CN113093147B - Scanning range finder and method for filtering noise of ranging signal - Google Patents
Scanning range finder and method for filtering noise of ranging signal Download PDFInfo
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- CN113093147B CN113093147B CN202110645277.XA CN202110645277A CN113093147B CN 113093147 B CN113093147 B CN 113093147B CN 202110645277 A CN202110645277 A CN 202110645277A CN 113093147 B CN113093147 B CN 113093147B
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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
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
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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
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
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Abstract
The purpose of this application is to provide a scanning range finder and a method for noise filtering of range signals, the method comprising: a plurality of comparators of the scanning range finder respectively acquire leading edge points of a current range signal to obtain a plurality of leading edge points; selecting a target comparator from a plurality of comparators of a scanning range finder, and acquiring a back edge point of a current ranging signal through the target comparator; determining the leading edge slope of the current ranging signal according to the plurality of leading edge points, and determining the signal width of the current ranging signal according to the trailing edge points and the leading edge points acquired by the target comparator; and searching the corresponding reference signal width in a preset relation reference table according to the leading edge slope of the current ranging signal, and filtering the noise point of the current ranging signal according to the reference signal width and the signal width of the current ranging signal. Therefore, noise generated by spot distortion can be effectively identified and filtered, and the accuracy of environment identification is improved.
Description
Technical Field
The application relates to the technical field of scanning distance measurement, in particular to a scanning distance meter and a method for filtering noise of a distance measurement signal.
Background
The laser scanning range finder is mainly applied to autonomous positioning navigation service of an intelligent robot, is used for unfamiliar environment identification and environment map construction, and is a basic index requirement of the laser scanning range finder for accurately restoring the real appearance in the environment. In a real scene, the situation that the front wall and the rear wall are not connected but are separated independently often exists, and the scene is a test for the laser scanning range finder. In the scanning operation process of the laser scanning range finder, when scanning beams pass through the junction of two walls, part of light spots are projected to the front plate wall body, and the rest of light spots are projected to the rear plate wall body, so that light spot distortion is caused, continuous noise points are further formed between the front plate and the rear plate of a scanning image, and the noise points can be mistaken by a robot as obstacles at the position to influence the result of path planning. In the actual scene, as shown in fig. 1, the laser scanning range finder projects to the situation of two independent boards (walls) in front and back, the front board and the back board exist independently without connection, the area between the front board and the back board is idle, no other obstacles exist, the laser scanning range finder scans along the direction of the two boards, part of light spots project to the front board, the rest of light spots project to the back board, which causes light spot distortion, and the front and back light spots are respectively reflected to the photosensitive element of the laser scanning range finder to form a superposed waveform signal. As shown in fig. 2, a superimposed signal appears, the front plate signal would normally be the signal consisting of a1-B0 and the rear plate signal would normally be the signal consisting of a0-B, with the two signals superimposed to form the a1-B signal due to the simultaneous projection of the light spots onto the front and rear plates. At this time, as shown in fig. 3, a scanning effect of forming continuous noise points between the front board and the rear board due to spot distortion occurs, the near scattering point is the presentation of the front board on the scanning map, the far scattering point is the presentation of the rear board on the scanning map, the middle scattering point is the detection noise point caused by spot distortion, a virtual barrier wall which does not exist is formed in the scanning scene, and the path planning of the robot is influenced.
That is, the robot should work in a partial area between two walls, but a virtual wall is constructed between the front wall and the rear wall due to the false recognition of the laser scanning distance meter of the robot, so that the working area of the robot is limited. More seriously, if the characteristics of independent walls, load-bearing columns and the like exist in an actual scene, the robot can mistakenly think that the periphery of the robot is an obstacle, so that correct path planning or map construction cannot be performed, and effective regional operation cannot be performed.
Disclosure of Invention
An object of the present application is to provide a scanning range finder and a method for filtering noise of a range finding signal, which solve the problem that in the prior art, the laser scanning range finder can not perform path planning or map construction and effective area operation due to the influence of the noise generated by misrecognition on a robot.
According to an aspect of the present application, there is provided a method for noise filtering of a ranging signal, the method comprising:
respectively acquiring leading edge points of a current ranging signal through a plurality of comparators of a scanning range finder to obtain a plurality of leading edge points;
selecting a target comparator from a plurality of comparators of a scanning range finder, and acquiring a back edge point of a current ranging signal through the target comparator;
determining the leading edge slope of the current ranging signal according to the plurality of leading edge points, and determining the signal width of the current ranging signal according to the trailing edge points and the leading edge points acquired by the target comparator;
and searching the corresponding reference signal width in a preset relation reference table according to the leading edge slope of the current ranging signal, and filtering the noise point of the current ranging signal according to the reference signal width and the signal width of the current ranging signal.
Optionally, the method comprises:
and determining a preset relation reference table of the signal leading edge slope and the signal width of the scanned object.
Optionally, the method for determining a preset relationship reference table between a leading edge slope of a signal of the scanned object and a signal width includes:
changing the signal strength of the received signals of the scanned single board, and acquiring the leading edge slope and the signal width of the signals under the signal strength state of each received signal;
and determining a preset relation reference table according to the leading edge slopes and the signal widths of all the collected signals.
Optionally, selecting a target comparator from a plurality of comparators of the scanning range finder comprises:
determining a preset identification threshold corresponding to each comparator of the scanning range finder;
and taking the comparator corresponding to the preset identification threshold value of the minimum value as a target comparator.
Optionally, filtering noise of the current ranging signal according to the reference signal width and the signal width of the current ranging signal includes:
and when the signal width of the current ranging signal is larger than the reference signal width, judging that the current ranging signal is noise.
Optionally, changing the signal strength of the received signal of the scanned single board includes any one of the following manners or a combination of any several manners:
changing the surface reflectivity of the scanned single plate by continuously changing the scanned single plate from white to black;
keeping the surface reflectivity of the scanned single plate unchanged, and changing the continuous change of the driving current of the emitted light of the scanning range finder from strong to weak;
the surface reflectivity of the scanned single plate is unchanged, and the effective luminous flux of the receiving end is changed.
According to yet another aspect of the present application, there is also provided a scanning range finder for noise filtering of range signals, the scanning range finder comprising: the device comprises a photosensitive element, a signal conversion module, a signal amplification module, a comparator module, a time-to-digital converter module and a signal analysis processing module;
the photosensitive element is used for sensing and receiving optical signals on the surface of the measured object and converting the optical signals into electric signals;
the photosensitive element is connected with the signal conversion module, and the signal conversion module is used for converting a current signal excited by the electric signal into a voltage signal;
the signal amplification module is used for amplifying the voltage signal and simulating the generation of signal noise floor;
the comparator module comprises a plurality of identical comparators, and all the comparators are connected to the output end of the signal amplification module together and used for acquiring the information of the leading edge and the trailing edge of the signal output by the signal amplification module;
the time-to-digital converter module comprises a plurality of time-to-digital converters, is respectively connected to the output ends of the comparators and is used for converting the output information of the comparators into flight time information;
the signal analysis processing module is used for collecting the flight time information provided by each time-to-digital converter and determining the ranging result according to the flight time information.
Optionally, the time delay between each comparator and the signal amplification module is equal, and the preset discrimination threshold of each comparator is different.
Optionally, the multiple comparators are configured to acquire a leading edge point of the same current ranging signal to obtain multiple leading edge points; and acquiring the back edge point of the current ranging signal by the comparator corresponding to the minimum value in all preset discrimination thresholds.
Optionally, the signal analysis processing module is configured to determine a leading edge slope of a current ranging signal according to the multiple leading edge points, determine a signal width of the current ranging signal according to the trailing edge point and the leading edge point acquired by the target comparator, search a corresponding reference signal width in a preset relation reference table according to the leading edge slope of the current ranging signal, and filter noise of the current ranging signal according to the reference signal width and the signal width of the current ranging signal.
According to yet another aspect of the present application, there is also provided a computer readable medium having computer readable instructions stored thereon, the computer readable instructions being executable by a processor to implement the method as described above.
Compared with the prior art, the method has the advantages that the leading edge points of the current ranging signals are respectively acquired through the plurality of comparators of the scanning range finder to obtain the plurality of leading edge points; selecting a target comparator from a plurality of comparators of a scanning range finder, and acquiring a back edge point of a current ranging signal through the target comparator; determining the leading edge slope of the current ranging signal according to the plurality of leading edge points, and determining the signal width of the current ranging signal according to the trailing edge points and the leading edge points acquired by the target comparator; and searching the corresponding reference signal width in a preset relation reference table according to the leading edge slope of the current ranging signal, and filtering the noise point of the current ranging signal according to the reference signal width and the signal width of the current ranging signal. Therefore, noise generated by spot distortion can be effectively identified and filtered, and the accuracy of environment identification is improved.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:
FIG. 1 illustrates a prior art case of using a laser scanning rangefinder projecting to two panels that are independent of each other;
FIG. 2 is a schematic diagram showing a superimposed signal of spot distortion after the scan of FIG. 1;
FIG. 3 is a graph showing the scanning effect of continuous noise generated between the front and rear panels due to spot distortion;
FIG. 4 illustrates a schematic diagram of a scanning range finder for noise filtering of range signals provided in accordance with an aspect of the present application;
fig. 5 shows a representation of a normal signal of a single board of a laser scanning range finder in an embodiment of the present application;
FIG. 6 shows the scan effect after noise is identified and filtered out in an embodiment of the present application;
FIG. 7 illustrates a flow diagram of a method for noise filtering of ranging signals provided in accordance with an aspect of the present application;
FIG. 8 is a graph showing the slope of the leading edge of a normal signal versus the width of the signal for a laser scanning range finder in accordance with an embodiment of the present invention;
fig. 9 illustrates a method for filtering noise by a laser scanning range finder in an embodiment of the present application.
The same or similar reference numbers in the drawings identify the same or similar elements.
Detailed Description
The present application is described in further detail below with reference to the attached figures.
In a typical configuration of the present application, the terminal, the device serving the network, and the trusted party each include one or more processors (e.g., Central Processing Units (CPUs)), input/output interfaces, network interfaces, and memory.
The Memory may include volatile Memory in a computer readable medium, Random Access Memory (RAM), and/or nonvolatile Memory such as Read Only Memory (ROM) or flash Memory (flash RAM). Memory is an example of a computer-readable medium.
Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, Phase-Change RAM (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), electrically Erasable Programmable Read-Only Memory (EEPROM), flash Memory or other Memory technology, Compact Disc Read-Only Memory (CD-ROM), Digital Versatile Disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic Disk storage or other magnetic storage devices, or any other non-transmission medium, which can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include non-transitory computer readable media (transient media), such as modulated data signals and carrier waves.
FIG. 4 shows a schematic diagram of a scanning range finder for noise filtering of range signals according to one aspect of the present application, the scanning range finder comprising: the device comprises a photosensitive element 100, a signal conversion module 200, a signal amplification module 300, a comparator module 400, a time-to-digital converter module 500 and a signal analysis processing module 600; the photosensitive element 100 is configured to sense and receive an optical signal on a surface of a measured object, and convert the optical signal into an electrical signal; the photosensitive element 100 is connected to the signal conversion module 200, and the signal conversion module 200 is configured to convert a current signal excited by the electrical signal into a voltage signal; the signal conversion module 200 is connected to the signal amplification module 300, and the signal amplification module 300 is configured to amplify the voltage signal and simulate generation of signal noise floor; the comparator module 400 includes a plurality of identical comparators, all of which are commonly connected to the output end of the signal amplification module 300, and are configured to acquire the leading edge information and the trailing edge information of the signal output by the signal amplification module 300; the time-to-digital converter module 500 includes a plurality of time-to-digital converters, and is respectively connected to the output ends of the comparators, and is configured to convert the output information of the comparators into time-of-flight information; the signal analyzing and processing module 600 is configured to collect flight time information provided by each time-to-digital converter, and determine a ranging result according to the flight time information.
Here, the scanning rangefinder is optionally a laser scanning rangefinder of a robot, comprising: the optical sensing element 100 is used for sensing a received optical signal and converting the optical signal into an electrical signal, wherein the optical signal is also a single-plate signal, and refers to an optical signal obtained by projecting a laser spot onto the surface of a single measured object and reflecting the laser spot by the surface; the signal conversion module 200 is configured to convert a current signal excited by the light sensing element 100 into a voltage signal; the signal amplification module 300 is used for amplifying the amplitude of the voltage signal and simulating the generation of signal noise floor; the comparator module 400 is composed of a plurality of comparators with the same specification, and is commonly connected to the output end of the signal amplification module 300 for collecting the information of the leading edge and the trailing edge of the signal, and each independent comparator is respectively connected with the signal amplification module for respectively and independently collecting the signal output by the signal amplification module, wherein the leading edge refers to the rising edge of the signal, and the trailing edge refers to the falling edge of the signal; a Time-to-Digital Converter module 500, i.e., a TDC (Time-to-Digital Converter) module, which is composed of a plurality of TDCs (Time-to-Digital converters), and is respectively connected to the output ends of the comparators for converting the output information of the comparators into flight information; the signal analysis processing module 600 is configured to collect information of each TDC, and output a ranging result after comprehensive analysis processing; the flight information refers to the time of light propagation in a medium, the pulse laser is emitted as a starting point, the laser is propagated in the air, is projected on the surface of a measured object, is reflected back by the surface of the measured object, and is received by a photosensitive element as a termination point; time-of-flight measurements were made, specifically, distance from the scanner to the measured object =1/2 light speed time-of-flight.
In an embodiment of the present application, the time delays between each comparator and the signal amplification module are equal, and the preset discrimination thresholds of each comparator are different. Here, the preset discrimination thresholds of the individual comparators are not equal, and the setting method includes, but is not limited to, V1< V2< … … < VN, where V1, V2 and VN are the preset discrimination thresholds of comparator 1, comparator 2 and comparator N, so that the leading edge time of the signal can be sequentially acquired from low to high, and the slope of the leading edge of the signal can be fitted through the acquired series of leading edge times. Each independent comparator respectively and independently collects the signals output by the signal amplification module, and the time delay between each independent comparator and the signal amplification module is equal; therefore, the comparators can acquire the current signals at the same time, and the acquisition error is reduced.
In an embodiment of the present application, the multiple comparators are configured to acquire leading edge points of the same current ranging signal to obtain multiple leading edge points; and acquiring the back edge point of the current ranging signal by the comparator corresponding to the minimum value in all preset discrimination thresholds. Here, as shown in fig. 5, the comparator 1, the comparator 2, and the comparator … …, which have different preset discrimination thresholds, respectively collect leading edge coordinate points a1, a2, … …, and AN of the same signal, and the comparator 1 with the minimum preset discrimination threshold is used to collect a trailing edge point B of the signal; therefore, the collected information of the leading edge point and the trailing edge point is sent to the signal analysis processing module.
In connection with the foregoing embodiment, the signal analysis processing module is configured to determine a leading edge slope of a current ranging signal according to the leading edge points, determine a signal width of the current ranging signal according to the trailing edge points and the leading edge points acquired by the target comparator, search a corresponding reference signal width in a preset relation reference table according to the leading edge slope of the current ranging signal, and filter noise of the current ranging signal according to the reference signal width and the signal width of the current ranging signal. The leading edge slope of the signal is calculated after at least two or more comparators are used for collecting leading edge coordinate points of the signal, and the leading edge slope can be calculated through leading edge coordinate points A1, A2, … … and AN fitting; the signal width may be calculated using the leading edge point a1 and the trailing edge point B collected by the comparator with the minimum preset discrimination threshold, and the horizontal axis difference of B-a1 is the signal width, although it is understood that the calculation of the signal width includes, but is not limited to, the above-mentioned manner. The leading edge slope of the signal is monotonous relative to the signal width, the signal width is reduced from large in the process that the signal strength is weakened from strong, the leading edge slope of the signal is changed from small to large, and the leading edge slope and the signal width are changed synchronously, therefore, a leading edge slope-signal width reference table which is a corresponding relation between the leading edge slope and the signal width can be loaded firstly, after the signal is received, the comparator module collects each leading edge point of the signal and the comparator 1 collects the trailing edge of the signal at the same time, the leading edge slope Ki and the signal width Wi of the signal are calculated, the signal width W0 corresponding to Ki in the reference table is searched, Wi and W0 are compared, if Wi is larger than W0, namely when the actually collected signal width is larger than the normal signal width corresponding to the leading edge slope, the signal is the result of the superposition of the two signals, and the partial light spot is projected to the front plate, and (3) the distortion of the light spots caused by the projection of the residual light spots on the rear plate means that the signals generating the noise points are identified and need to be filtered, otherwise, the result is output. Therefore, noise generated by spot distortion can be effectively identified and filtered, and the accuracy of environment identification is improved.
By using the scanning range finder, noise can be identified and filtered, and a scanning effect graph after the noise is identified and filtered is obtained, as shown in fig. 6, when the actually acquired signal width is greater than the normal signal width corresponding to the leading edge slope, the signal is a result of superposition of two signals, a part of light spots are projected to the front plate correspondingly, and the rest of light spots are projected to the rear plate to cause light distortion, namely, the signal generating the noise is identified, so that a more accurate scanning effect graph is obtained.
Fig. 7 shows a flow diagram of a method for noise filtering of ranging signals, according to an aspect of the present application, the method comprising: step S11 to step S14, wherein,
in step S11, respectively acquiring leading edge points of a current ranging signal by a plurality of comparators of a scanning range finder to obtain a plurality of leading edge points; the scanning range finder is provided with a plurality of comparators, leading edge points of current ranging signals are respectively acquired through the comparators, the current ranging signals are signals obtained by currently measuring a measured object, and the leading edge points of the signals are rising edge points of the signals, so that a plurality of leading edge points acquired by different comparators can be obtained.
In step S12, selecting a target comparator from a plurality of comparators of the scanning range finder, and acquiring a trailing edge point of a current ranging signal through the target comparator; here, the comparators respectively collect leading edge points of the signals, such as leading edge coordinate points a1, a2, … …, AN of the same signal through the comparator 1, the comparator 2, and the comparator … … respectively; when the signal width is calculated, a back edge point is needed, so that one comparator can be selected to collect the back edge point of the current ranging signal.
In step S13, determining a leading edge slope of the current ranging signal according to the leading edge points, and determining a signal width of the current ranging signal according to the trailing edge points and the leading edge points acquired by the target comparator; here, the leading edge slope Ki of the current ranging signal is calculated by fitting a plurality of leading edge points acquired by different comparators, for example, if the selected target comparator is comparator 1, the signal width Wi of the current ranging signal is calculated according to the leading edge point a1 and the trailing edge point B acquired by comparator 1.
In step S14, a corresponding reference signal width is looked up in a preset relation reference table according to the leading edge slope of the current ranging signal, and noise of the current ranging signal is filtered according to the reference signal width and the signal width of the current ranging signal. The reference signal width W0 corresponding to the leading edge slope Ki obtained by calculation is searched in a preset relation reference table by utilizing the leading edge slope Ki obtained by calculation, so that the W0 and the Wi obtained by calculation are compared, the noise point of the current ranging signal is judged according to the comparison result, and the obtained noise point is filtered, wherein the preset relation reference table comprises the corresponding relation between the leading edge slope and the signal width.
In an embodiment of the present application, the method includes: and determining a preset relation reference table of the signal leading edge slope and the signal width of the scanned object. The preset relation reference table comprises a corresponding relation between the leading edge slope of the signal and the signal width, and the leading edge slope of the signal and the signal width are in a monotonous relation, so that the signal width is reduced from large in the process of weakening the signal strength from strong to small, the leading edge slope of the signal is increased from small to large, and the leading edge slope and the signal width are changed synchronously; therefore, the correspondence between the signal slope and the signal width can be determined by the time of the range scan of the scanned object.
Specifically, when the scanned object includes a scanned single board, determining the preset relation reference table, and acquiring a leading edge slope and a signal width of a signal in a signal strength state of each received signal by changing the signal strength of the received signal of the scanned single board; and determining a preset relation reference table according to the leading edge slopes and the signal widths of all the collected signals. Here, as shown in the relation diagram of the normal signal leading edge slope and the signal width of the laser scanning range finder shown in fig. 8, the leading edge slope and the signal width of the signal are collected in each signal strength state by changing the strength of the received signal with reference to the single-plate signal, so as to form a reference table with the leading edge slope as the horizontal axis and the signal width as the vertical axis.
In connection with the above embodiment, changing the signal strength of the received signal of the scanned board includes any one of the following manners or a combination of any several manners: changing the surface reflectivity of the scanned single plate by continuously changing the scanned single plate from white to black; keeping the surface reflectivity of the scanned single plate unchanged, and changing the continuous change of the driving current of the emitted light of the scanning range finder from strong to weak; the surface reflectivity of the scanned single plate is unchanged, and the effective luminous flux of the receiving end is changed. Here, changing the strength of the received signal may be obtained by continuously changing the reflectivity of the surface of the tested veneer, and the reflectivity of the surface of the tested veneer is kept changing from strong to weak, including but not limited to: continuously changing from white to black; the method can also be obtained by changing the power of the emitted light under the condition of keeping the surface reflectivity of the detected single board unchanged, including but not limited to changing the driving current of the emitted light from strong to weak; the method can also be obtained by changing the effective luminous flux of the receiving end under the condition of keeping the surface reflectivity of the measured single board constant and keeping the emitted light power constant, including but not limited to continuously changing the effective luminous flux by adopting a mode of closing or opening the aperture. The method can be realized by any one or any combination of the three changing modes; the surface of the single plate is the one which can make all the light spots fall on the surface of the measured object, when the light spots fall on the wall, the wall is the surface of the single plate, if only part of the light spots fall on the wall, the wall is not the surface of the single plate.
In an embodiment of the present application, in step S12, a preset discrimination threshold corresponding to each comparator of the scanning range finder is determined; and taking the comparator corresponding to the preset identification threshold value of the minimum value as a target comparator. Here, the scanning range finder includes a plurality of comparators with the same specification, the preset discrimination thresholds of the comparators are not equal, and the setting method may be V1< V2< … … VN, where V1, V2, and VN are the preset discrimination thresholds of comparator 1, comparator 2, and comparator N. The signal width includes, but is not limited to, the signal width calculated according to the acquisition determination using the comparator with the minimum preset discrimination threshold, such as the comparator (V1) corresponding to the preset discrimination threshold with the minimum value as the target comparator, so that the leading edge point and the trailing edge point acquired by the target comparator are obtained.
In an embodiment of the present invention, in step S14, when the signal width of the current ranging signal is greater than the reference signal width, the current ranging signal is determined to be noise. Here, each comparator collects each leading edge point of the signal and comparator 1 collects the trailing edge of the signal at the same time, calculate leading edge slope Ki and signal width Wi of the signal, look up signal width W0 corresponding to Ki in the reference table, compare Wi with W0, if Wi > W0, namely when the actually collected signal width is greater than the normal signal width corresponding to the leading edge slope, the signal is the result of two signal superpositions, it is the light spot distortion situation caused by projecting part of the light spot onto the front plate, the remaining light spot onto the back plate, namely the signal generating the noise point is identified, it needs to be filtered, otherwise, the result is output. Therefore, noise generated by spot distortion can be effectively identified and filtered, and the accuracy of environment identification is improved.
Fig. 9 shows a schematic diagram of a method for filtering noise points for a laser scanning range finder in AN embodiment of the present application, where a leading edge slope-signal width reference table is loaded first, after a signal is received, a plurality of comparators in a comparator module independently acquire each leading edge point of the signal respectively and comparator 1 acquires both leading edge point and trailing edge point of the signal, a leading edge slope Ki is calculated according to leading edge points a1 and a2 … … AN, a signal width Wi is calculated according to trailing edge point B and leading edge point a1, Ki in the reference table corresponds to a signal width W0, Wi and W0 are compared, if Wi > W0, it is determined that noise points are filtered, otherwise, it is determined as a normal point, and a result is output. Therefore, noise generated by spot distortion can be effectively identified and filtered, and the accuracy of environment identification is improved.
Furthermore, the present application also provides a computer readable medium, on which computer readable instructions are stored, the computer readable instructions being executable by a processor to implement the aforementioned method for noise filtering of a ranging signal.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
It should be noted that the present application may be implemented in software and/or a combination of software and hardware, for example, implemented using Application Specific Integrated Circuits (ASICs), general purpose computers or any other similar hardware devices. In one embodiment, the software programs of the present application may be executed by a processor to implement the steps or functions described above. Likewise, the software programs (including associated data structures) of the present application may be stored in a computer readable recording medium, such as RAM memory, magnetic or optical drive or diskette and the like. Additionally, some of the steps or functions of the present application may be implemented in hardware, for example, as circuitry that cooperates with the processor to perform various steps or functions.
In addition, some of the present application may be implemented as a computer program product, such as computer program instructions, which when executed by a computer, may invoke or provide methods and/or techniques in accordance with the present application through the operation of the computer. Program instructions which invoke the methods of the present application may be stored on a fixed or removable recording medium and/or transmitted via a data stream on a broadcast or other signal-bearing medium and/or stored within a working memory of a computer device operating in accordance with the program instructions. An embodiment according to the present application comprises an apparatus comprising a memory for storing computer program instructions and a processor for executing the program instructions, wherein the computer program instructions, when executed by the processor, trigger the apparatus to perform a method and/or a solution according to the aforementioned embodiments of the present application.
It will be evident to those skilled in the art that the present application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is obvious that the word "comprising" does not exclude other elements or steps, and the singular does not exclude the plural. The terms first, second, etc. are used to denote names, but not any particular order.
Claims (10)
1. A method for noise filtering of a ranging signal, the method comprising:
respectively acquiring leading edge points of a current ranging signal through a plurality of comparators of a scanning range finder to obtain a plurality of leading edge points;
selecting a target comparator from a plurality of comparators of a scanning range finder, and acquiring a back edge point of a current ranging signal through the target comparator;
determining the leading edge slope of the current ranging signal according to the plurality of leading edge points, and determining the signal width of the current ranging signal according to the trailing edge points and the leading edge points acquired by the target comparator;
and searching the corresponding reference signal width in a preset relation reference table according to the leading edge slope of the current ranging signal, and filtering the noise point of the current ranging signal according to the reference signal width and the signal width of the current ranging signal.
2. The method according to claim 1, characterized in that it comprises:
and determining a preset relation reference table of the signal leading edge slope and the signal width of the scanned object.
3. The method according to claim 2, wherein the scanned object comprises a scanned single board, and the determining of the reference table of the preset relationship between the slope of the leading edge of the signal and the width of the signal of the scanned object comprises:
changing the signal strength of the received signals of the scanned single board, and acquiring the leading edge slope and the signal width of the signals under the signal strength state of each received signal;
and determining a preset relation reference table according to the leading edge slopes and the signal widths of all the collected signals.
4. The method of claim 1, wherein selecting a target comparator from a plurality of comparators of a scanning range finder comprises:
determining a preset identification threshold corresponding to each comparator of the scanning range finder;
and taking the comparator corresponding to the preset identification threshold value of the minimum value as a target comparator.
5. The method of claim 1, wherein filtering noise of the current ranging signal according to the reference signal width and the signal width of the current ranging signal comprises:
and when the signal width of the current ranging signal is larger than the reference signal width, judging that the current ranging signal is noise.
6. The method according to claim 3, wherein changing the signal strength of the received signal of the scanned single board comprises any one of the following manners or any combination of the following manners:
changing the surface reflectivity of the scanned single plate by continuously changing the scanned single plate from white to black;
keeping the surface reflectivity of the scanned single plate unchanged, and changing the continuous change of the driving current of the emitted light of the scanning range finder from strong to weak;
the surface reflectivity of the scanned single plate is unchanged, and the effective luminous flux of the receiving end is changed.
7. A scanning range finder for noise filtering of range signals, the scanning range finder comprising: the device comprises a photosensitive element, a signal conversion module, a signal amplification module, a comparator module, a time-to-digital converter module and a signal analysis processing module;
the photosensitive element is used for sensing and receiving optical signals on the surface of the measured object and converting the optical signals into electric signals;
the photosensitive element is connected with the signal conversion module, and the signal conversion module is used for converting a current signal excited by the electric signal into a voltage signal;
the signal amplification module is used for amplifying the voltage signal and simulating the generation of signal noise floor;
the comparator module comprises a plurality of identical comparators, all of which are connected to the output end of the signal amplification module and used for acquiring leading edge points of signals output by the signal amplification module to obtain a plurality of leading edge points, selecting a target comparator from the identical comparators and acquiring a trailing edge point of a current ranging signal through the target comparator;
the time-to-digital converter module comprises a plurality of time-to-digital converters, is respectively connected to the output ends of the comparators and is used for converting the output information of the comparators into flight time information;
the signal analysis processing module is used for collecting flight time information provided by each time-to-digital converter and determining a distance measurement result according to the flight time information;
the signal analysis processing module is used for determining the leading edge slope of the current ranging signal according to the plurality of leading edge points, determining the signal width of the current ranging signal according to the trailing edge points and the leading edge points acquired by the target comparator, searching the corresponding reference signal width in a preset relation reference table according to the leading edge slope of the current ranging signal, and filtering the noise point of the current ranging signal according to the reference signal width and the signal width of the current ranging signal.
8. The scanning range finder of claim 7, wherein the time delay between each comparator and the signal amplification module is equal, and the predetermined discrimination threshold of each comparator is different.
9. The scanning range finder of claim 8, wherein the same comparators are used to acquire leading points of the same current ranging signal, resulting in multiple leading points; and taking the comparator corresponding to the minimum value in all preset discrimination thresholds as a target comparator, and acquiring the back edge point of the current ranging signal through the target comparator.
10. A computer readable medium having computer readable instructions stored thereon which are executable by a processor to implement the method of any one of claims 1 to 6.
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