CN110456370A - Flight time sensor-based system and its distance measuring method - Google Patents
Flight time sensor-based system and its distance measuring method Download PDFInfo
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- CN110456370A CN110456370A CN201910695653.9A CN201910695653A CN110456370A CN 110456370 A CN110456370 A CN 110456370A CN 201910695653 A CN201910695653 A CN 201910695653A CN 110456370 A CN110456370 A CN 110456370A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/17—Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method
Abstract
A kind of flight time sensor-based system and its distance measuring method, the flight time distance measuring method include: according to the sequence of multiple detection frames, frame by frame delay detection light pulse；The reflected light after the detection light pulse is reflected by object under test is received, the initial depth value of each detection frame is obtained；According to the delay time of the initial depth value of each detection frame and corresponding detection light pulse, the depth value curve of delay time variation of the initial depth value with detection light pulse is obtained；According to the depth value curve, the actual measurement depth value of single output frame corresponding with the multiple detection frame is obtained.Above-mentioned flight time sensor-based system can be improved the accuracy of distance detection.
Description
Technical field
The present invention relates to field of sensing technologies more particularly to a kind of flight time sensor-based systems and its distance measuring method.
Background technique
The pulse signal that time-of-flight method (Time Of Flight, TOF) is issued by measuring instrument from be emitted to receive
Time interval or the round-trip testee of laser once caused by phase difference realize the three-dimensional structure or three to testee
Tie up the measurement of profile.TOF measuring instrument can obtain gray level image and range image simultaneously, be widely used in motion sensing control, behavior
The numerous areas such as analysis, monitoring, automatic Pilot, artificial intelligence, machine vision and automatic 3D modeling.
Flight time (TOF) sensor generally comprises: light source module and illuminant module；The light source module is for emitting spy
The pulse detection light of standing wave section and frequency, the detection light reflect on the surface of testee, and reflected light is by described photosensitive
Module is received；The illuminant module calculates tested according to the time difference or phasometer that emit between light wave and reception light wave
The range information of object.
But in the prior art, especially detection environment it is more complicated in the case where, the testing result of TOF sensor can produce
Raw biggish error.
Summary of the invention
The technical problem to be solved by the invention is to provide a kind of flight time sensor-based system and its distance measuring methods, eliminate
The multipath interference problem of light improves the accuracy of distance detection.
To solve the above-mentioned problems, the present invention provides a kind of distance measuring methods of flight time sensor-based system, comprising: according to
The sequence of multiple detection frames, frame by frame delay detection light pulse；Receive the reflection after the detection light pulse is reflected by object under test
Light obtains the initial depth value of each detection frame；According to the delay of the initial depth value of each detection frame and corresponding detection light pulse
Time obtains the depth value curve of delay time variation of the initial depth value with detection light pulse；According to the depth value curve,
Obtain the actual measurement depth value of single output frame corresponding with the multiple detection frame.
Optionally, postpone the detection light pulse frame by frame at the same time.
Optionally, the flight time sensor-based system includes the pixel array being made of multiple pixel units；For each
Pixel unit obtains the initial depth value of each detection frame respectively；Depth value curve corresponding with each pixel unit is obtained respectively.
Optionally, the starting point institute linearly reduced with delay time with greatest gradient with depth value on the depth value curve
Corresponding initial depth value is as actual measurement depth value.
Optionally, it in the case where having more than one turning point on the depth value curve, is required according to range accuracy,
Select the corresponding initial depth value of suitable turning point as actual measurement depth value, or with first depth on the depth value curve
Any between starting point that angle value is linearly reduced with greatest gradient with delay time with the delay time point declined and depth value
The corresponding initial depth value of point is as actual measurement depth value.
Optionally, initial depth value is fitted with the delay time of corresponding detection light pulse and obtains the depth value
Curve, the method for the fitting include 2D difference, fitting of a polynomial or piecewise function fitting.
Optionally, in multiple detection frames corresponding to single output frame, the maximum delay time of the detection light pulse is big
In the pulsewidth of the detection light pulse.
Optionally, according to the output frame actual measurement depth value and corresponding multiple detection frames initial depth value,
Obtain depth value amendment rule；Rule is corrected with the depth value, the initial depth value of subsequent each detection frame is modified,
The actual measurement depth value of each detection frame is obtained, at this time the corresponding output frame of each detection frame.
Technical solution of the present invention also provides a kind of flight time sensor-based system, comprising: light source module, for issuing detection
Light pulse；Sensing module for receiving the reflected light after the detection light pulse is reflected by object under test, and obtains the reflection
The feature of light；Control module is connect with the light source module, for controlling the light source module according to the suitable of multiple detection frames
Sequence, frame by frame delay detection light pulse；Processing module is connect with the sensing module, for being handled as follows: according to detection light
And reflected light, obtain the initial depth value of each detection frame；According to the initial depth value of each detection frame and corresponding detection light pulse
Delay time, obtain initial depth value with detection light pulse delay time variation depth value curve；And according to described
Depth value curve obtains the actual measurement depth value of single output frame corresponding with the multiple detection frame.
Optionally, the control module postpones the inspection for controlling the light source module frame by frame at the same time
Survey light pulse.
Optionally, the flight time sensor-based system includes the pixel array being made of multiple pixel units；The processing
Module is used to be directed to each pixel unit, obtains the initial depth value of each detection frame respectively, and obtains and each pixel list respectively
The corresponding depth value curve of member.
Optionally, the processing module is used for depth value on the depth value curve with delay time with line of greatest slope
Property reduce starting point corresponding to initial depth value as actual measurement depth value.
Optionally, in the case where having more than one turning point on the depth value curve, the processing module is used for
It is required according to range accuracy, selects the corresponding initial depth value of suitable turning point as actual measurement depth value, or with the depth
The point and depth value that first depth value declines with delay time on angle value curve are linearly reduced with delay time with greatest gradient
Starting point between any point corresponding to initial depth value as actual measurement depth value.
Optionally, the processing module is used to intend initial depth value with the delay time of corresponding detection light pulse
It closes and obtains the depth value curve, the method for the fitting includes 2D difference, fitting of a polynomial or piecewise function fitting.
Optionally, in multiple detection frames corresponding to single output frame, the maximum delay time of the detection light pulse is big
In the pulsewidth of the detection light pulse.
Optionally, the processing module is also used to according to the actual measurement depth value of the output frame and corresponding multiple inspections
The initial depth value of frame is surveyed, depth value amendment rule is obtained；Rule is corrected with the depth value, to the first of subsequent each detection frame
Beginning depth value is modified, and obtains the actual measurement depth value of each detection frame, at this time the corresponding output frame of each detection frame.
Distance measuring method of the invention eliminates influence of the multiple reflections light to testing result by delay detection light pulse, from
And testing result is modified, improve the accuracy of distance detection.
Detailed description of the invention
Fig. 1 is reflection path schematic diagram present in the ranging process of a specific embodiment of the invention；
Fig. 2 a be a specific embodiment of the invention there is only the schematic diagrames of detection light pulse daley when primary event light；
Detection optical pulse delay shows when Fig. 2 b is the primary presence of a specific embodiment of the invention and multiple reflections light
It is intended to；
Fig. 3 is the flow diagram of the ranging process of the embodiment of the invention；
Fig. 4 is the schematic diagram of a corresponding relationship between output frame and detection frame of the embodiment of the invention；
Fig. 5 is that the detecting distance of the embodiment of the invention is illustrated with the curve that detection light pulse moves back number variation
Figure；
Fig. 6 is the schematic diagram of the corresponding relationship between the multiple output frames and detection frame of the embodiment of the invention；
Fig. 7 is the schematic diagram of the embodiment of the invention being modified to distance measurement result；
Fig. 8 is the structural schematic diagram of the flight time sensor-based system of the embodiment of the invention.
Specific embodiment
As described in the background art, the time-of-flight sensor of the prior art, under more complicated detection environment, detection
Error can be larger.
The study found that a part is as caused by multiple reflections light in detection error, multiple reflections light passes through inventor
Multiple reflection path transmission, it is the reason for leading to testing result inaccuracy that light path is larger and is delayed by reception.Be specifically described as
Under:
Fig. 1 (a) is please referred to, only exists primary reflecting light in this case, the detection light that light source module issues directly reaches
Object to be detected surface, the and when reflected light after being reflected by object under test is directly received by illuminant module, according to transmitting light wave and
Receive light wave between time difference or phase difference with apart from corresponding.
And during actual measurement, in the case where measurement environment is complex, there are the multipath interference problems of light.
Part detection light directly reaches testee surface, and reflected light is also directly received by illuminant module；And part detection light may quilt
Reach testee surface after interfering object multiple reflections, and the reflected light of part testee surface reflection may also can be by
Chaff interferent multiple reflections and then it is secondary by illuminant module receive (please referring to Fig. 1 (b)).Such case will lead to part detection light
And/or the light path of reflected light is greater than twice of the distance between actual light source and testee, transmitting light wave and reception light wave it
Between time difference or phase difference and distance between it is not corresponding, cause the range information accuracy finally detected decline.
Further, Fig. 2 a and Fig. 2 b is please referred to, in the specific embodiment, the pulse of the detection light is rectangle arteries and veins
Punching.During received to reflected light, receiving reflected light signal by shutter G2 and G3, (practical includes the reflected light of detection light
And environment light), ambient light signal is received by shutter G1.Specifically, described shutter G1, G2, G3 can pass through capacitance structure
It realizes, environment light and reflected light are converted optical signals to electric signal, passed through shutter by after the pixel unit reception of sensor array
G1, G2 and G3 accumulate the charge of electric signal, and the quantity of electric charge of acquisition is directly proportional to light energy.Described shutter G1, G2 and G3
The time of integration be T, with detection the pulsewidth of light pulse it is consistent, the depth value can be distance, or with apart from right
The intermediate parameters answered, such as the ratio of the quantity of electric charge that shutter G2 and G3 are respectively received, the quantity of electric charge can pass through voltage etc.
Electrical parameter characterization.The edge of the integrated pulse of described G1, G2, G3 is successively aligned, the failing edge of G1 and the rising edge alignment of G2,
The failing edge of G2 and the rising edge alignment of G3.
(Fig. 2 a is please referred to) in the case where no multiple reflections, and the accumulative electricity of each shutter is respectively represented with G1, G2 and G3
Lotus amount, then when detection light pulse LO1 is aligned with shutter G2 pulse, i.e., when delay is 0, shutter G2 and G3 are accumulated to part reflection
It is as follows to expose distance corresponding to the depth value measured for light energy:
Since the ambient light energy amount that shutter G1, G2 and G3 are collected is all the same, in the case where not considering environment light, can incite somebody to action
Simplified formula are as follows:
Wherein, G2 ' and G3 ' indicate the reflection luminous energy after detection light that shutter G2 and G3 are received is reflected by object under test
Amount.Detected depth information withOrIt is directly proportional.
Since the luminous intensity of detection light and time control have error, the detection light pulse is difficult to the rectangle of standard
Pulse.Therefore, this in other specific embodiments, the detection light pulse may be triangular pulse or off-gauge
Square wave pulses.At this point, detection distance still withIt is positively correlated.
When detection light pulse is not moved,
Detecting distance d withIt is positively correlated；
When pulse moves back Ts,
Wherein d0WithRelationship it is constant.
For there is no the case where multiple reflections, as long as reflected light is not moved out of the range of receiving of shutter G3, d0Increase
Amount is just equal toTherefore, d will not change；And after reflected light is fully removed the range of receiving of shutter G2,d0It is not further added by, therefore d is with delay time Ts linear reduction.
For there is the case where Multipath reflection, Fig. 2 b is please referred to, since the light path of multiple reflections light is greater than primary reflecting light
Light path, then reaching time of sensor array of sensor will postpone.Detect the corresponding reflected light LB11 of light pulse LO11
Including first reflection light and multiple reflections light, multiple reflections light energy is smaller；Primary event light pulse and detection light pulse it
Between offset Td it is directly proportional to actual range, and multiple reflections light, than primary event optical retardation Tp, this will lead to shutter
G3 has received the multiple reflections light of additional Tp time, obtains more reflected light energies, according to formula (2) it is found that G3 ' is bigger than normal
It is bigger than normal than actual range to will lead to the distance measured.
According to the studies above, inventor it has furthermore been found that moved back by will test light pulsewidth, can make reflected light also after
It moves, secondary and multiple reflections light is more due to postponing, and decay part can gradually be exceeded the reception model of the integrated pulse of shutter G3
It encloses, and can not be received by shutter G3, so that reducing secondary and multiple reflections light delay part and adjusting the distance to detect influences.Please refer to figure
2b, when detecting light pulse LO12 delay time Ts=Td+Tp, secondary reflection light is delayed in the portion of primary reflecting light Tp period
Dividing will be unable to be received by shutter G3 again, and shutter G3 is only capable of receiving the reflected light within T time, at this point, shutter G2 is also by nothing
Method is collected into reflected light energy, so that the initial depth value measured can increase and linear reduction with delay time, that is to say, that no
Pipe, can be with initial depth value d with the corresponding initial depth of starting point of delay time linear reduction either with or without multiple reflections light
Actual range of the angle value as target reverberation, so as to eliminate the influence of multiple reflections light.
But in actual ranging process, we simultaneously can not know specific delay time of multiple reflections light, therefore nothing
Method accurately sets the optimum delay time of detection light pulse.
For this purpose, inventor proposes a kind of new flight time sensor-based system and its distance measuring method, using detection light pulse by
The method of frame delay gradually being moved back by repeatedly will test light pulse, being modified to testing result.
With reference to the accompanying drawing to the specific implementation of a kind of flight time sensor-based system provided by the invention and its distance measuring method
Mode elaborates.
Referring to FIG. 3, the process for the distance measuring method of the flight time sensor-based system of the embodiment of the invention is shown
It is intended to.
The distance measuring method of the flight time sensor-based system includes at least following steps:
Step S101: according to the sequence of multiple detection frames, frame by frame delay detection light pulse.
In the specific embodiment, the detection data of each output frame passes through the detection data to multiple detection frames
It is handled and is obtained, output frame one testing result of corresponding output, and the corresponding progress one-time detection exposure of a detection frame
Light.Referring to FIG. 4, for the first output frame F1, correspond to n detection frame f11~f1n, subsequently through the detection to n detection frame
As a result it is handled, obtains the first output frame F1Corresponding testing result.
In the specific embodiment, with first detection frame f11Detection light pulse generation timing on the basis of, subsequent detection
Frame f12~f1nDetection light pulse postpone frame by frame, gradually by the part of multiple reflections light delay and primary reflecting light beyond fast
Within the scope of the door G3 time of integration.
In a specific embodiment, t postpones the detection light pulse frame by frame at the same time.With the first inspection
The the first detection light pulse delay time for surveying frame is 0, and the second detection light pulsion phase of the second detection frame is to first detection light
Pulse delay t, total delay time are t；The third detection light pulsion phase of third detection frame prolongs for the second detection light pulse
The slow time is also t, and total delay time is 2t, and so on, the detection light pulsion phase of n-th of detection frame examines (n-1)th
The detection optical pulse delay t of frame is surveyed, total delay time is (n-1) t.
In other specific embodiments, the time interval of delay can also be reduced frame by frame, start several detection frames it
Between, snooze interval is larger, and to improve efficiency, such as the second detection pulsed light detects pulse light delay 3t with respect to one first, the
Three detection pulsed lights detect pulse light delay 2t relative to second, and so on.
The detection light pulse can be realized by the lighting timings of the light source module of control flight time sensor-based system
Postpone frame by frame.
Step S102: the reflected light after the detection light pulse is reflected by object under test is received, the first of each detection frame is obtained
Beginning depth value.
The depth value can be distance, or with apart from corresponding other parameters.It is subsequent with the depth value
It is equal to distance to be described.
The initial depth value can be calculated according to formula (1), work as reflected light, and either primary reflecting light is still more
Secondary reflection light by the received situation of shutter G2 and G3, although moving back with detection pulsed light, will lead to shutter G3 reception
To reflected light energy be gradually increased, and the reflected light energy that shutter G2 is received gradually decreases, but calculated initial depth
Angle value is theoretically identical.
And when delay starts gradually to be removed the time of integration region of shutter G3 in the multiple reflections light of primary reflecting light,
The reflected light energy that G3 is received will reduce, and therefore, will lead to and gradually become according to the calculated initial depth value of formula (1)
It is small.
When delay is completely removed the time of integration region of shutter G3 (in such as Fig. 2 b in the multiple reflections light of primary reflecting light
Reflected light LB12), shutter G2 will be unable to receiving reflected light energy at this time, continues to will test optical pulse delay, will lead to
Primary reflecting light is also gradually removed the time of integration region of shutter G3, is caused, the light energy decline for causing shutter G3 to be collected into
Amplitude increases, so that initial depth value fall also increases.
Step S103: it according to the delay time of the initial depth value of each detection frame and corresponding detection light pulse, obtains just
The depth value curve that beginning depth value changes with the delay time of detection light pulse.
Initial depth value is fitted with the delay time of corresponding detection light pulse and obtains the depth value curve, institute
The method for stating fitting includes 2D difference, fitting of a polynomial or piecewise function fitting etc..
Due to only causing reflection light pulse to be moved when detection light pulse moves back there is only primary reflecting light
Out when the time of integration of shutter G3, the energy that G3 is integrated to can decline, and the initial depth value caused is linear with delay time
Decline, therefore, in the case where there was only primary reflecting light, depth value curve will have a turning point.
And for there are in the case where multiple reflections light, such as there are in the case where triple reflection light, triple reflection light, two
Secondary reflection light and primary reflecting light can gradually be removed the time of integration of G3, due to primary reflecting light, secondary reflection light and
The light intensity of triple reflection light is different, causes initial depth value there are three turning points, and the fall off rate after each turning point
Increase.
The starting point that initial depth value is linearly declined with delay time with greatest gradient in order to obtain, in single output frame institute
In corresponding multiple detection frames, the maximum delay time of the detection light pulse is greater than the pulsewidth T of the detection light pulse.
In a specific embodiment, detection range is L0=5m, i.e. detection light pulsewidth T=33ns；Goal theory away from
Light pulse is detected when initial from L=1m to be overlapped with shutter G2, moves back 3.3ns frame by frame later, after moving back 10 times, detects light pulse
It will be overlapped with shutter G3.
Referring to FIG. 5, detecting distance is with the curve for moving back number (i.e. delay time) variation in the specific embodiment
Schematic diagram.
Curve 1 indicate there is only the detecting distance in the case where 1 secondary reflection light with move back number (delay time) variation
Curve synoptic diagram.It is mutually all 1m in the detecting distance and actual range of preceding several detection frames, after moving back to 8 times, reflected light
It is moved out of other than shutter G3, so that detecting distance declines, therefore there are a turning points for curve 1.
And curve 2 indicates the case where there are secondary reflections, it is assumed that secondary reflection light total distance Lp=2m.Due to secondary reflection
Light exists, and the detecting distance of several detection frames of beginning is identical, and is greater than target range.With the delay of pulse detection light, arrive
After postponing the 6th time, secondary reflection light is gradually moved out of G3 receiving time, therefore detecting distance decline disappears when the 8th delay
Except the influence of secondary reflection light, detecting distance is identical as target range, and detection light pulse continues to postpone, and causes detecting distance into one
Step decline, and descending slope is greater than the preceding slope once declined.So there are two turning points, one of turning points for curve 2
Corresponding to actual range.
In actual ranging process, the initial depth information and delay time of multiple detection frames are fitted to form song
Line, the curve may include multiple linear line segments, it is also possible to multiple arc segments or continuous camber line, only when with detection
Optical pulse delay, when so that reflected light being moved out of the receiving time of shutter G2, initial depth value just can be linear with delay time
Decline.Turning point can be the tie point of multiple arc segments, may be exactly the corresponding data point of a certain detection frame, it is also possible to
The data point fitted between two detection frames.
The flight time sensor-based system includes the pixel array being made of multiple pixel units；Each pixel unit is corresponding
Field of detection in measured object apart from variant, and the multiple reflections light that is included in the reflected light that obtains situation not yet
Together, it is therefore desirable to be directed to each pixel unit, obtain the initial depth value of each detection frame respectively and obtain and each pixel respectively
The corresponding depth value curve of unit, so that the testing result obtained to each pixel unit is modified respectively.
Step S104: according to the depth value curve, the reality of single output frame corresponding with the multiple detection frame is obtained
Depth measurement angle value.
Can choose the corresponding initial depth value in turning point position on the depth value curve as individually with multiple inspections
Survey the actual measurement depth value of the corresponding single output frame of frame.
During atual detection, according to the power consumption of ranging efficiency and sensor-based system, computing capability etc., reasonable set prolongs
The delay time of the detection pulsed light of slow number and each detection frame.Enough in detection number of frames, delay time is enough
In the case where length, it will appear all turning points corresponding with the reflected light in each path on the depth value curve, can choose institute
It states initial depth value corresponding to the maximum turning point of two sides slope variation on depth value curve and is used as actual measurement depth value.
It is contemplated that the reasons such as the power consumption of system, detection efficiency, decay time and the precision controlling of delay time are deposited
It is limiting, therefore can also wanted in the case where having more than one turning point on the depth value curve according to range accuracy
It asks, selects initial depth value corresponding to suitable turning point as actual measurement depth value.Alternatively, can be with the depth value curve
The starting point that the point and depth value that upper first depth value declines with delay time are linearly reduced with delay time with greatest gradient
Between any point corresponding to initial depth value as actual measurement depth value.
In other specific embodiments, can with depth value on the depth value curve with delay time with greatest gradient
Initial depth value corresponding to the starting point of linear reduction as actual measurement depth value, the actual measurement depth value obtained at this time closest to
Actual range.
It is moved back by will test light pulse, so that multiple reflections light exceeds the limit of integration of reflected light, it will be able to improve and survey
Away from accuracy.
Referring to FIG. 4, for the first output frame F1, corresponding output actual measurement depth value D1, the first output frame F1Corresponding n
A detection frame, the initial depth value d that the n detection frame is obtained1~d1nIt is handled, obtains first output frame F1Output
Actual measurement depth value D1。
Referring to FIG. 6, for the second output frame F2, corresponding output actual measurement depth value D2, the second output frame F2Corresponding n
A detection frame, the initial depth value d that the n detection frame is obtained1n~d2nIt is handled, obtains second output frame F2Output
Actual measurement depth value D2；And so on, for m-th of output frame Fm, corresponding output actual measurement depth value Dm, m-th of output frame
FmCorresponding n detection frame, the initial depth value d that the n detection frame is obtainedm1~dmnIt is handled, obtains this m-th output
Frame FmThe actual measurement depth value D of outputm。
It, in some embodiments, can be according to the in the case where significant change will not occurring for detection environment
The initial depth value that multiple detection frames of one output frame obtain is handled, and during obtaining actual measurement depth value, it is suitable to obtain
Decay time and delay time etc. be used as subsequent detection parameter.In other specific embodiments, also available
The corresponding delay time Ts of the actual measurement depth value of one output frame can directly will test pulse in the detection process of subsequent frame
Optical pulse delay Ts is detected, can using the testing result of single detection frame as the actual measurement depth value of corresponding output frame, from
And detection efficiency can be improved, reduce system power dissipation.
Referring to FIG. 7, for the distance measuring method schematic diagram in another specific embodiment of the present invention.
After the actual measurement depth value for obtaining the first output frame, the initial depth value and reality of each detection frame of acquisition can be passed through
Mapping function between depth measurement angle value.It is assumed that d1tFor first turnover point value, i.e. depth of the depth value curve of the first output frame
It is worth the corresponding initial depth value of starting point declined with delay time.So available turnover point value d1tEach detection before
The initial depth value d of frame11~d1tMapping function.Theoretically, transfer point value d1tPervious each initial depth value d11~d1tPhase
Together, mapping function is also identical；It, can be with but due to that can have various systematic errors or ambient noise etc. during actually detected
Processing calibration is carried out by multiple mapping function r1~rt, forms final mapping function R, R=(r1, r2 ... rt), it is described
Mapping function R is to correct rule to the depth value that initial depth value is modified.
In subsequent output frame, each output frame only needs a corresponding detection frame, such as with undelayed detection light arteries and veins
Capable detection is rushed in, initial depth value d is obtainedi, by the initial depth value diIt is modified, is obtained real by the mapping function R
Depth measurement angle value Di。
The distance measuring method of above-mentioned flight time sensor-based system detects light pulse by delay, eliminates multiple reflections light to inspection
The influence of result is surveyed, to be modified to testing result, improves the accuracy of distance detection.
A specific embodiment of the invention also provides a kind of flight time sensor-based system.
Referring to FIG. 8, the structural schematic diagram of the flight time sensor-based system for the embodiment of the invention.
The flight time sensor-based system includes: light source module 701, sensing module 702, control module 703 and processing
Module 704.
The light source module 701 is pulse detection light, the light source module for issuing detection light pulse, the detection light
701 for the timing according to setting, successively issues detection light pulse；
Sensing module 702, including multiple pixel units constitute sensor array, for receive the detection light pulse by
Reflected light after surveying object reflection, and obtain the feature of the reflected light.Each pixel unit can receive reflected light, and by light
Signal is converted to electric signal.Each pixel unit is connected to an integrating circuit, is carried out by the electric signal converted to reflected light
Integral obtains the quantity of electric charge corresponding with the flight time of light.The integrating circuit includes three shutter G1~G3, can be led to respectively
It crosses capacitance structure realization and converts optical signals to telecommunications after environment light and reflected light are received by the pixel unit of sensor array
Number, charge accumulation is carried out to electric signal by shutter G1, G2 and G3 respectively, the quantity of electric charge is directly proportional to light energy.
The control module 703 is connect with the light source module 701, for controlling the light source module 701 according to detection
Frame sequential, frame by frame delay detection light pulse.In a specific embodiment, it can control the light source module 701 with identical
Time interval postpone the detection light pulse frame by frame.In other specific embodiments, can also reduce frame by frame delay when
Between be spaced, starting between several detection frames, snooze interval is larger, to improve efficiency.It is more corresponding to single output frame
In a detection frame, the maximum delay time of the detection light pulse is more than or equal to the pulsewidth of the detection light pulse.
Integration sequence of the control module 703 also with the integrating circuit of each pixel unit of the sensor array 702.
The processing module 704 is connect with the sensing module 702, for being handled as follows: according to detection light and instead
Light is penetrated, the initial depth value of each detection frame is obtained；Prolonging for light pulse is detected with corresponding according to the initial depth value of each detection frame
The slow time obtains the depth value curve of delay time variation of the initial depth value with detection light pulse；And according to the depth
It is worth curve, obtains the actual measurement depth value of single output frame corresponding with multiple detection frames.The processing module 704 is used for initial
Depth value is fitted with the delay time of corresponding detection light pulse and obtains the depth value curve, the method packet of the fitting
Include the methods of 2D difference, fitting of a polynomial or piecewise function fitting.
The flight time sensor-based system includes the pixel array being made of multiple pixel units；The processing module 704
For being directed to each pixel unit, the initial depth value of each detection frame is obtained respectively, and obtain and each pixel unit pair respectively
The depth value curve answered.
In some embodiments, in the case where having more than one turning point on the depth value curve, institute
Processing module 704 is stated for requiring according to range accuracy, selects initial depth value corresponding to suitable turning point as actual measurement
Depth value.In another specific embodiment, it can be declined with first depth value on the depth value curve with delay time
Point and the starting point that is linearly reduced with delay time with greatest gradient of depth value between any point corresponding to initial depth
Value is as actual measurement depth value.
In other specific embodiments, the processing module 704 be used for depth value on the depth value curve with
Initial depth value corresponding to the starting point that delay time is linearly reduced using greatest gradient as actual measurement depth value.
In other specific embodiments, the processing module 704 is also used to the actual measurement depth according to the output frame
Value corrects rule with the initial depth value of corresponding multiple detection frames, acquisition depth value；Rule is corrected with the depth value,
The initial depth value of subsequent each detection frame is modified, obtains the actual measurement depth value of each detection frame, at this time each detection
Frame corresponds to an output frame, to improve detection efficiency.
In some embodiments, the processing module 704 can also be according to the multiple of first output frame
Detection frame obtain initial depth value handled, obtain actual measurement depth value during, obtain suitable decay time and
Delay time etc. is used as subsequent detection parameter；Also the corresponding delay time Ts of the actual measurement depth value of available first output frame,
In the detection process of subsequent frame, it the light source module 701 can be directly controlled will test pulse optical pulse delay Ts and be examined
It surveys, using the testing result of single detection frame as the actual measurement depth value of corresponding output frame, so as to improve detection efficiency, reduces
System power dissipation.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
Member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications also should be regarded as
Protection scope of the present invention.
Claims (16)
1. a kind of distance measuring method of flight time sensor-based system characterized by comprising
According to the sequence of multiple detection frames, frame by frame delay detection light pulse；
The reflected light after the detection light pulse is reflected by object under test is received, the initial depth value of each detection frame is obtained；
According to the delay time of the initial depth value of each detection frame and corresponding detection light pulse, initial depth value is obtained with detection
The depth value curve of the delay time variation of light pulse；
According to the depth value curve, the actual measurement depth value of single output frame corresponding with the multiple detection frame is obtained.
2. the distance measuring method of flight time sensor-based system according to claim 1, which is characterized in that between the identical time
Every postponing the detection light pulse frame by frame.
3. the distance measuring method of flight time sensor-based system according to claim 1, which is characterized in that the flight time passes
Sensing system includes the pixel array being made of multiple pixel units；For each pixel unit, the first of each detection frame is obtained respectively
Beginning depth value；Depth value curve corresponding with each pixel unit is obtained respectively.
4. the distance measuring method of flight time sensor-based system according to claim 1, which is characterized in that bent with the depth value
Initial depth value corresponding to the starting point that depth value was linearly reduced using greatest gradient with delay time on line is as actual measurement depth
Value.
5. the distance measuring method of flight time sensor-based system according to claim 1, which is characterized in that bent in the depth value
In the case where there is more than one turning point on line, is required according to range accuracy, select the corresponding initial depth of suitable turning point
Angle value is as actual measurement depth value, or the point and depth that are declined with first depth value on the depth value curve with delay time
Initial depth value corresponding to any point between starting point that value was linearly reduced using greatest gradient with delay time is as actual measurement
Depth value.
6. the distance measuring method of flight time sensor-based system according to claim 1, which is characterized in that initial depth value with
The delay time of corresponding detection light pulse, which is fitted, obtains the depth value curve, and the method for the fitting includes 2D poor
Value, fitting of a polynomial or piecewise function fitting.
7. the distance measuring method of flight time sensor-based system according to claim 1, which is characterized in that single output frame institute is right
In the multiple detection frames answered, the maximum delay time of the detection light pulse is greater than the pulsewidth of the detection light pulse.
8. the distance measuring method of flight time sensor-based system according to claim 1, which is characterized in that according to the output frame
Actual measurement depth value and corresponding multiple detection frames initial depth value, it is regular to obtain depth value amendment；With the depth
Value amendment rule, is modified the initial depth value of subsequent each detection frame, obtains the actual measurement depth value of each detection frame, this
When the corresponding output frame of each detection frame.
9. a kind of flight time sensor-based system characterized by comprising
Light source module, for issuing detection light pulse；
Sensing module for receiving the reflected light after the detection light pulse is reflected by object under test, and obtains the reflected light
Feature；
Control module is connect with the light source module, for controlling the light source module according to the sequence of multiple detection frames, frame by frame
Delay detection light pulse；
Processing module is connect with the sensing module, for being handled as follows: according to detection light and reflected light, obtaining each inspection
Survey the initial depth value of frame；According to the delay time of the initial depth value of each detection frame and corresponding detection light pulse, obtain just
The depth value curve that beginning depth value changes with the delay time of detection light pulse；And according to the depth value curve, obtain with
The actual measurement depth value of the corresponding single output frame of the multiple detection frame.
10. flight time sensor-based system according to claim 9, which is characterized in that the control module is for controlling institute
It states light source module and postpones the detection light pulse frame by frame at the same time.
11. flight time sensor-based system according to claim 9, which is characterized in that the flight time sensor-based system packet
Include the pixel array being made of multiple pixel units；The processing module is used to be directed to each pixel unit, obtains each inspection respectively
The initial depth value of frame is surveyed, and obtains depth value curve corresponding with each pixel unit respectively.
12. flight time sensor-based system according to claim 9, which is characterized in that the processing module is used for described
Initial depth value corresponding to the starting point that depth value was linearly reduced using greatest gradient with delay time on depth value curve as
Survey depth value.
13. flight time sensor-based system according to claim 9, which is characterized in that have on the depth value curve
In the case where more than one turning point, the processing module selects suitable turning point corresponding for being required according to range accuracy
Initial depth value as actual measurement depth value, or declined with delay time with first depth value on the depth value curve
Initial depth value corresponding to any point between starting point that point and depth value are linearly reduced with delay time with greatest gradient
As actual measurement depth value.
14. flight time sensor-based system according to claim 9, which is characterized in that the processing module is used for initial
Depth value is fitted with the delay time of corresponding detection light pulse and obtains the depth value curve, the method packet of the fitting
Include 2D difference, fitting of a polynomial or piecewise function fitting.
15. flight time sensor-based system according to claim 9, which is characterized in that multiple corresponding to single output frame
In detection frame, the maximum delay time of the detection light pulse is greater than the pulsewidth of the detection light pulse.
16. flight time sensor-based system according to claim 9, which is characterized in that the processing module is also used to basis
The initial depth value of the actual measurement depth value and corresponding multiple detection frames of the output frame obtains depth value amendment rule；
Rule is corrected with the depth value, the initial depth value of subsequent each detection frame is modified, the reality of each detection frame is obtained
Depth measurement angle value, each detection frame corresponds to an output frame at this time.
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