CN110456369B - Flight time sensing system and distance measuring method thereof - Google Patents

Flight time sensing system and distance measuring method thereof Download PDF

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CN110456369B
CN110456369B CN201910694911.1A CN201910694911A CN110456369B CN 110456369 B CN110456369 B CN 110456369B CN 201910694911 A CN201910694911 A CN 201910694911A CN 110456369 B CN110456369 B CN 110456369B
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depth value
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initial depth
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CN110456369A (en
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黄勇亮
梅健
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Ruyu Intelligent Technology Suzhou Co ltd
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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
    • 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
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/4865—Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak

Abstract

A flight time sensing system and a distance measuring method thereof are provided, wherein the flight time distance measuring method comprises the following steps: delaying the detection light pulse frame by frame in the order of the plurality of detection frames; receiving reflected light of the detection light pulse after being reflected by the object to be detected, and acquiring a plurality of initial depth values respectively corresponding to each detection frame; according to the distance coefficient corresponding to the initial depth value, selecting one of the initial depth values as an actually measured depth value of an output frame corresponding to the plurality of detection frames, wherein the actually measured depth value is smaller than the initial depth value corresponding to the first detection frame, and the initial depth value is positively correlated with the distance coefficient. The flight time sensing system can weaken the interference of multiple reflected lights and improve the accuracy of distance detection.

Description

Flight time sensing system and distance measuring method thereof
Technical Field
The invention relates to the technical field of sensing, in particular to a flight time sensing system and a distance measuring method thereof.
Background
The Time Of Flight (TOF) method measures the three-dimensional structure or three-dimensional profile Of an object to be measured by using a Time interval between transmission and reception Of a pulse signal from a measuring instrument or a phase difference generated when a laser beam travels back and forth to the object to be measured once. The TOF measuring instrument can simultaneously obtain a gray image and a distance image, and is widely applied to the fields of somatosensory control, behavior analysis, monitoring, automatic driving, artificial intelligence, machine vision, automatic 3D modeling and the like.
Time-of-flight (TOF) sensors generally include: the device comprises a light source module and a photosensitive module; the light source module is used for emitting pulse detection light with a specific waveband and a specific frequency, the detection light is reflected on the surface of a detected object, and the reflected light is received by the photosensitive module; and the photosensitive module calculates the distance information of the object to be measured according to the time difference or the phase difference between the transmitting light wave and the receiving light wave.
However, in the prior art, particularly when the detection environment is relatively complicated, a detection result of the TOF sensor has a large error.
Disclosure of Invention
The invention aims to solve the technical problem of providing a flight time sensing system and a distance measuring method thereof, which can eliminate the problem of multipath interference of light and improve the accuracy of distance detection.
The technical scheme of the invention provides a distance measuring method of a flight time sensing system, which comprises the following steps: delaying the detection light pulse frame by frame in the order of the plurality of detection frames; receiving reflected light of the detection light pulse after being reflected by the object to be detected, and acquiring a plurality of initial depth values respectively corresponding to each detection frame; according to the distance coefficient corresponding to the initial depth value, selecting one of the initial depth values as an actually measured depth value of the output frame corresponding to the plurality of detection frames, wherein the actually measured depth value is smaller than the initial depth value corresponding to the first detection frame, and the initial depth value is positively correlated with the distance coefficient.
Optionally, the detection light pulses are delayed frame by frame at the same time intervals.
Optionally, the time-of-flight sensing system includes a pixel array composed of a plurality of pixel units; respectively acquiring initial depth values of all detection frames aiming at all pixel units; and respectively acquiring the actually measured depth values corresponding to the pixel units.
Optionally, an initial depth value corresponding to the distance coefficient closest to the preset threshold is used as the measured depth value.
Optionally, an initial depth value corresponding to any distance coefficient within a set threshold range is used as the measured depth value.
Optionally, the two shutters are used for sequentially collecting energy of the reflected light, and the distance coefficient corresponding to the initial depth value is a ratio of the reflected light energy collected by the second shutter to the total reflected light energy collected by the two shutters.
Optionally, in a plurality of detection frames corresponding to a single output frame, the maximum delay time of the detection light pulse is smaller than or equal to the pulse width of the detection light pulse.
Optionally, the method further includes: acquiring the delay time of the detection light corresponding to the initial depth value as the actually measured depth value, and taking the delay time as the fixed delay time; and delaying the detection light pulse of each subsequent detection frame by a fixed delay time, and taking the initial depth value of each subsequent detection frame as the actually-measured depth value.
The technical scheme of the invention also provides a flight time sensing system, which comprises: the light source module is used for emitting detection light pulses; the sensing module is used for receiving reflected light of the detection light pulse after being reflected by an object to be detected;
the control module is connected with the light source module and used for controlling the light source module to delay the detection light pulse frame by frame according to the sequence of a plurality of detection frames; the processing module is connected with the sensing module and used for carrying out the following processing: acquiring a plurality of initial depth values respectively corresponding to each detection frame according to the detection light and the reflected light; according to the distance coefficient corresponding to the initial depth value, selecting one of the initial depth values as an actually-measured depth value of the output frame corresponding to the plurality of detection frames, wherein the actually-measured depth value is smaller than the initial depth value corresponding to the first detection frame, and the initial depth value is positively correlated with the distance coefficient.
Optionally, the control module is configured to control the light source module to delay the detection light pulse frame by frame at the same time interval.
Optionally, the time-of-flight sensing system includes a pixel array composed of a plurality of pixel units; the processing module is used for respectively obtaining the initial depth value of each detection frame aiming at each pixel unit and respectively obtaining the actual measurement depth value corresponding to each pixel unit.
Optionally, the processor is configured to obtain the distance coefficient, and use an initial depth value corresponding to the distance coefficient closest to a preset threshold as the actually measured depth value.
Optionally, the processor is configured to obtain the distance coefficient, and use an initial depth value corresponding to any distance coefficient within a set threshold range as the measured depth value.
Optionally, the control module is configured to control the two shutters to sequentially collect energy of the reflected light, and the distance coefficient corresponding to the initial depth value is a ratio of the energy of the reflected light collected by the second shutter to the total energy of the reflected light collected by the two shutters.
Optionally, in a plurality of detection frames corresponding to a single output frame, the maximum delay time of the detection light pulse is smaller than or equal to the pulse width of the detection light pulse.
Optionally, the processing module is further configured to obtain a delay time of the detected light pulse corresponding to the initial depth value as the actually measured depth value, and use the delay time as a fixed delay time; the control module is used for controlling the light source module to delay the detection light pulse of each subsequent detection frame by a fixed delay time; the processing module is used for taking the initial depth value of each subsequent detection frame as the measured depth value.
The distance measuring method eliminates the influence of multiple reflected lights on the detection result by delaying the detection light pulse, and the actually measured depth value is smaller than the initial depth value corresponding to the first detection frame and is closer to the actually measured distance, so that the detection result is corrected, and the accuracy of distance detection is improved.
Drawings
FIG. 1 is a schematic diagram of a reflection path existing during a ranging process according to an embodiment of the present invention;
FIG. 2a is a schematic illustration of the detection of optical pulse delay in the presence of only one reflected light according to an embodiment of the present invention;
FIG. 2b is a schematic illustration of the detection of optical pulse delays in the presence of one and more reflected lights according to an embodiment of the present invention;
FIG. 3 is a flow chart illustrating a ranging process according to an embodiment of the present invention;
FIG. 4 is a diagram illustrating a correspondence relationship between an output frame and a detection frame according to an embodiment of the present invention;
FIG. 5 is a diagram illustrating a correspondence relationship between a plurality of output frames and a detection frame according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a time-of-flight sensing system according to an embodiment of the present invention.
Detailed Description
As described in the background section, the time-of-flight sensor of the prior art has a large detection error in a complicated detection environment.
The inventor researches and discovers that part of detection errors are caused by multiple reflected lights, the multiple reflected lights are transmitted through multiple reflection paths, the optical path is large, and the multiple reflected lights are received in a delayed mode, so that the detection results are inaccurate. The specific description is as follows:
referring to fig. 1(a), in this case, only one reflected light exists, the detection light emitted by the light source module directly reaches the surface of the object to be detected, and when the reflected light reflected by the object to be detected is directly received by the light sensing module, the distance corresponds to the time difference or the phase difference between the emission light wave and the reception light wave.
In the actual measurement process, under the condition that the measurement environment is relatively complex, the problem of multipath interference of light exists. Part of the detection light directly reaches the surface of the object to be detected, and the reflected light is also directly received by the photosensitive module; part of the detecting light may be reflected by the interfering object multiple times and then reach the surface of the object to be detected, and the reflected light reflected by the surface of the object to be detected may also be reflected by the interfering object multiple times and then received by the photosensitive module again (see fig. 1 (b)). In this case, the optical path length of part of the detected light and/or reflected light is greater than twice the distance between the actual light source and the object to be measured, and the time difference or phase difference between the emitted light wave and the received light wave does not correspond to the distance, which results in a decrease in the accuracy of the finally detected distance information.
Further, referring to fig. 2a and fig. 2b, in this embodiment, the pulse of the detecting light is a rectangular pulse. In the process of receiving the reflected light, the reflected light signal (actually including the reflected light of the detected light and the ambient light) is received by the shutters G2 and G3, and the ambient light signal is received by the shutter G1. Specifically, the shutters G1, G2, and G3 may be implemented by a capacitive structure, and after the ambient light and the reflected light are received by the pixel units of the sensor array, the light signals are converted into electrical signals, and charges of the electrical signals are accumulated by the shutters G1, G2, and G3, so that the amount of the obtained charges is proportional to the light energy. The receiving time of the shutters G1, G2, and G3 is T, and is consistent with the pulse width of the detection light pulse, the depth value may be a distance, or an intermediate parameter corresponding to the distance, for example, a ratio of the charge amounts received by the shutters G2 and G3, and the charge amounts may be represented by electrical parameters such as voltage. The edges of the integration pulses of G1, G2 and G3 are aligned in sequence, the falling edge of G1 is aligned with the rising edge of G2, and the falling edge of G2 is aligned with the rising edge of G3.
In the case of no multiple reflection (see fig. 2a), the accumulated charge amount of each shutter, i.e. the light energy received by each shutter, is represented by G1, G2, and G3, respectively. Then when the detect light pulse LO1 is aligned with the shutter G2 pulse, i.e., the delay is 0, both shutters G2 and G3 accumulate partially reflected light energy and the depth values measured for exposure correspond to the following distances:
Figure BDA0002149058880000051
since the ambient light energy collected by the shutters G1, G2, and G3 are all the same, the equation can be simplified to:
Figure BDA0002149058880000052
wherein G2 'and G3' represent reflected light energy of the detection light received by the shutters G2 and G3 after being reflected by the object to be measured. Detecting the obtained depth information and distance coefficient
Figure BDA0002149058880000053
Or
Figure BDA0002149058880000054
And are in positive correlation.
The detection light pulse is difficult to be a standard rectangular pulse because of errors in the light intensity of the detection light and in time control. Therefore, in other embodiments, the detection light pulse may be a triangular wave pulse or a non-standard rectangular wave pulse. At this time, the detected distance is positively correlated with the distance coefficient y.
When the detection light pulse is not moving,
Figure BDA0002149058880000055
detecting the distance d and
Figure BDA0002149058880000056
and (4) positively correlating.
When the pulse is shifted back by Ts,
Figure BDA0002149058880000061
wherein d is0And
Figure BDA0002149058880000062
the relationship of (c) is unchanged.
For the case where there are no multiple reflections, d is the only reflection light that is not moved out of the reception range of the shutter G30Is increased by an amount just equal to
Figure BDA0002149058880000063
Therefore, d does not change either; when the reflected light completely moves out of the receiving range of the shutter G2, the distance coefficient
Figure BDA0002149058880000064
d0No longer increases and thus d decreases linearly with the delay time Ts.
For the case of multipath reflection, referring to fig. 2b, since the optical path of the multiple reflected light is larger than the optical path of the single reflected light, the time to reach the sensor array of the sensor is delayed. The reflected light LB11 corresponding to the detection light pulse LO11 includes first reflected light and multiple reflected light, and the energy of the multiple reflected light is small; the offset Td between the primary reflected light pulse and the detection light pulse is proportional to the actual distance, and the multiple reflected light lags behind the primary reflected light by Tp, which results in the shutter G3 receiving the multiple reflected light for an extra time Tp to obtain more reflected light energy, and according to the formula (2), the larger G3' results in the measured distance being larger than the actual distance.
From the above-described studies, the inventors have further found that by shifting the pulse width of the detection light backward, the reflected light can be shifted backward, and the delay portion of the secondary and multiple reflected lights is gradually out of the range of reception of the integrated pulse of the shutter G3 due to more delay, and cannot be received by the shutter G3, thereby reducing the influence of the delay portion of the secondary and multiple reflected lights on the distance detection. Referring to fig. 2b, when the delay time Ts of the detection light pulse LO12 is Td + Tp, the portion of the secondary reflected light delayed by the time period of the primary reflected light Tp cannot be received by the shutter G3 any more, the distance coefficient is 1, the shutter G3 can only receive the reflected light within T time, and the shutter G2 cannot collect the reflected light energy.
As is apparent from the above analysis, accumulation of the delayed part of the twice or more reflected light by the shutter G3 can be eliminated by delaying the detection light pulse, thereby eliminating the influence of the multiple reflected light on the detection result. And the closer the distance coefficient is to 1, the smaller the influence of the secondary or secondary reflected light on the detection result.
However, in the actual distance measurement process, we cannot know the specific delay time of the multiple reflected light, and therefore cannot accurately set the optimum delay time for detecting the light pulse.
Therefore, the inventor proposes a new time-of-flight sensing system and a ranging method thereof, which use a method of delaying the detection light pulse frame by frame to correct the detection result by gradually moving the detection light pulse backwards for a plurality of times.
The following describes in detail a specific embodiment of a time-of-flight sensing system and a ranging method thereof according to the present invention with reference to the accompanying drawings.
Fig. 3 is a schematic flow chart of a distance measuring method of a time-of-flight sensing system according to an embodiment of the present invention.
The distance measuring method of the flight time sensing system at least comprises the following steps:
step S101: the detection light pulse is delayed frame by frame in the order of the plurality of detection frames.
In this embodiment, the detection data of each output frame is obtained by processing the detection data of a plurality of detection frames, one output frame corresponds to outputting one detection result, and one detection frame corresponds to performing one detection exposure. Referring to FIG. 4, for the first output frame F1Corresponding to n detection frames f11～f1nSubsequently, the detection results of the n detection frames are processed to obtain a first output frame F1And (5) corresponding detection results.
In this embodiment, the frame f is detected as the first frame f11With reference to the generation timing of the detection light pulse, and the subsequent detection frame f12～f 1nThe detected light pulse of (a) is delayed frame by frame to gradually delay the multiple reflection light and the portion of the one reflection light out of the reception time range of the shutter G3.
In a specific embodiment, the detection light pulses are delayed frame by frame at the same time interval t. Setting the delay time of a first detection light pulse of a first detection frame as 0, delaying a second detection light pulse of a second detection frame relative to the first detection light pulse by t, and setting the total delay time as t; the delay time of the third detection light pulse of the third detection frame with respect to the second detection light pulse is also t, the total delay time is 2t, and so on, the detection light pulse of the nth detection frame is delayed with respect to the detection light pulse of the (n-1) th detection frame by t, and the total delay time is (n-1) t.
In other embodiments, the delay time interval may be reduced frame by frame, and the delay time interval is larger between the first several detection frames to improve the efficiency, for example, the second detection pulse light is delayed by 3t with respect to the first detection pulse light, the third detection pulse light is delayed by 2t with respect to the second detection pulse light, and so on.
The frame-by-frame delay of the detection light pulse can be realized by controlling the light emitting time sequence of the light source module of the time-of-flight sensing system.
Step S102: and receiving reflected light of the detection light pulse after being reflected by the object to be detected, and acquiring a plurality of initial depth values respectively corresponding to each detection frame.
The depth value may be a distance, or may be another parameter corresponding to the distance. The depth value is subsequently described as being equivalent to the distance.
The initial depth values may be calculated according to equation (4), and in the case where reflected light, whether once reflected light or multiple reflected light, is received by the shutters G2 and G3, although the reflected light energy received by the shutter G3 gradually increases and the reflected light energy received by the shutter G2 gradually decreases as the detection pulse light moves backward, the calculated initial depth values are the same.
When the multiple reflection light delayed from the one reflection light starts to be gradually moved out of the reception time region of the shutter G3, the multiple reflection light energy received by the G3 is reduced, thereby causing the initial depth value calculated according to the formula (4) to be gradually reduced.
When the multiple reflected light delayed from the one reflected light is completely shifted out of the receiving time region of the shutter G3 (as reflected light LB12 in fig. 2 b), the shutter G2 will not be able to receive the reflected light energy, the distance coefficient is equal to 1, and the detection light pulse continues to be delayed, and the distance coefficient is still 1.
And in a plurality of detection frames corresponding to a single output frame, the maximum delay time of the detection light pulse is smaller than or equal to the pulse width T of the detection light pulse. When the delay time is longer than T, part of the primary reflected light will exceed the reception time of the shutter G3, and a valid initial depth value can no longer be obtained.
Step S103: according to the distance coefficient corresponding to the initial depth, one of the initial depth values is selected as an actually-measured depth value of the output frame corresponding to the plurality of detection frames, the actually-measured depth value is smaller than the initial depth value corresponding to the first detection frame, and the initial depth value is positively correlated with the distance coefficient.
Since, in the case where there is only one reflected light, the energy integrated by G3 decreases only when the detection light pulse is shifted backward to cause the reflected light pulse to be shifted out of the reception time of the shutter G3, the resulting initial depth value decreases.
Therefore, the influence of multiple reflected lights on the detection result can be reduced at least to a certain extent by comparing the initial depth values of the multiple detection frames and selecting the initial depth value smaller than the initial depth value corresponding to the first detection frame as the actually-measured depth value.
In order to make the measured depth value closer to the actual distance, in an embodiment of the present invention, a method for selecting one of the initial depth values as the measured depth value includes: and acquiring a distance coefficient positively correlated with the initial depth value, and taking the initial depth value corresponding to the distance coefficient closest to a preset threshold value as the actual measurement depth value.
In particular, the distance coefficient may be selected
Figure BDA0002149058880000091
Wherein, G2 'and G3' are divided into reflected light energy accumulated by two shutters in sequence, G1 is the energy of the received ambient light, and G2 and G3 are the total energy of the reflected light and the ambient light accumulated by the two shutters in sequence respectively.
In one embodiment, the predetermined threshold is less than or equal to 1, when the shutter G2 does not receive any reflected light energy due to the backward movement of the detection light pulse, and the delayed portion of the multiple reflected light is shifted out of the acceptance range of the shutter G3, thereby completely eliminating the effect of the multiple reflected light on the detection distance. And when the distance coefficient y is 1, the corresponding initial depth value is the actual distance. Therefore, the initial depth value with the distance coefficient closest to the preset threshold value and smaller than 1 in each detection frame is selected as the actually measured depth value, and the highest detection accuracy can be obtained.
In other embodiments, a threshold range may be set, and an initial depth value corresponding to any distance coefficient within the threshold range may be used as the measured depth value. The size of the set threshold range can be adjusted according to the detection precision requirement. In one embodiment, the set threshold is in a range of 0.8 to 1.
In the actual detection process, the delay times and the delay time of the detection pulse light of each detection frame are reasonably set according to the distance measurement efficiency, the power consumption of the sensing system, the computing capacity and the like. In case the number of detection frames is sufficient and the delay time is sufficiently long, the initial depth value of the detection frame having the distance coefficient closest to 1 but smaller than 1 may be selected as the measured depth value.
However, since there is a limit to the accuracy control of the number of delays and the delay time in consideration of the power consumption and detection efficiency of the system, the threshold value may be set to be less than 1 or the threshold value range may be appropriately enlarged to reduce the power consumption and increase the frame rate when the accuracy requirement is satisfied.
By shifting the detection light pulse backward so that the multiple reflected light exceeds the reception range of the reflected light, the accuracy of distance measurement can be improved.
The time-of-flight sensing system comprises a pixel array composed of a plurality of pixel units; the initial depth value and the distance coefficient of each detection frame are required to be acquired for each pixel unit, so as to correct the detection result obtained by each pixel unit.
Referring to FIG. 4, for the first output frame F1Correspondingly outputting the measured depth value D1The first output frame F1Corresponding to n detection frames, obtaining initial depth values d for the n detection frames1～d1nProcessing is performed to select one of the initial depth values as the first output frame F according to the distance coefficients of the n detection frames1Output measured depth value D1。
Referring to FIG. 5, for the second output frame F2Correspondingly outputting the measured depth value D2Said second output frame F2Corresponding to n detection frames, obtaining initial depth values d for the n detection frames1n～d2nProcessing to obtain the second output frame F2Output measured depth value D2(ii) a Analogize in turn, for the m-th output frame FmCorrespondingly outputting the measured depth value DmSaid m-th output frame FmCorresponding to n detection frames, obtaining initial depth values d for the n detection framesm1～dmnProcessing to obtain the m-th output frame FmOutput measured depth value Dm。
In the detection process, in some specific embodiments, the scene change is not large, and the initial depth values obtained from the multiple detection frames of the first output frame may be processed, and in the process of obtaining the actually measured depth value, the proper delay times, delay time, and the like are obtained as the subsequent detection parameters. In other specific embodiments, the delay time of the detection light pulse corresponding to the actually-measured depth value of the first output frame may also be acquired as the fixed delay time Ts ', and in the detection process of the subsequent frame, the detection pulse light pulse delay Ts' may be directly detected, and the detection result of a single detection frame may be used as the actually-measured depth value of the corresponding output frame, so that the detection efficiency may be improved, and the power consumption of the system may be reduced.
The invention further provides a flight time sensing system.
Fig. 6 is a schematic structural diagram of a time-of-flight sensing system according to an embodiment of the present invention.
The time-of-flight sensing system comprises: a light source module 701, a sensing module 702, a control module 703 and a processing module 704.
The light source module 701 is configured to emit detection light pulses, where the detection light is pulse detection light, and the light source module 701 is configured to sequentially emit the detection light pulses according to a set time sequence.
The sensing module 702 includes a sensing array formed by a plurality of pixel units, and is configured to receive reflected light of the detection light pulse after being reflected by the object to be measured, and obtain characteristics of the reflected light. Each pixel cell receives the reflected light and converts the light signal into an electrical signal. Each pixel unit is connected to an integration circuit, and obtains the charge amount corresponding to the flight time of light by integrating the electrical signal converted by the reflected light. The integrating circuit comprises three shutters G1-G3 which can be respectively realized through a capacitance structure, ambient light and reflected light are received by pixel units of the sensing array, optical signals are converted into electric signals, the electric signals are subjected to charge accumulation through the shutters G1, G2 and G3, and the charge amount is in direct proportion to light energy.
The control module 703 is connected to the light source module 701, and configured to control the light source module 701 to delay detection of light pulses frame by frame according to a detection frame sequence. In one embodiment, the light source module 701 may be controlled to delay the detection light pulse frame by frame at the same time interval. In other embodiments, the delay time interval may be reduced frame by frame, and the delay time interval is larger between the first several detection frames to improve efficiency. And in a plurality of detection frames corresponding to a single output frame, the maximum delay time of the detection light pulse is smaller than or equal to the pulse width of the detection light pulse.
The control module 703 is further connected to each pixel unit circuit of the sensing array 702, and is configured to control a receiving timing of the reflected light by each pixel unit.
The processing module 704 is connected to the sensing module 702, and is configured to perform the following processing: acquiring initial depth values of all detection frames according to the detection light and the reflected light; according to the distance coefficient corresponding to the initial depth value, selecting one of the initial depth values as an actually measured depth value of an output frame corresponding to the plurality of detection frames, wherein the actually measured depth value is smaller than the initial depth value corresponding to the first detection frame, and the initial depth value is positively correlated with the distance coefficient.
The time-of-flight sensing system comprises a pixel array composed of a plurality of pixel units; the processing module 704 is configured to obtain, for each pixel unit, an initial depth value of each detection frame, and obtain a measured depth value corresponding to each pixel unit.
In a specific embodiment, the processor is configured to obtain a distance coefficient corresponding to each initial depth value, and use an initial depth value corresponding to any distance coefficient within a set threshold range as the measured depth value.
In another specific embodiment, the processor is configured to obtain a distance coefficient corresponding to each initial depth value; and taking the initial depth value corresponding to the distance coefficient closest to the preset threshold value as the measured depth value.
In a specific embodiment, the control module 703 is configured to control two shutters to sequentially collect energy of reflected light, where the distance coefficient corresponding to the initial depth value is a ratio of reflected light energy collected by the second shutter to total reflected light energy collected by the two shutters.
In some embodiments, the processing module 704 may further obtain, as subsequent detection parameters, appropriate delay times, and the like in the process of obtaining actually measured depth values by processing the initial depth values obtained for the multiple detection frames of the first output frame; the delay time corresponding to the actually measured depth value of the first output frame may also be obtained as the fixed delay time Ts ', and in the detection process of the subsequent frame, the light source module 701 may be directly controlled to detect the pulse light pulse delay Ts', and the detection result of a single detection frame is used as the actually measured depth value of the corresponding output frame, so that the detection efficiency may be improved, and the power consumption of the system may be reduced.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (16)

1. A method of ranging a time-of-flight sensing system, comprising:
delaying the detection light pulse frame by frame in the order of the plurality of detection frames;
receiving reflected light of the detection light pulse after being reflected by the object to be detected, and acquiring a plurality of initial depth values respectively corresponding to each detection frame;
according to the distance coefficient corresponding to the initial depth value, selecting one of the initial depth values as an actually-measured depth value of the output frame corresponding to the plurality of detection frames, wherein the actually-measured depth value is smaller than the initial depth value corresponding to the first detection frame, and the initial depth value is positively correlated with the distance coefficient.
2. A method of ranging of a time-of-flight sensing system according to claim 1, wherein the detection light pulses are delayed frame by frame at the same time interval.
3. A method of ranging of a time-of-flight sensing system according to claim 1, wherein the time-of-flight sensing system comprises a pixel array constituted by a plurality of pixel units; respectively acquiring initial depth values of all detection frames aiming at all pixel units; and respectively acquiring the actually measured depth values corresponding to the pixel units.
4. The method of claim 1, wherein the initial depth value corresponding to the distance coefficient closest to the predetermined threshold is used as the measured depth value.
5. A method as claimed in claim 1, wherein the initial depth value corresponding to any distance coefficient within a predetermined threshold range is used as the measured depth value.
6. A method as claimed in claim 4 or 5, wherein the reflected light is collected sequentially by two shutters, and the distance coefficient corresponding to the initial depth value is the ratio of the reflected light energy collected by the second shutter to the total reflected light energy collected by the two shutters.
7. A method of ranging as claimed in claim 1 wherein the maximum delay time of the detection light pulse is less than or equal to the pulse width of the detection light pulse within a plurality of detection frames corresponding to a single output frame.
8. A method of ranging of a time-of-flight sensing system according to claim 1, further comprising: acquiring the delay time of the detection light pulse corresponding to the initial depth value as the actually measured depth value, and taking the delay time as the fixed delay time; and delaying the detection light pulse of each subsequent detection frame by a fixed delay time, and taking the initial depth value of each subsequent detection frame as the actually-measured depth value.
9. A time-of-flight sensing system, comprising:
the light source module is used for emitting detection light pulses;
the sensing module is used for receiving reflected light of the detection light pulse after being reflected by an object to be detected;
the control module is connected with the light source module and used for controlling the light source module to delay the detection light pulse frame by frame according to the sequence of a plurality of detection frames;
the processing module is connected with the sensing module and used for carrying out the following processing: acquiring a plurality of initial depth values respectively corresponding to each detection frame according to the detection light and the reflected light; according to the distance coefficient corresponding to the initial depth value, selecting one of the initial depth values as an actually measured depth value of the output frame corresponding to the plurality of detection frames, wherein the actually measured depth value is smaller than the initial depth value corresponding to the first detection frame, and the initial depth value is positively correlated with the distance coefficient.
10. The time-of-flight sensing system according to claim 9, wherein the control module is configured to control the light source module to delay the detection light pulse frame by frame at the same time interval.
11. The time-of-flight sensing system of claim 9, comprising a pixel array comprised of a plurality of pixel cells; the processing module is used for respectively obtaining the initial depth value of each detection frame aiming at each pixel unit and respectively obtaining the actual measurement depth value corresponding to each pixel unit.
12. The time-of-flight sensing system of claim 9, wherein the processing module is configured to obtain the distance coefficient, and use an initial depth value corresponding to the distance coefficient closest to a preset threshold as the measured depth value.
13. The time-of-flight sensing system of claim 9, wherein the processing module is configured to obtain the distance coefficients, and use an initial depth value corresponding to any distance coefficient within a set threshold range as the measured depth value.
14. A time-of-flight sensing system according to claim 12 or 13, wherein the control module is configured to control the two shutters to sequentially collect energy of the reflected light, and the distance coefficient corresponding to the initial depth value is a ratio of the energy of the reflected light collected by the second shutter to the total energy of the reflected light collected by the two shutters.
15. The time-of-flight sensing system of claim 9, wherein the maximum delay time of the detection light pulse is less than or equal to the pulse width of the detection light pulse within a plurality of detection frames corresponding to a single output frame.
16. The time-of-flight sensing system according to claim 9, wherein the processing module is further configured to obtain a delay time of the detected light pulse corresponding to the initial depth value as the measured depth value, and use the delay time as a fixed delay time; the control module is used for controlling the light source module to delay the detection light pulse of each subsequent detection frame by a fixed delay time; the processing module is used for taking the initial depth value of each subsequent detection frame as the measured depth value.
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