CN109212544B - Target distance detection method, device and system - Google Patents
Target distance detection method, device and system Download PDFInfo
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- CN109212544B CN109212544B CN201811054815.2A CN201811054815A CN109212544B CN 109212544 B CN109212544 B CN 109212544B CN 201811054815 A CN201811054815 A CN 201811054815A CN 109212544 B CN109212544 B CN 109212544B
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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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Abstract
The invention discloses a target distance detection method, a device and a system, wherein the method comprises the following steps: receiving a reflected laser beam returned from the detection target; processing the reflected laser beam to obtain a reflected signal; determining one of a plurality of amplitude comparators as an actually used amplitude comparator from the reflected signal; determining a correction threshold by said actually used amplitude comparator; and determining the detection target distance according to the reflection signal and the correction threshold value. By the scheme of the invention, the distance, the speed and the track can be accurately measured, and the type of the target can be identified.
Description
Technical Field
The invention relates to the field of laser detection, in particular to a detection method and a detection system capable of detecting the distance of a target and distinguishing the type of the detected target.
Background
The pulse type three-dimensional laser radar based on the flight time method has the characteristics of long measuring distance, high frequency, low power consumption and the like due to the adoption of the pulse type laser as a light source, and is widely applied to the fields of three-dimensional modeling, environmental perception and the like. The time difference delta T between the laser pulse transmitting time and the diffuse reflection echo pulse receiving time is recorded by the pulse type three-dimensional laser radar of the flight time method, and the round-trip distance between the laser radar and the measured object can be calculated by multiplying the time difference delta T by the light speed C. The three-dimensional shape information of the measured object can be obtained by scanning beams in the pitching direction and the horizontal direction.
An important factor influencing the distance measurement accuracy in the prior art is the measurement accuracy of the time difference Δ T between the laser pulse emission time and the echo reception time. According to a time-of-flight ranging formula:
L＝1/2(C*ΔT)
wherein L is the measured distance and C is the speed of light. As can be calculated from the above equation, a timing error of 1ns will introduce a ranging error of 15 cm. The amplitude of the echo pulse changes greatly after the emitted laser pulse is subjected to diffuse reflection by objects with different reflectivities. For a pulse type laser radar with a laser pulse width of 5-10 nanoseconds, nanosecond time measurement errors, namely distance measurement errors of dozens of centimeters, can be caused when the arrival time of an echo pulse is judged through a constant level, and the application range and the measurement precision of the three-dimensional laser radar are seriously influenced.
Document 1: CN107272011A, discloses the invention relates to a time point identification method, a time point identification system and a laser ranging system, which is characterized in that the echo pulse obtained by detection during measurement is divided into two paths; one path is subjected to peak value holding processing, the peak value holding processing is used for converting the echo pulse into a direct current level, the voltage value of the direct current level is the peak voltage of the echo pulse, and the direct current level is attenuated in a set proportion; the other path is subjected to delay processing, the delay processing is used for carrying out nanosecond-level delay on the echo pulse, and the delay quantity is ensured to be larger than the time delay caused by peak value holding and attenuation; and comparing the voltage values of the attenuated direct current level and the delayed echo pulse, and taking the time when the voltage value comparison result changes as the arrival time of the echo pulse, wherein when the amplitude of the echo pulse changes, the voltage value of the time point identification level also changes, so that the time point identification independent of the echo intensity is realized. The invention is widely applied to pulse laser ranging systems or ranging of two-dimensional or three-dimensional laser radar systems based on different beam scanning modes.
Document 2: CN 107340523A discloses a speed and distance measuring system and a speed and distance measuring method based on laser heterodyne detection with good anti-jamming capability. The speed and distance measuring system comprises a laser, a light path transmitting component, a light path receiving component, a processor, a beam splitter, a beam combiner and a focal plane array detector; the input end of the beam splitter is connected with the output end of the laser; in the two optical signals split by the beam splitter: one path of optical signal is sent to the optical path transmitting component and projected on a target object to be detected, and the other path of optical signal is directly sent to the beam combiner; the optical path receiving component receives the echo signal, and the echo signal is filtered and then converged to the input end of the beam combiner; the beam combiner is used for carrying out coherent mixing on one path of optical signals divided by the beam splitter and the echo signals to obtain difference frequency signals; the focal plane array detector samples, processes and converts the difference frequency signal into analog-digital signal and sends the analog-digital signal into a processor; the processor acquires the speed and distance information of the target object to be detected.
Document 3: CN 205941886U discloses a three-dimensional laser radar ranging system, and the system has set gradually from top to bottom: the laser radar rotating part is used for transmitting laser to a target to be detected and receiving a laser signal reflected by the target; a rotation mechanism for driving the laser radar rotating part; the laser radar fixing part is used for processing the acquired laser signal reflected by the target and driving the rotating mechanism; the laser radar rotating part and the laser radar fixing part are connected through the rotating mechanism. The utility model discloses utilize mechanical rotation scanning mechanism to produce the laser that has certain field angle, realize the ascending one-dimensional scanning of vertical direction, utilize the rotary scanning machine, realize the ascending one-dimensional scanning of horizontal direction to realize the three-dimensional scanning of certain limit, realize the position discernment to target ground thing.
In the prior art, one detection comparator is adopted to detect the target distance, however, as the correction coefficient of the detection comparator is determined for a certain distance in advance, but in actual detection, the requirements of different detection distances on the correction coefficient are different, and at this time, the distance determined by a single detection comparator may have an accumulated error, so that the detection precision cannot meet the actual requirement.
In addition, the existing laser range finders cannot distinguish the types of specific detection targets, and in some application scenarios, different types of targets need to be treated differently.
In order to solve the above technical problem, the present invention provides a target distance detection system, including:
the laser range finder transmitter is used for transmitting a detection laser beam to a detection target;
the laser range finder receiver includes: a plurality of amplitude comparators, a detection comparator and a signal processor;
the laser range finder receiver receives a reflected laser beam returned from a detection target, processes the reflected laser beam to obtain a reflected signal, and sends the reflected signal to the amplitude comparators and the detection comparator;
the amplitude comparators output comparison results to the signal processor to obtain a correction threshold value;
the detection comparator determines a detection target distance based on the reflected signal and a correction threshold.
According to the system of the present invention, it is preferable that one or more amplitude comparators are activated according to the level of the reflected signal.
According to the system of the present invention, it is preferable that the signal processor determines the correction threshold value based on the output signal of the activated amplitude comparator and the amplitude threshold value of the amplitude comparator.
According to the system of the present invention, preferably, different correction coefficients and amplitude threshold values of the plurality of amplitude comparators are predetermined, and the different correction coefficients and the amplitude threshold values correspond to different detection distance ranges;
and inputs different amplitude thresholds to the plurality of amplitude comparators.
The system according to the present invention preferably further comprises: and an infrared detector (IR) for detecting a temperature of the detection target and determining a type of the detection target according to the temperature.
The system according to the present invention preferably further comprises a signal receiving module, an amplifier module, a noise level processing module, and a time-to-voltage conversion module;
the signal receiving module receives the level signal of the reflected laser beam and sends the level signal to the amplifier module for signal amplification processing;
the amplifier module respectively sends the amplified level signals to the detection comparator, the noise level processing module and the plurality of amplitude comparators;
the plurality of amplitude comparators receive different amplitude thresholds and are activated or not activated according to the received level signal, and one or more activated amplitude comparators output comparison signals to the signal processor according to the input level signal and the amplitude thresholds;
the signal processor determines a correction threshold value according to one or more input comparison signals and outputs the correction threshold value to the detection comparator;
the noise level processing module determines and outputs a noise level according to the received level signal;
the detection comparator determines to generate a detection pulse according to an input level signal, a noise level and a correction threshold value and sends the detection pulse to the time-voltage conversion module;
the time-voltage conversion module determines a time difference from the emission of the laser beam to the arrival of the laser beam at the detection target according to the detection pulse.
In order to solve the above technical problem, the present invention provides a method for determining a velocity of an object, which detects a distance difference and a time difference of the object at different positions by one of the above methods, and calculates a motion velocity vector of the object according to the distance difference and the time difference, including: magnitude of velocity and direction of velocity.
According to the method of the present invention, preferably, a speed threshold is preset, and the type of the target is determined according to the relationship between the target movement speed and the speed threshold.
According to the method of the present invention, preferably, the motion trajectory of the target is determined according to the target position, and the motion trajectory of the target is predicted according to the target motion trajectory.
According to the method of the present invention, preferably, the type of the target is determined according to the motion trajectory of the target.
According to the method of the present invention, it is preferable that the type of the object is determined by judging whether the object suddenly changes in speed magnitude and direction. In order to solve the above technical problem, the present invention provides an object detection information sharing system, including one of the above detection devices, wherein object distance information detected by each detection device is shared with each other.
According to the system of the present invention, preferably, the system determines the speed, type or motion track of the target by using one of the methods described above, and the following information is shared by the respective detecting devices: the speed, type or motion trajectory of the object.
In order to solve the technical problem, the invention also discloses a target distance detection method, which comprises the following steps:
step S1, a reflected laser beam returned from the detection target is received.
And step S2, processing the reflected laser beam to obtain a reflected signal.
In step S3, one of the amplitude comparators is determined as an actually used amplitude comparator from the reflected signal.
Activating one or more amplitude comparators according to the level of the reflected signal.
And if the activated amplitude comparator is larger than one, determining to adopt one of the activated amplitude comparators as an actually adopted amplitude comparator according to the level of the reflected signal and amplitude thresholds of different amplitude comparators.
Different correction coefficients and amplitude threshold values of the amplitude comparators are predetermined, and the different correction coefficients and the different amplitude threshold values correspond to different detection distance ranges;
and inputs different amplitude thresholds to the plurality of amplitude comparators.
In step S4, a correction threshold is determined by the actually used amplitude comparator.
And step S5, determining the detection target distance according to the reflection signal and the correction threshold value.
In addition, the temperature of the detection target can be detected, and the type of the detection target can be determined according to the temperature.
The comparator determines the time difference of the laser beam from emitting laser to reaching the detection target according to the reflection signal and the correction threshold value, and determines the distance of the detection target according to the time-of-flight technology.
By adopting the technical scheme of the invention, the following technical effects are achieved: the distance of the target can be accurately detected; the laser radar detection function with the infrared detection function can detect the type of the target; analyzing the track and the speed of the target motion, and evaluating whether the detection target is a human body induction alarm or a false alarm; and (3) target information sharing: the intruder is tracked and its signature and trajectory are communicated to the adjacent sensors.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, and are not to be considered limiting of the invention, in which:
FIG. 1 is a schematic diagram of a prior art object range detection system;
FIG. 2 is a block diagram of a prior art laser rangefinder transmitter;
FIG. 3 is a block diagram of a prior art laser range finder receiver;
FIG. 4 is a block diagram of a laser range finder receiver according to the present invention;
FIG. 5 is a schematic diagram of the structure of the object distance detection system of the present invention;
FIG. 6 is a schematic diagram of the present invention for detecting object velocity and trajectory using an object distance detection system.
Detailed Description
The present invention will now be described in detail with reference to the drawings and specific embodiments, wherein the exemplary embodiments and descriptions are provided only for the purpose of illustrating the present invention and are not to be construed as limiting the present invention.
Referring to fig. 1, a standard lidar detector includes: the device comprises a laser range finder emitter 1, a laser range finder receiver 2, a reflector 3, a motor 4, a communication and control module 5 and a signal processor 6. The laser beam generated by the laser range finder transmitter 1 is rotated 3 by the mirror. The movement of the motor 4 is controlled by a control and communication module 5. The laser rangefinder beam, after contacting any object, is reflected to the mirror 3 and from the mirror 3 to the laser rangefinder receiver 2. The signal is processed by a signal processor 6 which sends information to the user if a real target is detected.
Fig. 2 is a block diagram of the laser range finder transmitter 1. The laser rangefinder transmitter 1 comprises: timer 11, switched mode power supply 12, current driver 13, laser diode 14, power supply 15.
The laser emission timer 11 is triggered by emitting a trigger signal, and the timer 11 sends a laser turn-on signal to the current driver 13. While the timer sends a shutdown pulse signal to the switched mode power supply 12 and the switched mode power supply 12 is powered by the power supply 15, the switched mode power supply 12 is energized by the pulse signal to send a high level to the current driver 13 and at the same time send an APD level to the laser rangefinder transmitter 2. The current driver 13 receives the laser turn-on signal and the high level, and sends a current pulse to the laser diode 14 to send out a laser beam. At the same time, the current driver 13 may send a signal to the laser range finder transmitter 2 to start the measurement.
Fig. 3 is a block diagram of a prior art laser range finder receiver 2. The laser range finder receiver 2 includes: voltage temperature correction module 21, APD22, amplifier 23, noise level module 24, detection comparator module 25, time-to-voltage conversion module 26, voltage 27, buffer 28.
The voltage temperature correction module 21 receives the APD voltage transmitted from the laser range finder transmitter 1, performs voltage temperature correction on the APD voltage, and transmits the APD voltage to the APD 22. APD22 simultaneously receives a laser beam reflected back from a target of detection. APD22 converts the received optical signal to obtain a level signal, and sends the level signal to amplifier 23, and amplifier 23 amplifies the received level signal and sends the amplified level signal to noise level module 24 and detection comparator module 25. The noise level module 24 extracts a noise correction level in the received level signal and transmits it to the detection comparator module 25, while inputting the detection threshold to the detection comparator module 25. The detection threshold of the detection comparator module 25 is slightly above the noise correction level. The comparator generates a detection pulse when the received level signal is above the detection threshold. The probe pulse enters a time-to-voltage or time-to-digital conversion module 26 and is converted to a range value, which is sent to a buffer 28, thereby obtaining a range analog pulse. The power module 27 supplies power to the above modules.
However, for the laser range finder receiver 2 shown in fig. 3, since the correction coefficient of the detection comparator is determined in advance for a certain distance, but the requirements of different detection distances for the correction coefficient are different in actual detection, the distance determined by a single detection comparator may have an accumulated error, so that the detection accuracy cannot meet the actual requirements.
In addition, the existing laser range finders cannot distinguish the types of specific detection targets, and in some application scenarios, different types of targets need to be treated differently.
Fig. 4 shows a laser range finder receiver 2 according to the present invention. As shown, the laser rangefinder receiver 2 is provided with an additional 4 amplitude comparators 29-32 in addition to the prior art functional blocks, with 4 amplitude thresholds, dividing the input signal range into 4 levels. Allowing an estimation of the signal level. The output signals of the 4 amplitude comparators are connected to a signal processor and used to correct the range values. For these 4 levels, there is one correction factor for each level, which is calculated into the detection range. When the laser range finder measures the distance, a correction coefficient is set. The method comprises the following steps:
1. different sized targets are placed at a plurality of measured distances. Smaller targets produce smaller signals than larger targets.
2. The distance of the laser rangefinder is read before the correction value is counted in.
3. Before the correction value is calculated, the distance and the distance to the laser range finder are measured, and the difference is the correction coefficient.
The number of amplitude comparators activated depends on the received signal level. For low level signals, such as those reflected from small or weak reflecting targets, only one amplitude comparator can be activated, while signals reflected from strong or large targets will activate all 4 amplitude comparators.
The resulting correction range is very accurate and can distinguish between two similar targets. For example, a crawling intruder or an object approaching a fence may be detected.
By the solution of the invention provided in fig. 4, distances can be detected more accurately, especially for small, close-distance objects that may be difficult to distinguish, such as a crawling person from the ground, a standing person against a wall, and a wall.
As shown in fig. 3, the conventional laser range finder receiver has only one comparator, and a certain distance range, such as 0-40 m, is set. Whereas the plurality of amplitude comparators 29-32 of the present invention may divide the same distance range into different levels, as in the case of 4 amplitude comparators, each amplitude comparator is responsible for covering a distance of 10 meters. Since each amplitude comparator needs to record a correction coefficient, and errors are accumulated, the detection comparator which is corrected for multiple times within a certain distance range can measure more accurate distance than the detection comparator which is corrected for only once. Assume that the detection ranges of 4 amplitude comparators 29-32 are 0-10 m, 10-20 m, 20-30 m, and 30-40 m, respectively. If an actual distance of an object is 15.2 meters, the actual distance falls within the detection range of the second amplitude comparator 30, i.e., the range of 10-20 meters, without considering other factors, so that the second amplitude comparator 30 can estimate the signal level more accurately.
The calculation mode of the correction coefficient is as follows: if the actual distance is 15.2 meters and the measurement reading is 15.5 meters, the correction value is 0.3 meters difference between the distances, or converted to a percentage.
The activation of the amplitude comparator is determined by the magnitude of the signal level of the object under test. The magnitude of the signal level is determined by the size of the object to be measured, the degree of reflection, the distance, and other factors. Where the distance has the greatest effect on the signal level. If an object is actually 15.2 meters away, its reflection level is large enough to activate all amplitude comparators 29-32. After the amplitude comparators 29-32 output the comparison results level 1-level 4 to the signal processor, the signal processor will determine the result of the second amplitude comparator 30 as the final detection threshold value according to the magnitude of the signal level. I.e. eventually its distance is still detected by the second amplitude comparator 30, while the other three activated comparators do nothing even if activated.
As shown in fig. 5, in the present invention, the laser range finder receiver 2 also incorporates an infrared detector 7. The infrared detector 7 operates independently of the laser range finder receiver 2. During scanning, the mirror 3 reflects the area thermal radiation detected in the field of view of the receiver to the infrared detector 7. The signal processor 6 then calculates a background temperature statistic and creates an infrared detection threshold. When an intruder passes through the scanning area, the temperature measured in a particular field of view changes and an alarm signal is emitted.
Therefore, in conjunction with the description of fig. 4-5, the lidar detector of the present invention has the following functions:
a. the laser radar detection function with the thermal detection/infrared detection function.
b. Target behavior: the trajectory and speed of the object motion are analyzed and whether the detected object is a human body sensing alarm or a false alarm is evaluated.
c. And (3) target information sharing: the intruder is tracked and its signature and trajectory are communicated to the adjacent sensors.
Referring to fig. 6, a target behavior analysis function is described, which is performed by a plurality of lidar detectors. In fig. 6, the working principle of the lidar detector is fast laser scanning, which ensures that the object to be measured is detected by multiple points within the scanning range to trace the movement track and calculate the speed. The velocity is calculated by recording the time of detection and the distance (i.e. TOF time-of-flight technique).
Knowing the trajectory and speed of action, it is possible to predict when and where the object under test will be within the scanning range of the next detector, so that the second detector can lower the detection threshold to better detect the object again. If the trajectory of the object is unnatural, such as with a very sudden change in steering, certain decisions may be made, such as non-human, possibly large birds.
The heat sensing detector 7 continuously works together with the laser radar, and the task of the heat sensing detector 7 is to eliminate the false alarm rate caused by weak detection signals, and at the moment, the detection critical value is set to be very low so as to improve the detection effect. In this case, the heat sensing detector is used to eliminate the false alarm rate. In this way, the detection critical value of the laser radar can be reduced, so that the detection range is expanded.
In order to distinguish objects by detecting their speed and not to calculate objects that move in an unnatural way. It is necessary to set a speed threshold value, and when the speed of the detection target is higher than the set speed threshold value, it can be determined that the detection target is an object not intended to be detected, such as a human being. Therefore, birds and fast-driving vehicles can be shielded, and only human intruders are alarmed. Furthermore, if the target suddenly changes the direction of motion, it may also be judged that the target is a non-human intrusion.
Referring to fig. 6, the group information sharing function of the present invention is described, in which a sensor knows that an intruder is approaching it from a sensor in the vicinity thereof.
This feature is used in the case of several sensors protecting a large area or enclosure. When the target reaches the boundary of the scan area, its size, velocity and position are communicated via the communication protocol to the sensor scan area where an intruder is likely to enter. This improves the detection rate and reduces the false alarm rate.
The target is detected and tracked by a number 1 lidar detector. The intruder's path a is transmitted to lidar detector No. 2. Subsequently, lidar detector No. 2 is expected to detect intruders around point D. Detecting a smaller and less reflective target at point D can be somewhat difficult. Under the condition that an intruder is known to enter a D point in a scanning area of the No. 2 laser radar detector, the No. 2 laser radar detector considers that a target signal is lower than a detection critical value by temporarily reducing the critical value. Lidar detector No. 2 will detect the target and track path B.
The invention also discloses a target distance detection method, which comprises the following steps:
step S1, a reflected laser beam returned from the detection target is received.
And step S2, processing the reflected laser beam to obtain a reflected signal.
In step S3, one of the amplitude comparators is determined as an actually used amplitude comparator from the reflected signal.
Activating one or more amplitude comparators according to the level of the reflected signal.
And if the activated amplitude comparator is larger than one, determining to adopt one of the activated amplitude comparators as an actually adopted amplitude comparator according to the level of the reflected signal and amplitude thresholds of different amplitude comparators.
Different correction coefficients and amplitude threshold values of the amplitude comparators are predetermined, and the different correction coefficients and the different amplitude threshold values correspond to different detection distance ranges;
and inputs different amplitude thresholds to the plurality of amplitude comparators.
In step S4, a correction threshold is determined by the actually used amplitude comparator.
And step S5, determining the detection target distance according to the reflection signal and the correction threshold value.
In addition, the temperature of the detection target can be detected, and the type of the detection target can be determined according to the temperature.
The comparator determines the time difference of the laser beam from emitting laser to reaching the detection target according to the reflection signal and the correction threshold value, and determines the distance of the detection target according to the time-of-flight technology.
Through the scheme of the invention, the following technical effects are achieved:
lidar detection may be provided with thermal/infrared detection functionality.
The distance of the target can be accurately detected; the laser radar detection function with the thermal detection function can detect the type of the target; analyzing the track and the speed of the target motion, and evaluating whether the detection target is a human body induction alarm or a false alarm; and (3) target information sharing: the intruder is tracked and its signature and trajectory are communicated to the adjacent sensors.
The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a transmitter of a general purpose computer, special purpose computer, embedded transmitter, or other programmable data transmission terminal device to produce a machine, such that the instructions, which execute via the transmitter of the computer or other programmable data transmission terminal device, create a system for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data transmission terminal to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction system which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data transmission terminal device to cause a series of operational steps to be performed on the computer or other programmable terminal device to produce a computer implemented transmission such that the instructions which execute on the computer or other programmable terminal device provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.
Finally, it should also be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal 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 terminal. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or terminal that comprises the element.
The above detailed description is provided for the target detection method and system provided by the present invention, and the principle and the implementation of the present invention are explained by applying specific examples, and the description of the above embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (4)
1. An object distance detecting device characterized by comprising:
the laser range finder transmitter is used for transmitting a detection laser beam to a detection target;
the laser range finder receiver includes: a plurality of amplitude comparators, a detection comparator and a signal processor;
the laser range finder receiver receives a reflected laser beam returned from a detection target, processes the reflected laser beam to obtain a reflected signal, and sends the reflected signal to the amplitude comparators and the detection comparator;
activating one or more amplitude comparators according to the level of the reflected signal;
the plurality of amplitude comparators output the comparison results to a signal processor, and the signal processor determines a correction threshold value according to the output signal of the activated amplitude comparator and the amplitude threshold value of the amplitude comparator;
the detection comparator determines a detection target distance according to the reflection signal and a correction threshold value;
the device also comprises a signal receiving module, an amplifier module, a noise level processing module and a time-voltage conversion module;
the signal receiving module receives the level signal of the reflected laser beam and sends the level signal to the amplifier module for signal amplification processing;
the amplifier module respectively sends the amplified level signals to the detection comparator, the noise level processing module and the plurality of amplitude comparators;
the plurality of amplitude comparators receive different amplitude thresholds and are activated or not activated according to the received level signal, and one or more activated amplitude comparators output comparison signals to the signal processor according to the input level signal and the amplitude thresholds;
the signal processor determines a correction threshold value according to one or more input comparison signals and outputs the correction threshold value to the detection comparator;
the noise level processing module determines and outputs a noise level according to the received level signal;
the detection comparator determines to generate a detection pulse according to an input level signal, a noise level and a correction threshold value and sends the detection pulse to the time-voltage conversion module;
the time-voltage conversion module determines a time difference from the emission of the laser beam to the arrival of the laser beam at the detection target according to the detection pulse.
2. The apparatus of claim 1, wherein: different correction coefficients and amplitude threshold values of the amplitude comparators are predetermined, and the different correction coefficients and the different amplitude threshold values correspond to different detection distance ranges;
and inputs different amplitude thresholds to the plurality of amplitude comparators.
3. The apparatus of claim 1, wherein: further comprising: and an infrared detector (IR) for detecting a temperature of the detection target and determining a type of the detection target according to the temperature.
4. An object detection information sharing system comprising a plurality of detection apparatuses according to any one of claims 1 to 3, wherein object distance information detected by the respective detection apparatuses is shared with each other.
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| US11681030B2 (en) * | 2019-03-05 | 2023-06-20 | Waymo Llc | Range calibration of light detectors |
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