CN111580074B - Time precision calibration method and device and electronic equipment - Google Patents
Time precision calibration method and device and electronic equipment Download PDFInfo
- Publication number
- CN111580074B CN111580074B CN202010456077.5A CN202010456077A CN111580074B CN 111580074 B CN111580074 B CN 111580074B CN 202010456077 A CN202010456077 A CN 202010456077A CN 111580074 B CN111580074 B CN 111580074B
- Authority
- CN
- China
- Prior art keywords
- time
- digital converter
- pulses
- time period
- acquisition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- G01S7/497—Means for monitoring or calibrating
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
- G01S17/14—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The application relates to a time precision calibration method, a time precision calibration device and electronic equipment, wherein pulse signals received in each sampling period time are uniformly distributed by controlling a time-to-digital converter, when the pulse signals acquired in each acquisition time period reach a target number, the actual pulse number, the theoretical pulse number and the total pulse number acquired in the sampling period time are acquired, the accumulated deviation value of the pulse numbers is further acquired, and finally, the minimum distance measurement time precision is calibrated according to the accumulated deviation value, so that the time measurement precision of a flight time module is improved. Because the pulse signals are uniformly distributed in the sampling period time of the time-to-digital converter, the number of the pulse signals in each acquisition time period can reflect the time length of each minimum ranging time precision, so that the minimum ranging time precision can be calibrated by accumulating deviation values of the number of the pulses, and the time measurement precision can be effectively improved without introducing complicated test instrument equipment.
Description
Technical Field
The invention relates to the field of time-of-flight ranging, in particular to a time precision calibration method, a time precision calibration device and electronic equipment.
Background
A Direct Time of flight (dTof) ranging system utilizes a Time-to-Digital Converter (TDC) to perform sampling and calculation of a Time dimension, and the Time measurement accuracy of the TDC directly affects the distance measurement accuracy of the dTof system.
However, due to electronic non-linearity, the time accuracy between TDCs varies. The minimum ranging time accuracy of each TDC can be determined by the Least Significant Bit (LSB) of the Least Significant Bit, and the actual minimum ranging time accuracy has a slight difference from the LSB of each TDC. Therefore, in a ranging period, the difference between the actual minimum ranging precision and the LSB is accumulated, so that the difference between the flight time acquired by the finally obtained TDC and the real time difference generate deviation, and the actual test distance and the real value generate deviation.
Therefore, in the existing time-of-flight system related to the time measurement of the TDC, the system has the problem of inaccurate time measurement and finally inaccurate system ranging distance due to the deviation of the minimum time precision of the TDC.
Disclosure of Invention
The application provides a time precision calibration method, a time precision calibration device and electronic equipment, which can calibrate the minimum ranging time precision of a TDC, thereby improving the time measurement precision of the TDC and improving the accuracy of a measurement result.
A method of time accuracy calibration, the method being based on a time-of-flight module comprising a photodetector and a time-to-digital converter that collects a pulse signal detected by the photodetector; the method comprises the following steps:
under a preset condition, controlling the pulse signals received by the time-to-digital converter within a sampling time period to be uniformly distributed; each sampling time period is divided into a plurality of acquisition time periods, and each acquisition time period corresponds to the actual time length of sampling the minimum ranging time precision each time by the time-to-digital converter;
when the pulse signals acquired by the time-to-digital converter in each acquisition time period reach a target number, acquiring the actual number of pulses acquired by the time-to-digital converter in each acquisition time period and the total number of pulses acquired by the sampling period;
acquiring the theoretical number of pulses of the acquisition time period according to the number of the sections of the acquisition time period and the total number of pulses contained in the time-to-digital converter;
acquiring an accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses;
calibrating the minimum ranging time accuracy in each sampling period of the time to digital converter according to the accumulated deviation value.
In one embodiment, the photodetector is a single photon detector, and dark noise generated inside the photodetector is subject to statistical randomness.
In one embodiment, the step of controlling the pulse signal received by the time-to-digital converter within the sampling time period to be uniformly distributed under a preset condition comprises:
under the condition of a darkroom, the dark noise of the single-photon detector is used as a pulse signal source;
and controlling the single-photon detector to run to a first target time so that the pulse signals received by the time-to-digital converter in a sampling time period are uniformly distributed.
In one embodiment, the photodetector is a linear detector; under a preset condition, the step of controlling the pulse signal received by the time-to-digital converter in a sampling time period to be uniformly distributed comprises the following steps:
providing a direct current light source and an irradiated plane, wherein reflected light irradiated on the irradiated plane by the direct current light source is used as a detection light source of the linear detector, and the irradiation field angle of the direct current light source irradiated on the irradiated plane is larger than the receiving field angle of the time-of-flight module;
and controlling the linear detector to receive the optical signal of the reflected light and operate to a second target time so as to enable the pulse signal received by the time-to-digital converter in a sampling time period to be uniformly distributed.
In one embodiment, the illuminated plane is a lambertian plane.
In one embodiment, when the pulse signals acquired by the time-to-digital converter in each acquisition time period reach a target number, the step of obtaining the actual number of pulses acquired by the time-to-digital converter in each acquisition time period and the total number of pulses acquired by the time-to-digital converter in each sampling period includes:
when the pulse signals acquired by the time-to-digital converter in each acquisition time period reach a target number, taking the number of pulses acquired by each acquisition time period counted currently as the actual number of pulses acquired by each acquisition time period in one sampling period time;
and acquiring the total number of pulses of one sampling period according to the actual number of pulses acquired in each acquisition time period.
In one embodiment, the step of obtaining an accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses includes:
acquiring a deviation value of each acquisition time period relative to the theoretical pulse number according to the actual pulse number and the theoretical pulse number;
and accumulating the deviation value of each acquisition time period to obtain the accumulated deviation value.
A time accuracy calibration device is based on a time-of-flight module, wherein the time-of-flight module comprises a photoelectric detector and a time-to-digital converter, and the time-to-digital converter collects pulse signals detected by the photoelectric detector; the device comprises:
the control module is used for controlling the pulse signals received by the time-to-digital converter within a sampling time period to be uniformly distributed under a preset condition; each sampling time period is divided into a plurality of acquisition time periods, and each acquisition time period corresponds to the actual time length of sampling the minimum ranging time precision each time by the time-to-digital converter;
a first obtaining module, configured to obtain an actual number of pulses collected by the time-to-digital converter in each collection time period and a total number of pulses collected by the sampling cycle time when pulse signals collected by the time-to-digital converter in each collection time period reach a target number;
the second acquisition module is used for acquiring the theoretical number of pulses of the acquisition time period according to the number of the sections of the acquisition time period and the total number of pulses contained in the time-to-digital converter;
the third acquisition module is used for acquiring the accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses;
and the calibration module is used for calibrating the minimum ranging time precision in each sampling period of the time-to-digital converter according to the accumulated deviation value.
An electronic device comprises a time-of-flight module, a memory and a processor, wherein the memory stores a computer program, the time-of-flight module comprises a photoelectric detector and a time-to-digital converter and is connected with the processor, and the steps of the method are realized when the processor executes the computer program.
A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the above-mentioned method.
According to the time precision calibration method, the time precision calibration device, the electronic equipment and the computer readable storage medium, the pulse signals received by the time-to-digital converter within each sampling period are uniformly distributed, when the pulse signals acquired by the time-to-digital converter within each acquisition time period reach the target number, the actual number of pulses acquired by the time-to-digital converter within each acquisition time period and the total number of pulses acquired by the sampling period are acquired, further, the theoretical number of pulses within the acquisition time period is acquired, the accumulated deviation value of the number of pulses is acquired according to the actual number of pulses and the theoretical number of pulses, and finally, the minimum distance measurement time precision is calibrated according to the accumulated deviation value, so that the time measurement precision of the flight time module is improved. The number of the pulse signals collected in each collection time period can reflect the time length of each minimum distance measurement time precision, so that the minimum distance measurement time precision can be calibrated by acquiring the accumulated deviation value of the actual number of pulses and the theoretical number of pulses, the problem of time precision reduction caused by electrical nonlinearity can be effectively corrected without introducing complex test instrument equipment in the calibration process, and the method has an important effect on the practical application of a flight time module and related systems thereof.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a diagram illustrating an exemplary implementation of a time-based precision calibration method;
FIG. 2 is a flow diagram of a method for time accuracy calibration in one embodiment;
FIG. 3 is a flowchart detailing step 202 in one embodiment;
FIG. 4 is a diagram illustrating distribution of pulse signal acquisition under different conditions in an embodiment;
FIG. 5 is a flowchart detailing step 202 in one embodiment;
FIG. 6 is a schematic diagram illustrating a structure corresponding to step 2023 according to an embodiment;
FIG. 7 is a flowchart detailing step 204 in one embodiment;
FIG. 8 is a flowchart detailing step 208 in one embodiment;
fig. 9 is a block diagram showing a configuration of a time accuracy calibration apparatus according to an embodiment.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to provide a thorough understanding of the present application, and in the accompanying drawings, preferred embodiments of the present application are set forth. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the specific embodiments disclosed below.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. In the description of the present application, "a number" means at least one, such as one, two, etc., unless specifically limited otherwise.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Fig. 1 is a schematic diagram of an application environment of the time precision calibration method in an embodiment. As shown in fig. 1, the application environment includes a time-of-flight module 110 and an object 120 to be measured. The time of flight module 110 includes a photodetector 112 and a time to digital converter 114.
In one embodiment, the time of flight module 110 further comprises a transmitter 116. The emitter 116 emits a light beam train toward the object 120 to be measured (the arrow in fig. 1 represents the light beam train), and the photodetector 112 detects the light signal reflected from the object 120 to be measured and converts the light signal into an electrical signal. And simultaneously, the time-to-digital converter 114 at the signal acquisition end acquires the pulse time of the transmitted signal of the transmitter 116 and the pulse time of the reflected signal received by the photoelectric detector 112 and records the pulse times on the same time axis, and the actual distance of the object 120 to be measured is calculated by the time difference of flight of the two pulse times. It should be noted that in other embodiments, the time-of-flight module 110 may also be used with an external transmitter.
The time-of-flight module 110 may be applied to an electronic device, and the electronic device may be any electronic device having a time measurement function, such as a depth camera, a virtual reality device, a 3D scene reconstruction device, and a mobile phone.
The time accuracy calibration method in the present embodiment is described based on the above-described electronic device.
In the time-of-flight module, sampling and calculation of the time dimension is performed by using a time-to-digital converter, and the time accuracy of the time-to-digital converter directly affects the measurement accuracy of the time-of-flight module. Each time-to-digital converter is internally set with a theoretical minimum ranging time accuracy. Due to the nonlinearity of the electronic device, each time-to-digital converter has a slight difference between the actual minimum ranging time precision and the theoretical minimum ranging time precision in each sampling process. In a sampling time period, a plurality of acquisition time periods corresponding to the actual minimum ranging time precision are sequentially subjected to accumulative sampling, so that the deviation between the actual minimum ranging time precision and the theoretical minimum ranging time precision is accumulated, and finally, the deviation is generated between the flight time difference acquired by the time-to-digital converter and the real time difference. In order to obtain an accurate time-of-flight difference acquired by the time-to-digital converter, the minimum ranging time accuracy of the time-to-digital converter needs to be calibrated. However, the actual minimum ranging time accuracy is generally about tens of picoseconds (picosecond), and accurate measurement cannot be performed, so the present application uses the statistical principle of optical detection for calibration.
FIG. 2 is a flow diagram of a method for time accuracy calibration in one embodiment. The time accuracy calibration method is based on a time-of-flight module comprising a photodetector and a time-to-digital converter that collects the pulse signals detected by the photodetector. In one embodiment, a method for time accuracy calibration includes steps 202-210.
Each sampling time period is divided into a plurality of acquisition time periods, and each acquisition time period corresponds to the actual time length of sampling the minimum ranging time precision of the time-to-digital converter each time. The actual length of time each time the time-to-digital converter samples the minimum ranging time accuracy may be the same or different, and thus the length of time of multiple acquisition periods of the same time-to-digital converter may be the same or different.
The types of the photodetectors can be various, and the different types correspond to different preset conditions. The photoelectric detector is used for sending pulse signals with uniform photon number distribution to each acquisition time segment of the time-to-digital converter when the minimum ranging accuracy of the time-to-digital converter is calibrated, and the pulse signals are uniformly distributed in the sampling period time of the time-to-digital converter; also, the photodetector may be used as part of a time-of-flight module for determining the distance to an object in the field of view after a minimum ranging time accuracy calibration. Thus, by calibrating the photodetector and the time-to-digital converter in the calibration mode, the time measurement accuracy can be improved; and after calibration, the time-of-flight measurement can be directly carried out through the photoelectric detector and the time-to-digital converter to obtain higher time measurement accuracy. The problem that time accuracy is reduced due to electrical nonlinearity can be effectively corrected without introducing complex test instrument equipment in the calibration process and the measurement process, and the method plays an important role in the practical application of the time-of-flight module and related systems thereof.
Wherein the preset condition is set for controlling the time-to-digital converter to receive the pulse signal in a sampling time period to be uniformly distributed, thereby the probability that the time-to-digital converter collects the pulse signals in each collection time period is completely consistent and accords with the statistic randomness, the number of the pulse signals collected in each collection time period is completely determined by the time length corresponding to the collection time period, therefore, the number of the pulse signals acquired in each acquisition time period can reflect the time length of each minimum ranging time precision, and therefore, in the subsequent steps, the acquisition of the accumulated deviation values of the actual number of pulses and the theoretical number of pulses is actually equivalent to the acquisition of the accumulated deviation values of the actual minimum ranging time precision and the theoretical minimum ranging time precision, and the problem that complex equipment needs to be introduced to directly measure the actual minimum ranging time precision in the picosecond level is further solved.
In one embodiment, the photodetector is a single photon detector, and dark noise generated inside the photodetector is subject to statistical randomness. Referring to fig. 3, step 202 includes step 2021 and step 2022.
Step 2021, under darkroom conditions, using dark noise of the single photon detector as a pulse signal source.
A Single Photon Detector (SPD) is used as a photodetector, such as a Single Photon Avalanche Diode (SPAD), and generates Dark noise (Dark Count) therein, which is independent of the input optical signal, and the noise is subject to statistical randomness. When the flight time module is completely placed in a darkroom, no photon enters the single-photon detector, and the pulse signal which can be acquired by the time-to-digital converter is completely generated by the dark noise of the single-photon detector. The darkroom condition is not limited, so long as it can be ensured that no photon enters the single-photon detector, for example, the time-of-flight module can be directly and completely wrapped in the light absorption black cloth, so that the time-of-flight module is completely in a dark environment.
The first target time is that when the time-of-flight module operates to the time, the pulse signals caused by the dark noise are uniformly distributed in the whole acquisition time period, and the pulse signals with uniformly distributed photon numbers can be sent to each acquisition time period of the time-to-digital converter, that is, the probability that the pulse signals occur in any acquisition time period is the same. Specifically, referring to fig. 4, in the figure, No.1 is a pulse condition acquired in an acquisition time period corresponding to each minimum ranging time accuracy, and No.2 is a pulse signal acquired by the time-to-digital converter and caused by dark noise, when the acquisition is performed to the first target time, the pulse signals in the No.3 column are uniformly distributed in the whole acquisition time period, and at this time, the number of signals distributed in each acquisition time period (the number of pulses acquired with the actual minimum ranging time accuracy) is related to the time length of the acquisition time period (the time length corresponding to the actual minimum ranging time accuracy), so that counting the number of the pulse signals acquired in each acquisition time period can reflect the time length of each acquisition time period.
The first target time can be set according to the dark count rate of the dark noise, the number of segments of the acquisition time period of the time-to-digital converter and the minimum number of pulses acquired in the acquisition time period. For example according to a formula
Obtaining a first target time T1Wherein M is0For the minimum number of pulses acquired in each acquisition time period (i.e. the number of targets in the subsequent step), m is the actual number of acquisition time periods, tcycleFor one sampling cycle time, the DCR is the dark count rate of dark noise.
In one embodiment, the photodetector is a linear detector; referring to fig. 5, step 202 includes step 2023 and step 2024.
A linear detector, such as an Avalanche Photodiode (APD), needs to detect the accumulation of light energy, and therefore, when the photodetector is a linear detector, a detection light source needs to be provided to enable the linear detector to obtain a pulse signal after receiving the detection light source. In step 2023, a dc light source is provided to illuminate the illuminated plane, and an illumination angle of view of the dc light source on the illuminated plane is ensured to be larger than a receiving angle of view of the time-of-flight module (see fig. 6, where 601 is the dc light source, 602 is the illuminated plane, and 603 is the time-of-flight module). Therefore, light irradiated to the irradiated plane by the direct current light source can be uniformly emitted to all angles, all the photoelectric detectors in the receiving field angle of the time-of-flight module can uniformly receive the direct current light source emitted from the irradiated plane, and therefore pulse signals with uniform photon number distribution are generated, the probability that the pulse signals are acquired by the time-to-digital converter in each acquisition time period is completely consistent, and statistical randomness is met. The illuminated plane may be a lambertian plane, so that the dc light source can be uniformly reflected in all directions when illuminated on the lambertian plane.
The second target time is that when the flight time module operates to the time, the photon quantity distribution of the pulse signal caused by the reflected light received by the linear detector is uniform, and the pulse signal with the uniform photon quantity distribution can be sent to each acquisition time period of the time-to-digital converter, namely the probability that the pulse signal occurs in any acquisition time period is the same. The second target time may be set according to the count rate of the linear detector, the number of segments of the acquisition time period of the time-to-digital converter, and the minimum number of pulses acquired in each acquisition time period, and may specifically refer to the acquisition formula of the first target time.
Each time-to-digital converter comprises a plurality of acquisition time periods in each acquisition cycle, and when pulse signals of a target number are acquired in each acquisition time period, the pulse signals can be considered to be acquired in each acquisition time period, so that the zero acquisition condition of a certain acquisition time period is prevented, and the accuracy of each minimum ranging time can be ensured to obtain a deviation value in the subsequent steps so as to obtain calibration. The target number is usually set to be greater than one, and in order to improve the accuracy of calibration, the target number may be set to three.
In one embodiment, referring to FIG. 7, step 204 includes step 2041 and step 2042.
In one embodiment, each time-to-digital converter comprises a plurality of counting units, the time length of each counting unit corresponding to the time length of each acquisition time period. Step 2041 and step 2042 may be performed by a counting unit. Specifically, each counting unit counts the number of actual pulses acquired by each acquisition segment for the number of high levels of the pulse signals acquired by each acquisition time period, that is, when the pulse signals acquired by each acquisition time period are high levels, the corresponding counting unit counts for one time. In practical applications, the counting unit may be implemented by an adder, or may be implemented by a counter, and is specifically set according to actual requirements, which is not limited herein.
In one embodiment, referring to fig. 7, before step 2041, step 204 further comprises step 2040.
And step 206, acquiring the theoretical number of pulses of the acquisition time period according to the number of the sections of the acquisition time period and the total number of pulses included in the time-to-digital converter.
And obtaining the theoretical number of pulses of the acquisition time period in each sampling period according to the number of the sections of the acquisition time period and the total number of the pulses contained in each time-to-digital converter. Specifically, the number of total pulses in one acquisition cycle time is averaged according to the number of segments (theoretically, the number of pulses acquired in each acquisition time segment is the same), and the theoretical number of pulses in the acquisition time segment can be obtained.
And step 208, acquiring the accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses.
In one embodiment, referring to FIG. 8, step 208 includes step 2081 and step 2082.
And 2081, acquiring a deviation value of each acquisition time period relative to the theoretical pulse number according to the actual pulse number and the theoretical pulse number. In particular, it can be based on a formula
Obtaining deviation values relative to the actual pulse number and the theoretical pulse number, wherein the value of i is taken from 1 to m, and m is collectionNumber of segments of time period, Mcount(i)For the actual number of pulses per acquisition time period,
the theoretical number of pulses for each acquisition time period.
And 2082, accumulating the deviation values of the acquisition time periods to obtain an accumulated deviation value. In particular, according to the formula
And acquiring an accumulated deviation value of the actual pulse number relative to the theoretical pulse number, namely an accumulated deviation value of the actual minimum ranging time precision relative to the ideal minimum ranging time precision.
When the flight time module comprises a time-to-digital converter, the minimum distance measurement time precision in each sampling period of the time-to-digital converter is calibrated according to the accumulated deviation value obtained in the step, so that the problem of the consistency of the minimum distance measurement time precision of multiple sampling of the single time-to-digital converter is solved; when the time-of-flight module includes a plurality of time-to-digital converters, each time-to-digital converter requires non-linear calibration to account for the consistency of the plurality of time-to-digital converters in the time-of-flight module.
Specifically, each time-to-digital converter obtains a corresponding INL calibration file through the above steps, when a set of new sampling period related data of each time-to-digital converter arrives, the whole sampling period and the INL are interpolated to obtain m calibrated minimum ranging time precision values, so that the minimum ranging time precision when each time-to-digital converter performs ranging is kept consistent with the corresponding INL calibration, thereby each time-to-digital converter obtains an accurate time difference, and finally a system related to a time-of-flight module obtains consistency with a real value, for example, a depth image obtained by a direct time-of-flight ranging system keeps ranging consistency inside the system.
According to the time precision calibration method provided by the embodiment, the pulse signals received by the time-to-digital converter within each sampling period are uniformly distributed by controlling the time-to-digital converter, when the pulse signals acquired by the time-to-digital converter within each acquisition time period reach the target number, the actual number of pulses acquired by the time-to-digital converter within each acquisition time period and the total number of pulses acquired by the sampling period are acquired, the theoretical number of pulses within the acquisition time period is further acquired, the accumulated deviation value of the number of pulses is acquired according to the actual number of pulses and the theoretical number of pulses, and finally the minimum ranging time precision is calibrated according to the accumulated deviation value, so that the time measurement precision of the flight time module is improved. The number of the pulse signals collected in each collection time period can reflect the time length of each minimum distance measurement time precision, so that the minimum distance measurement time precision can be calibrated by acquiring the accumulated deviation value of the actual number of pulses and the theoretical number of pulses, the problem of time precision reduction caused by electrical nonlinearity can be effectively corrected without introducing complex test instrument equipment in the calibration process, and the method has an important effect on the practical application of a flight time module and related systems thereof.
It should be understood that although the various steps in the flowcharts of fig. 1-8 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 1-8 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternating with other steps or at least some of the sub-steps or stages of other steps.
In one embodiment, as shown in fig. 9, there is provided a time accuracy calibration apparatus for performing the above time accuracy calibration method steps, based on a time-of-flight module including a photodetector and a time-to-digital converter, the time-to-digital converter collecting pulse signals detected by the photodetector; the time accuracy calibration device includes: a control module 901, a first obtaining module 902, a second obtaining module 903, a third obtaining module 904, and a calibration module 905, wherein:
the control module 901 is configured to control the time-to-digital converter to uniformly distribute the received pulse signals within the sampling time period under a preset condition. Each sampling time period is divided into a plurality of acquisition time periods, and each acquisition time period corresponds to the actual time length of sampling the minimum ranging time precision of the time-to-digital converter each time.
A first obtaining module 902, configured to obtain, when the pulse signals collected by the time-to-digital converter in each collection time period reach a target number, an actual number of pulses collected by the time-to-digital converter in each collection time period and a total number of pulses collected in a sampling cycle time.
A second obtaining module 903, configured to obtain a theoretical number of pulses of the acquisition time period according to the number of segments of the acquisition time period and the total number of pulses included in the time-to-digital converter.
And a third obtaining module 904, configured to obtain an accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses.
A calibration module 905, configured to calibrate the minimum ranging time accuracy in each sampling period of the time-to-digital converter according to the accumulated deviation value.
In one embodiment, the control module 901 includes a first condition setting unit and a first control unit.
And the first condition setting unit is used for taking the dark noise of the single-photon detector as a pulse signal source under the dark room condition.
And the first control unit is used for controlling the single photon detector to run to a first target time so as to enable the pulse signals received by the time-to-digital converter in a sampling time period to be uniformly distributed.
In one embodiment, the control module 901 further includes a second condition setting unit and a second control unit.
And the second condition setting unit is used for providing a direct current light source and an irradiated plane, taking the reflected light irradiated on the irradiated plane by the direct current light source as a detection light source of the linear detector, and setting the irradiation field angle of the direct current light source irradiated on the irradiated plane to be larger than the receiving field angle of the time-of-flight module.
And the second control unit is used for controlling the linear detector to receive the optical signal of the reflected light and operate to a second target time so as to enable the pulse signal received by the time-to-digital converter in a sampling time period to be uniformly distributed.
In one embodiment, the first obtaining module 902 includes a first obtaining unit and a second obtaining unit.
The first acquisition unit is used for taking the number of pulses acquired by each acquisition time period counted currently as the actual number of pulses acquired by each acquisition time period in one sampling period when the pulse signals acquired by the time-to-digital converter in each acquisition time period reach the target number.
And the second acquisition unit is used for acquiring the total number of pulses of one sampling period according to the actual number of pulses acquired in each acquisition time period.
In one embodiment, the first obtaining module 902 further includes a comparing unit.
And the comparison unit is used for counting the number of the pulses acquired in each acquisition time period in real time and comparing the number of the pulses with the target number.
In one embodiment, the third obtaining module 904 includes a third obtaining unit and a fourth obtaining unit.
And the third acquisition unit is used for acquiring deviation values of the acquisition time periods relative to the theoretical pulse number according to the actual pulse number and the theoretical pulse number.
And the fourth acquisition unit is used for accumulating the deviation value of each acquisition time period to acquire an accumulated deviation value.
For the specific definition of the time precision calibration device, reference may be made to the above definition of the time precision calibration method, which is not described herein again. The modules in the device for obtaining time precision calibration can be wholly or partially realized by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
The time precision calibration device provided by the embodiment comprises a control module, a first acquisition module, a second acquisition module, a third acquisition module and a calibration module, the control module controls the pulse signals received by the time-to-digital converter in each sampling period to be uniformly distributed, and when the pulse signals acquired by the first acquisition module in each acquisition time period of the time-to-digital converter reach the target number, acquiring the actual number of pulses acquired by the time-to-digital converter in each acquisition time period and the total number of pulses acquired in the sampling period, and then the second acquisition module acquires the theoretical number of pulses in the acquisition time period, and acquires the accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses through the third acquisition module, and finally the calibration module calibrates the minimum distance measurement time precision according to the accumulated deviation value so as to improve the time measurement precision of the flight time module. The number of the pulse signals collected in each collection time period can reflect the time length of each minimum distance measurement time precision, so that the minimum distance measurement time precision can be calibrated by acquiring the accumulated deviation value of the actual number of pulses and the theoretical number of pulses, the problem of time precision reduction caused by electrical nonlinearity can be effectively corrected without introducing complex test instrument equipment in the calibration process, and the method has an important effect on the practical application of a flight time module and related systems thereof.
In one embodiment, an electronic device is provided, which includes a time-of-flight module, a memory and a processor, the memory storing a computer program therein, the time-of-flight module including a photodetector and a time-to-digital converter and being connected to the processor, the processor implementing the following steps when executing the computer program:
under a preset condition, controlling the pulse signals received by the time-to-digital converter within a sampling time period to be uniformly distributed; each sampling time period is divided into a plurality of acquisition time periods, and each acquisition time period corresponds to the actual time length of sampling the minimum ranging time precision each time by the time-to-digital converter;
when the pulse signals acquired by the time-to-digital converter in each acquisition time period reach a target number, acquiring the actual number of pulses acquired by the time-to-digital converter in each acquisition time period and the total number of pulses acquired by the sampling period;
acquiring the theoretical number of pulses of the acquisition time period according to the number of the sections of the acquisition time period and the total number of pulses contained in the time-to-digital converter;
acquiring an accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses;
calibrating the minimum ranging time accuracy in each sampling period of the time to digital converter according to the accumulated deviation value.
In one embodiment, a computer-readable storage medium is provided, having a computer program stored thereon, which when executed by a processor, performs the steps of:
under a preset condition, controlling the pulse signals received by the time-to-digital converter within a sampling time period to be uniformly distributed; each sampling time period is divided into a plurality of acquisition time periods, and each acquisition time period corresponds to the actual time length of sampling the minimum ranging time precision each time by the time-to-digital converter;
when the pulse signals acquired by the time-to-digital converter in each acquisition time period reach a target number, acquiring the actual number of pulses acquired by the time-to-digital converter in each acquisition time period and the total number of pulses acquired by the sampling period;
acquiring the theoretical number of pulses of the acquisition time period according to the number of the sections of the acquisition time period and the total number of pulses contained in the time-to-digital converter;
acquiring an accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses;
calibrating the minimum ranging time accuracy in each sampling period of the time to digital converter according to the accumulated deviation value.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A time accuracy calibration method, characterized in that it is based on a time-of-flight module comprising a photodetector and a time-to-digital converter that collects the pulse signals detected by the photodetector; the method comprises the following steps:
under a preset condition, controlling the pulse signals received by the time-to-digital converter within a sampling time period to be uniformly distributed; each sampling time period is divided into a plurality of acquisition time periods, and each acquisition time period corresponds to the actual time length of sampling the minimum ranging time precision each time by the time-to-digital converter;
when the pulse signals acquired by the time-to-digital converter in each acquisition time period reach a target number, acquiring the actual number of pulses acquired by the time-to-digital converter in each acquisition time period and the total number of pulses acquired by the sampling time period;
acquiring the theoretical number of pulses of the acquisition time period according to the number of the sections of the acquisition time period and the total number of pulses contained in the time-to-digital converter;
acquiring an accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses;
and calibrating the minimum ranging time precision in each sampling period of the time-to-digital converter according to the accumulated deviation value.
2. The method of claim 1, wherein the photodetector is a single photon detector and wherein the dark noise generated within the photodetector is subject to statistical randomness.
3. The method of claim 2, wherein the step of controlling the time-to-digital converter to uniformly distribute the pulse signal received in the sampling time period under a preset condition comprises:
under the condition of a darkroom, the dark noise of the single-photon detector is used as a pulse signal source;
controlling the single photon detector to operate to a first target time to make the pulse signals received by the time-to-digital converter within a sampling time period evenly distributed.
4. The method of claim 1, wherein the photodetector is a linear detector; under a preset condition, the step of controlling the pulse signal received by the time-to-digital converter in a sampling time period to be uniformly distributed comprises the following steps:
providing a direct current light source and an irradiated plane, wherein reflected light irradiated on the irradiated plane by the direct current light source is used as a detection light source of the linear detector, and the irradiation field angle of the direct current light source irradiated on the irradiated plane is larger than the receiving field angle of the time-of-flight module;
and controlling the linear detector to receive the optical signal of the reflected light and operate to a second target time so as to enable the pulse signal received by the time-to-digital converter in a sampling time period to be uniformly distributed.
5. The method of claim 4, wherein the illuminated plane is a Lambertian plane.
6. The method of claim 1, wherein the step of obtaining the actual number of pulses acquired by said time to digital converter during each said acquisition time period and the total number of pulses acquired by said sampling time period when the number of pulse signals acquired by said time to digital converter during each said acquisition time period reaches a target number comprises:
when the pulse signals acquired by the time-to-digital converter in each acquisition time period reach a target number, taking the number of pulses acquired by each acquisition time period counted currently as the actual number of pulses acquired by each acquisition time period in one sampling time period;
and acquiring the total number of pulses of one sampling time period according to the actual number of pulses acquired in each acquisition time period.
7. The method of claim 1, wherein the step of obtaining a cumulative deviation value for the number of pulses based on the actual number of pulses and the theoretical number of pulses comprises:
acquiring a deviation value of each acquisition time period relative to the theoretical pulse number according to the actual pulse number and the theoretical pulse number;
and accumulating the deviation value of each acquisition time period to obtain the accumulated deviation value.
8. A time accuracy calibration device is characterized in that based on a time-of-flight module, the time-of-flight module comprises a photoelectric detector and a time-to-digital converter, and the time-to-digital converter collects pulse signals detected by the photoelectric detector; the device comprises:
the control module is used for controlling the pulse signals received by the time-to-digital converter in a sampling time period to be uniformly distributed under a preset condition; each sampling time period is divided into a plurality of acquisition time periods, and each acquisition time period corresponds to the actual time length of sampling the minimum ranging time precision each time by the time-to-digital converter;
a first obtaining module, configured to obtain an actual number of pulses collected by the time-to-digital converter in each collection time period and a total number of pulses collected by the sampling time period when pulse signals collected by the time-to-digital converter in each collection time period reach a target number;
the second acquisition module is used for acquiring the theoretical number of pulses of the acquisition time period according to the number of the sections of the acquisition time period and the total number of pulses contained in the time-to-digital converter;
the third acquisition module is used for acquiring the accumulated deviation value of the number of pulses according to the actual number of pulses and the theoretical number of pulses;
and the calibration module is used for calibrating the minimum ranging time precision in each sampling period of the time-to-digital converter according to the accumulated deviation value.
9. An electronic device comprising a time-of-flight module, a memory and a processor, the memory storing a computer program, the time-of-flight module comprising a photodetector and a time-to-digital converter and being coupled to the processor, the processor when executing the computer program implementing the steps of the method according to any one of claims 1 to 7.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 7.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010456077.5A CN111580074B (en) | 2020-05-26 | 2020-05-26 | Time precision calibration method and device and electronic equipment |
| PCT/CN2021/092950 WO2021238641A1 (en) | 2020-05-26 | 2021-05-11 | Time precision calibration method and apparatus, and electronic device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010456077.5A CN111580074B (en) | 2020-05-26 | 2020-05-26 | Time precision calibration method and device and electronic equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111580074A CN111580074A (en) | 2020-08-25 |
| CN111580074B true CN111580074B (en) | 2021-08-20 |
Family
ID=72111014
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010456077.5A Active CN111580074B (en) | 2020-05-26 | 2020-05-26 | Time precision calibration method and device and electronic equipment |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN111580074B (en) |
| WO (1) | WO2021238641A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111580074B (en) * | 2020-05-26 | 2021-08-20 | 深圳市灵明光子科技有限公司 | Time precision calibration method and device and electronic equipment |
| CN112987023A (en) * | 2021-05-11 | 2021-06-18 | 深圳阜时科技有限公司 | Optical sensing device, measuring method thereof and electronic device |
| CN113358169B (en) * | 2021-05-31 | 2022-02-01 | 成都朗锐芯科技发展有限公司 | Automatic calibration compensation method and device for Hall flow sensor |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AUPR301401A0 (en) * | 2001-02-09 | 2001-03-08 | Commonwealth Scientific And Industrial Research Organisation | Lidar system and method |
| US7409416B2 (en) * | 2006-05-30 | 2008-08-05 | Motorola, Inc. | Digital-to-time converter using cycle selection windowing |
| CN106681126B (en) * | 2016-12-09 | 2019-04-30 | 深圳市锐能微科技股份有限公司 | A kind of time-to-digit converter and its apparatus and method that calibrate for error |
| WO2018211801A1 (en) * | 2017-05-19 | 2018-11-22 | シャープ株式会社 | Optical sensor and electronic device |
| WO2019041269A1 (en) * | 2017-08-31 | 2019-03-07 | SZ DJI Technology Co., Ltd. | Delay time calibration of optical distance measurement devices, and associated systems and methods |
| US10585176B2 (en) * | 2017-09-19 | 2020-03-10 | Rockwell Automation Technologies, Inc. | Pulsed-based time of flight methods and system |
| KR20200127189A (en) * | 2018-02-06 | 2020-11-10 | (주) 더몰론코리아 | Non-stick ceramic coating with diamond and colored mica |
| CN108919238B (en) * | 2018-07-18 | 2023-10-27 | 浙江大学 | Inertial measurement unit-based rotary laser radar data correction method and system |
| CN109001713B (en) * | 2018-10-16 | 2020-09-22 | 森思泰克河北科技有限公司 | Ranging precision calibration system |
| CN111580074B (en) * | 2020-05-26 | 2021-08-20 | 深圳市灵明光子科技有限公司 | Time precision calibration method and device and electronic equipment |
-
2020
- 2020-05-26 CN CN202010456077.5A patent/CN111580074B/en active Active
-
2021
- 2021-05-11 WO PCT/CN2021/092950 patent/WO2021238641A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| CN111580074A (en) | 2020-08-25 |
| WO2021238641A1 (en) | 2021-12-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111580074B (en) | Time precision calibration method and device and electronic equipment | |
| US10416293B2 (en) | Histogram readout method and circuit for determining the time of flight of a photon | |
| CA2853109C (en) | Method for measuring radiation by means of an electronic terminal having a digital camera | |
| JP6665873B2 (en) | Photo detector | |
| CN106815867B (en) | TOF camera calibration and correction system, and equipment and method thereof | |
| US20120162632A1 (en) | Real-Time Processing Method and System | |
| US20160356646A1 (en) | Methods for collection, dark correction, and reporting of spectra from array detector spectrometers | |
| JP6304567B2 (en) | Ranging device and ranging method | |
| CN107967701B (en) | Calibration method, device and equipment of depth camera equipment | |
| CN106656390A (en) | Apparatus and method for measuring photon time information | |
| CN112114324A (en) | Distance measuring method and device, terminal equipment and storage medium | |
| CN109254291B (en) | Doppler power spectrum data fusion method and device of cloud radar | |
| CN102486402A (en) | Method and system for measuring pulse laser energy | |
| CN113484870A (en) | Ranging method and apparatus, terminal, and non-volatile computer-readable storage medium | |
| WO2018181013A1 (en) | Light detector | |
| KR102198941B1 (en) | Apparatus and Method for measuring distance using SPAD(Single Photon Avalanche Diode) using TOF(Time of Flight) | |
| Bellisai et al. | Indirect time-of-flight 3D ranging based on SPADs | |
| CN116338708A (en) | Method, device and system for measuring flight time | |
| CN112198494B (en) | Method, device, system and terminal equipment for calibrating flight time module | |
| JP2006029986A (en) | Radiation measuring device | |
| CN113252001A (en) | Bridge settlement measuring method and device, electronic equipment and storage medium | |
| JP4199589B2 (en) | Distance measuring device | |
| RU2684631C1 (en) | Digital reactimeter | |
| CN112415568B (en) | Energy correction method, apparatus, device, system, and computer-readable storage medium | |
| CN115840232B (en) | Drift error correction method for satellite laser ranging |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |