel alignment of the LIDAR device array can be greatly reduced by using multi-channel array components that are aligned at the component level.
In one example, the components of the LIDAR device 702 are configured to be disposed on a substrate 710 (e.g., common substrate 135). The substrate 710 may be a printed circuit board (PCB). The components may be disposed on a first surface or a second surface of the substrate 710. In the illustrated example, the components are disposed on the first (e.g., top) surface of the substrate 710. In some examples, the components of the LIDAR device 702 may be disposed on the substrate 710 within a common device package; however, in other examples, the substrate 710 may be an external component on which the LIDAR device 702 is disposed. The components of the LIDAR device 702 can be electrically and/or mechanically coupled to the substrate 710.
The position of each component of the LIDAR device 702 is offset relative to a reference line 714. In one example, the reference line 714 corresponds to the center (or boresight) line of a system lens (e.g., system lens 550). In other examples, the reference line 714 may correspond to the next adjacent channel (e.g., a predetermined channel boundary or the nearest component of the adjacent channel). In this context, “offset” corresponds to a distance between a component and the reference line 714. In one example, the laser source 704 is positioned with a first offset Δa, the lens 706 is positioned with a second offset Δb, and the T/R interface 708 is positioned with a third offset Δc. In some examples, the offsets Δa-Δc can be scaled to provide micro-optic beam steering of a transmit beam 712 (e.g., the chief ray of the channel). For example, the LIDAR device 702 can be configured with a first offset Δa that is larger than the second offset Δb and the third offset Δc to steer the transmit beam 712 in a first direction (e.g., a ‘downward’ direction in the illustration of
As described above, the offsets Δa-Δc can be scaled to provide micro-optic beam steering of the transmit beam 712. In this context, “scaled” is used interchangeably with “adjusted” or “modified.” In some examples, scaling the offsets Δa-Δc includes a proportional adjustment of the offsets. In other words, after adjusting a first offset (e.g., Δa), at least one other offset (e.g., Δb and/or Δc) may be subsequently adjusted to maintain a proportional relationship with the first offset. In other examples, scaling the offsets Δa-Δc includes a disproportionate adjustment of one or more offsets relative to the other offsets.
While the LIDAR device 702 is described above as having a ‘downward’ beam steering configuration, it should be appreciated that the LIDAR device 702 can be configured differently. For example, the LIDAR device 702 may be configured with different component offsets to adjust the beam steering direction. In addition, the components of the LIDAR device 702 may be disposed on a different (e.g., opposite) side or region of the substrate 710 to change the beam steering direction. Alternatively, the LIDAR device assembly 700 may be rotated about an axis parallel to the reference line 714 to adjust the beam steering direction.
As described above, the component offsets Δa-Δc can be scaled relative to the reference line 714 to provide micro-optic beam steering of the transmit beam 712. In one example, the LIDAR device 702 can be configured with a first offset Δa, a second offset Δb, and a third offset Δc that are all approximately the same to steer the transmit beam 712 in a boresight direction. In one example, the first offset Δa of the laser source 704, the second offset Δb of the lens 706, and the third offset Δc of the T/R interface 708 may each be approximately 0 um. Due to the relationship between the first offset Δa and the second offset Δb, the transmit beam 712 is provided from the laser source 704 to a center portion of the lens 706, causing the transmit beam 712 to be directed in the boresight direction through the T/R interface 708. As shown, the offsets Δa-Δc can be scaled such that the transmit beam 712 intersects the reference line 714 (e.g., at the center of the system lens).
Similarly,
As described above, the component offsets Δa-Δc can be scaled to provide micro-optic beam steering of the transmit beam 712. Similar to the configuration shown in
In some examples, rather than disposing the components in the lower region of the substrate 710, the configuration of the LIDAR device assembly 800b can be realized by rotating the LIDAR device assembly 700 of
In the examples of
In some examples, being that the LIDAR device 702 is capable of providing micro-optic beam steering, the LIDAR device 702 may be included in a LIDAR array having a linear (or flat) focal plane. For example,
The LIDAR devices 902 are positioned along a flat focal plane 904. In one example, one or more of the LIDAR devices 902 include at least one component positioned to steer the channel (e.g., to steer a beam emitted by the channel) towards the center of the lens 550. For example, the first LIDAR device 902a may be configured as shown in
In some examples, the flat focal plane arrangement of the array 900 allows for a linear channel alignment. As such, the active process of aligning (and/or calibrating) the mirror and/or the lens of the devices 902 may be simplified considerably. In certain examples, the simplified alignment process can reduce the amount of time needed for aligning (and/or calibrating) the array 900, which can decrease manufacturing costs.
While the above examples describe one LIDAR channel per device, it should be appreciated that each of the LIDAR devices may be configured as multi-channel devices. For example, the first LIDAR device 902a may be configured to steer two or more transmit beams in a downward direction towards the center of the lens 550. Likewise, the second LIDAR device 902b may be configured to steer or transmit two or more transmit beams in a boresight direction towards the center of the lens 550. Similarly, the third LIDAR device 902c may be configured to steer two or more transmit beams in an upward direction towards the center of the lens 550. In some examples, all channels within each device 902 may have the same component offset configuration; however, in other examples, at least one channel within each device 902 may have a slightly different component offset configuration than other channels within the same device 902.
In one example, given that the LIDAR devices 902 can be included in a LIDAR array having a linear (or flat) focal plane, the size and cost of the LIDAR array (and the system 100) may be reduced by consolidating the LIDAR devices 902 into a multi-channel LIDAR device.
The laser source array 1004 is configured to provide a plurality of transmit beams (i.e., light) 1020 to the lens array 1006. The lens array 1006 is an array of micro-optic lenses configured to provide beam shaping and steering functionality at the laser source array 1004. The mirror(s) of the T/R interface array 1008 pass(es) the plurality of transmit beams 1020 and reflects received light 1022 towards the detectors of the detector array. In some examples, the detectors of the detector array are avalanche photodiodes (APDs).
The LIDAR arrangement 1002 is configured to provide multiple LIDAR channels. In one example, each transmit beam of the plurality of transmit beams 1020 corresponds to a single channel and is provided from the laser source array 1004 to a corresponding lens of the lens array 1006. Likewise, each detector of the detector array may correspond to a single channel. In one example, the received light 1022 shown in
In one example, the LIDAR arrangement 1002 can be implemented as a LIDAR device having component pitches (e.g., scaled component pitches) that provide micro-optic beam steering to direct the plurality of transmit beams towards the center of the lens 1050. For example,
In one example, the components of the LIDAR device 1102 are configured to be disposed on a substrate 1110. The substrate 1110 may be a printed circuit board (PCB). The components may be disposed on a first surface or a second surface of the substrate 1110. In the illustrated example, the components are disposed on the first (e.g., top) surface of the substrate 1110. In some examples, the components of the LIDAR device 1102 may be disposed on the substrate 1110 within a common device package; however, in other examples, the substrate 1110 may be an external component on which the LIDAR device 1102 is disposed. The components of the LIDAR device 1102 can be electrically and/or mechanically coupled to the substrate 1110.
Similar to the examples described above, each device included in the array components 1104, 1106, and 1108 is positioned with an offset relative to a reference line 1114. For example, the reference line 1114 may correspond to the center (or boresight) line of a system lens (e.g., system lens 1050). As described above, the device offsets can be scaled to provide micro-optic beam steering of a plurality of transmit beams 1112. In some examples, the components 1104, 1106, and 1108 can be configured with scaled device offsets to steer the plurality of transmit beams 1112 in a convergent direction (e.g., towards the center of the lens 1050). In other words, the offset of each device (within a respective array component) can be scaled to adjust the pitch between devices included in each of the components 1104, 1106, and 1108 such that the plurality of transmit beams 1112 converge. For example, the devices included in the components 1104, 1106, and 1108 can be configured such that one or more of channels of the LIDAR device 1102 have a configuration similar to the LIDAR device 702 of
While the LIDAR device 1102 is described above as having a convergent beam steering configuration, it should be appreciated that the LIDAR device 1102 can be configured differently. For example, the devices of each channel included in the components 1104, 1106, and 1108 may be configured with different offsets (or pitches) to adjust the beam steering direction. In addition, the components of the LIDAR device 1102 may be disposed on a different (e.g., opposite) side or region of the substrate 1110 to change the beam steering direction. Alternatively, the LIDAR device assembly 1100 may be rotated about an axis parallel to the reference line 1114 to adjust the beam steering direction. In certain examples, rather than providing a single LIDAR device 1102 having many channels (e.g., 128), it may be beneficial to include several LIDAR devices 1102 in an array (e.g., 4 devices having 32 channels each). As such, the LIDAR device 1102 may be included in a LIDAR array having a linear (or flat) focal plane. For example, the LIDAR device 1102 may be included in the LIDAR device array 900 of
As described above, the LIDAR devices provided herein may enable the size of the device arrays (and corresponding LIDAR systems) to be reduced. For example, the flat focal plane arrangement of the LIDAR device array 900 can enable smaller, more efficient layouts compared to LIDAR device arrays having curved focal planes causing excessive device spacing (e.g., LIDAR device array 600 of
In addition, the compact and efficient nature of the LIDAR devices and device arrays provided herein may enable more channels to be included in LIDAR systems. As such, these LIDAR devices and device arrays can be used to improve the resolution of LIDAR systems while reducing (or maintaining) the size of the system. In some examples, the LIDAR devices 702, 1102 may be advantageously used in space constrained LIDAR applications. For example, the LIDAR devices 702, 1102 may be used in small, handheld LIDAR devices, such as a device included in a mobile phone (or device that plugs into a mobile phone).
In block 1201, a plurality of beams of illumination light (e.g., pulsed illumination light) are emitted into a 3-D environment from a plurality of illumination sources (e.g., pulsed illumination sources). Each of the plurality of beams of illumination light is incident on a beam scanning device.
In block 1202, each of the plurality of beams of illumination light is redirected in a different direction based on an optical interaction between each beam of illumination light and the beam scanning device.
In block 1203, an amount of return light reflected from the 3-D environment illuminated by each beam of illumination light is redirected based on an optical interaction between each amount of return light and the beam scanning device.
In block 1204, each amount of return light reflected from the 3-D environment illuminated by each beam of illumination light is detected (e.g., by a photosensitive detector).
In block 1205, an output signal indicative of the detected amount of return light associated with each beam of illumination light is generated.
In block 1206, a distance between the plurality of illumination sources and one or more objects in the 3-D environment is determined based on a difference between a time when each beam of illumination light is emitted from the LIDAR device and a time when each photosensitive detector detects an amount of light reflected from the object illuminated by the beam of illumination light.
In block 1302, a laser source is provided. In one example, the laser source (e.g., laser source 712) is configured to provide a transmit beam (e.g., configured to emit a laser beam). In some examples, providing the laser source includes positioning the laser source with a first offset relative to a reference line (e.g., reference line 712).
In block 1304, a T/R interface is provided. In one example, the T/R interface (e.g., T/R interface 708) is configured to pass the transmit beam and reflect received light towards a detector. In some examples, providing the T/R interface includes positioning the T/R interface with a second offset relative to the reference line.
In block 1306, a lens is provided. In one example, the lens (e.g., lens 706) is positioned between the laser source and the T/R interface. In some examples, providing the lens includes positioning the lens with a third offset relative to the reference line.
In one example, the components provided in blocks 1302-1306 correspond to a LIDAR device 902 configured to be included in the LIDAR device array 900. In some examples, the components correspond to a single LIDAR channel. In certain examples, the components of the LIDAR device 902 are configured to be disposed on a substrate (e.g., substrate 910). In some examples, the positions of the components (relative to each other, relative to components of other LIDAR devices in the LIDAR device array, or relative to a reference line) correspond to the position of the LIDAR device 902 in the LIDAR device array 900. For example, the LIDAR device 902 may have a position in an upper region of the substrate (e.g., LIDAR device 902a), a middle region of the substrate (e.g., LIDAR device 902b), or a lower region of the substrate (e.g., LIDAR device 902c). It should be appreciated that the regions described above are provided merely as examples and that the LIDAR device 902 may be positioned in different regions of the substrate.
The component offsets of the LIDAR device 902 can be scaled based on the position of the device in the LIDAR device array 900. In one example, the component offsets can be scaled such that the device steers transmitted light towards the center of a system lens (e.g., lens 550). For example, if positioned in the upper region of the substrate, the component offsets can be scaled such that the device steers transmitted light in a first direction (e.g., a downward direction), similar to the LIDAR device 702 of
In block 1308, it is determined if more LIDAR devices 902 are to be added to the LIDAR device array 900. In response to a determination that more LIDAR devices 902 are being added, the method returns to block 1302 and the LIDAR device configuration process repeats. Otherwise, the method continues to block 1310.
In block 1310, the LIDAR devices 902 are aligned to the linear focal plane of the LIDAR device array 900. In some examples, the alignment process includes the use of active alignment equipment (e.g., laser energized equipment) and/or passive alignment equipment (e.g., camera vision equipment). For example, each LIDAR device 902 may be aligned using an active alignment process that includes energizing the laser source and measuring energy (e.g., light) associated with the transmit beam at the center of the system lens 550. In such a process, the alignment of a LIDAR device 902 may be iteratively adjusted until the energy detected in the transmit beam at the center of the system lens 550 meets or exceeds a threshold energy level. As described above, being that the scaled component offsets of the LIDAR devices 902 provide micro-optic beam steering, the LIDAR devices 902 can be arranged with a linear (or flat) focal plane (e.g., focal plane 904). As such, the process of aligning (and/or calibrating) the mirror and/or the lens of each LIDAR device 902 can be simplified considerably. In certain examples, the simplified alignment process can reduce the amount of time and cost needed for aligning (and/or calibrating) the LIDAR device array 900. In some examples, once the alignment is set, the LIDAR devices 902 and/or the LIDAR device components can be coupled, bonded, attached, and/or fastened to the substrate.
In block 1352, a laser source array is provided. In one example, the laser source array (e.g., laser source 1104) includes a plurality of laser sources configured to provide a plurality of transmit beams (e.g., configured to emit a plurality of laser beams). In some examples, providing the laser source array includes positioning each laser source of the plurality of laser sources with a respective offset of a first plurality of offsets relative to a reference line (e.g., reference line 1114). A first pitch between the laser sources included in the laser source array can be scaled to adjust the first plurality of offsets (and the positions of the laser sources). In some examples, the laser source array may be fabricated or pre-assembled on a substrate with the laser sources in the above-described positions (e.g., positioned with the above-described offsets and/or pitch). In some examples, providing the laser source array includes positioning the laser source array (e.g., positioning a first laser source of the laser source array) at a first offset relative to a reference line.
In block 1354, a T/R interface array is provided. In one example, the T/R interface array (e.g., T/R interface array 1108) includes a plurality of T/R interfaces configured to pass the plurality of transmit beams and reflect received light towards a plurality of detectors. In some examples, providing the T/R interface array includes positioning each T/R interface of the plurality of T/R interfaces with a respective offset of a plurality of second offsets relative to the reference line. A second pitch between the T/R interfaces included in the T/R interface array can be scaled to adjust the second plurality of offsets (and the positions of the T/R interfaces). In some examples, the T/R interface array may be fabricated or pre-assembled on a substrate with the T/R interfaces in the above-described positions (e.g., positioned with the above-described offsets and/or pitch). In some examples, providing the T/R interface array includes positioning the T/R interface array (e.g., positioning a first T/R interface of the T/R interface array) at a second offset relative to the reference line.
In block 1356, a lens array is provided. In one example, the lens array (e.g., lens array 1106) is positioned between the plurality of laser sources and the plurality of T/R interfaces. In some examples, providing the lens array includes positioning each lens of the lens array with a respective offset of a third plurality of offsets relative to the reference line. A third pitch between the lenses included in the lens array can be scaled to adjust the third plurality of offsets (and the positions of the lenses). In some examples, the lens array may be fabricated or pre-assembled on a substrate with the lenses in the above-described positions (e.g., positioned with the above-described offsets and/or pitch). In some examples, providing the lens array includes positioning the lens array (e.g., positioning a first lens of the lens array) at a third offset relative to the reference line.
In one example, the array components provided in blocks 1352-1356 correspond to a LIDAR device 1102 configured to be included in the LIDAR device array. In one example, the array components correspond to multiple LIDAR channels. In some examples, the array components 1104, 1106, and 1108 of the LIDAR device 1102 are configured to be disposed on a substrate (e.g., substrate 910). In some examples, the positions of the array components correspond to the position of the LIDAR device 1102 in the LIDAR device array. For example, the LIDAR device 1102 may have a position in an upper region of the substrate (e.g., LIDAR device 902a), a middle region of the substrate (e.g., LIDAR device 902b), or a lower region of the substrate (e.g., LIDAR device 902c). It should be appreciated that the regions described above are provided merely as examples and that the LIDAR device 1102 may be positioned in different regions of the substrate.
The device offsets (or pitches) of the array devices included in each array component 1104, 1106, and 1108 can be scaled based on the position of the LIDAR device 1102 in the LIDAR device array or based on the position of the LIDAR device 1102 relative to a reference line (e.g., a reference line through the center of the system lens). In one example, the device offsets (or pitches) of the array devices can be scaled such that the LIDAR device 1102 transmits light towards the center of a system lens (e.g., lens 550). For example, if positioned in the upper region of the substrate, the device offsets (or pitches) of the array devices can be scaled such that each channel of the LIDAR device 1102 steers transmitted light in a first direction (e.g., a downward direction), similar to the LIDAR device 702 of
In block 1358, it is determined if more LIDAR devices 1102 are to be added to the LIDAR device array. In response to a determination that more LIDAR devices 1102 are being added, the method returns to block 1352 and the LIDAR device configuration process repeats. Otherwise, the method continues to block 1360.
In block 1360, the LIDAR devices 1102 are aligned to the linear focal plane of the LiDAR device array. In some examples, the alignment process includes the use of active alignment equipment (e.g., laser energized equipment) and/or passive alignment equipment (e.g., camera vision equipment). For example, each LIDAR device 1102 may be aligned using an active alignment process that includes energizing at least one laser source of the plurality of laser sources and measuring energy (e.g., light) associated with at least one transmit beam at the center of the system lens 550. In such a process, the alignment of a LIDAR device 1102 and/or the alignment of the array components (1104, 1106, 1108) of the LIDAR device 1102 may be iteratively adjusted until the energy detected in the transmit beam at the center of the system lens 550 meets or exceeds a threshold energy level. For example, the alignment of the LIDAR device 1102 may be adjusted with respect to the reference line 1114 or with respect to the system lens 550. In some examples, the alignment of the array components (1104, 1106, 1108) may be adjusted with respect to each other, with respect to the reference line 1114, or with respect to the system lens 550. As described above, being that the scaled pitches of the LIDAR devices 1102 provide micro-optic beam steering, the LIDAR devices 1102 can be arranged with a linear (or flat) focal plane (e.g., focal plane 904). As such, the active process of aligning (and/or calibrating) the mirror and/or the lens of each LIDAR device can be simplified considerably. In addition, being that the LIDAR devices 1102 include array components, the LIDAR devices 1102 can be aligned at the component level, rather than at the channel level. In certain examples, the simplified alignment process can reduce the amount of time and cost needed for aligning (and/or calibrating) the LIDAR device array. In some examples, once the alignment is set, the LIDAR device and/or the array components 1104, 1106, and 1108 of the LIDAR device 1102 can be coupled, bonded, attached, and/or fastened to an underlying substrate.
Referring to
While the example illustrated in
As described above, the pitches P1-P3 can be scaled to provide micro-optic beam steering of the transmit beam 1112. In this context, “scaled” is used interchangeably with “adjusted,” “selected,” or “modified.” In some examples, scaling the pitches P1-P3 includes a proportional adjustment of the pitches. In other words, after adjusting a pitch (e.g., P1), at least one other pitch (e.g., P2 and/or P3) may be subsequently adjusted to maintain a proportional relationship with the adjusted pitch. In other examples, scaling the pitches P1-P3 includes a disproportionate adjustment of one or more pitches relative to the other pitches.
Referring again to
Program instructions 192 implementing methods such as those described herein may be transmitted over a transmission medium such as a wire, cable, or wireless transmission link. For example, as illustrated in
In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
As described above, an improved integrated LIDAR device and device array is provided herein. In at least one embodiment, the pitch of at least one component included in the LIDAR device is scaled to provide micro-optic beam steering. In some examples, the micro-optic beam steering allows the LIDAR device to be included in a device array having a linear (or flat) focal plane arrangement. As such, the size of the LIDAR device array (and the LIDAR measurement system) can be reduced. In certain examples, the time and cost per channel alignment of the LIDAR device array can be reduced by using multi-channel array components that are aligned at the component level.
As discussed above, some LiDAR systems may use a continuous wave (CW) laser to detect the range and/or velocity of targets, rather than pulsed TOF techniques. Such systems include continuous wave (CW) coherent LiDAR systems and frequency modulated continuous wave (FMCW) coherent LiDAR systems. For example, any of the LiDAR systems (e.g., LiDAR system 100, 210, 300, 400, 800, 900, or 1200) described above can be configured to operate as an FMCW coherent LiDAR system.
In one example, a splitter 1504 provides a first split laser signal Tx1 to a direction selective device 1506, which provides (e.g., forwards) the signal Tx1 to a scanner 1508. In some examples, the direction selective device 1506 is a circulator. The scanner 1508 uses the first laser signal Tx1 to transmit light emitted by the laser 1502 and receives light reflected by the target 1510 (e.g., “reflected light” or “reflections”). The reflected light signal Rx is provided (e.g., passed back) to the direction selective device 1506. The second laser signal Tx2 and reflected light signal Rx are provided to a coupler (also referred to as a mixer) 1512. The mixer may use the second laser signal Tx2 as a local oscillator (LO) signal and mix it with the reflected light signal Rx. The mixer 1512 may be configured to mix the reflected light signal Rx with the local oscillator signal LO to generate a beat frequency fbeat when detected by a differential photodetector 1514. The beat frequency fbeat from the differential photodetector 1514 output is configured to produce a current based on the received light. The current may be converted to voltage by an amplifier (e.g., transimpedance amplifier (TIA)), which may be provided (e.g., fed) to an analog-to-digital converter (ADC) 1516 configured to convert the analog voltage signal to digital samples for a target detection module 1518. The target detection module 1518 may be configured to determine (e.g., calculate) the radial velocity of the target 1510 based on the digital sampled signal with beat frequency fbeat.
In one example, the target detection module 1518 may identify Doppler frequency shifts using the beat frequency fbeat and determine the radial velocity of the target 1510 based on those shifts. For example, the velocity of the target 1510 can be calculated using the following relationship:
where, fd is the Doppler frequency shift, λ is the wavelength of the laser signal, and vt is the radial velocity of the target 1510. In some examples, the direction of the target 1510 is indicated by the sign of the Doppler frequency shift fd. For example, a positive signed Doppler frequency shift may indicate that the target 1510 is traveling towards the system 1500 and a negative signed Doppler frequency shift may indicate that the target 1510 is traveling away from the system 1500.
In one example, a Fourier Transform calculation is performed using the digital samples from the ADC 1516 to recover the desired frequency content (e.g., the Doppler frequency shift) from the digital sampled signal. For example, a controller (e.g., target detection module 1518) may be configured to perform a Discrete Fourier Transform (DFT) on the digital samples. In certain examples, a Fast Fourier Transform (FFT) can be used to calculate the DFT on the digital samples. In some examples, the Fourier Transform calculation (e.g., DFT) can be performed iteratively on different groups of digital samples to generate a target point cloud.
While the LiDAR system 1500 is described above as being configured to determine the radial velocity of a target, it should be appreciated that the system can be configured to determine the range and/or radial velocity of a target. For example, the LIDAR system 1500 can be modified to use laser chirps to detect the velocity and/or range of a target.
In other examples, the laser frequency can be “chirped” by modulating the phase of the laser signal (or light) produced by the laser 1602. In one example, the phase of the laser signal is modulated using an external modulator placed between the laser source 1602 and the splitter 1604; however, in some examples, the laser source 1602 may be modulated directly by changing operating parameters (e.g., current/voltage) or include an internal modulator. Similar to frequency chirping, the phase of the laser signal can be increased (“ramped up”) or decreased (“ramped down”) over time.
Some examples of systems with FMCW-based LiDAR sensors have been described. However, the techniques described herein may be implemented using any suitable type of LiDAR sensors including, without limitation, any suitable type of coherent LiDAR sensors (e.g., phase-modulated coherent LiDAR sensors). With phase-modulated coherent LiDAR sensors, rather than chirping the frequency of the light produced by the laser (as described above with reference to FMCW techniques), the LiDAR system may use a phase modulator placed between the laser 1602 and the splitter 1604 to generate a discrete phase modulated signal, which may be used to measure range and radial velocity.
As shown, the splitter 1604 provides a first split laser signal Tx1 to a direction selective device 1606, which provides (e.g., forwards) the signal Tx1 to a scanner 1608. The scanner 1608 uses the first laser signal Tx1 to transmit light emitted by the laser 1602 and receives light reflected by the target 1610. The reflected light signal Rx is provided (e.g., passed back) to the direction selective device 1606. The second laser signal Tx2 and reflected light signal Rx are provided to a coupler (also referred to as a mixer) 1612. The mixer may use the second laser signal Tx2 as a local oscillator (LO) signal and mix it with the reflected light signal Rx. The mixer 1612 may be configured to mix the reflected light signal Rx with the local oscillator signal LO to generate a beat frequency fbeat. The mixed signal with beat frequency fbeat may be provided to a differential photodetector 1614 configured to produce a current based on the received light. The current may be converted to voltage by an amplifier (e.g., a transimpedance amplifier (TIA)), which may be provided (e.g., fed) to an analog-to-digital converter (ADC) 1616 configured to convert the analog voltage to digital samples for a target detection module 1618. The target detection module 1618 may be configured to determine (e.g., calculate) the range and/or radial velocity of the target 1610 based on the digital sampled signal with beat frequency fbeat.
Laser chirping may be beneficial for range (distance) measurements of the target. In comparison, Doppler frequency measurements are generally used to measure target velocity. Resolution of distance can depend on the bandwidth size of the chirp frequency band such that greater bandwidth corresponds to finer resolution, according to the following relationships:
where c is the speed of light, BW is the bandwidth of the chirped laser signal, fbeat is the beat frequency, and TChirpRamp is the time period during which the frequency of the chirped laser ramps up (e.g., the time period corresponding to the up-ramp portion of the chirped laser). For example, for a distance resolution of 3.0 cm, a frequency bandwidth of 5.0 GHz may be used. A linear chirp can be an effective way to measure range and range accuracy can depend on the chirp linearity. In some instances, when chirping is used to measure target range, there may be range and velocity ambiguity. In particular, the reflected signal for measuring velocity (e.g., via Doppler) may affect the measurement of range. Therefore, some exemplary FMCW coherent LiDAR systems may rely on two measurements having different slopes (e.g., negative and positive slopes) to remove this ambiguity. The two measurements having different slopes may also be used to determine range and velocity measurements simultaneously.
The positive slope (“Slope P”) and the negative slope (“Slope N”) (also referred to as positive ramp (or up-ramp) and negative ramp (or down-ramp), respectively) can be used to determine range and/or velocity. In some instances, referring to
where fbeat_P and fbeat_N are beat frequencies generated during positive (P) and negative (N) slopes of the chirp 1702 respectively and λ is the wavelength of the laser signal.
In one example, the scanner 1608 of the LiDAR system 1600 is used to scan the environment and generate a target point cloud from the acquired scan data. In some examples, the LiDAR system 1600 can use processing methods that include performing one or more Fourier Transform calculations, such as a Fast Fourier Transform (FFT) or a Discrete Fourier Transform (DFT), to generate the target point cloud from the acquired scan data. Being that the system 1600 is capable of measuring range, each point in the point cloud may have a three-dimensional location (e.g., x, y, and z) in addition to radial velocity. In some examples, the x-y location of each target point corresponds to a radial position of the target point relative to the scanner 1608. Likewise, the z location of each target point corresponds to the distance between the target point and the scanner 1608 (e.g., the range). In one example, each target point corresponds to one frequency chirp 1702 in the laser signal. For example, the samples collected by the system 1600 during the chirp 1702 (e.g., t1 to t6) can be processed to generate one point in the point cloud.
The memory 1820 stores information within the system 1800. In some implementations, the memory 1820 is a non-transitory computer-readable medium. In some implementations, the memory 1820 is a volatile memory unit. In some implementations, the memory 1820 is a non-volatile memory unit.
The storage device 1830 is capable of providing mass storage for the system 1800. In some implementations, the storage device 1830 is a non-transitory computer-readable medium. In various different implementations, the storage device 1830 may include, for example, a hard disk device, an optical disk device, a solid-date drive, a flash drive, or some other large capacity storage device. For example, the storage device may store long-term data (e.g., database data, file system data, etc.). The input/output device 1840 provides input/output operations for the system 1800. In some implementations, the input/output device 1840 may include one or more of a network interface devices, e.g., an Ethernet card, a serial communication device, e.g., an RS-232 port, and/or a wireless interface device, e.g., an 802.11 card, a 3G wireless modem, or a 4G wireless modem. In some implementations, the input/output device may include driver devices configured to receive input data and send output data to other input/output devices, e.g., keyboard, printer and display devices 1860. In some examples, mobile computing devices, mobile communication devices, and other devices may be used.
In some implementations, at least a portion of the approaches described above may be realized by instructions that upon execution cause one or more processing devices to carry out the processes and functions described above. Such instructions may include, for example, interpreted instructions such as script instructions, or executable code, or other instructions stored in a non-transitory computer readable medium. The storage device 1830 may be implemented in a distributed way over a network, for example as a server farm or a set of widely distributed servers, or may be implemented in a single computing device.
Although an example processing system has been described in
The term “system” may encompass all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. A processing system may include special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). A processing system may include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
A computer program (which may also be referred to or described as a program, software, a software application, a module, a software module, a script, or code) can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and it can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
The processes and logic flows described in this specification can be performed by one or more programmable computers executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).
Computers suitable for the execution of a computer program can include, by way of example, general or special purpose microprocessors or both, or any other kind of central processing unit. Generally, a central processing unit will receive instructions and data from a read-only memory or a random access memory or both. A computer generally includes a central processing unit for performing or executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices.
Computer readable media suitable for storing computer program instructions and data include all forms of nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; and magneto optical disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.
While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.
Particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing may be advantageous. Other steps or stages may be provided, or steps or stages may be eliminated, from the described processes. Accordingly, other implementations are within the scope of the following claims.
As illustrated in
A number of controllers and peripheral devices may also be provided, as shown in
In the illustrated system, all major system components may connect to a bus 1916, which may represent more than one physical bus. However, various system components may or may not be in physical proximity to one another. For example, input data and/or output data may be remotely transmitted from one physical location to another. In addition, programs that implement various aspects of some embodiments may be accessed from a remote location (e.g., a server) over a network. Such data and/or programs may be conveyed through any of a variety of machine-readable medium including, but are not limited to: magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and holographic devices; magneto-optical media; and hardware devices that are specially configured to store or to store and execute program code, such as application specific integrated circuits (ASICs), programmable logic devices (PLDs), flash memory devices, and ROM and RAM devices. Some embodiments may be encoded upon one or more non-transitory computer-readable media with instructions for one or more processors or processing units to cause steps to be performed. It shall be noted that the one or more non-transitory computer-readable media shall include volatile and non-volatile memory. It shall be noted that alternative implementations are possible, including a hardware implementation or a software/hardware implementation. Hardware-implemented functions may be realized using ASIC(s), programmable arrays, digital signal processing circuitry, or the like. Accordingly, the “means” terms in any claims are intended to cover both software and hardware implementations. Similarly, the term “computer-readable medium or media” as used herein includes software and/or hardware having a program of instructions embodied thereon, or a combination thereof. With these implementation alternatives in mind, it is to be understood that the figures and accompanying description provide the functional information one skilled in the art would require to write program code (i.e., software) and/or to fabricate circuits (i.e., hardware) to perform the processing required.
It shall be noted that some embodiments may further relate to computer products with a non-transitory, tangible computer-readable medium that have computer code thereon for performing various computer-implemented operations. The media and computer code may be those specially designed and constructed for the purposes of the techniques described herein, or they may be of the kind known or available to those having skill in the relevant arts. Examples of tangible computer-readable media include, but are not limited to: magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and holographic devices; magneto-optical media; and hardware devices that are specially configured to store or to store and execute program code, such as application specific integrated circuits (ASICs), programmable logic devices (PLDs), flash memory devices, and ROM and RAM devices. Examples of computer code include machine code, such as produced by a compiler, and files containing higher level code that are executed by a computer using an interpreter. Some embodiments may be implemented in whole or in part as machine-executable instructions that may be in program modules that are executed by a processing device. Examples of program modules include libraries, programs, routines, objects, components, and data structures. In distributed computing environments, program modules may be physically located in settings that are local, remote, or both.
One skilled in the art will recognize no computing system or programming language is critical to the practice of the techniques described herein. One skilled in the art will also recognize that a number of the elements described above may be physically and/or functionally separated into sub-modules or combined together.
The phrasing and terminology used herein are for the purpose of description and should not be regarded as limiting.
The term “approximately”, the phrase “approximately equal to”, and other similar phrases, as used in the specification and the claims (e.g., “X has a value of approximately Y” or “X is approximately equal to Y”), should be understood to mean that one value (X) is within a predetermined range of another value (Y). The predetermined range may be plus or minus 20%, 10%, 5%, 3%, 1%, 0.1%, or less than 0.1%, unless otherwise indicated.
The indefinite articles “a” and “an,” as used in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” The phrase “and/or,” as used in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.
As used in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.
As used in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.
The use of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof, is meant to encompass the items listed thereafter and additional items.
Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed. Ordinal terms are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term), to distinguish the claim elements.
Although certain specific embodiments are described above for instructional purposes, the teachings of this disclosure have general applicability and are not limited to the specific embodiments described above. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.
