WO2022188885A1 - 飞行时间测量方法、装置及时间飞行深度相机 - Google Patents

飞行时间测量方法、装置及时间飞行深度相机 Download PDF

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WO2022188885A1
WO2022188885A1 PCT/CN2022/080530 CN2022080530W WO2022188885A1 WO 2022188885 A1 WO2022188885 A1 WO 2022188885A1 CN 2022080530 W CN2022080530 W CN 2022080530W WO 2022188885 A1 WO2022188885 A1 WO 2022188885A1
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time
signal acquisition
sampling
flight
grayscale information
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PCT/CN2022/080530
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English (en)
French (fr)
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马宣
王兆民
周兴
黄源浩
肖振中
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奥比中光科技集团股份有限公司
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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
    • 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
    • G01S17/46—Indirect determination of position data
    • G01S17/48—Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
    • 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
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • 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
    • 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
    • G01S7/4808—Evaluating distance, position or velocity data
    • 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

Definitions

  • the present application relates to the technical field of optical measurement, and in particular, to a time-of-flight measurement method and device, and a time-of-flight depth camera.
  • ToF Time-of-Flight, time-of-flight
  • ToF time-of-Flight
  • dToF direct-TOF
  • the transmitted optical signal is periodically modulated, and the phase delay of the reflected optical signal relative to the transmitted optical signal is measured.
  • the measurement technology in which the phase delay is calculated for the time of flight is called iToF (Indirect-TOF) technology.
  • CW Continuous Wave
  • PM Pulse Modulated
  • the measurement distance of the PM-iToF modulation technology measurement method is currently limited by the pulse width of the modulation and demodulation signal.
  • the pulse width of the modulation and demodulation signal needs to be extended. Extending will lead to an increase in power consumption and a decrease in measurement accuracy, which also fails to meet market demands.
  • CW-iToF technology is mainly used in measurement systems based on multi-tap sensors, and the core measurement algorithm is a modulation and demodulation method with different phases.
  • the demodulated energy integration devices share the same pixel (ie, photodiode or other photosensitive element) when performing photon integration.
  • pixel ie, photodiode or other photosensitive element
  • taps readout and charge accumulation devices
  • the embodiments of the present application provide a time-of-flight measurement method, device, and time-of-flight depth camera, so as to at least solve the problem that in the current CW-iToF technology, the demodulation time of multiple taps of the sensor of the flight measurement system is subject to equal sampling time length limit issue.
  • a first aspect of the embodiments of the present application provides a time-of-flight measurement method, including: for a test object irradiated by a modulated continuous carrier beam, controlling M signal acquisition components to sequentially start continuous sampling time within a customized detection sampling period interval, wherein the customized detection sampling period includes K original detection sampling periods T, M and K are both positive integers greater than 1, and the sampling time interval length of each of the signal acquisition components is (K/M)*T; Obtaining grayscale information sets corresponding to preset four-phase offsets for each of the signal acquisition components, wherein each grayscale information in the grayscale information set corresponds to different phase offsets; The grayscale information set of the signal acquisition component determines the flight time corresponding to the object to be measured.
  • a second aspect of the embodiments of the present application provides a time-of-flight measurement device, including: a signal acquisition component start-up unit, configured to control M signal acquisition components to perform custom detection for an object to be measured irradiated by a modulated continuous carrier beam
  • the continuous sampling time interval is sequentially started in the sampling period, wherein the customized detection sampling period includes K original detection sampling periods T, M and K are both positive integers greater than 1, and the length of the sampling time interval of each of the signal acquisition components is (K/M)*T;
  • an offset grayscale sampling unit configured to obtain grayscale information sets corresponding to preset four-phase offsets of each of the signal acquisition components, wherein each of the grayscale information sets The grayscale information corresponds to different phase offsets respectively;
  • the flight time determination unit is configured to determine the flight time corresponding to the object to be measured according to the grayscale information set of each of the signal acquisition components.
  • a third aspect of the embodiments of the present application provides a time-of-flight depth camera, including: a transmitting module, including a light source and a light modulator, the light modulator is configured to control the light source to emit a modulated continuous carrier beam toward the object to be measured; receiving The module includes an image sensor composed of at least one pixel, and each of the pixels includes a plurality of signal acquisition components for receiving the light signal reflected from the object to be measured; the control module is connected with the transmitting module and the receiving module, and is configured to: for the object to be tested irradiated by the modulated continuous carrier beam, control M signal acquisition components to sequentially start continuous sampling time intervals within a customized detection sampling period, wherein the customized detection sampling period includes K original detections
  • the sampling periods T, M and K are all positive integers greater than 1, and the length of the sampling time interval of each of the signal acquisition components is (K/M)*T; the four-phase preset corresponding to each of the signal acquisition components is obtained.
  • a grayscale information set of offsets wherein each grayscale information in the grayscale information set corresponds to different phase offsets respectively; according to the sampling time interval of each of the signal acquisition components and the corresponding grayscale information set , and determine the flight time corresponding to the object to be tested.
  • a fourth aspect of the embodiments of the present application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, when the processor executes the computer program Implement the steps of the method as described above.
  • a fifth aspect of the embodiments of the present application provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.
  • a sixth aspect of the embodiments of the present application provides a computer program product, which, when the computer program product runs on an electronic device, enables the electronic device to implement the steps of the above method.
  • setting a custom detection sampling period larger than the original detection sampling period for the measurement system can increase the sampling time length of each signal acquisition component, so that the crosstalk can be reduced without affecting the measurement function of the time-of-flight measurement sensor.
  • the photons are reduced relative to the signal photons, increasing the signal-to-noise ratio of the signal.
  • FIG. 1 shows a schematic structural principle diagram of an example of a depth camera according to an embodiment of the present application
  • Fig. 2 shows the tap sampling signal distribution diagram of an example when performing charge integration ranging according to multi-tap in the CW-iToF technology
  • FIG. 3 shows a flowchart of an example of a time-of-flight measurement method according to an embodiment of the present application
  • FIG. 4 shows a flowchart of an example of updating the sampling time interval of each signal acquisition component according to an embodiment of the present application
  • FIG. 5 shows a flowchart of an example of determining the flight time of the corresponding object to be tested according to an embodiment of the present application
  • FIG. 6 shows a structural block diagram of an example of a time-of-flight measurement device according to an embodiment of the present application
  • FIG. 7 shows a schematic diagram of the effect of an example in which time signal crosstalk and space signal crosstalk affect tap sampling results
  • FIG. 8 shows a flowchart of an example of a time-of-flight measurement method according to an embodiment of the present application
  • FIG. 9 shows a flowchart of an example of updating the K value corresponding to the sampling period of the custom probe according to an embodiment of the present application.
  • FIG. 10 shows a block diagram of the structure of an example of a time-of-flight measurement device according to an embodiment of the present application
  • FIG. 11 shows a flowchart of an example of a time-of-flight measurement method according to an embodiment of the present application
  • FIG. 12 shows a flowchart of an example of determining each sampling time interval in a probe sampling period according to an embodiment of the present application
  • FIG. 13 shows a flowchart of an example of determining the flight time of the corresponding object to be measured according to each grayscale information according to an embodiment of the present application
  • FIG. 14 shows a structural block diagram of an example of a time-of-flight measurement device according to an embodiment of the present application.
  • FIG. 15 is a schematic diagram of an example of an electronic device according to an embodiment of the present application.
  • the term “if” may be contextually interpreted as “when” or “once” or “in response to determining” or “in response to detecting” .
  • the phrases “if it is determined” or “if the [described condition or event] is detected” may be interpreted, depending on the context, to mean “once it is determined” or “in response to the determination” or “once the [described condition or event] is detected. ]” or “in response to detection of the [described condition or event]”.
  • the electronic devices described in the embodiments of the present application include, but are not limited to, other portable devices such as mobile phones, laptop computers, or tablet computers with touch-sensitive surfaces (eg, touch screen displays and/or touch pads).
  • other portable devices such as mobile phones, laptop computers, or tablet computers with touch-sensitive surfaces (eg, touch screen displays and/or touch pads).
  • touch-sensitive surfaces eg, touch screen displays and/or touch pads.
  • the above-described device is not a portable communication device, but a computer having a touch-sensitive surface (eg, a touch screen display).
  • electronic devices including displays and touch-sensitive surfaces are described. It should be understood, however, that the electronic device may include one or more other physical user interface devices such as a physical keyboard, mouse, and/or joystick.
  • Various applications that may be executed on an electronic device may use at least one common physical user interface device, such as a touch-sensitive surface.
  • a touch-sensitive surface One or more functions of the touch-sensitive surface and corresponding information displayed on the terminal may be adjusted and/or changed between applications and/or within respective applications.
  • the common physical architecture of the terminal eg, touch-sensitive surface
  • FIG. 1 shows a schematic structural principle diagram of an example of a time-of-flight depth camera according to an embodiment of the present application.
  • the time-of-flight depth camera 10 includes a transmitter module 11 , a receiver module 12 and a control module 13 , and the control module 13 is connected to the transmitter module 11 and the receiver module 12 .
  • the transmitting module 11 can transmit an optical signal (for example, a modulated continuous carrier beam) 102 to the object to be measured 20, and the receiving module 12 can receive the optical signal 103 reflected back from the object to be measured 20, and through the control module 13, The reflected light signal can be calculated to obtain the distance 104 from the object to be measured 20 .
  • the sampling operation of the receiving module 12 can also be regulated by the control module 13, for example, the sampling period or time can be regulated, so as to meet the requirements of different measurement scenarios.
  • time-of-flight depth camera 10 may also include a color camera, an infrared camera, an IMU and other devices, and the combination with these devices can realize more abundant functions, such as 3D texture modeling, infrared face recognition, SLAM and other functions.
  • the transmitting module 11 may include a light source (not shown) and a light modulator (not shown), and the light source may be controlled to emit a modulated continuous carrier beam toward the object to be measured 20 through the light modulator.
  • the receiving module 12 may include an image sensor composed of at least one pixel, and each pixel includes a plurality of signal acquisition components.
  • the signal collection component may refer to a component that collects optical signals, which may be a device for reading out and accumulating charges, for example, the signal collection component may use a tap.
  • the time-of-flight camera 10 can adopt the indirect time-of-flight measurement method, and can modulate the power waveform of the emitted light to be close to a sine wave (or other waveform, such as a square wave), demodulate a device (such as a sensor, i-TOF Sensor) ) energy-integrates the power of the received light over different time periods.
  • a device such as a sensor, i-TOF Sensor
  • the demodulation device will have several different acquisition time periods. This time-segment acquisition of the sinusoidal signal of the echo is equivalent to multi-point sampling of the sinusoidal signal.
  • the demodulation device outputs a plurality of sampling values of the echo sinusoidal signal, so that the control module 13 calculates the phase delay of the echo sinusoidal signal, and calculates the flight time of the optical signal between the time-of-flight depth camera 10 and the measured object 20 distance.
  • the demodulated energy integration devices all share the same pixel (ie photodiode or other photosensitive elements) when performing photon integration.
  • pixel ie photodiode or other photosensitive elements
  • taps several different readout and charge accumulation devices
  • the signal gain and dark current between different taps are inconsistent.
  • it is necessary to sample the sine wave signal corresponding to different time periods including sub-period sampling (that is, sampling by multiple taps in one cycle) and sub-exposure sampling (that is, in different exposure times, respectively
  • the sampling time of the tap is phase-delayed).
  • the cycle-by-cycle sampling method in which multiple taps are time-divided in one cycle is often not accurate due to the inconsistency of sampling interference factors (for example, gain and dark current) of different taps. Calculates the value of the distance the light flies. At this time, through the sampling method of sub-exposure, the same tap is collected multiple times, and the data collected multiple times are used for addition, subtraction, multiplication and division operations, so as to eliminate the influence of the sampling interference factor item, and finally achieve the purpose of improving the accuracy of distance measurement.
  • sampling interference factors for example, gain and dark current
  • the demodulation time configuration of multiple taps can only select multiple taps with the same energy integration time due to the limitation of the algorithm (that is, with equal energy integration time in the detection period sampling time).
  • FIG. 2 shows an example of a tap sampled signal distribution diagram when charge integration ranging is performed according to multiple taps in the CW-iToF technology.
  • FIG. 3 shows a flowchart of an example of a time-of-flight measurement method according to an embodiment of the present application.
  • the execution subject of the embodiment of the present application it may be various measurement systems or processors with computing or processing functions, for example, it may be the control module 13 in the time-of-flight depth camera 10 .
  • a plurality of signal acquisition components are controlled to sequentially start continuous sampling time intervals within one detection sampling period.
  • the durations corresponding to the sampling time intervals of each signal acquisition component are different from each other, that is, the start time points of the sampling operations corresponding to different signal acquisition components are different, and the sampling time lengths corresponding to different signal acquisition components are different. There are also differences between.
  • each signal acquisition component (also referred to as a tap) in a pixel may be sequentially turned on at different time points in the detection sampling period, and each signal acquisition component may have different sampling time lengths.
  • there are four taps in one pixel and multiple taps can be controlled to be continuously turned on in one detection period during one exposure time and the integration sampling time is different.
  • the detection sampling period is T
  • tap A can be the first one. is turned on and the sample time length can be T/8
  • tap B can be turned on later and the sample time length can be T/4 or other values.
  • each signal acquisition component may be non-fixed, for example, it may be adjusted according to different business scenarios or requirements.
  • the above-mentioned “multiple signal acquisition components” can be used to represent at least two signal acquisition components, and generally three or more than four.
  • step 320 for each signal acquisition component, a corresponding preset four-phase offset is applied to the signal acquisition component to obtain a corresponding grayscale information set.
  • each grayscale information in the grayscale information set corresponds to a different phase shift amount, respectively.
  • phase delay amounts may be applied to the emitted light signals, respectively, and the signal acquisition components may be invoked to acquire corresponding grayscale information.
  • each tap can collect signals separately to complete a frame of measurement when no phase delay is applied; then, after applying phase delays of 90 degrees, 180 degrees and 270 degrees to the transmitted signal, the corresponding measurement frames are repeatedly collected respectively, A total of 4 frames of sampled signals can be obtained.
  • the flight time corresponding to the object to be measured is determined according to the grayscale information set of each signal acquisition component. For example, the calculation can be performed based on a preset relational expression between the grayscale sampling signal and the flight time, so as to obtain the flight time corresponding to the object to be measured, and more details will be described below.
  • a new time-of-flight calculation method in which the integral calculation process of CW-iToF in one detection sampling period is simulated as the process of the cumulative amount of pulse modulation, so that the demodulation time of multiple taps is not affected by the
  • the same integral sampling time limit extends the applicable range of the sensor.
  • it needs to be measured separately by different signal acquisition components, which is equivalent to averaging multiple measurements, and also improves the accuracy of the determined flight time.
  • the measurement system may further determine the distance to the object to be measured according to the flight time for the object to be measured.
  • the distance between the measurement system and the object to be measured can be determined by the following formula:
  • d is the distance from the object to be measured
  • C is the speed of light
  • t is the flight time
  • FIG. 4 shows a flowchart of an example of updating the sampling time interval of each signal acquisition component according to an embodiment of the present application.
  • a sampling interval setting instruction is obtained.
  • the measurement system may receive a sampling duration setting instruction from the user terminal.
  • step 420 based on the sampling interval setting instruction, update the sampling time interval corresponding to each signal acquisition component respectively. Therefore, different sampling time intervals can be set for each signal acquisition component, and can be adjusted by means of command interaction, which meets the needs of different users or business scenarios.
  • FIG. 5 shows a flowchart of an example of determining the flight time of the corresponding object to be tested according to an embodiment of the present application.
  • step 510 for each signal acquisition component, a corresponding initial flight time is determined based on the sampling time interval of the signal acquisition component and the collected grayscale information set.
  • step 520 the flight time corresponding to the object to be measured is determined based on the initial flight time determined by each signal acquisition component.
  • the initial flight times of different signal acquisition components can be integrated through various statistical methods, so as to obtain the final flight time corresponding to the object to be measured.
  • a corresponding average value may be calculated from the initial flight times of multiple signal acquisition components to determine the flight time of the corresponding object to be measured.
  • the phase time delay can be directly used as the flight time corresponding to the object to be tested, or the corresponding flight time can be obtained by calibrating the average value corresponding to each initial flight time to eliminate some other unspecified factors. the resulting delay.
  • the sampling results of multiple taps are comprehensively considered, and the sampling time lengths of each tap are inconsistent.
  • the design requirements for the sampling time length of the taps can be reduced in design. , and can improve the measurement accuracy.
  • the initial flight time may be determined according to each grayscale information and a preset initial flight time relationship.
  • the initial flight time relational expression may be an association relationship between the grayscale information and the initial flight time.
  • the initial flight time relational expression can adopt the example in the following formula (2):
  • t' A represents the initial flight time corresponding to the signal acquisition component A
  • T represents the detection sampling period
  • the sampling time interval of the signal acquisition component A is [0,3/4T]
  • I A,0 Indicates the grayscale information corresponding to the signal acquisition component A when the phase offsets are 0, 1/4T, 2/4T and 3/4T respectively.
  • the time-of-flight measurement system is an imaging device based on a photoelectric conversion device, which is essentially a photon energy integration device, and the tap is used as a readout and storage element, and there are amplifying circuits and dark current noise inside.
  • the light energy collected by the tap is the accumulated photocharge and not quantified.
  • the number of incident photons can be used to characterize the light energy collected by the tap.
  • the relationship between the imaged gray value I (which can also be written as the light energy collected by the tap) and the number of incident photons C Signal,Photon , the tap gain G, and the dark current C Dark,Electron is:
  • the gray value I output by the tap represents the amount of charge collected by the pixel, which is the charge generated by the photoelectric effect emitted by light incident on the pixel, and can also be defined as the number of collected photons.
  • the grayscale values sampled by the two taps A and B are:
  • the grayscale values collected by the two taps form a two-point sampling of the sinusoid.
  • the number of signal photons received by the tap is the integral of the time distribution of the number of incident photons:
  • T can represent the modulation period (ie, the detection sampling period)
  • a represents the time-varying amplitude of the number of received photons
  • t 0 is the time when the tap starts to integrate in a single cycle
  • ⁇ t is the integration time of the tap in a single cycle (ie , sampling time length)
  • t' is the fixed phase delay caused by the time-of-flight of the waveform light
  • ⁇ (Ambient, Photon) is the ambient photon time density, and is a constant related to t 0 , ⁇ t and T, which is a characteristic quantity obtained by the intermediate process of photon number integration.
  • One exposure can be completed by repeating the accumulation of N detection cycles, and one subframe can be collected.
  • the modulated continuous carrier beam is a sine wave, of course, it can also be replaced with other waveforms such as a square wave.
  • a two-tap sensor is taken as an example for description, and it can also be a 3-tap sensor, a 4-tap sensor, or the like.
  • the two taps are continuously turned on and the integration sampling time is different from each other.
  • the integration time of the two taps can be set arbitrarily.
  • the taps A and B are set to 3T/4 and T/4 respectively; that is, in a detection period,
  • the integral sampling time of tap A ie, the sampling time interval
  • t A and t B are the time when the two taps start to collect, which are 0 and 3T/4 respectively. and then have
  • the errors caused by the gain and dark current of different taps need to be calculated. can be eliminated and can be sampled at the same tap by collecting multiple phase delays.
  • phase delay exposure acquisition operations may be performed on each tap respectively, that is, four exposures are performed when t A is 0, T/4, 2T/4 and 3T/4 respectively. It should be noted that, in the sub-exposure sampling process of the embodiment of the present application, four exposures are used, and the exposure phase delay is fixed, which is completely different from the traditional four-phase sampling method.
  • the gray value output of each tap per frame can be obtained, and then combining the four exposures to obtain the gray value I collected under the four-phase delay exposure, we can obtain The relationship between phase delay and time delay, and because of the relationship between phase delay and four-phase gray value The time delay for each tap can be calculated.
  • phase delay exposure acquisition operations are performed on each tap respectively, and the respective time delays are calculated by using the grayscale acquisition results of different phases and the corresponding sampling time intervals, and each time delay is calculated. Averaging is performed to finally obtain a phase delay with higher accuracy.
  • the initial flight time may also be calculated in other ways.
  • a phase offset information relational expression corresponding to the grayscale information may be determined.
  • the phase offset information relational expression may be a relational expression that includes an initial time-of-flight variable and is used to express the phase offset information.
  • phase delay generated by the signal acquisition component A after delayed exposure can be expressed by the following phase offset information relationship:
  • ⁇ A may represent the phase offset information corresponding to the signal acquisition component A.
  • phase offset information can be determined according to each grayscale information. It should be understood that there is an inherent relationship between the phase offset information and the grayscale information of different offsets, which can be expressed as:
  • the integration time of the taps is not limited, and the time-of-flight of light can also be calculated, so that the demodulation time of multiple taps is not limited by the same integration time, which expands the time-of-flight measurement system sensor. Scope of application.
  • FIG. 6 shows a structural block diagram of an example of a time-of-flight measurement device according to an embodiment of the present application.
  • the time-of-flight measurement device 600 includes a signal acquisition component start-up unit 610 , an offset grayscale sampling unit 620 and a time-of-flight determination unit 630 .
  • the signal acquisition component start-up unit 610 is configured to control a plurality of signal acquisition components to be sequentially turned on in one detection sampling period for the object under test irradiated by the modulated continuous carrier beam, and each has a sampling time interval with different lengths.
  • the offset grayscale sampling unit 620 is configured to obtain, for each of the signal acquisition components, a grayscale information set corresponding to a preset four-phase offset of the signal acquisition component, wherein each grayscale in the grayscale information set The information corresponds to different phase offsets among the four phase offsets, respectively.
  • the flight time determining unit 630 is configured to determine the flight time corresponding to the object to be measured according to the grayscale information set of each of the signal acquisition components.
  • the demodulated energy integration devices share the same pixel (ie, photodiode or other photosensitive element) when performing photon integration, and different readout and charge accumulation devices (called taps) are connected to the same pixel.
  • taps different readout and charge accumulation devices
  • FIG. 7 is a schematic diagram illustrating the effect of an example in which the time signal crosstalk and the space signal crosstalk affect the tap sampling result.
  • temporal signal crosstalk means that, due to the spatial area of pixels and the discrete spatial distribution of taps, as shown in Figure 7, some of the charge signals generated when the first tap is turned on for acquisition do not enter the tap due to the spatial distance; And when the next tap starts acquisition, it goes to the next tap to generate a signal.
  • the spatial crosstalk means that when a certain tap turns on charge collection, the gradient of the potential field of the tap pointing to the turn-on charge collection increases, and the gradient of the potential field of the tap that does not turn on the charge collection decreases; however, even if the charge collection is not turned on
  • the tap potential field gradient is low, however, as shown in Figure 7, due to the Brownian motion of charges, there will still be signal charges in the pixel close to the unopened tap position into the unopened tap, resulting in spatial signal crosstalk. Therefore, both temporal crosstalk and spatial crosstalk are a kind of noise in the measurement, which will affect the measurement accuracy.
  • FIG. 8 shows a flowchart of an example of a time-of-flight measurement method according to an embodiment of the present application.
  • the execution subject of the embodiment of the present application it may be various measurement systems or processors with computing or processing functions, for example, it may be the control module 13 in the time-of-flight depth camera 10 .
  • the M signal acquisition components are controlled to sequentially start continuous sampling time intervals within the customized detection sampling period.
  • the customized detection sampling period includes K original detection sampling periods T, M and K are both positive integers greater than 1, and the sampling time interval length of each signal acquisition component is (K/M)*T. Therefore, the sampling time interval of the signal acquisition component is extended by K times.
  • the customized detection sampling period includes multiple original detection sampling periods (eg, sine wave periods), which expands the detection period and lays a foundation for expanding the sampling time length of each signal acquisition component.
  • original detection sampling periods eg, sine wave periods
  • step 820 a grayscale information set corresponding to preset four-phase offsets of each signal acquisition component is acquired.
  • each grayscale information in the grayscale information set corresponds to different phase shift amounts among the four phase shift amounts, respectively.
  • step 830 the time-of-flight corresponding to the object to be measured is determined according to the grayscale information set of each signal acquisition component.
  • a new tap demodulation method is proposed. Under the condition that the number of crosstalk photons cannot be changed, the energy integration time of each tap is increased, so that the crosstalk photon Compared with the reduction of signal photons, the signal-to-noise ratio of the signal is improved.
  • the method further includes: determining the distance to the object to be measured according to the time of flight corresponding to the object to be measured, for example, substituting the time of flight into the above formula (1) to obtain the relative distance from the object to be measured.
  • the measurement system may determine the corresponding initial flight time for each signal acquisition component based on the sampling time interval of the signal acquisition component and the collected grayscale information set. Further, based on the initial flight time determined by each signal acquisition component, the flight time corresponding to the object to be measured is determined. Exemplarily, an average value corresponding to the initial flight times of the plurality of signal acquisition components may be calculated to determine the flight time of the corresponding object to be measured.
  • FIG. 9 shows a flowchart of an example of updating the K value corresponding to the custom probe sampling period according to an embodiment of the present application.
  • a custom probe sampling period setting instruction is obtained.
  • the measurement system may receive a custom probe sampling period setting instruction from the user terminal.
  • step 920 the K value of the custom probe sampling period is updated based on the custom probe sampling period setting instruction. Therefore, a detection sampling period with an extended time length can be customized for the signal acquisition component, and can be adjusted by means of command interaction, which meets the needs of different users or business scenarios.
  • the corresponding initial flight time can be determined in the following ways:
  • t' A represents the initial flight time corresponding to the signal acquisition component A
  • the custom detection sampling period is 3T
  • the sampling interval time of the signal acquisition component A in the four-tap sensor is [0,3/4T]
  • I A,0 Indicates the grayscale information corresponding to the signal acquisition component A when the phase offsets are 0, 1/4T, 2/4T and 3/4T respectively.
  • equation (11) The derivation details for equation (11) will be described in detail below by taking a four-tap sensor as an example. It should be understood that, in this embodiment of the present application, a two-tap sensor may also be used, that is, the two taps have equal sampling time lengths in one custom detection period.
  • the integration time of each tap A, B, C, and D in the four-tap sensor is T/4, and the corresponding time delays are:
  • the integration time collected by the four taps in the four-tap sensor can be increased under the condition that the total number of detection cycles remains unchanged, that is, four
  • the sum of the integration time of the taps corresponds to multiple detection periods, which greatly increases the number of signal photons, while the number of crosstalk photons remains unchanged, which can greatly improve the signal-to-noise ratio.
  • K original detection sampling periods T may be combined into a customized detection sampling period, and for each tap, the original sampling time length is T/4, and after the extended period The sampling time length becomes KT/4.
  • the number K of the original sampling periods in the custom probing sampling period can be set to 3, and the time t A , t B , t C , and t D at which the four taps start to collect are 0, t B , t C , and t D respectively.
  • the cycle-by-cycle sampling operation is completed. Furthermore, four phase delay exposure acquisitions are performed for each tap respectively, and t A is taken as 0, Take four exposures.
  • the time-of-flight calculation operation can be completed by the above-mentioned relational expressions.
  • the signal photons integrated by a single tap increase, but the total number of crosstalk photons remains unchanged, the signal-to-noise ratio of the signal is relatively increased, and the measurement accuracy is improved.
  • FIG. 10 shows a structural block diagram of an example of a time-of-flight measurement apparatus according to an embodiment of the present application.
  • the time-of-flight measurement device 1000 includes a signal acquisition component start-up unit 1010 , an offset grayscale sampling unit 1020 and a time-of-flight determination unit 1030 .
  • the signal acquisition component starting unit 1010 is configured to control the M signal acquisition components to sequentially start continuous sampling time intervals within a custom detection sampling period for the object to be tested irradiated by the modulated continuous carrier beam, wherein the custom detection sampling period includes
  • the K original detection sampling periods T, M and K are all positive integers greater than 1, and the sampling time interval length of each of the signal acquisition components is (K/M)*T.
  • the offset grayscale sampling unit 1020 is configured to obtain grayscale information sets corresponding to preset four-phase offsets for each of the signal acquisition components, wherein each grayscale information in the grayscale information set is associated with different phases.
  • the offset corresponds to;
  • the flight time determining unit 1030 is configured to determine the flight time corresponding to the object to be measured according to the grayscale information set of each of the signal acquisition components.
  • FIG. 11 shows a flowchart of an example of a time-of-flight measurement method according to an embodiment of the present application.
  • the execution subject of the embodiment of the present application it may be various measurement systems or processors with computing or processing functions, for example, it may be the control module 13 in the time-of-flight depth camera 10 .
  • a single signal acquisition component is controlled to start a sampling time interval within the detection sampling period.
  • sampling time length of the tap can be set arbitrarily or as required. For example, when it is set to 3T/4, the tap can no longer collect the input energy corresponding to the remaining T/4, and can use this part. The energy is directly drawn and ignored.
  • step 1120 each grayscale information corresponding to the preset four-phase offset of the signal acquisition component is acquired.
  • a plurality of phase offsets may be applied to a single tap in a pixel respectively, and multiple exposures may be performed respectively so that the taps record a plurality of corresponding sampling values, so as to complete the sub-exposure sampling operation.
  • step 1130 the flight time corresponding to the object to be measured is determined according to each grayscale information.
  • the difficulty of chip design and processing can be reduced, the area of a single pixel can be reduced, and the resolution of the sensor can be improved.
  • the method further includes: determining the distance to the object to be measured according to the time of flight corresponding to the object to be measured, for example, substituting the time of flight into the above formula (1) to obtain the relative distance from the object to be measured.
  • FIG. 12 shows a flowchart of an example of determining each sampling time interval in a probe sampling period according to an embodiment of the present application.
  • a sampling time interval setting instruction is obtained.
  • the measurement system may receive the sampling time interval setting instruction from the user terminal.
  • each sampling time interval in the detection sampling period is determined according to the sampling time interval setting instruction.
  • different sampling time intervals can be set in the signal acquisition component, including the start time of each sampling stage and the corresponding sampling time length, which can be adjusted through command interaction to meet the needs of different users or business scenarios.
  • the flight time corresponding to the object to be measured may be determined according to each grayscale information and a preset flight time relationship.
  • the time-of-flight relational expression is an association relationship between grayscale information and time-of-flight. Therefore, the measurement system can directly substitute the grayscale information under different offsets into the relational expression for calculation, and quickly obtain the corresponding flight time.
  • the corresponding flight time can be determined by:
  • t' represents the flight time corresponding to the object to be measured
  • the time length of a single sampling interval of the signal acquisition component is 1/4T
  • I A,0 Indicates the grayscale information corresponding to the signal acquisition component A when the phase offsets are 0, 1/4T, 2/4T and 3/4T respectively.
  • FIG. 13 shows a flowchart of an example of determining the flight time of the corresponding object to be measured according to each grayscale information according to an embodiment of the present application.
  • phase offset information is expressed as a relational expression including time-of-flight variables.
  • step 1320 corresponding phase offset information is determined according to each grayscale information.
  • step 1330 according to the relationship between the phase offset information and the phase offset information, the time-of-flight variable is solved to obtain the time-of-flight corresponding to the object to be measured.
  • phase delay generated by a single tap after delayed exposure can be represented by the following phase offset information relationship:
  • phase offset information can be calculated as:
  • the calculation expression of the number of photons outputting the gray value of the tap is first defined, and the gray value output by the tap per frame can be calculated, and then combined with multiple exposures to obtain the four-phase delay (for example, the phase delay is 0, T/ 4, 2T/4 and 3T/4) respectively collected grayscale values under exposure, obtain the relationship between phase delay and time delay, and comprehensively consider the inherent relationship between phase delay and four-phase grayscale value, the time delay of taps can be calculated .
  • only one readout circuit can be implemented in one pixel (that is, the pixel has only one tap), and the sampling solution of the multi-tap sensor can be simulated by adjusting the start readout time and end readout time of the tap.
  • the adjustment process can still get more accurate measurement results. Since only one tap is used for a single pixel, the difficulty of circuit design is greatly reduced; at the same time, the area of a single pixel is reduced, so that the pixel can be made very small, thereby improving the resolution of the time-of-flight measurement chip.
  • FIG. 14 shows a structural block diagram of an example of a time-of-flight measurement apparatus according to an embodiment of the present application.
  • the time-of-flight measurement device 1400 includes a signal acquisition component start-up unit 1410 , an offset sampling unit 1420 and a time-of-flight determination unit 1430 .
  • the signal acquisition component starting unit 1410 is configured to control a single signal acquisition component to continuously start a plurality of sampling time intervals within the detection sampling period for the object under test irradiated by the modulated continuous carrier beam, wherein each of the sampling time intervals has equal The length of the sampling time interval.
  • the offset sampling unit 1420 is configured to acquire each grayscale information of the signal acquisition component corresponding to a preset four-phase offset.
  • the flight time determining unit 1430 is configured to determine the flight time corresponding to the object to be measured according to each of the grayscale information and the length of the sampling time interval.
  • FIG. 15 is a schematic diagram of an example of an electronic device according to an embodiment of the present application.
  • the electronic device 1500 of this embodiment includes: a processor 1510 , a memory 1520 , and a computer program 1530 stored in the memory 1520 and executable on the processor 1510 .
  • the processor 1510 executes the computer program 1530
  • the steps in the above embodiments of the flight time measurement method are implemented, for example, steps 310 to 330 shown in FIG. 3, or steps 810 to 830, or steps 1110 to 1130.
  • the processor 1510 executes the computer program 1530
  • the functions of the modules/units in the foregoing device embodiments are implemented, for example, the functions of the units 610 to 630 shown in FIG. 6 , or the functions of the units 1010 to 630 shown in FIG. 10 . 1030, or units 1410 to 1430 as shown in FIG. 14 .
  • the computer program 1530 may be divided into one or more modules/units, and the one or more modules/units are stored in the memory 1520 and executed by the processor 1510 to complete the this application.
  • the one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program 1530 in the electronic device 1500 .
  • the computer program 1530 may be divided into a signal acquisition component startup program module, an offset grayscale sampling program module, and a flight time determination program module.
  • the specific functions of each program module are as follows:
  • the signal acquisition component startup program module is configured to control a plurality of signal acquisition components to be turned on sequentially within a detection sampling period for the object to be tested irradiated by the modulated continuous carrier beam, and each has a sampling time interval with different lengths;
  • the offset grayscale sampling program module is configured to obtain, for each of the signal acquisition components, a grayscale information set corresponding to a preset four-phase offset of the signal acquisition component, wherein each grayscale information set in the grayscale information set is The degree information corresponds to different phase offsets in the four phase offsets respectively;
  • the flight time determination program module is configured to determine the flight time corresponding to the object to be measured according to the grayscale information set of each of the signal acquisition components.
  • the computer program 1530 may be divided into a signal acquisition component startup program module, an offset grayscale sampling program module, and a flight time determination program module.
  • the specific functions of each program module are as follows:
  • the signal acquisition component startup program module is configured to control the M signal acquisition components to sequentially start continuous sampling time intervals within a customized detection sampling period for the object to be tested irradiated by the modulated continuous carrier beam, wherein the customized detection sampling period Including K original detection sampling periods T, M and K are both positive integers greater than 1, and the sampling time interval length of each of the signal acquisition components is (K/M)*T;
  • the offset grayscale sampling program module is configured to obtain grayscale information sets corresponding to preset four-phase offsets of each of the signal acquisition components, wherein each grayscale information in the grayscale information set is respectively different from a different grayscale information set.
  • the phase offset corresponds to;
  • the flight time determination program module is configured to determine the flight time corresponding to the object to be measured according to the grayscale information set of each of the signal acquisition components.
  • the computer program 1530 may be divided into a signal acquisition component startup program module, an offset sampling program module, and a flight time determination program module.
  • the specific functions of each program module are as follows:
  • the signal acquisition component startup program module is configured to control a single signal acquisition component to start the sampling time interval within the detection sampling period for the object to be tested irradiated by the modulated continuous carrier beam;
  • an offset sampling program module configured to obtain each grayscale information of the signal acquisition component corresponding to a preset four-phase offset
  • the flight time determination program module is configured to determine the flight time corresponding to the object to be measured according to the respective grayscale information.
  • the electronic device 1500 may be a computing device such as a desktop computer, a notebook, a palmtop computer, and a cloud server.
  • the electronic device may include, but is not limited to, the processor 1510 and the memory 1520 .
  • FIG. 15 is only an example of the electronic device 1500, and does not constitute a limitation to the electronic device 1500.
  • the electronic device may further include an input/output device, a network access device, a bus, and the like.
  • the so-called processor 1510 may be a central processing unit (Central Processing Unit, CPU), or other general-purpose processors, digital signal processors (Digital Signal Processors, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), Field-Programmable Gate Array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
  • a general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
  • the memory 1520 may be an internal storage unit of the electronic device 1500 , such as a hard disk or a memory of the electronic device 1500 .
  • the memory 1520 may also be an external storage device of the electronic device 1500, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) equipped on the electronic device 1500 card, Flash Card, etc.
  • the memory 1520 may also include both an internal storage unit of the electronic device 1500 and an external storage device.
  • the memory 1520 is used to store the computer program and other programs and data required by the electronic device.
  • the memory 1520 may also be used to temporarily store data that has been output or will be output.
  • the disclosed apparatus/electronic device and method may be implemented in other manners.
  • the above-described embodiments of the apparatus/electronic device are only illustrative.
  • the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units. Or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented.
  • the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.
  • the above-mentioned units can be implemented in the form of hardware, or can be implemented in the form of software.
  • the integrated modules/units if implemented in the form of software functional units and sold or used as independent products, may be stored in a computer-readable storage medium.
  • the present application can implement all or part of the processes in the methods of the above embodiments, and can also be completed by instructing the relevant hardware through a computer program.
  • the computer program can be stored in a computer-readable storage medium, and the computer When the program is executed by the processor, the steps of the foregoing method embodiments can be implemented.
  • the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate form, and the like.
  • the computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, removable hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory) , Random Access Memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable media may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer-readable media Electric carrier signals and telecommunication signals are not included.

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Abstract

一种飞行时间测量方法、装置及时间飞行深度相机，该方法包括：针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间（810），定制探测采样周期包括K个原始探测采样周期T，M、K为大于1正整数，各个信号采集组件的采样时间区间长度为(K/M)*T；获取各个信号采集组件分别对应预设的四相位偏移量的灰度信息集（820），其中的各个灰度信息分别与不同的相位偏移量相对应；根据各个信号采集组件的灰度信息集，确定对应待测体的飞行时间（830）。增加单个抽头的积分时间，可提高信噪比。

Description

飞行时间测量方法、装置及时间飞行深度相机
本申请要求于2021年3月10日提交中国专利局，申请号为202110260194.9，发明名称为“飞行时间测量方法、装置及时间飞行深度相机”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光学测量技术领域，尤其涉及一种飞行时间测量方法、装置及时间飞行深度相机。
背景技术
ToF(Time-of-Flight，飞行时间)测距法是一种通过测量光脉冲在发射/接收装置和目标物体间的往返飞行时间来实现精确测距的技术。在ToF技术中直接对光飞行时间进行测量的技术被称为dToF(direct-TOF)；对发射光信号进行周期性调制，通过对反射光信号相对于发射光信号的相位延迟进行测量，再由相位延迟对飞行时间进行计算的测量技术被成为iToF(Indirect-TOF)技术。按照调制解调类型方式的不同可以分为连续波(Continuous Wave，CW)调制解调方式和脉冲调制(Pulse Modulated，PM)调制解调方式。
目前，PM-iToF调制技术测量手段的测量距离目前受限于调制解调信号的脉宽，当需要进行远距测量时，需要延长调制解调信号的脉宽，而调制解调信号脉宽的延长会导致功耗的增加和测量精度的下降，因而也无法满足市场需求。
此外，CW-iToF技术主要应用于基于多抽头传感器构建的测量系统，核心测量算法是一种不同相位的调制解调方式。然而，一般来说，解调的能量积分器件在进行光子积分时，都是共用同一个像素(即光电二极管或其它感光元件)。几个不同的读出和电荷累计器件(称为抽头)共同连接至同一个像素，在进行分时采集信号的过程中，难免出现不同抽头之间出现接收电荷信号的时间上的串扰和空间上的串扰，会影响到测量精度。
针对上述问题，目前业界暂无较佳的解决方案。
发明内容
鉴于此，本申请实施例提供了一种飞行时间测量方法、装置及时间飞行深度相机，以至少解决目前CW-iToF技术中，飞行测量系统传感器的多个抽头的解调时间受相等的采样 时间长度限制的问题。
本申请实施例的第一方面提供了一种飞行时间测量方法，包括：针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间，其中所述定制探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个所述信号采集组件的采样时间区间长度为(K/M)*T；获取各个所述信号采集组件分别对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应；根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间。
本申请实施例第二方面提供了一种飞行时间测量装置，包括：信号采集组件启动单元，被配置为针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间，其中所述定制探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个所述信号采集组件的采样时间区间长度为(K/M)*T；偏移灰度采样单元，被配置为获取各个所述信号采集组件分别对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应；飞行时间确定单元，被配置为根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间。
本申请实施例第三方面提供了一种时间飞行深度相机，包括：发射模块，包括光源和光调制器，所述光调制器用于控制所述光源朝向待测体发射经调制的连续载波光束；接收模块，包括由至少一个像素组成的图像传感器，每个所述像素包括多个信号采集组件，用于接收从所述待测体反射回的光信号；控制模块，与发射模块和接收模块连接，并被配置为：针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间，其中所述定制探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个所述信号采集组件的采样时间区间长度为(K/M)*T；获取各个所述信号采集组件分别对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应；根据各个所述信号采集组件的采样时间区间和相应的灰度信息集，确定对应所述待测体的飞行时间。
本申请实施例的第四方面提供了一种电子设备，包括存储器、处理器以及存储在所述存储器中并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现如上述方法的步骤。
本申请实施例的第五方面提供了一种计算机可读存储介质，所述计算机可读存储介质存储有计算机程序，所述计算机程序被处理器执行时实现如上述方法的步骤。
本申请实施例的第六方面提供了一种计算机程序产品，当计算机程序产品在电子设备上运行时，使得电子设备实现如上述方法的步骤。
本申请实施例与现有技术相比存在的有益效果是：
通过本申请实施例，为测量系统设置大于原始探测采样周期的定制探测采样周期，可以增大每个信号采集组件的采样时间长度，使得在不影响时间飞行测量传感器的测量功能前提下，降低串扰光子相对于信号光子降低，增加信号的信噪比。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1示出了根据本申请实施例的深度相机的一示例的结构原理示意图；
图2示出了根据CW-iToF技术中多抽头进行电荷积分测距时的一示例的抽头采样信号分布图；
图3示出了根据本申请实施例的飞行时间测量方法的一示例的流程图；
图4示出了根据本申请实施例的更新各个信号采集组件的采样时间区间的一示例的流程图；
图5示出了根据本申请实施例的确定对应待测体的飞行时间的一示例的流程图；
图6示出了根据本申请实施例的飞行时间测量装置的一示例的结构框图；
图7示出了在时间信号串扰和空间信号串扰影响抽头采样结果的一示例的效果示意图；
图8示出了根据本申请实施例的飞行时间测量方法的一示例的流程图；
图9示出了根据本申请实施例的更新定制探测采样周期所对应的K值的一示例的流程图；
图10示出了根据本申请实施例的飞行时间测量装置的一示例的结构图框图；
图11示出了根据本申请实施例的飞行时间测量方法的一示例的流程图；
图12示出了根据本申请实施例的确定探测采样周期中的各个采样时间区间的一示例的流程图；
图13示出了根据本申请实施例的根据各个灰度信息确定对应待测体的飞行时间的一示例的流程图；
图14示出了根据本申请实施例的飞行时间测量装置的一示例的结构框图；
图15是本申请实施例的电子设备的一示例的示意图。
具体实施方式
以下描述中，为了说明而不是为了限定，提出了诸如特定系统结构、技术之类的具体细节，以便透彻理解本申请实施例。然而，本领域的技术人员应当清楚，在没有这些具体细节的其它实施例中也可以实现本申请。在其它情况中，省略对众所周知的系统、装置、电路以及方法的详细说明，以免不必要的细节妨碍本申请的描述。
为了说明本申请所述的技术方案，下面通过具体实施例来进行说明。
应当理解，当在本说明书和所附权利要求书中使用时，术语“包括”指示所描述特征、整体、步骤、操作、元素和/或组件的存在，但并不排除一个或多个其它特征、整体、步骤、操作、元素、组件和/或其集合的存在或添加。
还应当理解，在此本申请说明书中所使用的术语仅仅是出于描述特定实施例的目的而并不意在限制本申请。如在本申请说明书和所附权利要求书中所使用的那样，除非上下文清楚地指明其它情况，否则单数形式的“一”、“一个”及“该”意在包括复数形式。
还应当进一步理解，在本申请说明书和所附权利要求书中使用的术语“和/或”是指相关联列出的项中的一个或多个的任何组合以及所有可能组合，并且包括这些组合。
如在本说明书和所附权利要求书中所使用的那样，术语“如果”可以依据上下文被解释为“当...时”或“一旦”或“响应于确定”或“响应于检测到”。类似地，短语“如果确定”或“如果检测到[所描述条件或事件]”可以依据上下文被解释为意指“一旦确定”或“响应于确定”或“一旦检测到[所描述条件或事件]”或“响应于检测到[所描述条件或事件]”。
具体实现中，本申请实施例中描述的电子设备包括但不限于诸如具有触摸敏感表面(例如，触摸屏显示器和/或触摸板)的移动电话、膝上型计算机或平板计算机之类的其它便携式设备。还应当理解的是，在某些实施例中，上述设备并非便携式通信设备，而是具有触摸敏感表面(例如，触摸屏显示器)的计算机。
在接下来的讨论中，描述了包括显示器和触摸敏感表面的电子设备。然而，应当理解的是，电子设备可以包括诸如物理键盘、鼠标和/或控制杆的一个或多个其它物理用户接口设备。
可以在电子设备上执行的各种应用程序可以使用诸如触摸敏感表面的至少一个公共物理用户接口设备。可以在应用程序之间和/或相应应用程序内调整和/或改变触摸敏感表面的一个或多个功能以及终端上显示的相应信息。这样，终端的公共物理架构(例如，触摸敏感表面)可以支持具有对用户而言直观且透明的用户界面的各种应用程序。
图1示出了根据本申请实施例的时间飞行深度相机的一示例的结构原理示意图。
如图1所示，时间飞行深度相机10包括发射模块11、接收模块12和控制模块13，控制模块13与发射模块11和接收模块12连接。这里，利用发射模块11可以向待测体20发射光信号(例如，经调制的连续载波光束)102，通过接收模块12可以接收从待测体20反射回的光信号103，通过控制模块13，可以对反射光信号进行计算，从而得到与待测体20之间的距离104。在一些情况下，通过控制模块13还可以调控接收模块12的采样操作，例如调控采样周期或时间等，以满足不同测量场景的需求。
应理解的是，时间飞行深度相机10还可以包括彩色相机、红外相机、IMU等器件，与这些器件的组合可以实现更加丰富的功能，比如3D纹理建模、红外人脸识别、SLAM等功能。
在一些实施方式中，发射模块11可以包括光源(未示出)和光调制器(未示出)，通过光调制器可以控制光源朝向待测体20发射经调制的连续载波光束。此外，接收模块12可以包括由至少一个像素组成的图像传感器，并且每个像素包括多个信号采集组件。这里，信号采集组件可以表示对光信号进行采集的组件，其可以是用于读出和累计电荷的器件，例如信号采集组件可以采用抽头。
具体地，时间飞行深度相机10可以采用间接时间飞行测量方法，并可以通过调制发射光的功率波形为接近正弦波(或其他波形，例如方波)，解调器件(例如传感器，i-TOF Sensor)在不同的时间段对接收光的功率进行能量积分。一般来说，解调器件会有几个不同的采集时间段，这种对回波的正弦信号的分时间段采集等效于对正弦信号进行多点采样。进而，解调器件输出对回波正弦信号的多个采样值，使得控制模块13计算出回波正弦信号的相位延迟，并计算出光信号在时间飞行深度相机10与被测物20之间的飞行距离。
这里，解调的能量积分器件在进行光子积分时，都是共用同一个像素(即光电二极管或其它感光元件)，例如几个不同的读出和电荷累计器件(称为抽头)共同连接这同一个像素，在进行分时采集信号的过程中，不同抽头间的信号增益和暗电流不一致。同时，需要对正弦波信号进行分别对应不同的时间段采样的方式，包含分周期采样(即，一个周期内多个抽头进行采样)和分曝光采样(即，在不同的曝光时间内，分别将抽头的采样时间进行相位延时)。
需说明的是，在分周期采样中，对于一个周期内多个抽头进行分时的分周期采样方法，由于不同抽头的采样干扰因子(例如，增益和暗电流)的不一致性，往往不能准确地计算出光飞行的距离值。此时，通过分曝光的采样方式，将同一抽头进行多次采集，以多次采集的数据进行加减乘除运算，从而消除采样干扰因子项的影响结果，最终达到提高距离测量准确度的目的。
然而，在传统的时间飞行测量系统传感器的解调上，多个抽头的解调时间配置由于算法 的限制，只能选择多个抽头具有相同的能量积分时间(即，在探测周期内具有相等的采样时间长度)。
图2示出了根据CW-iToF技术中多抽头进行电荷积分测距时的一示例的抽头采样信号分布图。
如图2所示，在基于分周期采样方式得到的一帧深度图像之后，还需要基于分曝光采样方式得到的另一帧深度图像，以消除因采样干扰因子所导致的测量误差。
鉴于此，图3示出了根据本申请实施例的飞行时间测量方法的一示例的流程图。关于本申请实施例的执行主体，其可以是各种具有计算或处理功能的测量系统或处理器，例如其可以是时间飞行深度相机10中的控制模块13。
如图3所示，在步骤310中，针对被经调制的连续载波光束照射的待测体，控制多个信号采集组件在一个探测采样周期内顺序启动持续采样时间区间。这里，各个信号采集组件的采样时间区间所对应的时长互异，也就是说，不同的信号采集组件对应采样操作的开始时间点是不一样的，并且不同的信号采集组件所对应的采样时间长度之间也是存在差别的。
示例性地，像素中的各个信号采集组件(也可被称为抽头)可以按照在探测采样周期中不同的时间点顺序开启，并且各个信号采集组件可以具有不同的采样时间长度。举例来说，一个像素中具有四个抽头，可以控制在一次曝光时间内多个抽头在一个探测周期内连续开启且积分采样时间不同，例如假设探测采样周期是T，则抽头A可以是最先被开启的，并且采样时间长度可以是T/8，而抽头B可以是稍后被启动的，并且采样时间长度可以是T/4或其他数值。
需说明的是，各个信号采集组件的采样时间长度可以是非固设的，例如还可以随着不同的业务场景或需求而进行调整。此外，上述的“多个信号采集组件”可以用来表示至少两个信号采集组件，而一般是三个、四个以上。
在步骤320中，针对各个信号采集组件，向信号采集组件施加对应预设的四相位偏移量，以得到相应的灰度信息集。这里，灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应。
示例性地，可以向发射光信号分别施加不同的相位延迟量，并分别调用信号采集组件来采集相应的灰度信息。具体地，可以是在不施加相位延迟时各个抽头分别采集信号完成一帧测量；然后，在施加90度、180度和270度的相位延迟给发射信号后，再分别重复采集相应的测量帧，一共可以得到4帧采样信号。
在步骤330中，根据各个信号采集组件的灰度信息集，确定对应待测体的飞行时间。例如，可以基于预设的在灰度采样信号与飞行时间之间的关系式来进行计算，从而得到对应待 测体的飞行时间，更多细节将在下文中展开。
通过本申请实施例，提出了一种新的时间飞行计算方式，将CW-iToF的一个探测采样周期内的积分计算过程模拟脉冲调制的累积量的过程，使得多个抽头的解调时间不受相同积分采样时间限制，扩展了传感器的适用范围。此外，在计算得到一帧的飞行时间时，需要通过不同的信号采集组件分别测量，相当于多次测量求平均值，还提高了所确定的飞行时间的精确度。
在一些实施方式中，在步骤330之后，测量系统还可以根据针对待测体的飞行时间，确定与待测体之间的距离。
示例性地，可以通过下式来确定测量系统与待测体之间的距离：
Figure PCTCN2022080530-appb-000001
其中，d为与待测体之间的距离，C为光速，t为飞行时间。
图4示出了根据本申请实施例的更新各个信号采集组件的采样时间区间的一示例的流程图。
如图4所示，在步骤410中，获取采样区间设置指令。示例性地，测量系统可以从用户终端接收采样时长设置指令。
在步骤420中，基于采样区间设置指令，更新各个信号采集组件所分别对应的采样时间区间。由此，可以对各个信号采集组件分别设置不同的采样时间区间，并能通过指令交互的方式进行调整，满足了不同用户需求或业务场景的需求。
图5示出了根据本申请实施例的确定对应待测体的飞行时间的一示例的流程图。
如图5所示，在步骤510中，针对各个信号采集组件，基于信号采集组件的采样时间区间和所采集的灰度信息集，确定相应的初始飞行时间。
在步骤520中，基于各个信号采集组件所确定的初始飞行时间，确定对应待测体的飞行时间。这里，可以通过各种统计学方式来综合不同信号采集组件的初始飞行时间，从而得到最终的对应待测体的飞行时间。
示例性地，可以通过多个信号采集组件的初始飞行时间计算相应的平均值，以确定对应待测体的飞行时间。这里，可以直接将相位时间延时作为对应待测体的飞行时间，或者，还可以通过对各个初始飞行时间相对应的平均值进行校准，从而得到相应的飞行时间，以消除一些其他不特定因素所导致的时延。
由此，综合考虑了多个抽头的采样结果，并且各个抽头的采样时间长度不一致，通过针对每个抽头分别得到的飞行时间求平均数，在设计上可以降低针对抽头的采样时间长度的设 计要求，并且能够提升测量精度。
关于上述步骤510的实施细节，可以根据各个灰度信息和预设的初始飞行时间关系式，确定初始飞行时间。这里，初始飞行时间关系式可以是灰度信息与初始飞行时间之间的关联关系。具体地，初始飞行时间关系式可以采用如下式(2)中的示例：
Figure PCTCN2022080530-appb-000002
其中，t′ A表示信号采集组件A所对应的初始飞行时间，T表示探测采样周期，信号采集组件A的采样时间区间为[0,3/4T]，以及I A,0、
Figure PCTCN2022080530-appb-000003
和
Figure PCTCN2022080530-appb-000004
表示信号采集组件A在相位偏移量分别为0、1/4T、2/4T和3/4T时所对应的灰度信息。
针对如上述式(2)，将在下文中详细描述相应的推导过程。
需说明的是，时间飞行测量系统是基于光电转换器件的成像设备，其本质上还是光子能量积分器件，而抽头作为读出和储存元件，其内部有放大电路和暗电流噪声。然而目前，抽头所采集的光能量是积累的光电荷，而并未进行量化，在本文中，可以使用入射光子数表征抽头采集的光能量。
具体地，成像的灰度值I(其也可以写作抽头采集的光能量)与入射光子数C Signal,Photon、抽头增益G、暗电流C Dark,Electron之间的关系为：
I＝G(C Signal,Photon+C Dark,Electron)      (3)
这里，抽头所输出灰度值I所表征的是像素采集的电荷量，是光入射到像素上发射光电效应产生电荷，也可以被定义为采集光子数。
以二抽头传感器为例，两个抽头A、B采样的灰度值分别为：
Figure PCTCN2022080530-appb-000005
Figure PCTCN2022080530-appb-000006
两个抽头采集到的灰度值形成了对正弦曲线的两点采样。其中，抽头接收到的信号光子数是入射光子数时间分布的积分：
Figure PCTCN2022080530-appb-000007
其中，T可以表示调制周期(即，探测采样周期)，a表示接收光子数随时间变化的振幅，t 0为单周期内抽头开始积分的时间，Δt为抽头在单周期内的积分时间(即，采样时间长度)，t'为波形光飞行时间造成的固定相位延时，ρ (Ambient,Photon)表示环境光子时间密度，以 及
Figure PCTCN2022080530-appb-000008
为与t 0、Δt和T有关的常数，其是光子数积分的中间过程得到的一个表征量。重复N个探测周期的积累即可完成一次曝光，采集一个子帧。
在本申请实施例中，调制的连续载波光束为正弦波，当然也可以将其替换为方波等其他波形。这里，仅以两抽头传感器为例进行说明，其也可以是3抽头、4抽头等等。在一个探测周期内两抽头连续开启且积分采样时间互不相同，两个抽头的积分时间可以任意设置，例如抽头A、B分别设置为3T/4、T/4；即在一个探测周期内，抽头A的积分采样时间(即，采样时间区间)为0到3T/4，抽头B的积分采样时间为3T/4到T；当Δt＝3T/4时，
Figure PCTCN2022080530-appb-000009
而当Δt＝T/4时，
Figure PCTCN2022080530-appb-000010
那么，两个抽头A和B积分后所采集到的光子数为：
Figure PCTCN2022080530-appb-000011
Figure PCTCN2022080530-appb-000012
其中，t A、t B分别为两个抽头开始采集的时间，分别为0和3T/4。进而有
Figure PCTCN2022080530-appb-000013
Figure PCTCN2022080530-appb-000014
需说明的是，若要依据两个抽头采集到的灰度值I A和I B计算光飞行时间等因素造成的时间延迟t'，则需要对不同抽头的增益和暗电流所导致的误差进行消除，并可以通过采集多个相位延迟下同一个抽头的采样数据。
示例性地，在分曝光采样过程中，可以对各个抽头分别进行四次相位延迟曝光采集操作，即t A分别取0、T/4、2T/4和3T/4时进行四次曝光。需说明的是，在本申请实施例的分曝光采样过程中采用了四次曝光，并且曝光相位延迟固定，与传统的四相位采样方式截然不同。
以抽头A为例，经过四次延迟曝光，可以得到：
Figure PCTCN2022080530-appb-000015
Figure PCTCN2022080530-appb-000016
Figure PCTCN2022080530-appb-000017
Figure PCTCN2022080530-appb-000018
其中，根据相位延迟Φ与时间延迟t’之间的关系，可以得到：
Figure PCTCN2022080530-appb-000019
因此，通过首先定义了抽头输出灰度值的计算表达式，可以求出每个抽头每帧输出的灰度值，再结合四次曝光获得四相位延迟曝光下分别采集的灰度值I，得到相位延迟与时间延迟的关系，又由于相位延迟与四相位灰度值的关系
Figure PCTCN2022080530-appb-000020
可以计算各个抽头的时间延迟。
那么，光飞行时间等因素造成的时间延迟t’，为：
Figure PCTCN2022080530-appb-000021
Figure PCTCN2022080530-appb-000022
Figure PCTCN2022080530-appb-000023
通过上述分曝光采样过程中，对各个抽头分别进行四次相位延迟曝光采集操作，并分别利用不同相位的灰度采集结果和相应的采样时间区间计算各自的时间延时，并将各个时间延时进行平均化而最终得到精确度较高的相位延时。
需说明的是，除了直接利用上述初始飞行时间关系式来计算与灰度信息相应的初始飞行时间之外，还可以通过其他方式来计算初始飞行时间。示例性地，针对信号采集组件A中的各个灰度信息，可以确定与该灰度信息对应的相位偏移信息关系式。这里，相位偏移信息关系式可以是包含初始飞行时间变量且用来表示相位偏移信息的关系式。
例如，可以借鉴如上文中针对式(9)的描述，信号采集组件A经过延迟曝光后所产生的相位延迟，可以使用如下的相位偏移信息关系式进行表示：
Figure PCTCN2022080530-appb-000024
其中，φ A可以表示信号采集组件A所对应的相位偏移信息。
接着，可以根据各个灰度信息，确定相应的相位偏移信息。应理解的是，相位偏移信 息与不同偏移量的灰度信息之间存在固有关系，其可以被表示为：
Figure PCTCN2022080530-appb-000025
进而，可以将上述两个关于φ A的因式进行组合，求解出t A′，得到信号采集组件A所对应的初始飞行时间。
在本申请实施例中，将抽头的积分时间不进行限制，同样可以解算出来光的飞行时间，使得多个抽头的解调时间不受相同的积分时间限制，扩展了时间飞行测量系统传感器的适用范围。
图6示出了根据本申请实施例的飞行时间测量装置的一示例的结构框图。
如图6所示，飞行时间测量装置600包括信号采集组件启动单元610、偏移灰度采样单元620和飞行时间确定单元630。
信号采集组件启动单元610被配置为针对被经调制的连续载波光束照射的待测体，控制多个信号采集组件在一个探测采样周期内顺序开启且各自具有长度互异的采样时间区间。
偏移灰度采样单元620被配置为针对各个所述信号采集组件，获取所述信号采集组件对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与四相位偏移量中不同的相位偏移量相对应。
飞行时间确定单元630被配置为根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间。
需要说明的是，上述装置/单元之间的信息交互、执行过程等内容，由于与本申请方法实施例基于同一构思，其具体功能及带来的技术效果，具体可参见方法实施例部分，此处不再赘述。
关于本申请实施例的另一方面，需说明的是，目前的时间飞行测量系统还存在一些需要进行改进的地方。一般来说，解调的能量积分器件在进行光子积分时，都是共用同一个像素(即光电二极管或其它感光元件)，不同的读出和电荷累计器件(称为抽头)共同连接这同一个像素，在进行分时采集信号的过程中，难免出现不同抽头之间出现接收电荷信号的时间上的串扰和空间上的串扰。
图7示出了在时间信号串扰和空间信号串扰影响抽头采样结果的一示例的效果示意图。
这里，时间信号串扰是指，由于像素的空间面积和抽头的离散空间分布，如图7所示，部分在第一个抽头开启采集时产生的电荷信号由于空间距离，并没有进入该抽头；转而在下一个抽头开启采集时，进入到下一个抽头中生成信号。另外，空间上的串扰是指，当某一个 抽头开启电荷采集时，指向开启电荷采集的抽头电势场梯度升高，指向未开启电荷采集的抽头电势场梯度降低；然而，即使未开启电荷采集的抽头电势场梯度低，然而如图7所示，由于电荷的布朗运动，仍然会有像素中接近未开启抽头位置的信号电荷进入到未开启抽头中，产生空间信号串扰。因此，时间串扰和空间串扰在测量中都是一种噪声，会影响测量精度。
鉴于此，图8示出了根据本申请实施例的飞行时间测量方法的一示例的流程图。关于本申请实施例的执行主体，其可以是各种具有计算或处理功能的测量系统或处理器，例如其可以是时间飞行深度相机10中的控制模块13。
如图8所示，在步骤810中，针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间。这里，定制探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个信号采集组件的采样时间区间长度为(K/M)*T。因此，将信号采集组件的采样时间区间扩展了K倍。
这里，定制探测采样周期中包含多个原始探测采样周期(例如，正弦波周期)，扩大了探测周期，为扩展每一信号采集组件的采样时间长度铺垫了基础。
在步骤820中，获取各个信号采集组件分别对应预设的四相位偏移量的灰度信息集。这里，灰度信息集中的各个灰度信息分别与四相位偏移量中不同的相位偏移量相对应。
在步骤830中，根据各个信号采集组件的灰度信息集，确定对应待测体的飞行时间。
通过本申请实施例，在不影响时间飞行测量传感器的测量功能前提下，提出一种新的抽头解调方式，在无法改变串扰光子数的条件下，增加各个抽头的能量积分时间，使得串扰光子相对于信号光子降低，提升了信号的信噪比。
在一些实施方式中，在步骤830之后，该方法还包括：根据对应待测体的飞行时间，确定与待测体之间的距离，例如，将飞行时间代入上述式(1)，从而得到相对于待测体的距离。
关于上述步骤830的实施细节，可以部分参照或参考上文中结合图5的描述。具体地，测量系统可以针对各个信号采集组件，基于信号采集组件的采样时间区间和所采集的灰度信息集，确定相应的初始飞行时间。进而，基于各个信号采集组件所确定的初始飞行时间，确定对应待测体的飞行时间。示例性地，可以计算与多个信号采集组件的初始飞行时间相对应的平均值，以确定对应待测体的飞行时间。
图9示出了根据本申请实施例的更新定制探测采样周期所对应的K值的一示例的流程图。
如图9所示，在步骤910中，获取定制探测采样周期设置指令。示例性地，测量系统可以从用户终端接收定制探测采样周期设置指令。
在步骤920中，基于定制探测采样周期设置指令，更新定制探测采样周期的K值。由此，可以针对信号采集组件定制具有扩展时间长度的探测采样周期，并能通过指令交互的方式进行调整，满足了不同用户需求或业务场景的需求。
具体地，可以通过以下方式来确定相应的初始飞行时间：
Figure PCTCN2022080530-appb-000026
其中，t′ A表示信号采集组件A所对应的初始飞行时间，定制探测采样周期为3T，四抽头传感器中信号采集组件A的采样区间时间为[0,3/4T]，以及I A,0、
Figure PCTCN2022080530-appb-000027
和
Figure PCTCN2022080530-appb-000028
表示信号采集组件A在相位偏移量分别为0、1/4T、2/4T和3/4T时所对应的灰度信息。
下文将以四抽头传感器为例来详细描述针对式(11)的推导细节。应理解的是，在本申请实施例中，也还可以采用两抽头传感器，即两个抽头在一个定制探测周期中具有相等的采样时间长度。
这里，在测量系统的具体解调过程中，其可以采用分周期采样方式和分曝光采样方式进行解调。关于上述式(11)的推导过程，可以部分参照上文针对式(2)的推导细节。
当采用原始的正弦波周期T作为探测采样周期时，四抽头传感器中的各个抽头A、B、C、D的积分时间均为T/4，其所对应的时间延迟分别为：
Figure PCTCN2022080530-appb-000029
Figure PCTCN2022080530-appb-000030
Figure PCTCN2022080530-appb-000031
Figure PCTCN2022080530-appb-000032
那么，因光飞行时间等因素所造成的时间延迟t’为：
Figure PCTCN2022080530-appb-000033
一般来说，四个抽头采集一个周期的信号，使得当Δt＝T/4时，
Figure PCTCN2022080530-appb-000034
但是，由于时间串扰和空间串扰的存在，串扰的光子是噪声干扰信号，且串扰光子数占单个周期内的 光子数的比例一定，每一个探测周期内都存在一定量的串扰。为了减小串扰光子对信号光子的干扰，在本申请实施例中提出，在总的探测周期数保持不变的情况下，可以将四抽头传感器中四个抽头所采集积分时间增加，即四个抽头的积分时间总和对应多个探测周期，使得信号光子数大大增加，而串扰光子数维持不变，可以大幅提高信噪比。
在本申请实施例的一些示例中，可以将K个原始探测采样周期T合为一个定制探测采样周期，对于每个抽头来说，原始的采样时间长度为T/4，而通过扩展周期后的采样时间长度变为KT/4。
这里，抽头数M与对应定制采样周期中所包含的原始采样周期T的数量K之间应满足下式：
Figure PCTCN2022080530-appb-000035
其中，s表示整数。
例如，可以将定制探测采样周期中的原始采样周期的数量K设置为3，此时四个抽头开始采集的时间t A、t B、t C、t D分别为0、
Figure PCTCN2022080530-appb-000036
完成分周期采样操作。进而，对每个抽头分别进行四次相位延迟曝光采集，t A分别取0、
Figure PCTCN2022080530-appb-000037
进行四次曝光。
那么，光飞行时间等因素造成的时间延迟t’为：
Figure PCTCN2022080530-appb-000038
Figure PCTCN2022080530-appb-000039
Figure PCTCN2022080530-appb-000040
Figure PCTCN2022080530-appb-000041
Figure PCTCN2022080530-appb-000042
由此，即使扩展不同抽头的采样时间长度，也可以通过上述关系式来完成时间飞行计算操作。同时，由于单个抽头积分的信号光子增多，而串扰光子总数不变，使得信号的信噪比相对增大，实现测量精度的提升。
图10示出了根据本申请实施例的飞行时间测量装置的一示例的结构框图。
如图10所示，飞行时间测量装置1000包括信号采集组件启动单元1010、偏移灰度采样单元1020和飞行时间确定单元1030。
信号采集组件启动单元1010被配置为针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间，其中所述定制探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个所述信号采集组件的采样时间区间长度为(K/M)*T。
偏移灰度采样单元1020被配置为获取各个所述信号采集组件分别对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应；
飞行时间确定单元1030被配置为根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间。
需要说明的是，上述装置/单元之间的信息交互、执行过程等内容，由于与本申请方法实施例基于同一构思，其具体功能及带来的技术效果，具体可参见方法实施例部分，此处不再赘述。
关于本申请实施例的又一方面，需说明的是，目前的时间飞行测量系统还存在一些需要进行改进的地方。对于一个像素对应多个抽头的传感器来说，由于同一个像素需要多个读出电路，例如参照图7中抽头传感器的示例，像素的体积将受到读出电路的限制而不能做到很小，这将大大限制传感器的像素分辨率；同时，多个分时电路的设计和制造难度较大。
鉴于此，图11示出了根据本申请实施例的飞行时间测量方法的一示例的流程图。关于本申请实施例的执行主体，其可以是各种具有计算或处理功能的测量系统或处理器，例如其可以是时间飞行深度相机10中的控制模块13。
如图11所示，在步骤1110中，针对被经调制的连续载波光束照射的待测体，控制单个信号采集组件在探测采样周期内启动采样时间区间。
需说明的是，抽头的采样时间长度为可以任意或按需求进行设置，例如当设置为3T/4时，抽头可以不再采集对应剩下的T/4的输入的能量，并可以将这部分能量直接引出，忽略不计。
在步骤1120中，获取信号采集组件对应预设的四相位偏移量的各个灰度信息。
示例性地，可以向像素中的单抽头分别施加多个相位偏移量，并分别进行多次曝光使该抽头记录相应的多个采样值，以完成分曝光采样操作。
在步骤1130中，根据各个灰度信息，确定对应待测体的飞行时间。
需说明的是，由于目前相关技术中由抽头采集的能量在完成采集后会输出到后面的电路中进行处理，导致时耗且对抽头的容量也有较高要求，并也不能保证测量结果的准确度。然而，在本申请实施例中，可以利用单个抽头，直接计算出相应的飞行时间。
由此，在不影响时间飞行测量传感器的测量功能前提下，通过采用单抽头的像素布局，可以降低芯片设计和加工难度，降低了单像素的面积，并提高传感器的分辨率。
在一些实施方式中，在步骤830之后，该方法还包括：根据对应待测体的飞行时间，确定与待测体之间的距离，例如，将飞行时间代入上述式(1)，从而得到相对于待测体的距离。
图12示出了根据本申请实施例的确定探测采样周期中的各个采样时间区间的一示例的流程图。
如图12所示，在步骤1210中，获取采样时间区间设置指令。示例性地，测量系统可以从用户终端接收采样时间区间设置指令。
在步骤1220中，根据采样时间区间设置指令，确定探测采样周期中的各个采样时间区间。由此，可以对信号采集组件中设置不同的采样时间区间，包括各个采样阶段的开始时间和相应的采样时间长度，能通过指令交互的方式进行调整，满足了不同用户需求或业务场景的需求。
关于上述步骤1130的具体实施细节，一方面，可以根据各个灰度信息和预设的飞行时间关系式，确定对应待测体的飞行时间。这里，飞行时间关系式为灰度信息与飞行时间之间的关联关系。由此，测量系统可以利用在不同偏移量下的灰度信息直接代入关系式进行计算，快速得出相应的飞行时间。
在一些实施方式中，可以通过以下方式来确定相应的飞行时间：
Figure PCTCN2022080530-appb-000043
其中，t’表示对应待测体的飞行时间，信号采集组件的单次采样区间时间长度为1/4T，以及I A,0、
Figure PCTCN2022080530-appb-000044
和
Figure PCTCN2022080530-appb-000045
表示信号采集组件A在相位偏移量分别为0、1/4T、2/4T和3/4T时所对应的灰度信息。
这里，在测量系统的具体解调过程中，其可以采用分周期采样方式和分曝光采样方式进行解调。关于上述式(16)的推导过程和细节，还可以部分参照上文中其他相关部分的描述。
关于上述步骤1130的具体实施细节，另一方面，还可以参照如图12的流程中的操作。 图13示出了根据本申请实施例的根据各个灰度信息确定对应待测体的飞行时间的一示例的流程图。
如图13所示，在步骤1310中，针对各个灰度信息，确定与灰度信息对应的相位偏移信息关系式。这里，相位偏移信息表达式为包含飞行时间变量的关系式。
在步骤1320中，根据各个灰度信息，确定相应的相位偏移信息。
在步骤1330中，根据相位偏移信息与相位偏移信息关系式，求解飞行时间变量，以得到对应所述待测体的飞行时间。
示例性地，可以借鉴如上文中针对式(9)的描述，单抽头经过延迟曝光后所产生的相位延迟，可以使用如下的相位偏移信息关系式进行表示：
Figure PCTCN2022080530-appb-000046
此时，可以计算相应的相位偏移信息为：
Figure PCTCN2022080530-appb-000047
进而，可以将上述两个关于Φ的因式进行组合，求解出t’，得到光飞行时间。
由此，首先定义了抽头输出灰度值的光子数计算表达式，可以求出抽头每帧输出的灰度值，再结合多次曝光获得四相位延迟(例如，相位延迟分别取0，T/4、2T/4和3T/4)曝光下分别采集的灰度值，得到相位延迟与时间延迟的关系，并将相位延迟与四相位灰度值的固有关系综合考虑，可以计算抽头的时间延迟。
在本申请实施例中，在一个像素中可以只做一个读出电路(即像素只有一个抽头)，通过调控该抽头的开始读出时间与结束读出时间，来模拟在多抽头传感器的采样解调过程，依然能够得到较精确的测量结果。由于单个像素只做一个抽头，大大降低了电路设计的难度；同时减小了单像素的面积，使得像素可以做很小，从而提高时间飞行测量芯片的分辨率。
图14示出了根据本申请实施例的飞行时间测量装置的一示例的结构框图。
如图14所示，飞行时间测量装置1400包括信号采集组件启动单元1410、偏移采样单元1420和飞行时间确定单元1430。
信号采集组件启动单元1410被配置为针对被经调制的连续载波光束照射的待测体，控制单个信号采集组件在探测采样周期内连续启动多个采样时间区间，其中各个所述采样时间区间具有相等的采样时间区间长度。
偏移采样单元1420被配置为获取所述信号采集组件对应预设的四相位偏移量的各个灰度信息。
飞行时间确定单元1430被配置为根据各个所述灰度信息和所述采样时间区间长度，确定对应所述待测体的飞行时间。
需要说明的是，上述装置/单元之间的信息交互、执行过程等内容，由于与本申请方法实施例基于同一构思，其具体功能及带来的技术效果，具体可参见方法实施例部分，此处不再赘述。
图15是本申请实施例的电子设备的一示例的示意图。如图15所示，该实施例的电子设备1500包括：处理器1510、存储器1520以及存储在所述存储器1520中并可在所述处理器1510上运行的计算机程序1530。所述处理器1510执行所述计算机程序1530时实现上述飞行时间测量方法实施例中的步骤，例如图3所示的步骤310至330，或者步骤810至步骤830，或者步骤1110至1130。或者，所述处理器1510执行所述计算机程序1530时实现上述各装置实施例中各模块/单元的功能，例如图6所示单元610至630的功能，或者如图10所示的单元1010至1030，或者如图14所示的单元1410至1430。
示例性的，所述计算机程序1530可以被分割成一个或多个模块/单元，所述一个或者多个模块/单元被存储在所述存储器1520中，并由所述处理器1510执行，以完成本申请。所述一个或多个模块/单元可以是能够完成特定功能的一系列计算机程序指令段，该指令段用于描述所述计算机程序1530在所述电子设备1500中的执行过程。
在本申请实施例的一个示例中，所述计算机程序1530可以被分割成信号采集组件启动程序模块、偏移灰度采样程序模块和飞行时间确定程序模块，各程序模块具体功能如下：
信号采集组件启动程序模块，被配置为针对被经调制的连续载波光束照射的待测体，控制多个信号采集组件在一个探测采样周期内顺序开启且各自具有长度互异的采样时间区间；
偏移灰度采样程序模块，被配置为针对各个所述信号采集组件，获取所述信号采集组件对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与四相位偏移量中不同的相位偏移量相对应；
飞行时间确定程序模块，被配置为根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间。
在本申请实施例的另一示例中，所述计算机程序1530可以被分割成信号采集组件启动程序模块、偏移灰度采样程序模块和飞行时间确定程序模块，各程序模块具体功能如下：
信号采集组件启动程序模块，被配置为针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间，其中所述定制 探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个所述信号采集组件的采样时间区间长度为(K/M)*T；
偏移灰度采样程序模块，被配置为获取各个所述信号采集组件分别对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应；
飞行时间确定程序模块，被配置为根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间。
在本申请实施例的另一示例中，所述计算机程序1530可以被分割成信号采集组件启动程序模块、偏移采样程序模块和飞行时间确定程序模块，各程序模块具体功能如下：
信号采集组件启动程序模块，被配置为针对被经调制的连续载波光束照射的待测体，控制单个信号采集组件在探测采样周期内启动采样时间区间；
偏移采样程序模块，被配置为获取所述信号采集组件对应预设的四相位偏移量的各个灰度信息；
飞行时间确定程序模块，被配置为根据所述各个灰度信息，确定对应所述待测体的飞行时间。
所述电子设备1500可以是桌上型计算机、笔记本、掌上电脑及云端服务器等计算设备。所述电子设备可包括，但不仅限于，处理器1510、存储器1520。本领域技术人员可以理解，图15仅是电子设备1500的示例，并不构成对电子设备1500的限定，可以包括比图示更多或少的部件，或组合某些部件，或不同的部件，例如所述电子设备还可以包括输入输出设备、网络接入设备、总线等。
所称处理器1510可以是中央处理单元(Central Processing Unit，CPU)，还可以是其他通用处理器、数字信号处理器(Digital Signal Processor，DSP)、专用集成电路(Application Specific Integrated Circuit，ASIC)、现场可编程门阵列(Field-Programmable Gate Array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
所述存储器1520可以是所述电子设备1500的内部存储单元，例如电子设备1500的硬盘或内存。所述存储器1520也可以是所述电子设备1500的外部存储设备，例如所述电子设备1500上配备的插接式硬盘，智能存储卡(Smart Media Card,SMC)，安全数字(Secure Digital,SD)卡，闪存卡(Flash Card)等。进一步地，所述存储器1520还可以既包括所述电子设备1500的内部存储单元也包括外部存储设备。所述存储器1520用于存储所述计算机程序以及所述电子设备所需的其他程序和数据。所述存储器1520还可以用于暂时地存储已经输出或 者将要输出的数据。
所属领域的技术人员可以清楚地了解到，为了描述的方便和简洁，仅以上述各功能单元、模块的划分进行举例说明，实际应用中，可以根据需要而将上述功能分配由不同的功能单元、模块完成，即将所述装置的内部结构划分成不同的功能单元或模块，以完成以上描述的全部或者部分功能。实施例中的各功能单元、模块可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中，上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。另外，各功能单元、模块的具体名称也只是为了便于相互区分，并不用于限制本申请的保护范围。上述系统中单元、模块的具体工作过程，可以参考前述方法实施例中的对应过程。
在上述实施例中，对各个实施例的描述都各有侧重，某个实施例中没有详述或记载的部分，可以参见其它实施例的相关描述。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
在本申请所提供的实施例中，应该理解到，所揭露的装置/电子设备和方法，可以通过其它的方式实现。例如，以上所描述的装置/电子设备实施例仅仅是示意性的，例如，所述模块或单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通讯连接可以是通过一些接口，装置或单元的间接耦合或通讯连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述单元既可以采用硬件的形式实现，也可以采用软件的形式实现。
所述集成的模块/单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请实现上述实施例方法中的全部或部分流程，也可以通过计算机程序来指令相关的硬件来完成，所述的计算机程序可 存储于一计算机可读存储介质中，该计算机程序在被处理器执行时，可实现上述各个方法实施例的步骤。其中，所述计算机程序包括计算机程序代码，所述计算机程序代码可以为源代码形式、对象代码形式、可执行文件或某些中间形式等。所述计算机可读介质可以包括：能够携带所述计算机程序代码的任何实体或装置、记录介质、U盘、移动硬盘、磁碟、光盘、计算机存储器、只读存储器(ROM，Read-Only Memory)、随机存取存储器(RAM，Random Access Memory)、电载波信号、电信信号以及软件分发介质等。需要说明的是，所述计算机可读介质包含的内容可以根据司法管辖区内立法和专利实践的要求进行适当的增减，例如在某些司法管辖区，根据立法和专利实践，计算机可读介质不包括电载波信号和电信信号。
以上所述实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围，均应包含在本申请的保护范围之内。

Claims (10)

  1. 一种飞行时间测量方法，其特征在于，包括：
    针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间，其中所述定制探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个所述信号采集组件的采样时间区间长度为(K/M)*T；
    获取各个所述信号采集组件分别对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应；
    根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间。
  2. 如权利要求1所述的方法，其特征在于，根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间，包括：
    针对各个所述信号采集组件，基于所述信号采集组件的采样时间区间和所采集的灰度信息集，确定相应的初始飞行时间；
    基于各个所述信号采集组件所确定的初始飞行时间，确定对应所述待测体的飞行时间。
  3. 如权利要求2所述的方法，其特征在于，所述基于各个所述信号采集组件所确定的初始飞行时间，确定对应所述待测体的飞行时间，包括：
    计算与所述多个信号采集组件的初始飞行时间相对应的平均值，以作为对应所述待测体的飞行时间。
  4. 如权利要求1所述的方法，其特征在于，所述方法还包括通过以下方式来确定相应的初始飞行时间：
    Figure PCTCN2022080530-appb-100001
    其中，t′ A表示信号采集组件A所对应的初始飞行时间，定制探测采样周期为3T，四抽头传感器中信号采集组件A的采样区间时间为[0,3/4T]，以及I A,0、
    Figure PCTCN2022080530-appb-100002
    和
    Figure PCTCN2022080530-appb-100003
    表示信号采集组件A在相位偏移量分别为0、1/4T、2/4T和3/4T时所对应的灰度信息。
  5. 如权利要求1所述的方法，其特征在于，所述方法还包括：
    获取定制探测采样周期设置指令；
    基于所述定制探测采样周期设置指令，更新所述定制探测采样周期的所述K值。
  6. 如权利要求1或5所述的方法，其特征在于，所述K值满足以下条件：
    Figure PCTCN2022080530-appb-100004
    其中，s表示整数。
  7. 一种飞行时间测量装置，其特征在于，包括：
    信号采集组件启动单元，被配置为针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间，其中所述定制探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个所述信号采集组件的采样时间区间长度为(K/M)*T；
    偏移灰度采样单元，被配置为获取各个所述信号采集组件对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应；
    飞行时间确定单元，被配置为根据各个所述信号采集组件的灰度信息集，确定对应所述待测体的飞行时间。
  8. 一种时间飞行深度相机，其特征在于，包括：
    发射模块，包括光源和光调制器，所述光调制器用于控制所述光源朝向待测体发射经调制的连续载波光束；
    接收模块，包括由至少一个像素组成的图像传感器，每个所述像素包括多个信号采集组件，用于接收从所述待测体反射回的光信号；
    控制模块，与发射模块和接收模块连接，并被配置为：
    针对被经调制的连续载波光束照射的待测体，控制M个信号采集组件在定制探测采样周期内顺序启动持续采样时间区间，其中所述定制探测采样周期包括K个原始探测采样周期T，M和K均为大于1的正整数，以及各个所述信号采集组件的采样时间区间长度为(K/M)*T；
    获取各个所述信号采集组件分别对应预设的四相位偏移量的灰度信息集，其中所述灰度信息集中的各个灰度信息分别与不同的相位偏移量相对应；
    根据各个所述信号采集组件的采样时间区间和相应的灰度信息集，确定对应所述待测 体的飞行时间。
  9. 一种电子设备，包括存储器、处理器以及存储在所述存储器中并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现如如权利要求1-6中任一项所述方法的步骤。
  10. 一种计算机可读存储介质，所述计算机可读存储介质存储有计算机程序，所述计算机程序被处理器执行时实现如权利要求1-6中任一项所述方法的步骤。
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