CN116660867A - Distance measuring device and distance measuring method based on light beam scanning - Google Patents

Abstract

The invention provides a distance measuring device based on light beam scanning, which comprises: a beam emitter, a beam deflector, a detector and a controller; the beam deflector deflects the laser beam so as to enable the laser beam to scan the target scene back and forth; the detector receives a sequence of intensities of echo signals reflected by the target scene when the target scene is scanned in a first direction, and receives a sequence of intensities of echo signals reflected by the target scene when the target scene is scanned in a second direction, wherein,andin the process of scanning in two directions respectively, the targetThe moment when the echo signal of the j-th scanning point in the scene is received by the detector; the controller is according toAndand determining the flight time, and calculating the distance information from each point in the target scene to the distance measuring device based on the flight time corresponding to each scanning point in the target scene.

Description

Distance measuring device and distance measuring method based on light beam scanning

Technical Field

The invention relates to the technical field of laser ranging, in particular to a ranging device and method based on beam scanning.

Background

The light beam (usually laser) scanning range radar (laser radar for short) can be used for detecting the position, the outline and the speed of a target, the application field of the laser radar is gradually expanded, accurate measurement, navigation positioning and safe obstacle avoidance are performed, and the laser radar starts to be applied to unmanned technology. The laser radar is to scan and emit the emitted light beam to form a scanning section, so as to test the characteristic information of the object to be tested.

Currently, the beam ranging technique used by a typical lidar calculates the distance from the time of flight of light, i.e. the distance between the rangefinder and the object being measured is half the product of the speed of light and the round trip time.

In light-based time-of-flight beam ranging, pulsed beam ranging is currently one of the most widely used. The pulse beam ranging is that a pulse beam with extremely short duration is sent out by a beam emission system, and after the distance L to be measured is passed, the pulse beam is reflected by a target scene, and the reflected echo signal is received by a photoelectric detector in a beam receiving system. The time interval circuit calculates the time t between the emission of the pulse beam and the arrival of the echo signal to obtain the distance L between the target scene and the emission. The pulse beam ranging is simply to measure the flight time difference of the beam, and the pulse beam ranging is performed by utilizing the characteristics of extremely short duration time, relatively concentrated energy in time and high instantaneous power of the pulse beam. The accuracy depends on: rising edge of the pulsed light beam, receive channel bandwidth, detector signal-to-noise ratio, and time interval accuracy.

In addition, the range and the dot frequency of the pulsed beam ranging method are a pair of parameters that are mutually restricted. The flight time of one pulse beam cannot be longer than the time interval between two adjacent pulse beams, otherwise, the pulse beams overlap, and the time interval between the same pulse transmitting time and the same pulse receiving time cannot be accurately judged, so that the reliability of ranging is lost, and therefore, the ranging range is limited to half of the time interval of the pulse beams multiplied by the light speed. The time interval of the pulse beam is exactly the reciprocal of the pulse repetition frequency (abbreviated as the repetition frequency), so the distance measurement range is linearly inversely related to the repetition frequency, the pulse repetition frequency in the prior art is generally 1 kHz-100 kHz, and the distance measurement range is tens of meters to hundreds of meters. The point frequency means that the distance measurement can be performed for several times within 1 second, if the distance measurement is performed according to one pulse, the point frequency is just equal to the repetition frequency, namely 10000 times of distance measurement can be performed within 1 second, namely 10000 points in a scanned target scene are scanned, and the resolution for radar point cloud imaging is low. In order to ensure the ranging range, the repetition frequency cannot be too high, so that the point frequency is difficult to increase, the number of the ranging points in unit time is small, and the ranging speed is low, which is also one of the most important factors of the low resolution of the existing laser radar. Pulse beam ranging is the most widely adopted technology of the existing laser radar, however, the rapid application and development of the laser radar are limited by the point frequency. Therefore, a new ranging mode needs to be explored and invented, and the range is not limited by the frequency of points, so that the laser radar can rapidly perform ranging and can perform high-resolution imaging.

Disclosure of Invention

The invention provides a ranging device and a ranging method based on beam scanning, which are used for solving the problems of low ranging speed and low imaging resolution of a beam radar caused by low frequency of the ranging time point of the beam radar in the prior art.

The invention provides a ranging device based on light beam scanning, comprising:

a beam emitter for emitting a laser beam;

the beam deflector is used for deflecting the laser beam so as to enable the laser beam to scan a target scene back and forth;

a detector for receiving, during scanning of the target scene in the first directionLight intensity sequence of echo signals reflected by target sceneAnd in the process of scanning the target scene in the second direction, receiving the light intensity sequence of the echo signal reflected by the target scene +.>Wherein (1)>And->In the scanning process of the two directions, j=1, 2, …, N and N are the number of scanning points in the target scene at the moment when echo signals of the j-th scanning point in the target scene are received by the detector, and the first direction and the second direction are opposite directions;

a controller for receiving the detection of the detectorAnd->Simultaneous recording->And->According to->And->And determining the flight time of the laser beam irradiated to the jth scanning point and received by the detector, and calculating the distance information from each point in the target scene to the distance measuring device based on the flight time corresponding to each scanning point in the target scene.

Wherein the controller is specifically used for receiving the light intensity sequence detected by the detectorAnd->At the same time, the sequence of deflection angles of the beam deflector at the corresponding moment is recorded +.>And->And based on the same direction scanning, the beam deflector passes +.>And->And (3) taking half of the time difference of the laser beam flight time as the distance information between each point in the target scene and the distance measuring device.

The controller is specifically configured to calculate the distance information according to the following formula:

wherein z is _j For the j-th scanning point to distance information of the distance measuring device,is a beam deflectorAngular velocity of deflection at angle, +.>Is a beam deflector at->The angular velocity of the deflection at the angle, c, is the speed of light.

Wherein, the controller is further configured to, during scanning in the first direction, record the moments that the beam deflector is located at the minimum and maximum deflection angles as follows:and->The controller is further configured to, during scanning in the second direction, determine the moments when the recording beam deflector is at the maximum and minimum deflection angles as follows: />And->The controller is specifically configured to calculate the distance information according to the following formula:

wherein z is _j And c is the light speed, which is the distance information from the jth scanning point to the distance measuring device.

Wherein the beam deflector comprises: MEMS micro-mirrors, oscillating mirrors, rotating prisms or optical phased arrays.

Wherein the laser beam comprises: sinusoidal modulation, square wave modulation, pulse modulation or chirped modulated laser beam.

Wherein the laser beam is a beam output by the beam emitter at a constant power.

Wherein, still include: and a mirror between the beam emitter and the beam deflector for reflecting the laser beam to the beam deflector.

The invention also provides a ranging method adopting the ranging device based on the light beam scanning, which comprises the following steps:

controlling a beam emitter to emit a laser beam;

controlling a beam deflector to deflect the laser beam so as to enable the laser beam to scan a target scene back and forth;

when the target scene is scanned in the first direction, the detector is controlled to receive the light intensity sequence of the echo signals reflected by the target sceneAnd when the target scene is scanned in the second direction, the detector is controlled to receive the light intensity sequence of the echo signal reflected by the target scene>Wherein (1)>And->In the scanning process of the two directions, j=1, 2, …, N and N are the number of scanning points in the target scene at the moment when echo signals of the j-th scanning point in the target scene are received by the detector, and the first direction and the second direction are opposite directions;

receiving the detection of the detectorAnd->Simultaneous recording->And->According to->And->And determining the flight time of the laser beam irradiated to the jth scanning point and received by the detector, and calculating the distance information from each point in the target scene to the distance measuring device based on the flight time corresponding to each scanning point in the target scene.

According to the distance measuring device and method based on beam scanning, the laser beam is emitted through the beam emitter; the beam deflector deflects the laser beam so as to enable the laser beam to scan a target scene back and forth; while scanning the target scene in the first direction, the detector receives the light intensity sequence of the echo signals reflected by the target sceneAnd receiving a light intensity sequence of the echo signal reflected by the target scene when the target scene is scanned in the second direction +.>Wherein (1)>And->In the two-direction scanning process, j=1, 2, …, N and N are the number of reflection points in the target scene at the moment when the echo signal of the j-th point in the target scene is received by the detector, and the first direction and the second direction are opposite directions; the controller receives the +.>And->Simultaneous recording->And->According to->And->And determining the flight time of the laser beam irradiated to the jth scanning point and received by the detector, and calculating the distance information from each point in the target scene to the distance measuring device based on the flight time corresponding to each scanning point in the target scene. The distance measurement can be performed on a plurality of points in the target scene in the process of carrying out one round trip scanning on the laser beam. In the invention, the area covered by the beam line formed by the laser beam scanning can be obtained in one round trip scanning, and the round trip scanning of the beam is fully utilized to respectively obtain the detection of the detection device which scans the same scanning point in two scanning directions>And->Corresponding time->And->And according to the time->And->The time of flight of the laser beam is determined. In the conventional laser radar flight time ranging technology, each ranging point needs the time when the laser pulse is sent out and the time when the echo signal is received, and the flight time is calculated through the two times. The invention does not need information of the moment sent by the laser pulse, does not need to consider the problem of overlapping of two adjacent pulse beams, namely does not consider the limitation of the point frequency, solves the problems of small point frequency, few point number and low speed of ranging in unit time of the traditional pulse beam ranging, has no point frequency limitation, can greatly improve the point frequency, and realizes the ultra-high point number of ranging in unit time, thereby improving the imaging resolution.

Drawings

In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of a ranging device structure based on beam scanning and a light path scanned in a first direction according to the present invention;

FIG. 2 is a schematic view of an optical path of the beam scanning-based ranging device of FIG. 1 scanning in a second direction;

fig. 3 is a schematic diagram of a sampling sequence of a detector in the ranging device based on beam scanning according to the present invention.

Fig. 4 is a schematic diagram of the schematic diagram of fig. 3 divided into two sampling sequences in the +x direction and the-x direction and placed side by side above each other.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1 and 2, a ranging apparatus based on beam scanning according to an embodiment of the present invention includes:

a beam emitter 1 for emitting a laser beam 2.

A beam deflector 3 for deflecting the laser beam 2 so that the laser beam 2 reciprocally scans a target scene, specifically, the beam deflector 3 reciprocally swings to deflect the laser beam 2. The laser beam 2 is first scanned in a first direction, for example: in fig. 1, the beam deflector 3 swings in the +x direction, and the laser beam 2 scans the target scene in a first direction and then scans in a second direction, for example: in fig. 2, the beam deflector 3 oscillates in the-x direction and the laser beam 2 scans the target scene in a second direction. Three scan points in the target scene are shown in fig. 1 and 2, a first scan point 6, a second scan point 7 and a third scan point 8, the first and second directions being opposite directions.

A detector 4 for receiving a light intensity sequence of echo signals reflected by the target scene during scanning the target scene in the first directionAnd in the process of scanning the target scene in the second direction, receiving the light intensity sequence of the echo signal reflected by the target scene +.>Wherein (1)>And->And in the scanning process of the first direction and the second direction, the j=1, 2, …, N and N are the number of marked points in the target scene, wherein the j is the time when the echo signal of the j-th point in the target scene is received by the detector. In this embodiment, the detector 4 may be a barrel detector. Specifically, the probe 4 is divided intoReceive->And->In this case, the trigger controller 5 records the corresponding time +.>And->

A controller 5 for receiving the detection of the detectorAnd->Simultaneous recording->And->And according toAnd->And determining the flight time of the laser beam irradiated to the jth scanning point and received by the detector, and calculating the distance information from each point in the target scene to the distance measuring device based on the flight time corresponding to each scanning point in the target scene.

In this embodiment, the target scene is scanned back and forth by the laser beam 2, and the echo signal intensity is detected in real time by the detector 4, and the area covered by the beam line formed by scanning the laser beam can be known in one back and forth scanning, and the two scanning directions are obtained by fully utilizing the back and forth scanning of the beamUp-scan to the same scan point detector 4 receivesAnd->Corresponding time->And->And according to the time->And->The time of flight of the laser beam is determined. In the conventional laser radar flight time ranging technology, each ranging point needs the time when the laser pulse is sent out and the time when the echo signal is received, and the flight time is calculated through the two times. The invention does not need information of the moment sent by the laser pulse, does not need to consider the problem of overlapping of two adjacent pulse beams, namely does not consider the limitation of the point frequency, solves the problems of small point frequency, few point number and low speed of ranging in unit time of the traditional pulse beam ranging, has no point frequency limitation, can greatly improve the point frequency, and realizes the ultra-high point number of ranging in unit time, thereby improving the imaging resolution.

In this embodiment, the controller 5 is specifically configured to receive the sequence of light intensities detected by the detector 4Andthe sequence of deflection angles recorded in the beam deflector 3 at the corresponding instant>And->And based on the same direction scanning, the beam deflector 3 is passed +>And->And (3) taking half of the time difference of the laser beam flight time as the distance information between each point in the target scene and the distance measuring device. Specifically, the controller 5 is electrically connected to the beam deflector 3 and the detector 4, and receives +_s at the detector 4>And->In this case, the trigger controller 5 records the corresponding time +.>And->And respectively acquire the current deflection angle (i.e., swing angle) of the beam deflector 3 +.>And->The controller 5 is specifically configured to calculate the distance information according to the following formula:

wherein z is _j For the j-th scanning point to distance information of the distance measuring device,for beam deflector 3 inAngular velocity of deflection at angle, +.>For beam deflector 3 at +.>The angular velocity of the deflection at the angle, c, is the speed of light.

Specifically, as shown in fig. 1, a process in which the laser beam 2 is scanned in the first direction (the direction in which the beam deflector 3 swings +x) is described, the beam deflector 3 is in the following stateDeflecting to position I at a deflecting angle +.>The laser beam 2 is along L ₁ Direction of flight for a period of time z _j And/c is incident on the jth point (second scanning point 7 in fig. 1) of the target scene. Reflected light L ₂ Again fly for the same time z _j After/c is captured by detector 4, this time is +.>Δt _j ＝2z _j And/c is the time of flight of the laser beam to be detected, at which point the beam deflector 3 deflects to position II by an angle of +.>Whereas the value detected by detector 4 is +.>

FIG. 2 depicts the scanning of the beam in a second direction (the beam deflector 3 oscillates in the-x direction), i.e. the beam deflector 3 deflects in opposite directions, inDeflecting to position I at a deflecting angle +.>The beam of light is along L ₁ Direction of flight for a period of time z _j And/c, then, the video stream is incident to the j point in the target scene. Reflected light L ₃ Again fly for the same time z _j After/c is captured by detector 4, this time is +.>Δt _j ＝2z _j And/c is the time of flight of the beam exiting to the detected position, at which point the beam deflector 3 deflects to position III by an angle of +.>Whereas the value detected by detector 4 is +.>

From the angle of deflectionI.e. position II in fig. 1, is deflected in the-x direction to a deflection angle +.>I.e. position III in fig. 2, takes a time of 2Δt _j Or from the angle of deflection->Deflection to a deflection angle +.>The time taken is also 2Δtj, i.e. +.> Thus, there is the above formula (1).

Where ω is the angular velocity of the deflection of the beam deflector 3, when the current beam deflector 3 deflects, the deflection is decelerated when deflecting to approach the maximum and minimum deflection angles at both ends, the deflection is accelerated when deflecting from the maximum or minimum deflection angle at both ends, and the deflection can be regarded as uniform velocity deflection in the middle larger deflection angle range, or the angular velocity of the deflection is regarded as equal when passing through the same deflection angle from either direction. Thus, the first and second substrates are bonded together,and->The angular velocity ω therebetween can be calculated by the above formula (2).

In another embodiment of the present invention, the controller 5 may also calculate the distance information according to the following formula (7). As shown in fig. 3, the relationship between the deflection angle and the time of the signal detected by the detector 4 is described, and the two curves share the same time axis, so that the relationship can be conveniently observed. During the first direction scanning, the beam deflector 3 swings in the +x direction, and the initial deflection angle isI.e. the minimum deflection angle, may be 0, at which time is +.>The deflection angle increases until the maximum deflection angle is reached +.>At this time is +.>After which the beam deflector 3 adjusts the direction, starts to oscillate in the-x direction, assuming an adjustment time T _R So the second direction starts scanning time +.>The angle of deviation then becomes smaller until the minimum angle of deviation is reached +.>At this time is +.>Fig. 4 depicts in another form the sampling process of fig. 3: the sampling processes in the +x direction and the-x direction are separated and displayed side by side up and down. Fig. 4 clearly illustrates:and->

From fig. 3, it can be seen that:

from fig. 4, it can be seen that:

thus, using the equation relationship of equation (5), the addition of equation (3) and equation (4) can be obtained:

the controller 5 is further configured to, during the scanning in the first direction, set the recording beam deflector at the minimum and maximum deflection angles at the timings of:and->The controller is further configured to, during scanning in the second direction, determine the moments when the recording beam deflector is at the maximum and minimum deflection angles as follows: />And->The controller 5 may also calculate the distance information according to the following formula (7):

in some embodiments, the beam deflector 3 comprises: MEMS (Micro-Electro-Mechanical System) Micro-mirrors, oscillating mirrors, rotating prisms or optical phased arrays.

Taking MEMS as an example, the MEMS performs high-speed deflection through resonance, and can output feedback signals (mainly the starting time of resonance signals), so that each moment and the deflection angle and the swing direction corresponding to the moment can be calculated; for example, the resonance signal is a sine wave, the wave trough to the wave crest is from leftmost to rightmost in the +x direction, the wave crest to the next wave trough is from rightmost to leftmost in the-x direction, and each point of the sine wave corresponds to a corresponding deflection angle. Wherein the swinging mirror, such as: the laser galvanometer (galvo-scanning-system) deflects to a specified angle in real time according to an externally applied control signal, so that the deflection angle can be known in real time according to the control signal. Compared with the MEMS deflection speed, the MEMS deflection speed is faster, but the accuracy of the real-time deflection angle given by the feedback signal is poorer than that of the laser galvanometer. The deflection speed of the rotating prism is relatively slow, and the change of the deflection angle along with time, namely theta (t), can be calculated by monitoring the starting time of each cycle because the rotation speed is constant. The fastest deflection is an optical phased array, which deflects to a specified angle according to the loaded voltage signal, and theoretically, the real-time deflection angle theta (t) can be accurately known, but the optical phased array is limited by the prior art and technology, the working state of the optical phased array is very unstable, and no usable product exists.

The purpose of lidar is to generate a 3D map of the target scene, which requires two-dimensional scanning to generate transverse 2D images (x and y directions) in addition to longitudinal ranging (z direction). If it is desired to produce a high resolution lateral 2D image, for example, the number of lines in the y-direction is up to 1000 and the frame frequency is up to 30Hz, the time for the x-direction to shift from left to right is less than 1/(30×1000) =33 microseconds, i.e. the scanning frequency for the x-direction round trip is greater than 30×1000/2=15 kHz (two lines are swept at a time). The y-direction only needs to meet 15Hz, which is a relatively slow speed, and if the line number is required to be increased (namely, the resolution is increased), the scanning in the x-direction is correspondingly faster. However, the conventional laser radar needs to calculate each scanning point in real time, under the existing system, after the scanning speed is fast, pulse overlapping phenomenon can be caused, and the problem of deviation in transverse 2D image reconstruction caused by too fast deflection of the scanning angle is solved, and the demand for calculation force is also rapidly increased. Meanwhile, the faster the scanning speed, the shorter the calculation time of each point ranging is required, for example, the resolution of 1000×1000, and the time of each point calculation and data transfer is required to be less than 33ns, which is a very high requirement. Limited by these factors, conventional lidars typically operate at lower resolutions. The invention provides a new method, which has the following greatest differences with the traditional laser radar: in the invention, instead of sequentially calculating the flight time of each point, the change of the light intensity of two back lights with time, which is obtained by scanning in the x direction each time, is recorded, and the traditional laser radar needs the time of receiving the back light signal and the time of emitting laser. In actual operation, two adjacent rows (i.e., the +x direction and the-x direction) of signals can be calculated, a pair of detection signals in the +x direction and the-x direction of the jth point of the target scene can be found, and the distance of the jth point can be calculated according to the formula (1) or the formula (7). The method provides two more visual algorithms, and other suitable algorithms can be adopted according to actual application scenes.

The laser beam 2 includes: the laser beam 2 may be an unmodulated constant power output beam.

The constant power output beam yields a fine 2D image, but relatively poor noise immunity. Sinusoidal modulation is easier than pulse modulation, but the ranging computation is more complex. Square wave modulation may be desirable in some particular scenarios, such as special coding to eliminate mutual interference with the same type of lidar. Pulse modulation is generally used and ranging calculations are the simplest.

In some embodiments, the beam scanning based ranging apparatus further comprises: a mirror (not shown) is located between the beam emitter 1 and the beam deflector 3 for reflecting the laser beam 2 to the beam deflector 3. With the addition of the mirror, a more flexible construction and space is possible for setting the position between the beam emitter 1 and the beam deflector 3.

The following describes a ranging method based on beam scanning provided by the present invention, and the ranging method based on beam scanning described below and the ranging device based on beam scanning described above can be referred to correspondingly.

The invention also provides a ranging method adopting the ranging device based on the light beam scanning, which can be executed by a controller in the device, and comprises the following steps:

step S1: the beam emitter is controlled to emit a laser beam.

Step S2: and controlling a beam deflector to deflect the laser beam so as to enable the laser beam to scan the target scene back and forth.

Step S3: when the target scene is scanned in the first direction, the detector is controlled to receive the light intensity sequence of the echo signals reflected by the target sceneAnd when the target scene is scanned in the second direction, the detector is controlled to receive the light intensity sequence of the echo signal reflected by the target scene>Wherein (1)>And->In the two-direction scanning process, j=1, 2, …, N and N are the number of scanning points in the target scene at the moment when the echo signal of the jth scanning point in the target scene is received by the detector, and the first direction and the second direction are opposite directions.

Step S4: receiving the detection of the detectorAnd->Simultaneous recording->And->According to->And->Determining a time of flight of the laser beam to the jth scan point and received by the detector and based onAnd calculating the distance information from each point in the target scene to the distance measuring device according to the flight time corresponding to each scanning point in the target scene.

In the method, the area covered by the beam line formed by scanning the laser beam can be obtained in one round trip scanning, and the round trip scanning of the laser beam is fully utilized to respectively obtain the signals which are scanned in two scanning directions to the same scanning point detector to receive the signalsAnd->Corresponding time->And->And according to the time->And->The method has the advantages that the flight time of the laser beam is determined, the overlapping problem of two adjacent pulse beams is not needed to be considered, namely, the limitation of the point frequency is not considered, the problems that the traditional pulse beam is small in distance measurement point frequency, few in distance measurement points in unit time and low in distance measurement speed are solved, the point frequency limitation is avoided, the point frequency can be greatly improved, the ultra-high distance measurement points in unit time are realized, and therefore the imaging resolution is improved.

In the method, step S4, the detection of the detector is receivedAnd->Simultaneous recording->And->According to->And->The method comprises the steps of determining the flight time of laser beams irradiated to a j-th scanning point and received by a detector, and calculating the distance information from each point in a target scene to a distance measuring device based on the flight time corresponding to each scanning point in the target scene, wherein the method comprises the following two implementation modes:

mode one:

light intensity sequence detected at receiving detectorAnd->At the same time record +.>And->The sequence of deflection angles of the beam deflector recorded at the corresponding instant>And->And based on the same direction scanning, the beam deflector passes +.>And->And (3) taking half of the time difference of the laser beam flight time as the distance information between each point in the target scene and the distance measuring device.

The distance information is specifically calculated according to the following formula:

wherein z is _j For the j-th scanning point to distance information of the distance measuring device,is a beam deflectorAngular velocity of deflection at angle, +.>Is a beam deflector at->The angular velocity of the deflection at the angle, c, is the speed of light.

Mode two:

in the first direction scanning, the moments of the recording beam deflector at the minimum and maximum deflection angles are respectively:andthe controller is further configured to, during scanning in the second direction, determine the moments when the recording beam deflector is at the maximum and minimum deflection angles as follows: />And->The controller is specifically configured to calculate the distance information according to the following formula:

wherein z is _j And c is the light speed, which is the distance information from the jth scanning point to the distance measuring device.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A range finder based on beam scanning, comprising:

a beam emitter for emitting a laser beam;

the beam deflector is used for deflecting the laser beam so as to enable the laser beam to scan a target scene back and forth;

a detector for receiving a light intensity sequence of echo signals reflected by the target scene during the process of scanning the target scene in the first directionAnd in the process of scanning the target scene in the second direction, receiving the light intensity sequence of the echo signal reflected by the target scene +.>Wherein (1)>And->In the scanning process of the two directions, j=1, 2, …, N and N are the number of scanning points in the target scene at the moment when echo signals of the j-th scanning point in the target scene are received by the detector, and the first direction and the second direction are opposite directions;

a controller for receiving the detection of the detectorAnd->Simultaneous recording->And->According to->And->And determining the flight time of the laser beam irradiated to the jth scanning point and received by the detector, and calculating the distance information from each point in the target scene to the distance measuring device based on the flight time corresponding to each scanning point in the target scene.

2. The beam scanning-based ranging apparatus as recited in claim 1, wherein the controller is configured to receive a sequence of light intensities detected by the detectorAnd->At the same time, the sequence of deflection angles of the beam deflector at the corresponding moment is recorded +.>And->And based on the same direction scanning, the beam deflector passes +.>Andand (3) taking half of the time difference of the laser beam flight time as the distance information between each point in the target scene and the distance measuring device.

3. The beam scanning based distance measuring device according to claim 2, wherein the controller is specifically configured to calculate the distance information according to the following formula:

wherein z is _j For the j-th scanning point to distance information of the distance measuring device,is a beam deflector at->Angular velocity of deflection at angle, +.>Is a beam deflector at->The angular velocity of the deflection at the angle, c, is the speed of light.

4. The beam scanning-based distance measuring device according to claim 1, wherein the controller is further configured to record, during the first direction scan, the moments when the beam deflector is at the minimum and maximum deflection angles, respectively, as:and->The controller is further configured to, during scanning in the second direction, determine the moments when the recording beam deflector is at the maximum and minimum deflection angles as follows: />And->The controller is specifically configured to calculate the distance information according to the following formula:

wherein z is _j And c is the light speed, which is the distance information from the jth scanning point to the distance measuring device.

5. The beam scanning-based distance measuring device according to claim 1, wherein the beam deflector comprises: MEMS micro-mirrors, oscillating mirrors, rotating prisms or optical phased arrays.

6. The beam scanning-based distance measuring device according to claim 1, wherein the laser beam comprises: sinusoidal modulation, square wave modulation, pulse modulation or chirped modulated laser beam.

7. The beam scanning-based distance measuring device according to claim 1, wherein the laser beam is a beam output by the beam emitter at a constant power.

8. The beam scanning-based distance measuring device according to any one of claims 1 to 7, further comprising: and a mirror between the beam emitter and the beam deflector for reflecting the laser beam to the beam deflector.

9. A ranging method using the beam scanning-based ranging apparatus as claimed in any one of claims 1 to 8, comprising:

controlling a beam emitter to emit a laser beam;

controlling a beam deflector to deflect the laser beam so as to enable the laser beam to scan a target scene back and forth;

when the target scene is scanned in the first direction, the detector is controlled to receive the light intensity sequence of the echo signals reflected by the target sceneAnd when the target scene is scanned in the second direction, the detector is controlled to receive the light intensity sequence of the echo signal reflected by the target scene>Wherein (1)>And->In the scanning process of the two directions, j=1, 2, …, N and N are the number of scanning points in the target scene at the moment when echo signals of the j-th scanning point in the target scene are received by the detector, and the first direction and the second direction are opposite directions;

receiving the detection of the detectorAnd->Simultaneous recording->And->According to->And->And determining the flight time of the laser beam irradiated to the jth scanning point and received by the detector, and calculating the distance information from each point in the target scene to the distance measuring device based on the flight time corresponding to each scanning point in the target scene.