CN116794672A - Distance detection system - Google Patents
Distance detection system Download PDFInfo
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- CN116794672A CN116794672A CN202210245455.4A CN202210245455A CN116794672A CN 116794672 A CN116794672 A CN 116794672A CN 202210245455 A CN202210245455 A CN 202210245455A CN 116794672 A CN116794672 A CN 116794672A
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Abstract
The application discloses a distance detection system which is characterized by comprising a light source module for emitting a light source, an internal reflection module for reflecting light in a light path, an auxiliary sensor for receiving the internal reflection light and a receiving module for receiving the reflected light of a detected object. The problem of reduced ranging accuracy caused by the fact that detection pulses emitted by the light source module are actually emitted square waves is solved, and accordingly ranging accuracy is effectively improved.
Description
Technical Field
The application relates to the technical field of distance measurement, in particular to acquisition of a histogram reference point in a distance information acquisition system of a DTOF type.
Background
LiDAR (Light Detection and Ranging, liDAR) is a radar system that detects characteristic quantities such as the position, speed, etc. of a target object by emitting a laser beam. The working principle is that a laser detection signal is emitted to a target object, then the received signal reflected from the target object is compared with the emitted detection signal, and after signal processing is carried out according to the comparison result, the related information of the target object, such as parameters of distance, azimuth, height, speed, gesture, even shape and the like between the laser radar and the target object, is obtained. In addition, the laser radar has high measurement accuracy, fine time and spatial resolution, and can perform functions such as distance measurement (ranging), target detection, imaging, tracking, image recognition and the like, wherein the ranging is a basic function of the laser radar.
Currently, lidars may use the time of flight principle of light to measure the distance between the lidar and the target object, for example, by the formula: r=c×t/(2×n) to calculate the distance between the lidar and the target object. Where n is the refractive index in the medium through which the light propagates and c is the speed of light, which is approximately 299792.458km/s. The principle can realize detection of several meters to several kilometers.
In the ToF measurement method using a pulse wave, the transmitted signal is not a continuous wave but a pulse wave, and the optical signal to be transmitted is a standard square wave signal, and the distance between the transmitter and the target object is calculated by measuring the phase delay of the received square wave signal. However, the measuring method has high requirements on the shape of the square waveform, and in practice, the waveform is mostly imperfect, and distortion or burr phenomenon exists. Therefore, the distance measurement error is also larger, so that a method is needed to solve the problem of the distance measurement error caused by the imperfect square wave signal and improve the distance measurement precision.
Disclosure of Invention
The application aims to overcome the defects in the prior art and provide a distance detection system to solve the problem of reduced distance measurement precision caused by the fact that detection pulses emitted by a light source module are actually emitted square waves, so that the distance measurement precision is effectively improved.
In order to achieve the above purpose, the technical scheme adopted by the embodiment of the application is as follows:
the embodiment of the application provides a distance detection system, which is characterized by comprising a light source module for emitting a light source, an internal reflection module for reflecting light in a light path, an auxiliary sensor for receiving the internal reflection light and a receiving module for receiving the reflected light of a detected object.
Optionally, the internal reflection module is at least one of a Diffuser, a DOE, a collimating lens, and a reference plane.
Optionally, the reflected light received by the auxiliary sensor is an actual emitted square waveform.
Optionally, the auxiliary sensor feeds back the received internally reflected light signal to the receiving module.
Optionally, the ranging system further comprises a processing module, and the processing module obtains the distance of the measured object according to the reflected light received by the receiving module.
Optionally, the internal reflection light signal of the auxiliary sensor is fed back to the processing module, and the processing module calibrates the distance according to the internal reflection light signal.
Optionally, the auxiliary sensor is disposed within the imaging region.
The beneficial effects of the application are as follows:
the embodiment of the application provides a distance detection system, which is characterized by comprising a light source module for emitting a light source, an internal reflection module for reflecting light in a light path, an auxiliary sensor for receiving the internal reflection light and a receiving module for receiving the reflected light of a detected object. The problem of reduced ranging accuracy caused by the fact that detection pulses emitted by the light source module are actually emitted square waves is solved, and accordingly ranging accuracy is effectively improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a ranging principle according to an embodiment of the present application;
FIG. 2 is a schematic diagram of an ideal square wave and an actual emitted square wave according to an embodiment of the present application;
FIG. 3 is a schematic diagram of obtaining an actual emitted square wave according to an embodiment of the present application;
FIG. 4 is a schematic diagram of another embodiment of the present application for obtaining an actual transmit square wave;
FIG. 5 is a schematic diagram of another embodiment of the present application for obtaining an actual transmit square wave;
fig. 6 is a schematic diagram of a ranging system according to an embodiment of the present application;
fig. 7 is a schematic diagram of another ranging system according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
Fig. 1 is a schematic diagram of a ranging principle provided by an embodiment of the present application, where the detection system shown in fig. 1 basically includes: the light source module 110, the processing module 120, and the light receiving module 130, where the light source module 110 includes, but is not limited to, a semiconductor laser, a solid state laser, or other types of lasers, when the semiconductor laser is used as the light source, a Vertical-cavity surface emitting laser VCSEL (Vertical-cavity surface-emitting laser) or an edge-emitting semiconductor laser EEL (edge-emitting laser) is used, and the light source module 110 emits a sine wave or a square wave or a triangular wave, or a pulse wave, or the like, and in the ranging application, most of the lasers having a certain wavelength, for example, infrared lasers (most preferably near infrared lasers with a wavelength of 950nm, etc.), the emitted light is projected into the field of view, the detected object 140 existing in the field of view may reflect the projected lasers to form return light, and the return light enters the detection system to be captured by the light receiving module 130, and the light receiving module 130 may include a photoelectric conversion part, where the four-phase delay receiving scheme in the ITOF ranging can be most commonly used to obtain a four-phase delay signal, and the four-phase delay receiving scheme is used to calculate the four-phase delay signal, and the four-delay signal is 90 ° and the four-phase-delay signal is calculated (the four-phase-delay signal is 90 ° and the four-phase-delay signal is 90) and the four-phase-delay signal is calculated by the four-phase, and the four-phase-delay signal is 90) and the four-phase angle is 90, and the four-phase delay time is the four phase, and the phase delay time and the receiving point, the receiving system is 0, and the receiving phase, and the receiving phase and the receiving system, and the receiving device:
the ratio of the difference of A1 and A3 to the difference of A2 and A4 is equal to the tangent of the phase angle. ArcTan is effectively a bivariate arctangent function, which can be mapped to the appropriate quadrant, defined as 0 ° or 180 ° when a2=a4 and a1> A3 or a3> A1, respectively. Wherein A1, A2, A3, A4 are the number of charges received with delays of 0 °, 90 °, 180 ° and 270 °, respectively.
The distance to the target is determined by the following formula:
to this end, it is also necessary to determine the frequency of the emitted laser light, where c is the speed of light,is the phase angle (measured in radians) and f is the modulation frequency. The above scheme can realize the effect of detecting the distance of the detected object in the field of view, the scheme is called a four-phase delay scheme to obtain detection results, of course, the receiving module generates different information by photoelectric conversion, in some cases, the information acquisition of the detected object is also realized by using a 0-degree and 180-degree two-phase scheme, and the target information is obtained by three phases of 0 degree, 120 degrees and 240 degrees, even the five-phase delay scheme is also disclosed in the literature, and the application is not particularly limited.
FIG. 2 is a schematic diagram of an ideal square wave and an actual emitted square wave according to an embodiment of the present application; fig. 2 includes an ideal square wave schematic 201 and an actual emitted square wave schematic 202. During the ranging process, it is desirable that the detection pulse emitted by the light source module is an ideal square wave as shown at 201, but the detection pulse emitted by the actual light source module is an actual emitted square wave as shown at 202. Since the detection pulse emitted by the light source module is an actual emission waveform, nonlinear distortion is caused when the distance between the detected objects is obtained by using the method of the embodiment shown in fig. 1, and the ranging accuracy is reduced. If the actually transmitted outgoing waveform can be obtained, the waveform is fed back to the signal processing device, and the signal processing device can calibrate the received return signal according to the actually transmitted outgoing waveform so as to improve the ranging accuracy. The signal processing device may be a stand-alone device or may be integrated into a sensor chip, and the present application is not particularly limited.
FIG. 3 is a schematic diagram of obtaining an actual emitted square wave according to an embodiment of the present application; as shown in fig. 3, the light source module 330 emits a detection pulse in which most of the light is emitted toward the object to be measured through a Diffuser 310, but a small portion of the light is reflected inside the emission light path through the reflection of the Diffuser 310. The auxiliary sensor340 is configured to receive light 320 reflected from the Diffuser. The reflected light received by the auxiliary sensor340, i.e., the actual transmitted square waveform, is returned by the auxiliary sensor340 to the signal processing device described above for calibration of the ranging signal. The auxiliary sensor340 in the embodiment shown in fig. 3 needs to be disposed within the imaging area to be able to receive light 320 reflected back by the Diffuser.
FIG. 4 is a schematic diagram of another embodiment of the present application for obtaining an actual transmit square wave; the difference between fig. 4 and fig. 3 is that the transmitting light paths are different and the receiving ends are the same. The light source emitted by the light source module in fig. 4 needs to pass through the collimating lens 420 and the DOE410 and then be directed to the object to be measured, and other parts are the same as those shown in fig. 3, and will not be described here again. The collimating lens 420 is used for collimating the divergent laser light source to achieve the effect of parallel and uniform light spots; the DOE410 (diffraction grating) is used to uniformly emit multiple laser beams after passing through the diffraction grating, so as to increase the measurement accuracy and information quantity and complete the entry of the overall scene. The DOE is mainly applied to a structured light algorithm, and light collimated by the light source module is duplicated according to the requirement of the algorithm by a diffraction method. As shown in fig. 4, the light source module emits a light source, wherein most of the light is emitted to the object to be measured through the collimator lens and the DOE, but a small portion of the light source is reflected inside the emission light path through the reflection of the DOE. The auxiliary sensor is used for receiving the light reflected by the DOE. The reflected light 450 received by the auxiliary sensor 440, i.e., the actual transmitted square waveform, the auxiliary sensor 440 returns the actual transmitted square waveform to the signal processing device described above for calibration of the ranging signal. The auxiliary sensor 440 in the embodiment shown in fig. 4 needs to be disposed within the imaging region to be able to receive the light 450 reflected back by the DOE.
FIG. 5 is a schematic diagram of another embodiment of the present application for obtaining an actual transmit square wave; the light source module 530 in fig. 5 emits light sources, wherein most of the light is emitted toward the object to be measured through the collimator lens 520 and the DOE510, but a small portion of the light source is reflected inside the emission light path through the reflection of the collimator lens 520. The auxiliary sensor is used to receive the light reflected from the collimator lens 520. The reflected light 550 received by the auxiliary sensor 540, i.e., the actual transmitted square waveform, the auxiliary sensor 540 returns the actual transmitted square waveform to the signal processing apparatus described above for calibration of the ranging signal. The auxiliary sensor 540 in the embodiment shown in fig. 5 needs to be arranged in the imaging area to be able to receive the light 550 reflected back from the collimator lens.
In further embodiments a reference plane is also included in the ranging system. The reference surface may be any reference calibrated, typically a glass cover plate. The emitted light is emitted from the light source module and reflected from the reference surface and receives the reflected light of the reference surface on the auxiliary sensor. Another portion of the emitted light is emitted from the light source to the object to be measured and receives light reflected back by the object to be measured at the receiving module. The reflection received by the auxiliary sensor, that is, the actually transmitted square wave waveform, is returned to the signal processing device by the auxiliary sensor, and the ranging signal is calibrated.
Fig. 6 is a schematic diagram of a ranging system according to an embodiment of the present application, which includes a light source module 601, a detected object 602, a receiving module 603, and an auxiliary sensor 604, wherein the receiving module includes a processing module 6031. The light source module transmits detection pulses to the detected object, the detected object reflects detection light emitted by the light source module, and the receiving module receives the reflected light of the detected object. The auxiliary sensor obtains an actual transmitting square waveform according to the embodiment, the actual transmitting square waveform is fed back to the receiving module, the processing module in the receiving module obtains the distance of the detected object according to the reflected light signal, and the processing module calibrates the obtained distance of the detected object according to the actual transmitting square waveform fed back by the auxiliary sensor, so that the ranging accuracy is improved.
Fig. 7 is a schematic diagram of another ranging system according to an embodiment of the present application, which includes a light source module 701, a detected object 702, a receiving module 703, an auxiliary sensor 604, and a processing module 705. The light source module transmits detection pulses to the detected object, the detected object reflects detection light emitted by the light source module, the receiving module receives the reflected light of the detected object, and the reflected light is transmitted to the processing module. The auxiliary sensor obtains the actual emission square waveform according to the embodiment, feeds back the actual emission square waveform to the processing module, obtains the distance of the detected object according to the reflected light signal, and calibrates the obtained distance of the detected object according to the actual emission square waveform fed back by the auxiliary sensor, so as to improve the ranging accuracy.
It should be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (7)
1. A distance detection system, characterized in that the distance detection system comprises a light source module for emitting a light source, an internal reflection module for reflecting light in a light path, an auxiliary sensor for receiving the internal reflection light, and a receiving module for receiving the reflected light of a measured object.
2. The distance detection system of claim 1, wherein the internal reflection module is at least one of a Diffuser, a DOE, a collimator lens, and a reference plane.
3. The distance detection system according to claim 1, wherein the reflected light received by the auxiliary sensor is an actual emitted square waveform.
4. The distance detection system of claim 1 wherein said auxiliary sensor feeds back said received internally reflected light signal to said receiving module.
5. The distance detection system of claim 1, wherein the distance measurement system further comprises a processing module that obtains the distance of the object under test from the reflected light received by the receiving module.
6. The distance detection system according to claim 5, wherein said auxiliary sensor internally reflected light signal is fed back to said processing module, said processing module calibrating said distance based on said internally reflected light signal.
7. The distance detection system of claim 1, wherein the auxiliary sensor is disposed within the imaging region.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210245455.4A CN116794672A (en) | 2022-03-14 | 2022-03-14 | Distance detection system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210245455.4A CN116794672A (en) | 2022-03-14 | 2022-03-14 | Distance detection system |
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| CN116794672A true CN116794672A (en) | 2023-09-22 |
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