Various embodiments of the present disclosure are generally directed to an apparatus and method for rebalancing a field of view (FoV) of an active light detection system.
Without limitation, some embodiments operate to identify a region of interest within a baseline FoV, and an emitter is adjusted to apply an enhanced amount of electromagnetic radiation to the region of interest. A detector is used to identify at least one target in the region of interest responsive to the enhanced amount of electromagnetic radiation applied to the region of interest. A common light source can be used to both illuminate the baseline FoV as well as supply the enhanced energy to the region of interest. Different energy densities can be supplied to the respective areas. A rotatable polygon, micromirrors, galvanometers, and/or solid state array mechanisms can be used to divert the pulses to the region of interest.
These and other features and advantages of various embodiments disclosed herein can be understood from the following detailed description in conjunction with a review of the accompanying drawings.
Various embodiments of the present disclosure are generally directed to optimization of an active light detection system.
Light Detection and Ranging (LiDAR) systems are useful in a number of applications in which ranges (e.g., distances) from an emitter to a target are detected by irradiating the target with electromagnetic radiation in the form of light. The range is detected in relation to timing characteristics of reflected light received back by the system. LiDAR applications include topographical mapping, guidance, surveying, and so on. One increasingly popular application for LiDAR is in the area of autonomously piloted or driver assisted vehicle guidance systems (e.g., self driving cars, autonomous drones, etc.). While not limiting, the light wavelengths used in a typical LiDAR system may range from ultraviolet to near infrared (e.g., 250 nanometers, nm to 1000 nm or more). Other wavelength ranges can be used.
One commonly employed form of LiDAR is sometimes referred to as coherent pulsed LiDAR, which generally uses coherent light and detects the range based on detecting phase differences in the reflected light. Such systems may use a dual (IQ) channel detector with an I (in-phase) channel and a Q (quadrature) channel. Other forms of LiDAR systems can be used, however, including non-coherent light systems that may incorporate one or more detection channels. Further alternatives that can be incorporated into LiDAR systems include systems that sweep the emitted light using mechanical based systems that utilize moveable mechanical elements, solid-state systems with no moving mechanical parts but instead use phase array mechanisms to sweep the emitted light in a direction toward the target, and so on.
While operable, these and other forms of LiDAR systems can have difficulty providing accurate detection resolution in all desired areas under all operating conditions. In particular, it may be desirable at times to provide enhanced detection to particular regions of interest within the field of view (FoV) of the system.
Various embodiments of the present disclosure are accordingly directed to a method and apparatus for providing enhanced detection capabilities in a LiDAR system. As explained below, some embodiments provide a processing sequence (e.g., algorithm) for automatically adjusting the laser output level or fire rate based on a region of interest priority scheme. In this way, enhanced detection response can be provided. The adjustments can be automatic or user selected, as desired.
These and other features and advantages of various embodiments can be understood beginning with a review of
The LiDAR system 100 includes a controller 104 which provides top level control of the system. The controller 104 can take any number of desired configurations, including hardware and/or software. In some cases, the controller can include the use of one or more programmable processors with associated programming (e.g., software, firmware) stored in a local memory which provides instructions that are executed by the programmable processor(s) during operation. Other forms of controllers can be used, including hardware based controllers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), system on chip (SOC) integrated circuits, application specific integrated circuits (ASICs), gate logic, reduced instruction set computers (RISCs), etc.
An energy source circuit 106, also sometimes referred to as an emitter or a transmitter, operates to direct electromagnetic radiation in the form of light pulses toward the target 102. A detector circuit 108, also sometimes referred to as a receiver or a sensor, senses reflected light pulses received back from the target 102. The controller 104 directs operation of the emitted light from the emitter 106, denoted by arrow 110, and decodes information from the reflected light obtained back from the target, as denoted by arrow 112.
Arrow 114 depicts the actual, true range information associated with the intervening distance (or other range parameter) between the LiDAR system 100 and the target 102. Depending on the configuration of the system, the range information can include the relative or absolute speed, velocity, acceleration, distance, size, location, reflectivity, color, surface features and/or other characteristics of the target 102 with respect to the system 100.
The decoded range information can be used to carry out any number of useful operations, such as controlling a motion, input or response of an autonomous vehicle, generating a topographical map, recording data into a data structure for further analysis and/or operations, etc. The controller 104 perform these operations directly, or can communicate the range information to an external system 116 for further processing and/or use.
In some cases, inputs supplied by the external system 116 can activate and configure the system to capture particular range information, which is then returned to the external system 116 by the controller 104. The external system can take any number of suitable forms, and may include a system controller (such as CPU 118), local memory 120, etc. The external system may form a portion of a closed-loop control system and the range information output by the LiDAR system 100 can be used by the external system 116 to adjust the position of a moveable element.
The controller 104 can incorporate one or more programmable processors (CPU) 122 that execute program instructions in the form of software/firmware stored in a local memory 124, and which communicate with the external controller 118. External sensors 126 can provide further inputs used by the external system 116 and/or the LiDAR system 100.
Regardless the configuration of the output system,
A low pass filter (LPF) 406 and an analog to digital converter (ADC) 408 can be used as desired to provide processing of the input pulses. A processing circuit 410 provides suitable signal processing operations to generate a useful output 412.
Within the FoV are denoted selected regions of interest, such as regions 1 and 2, represented at 506 and 508. These regions of interest can be any selected areas. For example, in the context of a projectile, a region of interest may be calculated as an area into which the object with which the system is associated is expected to penetrate in the near future. In the context of a vehicle, a region of interest may be locations where important information may appear (e.g., road signs, pedestrians, etc.). Substantially any subset of an overall FoV may be deemed a region of interest, and this may change at different times under different circumstances. In some cases, system inputs may trigger the focusing of the system on particular areas as a region of interest. In this way, the context of a region of interest is not necessarily a fixed location within the FoV, but rather, may be time and circumstance dependent.
In some embodiments, greater and or higher power is applied to the emitter to scan the region of interest. In other embodiments, adjustments are made so that a greater percentage than normal of the available scanning is supplied to the region of interest (e.g., the beams emitted by the system are directed to spend more time or provide greater amounts of power upon the selected region). In still other embodiments, pulse rates are increased so that relatively more pulses are directed toward target(s) in the region of interest.
In this way, a region of interest can be identified based on various inputs (including automated inputs or user selected inputs) and greater focus is applied to the region(s) of interest in detecting range information for target(s) that may appear in such regions of interest.
The FoV 700 is spanned by beam points 702 that are rasterized along respective orthogonal directions x and y so as to be arranged along rows 704 and columns 706. In some embodiments, the beam points 702 are issued as pulses that rasterize, or scan, the entirety of the window of the FoV such as along each row in turn. A complete scanning of the entirety of the window is referred to as a frame. Many such frames are obtained over each unit of time (e.g., many frames are obtained per second, etc.).
Depending on the configuration of the system, there will be many more beam points 702 supplied along each row 704 and column 706 than those shown in
Regardless, in general
A particular region of interest is identified as area (FoV) 810, which defines a subset of the overall FoV 800. The FoV 810 is similarly rasterized by beam points 812. The points 812 are arranged along rows 814 and columns 816 arranged along the orthogonal x-y axes as before, although such is not necessarily required. It can be seen that the FoV 810 has a significantly higher density and resolution as compared to the baseline FoV 810 (and FoV 700 in
The FoV 810 may also be subjected to a higher frame rate as compared to the FoV 700/800, so that not only are the beams 812 closer together (e.g., there is a greater density of rows and columns in FoV 810), but the cyclical rasterization of the beams 812 may be at a higher rate as compared to the beams 702, 802 as well. In this way, greater amounts of energy are directed to the FoV 810 by the system to track, with greater resolution, targets disposed within this enhanced window.
In some cases, the beam points 702 and 802 within the baseline areas of FoVs 700, 800 are nominally identical to the beam points 812 within enhanced FoV 810; that is, all of these respective beams can have nominally the same frequency, wavelength, amplitude, pulse count, timing, duration, and so on. The difference in this case is that the beams supplied to the enhanced FoV area 810 are simply more dense than in other areas within the rest of the FoV. Stated another way, more pulses are directed into the area 810 as compared to the rest of the area 800 (and the area 700).
In other cases, differences are supplied in terms of waveform characteristics provided to the enhanced FoV area 810 as compared to the baseline pulses supplied to the rest of the FoV area 700/800. In this way, significantly greater amounts of energy can be diverted to the enhanced FoV area 810. In still further cases, a reduction can be made in the average energy density to the rest of area 800 not included within area 810 so that fewer and/or lower energy pulses are provided to areas of lesser interest while the energy is directed to the area of greater interest.
Reflected from the target is a received set of pulses 912 including pulses 914 (pulse P1) and 916 (pulse P2). The time of flight (TOF) value for pulse P1 is denoted at 918. Similar TOF values are provided for each pulse in turn. Range information including distance and other parameters can be calculated responsive to the TOF values of the respective pulses.
The received P1 pulse 914 may undergo frequency doppler shifting and other distortions as compared to the emitted P1 pulse 904. The same is generally true for each successive sets of transmitted and received pulses such as the P2 pulses 906, 916. In some cases, this detected doppler shift information can be used to provide range information, such as but not including relative velocity between the target and the emitter, etc. Regardless, the frequencies, phase and/or amplitudes of the received pulses 914, 916 will be processed as described above to enable the detector circuit to correctly match the respective pulses and obtain accurate distance and other range information.
Because the area of interest is provided with greater levels of energy and decoding resources, it may be advantageous in some applications to provide a broad spectrum range of wavelengths, amplitudes and phase shifts to the pulses supplied in order to obtain the desired granularity of range information for targets therewithin. While a single pulse is shown for normal operation and multiple pulses are shown for enhanced operation, such is merely exemplary of some embodiments and is not limiting. In other embodiments, the same number and types of pulses can be provided to both the baseline and enhanced FoV areas, with a greater frame rate, density, amplitude, or other factor being used to direct a higher average energy level to the enhanced area (e.g., 810) as compared to the baseline area (e.g., 700 or 800 outside area 810).
A LiDAR system such as 100 in
The system commences with normal operation at block 1106. This can include scans of the baseline FoV as depicted in
Reflected pulses from various targets within the baseline FoV will be detected by a detector such as depicted in
At some point during continued operation of the system, an area of interest within the baseline FoV will be identified as shown by block 1010. The size, location and distance of the enhanced area, also referred to as an enhanced FoV, will depend on the requirements of a given application. For example, during detected high speed travel conditions (such as indicated by other sensors such as a GPS, a speedometer, etc.), it may be desirable to provide a long range scan window in the central portion of the baseline FoV to detect high speed vehicles or other elements that may be of interest. Other situations will readily occur to the skilled artisan where an enhanced field of interest (enhanced FoV) may be selected.
Once selected, the enhanced FoV is subjected to enhanced scan energies at block 1012. This can include a higher density of beam points, different frequencies, amplitudes, pulse counts, etc. In some cases, pulses that would have otherwise been dedicated to the rest of the baseline FoV can be instead diverted to the enhanced FoV While it is contemplated that a single source will be utilized to provide the beams in both the baseline FoV and the enhanced FoV, in further embodiments additional sources can be brought online to provide the enhanced FoV scanning.
Regardless of the manner in which the system is adaptively configured, the enhanced FoV receives enhanced scanning resolution. In response, the optical element Range information for targets detected within the enhanced area is obtained during block 1014 and processed accordingly. In some embodiments, range information associated with the baseline scan can be used to implement the enhanced scan operation of blocks 1010-1014. In other embodiments, range information associated with the enhanced scan (including lack thereof of any particularly useful information) can be used to transition the system back to baseline scanning without the additional scanning of the enhanced FoV. Other operational configurations will readily occur to the skilled artisan in view of the foregoing discussion.
As noted above, the system can cycle to provide different scanning patterns for different areas as required.
The manager circuit 1202 uses a number of inputs including system configuration information, measured distance for various targets, various other sensed parameters from the system (including external sensors 126), history data accumulated during prior operation, and user selectable inputs. Other inputs can be used as desired.
The manager circuit 1202 uses these and other inputs to provide various outputs including accumulated history data 1204 and various profiles 1206, both of which can be stored in local memory such as 124 for future reference. The history data 1204 can be arranged as a data structure providing relevant history and system configuration information. The profiles 1206 can describe different pulse set configurations with different numbers of pulses at various frequencies and other configuration settings, as well as other appropriate gain levels, ranges and slopes for different sizes, types, distances and velocities of detected targets.
The manager circuit 1202 further operates to direct various control information to an emitter (transmitter Tx) 1208 and a detector (receiver Rx) 1210 to implement these respective profiles. It will be understood that the Tx and Rx 1208, 1210 correspond to the various emitters and detectors described above. Without limitation, the inputs to the Tx 1208 can alter the pulses being emitted in the area of interest (including actuation signals to selectively switch in the specially configured lens or other optical element), and the inputs to the Rx 1210 can include gain, timing and other information to equip the detector to properly decode the pulses from the enhanced resolution area of interest.
As described previously, different gain ranges can be selected and used for different targets within the same FoV. Closer targets within the point cloud can be provided with one range with a lower slope and magnitude values to obtain optimal resolution of the closer targets, while at the same time farther targets within the point cloud can be provided with one or more different gain ranges with higher slopes and/or different magnitude values to obtain optimal resolution of the farther targets. It will be noted that the baseline scan can be maintained at a constant level with variable scans switched into operation over substantially any subset area of the baseline scan, including but not limited to substantially all of the baseline FoV, at least for limited periods of time.
Energy budget issues can be a concern, so that the energy supplied to the enhanced scanning can be carried out for a selected period of time (e.g., 10 minutes, etc.), after which the system defaults to normal baseline scanning. Events can be used as triggers to enhance the scans, such as the detection of relatively high velocity targets or targets that may have a calculated trajectory that is of concern, at which time the system can implement the enhanced scanning techniques described above until such time that the need for continued scanning is deemed to be passed.
It can now be understood that various embodiments provide a LiDAR system with the capability of emitting light pulses over a selected FoV, along with a specially configured enhancement feature that, when switched into the system, directs at least some of the energy from the emitter into a reduced sized area of interest within the FoV with a corresponding aspect of range. Any number of different alternatives will readily occur to the skilled artisan in view of the foregoing discussion.
While coherent, I/Q based systems have been contemplated as a basic environment in which various embodiments can be practiced, such are not necessarily required. Any number of different types of systems can be employed, including solid state, mechanical, galvanometer based systems, micromirror arrangements, rotatable polygons, etc.
It is to be understood that even though numerous characteristics and advantages of various embodiments of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the disclosure, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
The present application makes a claim of domestic priority to U.S. Provisional Patent Application No. 63/217,872 filed Jul. 2, 2021, the contents of which are hereby incorporated by reference.
Number | Date | Country | |
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63217872 | Jul 2021 | US |