CN114545427A - Distance measuring system, method and computer readable storage medium - Google Patents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
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Abstract
The application is applicable to the technical field of flight time, and provides a distance measuring system, a distance measuring method and a computer readable storage medium, wherein the distance measuring system comprises a transmitter, a collector and a processing circuit connected with the transmitter and the collector; wherein, the emitter is used for emitting a pulse light beam to the target; the collector comprises a pixel unit and a grating, the pixel unit comprises a plurality of sensing areas, a preset distance is formed between the grating and the pixel unit, a plurality of light spots are formed on the surface of the pixel unit after pulse light beams reflected by a target are diffracted by the grating, and the sensing areas are used for collecting photons in the light spots and outputting photon signals; the processing circuit is used for calculating a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit, and performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam, so that the accuracy of the distance obtained based on the second flight time measurement can be effectively improved.
Description
Technical Field
The present application relates to Time of flight (TOF) technologies, and in particular, to a distance measuring system, method and computer-readable storage medium.
Background
Distance measurement systems based on time-of-flight technology have been widely used in the fields of consumer electronics, unmanned driving, virtual reality, augmented reality, and the like. A distance measuring system based on a time-of-flight technique generally includes an emitter and a collector, a pulse beam is irradiated to a target by the emitter and a pulse beam reflected by the target is received by the collector, and a distance between the target and the distance measuring system is calculated by calculating a time from when the pulse beam is emitted to when the pulse beam is received. However, the conventional distance measurement system is interfered by ambient light noise, signal light shot noise, collector noise and the like, so that the measured distance includes a certain error, and the distance measured at different times under the same scene fluctuates greatly.
Disclosure of Invention
In view of this, embodiments of the present application provide a distance measurement system, a distance measurement method, and a computer-readable storage medium, so as to solve the problems that, in an existing distance measurement system, a measured distance includes a certain error due to interference of ambient light noise, signal light shot noise, collector noise, and the like, and distance fluctuation obtained by measurement is large at different times in the same scene.
A first aspect of an embodiment of the present application provides a distance measurement system, including a transmitter, a collector, and a processing circuit connected to the transmitter and the collector;
the transmitter is used for transmitting a pulse light beam to a target;
the collector comprises a pixel unit and a grating, the pixel unit comprises a plurality of sensing areas, a preset distance is formed between the grating and the pixel unit, a plurality of light spots are formed on the surface of the pixel unit after pulse light beams reflected by a target are diffracted by the grating, and the sensing areas are used for collecting photons in the light spots and outputting photon signals;
and the processing circuit is used for calculating a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit and performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam.
A second aspect of the embodiments of the present application provides a distance measurement method implemented based on the distance measurement system provided in the first aspect of the embodiments of the present application, including the following steps implemented by a processing circuit:
controlling the transmitter to transmit a pulse beam to the target;
controlling a pixel unit to collect a plurality of light spots formed on the surface of the pixel unit after the pulse light beam reflected by the target is diffracted by the grating;
and calculating a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit, and performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam.
A third aspect of embodiments of the present application provides a computer-readable storage medium, in which a computer program is stored, which, when executed by a processing circuit, implements the steps of the distance measurement method according to the second aspect of embodiments of the present application.
A distance measurement system provided in a first aspect of an embodiment of the present application includes a transmitter, a collector, and a processing circuit connected to the transmitter and the collector; a transmitter for transmitting a pulsed light beam to a target; the collector comprises a pixel unit and a grating, the pixel unit comprises a plurality of sensing areas, a preset distance is formed between the grating and the pixel unit, a plurality of light spots are formed on the surface of the pixel unit after pulse light beams reflected by a target are diffracted by the grating, and the sensing areas are used for collecting photons in the light spots and outputting photon signals; the processing circuit is used for calculating a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit, performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam, performing independent, multiple and simultaneous acquisition by dispersing the pulse light beam into a plurality of independent light spots and projecting the light spots to different sensing areas to obtain a plurality of photon signals, calculating a plurality of first flight times, and performing curve fitting on the plurality of first flight times to obtain a second flight time, so that the precision of the distance obtained based on the second flight time measurement can be effectively improved.
It is understood that, the beneficial effects of the second aspect and the third aspect can be referred to the related description of the first aspect, and are not described herein again.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a distance measurement system provided in an embodiment of the present application;
fig. 2 is a first schematic diagram of a pixel unit and a light spot provided in an embodiment of the present application;
fig. 3 is a second schematic diagram of a pixel unit and a light spot provided in an embodiment of the present application;
fig. 4 is a schematic structural diagram of a collector provided in an embodiment of the present application;
fig. 5 is a schematic structural diagram of a pixel unit and a processing circuit provided in an embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known devices, systems, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or arrays, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, arrays, and/or groups thereof.
Furthermore, in the description of the present application and the appended claims, the terms "first," "second," "third," and the like are used for distinguishing between descriptions and not necessarily for describing or implying relative importance.
Reference throughout this specification to "one embodiment" or "some embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, appearances of the phrase "in one embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but rather "one or more, but not all embodiments" unless specifically stated otherwise. The term "include" and variations thereof mean "including but not limited to", unless expressly specified otherwise.
As shown in fig. 1, an embodiment of the present application provides a distance measuring system 100, which includes a transmitter 1, a collector 2, and a processing circuit 3 connected to the transmitter 1 and the collector 2;
a transmitter 1 for transmitting a pulsed light beam 300 to a target 200;
the collector 2 comprises a pixel unit 21 and a grating 22, the pixel unit 21 comprises a plurality of sensing areas, a preset distance is formed between the grating 22 and the pixel unit 21, a plurality of light spots are formed on the surface of the pixel unit 21 after the pulse light beam 400 reflected by the target 200 is diffracted by the grating, and the sensing areas are used for collecting photons in the light spots and outputting photon signals;
and the processing circuit is used for calculating a plurality of first flight times of the pulse light beam according to the plurality of photon signals output by the pixel unit 21, and performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam.
In application, the target may be any object in free space. At least part of the pulse beams emitted to the target by the emitter are reflected to the collector by the target, so that the pulse beams reflected by the target form a plurality of light spots on the surface of the pixel unit after being diffracted by the grating, and at least part of sensing areas in the pixel unit can independently and simultaneously collect the pulse beams reflected by the target for a plurality of times and carry out photoelectric conversion to obtain corresponding photon signals, and then the photon signals are output to the processing circuit. The processing circuit calculates a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit, then performs curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam, and the distance between the target and the distance measuring system can be calculated based on the second flight time. The processing circuit is used for synchronously sending a trigger signal to the emitter and the collector so as to synchronously trigger the emitter to emit a pulse beam and the collector to collect a plurality of light spots formed on the surface of the pixel unit after the pulse beam reflected by the target is diffracted by the grating. The trigger signal may be a clock signal. The calculation formula of the distance between the target and the distance measuring system is as follows:
where D represents the distance between the target and the distance measuring system, c represents the speed of light,
representing a second time of flight.
In application, the emitter comprises a light source unit comprising at least one light source. The Light source may be a Light Emitting Diode (LED), a Laser Diode (LD), an Edge Emitting Laser (EEL), a Vertical Cavity Surface Emitting Laser (VCSEL), or the like. The number of the light sources included in the light source unit can be set according to actual needs, and the light source unit can be a one-dimensional or two-dimensional light source array composed of at least two light sources. The light source array may be a vertical cavity surface emitting laser array chip formed by generating a plurality of vertical cavity surface emitting lasers on a single semiconductor substrate, and the arrangement of the light sources in the light source array may be regular or irregular. The pulsed light beam emitted by the light source may be visible light, infrared light, ultraviolet light, or the like. The emitter can only emit pulse beams with one wavelength to the target, and can also emit pulse beams with at least two wavelengths to the target, and the number of the wavelengths of the pulse beams can be set according to actual needs. When the emitter can emit the pulse beams of at least two wavelengths toward the target, the light emitting unit includes at least two light sources, and the number of the light sources for emitting the pulse beams of each wavelength is at least one.
In application, the pixel unit comprises a plurality of sensing areas. The pixel unit may be a pixel array composed of a plurality of sensing regions, each of the sensing regions may be a Single Photon Avalanche photodiode (SPAD), the Single Photon Avalanche photodiode may respond to an incident Single Photon and output a signal indicating a Time when the Photon reaches the Single Photon Avalanche photodiode, and the collection of the weak light signal and the calculation of the first flight Time may be implemented by using a Time-Correlated Single Photon Counting method (TCSPC), for example. Each sensing region has a function of collecting photons in a light spot projected to a surface thereof and outputting a photon signal.
In application, the grating and the pixel unit are arranged at a preset distance. The preset distance and the diffraction order of the grating can be set according to actual needs, the number of the light spots projected to the pixel unit after the pulse light beam of each wavelength reflected by the target is diffracted by the grating is equal to 2 times plus 1 of the diffraction order of the grating, preferably, the diffraction order of the grating is selected to be 1, and then the number of the light spots projected to the pixel unit after the pulse light beam of each wavelength reflected by the target is diffracted by the grating is 1 × 2+1 — 3, that is, the light spots projected to the pixel unit after the pulse light beam of each wavelength reflected by the target is diffracted by the light beam all include 0-order light spots, -1-order light spots and 1-order light spots. Because the light energy of the-1 order light spot and the 1 order light spot is strongest, the light energy of the diffraction light spot is gradually reduced along with the increase of the diffraction orders, and therefore, the light spots of other orders can be ignored. The light spots projected to the pixel units after the pulse light beams with all wavelengths reflected by the target are diffracted by the grating are all positioned in the same row or the same column.
In one embodiment, the emitter is configured to emit a pulsed light beam of one wavelength toward the target;
the method comprises the steps that a pulse light beam with one wavelength reflected by a target is diffracted by a grating to form x light spots on the surface of a pixel unit;
where x is equal to 2 times the number of diffraction orders m of the grating plus 1.
Fig. 2 schematically shows a first schematic view of a pixel unit and a light spot; the pixel unit 21 is a pixel array composed of 8 × 8 sensing regions, and 3 light spots, namely a 0-order light spot, a-1-order light spot and a 1-order light spot, are formed on the surface of the pixel unit 21 after a pulse light beam with a single wavelength is diffracted by a grating.
In one embodiment, the emitter is used for emitting pulsed beams of y wavelengths to the target;
pulse beams with y wavelengths reflected by the target are diffracted by the grating and then form k light spots on the surface of the pixel unit;
wherein k is greater than or equal to 2 times the diffraction order m of the grating plus 1, and k is less than or equal to 2y times the diffraction order m of the grating plus 1.
In application, due to size limitation of the system, when the transmitter transmits pulsed light beams with at least two wavelengths to a target, the light spots projected to the pixel unit may overlap in orders other than 0 order, so that the total number of light spots projected to the pixel unit after the pulsed light beams with at least two wavelengths are diffracted by the grating is greater than or equal to 2 times of the highest diffraction order m of the grating plus 1, and is less than or equal to 2y times of the highest diffraction order m of the grating plus 1, wherein the 0-order light spots projected to the pixel unit after the pulsed light beams with each wavelength are diffracted by the grating coincide.
Fig. 3 schematically shows a second schematic view of a pixel cell and a light spot; the pixel unit 21 is a pixel array composed of 8 × 8 sensing regions, 5 light spots are formed on the surface of the pixel unit 21 after the pulse light beams with two wavelengths are diffracted by the grating, that is, a 0-order light spot, -1-order light spot and a 1-order light spot corresponding to the pulse light beam with the first wavelength, and a 0-order light spot, -1-order light spot and a 1-order light spot corresponding to the pulse light beam with the second wavelength are superposed with the 0-order light spot corresponding to the pulse light beams with the two wavelengths, and different filling patterns are used for distinguishing and displaying the light spots corresponding to the pulse light beams with different wavelengths.
In application, in order to avoid the situation that the light spots of the pulse light beams with at least two wavelengths are projected to the pixel unit after being diffracted by the grating and the light spots of other orders except for 0 order are overlapped, the spacing distance between the grating and the pixel unit needs to be reasonably set.
In one embodiment, the two wavelengths are each λ1、λ2The pulse light beams are diffracted by the grating and then projected to the pixel unit to respectively form 0-level light spots, -1-level light spots and 1-level light spots corresponding to the pulse light beams with each wavelength, the 0-level light spots corresponding to the pulse light beams with two wavelengths are overlapped to form 5 light spots, and in order to ensure that + 1-level or-1-level light spots except for 0 level are not overlapped, the preset distance needs to satisfy the following relational expression:
wherein h represents the preset distance, r (λ)1) Denotes the wavelength λ1The radius r (lambda) of a-1 or 1-order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating2) Denotes the wavelength λ2The radius theta of a-1-order or 1-order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating1Represents said wavelength as λ1Pulsed light beam ofThe diffraction angle theta of-1 order or 1 order light spot formed on the surface of the pixel unit after diffraction by the grating2Represents said wavelength as λ2The diffraction angle of a-1 or 1 order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating.
In application, when the emitter emits two kinds of pulse beams with different wavelengths to the target, the preset distance may be set by the above relation. For the case that the emitter emits pulsed light beams with two or more wavelengths to the target, the preset distance may also be set in the following manner: emitting pulse beams with y wavelengths to a target through an emitter, continuously adjusting the spacing distance between a grating and a pixel unit, obtaining the number of light spots formed on the surface of the pixel unit after the pulse beams with the y wavelengths reflected by the target are diffracted by the grating, determining that the light spots with orders other than 0 order are not overlapped when the number of the light spots is equal to 2y times plus 1 of the diffraction order m of the grating, calibrating the y wavelengths and the spacing distance between the grating and the pixel unit at the moment, establishing and recording the association relationship between the y wavelengths and the spacing distance, conveniently obtaining the associated spacing distance according to the wavelength of the pulse beams emitted by the emitter during subsequent ranging, setting the preset distance to be greater than or equal to the spacing distance, and enabling the pulse beams with the y wavelengths reflected by the target to be diffracted by the grating to be in the light spots formed on the surface of the pixel unit, the spots of the orders other than 0 order do not overlap.
FIG. 4 is a schematic diagram illustrating an exemplary structure of a collector; wherein, a preset distance h is arranged between the pixel unit 21 and the grating 22, and the wavelength is λ1The diffraction angle of-1 order or 1 order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating is theta1Wavelength of λ2The diffraction angle of a-1 order or 1 order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating is theta2Different dashed arrows indicate diffracted beams corresponding to different wavelengths of the pulsed beam.
In one embodiment, the pulse light beams reflected by the target form a plurality of light spots on the surfaces of n sensing areas in the plurality of sensing areas after being diffracted by the grating;
the processing circuit is used for calculating n first flight times of the pulse light beam according to n photon signals output by the n sensing areas and performing curve fitting on the n first flight times to obtain second flight time of the pulse light beam;
wherein n is less than or equal to the total number of the plurality of sensing regions.
In application, the pulse light beam reflected by the target may form a plurality of light spots only on the surface of a part of the sensing area of the pixel unit after being diffracted by the grating, so that when the first time-of-flight calculation is performed, the processing circuit may calculate the first time-of-flight only according to the photon signals output by the part of the sensing area covered by the light spots, and then perform curve fitting according to the first time-of-flight to obtain the second time-of-flight. Specifically, the positions of the sensing areas where the pulse beams with different wavelengths are projected to the light spots of the pixel units after being diffracted by the grating can be obtained in advance, the association relationship between the pulse beams with different wavelengths and the sensing areas corresponding to the positions is established and recorded, so that when the subsequent distance measurement is performed by emitting the pulse beams with any wavelength to a target through the emitter, the sensing areas which are associated with the pulse beams with the wavelengths can be triggered to collect the light spots and output photon signals.
In one embodiment, the expression for curve fitting the n first times of flight is as follows:
wherein i is 1,2, …, n, i represents the ith sensing region of the n sensing regions,
representing a second time of flight, t, of the pulsed light beamiRepresenting a first time of flight of the pulsed light beam calculated from the photon signal output by the ith sensing region.
In one embodiment, when
When the utility model is used, the water is discharged,
in application, the curve fitting method can specifically adopt a least square method,
the method is equivalent to the method of taking the average value of n first flight times of the pulse light beam obtained by calculating according to photon signals output by n sensing areas, and belongs to the technical field of curve fitting by adopting a least square method and making
Special case results were obtained.
In application, the processing circuit includes a Time-to-Digital Converter (TDC) circuit and a histogram circuit connected to the pixel unit, and may further include a signal amplifier, an Analog-to-Digital Converter (ADC) and other devices. These devices may be integrated with the pixel cell or may be part of the processing circuitry. The TDC circuit is used for calculating a first flight time of the pulse beam, namely a time difference between the receiving time and the transmitting time according to the receiving time of the received photon signal and the transmitting time of the pulse beam transmitted to the target by the transmitter, converting the first flight time into a time code and storing the time code in a histogram circuit connected with the time code, wherein the time code can be a temperature code or a binary code. The histogram circuit is used for drawing the saved time code into a histogram which can represent the waveform of the pulse light beam reflected by the target. The Processing Circuit may be a Central Processing Unit (CPU), other general purpose Processor, a System-on-a-Chip (SOC), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, a discrete Gate or transistor logic device, a discrete hardware Array, or the like. A general purpose processor may be a microprocessor or any conventional processor or the like.
In one embodiment, the processing circuit comprises a plurality of TDC circuits and a plurality of histogram circuits, each sensing region being connected to one of said TDC circuits and each TDC circuit being connected to one of said histogram circuits.
In an application, the processing circuit may comprise the same number of TDC circuits and histogram circuits as the number of sensing regions. Because the light spots projected to the pixel units after the pulse light beams with all wavelengths reflected by the target are diffracted by the grating are positioned in the same row or the same column, each column or each row of sensing areas can be connected with one TDC circuit, and each TDC circuit is connected with one histogram circuit, so that the number of the TDC circuits and the histogram circuits is reduced, and the coefficient structure is simplified; when the light spots are located in the same column, each row sensing area is connected with a TDC circuit. All TDC circuits included in the processing circuit can form an array circuit, and all histogram circuits included in the processing circuit can also form an array circuit. The time resolution of the TDC circuit affects the measurement accuracy of the distance measurement system, and the more the number of bits of the time code output by the TDC circuit is, the higher the memory requirement for the histogram circuit connected thereto is. In order to reduce the data storage amount, reduce the consumption of the storage space of the histogram circuit, and save the cost, the time width and the time resolution of each TDC circuit need to be set reasonably.
Fig. 5 schematically shows a structure of a pixel unit and a processing circuit; the pixel unit 21 is a pixel array composed of 8 × 8 sensing regions, 3 light spots projected to the pixel unit 21 after a pulse light beam with a single wavelength is diffracted by a grating are located in the same column, each row of sensing regions is connected with one TDC circuit 31, and each TDC circuit 31 is connected with one histogram circuit 32.
The embodiment of the present application further provides a distance measurement method implemented based on the distance measurement system provided in the above embodiment, including the following steps implemented by the processing circuit:
controlling the transmitter to transmit a pulse beam to the target;
controlling a pixel unit to collect a plurality of light spots formed on the surface of the pixel unit after the pulse light beam reflected by the target is diffracted by the grating;
and calculating a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit, and performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam.
In an application, the distance measuring method may be performed by the processing circuit when running a computer program stored in the processing circuit or in the memory.
In application, the memory may in some embodiments be an internal storage unit of the processing circuit, such as a memory of the processing circuit. The memory may also be an external storage device to the processing circuit in other embodiments, such as a plug-in hard drive provided on the system, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and so forth. Further, the memory may also include both internal storage units of the processing circuit and external storage devices. The memory is used for storing an operating system, an application program, a Boot Loader (Boot Loader), data, and other programs, such as program codes of computer programs. The memory may also be used to temporarily store data that has been output or is to be output.
An embodiment of the present application further provides a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processing circuit, the steps in the above distance measurement method embodiment are implemented.
Embodiments of the present application provide a computer program product, which when run on processing circuitry, causes the processing circuitry to perform the steps in the above-described distance measurement method embodiments.
The distance measuring system provided by the embodiment of the application comprises a transmitter, a collector and a processing circuit connected with the transmitter and the collector; a transmitter for transmitting a pulsed light beam to a target; the collector comprises a pixel unit and a grating, the pixel unit comprises a plurality of sensing areas, a preset distance is formed between the grating and the pixel unit, a plurality of light spots are formed on the surface of the pixel unit after pulse light beams reflected by a target are diffracted by the grating, and the sensing areas are used for collecting photons in the light spots and outputting photon signals; the processing circuit is used for calculating a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit, performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam, performing independent, multiple and simultaneous acquisition by dispersing the pulse light beam into a plurality of independent light spots and projecting the light spots to different sensing areas to obtain a plurality of photon signals, calculating a plurality of first flight times, and performing curve fitting on the plurality of first flight times to obtain a second flight time, so that the precision of the distance obtained based on the second flight time measurement can be effectively improved.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.
Claims (10)
1. A distance measuring system is characterized by comprising a transmitter, a collector and a processing circuit connected with the transmitter and the collector;
the transmitter is used for transmitting a pulse light beam to a target;
the collector comprises a pixel unit and a grating, the pixel unit comprises a plurality of sensing areas, a preset distance is formed between the grating and the pixel unit, a plurality of light spots are formed on the surface of the pixel unit after pulse light beams reflected by a target are diffracted by the grating, and the sensing areas are used for collecting photons in the light spots and outputting photon signals;
and the processing circuit is used for calculating a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit and performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam.
2. The distance measuring system of claim 1 wherein said transmitter is adapted to transmit a pulsed beam of one wavelength to said target;
the pulse light beam with one wavelength reflected by the target is diffracted by the grating to form x light spots on the surface of the pixel unit;
wherein x is equal to 2 times the diffraction order m of the grating plus 1.
3. The distance measurement system of claim 1 wherein said transmitter is adapted to transmit pulsed beams of y wavelengths to said target;
the pulse beams with y wavelengths reflected by the target are diffracted by the grating to form k light spots on the surface of the pixel unit;
wherein k is greater than or equal to 2 times the diffraction order m of the grating plus 1, and k is less than or equal to 2y times the diffraction order m of the grating plus 1.
4. The distance measurement system of claim 3 wherein said transmitter is adapted to transmit pulsed light beams of two wavelengths to said target;
the pulse beams with two wavelengths reflected by the target are diffracted by the grating to form 5 light spots on the surface of the pixel unit;
the 5 light spots comprise 0-level light spots, 1-level light spots and 1-level light spots corresponding to the pulse light beams with each wavelength, the 0-level light spots corresponding to the pulse light beams with the two wavelengths are overlapped, the 1-level light spots and the 1-level light spots are not overlapped, and the preset distance satisfies the following relational expression:
wherein h represents the preset distance, r (λ)1) Denotes the wavelength λ1The radius r (lambda) of a-1 or 1-order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating2) Denotes the wavelength λ2The radius theta of a-1-order or 1-order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating1Represents said wavelength as λ1The diffraction angle theta of a-1 order or 1 order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating2Represents said wavelength as λ2The diffraction angle of a-1 or 1 order light spot formed on the surface of the pixel unit after the pulse light beam is diffracted by the grating.
5. The distance measurement system of any one of claims 1 to 4, wherein the pulsed light beam reflected by the target forms a plurality of light spots on the surface of n sensing regions of the plurality of sensing regions after being diffracted by the grating;
the processing circuit is used for calculating n first flight times of the pulse light beam according to n photon signals output by the n sensing regions, and performing curve fitting on the n first flight times to obtain a second flight time of the pulse light beam;
wherein n is less than or equal to a total number of the plurality of sensing regions.
6. The distance measurement system of claim 5 wherein said processing circuit comprises a plurality of TDC circuits and a plurality of histogram circuits, each said sensing region being connected to one said TDC circuit, each said TDC circuit being connected to one said histogram circuit.
7. The distance measurement system of claim 5 wherein said curve fitting said n first times of flight is expressed as follows:
wherein i is 1,2, …, n, i represents the ith sensing region of the n sensing regions,
representing a second time of flight, t, of said pulsed light beamiRepresenting a first time of flight of the pulsed light beam calculated from the photon signal output by the ith sensing region.
8. The distance measuring system of claim 7 wherein
When the temperature of the water is higher than the set temperature,
9. a distance measurement method implemented on the basis of the distance measurement system according to any one of claims 1 to 8, comprising the following steps implemented by a processing circuit:
controlling the transmitter to transmit a pulse beam to the target;
controlling a pixel unit to collect a plurality of light spots formed on the surface of the pixel unit after the pulse light beam reflected by the target is diffracted by the grating;
and calculating a plurality of first flight times of the pulse light beam according to a plurality of photon signals output by the pixel unit, and performing curve fitting on the plurality of first flight times to obtain a second flight time of the pulse light beam.
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processing circuit, carries out the steps of the distance measuring method according to claim 9.
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