CN111856485B - Distance measuring system and measuring method - Google Patents
Distance measuring system and measuring method Download PDFInfo
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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
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
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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
- G01S7/495—Counter-measures or counter-counter-measures using electronic or electro-optical means
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Abstract
The invention discloses a distance measuring system, comprising: a transmitter configured to transmit a burst of optical signal pulses having a time encoding; a collector configured to collect photons in the reflected optical signal pulse train; the control and processing circuit is connected with the emitter and the collector, synchronizes trigger signals of the emitter and the collector, generates timing signals synchronous with the trigger signals to regulate and control the timing of the TDC circuit, and records the incident time of photons to form a frame period single photon counting time sequence string; the control and processing circuit controls the emission time of the optical signal pulse train to have dislocation time relative to the timing signal, and a histogram is drawn based on the frame period single photon counting time sequence train to determine the flight time. The invention ensures that all pulse strings in a single frame period can be received and have no pulse response in an adjacent frame period, improves the anti-interference capability of the system, and can effectively solve the pile-up phenomenon by adjusting and controlling the staggered emission of optical pulses relative to timing signals after the timing is started.
Description
Technical Field
The invention relates to the technical field of optical measurement, in particular to a distance measuring system and a distance measuring method.
Background
Distance measurement can be performed on a target using a Time of Flight (TOF) principle to obtain a depth image including a depth value of the target, and a distance measurement system based on the Time of Flight principle has been widely used in the fields of consumer electronics, unmanned driving, AR/VR, and the like. A distance measuring system based on the time-of-flight principle generally includes an emitter and a collector, the emitter emitting a pulsed light beam to illuminate a target field of view and the collector collecting a reflected light beam reflected back by an object in the target field of view, and the collector calculating the time required for the light beam to be received from emission to reflection to calculate the distance to the target object.
In current distance measuring systems based on the time-of-flight principle, the collector comprises a pixel array, in particular a pixel array comprising single photon avalanche photodiodes (SPADs), when a photon in the emitted light beam is incident on the SPAD, an avalanche event output signal can be triggered to record the time of the photon reaching the SPAD, and the time required by the light beam from emission to reception is calculated based on the avalanche event output signal. However, after receiving a photon, the SPAD needs to wait for dead time (dead time) and then receive the next photon, when the target to be detected is closer to the SPAD array or has high reflectivity, the photons in the front part of the reflected beam are more quickly incident into the SPAD array to saturate a plurality of SPADs, and the probability that the subsequently incident photons are collected by the SPADs is reduced, so that the pulse peak position is advanced. Or, under the strong ambient light condition, a large amount of ambient photons are incident into the SPAD array to saturate a plurality of SPADs, and then the probability that signal photons are collected by the SPADs is reduced, so that the formed received waveform is distorted, and accurate flight time cannot be obtained.
The above background disclosure is only for the purpose of assisting understanding of the inventive concept and technical solutions of the present invention, and does not necessarily belong to the prior art of the present patent application, and should not be used for evaluating the novelty and inventive step of the present application in the case that there is no clear evidence that the above content is disclosed at the filing date of the present patent application.
Disclosure of Invention
The present invention is directed to a distance measuring system and a distance measuring method to solve at least one of the above problems.
In order to achieve the above purpose, the technical solution of the embodiment of the present invention is realized as follows:
a distance measurement system comprising:
a transmitter configured to transmit a burst of optical signal pulses having a time encoding;
a collector configured to collect photons in the optical signal pulse train reflected back by an object;
the control and processing circuit is connected with the emitter and the collector, synchronizes trigger signals of the emitter and the collector, generates a timing signal synchronized with the trigger signal to regulate and control the timing of the TDC circuit, and records the incidence time of the photons to form a frame period single photon counting time sequence string;
the control and processing circuit controls the emission time of the optical signal pulse train to have dislocation time relative to the timing signal, and draws a histogram based on the frame period single photon counting time sequence train so as to determine the flight time.
In some embodiments, the misalignment time is random and follows a gaussian distribution whose standard deviation is configured as a random number of pulse widths of the light pulses.
In some embodiments, the transmitter is configured as an array of light sources consisting of a plurality of light sources, each light source in the array of light sources emitting bursts of light signals having different time-encodings.
In some embodiments, the control and processing circuitry performs a convolution calculation cross-correlation with the plotted histogram based on a pre-stored time-code based filter kernel to determine a pulse peak position and determines a time of flight from the pulse peak position; or, based on the time coding mode of the optical signal pulse, drawing a histogram in a time coding continuous single photon counting and stacking mode, and determining the flight time according to the pulse peak value in the histogram.
In some embodiments, the transmitter transmits a burst of optical signal pulses having a dual random or pseudo-random time code, the transmitted pulses being divided into a plurality of groups of pulses, each group of pulses including a plurality of pulses therein, the groups of pulses being transmitted in a first random time code; the groups of pulses are transmitted with a second random time code therebetween.
In some embodiments, the control and processing circuitry controls the transmitter to have a misalignment time of the relative timing signal when transmitting each set of light pulses, the misalignment time being in an encoding mode.
The other technical scheme of the embodiment of the invention is as follows:
a distance measuring method comprising the steps of:
s40, controlling the transmitter to transmit the optical signal pulse train with time coding;
s41, controlling the collector to collect photons in the optical signal pulse train reflected back by the object;
s42, generating a timing signal through a control and processing circuit to regulate and control the timing of the TDC circuit, and recording the incident time of the photons to form a frame period single photon counting time sequence string;
the control and processing circuit controls the emission time of the optical signal pulse train to have dislocation time relative to the timing signal, and draws a histogram based on the frame period single photon counting time sequence train so as to determine the flight time.
In some embodiments, the misalignment times are random and follow a gaussian distribution, the standard deviation of which is configured as a random number of pulse widths of the light pulses.
In some embodiments, the transmitter transmits a burst of optical signal pulses having a dual random or pseudo-random time code, the transmitted pulses being divided into a plurality of groups of pulses, each group of pulses including a plurality of pulses therein, the groups of pulses being transmitted in a first random time code; the groups of pulses are transmitted with a second random time code therebetween.
In some embodiments, further comprising the step of: pre-storing a time-coding-based filter kernel, the control and processing circuit performing convolution calculation cross-correlation with the drawn histogram based on the filter kernel to determine a pulse peak position, and determining a flight time according to the pulse peak position; or the control and processing circuit draws a histogram in a time coding continuous single photon counting superposition mode based on the time coding mode of the optical signal pulse, and determines the flight time according to the pulse peak value in the histogram.
The technical scheme of the invention has the beneficial effects that:
compared with the prior art, the embodiment of the invention ensures that all pulse strings in a single frame period can be received and no pulse response exists in an adjacent frame period, improves the anti-interference capability of the system, and can effectively solve the pile-up phenomenon by adjusting and controlling the staggered emission of the optical pulse relative to the timing signal after the timing is started.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic diagram of a distance measurement system according to one embodiment of the present invention.
FIG. 2 is a schematic diagram of a staggered transmit time-coded pulse modulation scheme for a distance measurement system according to one embodiment of the present invention.
FIG. 3 is a schematic diagram of another staggered transmit time-coded pulse modulation scheme for a distance measurement system according to one embodiment of the present invention.
Fig. 4 is a flowchart illustration of a distance measurement method according to another embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the embodiments of the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element. The connection may be for fixation or for circuit connection.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing the embodiments of the present invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be in any way limiting of the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present invention, "a plurality" means two or more unless specifically limited otherwise.
Fig. 1 is a schematic diagram of a distance measuring system 10 according to an embodiment of the present invention, which includes a transmitter 11, a collector 12, and a control and processing circuit 13. Wherein, the emitter 11 is used to emit a light beam 30 to the target area 20, the light beam is emitted to the target area space to illuminate the target object in the space, at least part of the emitted light beam 30 is reflected by the target area 20 to form a reflected light beam 40, at least part of the reflected light beam 40 is received by the collector 12, the control and processing circuit 13 is respectively connected with the emitter 11 and the collector 12, the trigger signals of the emitter 11 and the collector 12 are synchronized to calculate the time required by the light beam from emission to reception, i.e. the flight time t between the emitted light beam 30 and the reflected light beam 40, further, the distance D of the corresponding point on the target object can be calculated by the following formula:
D＝c·t/2 (1)
where c is the speed of light.
The transmitter 11 includes a light source 111, a transmitting optical element 112, a driver 113, and the like. The light source 111 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, or may be a one-dimensional or two-dimensional light source array composed of a plurality of light sources; preferably, the light source array is a VCSEL array light source chip formed by generating a plurality of VCSEL light sources on a single semiconductor substrate, and the arrangement of the light sources in the light source array may be regular or irregular. The light beam emitted by the light source 111 may be visible light, infrared light, ultraviolet light, or the like. The light source 111 emits a light beam outward under the control of the driver 113. In one embodiment, the light source 111 emits a pulsed light beam outward under the control of the driver 113 at a frequency (pulse period) that can be used in Direct time of flight (Direct TOF) measurements, the frequency being set according to the measurement distance. It will be appreciated that the light beam emitted by the light source 111 may also be controlled by means of a part of the control and processing circuit 13 or a sub-circuit present independently of the control and processing circuit 13.
The emission optical element 112 receives the light beam emitted from the light source 111 and projects the light beam to a target region after shaping. In one embodiment, the transmitting optical element 112 receives the pulsed light beam from the light source 111 and optically modulates, such as diffracting, refracting, reflecting, etc., the pulsed light beam, and then transmits the modulated light beam, such as a focused light beam, a flood light beam, a structured light beam, etc., into space. The emitting optical elements 112 may be in the form of one or more combinations of lenses, liquid crystal elements, diffractive optical elements, microlens arrays, Metasurface (Metasurface) optical elements, masks, mirrors, MEMS mirrors, and the like.
And the control and processing circuit 13 synchronizes the trigger signals of the emitter 11 and the collector 12, processes the photon signals of the pixel collected light beams, and calculates the distance information of the target to be measured based on the flight time of the reflected light beams. In one embodiment, the SPAD outputs a photon signal in response to an incident single photon, and the control and processing circuitry 13 receives the photon signal and performs signal processing to obtain the time of flight of the beam. In particular, the control and processing circuit 13 calculates the number of photons collected to form successive time bins, which are joined together to form a statistical histogram for reconstructing the time series of the reflected beam, and identifies the time of flight of the reflected beam from emission to reception using peak matching and filtering detection. In some embodiments, the control and processing circuitry 13 includes readout circuitry (not shown) comprising one or more of signal amplifiers, time-to-digital converters (TDCs), digital-to-analog converters (ADCs), and the like. These circuits may be integrated with the pixels or may be part of the control and processing circuit 13, and for convenience of description, they will be collectively considered as part of the control and processing circuit 13. It will be appreciated that the control and processing circuitry 13 may be separate dedicated circuitry, such as a dedicated SOC chip, FPGA chip, ASIC chip, etc., or may comprise general purpose processing circuitry.
In some embodiments, the distance measurement system 10 further includes a memory for storing a pulse code program with which to control the excitation time, emission frequency, etc. of the light beam emitted by the light source 111.
In some embodiments, the distance measurement system 10 may further include a color camera, an infrared camera, an IMU, etc., and a combination thereof may implement more rich functions, such as 3D texture modeling, infrared face recognition, SLAM, etc.
In some embodiments, emitter 11 and collector 12 may be arranged coaxially, i.e. they are implemented by an optical device with reflection and transmission functions, such as a half-mirror.
FIG. 2 is a schematic diagram of time-coded pulse modulation transmitted by a distance measuring system in a staggered manner according to an embodiment of the present invention. In one embodiment, the control and processing circuit 13 includes a TDC circuit and a histogram circuit for plotting a histogram reflecting the waveform of the pulses emitted by the light source in the emitter, and further, calculating the time of flight from the histogram, and finally outputting the result.
A receive waveform is plotted in a histogram circuit that reflects the waveform of the pulse emitted by the light source in the emitter, typically substantially similar in shape to the emitted pulse waveform, the receive waveform representing the number of photons in the reflected pulse incident in the pixel array. However, since the SPAD array enters dead time after receiving photons and no longer detects photons, it is easy to cause the resulting distortion of the received waveform to generate a pile-up phenomenon, and it will be described below through some embodiments if this problem is solved, so as to improve the accuracy of the distance measurement system.
In particular, the transmitter 21 is configured to transmit bursts of optical signals having a temporal coding towards the target area, wherein the temporal coding may be a regular temporal coding or a random temporal coding; the time coding may be single time coding or double time coding (the used time coding technology may refer to the related content in chinese patent application publication No. cn201910814078.x, which is not described in detail in the embodiments of the present invention). Collector 22 is configured to collect a portion of the photons in the optical signal pulse train reflected back from the target, TDC circuitry processes and records the respective time of incidence of each incident photon to form a frame-period single photon count time sequence train; the histogram circuit draws a histogram based on the frame period single photon counting time sequence string; the control and processing circuitry is adapted to determine the pulse peak positions of the pulse waveforms in the histogram and to determine the time of flight based on the pulse peak positions. The control and processing circuit 13 synchronizes the trigger signals of the emitter 21 and the collector 22 to calculate the time required by the light beam from emission to reception, and generates a timing signal synchronized with the trigger signal to regulate the TDC circuit to start timing for recording the time taken by the photons in the pulsed light beam from emission to reception.
The control and processing circuit 13 controls the transmitter 21 to, upon receipt of the trigger signal, misalign the burst of optical signals with respect to the timing signal, i.e. the transmission time of the burst of optical signals is misaligned with respect to the timing signal. Wherein the skew time is random (pseudo-random) and follows a gaussian distribution, the standard deviation of which is configured as a random number of the pulse width of the light pulse. The optical pulse presents Gaussian distribution in time, when the collector receives a large number of photons in front of the pulse, the waveform of the histogram drawn in the histogram circuit is too narrow to meet the Gaussian distribution, and the peak positioning cannot be accurately carried out. Therefore, in the embodiment of the invention, the staggered emission of the light pulse relative to the timing signal is regulated and controlled after the timing is started, and the staggered time is set to obey Gaussian distribution so as to ensure that a histogram meeting the Gaussian distribution can be drawn when a large number of photons in the front of the light pulse are received in the histogram circuit, thereby performing peak positioning and effectively solving the pile-up phenomenon.
In one embodiment, as shown in FIG. 2, transmitter 21 transmits bursts of optical signals having a random (pseudo-random) time code of [ Δ t [1，Δt1+Δt2，Δt1+Δt2+Δt3，…，Δt1+Δt2…+Δt(n-1)]Wherein, Δ tiThe time interval between the ith pulse and the (i +1) th pulse is represented, i being 1,2, … (n-1). If the measured target is at D and the corresponding time of flight is t, then collector 22 will subsequently receive photons in the pulse train reflected by the target after time t. In order to ensure that the mutual influence of the pulsed light beams in two adjacent frame periods is avoided, the frame period T is set to
I.e. when the maximum target is at the maximum measurement distance, the time required for the last pulse in the pulse train from the start of transmission by transmitter 21 until the end of reception by collector 22 is exactly t1This ensures that all bursts in a single frame period are received and there is no impulse response in an adjacent frame period. By configuring and transmitting the optical signal pulse train with time coding, the frame rate is effectively improved, and meanwhile, the anti-interference capability of the distance measurement system can be improved. And the control and processing circuit 13 controls the time of the train of light signal pulses emitted by the emitter 21 to be offset by a time R with respect to the timing signal1To collectThe device starts to collect reflected photons after receiving the trigger signal, the timing signal of the synchronous trigger signal controls the TDC circuit to start timing, and the time from emission to reception of the photons in the optical pulse is recorded, so that the photons in the reflected optical pulse can be detected.
In one embodiment, the time-code based filter kernel is pre-stored, and the control and processing circuitry 13 performs a convolution calculation cross-correlation based on the filter kernel and a histogram plotted in the histogram circuitry to determine the pulse peak position, and from the pulse peak position, the time of flight is determined.
In one embodiment, the histogram circuit is used for drawing the histogram in a time coding continuous single photon counting superposition mode according to a time coding mode of the emitted optical signal pulse, namely taking the current to-be-drawn histogram as an initial unit, superposing the photon counting values of corresponding time units in the time sequence string according to the time coding, and counting the superposed photons as the photon counting values of the initial time units. For example, the time code of the emitted light signal pulse train is [ Δ t ]1，Δt1+Δt2，Δt1+Δt2+Δt3，…，Δt1+Δt2…+Δt(n-1)]Then, the time unit to be drawn is used as the starting unit, and the interval between the time sequence string and the starting unit is delta t1，Δt1+Δt2，Δt1+Δt2+Δt3，…，Δt1+Δt2…+Δt(n-1)The photon counting values of all time units are sequentially superposed with the initial photon counting value, and the superposed photon counting is used as the numerical value of the time unit in the histogram. The position of the pulse peak in the histogram is determined and the time of flight is determined from the pulse peak position.
Fig. 3 is a schematic diagram of staggered emission time-coded pulse modulation according to another embodiment of the present invention. As shown in fig. 3, the transmitter 31 transmits optical signal pulse train with double random (pseudo random) time coding (the time coding technique can be referred to the related content in chinese patent application publication No. CN 201910814076.0), the transmitted pulses are divided into a plurality of pulse groups, each pulse group contains a plurality of pulses, and each pulse group contains a plurality of pulsesBurst is encoded with a first random time [ Δ t ]1，Δt1+Δt2，Δt1+Δt2+Δt3，…，Δt1+Δt2…+Δt(n-1)]Is transmitted in the form of, wherein, atiRepresents the time interval between the ith pulse and the (i +1) th pulse, i being 1,2, … (n-1); with a second random time code [ Delta T ] between groups1，ΔT1+ΔT2，ΔT1+ΔT2+ΔT3，…，ΔT1+ΔT2…+ΔT(N-1)]Is transmitted in the form of Δ TjThe time interval between the jth pulse group and the (j +1) th pulse group is represented, j is 1,2, … (N-1), and N represents the number of pulse groups. If the target is at D and the corresponding flight time is T, the collector 32 will receive the photons in the pulse train reflected by the target after T, and the frame period T is set to avoid the mutual influence of the pulse beams in two adjacent frame periods
I.e. when the maximum target is at the maximum measurement distance, the time required for the last pulse in the pulse train from the transmission by the transmitter 31 until the reception by the collector 32 is over is exactly t1This ensures that all bursts in a single frame period are received and there is no impulse response in an adjacent frame period.
In contrast to what is shown in fig. 2, the control and processing circuit 13 controls the transmitter 31 to transmit each set of light pulses with a skew time relative to the timing signal, which skew time is also in the coding mode, i.e. skew time coding R1，R1+R2，R1+R2+R3，…，R1+R2…+RN]N represents the number of pulse groups, RkDenotes the offset time of the kth pulse group with respect to the timing signal, k being 1,2, … N, the offset time being random (pseudo-random), and the offset time R beingkObey gaussThe standard deviation of the distribution, gaussian, is configured as a random number of the pulse width of the light pulse.
In one embodiment, the dual time coding based filter kernel is pre-stored, and the control and processing circuitry 13 performs a convolution calculation cross-correlation based on the filter kernel and a histogram plotted in the histogram circuitry to determine the pulse peak position and from the pulse peak position the time of flight is determined.
In one embodiment, the histogram is plotted in a time-coded superposition and then fused according to the time-coding mode of the emitted light signal pulses. The method comprises the following steps of (1) dividing the pulse group period single photon counting time sequence into two steps for drawing (the two steps are not in sequence), wherein the first step is to stack the photon counting of corresponding time units among N pulse group period single photon counting time sequence strings; and a second step of superposing the total time sequence string obtained in the first step according to the first time code of the transmitted pulse in the pulse group. Determining pulse peak positions in the histogram and determining time of flight based on the pulse peak positions
It can be understood that configuring the transmitter to transmit the optical signal pulse train based on the time code can effectively improve the anti-interference capability of the distance measurement system, but in some embodiments, the transmitter is configured as a light source array composed of a plurality of light sources to transmit a plurality of optical signal pulse trains at the same time, a crosstalk phenomenon may also occur when the light pulses transmitted by adjacent light sources are received by the collector after being reflected by the target, and in order to solve the interference problem caused by the system itself, each light source may be set to transmit the optical signal pulse train with different time codes. Alternatively, in one embodiment, configuring the light sources to emit bursts of optical signals with dual time codes, wherein groups of pulses emit bursts with the same first random time code, and varying the random time code patterns from group to achieve each light source emitting bursts of optical signals with different time codes, may also effectively avoid the occurrence of crosstalk. Meanwhile, the control and processing circuit controls the emitter to regulate the emitting time of the light pulse relative to the timing signal after receiving the trigger signal, so that the problem of pile-up can be solved.
Referring to fig. 4, as another embodiment of the present invention, the present invention further provides a distance measuring method, and fig. 4 is a flowchart of the distance measuring method, where the method includes the following steps:
s40, controlling the transmitter to transmit the optical signal pulse train with time coding;
s41, controlling the collector to collect photons in the optical signal pulse train reflected back by the object;
s42, generating a timing signal through the control and processing circuit to regulate and control the timing of the TDC circuit, and recording the incident time of photons to form a frame period single photon counting time sequence string;
the control and processing circuit controls the emission time of the optical signal pulse train to have dislocation time relative to the timing signal, and a histogram is drawn based on the frame period single photon counting time sequence train to determine the flight time.
In an embodiment of the invention, the misalignment times are random and follow a gaussian distribution, the standard deviation of which is configured as a random number of the pulse width of the light pulse.
In some embodiments, the transmitter transmits a burst of optical signals having a double random or pseudo-random time code, the transmitted pulses being divided into a plurality of groups of pulses, each group of pulses containing a plurality of pulses therein, the groups of pulses being transmitted in a first random time code; the pulse groups are transmitted in a second random time coding mode; wherein the control and processing circuitry controls the transmitter to have a misalignment time of the relative timing signal when transmitting each set of light pulses, wherein the misalignment time is also in a coding mode, the misalignment time is random (pseudo-random), and the misalignment time follows a gaussian distribution, the standard deviation of the gaussian distribution being configured as a random number of pulse widths of the light pulses.
In some embodiments, further comprising the step of: pre-storing a time coding-based filter kernel, and performing convolution calculation cross-correlation on the control and processing circuit and the drawn histogram based on the filter kernel to determine a pulse peak position and determine flight time according to the pulse peak position;
it should be noted that, the distance measurement method of the present embodiment adopts the distance measurement system to perform distance measurement, and the technical solution thereof is the same as that of the distance measurement system, and therefore, the detailed description thereof is not repeated herein.
It can be understood that the invention further provides a scheme for solving the pile-up phenomenon on the basis of effectively solving the interference problem, thereby improving the accuracy of the distance measurement system, enhancing the anti-interference characteristic of the system and effectively improving the frame rate.
The present application also provides a storage medium for storing a computer program that, when executed, performs at least the distance measurement method described in the foregoing embodiments.
The storage medium may be implemented by any type of volatile or non-volatile storage device, or combination thereof. Among them, the nonvolatile Memory may be a Read Only Memory (ROM), a Programmable Read Only Memory (PROM), an erasable Programmable Read-Only Memory (EPROM), an electrically erasable Programmable Read-Only Memory (EEPROM), a magnetic random Access Memory (FRAM), a Flash Memory (Flash Memory), a magnetic surface Memory, an optical Disc, or a Compact Disc Read-Only Memory (CD-ROM); the magnetic surface storage may be disk storage or tape storage. Volatile Memory can be Random Access Memory (RAM), which acts as external cache Memory. By way of illustration and not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Synchronous Static Random Access Memory (SSRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), Double Data rate Synchronous Dynamic Random Access Memory (DDRSDRAM, Double Data rate Synchronous Dynamic Random Access Memory), Enhanced Synchronous Dynamic Random Access Memory (ESDRAM, Enhanced Synchronous Dynamic Random Access Memory), Synchronous link Dynamic Random Access Memory (SLDRAM, Synchronous Dynamic Random Access Memory (DRAM), Direct Memory (DRM, Random Access Memory). The storage media described in connection with the embodiments of the invention are intended to comprise, without being limited to, these and any other suitable types of memory.
The embodiment of the present application further provides a computer device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement at least the distance measurement method in the foregoing embodiment.
It is to be understood that the foregoing is a more detailed description of the invention, and that specific embodiments are not to be considered as limiting the invention. It will be apparent to those skilled in the art that various substitutions and modifications can be made to the described embodiments without departing from the spirit of the invention, and these substitutions and modifications should be considered to fall within the scope of the invention. In the description herein, references to the description of the term "one embodiment," "some embodiments," "preferred embodiments," "an example," "a specific example," or "some examples" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention.
In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. Although embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the invention as defined by the appended claims.
Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. One of ordinary skill in the art will readily appreciate that the above-disclosed, presently existing or later to be developed, processes, machines, manufacture, compositions of matter, means, methods, or steps, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
Claims (8)
1. A distance measuring system, comprising:
a transmitter configured to transmit a burst of optical signal pulses having a time encoding;
a collector configured to collect photons in the optical signal pulse train reflected back by an object;
the control and processing circuit is connected with the emitter and the collector, synchronizes trigger signals of the emitter and the collector, generates a timing signal synchronized with the trigger signal to regulate and control the timing of the TDC circuit, and records the incidence time of the photons to form a frame period single photon counting time sequence string;
the control and processing circuit controls the emission time of the optical signal pulse train to have dislocation time relative to the timing signal, and draws a histogram based on the frame period single photon counting time sequence train to determine the flight time;
the misalignment time is random and follows a gaussian distribution whose standard deviation is configured as a random number of pulse widths of the light pulses.
2. The distance measuring system of claim 1 wherein: the transmitter is configured as an array of light sources consisting of a plurality of light sources, each light source in the array of light sources emitting bursts of light signals having different time-encoding.
3. The distance measuring system of claim 1 wherein: the control and processing circuit performs convolution calculation cross-correlation based on a filter kernel and the drawn histogram to determine a pulse peak position and determines flight time according to the pulse peak position, wherein the filter kernel is a pre-stored filter kernel based on time coding; alternatively, the first and second electrodes may be,
and drawing the histogram in a time coding continuous single photon counting superposition mode based on the time coding mode of the optical signal pulse train, and determining the flight time according to the pulse peak value in the histogram.
4. The distance measuring system of claim 1 wherein: the transmitter transmits a burst of optical signal pulses having a dual random time code, the transmitted pulses being divided into a plurality of groups of pulses, each group of pulses including a plurality of pulses therein, the groups of pulses being transmitted in a first random time code; the groups of pulses are transmitted with a second random time code therebetween.
5. The distance measuring system of claim 4, wherein: the control and processing circuit controls the emitter to have the misalignment time with respect to the timing signal when emitting each set of light pulses, the misalignment time being in an encoding mode.
6. A distance measuring method, characterized by comprising the steps of:
s40, controlling the transmitter to transmit the optical signal pulse train with time coding;
s41, controlling the collector to collect photons in the optical signal pulse train reflected back by the object;
s42, generating a timing signal through a control and processing circuit to regulate and control the timing of the TDC circuit, and recording the incident time of the photons to form a frame period single photon counting time sequence string;
the control and processing circuit controls the emission time of the optical signal pulse train to have dislocation time relative to the timing signal, and draws a histogram based on the frame period single photon counting time sequence train to determine the flight time;
the misalignment time is random and follows a gaussian distribution whose standard deviation is configured as a random number of pulse widths of the light pulses.
7. The distance measuring method according to claim 6, characterized in that: the transmitter transmits a burst of optical signal pulses having a dual random time code, the transmitted pulses being divided into a plurality of groups of pulses, each group of pulses including a plurality of pulses therein, the groups of pulses being transmitted in a first random time code; the groups of pulses are transmitted with a second random time code therebetween.
8. The distance measuring method according to claim 6, further comprising the steps of: pre-storing a filter kernel based on the time code, and performing convolution calculation cross-correlation on the control and processing circuit and the drawn histogram based on the filter kernel to determine a pulse peak position and determine flight time according to the pulse peak position; alternatively, the first and second electrodes may be,
and the control and processing circuit adopts a time coding continuous single photon counting superposition mode to draw the histogram based on the time coding mode of the optical signal pulse train, and determines the flight time according to the pulse peak value in the histogram.
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| CN202010537808.9A CN111856485B (en) | 2020-06-12 | 2020-06-12 | Distance measuring system and measuring method |
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| CN111856485B (en) * | 2020-06-12 | 2022-04-26 | 深圳奥锐达科技有限公司 | Distance measuring system and measuring method |
| CN112034615B (en) * | 2020-08-31 | 2022-06-24 | 同济大学 | Control coding method, device and medium for variable lens for high-speed scanning |
| CN111929662B (en) * | 2020-10-12 | 2020-12-15 | 光梓信息科技（上海）有限公司 | Sensing device |
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| WO2022126582A1 (en) * | 2020-12-18 | 2022-06-23 | 深圳市汇顶科技股份有限公司 | Time-of-flight sensor and related system and method |
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| CN114488174B (en) * | 2022-01-04 | 2024-04-12 | 中国科学院西安光学精密机械研究所 | Ranging system and method based on double-channel single photon detection and two-dimensional cross correlation |
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