CN112859100A - Laser radar, detection method and storage medium - Google Patents
Laser radar, detection method and storage medium Download PDFInfo
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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
- G01S17/32—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
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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
- G01S17/50—Systems of measurement based on relative movement of target
- G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
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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
- 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
- G01S7/491—Details of non-pulse systems
- G01S7/4912—Receivers
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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
- G01S7/491—Details of non-pulse systems
- G01S7/493—Extracting wanted echo signals
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Abstract
An embodiment of the present specification provides a laser radar, including at least: the device comprises a modulation module, a shunt processing module and a signal processing module; wherein, the modulation module includes: a modulation signal generating circuit and a light source modulator; the modulation signal generating circuit is used for mixing the generated baseband signal with the local oscillator signal to generate a modulation signal; the light source modulator is used for modulating the light source by using the modulation signal and loading the light source on the laser to obtain a laser signal; the shunt processing module is used for performing shunt processing on the laser signal and at least obtaining a transmitting signal and a receiving local oscillator signal; the signal processing module includes: a beam combiner and a signal processor; the beam combiner is used for carrying out frequency mixing processing on the echo signals and the received local oscillator signals to obtain difference frequency signals; and the signal processor is used for calculating and obtaining the characteristic information of the target object based on the difference frequency signal. The embodiment of the invention also provides a detection method and a storage medium based on the laser radar, and the anti-interference capability and the sensitivity are improved.
Description
Technical Field
The embodiment of the invention relates to the field of radar detection, in particular to a laser radar, a detection method based on the laser radar and a storage medium.
Background
Existing lidar, such as lidar, is a radar system that detects characteristic information of a target object by emitting a light beam; the working principle of the method is to emit laser signals, and then properly process received echo signals reflected from a target object to obtain characteristic information of the target object, such as the distance of the target object, the movement speed of the target object and the like.
However, a radar system corresponding to the existing laser radar cannot effectively modulate signals, and the anti-interference capability is poor; moreover, when the existing laser radar is used for detection, signals have no phase difference, and the inhibition capability on background light is poor.
Disclosure of Invention
The embodiment of the invention provides a laser radar, a detection method based on the laser radar and a storage medium, which can carry out coherent accumulation by utilizing the coherence of signals and effectively modulate the signals, so that the anti-interference capability is improved, and the sensitivity of the laser radar is improved.
The embodiment of the invention provides a laser radar, which at least comprises: the device comprises a modulation module, a shunt processing module and a signal processing module; wherein,
the modulation module at least comprises: a modulation signal generating circuit and a light source modulator; the modulation signal generating circuit is used for mixing the generated baseband signal with a local oscillator signal to generate a modulation signal; the light source modulator is used for modulating a light source by using a modulation signal and loading the light source on laser to obtain a laser signal;
the branch processing module is used for carrying out branch processing on the laser signal and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar;
the signal processing module at least comprises: a beam combiner and a signal processor; the beam combiner is used for carrying out frequency mixing processing on the echo signal of the acquired transmitting signal after passing through a target object in the target area and the receiving local oscillator signal to obtain a difference frequency signal; and the signal processor is used for calculating and obtaining the characteristic information of the target object based on the difference frequency signal.
In the embodiment of the invention, the laser radar is a linear frequency modulation continuous wave LFMCW solid-state area array laser radar.
In an embodiment of the present invention, the signal processing module further includes: an area array photoelectric sensor; the area array photoelectric sensor is used for carrying out digital conversion processing on the difference frequency signals acquired from the beam combiner so as to transmit the difference frequency signals subjected to digital conversion processing to the signal processor.
In the embodiment of the present invention, the signal processor is further configured to perform time-frequency domain conversion processing on the difference frequency signal, and calculate to obtain the feature information of the target object based on at least the frequency spectrum information of the difference frequency signal after the conversion processing.
In an embodiment of the present invention, the modulation signal generating circuit includes: the direct digital synthesis DDS circuit comprises a direct digital synthesis DDS circuit, a local oscillator circuit and a frequency conversion circuit; wherein,
the direct digital synthesis DDS circuit is used for generating baseband signals; the local oscillation circuit is used for generating local oscillation signals; the frequency conversion circuit is used for mixing the baseband signal and the local oscillator signal to generate a modulation signal.
In the embodiment of the present invention, the direct digital synthesis DDS circuit is further configured to generate a linear modulated continuous wave, and use the linear modulated continuous wave as a baseband signal.
In the embodiment of the invention, the direct digital synthesis DDS circuit is also used for generating a triangular wave baseband signal or a sawtooth wave baseband signal.
In an embodiment of the present invention, the laser radar further includes a receiving module, configured to receive an echo signal of the transmission signal after passing through a target object in the target area, so as to transmit the echo signal to the beam combiner.
The embodiment of the invention also provides a detection method based on the laser radar, which comprises the following steps:
mixing the generated baseband signal with a local oscillator signal to generate a modulation signal;
modulating the modulation signal and loading the modulation signal to laser to obtain a laser signal, carrying out shunt processing on the laser signal, and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar;
and performing frequency mixing processing on the acquired transmitting signal and the receiving local oscillator signal after passing through the target object in the target area, so as to calculate and obtain characteristic information of the target object at least based on a difference frequency signal obtained after the frequency mixing processing.
An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the following steps:
mixing the generated baseband signal with a local oscillator signal to generate a modulation signal;
modulating the modulation signal and loading the modulation signal to laser to obtain a laser signal, carrying out shunt processing on the laser signal, and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar;
and performing frequency mixing processing on the acquired transmitting signal and the receiving local oscillator signal after passing through the target object in the target area, so as to calculate and obtain characteristic information of the target object at least based on a difference frequency signal obtained after the frequency mixing processing.
The laser radar, the detection method based on the laser radar and the storage medium of the embodiment of the invention are characterized in that the laser radar at least comprises: the device comprises a modulation module, a shunt processing module and a signal processing module; wherein the modulation module at least comprises: a modulation signal generating circuit and a light source modulator; the modulation signal generating circuit is used for mixing the generated baseband signal with a local oscillator signal to generate a modulation signal; the light source modulator is used for modulating a light source by using a modulation signal and loading the light source on laser to obtain a laser signal; the branch processing module is used for carrying out branch processing on the laser signal and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar; the signal processing module at least comprises: a beam combiner and a signal processor; the beam combiner is used for carrying out frequency mixing processing on the echo signal of the acquired transmitting signal after passing through a target object in the target area and the receiving local oscillator signal to obtain a difference frequency signal; and the signal processor is used for calculating and obtaining the characteristic information of the target object based on the difference frequency signal. Therefore, coherent accumulation can be carried out by utilizing the coherence of the signals, the signals are effectively modulated, the anti-interference capability is improved, and the sensitivity of the laser radar is improved.
Drawings
Fig. 1 is a first schematic flow chart illustrating an implementation of a detection method according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a laser radar according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of an implementation flow of the detection method according to the embodiment of the present invention.
Fig. 4 is a schematic diagram of a component structure in a specific application scenario according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of the operation principle of the LFMCW according to the embodiment of the present invention.
Detailed Description
In order to better understand the technical solutions, the technical solutions of the embodiments of the present specification are described in detail below with reference to the drawings and specific embodiments, and it should be understood that the specific features of the embodiments and embodiments of the present specification are detailed descriptions of the technical solutions of the embodiments of the present specification, and are not limitations of the technical solutions of the present specification, and the technical features of the embodiments and embodiments of the present specification may be combined with each other without conflict.
The embodiment of the invention provides a detection method based on a laser radar, and particularly relates to a laser radar which is a Linear Frequency Modulated Continuous Wave (LFMCW) laser radar in practical application, or the laser radar is an LFMCW solid state area array laser radar.
Here, the detection method according to the embodiment of the present invention may be configured to emit continuous waves with varying frequencies in a linear sweep period, where a certain frequency difference exists between an echo signal of an emitted signal reflected by a target object and the emitted signal, and thus, characteristic information between the target object and the laser radar, such as distance information and radial velocity information, may be obtained by measuring the frequency difference.
The detection method of the embodiment of the invention adopts a linear frequency modulation continuous wave mechanism, and the receiving channel can carry out coherent accumulation by utilizing the coherence of signals, thus improving the signal processing gain, improving the sensitivity of the receiving channel and reducing the transmitting power. Meanwhile, the method provided by the embodiment of the invention can be used for inhibiting background noise such as sunlight by utilizing the coherence of the echo signals, so that the inhibiting capability of the background light is improved, and the outdoor detection capability of the laser radar is improved.
Moreover, the method of the embodiment of the invention can generate a bandwidth linear modulation frequency sweep signal, for example, a Direct Digital Synthesis (DDS) circuit is used for generating a triangular wave or sawtooth wave baseband signal, so that the frequency modulation linearity of the frequency modulation linearity is ensured, the frequency conversion and the frequency modulation are flexibly realized, the anti-interference capability of a system is improved, and the concurrent processing capability of a plurality of laser radars implementing the method of the embodiment of the invention when in use is improved.
Furthermore, after the method provided by the embodiment of the invention is applied to the LFMCW solid-state area array laser radar, the average power of the transmitted signal is equal to the peak power, and the method can be realized only by adopting a low-power device, so that the method has the advantages of relatively simple structure, small size, light weight, low cost and the like.
Specifically, fig. 1 is a schematic flow chart of an implementation process of a detection method based on a laser radar according to an embodiment of the present invention, and as shown in fig. 1, the detection method includes:
step 101: and mixing the generated baseband signal with the local oscillator signal to generate a modulation signal.
In a specific example, the step 101 may specifically be: and generating a linear modulation continuous wave by using a DDS circuit, and taking the linear modulation continuous wave as a baseband signal. Further, the step 101 generates a triangular wave baseband signal or a sawtooth wave baseband signal by using a DDS circuit.
In practical applications, the local oscillation signal may be generated by a local oscillation circuit.
Step 102: and modulating the modulation signal and loading the modulation signal to laser to obtain a laser signal.
Step 103: carrying out shunt processing on the laser signal, and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar.
For example, after a baseband signal generated by the DDS circuit is mixed with a local oscillator signal, a modulation signal is generated to modulate the light source, and the modulation signal is loaded to the laser to complete the modulation of the light source and obtain a laser signal; and then, splitting the laser signal, wherein one path is used as a transmitting signal and radiates to a covered space domain, and the other path is used as a receiving local oscillator signal of a receiving signal.
Step 104: and performing frequency mixing processing on the acquired transmitting signal and the receiving local oscillator signal after passing through the target object in the target area, so as to calculate and obtain characteristic information of the target object at least based on a difference frequency signal obtained after the frequency mixing processing.
In the embodiment of the present invention, the target object refers to an object that appears in the measurement range of the laser radar.
Here, the echo signal is a signal in which the transmission signal is reflected back after passing through a target object.
In the embodiment of the invention, the frequency of the difference frequency signal generated by mixing is linearly related to the detection distance, so that the characteristic information of the target object, such as distance, speed and the like, can be calculated by performing time-frequency domain conversion through back-end processing.
In practical application, the laser radar performs heterodyne processing on the echo signal and the received local oscillator signal to generate a difference frequency signal, performs digital processing, such as digital conversion processing and time-frequency domain conversion processing, on the difference frequency signal, and then calculates to obtain characteristic information of the target object based on at least frequency spectrum information of the difference frequency signal after the conversion processing. For example, in a specific example, after the difference frequency signal is obtained through the frequency mixing process, low-pass filtering is performed, the filtered difference frequency signal is converted into a Digital signal through an Analog-to-Digital converter (ADC), time-frequency-domain conversion is performed through a Fast Fourier Transform (FFT), and further, based on the frequency spectrum information of the converted signal, the frequency point and the doppler frequency shift of the difference frequency signal are calculated, so as to calculate the distance and the speed of the target object.
Therefore, the detection method according to the embodiment of the present invention can emit continuous waves with variable frequencies in a linear sweep period, and a certain frequency difference exists between an echo signal of an emitted signal reflected by a target object and the emitted signal, so that characteristic information between the target object and the laser radar, such as distance information and radial velocity information, can be obtained by measuring the frequency difference.
In addition, the detection method of the embodiment of the invention adopts a linear frequency modulation continuous wave mechanism, and the receiving channel can carry out coherent accumulation by utilizing the coherence of signals, thereby improving the signal processing gain, improving the sensitivity of the receiving channel and reducing the transmitting power. Meanwhile, by utilizing the coherence of the echo signals, the method can also suppress background noise such as sunlight, so that the suppression capability of the background light is improved, and the outdoor detection capability of the laser radar is improved.
Furthermore, the method of the embodiment of the invention can generate a bandwidth linear modulation frequency sweep signal, for example, a DDS circuit is used for generating a triangular wave or sawtooth wave baseband signal, so that the frequency modulation linearity of the frequency modulation linearity is ensured, the frequency conversion and the frequency modulation are flexibly realized, the anti-interference capability of the system is improved, and the concurrent processing capability of a plurality of laser radars implementing the method of the embodiment of the invention when in use is improved.
Based on the same inventive concept as the method embodiment, an embodiment of the present invention provides a laser radar, as shown in fig. 2, the laser radar at least includes: a modulation module 21, a shunt processing module 22, and a signal processing module 23; wherein,
the modulation module 21 comprises at least: a modulation signal generating circuit and a light source modulator; the modulation signal generating circuit is used for mixing the generated baseband signal with a local oscillator signal to generate a modulation signal; the light source modulator is used for modulating a light source by using a modulation signal and loading the light source on laser to obtain a laser signal;
the branch processing module 22 is configured to perform branch processing on the laser signal, and obtain at least a transmission signal and a reception local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar; the splitting processing module may be implemented by a splitter.
The signal processing module 23 at least comprises: a beam combiner and a signal processor; the beam combiner is used for carrying out frequency mixing processing on the echo signal of the acquired transmitting signal after passing through a target object in the target area and the receiving local oscillator signal to obtain a difference frequency signal; and the signal processor is used for calculating and obtaining the characteristic information of the target object based on the difference frequency signal.
In a specific example, the lidar is a chirped continuous wave LFMCW solid state area array lidar. Therefore, after the LFMCW solid-state area array laser radar is adopted, the average power of the transmitted signal is equal to the peak power, and the method can be realized only by adopting a low-power device, so that the LFMCW solid-state area array laser radar has the advantages of relatively simple structure, small size, light weight, low cost and the like. And moreover, the system also has the characteristics of strong anti-interference capability and high resolution, does not have any mechanical rotating part, has strong stability and is suitable for mass production.
In practical application, in this embodiment, the laser radar further includes a transmitting module, configured to radiate a transmission signal to a covered airspace. In particular, the transmitting module may be implemented by a transmitting antenna.
Further, the lidar further comprises a receiving module, configured to receive an echo signal of the transmission signal after passing through a target object in the target area, so as to transmit the echo signal to the beam combiner. Here, the echo signal is a signal that is reflected back after the transmission signal passes through a target object; the target object refers to an object that appears within the measurement range of the lidar.
In particular, the receiving module may be implemented by a receiving antenna.
In a specific example, the signal processing module 23 further includes: an area array photoelectric sensor; the area array photoelectric sensor is used for carrying out digital conversion processing on the difference frequency signals acquired from the beam combiner so as to transmit the difference frequency signals subjected to digital conversion processing to the signal processor.
In a specific example, the signal processor is further configured to perform time-frequency domain conversion processing on the difference frequency signal, and calculate feature information of the target object based on at least the spectrum information of the difference frequency signal after the conversion processing.
In a specific example, the modulation signal generation circuit includes: the direct digital synthesis DDS circuit comprises a direct digital synthesis DDS circuit, a local oscillator circuit and a frequency conversion circuit; wherein, the direct digital synthesis DDS circuit is used for generating baseband signals; the local oscillation circuit is used for generating local oscillation signals; the frequency conversion circuit is used for mixing the baseband signal and the local oscillator signal to generate a modulation signal. In practical applications, the frequency conversion circuit is an up-conversion circuit, and is used for performing up-conversion processing on a triangular baseband signal or a sawtooth baseband signal generated by the DDS circuit and the local oscillator signal, for example.
In another specific example, the direct digital synthesis DDS circuit is further configured to generate a linear modulated continuous wave and use the linear modulated continuous wave as a baseband signal; specifically, the direct digital synthesis DDS circuit is further configured to generate a triangular baseband signal or a sawtooth baseband signal.
Therefore, the laser radar according to the embodiment of the present invention can emit continuous waves with varying frequencies within a linear sweep period, and a certain frequency difference exists between an echo signal of an emitted signal reflected by a target object and the emitted signal, so that characteristic information between the target object and the laser radar, such as distance information and radial velocity information, can be obtained by measuring the frequency difference.
In addition, the laser radar of the embodiment of the invention adopts a linear frequency modulation continuous wave mechanism, and the receiving channel can carry out coherent accumulation by utilizing the coherence of signals, so that the signal processing gain is improved, the sensitivity of the receiving channel is improved, and the transmitting power is reduced. Meanwhile, by utilizing the coherence of the echo signals, the method can also suppress background noise such as sunlight, so that the suppression capability of the background light is improved, and the outdoor detection capability of the laser radar is improved.
Furthermore, the laser radar of the embodiment of the invention can generate a bandwidth linear modulation frequency sweep signal, for example, a DDS circuit is used for generating a triangular wave or sawtooth wave baseband signal, so that the frequency modulation linearity of the frequency modulation linearity is ensured, the frequency conversion and the frequency modulation are flexibly realized, the anti-interference capability of a system is improved, and the concurrent processing capability of a plurality of laser radars implementing the method of the embodiment of the invention when in use is improved.
Here, it should be noted that: the descriptions of the embodiments of the apparatus are similar to the descriptions of the methods, and have the same advantages as the embodiments of the methods, and therefore are not repeated herein. For technical details that are not disclosed in the embodiments of the apparatus of the present invention, those skilled in the art should refer to the description of the embodiments of the method of the present invention to understand, and for brevity, will not be described again here.
The following examples further illustrate the present invention. As shown in fig. 3 and 4, the detection method according to the embodiment of the present invention includes:
step 301: the DDS circuit 11 generates a triangular or sawtooth baseband signal.
In practical application, the triangular wave or sawtooth wave baseband signal generated by the DDS circuit is also synchronously transmitted to the signal processor 13, so that the signal processor 13 performs time-frequency domain conversion processing on the difference frequency signal according to the synchronous baseband signal.
Step 302: the baseband signal generated by the DDS circuit 11 is mixed with the local oscillator signal generated by the local oscillator circuit 10, for example, by an up-conversion circuit 9 to perform an up-conversion process, thereby generating a modulated signal.
Step 303: based on the light source modulator 2, the light source 1 is modulated by the modulation signal, and the modulation signal is loaded on the light source 1 to complete modulation of the light source 1, so as to obtain the laser signal.
Step 304: the laser signal is split by the beam splitter 3 to obtain two paths of signals, which are respectively a transmitting signal and a receiving local oscillation signal as a receiving signal.
Specifically, one path of the transmission signal is processed by the beam expander 4 and then transmitted to the transmitting antenna 5 to be radiated to the airspace covered by the laser radar. And the other path is used as a receiving local oscillation signal and is sent to a beam combiner 7 of a receiving channel. Specifically, in practical application, before sending a path of signal serving as a received local oscillator signal to the beam combiner 7, the signal may also be processed by the beam expander 8, and then the signal processed by the beam expander 8 is sent to the beam combiner 7.
Here, it should be noted that the component diagram shown in fig. 4 is not intended to limit the embodiment of the present invention, and in practical applications, the component diagram may also be increased or decreased according to the actual scene requirement, the signal processing requirement, or the component processing capability.
Step 305: the transmission signal is reflected back to the callback signal after meeting the target object, and the receiving antenna 6 receives the echo signal.
Step 306: the echo signal is mixed with the received local oscillation signal obtained after the splitting in step 304 through the beam combiner 7, for example, down-conversion is performed to generate a difference frequency signal, and the difference frequency signal is subjected to digital conversion through the area array photoelectric sensor 12, and is sent to the signal processor 12 after the conversion.
Step 307: the signal processor 12 performs time-frequency domain conversion on the difference frequency signal processed in step 305 according to a triangular wave or sawtooth wave baseband signal synchronized by the DDS circuit 11 to obtain frequency spectrum information of the difference frequency signal, and calculates a frequency point and a doppler shift of the difference frequency signal to determine a distance and a speed of a target object.
In the following, a specific method for calculating the distance of the target object is described in detail, and as shown in fig. 5, the specific calculation method includes:
for a target object far away from the laser radar, the intermediate frequency signal after the echo signal is mixed with the received local oscillator signal is at t1～t2Has a frequency value of fb+＝f0-fdAnd at t3～t4Has a frequency value of fb-＝f0+fdCalculating to obtain the actual difference frequency f0And Doppler frequency fdAnd then the distance and the movement speed of the target object are obtained.
Taking the calculated distance as an example, assume that the chirp rate of the triangular baseband signal generated by the DDS is: (f)H-fL) And T, the time Deltat required for the transmitting signal to be received by the receiving antenna after being reflected by the target object is as follows:
the distance of the target object can be calculated based on the above formula (1) as follows:
in the above formula, T represents the modulation period, and c represents the light speed. Similarly, the speed of the target object may be further calculated based on a similar principle, which is not described in detail in the embodiments of the present invention. It should be noted that the target object according to the embodiment of the present invention may be a moving object with respect to the lidar or an object in a stationary state with respect to the lidar, and the embodiment of the present invention is not limited thereto.
Based on the same inventive concept as the above method embodiment, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, which, when executed by a processor, implements the steps of:
mixing the generated baseband signal with a local oscillator signal to generate a modulation signal;
modulating the modulation signal and loading the modulation signal to laser to obtain a laser signal, carrying out shunt processing on the laser signal, and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar;
and performing frequency mixing processing on the acquired transmitting signal and the receiving local oscillator signal after passing through the target object in the target area, so as to calculate and obtain characteristic information of the target object at least based on a difference frequency signal obtained after the frequency mixing processing.
In this embodiment, when executed by the processor, the computer program further implements the following steps:
generating a linearly modulated continuous wave and using the linearly modulated continuous wave as a baseband signal.
In this embodiment, when executed by the processor, the computer program further implements the following steps:
and generating a triangular wave baseband signal or a sawtooth wave baseband signal.
In this embodiment, when executed by the processor, the computer program further implements the following steps:
at least carrying out digital conversion processing and time-frequency domain conversion processing on the difference frequency signals;
and calculating to obtain the characteristic information of the target object at least based on the frequency spectrum information of the difference frequency signal after conversion processing.
For the storage medium provided in the embodiments of the present invention, the specific implementation manner of the above steps or other steps that can be implemented when the computer program is executed by the processor is referred to the description of the above embodiments, and details are not repeated here.
The laser radar, the detection method thereof and the storage medium provided by the embodiment of the invention can be widely applied to various scenes, such as unmanned vehicles, intelligent warehouses, industrial robots, service robots and the like.
The description has been presented with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the description. 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 processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means 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 processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means 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 processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus 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 specification have been described, additional variations and modifications in those 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 changes and modifications that fall within the scope of the specification.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present specification without departing from the spirit and scope of the specification. Thus, if such modifications and variations of the present specification fall within the scope of the claims of the present specification and their equivalents, the specification is intended to include such modifications and variations.
Claims (10)
1. Lidar characterized by at least comprising: the device comprises a modulation module, a shunt processing module and a signal processing module; wherein,
the modulation module at least comprises: a modulation signal generating circuit and a light source modulator; the modulation signal generating circuit is used for mixing the generated baseband signal with a local oscillator signal to generate a modulation signal; the light source modulator is used for modulating a light source by using a modulation signal and loading the light source on laser to obtain a laser signal;
the branch processing module is used for carrying out branch processing on the laser signal and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar;
the signal processing module at least comprises: a beam combiner and a signal processor; the beam combiner is used for carrying out frequency mixing processing on the echo signal of the acquired transmitting signal after passing through a target object in the target area and the receiving local oscillator signal to obtain a difference frequency signal; and the signal processor is used for calculating and obtaining the characteristic information of the target object based on the difference frequency signal.
2. The lidar of claim 1, wherein the lidar is a chirped continuous wave LFMCW solid state area array lidar.
3. The lidar of claim 2, wherein the signal processing module further comprises: an area array photoelectric sensor; the area array photoelectric sensor is used for carrying out digital conversion processing on the difference frequency signals acquired from the beam combiner so as to transmit the difference frequency signals subjected to digital conversion processing to the signal processor.
4. Lidar according to claim 1,
the signal processor is further configured to perform time-frequency domain conversion processing on the difference frequency signal, and calculate to obtain the characteristic information of the target object based on at least the frequency spectrum information of the difference frequency signal after the conversion processing.
5. The lidar of claim 1, wherein the modulated signal generating circuit comprises: the direct digital synthesis DDS circuit comprises a direct digital synthesis DDS circuit, a local oscillator circuit and a frequency conversion circuit; wherein,
the direct digital synthesis DDS circuit is used for generating baseband signals; the local oscillation circuit is used for generating local oscillation signals; the frequency conversion circuit is used for mixing the baseband signal and the local oscillator signal to generate a modulation signal.
6. Lidar according to claim 5,
the direct digital synthesis DDS circuit is also used for generating a linear modulation continuous wave and taking the linear modulation continuous wave as a baseband signal.
7. The lidar of claim 5 or 6, wherein the Direct Digital Synthesis (DDS) circuit is further configured to generate a triangular baseband signal or a sawtooth baseband signal.
8. The lidar of claim 1, further comprising a receiving module configured to receive an echo signal of the transmit signal after passing through a target object in the target area to transmit the echo signal to the beam combiner.
9. A lidar based detection method, the method comprising:
mixing the generated baseband signal with a local oscillator signal to generate a modulation signal;
modulating the modulation signal and loading the modulation signal to laser to obtain a laser signal, carrying out shunt processing on the laser signal, and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar;
and performing frequency mixing processing on the acquired transmitting signal and the receiving local oscillator signal after passing through the target object in the target area, so as to calculate and obtain characteristic information of the target object at least based on a difference frequency signal obtained after the frequency mixing processing.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of:
mixing the generated baseband signal with a local oscillator signal to generate a modulation signal;
modulating the modulation signal and loading the modulation signal to laser to obtain a laser signal, carrying out shunt processing on the laser signal, and at least obtaining a transmitting signal and a receiving local oscillator signal; the transmitting signal is used for transmitting to a target area which can be radiated by the laser radar;
and performing frequency mixing processing on the acquired transmitting signal and the receiving local oscillator signal after passing through the target object in the target area, so as to calculate and obtain characteristic information of the target object at least based on a difference frequency signal obtained after the frequency mixing processing.
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