CN111638525A

CN111638525A - Laser ranging device and laser ranging method

Info

Publication number: CN111638525A
Application number: CN202010708798.0A
Authority: CN
Inventors: 毛庆洲; 刘新; 周昊; 张维通; 洪骄阳
Original assignee: Wuhan Luojia Yiyun Photoelectric Technology Co ltd
Current assignee: Wuhan Luojia Yiyun Photoelectric Technology Co ltd
Priority date: 2020-07-21
Filing date: 2020-07-21
Publication date: 2020-09-08

Abstract

The application provides a laser ranging device and a laser ranging method. The device includes: a laser; the device comprises a transmitting optical component, a receiving optical component, a first photoelectric detector, a second photoelectric detector and a control module, wherein the transmitting optical component, the receiving optical component, the first photoelectric detector, the second photoelectric detector and the control module are arranged on an echo path of the laser reflected back by a target object. The control module is respectively electrically connected with the laser, the first photoelectric detector and the second photoelectric detector, and is used for triggering the laser and acquiring the distance of the target object based on a first electric signal output by the first photoelectric detector and a second electric signal output by the second photoelectric detector. Compared with the prior art, the time of laser output can be accurately determined through the seed light which is the same as the laser at the same moment, and further the distance measurement precision is higher.

Description

Laser ranging device and laser ranging method

Technical Field

The application relates to the technical field of laser radars, in particular to a laser ranging device and a laser ranging method.

Background

The laser radar is a radar system that detects a characteristic amount such as a position and a velocity of a target by emitting a laser beam. The working principle is to transmit a detection signal (laser beam) to a target, then compare the received signal (target echo) reflected from the target with the transmitted signal, and after appropriate processing, the distance of the target can be obtained. However, the measured distance is not accurate enough since the time information of the transmitted signal cannot be accurately determined.

Disclosure of Invention

An object of the embodiments of the present application is to provide a laser ranging apparatus and a laser ranging method, so as to solve the problem of "the measured distance is not accurate enough because the time information of the transmitted signal cannot be accurately determined".

The invention is realized by the following steps:

in a first aspect, an embodiment of the present application provides a laser ranging device, including: a laser; for emitting laser light and transmitting the same seed light as the laser light while emitting the laser light; the emission optical assembly is arranged in the light emitting direction of the laser; the emission optical component is used for adjusting the direction of the laser; the receiving optical assembly is arranged on an echo path of the laser reflected by the target object; a first photodetector connected to the laser for receiving the seed light and outputting a first electrical signal based on the seed light; the second photoelectric detector is arranged on a light condensation path of the receiving optical assembly and used for receiving the echo after being condensed by the receiving optical assembly and outputting a second electric signal based on the echo; and the control module is electrically connected with the laser, the first photoelectric detector and the second photoelectric detector respectively, and is used for triggering the laser and acquiring the distance of the target object based on the first electric signal and the second electric signal.

In the embodiment of the present application, when the laser emits the laser light to the target object, the laser device simultaneously transmits the same seed light as the laser light emitted by the laser device to the first photodetector. The first photoelectric detector converts the optical signal of the seed light into a first electric signal and outputs the first electric signal to the control module, and the second photoelectric detector converts the received optical signal of the echo returned by the target object into a second electric signal and outputs the second electric signal to the control module. And then the control module obtains the accurate distance of the target object based on the first electric signal and the second electric signal. Compared with the prior art, the time of laser output can be accurately determined through the seed light which is the same as the laser at the same moment, and further the distance measurement precision is higher.

With reference to the technical solution provided by the first aspect, in some possible implementations, the control module includes: the device comprises a main controller and an FPGA chip; the main controller is electrically connected with the FPGA chip; the main controller is electrically connected with the laser, and is used for triggering the laser; the FPGA chip is electrically connected with the first photoelectric detector and the second photoelectric detector respectively, and is used for processing the first electric signal in parallel, processing the second electric signal in parallel and acquiring the distance of the target object based on the first electric signal and the second electric signal.

In this embodiment, the FPGA chip may process a first electrical signal output by the first photodetector, process a second electrical signal output by the second photodetector, and obtain the distance to the target object based on the first electrical signal and the second electrical signal. By parallel processing of the data, the processing time can be reduced.

With reference to the technical solution provided by the first aspect, in some possible implementations, the emission optical component includes: the angle of the first reflector is adjustable, and the first reflector is arranged in the light emitting direction of the laser.

In this application embodiment, the light-emitting direction of regulation laser that can be nimble through first speculum improves the flexibility of laser rangefinder range finding.

In combination with the technical solution provided by the first aspect, in some possible implementation manners, the laser ranging device further includes a servo motor, the servo motor is electrically connected to the control module, the servo motor is connected to the first reflecting mirror, and the servo motor is configured to receive a rotation instruction sent by the control module, so as to control the first reflecting mirror to rotate.

In the embodiment of the application, the servo motor connected with the first reflecting mirror is arranged, so that the automatic adjustment of the angle of the first reflecting mirror is facilitated.

With reference to the technical solution provided by the first aspect, in some possible implementation manners, the laser distance measuring device includes a second reflecting mirror, the second reflecting mirror is disposed between the laser and the first reflecting mirror, a through hole is disposed in a center of the second reflecting mirror, and laser emitted by the laser is incident into the reflecting mirror through the through hole and then is incident into the target object; the echo reflected by the object is reflected by the first mirror and the second mirror into the receiving optical assembly.

In the embodiment of the present application, by providing the second reflecting mirror, the beam range of the received echo can be increased.

With reference to the technical solution provided by the first aspect, in some possible implementations, the laser is a pulse laser.

In combination with the technical solution provided by the first aspect, in some possible implementation manners, the control module is further configured to trigger the laser to emit waveforms with different pulse widths in each preset time interval.

In the embodiment of the application, continuous pulse trigger measurement can be realized by triggering the pulse laser to emit waveforms with different pulse widths in each preset time interval, and the next laser beam does not need to be emitted after the echo signal returned from the target by the previous laser is received.

In a second aspect, an embodiment of the present application provides a laser ranging method, which is applied to a control module in the laser ranging apparatus provided in the first aspect, where the laser is a pulse laser, and the method includes: receiving a first electrical signal output by the first photodetector and receiving a second electrical signal output by the second photodetector; performing Gaussian fitting on the seed optical waveform corresponding to the first electrical signal and performing Gaussian fitting on the echo waveform corresponding to the second electrical signal; acquiring the center position of the fitted seed optical waveform and the center position of the fitted echo waveform; and acquiring the distance of the target object based on the center position of the fitted seed light waveform and the center position of the fitted echo waveform.

In the embodiment of the application, because the waveform has an error in the propagation process, the seed light waveform and the echo waveform are corrected by the gaussian waveform fitting algorithm, so that the distance value of the target object obtained by the seed light waveform and the echo waveform is more accurate.

With reference to the technical solution provided by the second aspect, in some possible implementation manners, the receiving a first electrical signal output by the first photodetector and receiving a second electrical signal output by the second photodetector includes: receiving a plurality of first electrical signals output by the first photodetector and receiving a plurality of second electrical signals output by the second photodetector; correspondingly, performing gaussian fitting on the seed optical waveform corresponding to the first electrical signal and performing gaussian fitting on the echo waveform corresponding to the second electrical signal includes: acquiring a target seed optical waveform and a target echo waveform which have the same waveform in a seed optical waveform corresponding to the first electric signal and an echo waveform corresponding to the second electric signal; performing Gaussian fitting on the target seed light waveform and the target echo waveform; correspondingly, obtaining the distance of the target object based on the center position of the fitted seed light waveform and the center position of the fitted echo waveform includes: and acquiring the distance of the target object based on the center position of the fitted target seed optical waveform and the center position of the fitted target echo waveform.

The embodiment of the application provides a continuous multi-pulse ranging mode, in the mode, a control module triggers a laser to emit waveforms with different pulse widths within a preset time interval, and then the waveforms with the same pulse width are processed, namely, each seed light and an echo signal corresponding to the seed light can be distinguished through the pulse width of the seed light. By the mode, continuous pulse trigger measurement is realized, and the next laser beam is not required to be emitted after the echo signal returned from the target object by the previous laser is received.

With reference to the technical solution provided by the second aspect, in some possible implementation manners, before performing gaussian fitting on the seed optical waveform corresponding to the first electrical signal and performing gaussian fitting on the echo waveform corresponding to the second electrical signal, the method further includes: acquiring a maximum value m of a waveform in the first electric signal and a maximum value n of a waveform in the second electric signal; and filtering the waveform of which the peak value is smaller than m/2 in the first electric signal to obtain the seed optical waveform, and filtering the waveform of which the peak value is smaller than n/2 in the second electric signal to obtain the echo waveform.

Compared with a fixed threshold filtering method in the prior art, the filtering method using the half-wave height as the threshold has better flexibility and accuracy.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.

Fig. 1 is a block diagram of a laser ranging device according to an embodiment of the present disclosure.

Fig. 2 is a schematic structural diagram of a laser distance measuring device according to an embodiment of the present application.

Fig. 3 is a schematic structural diagram of another laser distance measuring device according to an embodiment of the present application.

Fig. 4 is a block diagram of another laser ranging device according to an embodiment of the present disclosure.

Fig. 5 is a waveform diagram including 4 pulse widths according to an embodiment of the present application.

Fig. 6 is a timing diagram of parallel processing data according to an embodiment of the present application.

Fig. 7 is a flowchart illustrating steps of a laser ranging method according to an embodiment of the present disclosure.

Icon: 100-a laser ranging device; 10-a laser; 20-an emitting optical component; 21-a first mirror; 22-an optical device; 30-a receiving optical component; 40-a first photodetector; 50-a second photodetector; 60-a control module; 61-a master controller; 62-FPGA chip; 70-a servo motor; 80-a second mirror; 91-an operational amplifier circuit; 92-AD conversion circuit.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

Referring to fig. 1, an embodiment of the present application provides a laser ranging apparatus 100, including: a laser 10, a transmitting optical assembly 20, a receiving optical assembly 30, a first photodetector 40, a second photodetector 50, and a control module 60.

The laser 10 is used to emit laser light for scanning to a target object. The emitting optical assembly 20 is disposed in a light emitting direction of the laser light emitted from the laser 10, and the emitting optical assembly 20 is used to adjust the direction of the laser light. The receive optics assembly 30 is positioned in the echo path of the laser light reflected back through the target. The first photo detector 40 is electrically connected to the laser 10 and the control module 60, respectively, and in the embodiment of the present application, when the laser 10 emits a laser beam to a target object for scanning, the same seed light as the laser emitted by the laser 10 is transmitted to the first photo detector 40 at the same time. The seed light and the laser emitted by the laser 10 are the same, including the same waveform, pulse width and frequency. Wherein the first photodetector 40 is connected to the laser 10 by an optical fiber. The first photodetector 40 is configured to receive the seed light transmitted by the laser 10 and output a first electrical signal to the control module 60 based on the seed light. That is, the first photodetector 40 is configured to convert the optical signal of the received seed light into an electrical signal and output the electrical signal. The second photodetector 50 is disposed on the light-gathering path of the receiving optical assembly 30, and the second photodetector 50 is also electrically connected to the control module 60, and the second photodetector 50 is configured to receive the echo gathered by the receiving optical assembly 30 and output a second electrical signal to the control module 60 based on the echo. That is, the second photodetector 50 is configured to convert the received optical signal of the echo into an electrical signal and output the electrical signal. The control module 60 is used to trigger the laser 10 (e.g., trigger the laser 10 to turn on or off, and the output power of the laser 10), and obtain the distance to the target object based on the first electrical signal output by the first photodetector 40 and the second electrical signal output by the second photodetector 50.

In the embodiment of the present application, when the laser 10 emits the laser light to the target object, the same seed light as the laser light emitted by the laser 10 is transmitted to the first photodetector 40 at the same time. The first photodetector 40 converts the optical signal of the seed light into a first electrical signal and outputs the first electrical signal to the control module 60, and the second photodetector 50 converts the received optical signal of the echo returned by the target into a second electrical signal and outputs the second electrical signal to the control module 60. Thereby enabling the control module 60 to obtain the accurate distance to the target object based on the first electrical signal and the second electrical signal. Compared with the prior art, the time of laser output can be accurately determined through the seed light which is the same as the laser at the same moment, and further the distance measurement precision is higher.

Referring to fig. 2, optionally, the emission optical assembly 20 includes a first mirror 21. The angle of the first reflector 21 is adjustable, and the first reflector 21 is arranged in the light emitting direction of the laser. The light emitting direction of the laser can be flexibly adjusted through the first reflector 21, and the flexibility of the distance measurement of the laser distance measuring device 100 is improved.

In order to facilitate the adjustment of the angle of the first reflecting mirror 21, the laser ranging apparatus 100 may optionally further include a servo motor 70. The servo motor 70 is electrically connected to the control module 60, and the servo motor 70 is connected to the first reflecting mirror 21. The servo motor 70 is used for receiving the rotation command sent by the control module 60, and further controlling the first reflecting mirror 21 to rotate. Such as controlling the first mirror 21 to rotate 360 degrees.

Of course, in other embodiments, the first reflecting mirror 21 may be manually adjusted in angle, and the present application is not limited thereto.

Optionally, in order to be able to increase the beam range of the received echo, the laser ranging device 100 comprises a second mirror 80. The second reflector 80 is arranged between the laser 10 and the first reflector 21, a through hole is arranged at the center of the second reflector 80, the laser emitted by the laser 10 is emitted into the first reflector 21 through the through hole, and then is emitted into the target object through the first reflector 21; the echo reflected by the object is incident on the receiving optical element 30 via the first mirror 21 and the second mirror 80. As can be seen from fig. 2, the receiving optical assembly 30 can receive a large area of the echo beam reflected by the second mirror 80. If the second reflecting mirror 80 is not provided, and the receiving optical assembly 30 can only be arranged on a certain side of the laser at this time, the beam range of the received echo is necessarily smaller, and therefore, with the structure provided by the embodiment of the present application, that is, by arranging the second reflecting mirror 80 between the laser 10 and the first reflecting mirror 21, the beam range of the received echo can be increased.

Optionally, the emitting optical assembly 20 further includes an optical device 22 such as a lens barrel, a grating, etc. The optics 22 described above are connected to the laser 10. Accordingly, as an embodiment, the second mirror 80 may be disposed between the optical device 22 and the first mirror 21 (as shown in fig. 2), and as another embodiment, the second mirror 80 may be disposed outside the optical device 22, that is, the optical device 22 passes through a through hole in the second mirror 80 (as shown in fig. 3). The specific installation position of the second reflector 80 is not limited in the present application.

Alternatively, the receiving optical assembly 30 may be a focusing lens, an imaging lens, or the like, and the present application is not limited thereto.

Optionally, the laser 10 is a pulsed laser. Of course, in other embodiments, the laser may also be a solid laser, a semiconductor laser, etc., and the present application is not limited thereto.

Referring to fig. 4, in the embodiment of the present application, the control module 60 includes: a main controller 61 and an FPGA (field programmable Gate Array) chip 62. The main controller 61 is electrically connected to the FPGA chip 62.

The main controller 61 is electrically connected to the laser 10, and the main controller 61 is used for triggering the laser 10 (for example, triggering the laser 10 to be turned on or off, and triggering the output power of the laser 10).

Optionally, when the laser 10 is a pulsed laser, the main controller 61 is also configured to trigger the pulsed laser to emit a waveform with a different pulse width for each preset time interval.

It should be explained that, in the conventional laser radar ranging, a laser transmits a laser waveform with equal pulse width, and meanwhile, a signal which is also a pulse is received by a collecting end, so that the next laser must be emitted after receiving an echo signal returned by the previous laser from a target object, otherwise, the echo cannot be distinguished from the echo of which laser number. In a specific application scenario, for example, in the detection of a catenary, it is generally considered that a laser pulse scans one circle to one line; the more effective points in a line, the higher the identification precision of the detected contact network.

Assuming an effective ranging range of 15 meters; then the minimum time interval t of laser ranging is 2 × 15/c is 100 nanoseconds; where c is the speed at which light propagates in air. I.e. the maximum measurement frequency is P (equal to 10M); meanwhile, the pulse scanning frequency of the laser is assumed to be N circles/second; the effective pulse number of the single line is M (equal to P/N). Under the condition that the rotating speed R of the scanner is fixed, the higher the laser repetition frequency is, the more effective ranging pulse data of a single line is. The trigger frequency of the laser is improved, and the effective pulse data of a single line can be increased; therefore, longer railway mileage can be detected in a limited time, and the detection efficiency is greatly improved. Therefore, in order to increase the frequency of measurement, it is adopted that by emitting laser waveforms of different pulse widths, each seed light and its corresponding echo signal can be distinguished by its pulse width (as shown in fig. 5, fig. 5 shows waveforms of different pulse widths in fig. 4). Of course, in other embodiments, the preset time interval may be 150 ns, 200 ns, etc. besides 100 ns, which is not limited in this application.

The FPGA chip 62 is electrically connected to the first photodetector 40 and the second photodetector 50, respectively, and the FPGA chip 62 is configured to process a first electrical signal output by the first photodetector 40 in parallel and process a second electrical signal output by the second photodetector 50 in parallel. Specifically, the FPGA chip 62 is configured to process waveform data in a first electrical signal output by the first photodetector 40 in parallel, and process waveform data in a second electrical signal output by the second photodetector 50 in parallel. The FPGA chip 62 is also configured to obtain a distance to the target object based on the first electrical signal and the second electrical signal.

In general, the waveform data rate can reach 5GHz × 10bit, so that the subsequent processing of the waveform data by the FPGA chip 62 also meets the rate of 5GHz × 10bit to meet the real-time requirement. In order to ensure the running stability of the FPGA program, for example, a clock of 208.3MHz is selected as an operating clock for data processing, so that 24 data needs to be processed simultaneously in each clock cycle, that is, 5GHz × 10bit is converted into 208.3MHz × 240 bit. If 24 data are judged simultaneously, because waveform identification needs to be combined with one section of data for judgment, rather than independent judgment of single data, the judgment conditions among the 24 data are coupled, so that the internal connection path of the FPGA after synthesis is too long to complete in one period, and the timing sequence requirement is not met. Therefore, the characteristics of the parallelism of the FPGA can be utilized, 4 parallel modules are adopted to process data, namely each module simultaneously processes 6 waveform data in one clock period. As an embodiment, the 4 parallel modules may not process 24 data of the same clock cycle, but store 5GHz data of a period of time into a memory, and a single module sequentially takes out 6 data at a clock frequency of 208.3MHz and processes the data, and switches to access of another memory at a next laser trigger signal, so as to implement real-time waveform processing on the 5GHz data, as shown in fig. 6, when module 1 processes data stream 1, module 2 processes data stream 2 next, module 3 processes data stream 3 again, module 4 processes data stream 4 again, and then circulates, and module 1 receives processed data stream 5 again, and implements parallel processing of the FPGA chip. Of course, in other embodiments, the clock frequency may also be 200MHz, and the application is not limited thereto.

In the embodiment of the present application, the FPGA chip 62 may process the first electrical signal output by the first photodetector 40, process the second electrical signal output by the second photodetector 50, and obtain the distance to the target object based on the first electrical signal and the second electrical signal. By parallel processing of the data, the processing time can be reduced.

It should be noted that, a specific ranging algorithm of the FPGA chip 62 is explained in the following method embodiment, and at this time, too much description is not made.

With reference to fig. 4, the laser distance measuring device may further include an operational amplifier circuit 91. The operational amplifier circuit 91 is electrically connected to the first photodetector 40, the second photodetector 50, and the control module 60, respectively. The operational amplifier circuit 91 is configured to process weak electrical signals transmitted by the first photodetector 40 and the second photodetector 50, and includes a transimpedance operational amplifier and an automatic gain operational amplifier. It should be noted that since the transimpedance operational amplifier and the automatic gain operational amplifier are well known in the art, the present application does not make much explanation.

When the control module 60 includes the main controller 61 and the FPGA chip 62, the operational amplifier circuit 91 is electrically connected to the FPGA chip 62.

Optionally, the laser ranging apparatus 100 further includes an AD conversion circuit 92. The AD conversion circuit 92 is electrically connected to the first photodetector 40, the second photodetector 50, and the control module 60, respectively. The AD conversion circuit 92 is configured to convert an analog signal output by the first photodetector 40 into a digital signal, and convert an analog signal output by the second photodetector 50 into a digital signal, and further output the digital signal to the control module 60. Since the AD conversion circuit 92 has a circuit configuration well known in the art, the description thereof will not be made in an excessive manner.

When the control module 60 includes the main controller 61 and the FPGA chip 62, and the laser ranging device 100 includes the operational amplifier circuit 91, the AD conversion circuit 92 is electrically connected to the operational amplifier circuit 91 and the FPGA chip 62, respectively.

Optionally, the laser distance measuring device 100 further includes a display module. The display module is connected to the control module, wherein the display module can be electrically connected to the control module 60. When the laser ranging device 100 further includes a communication module, the control module 60 may also establish a communication connection with the display module. The display module is used for displaying the distance of the target object acquired by the control module.

The display module may be a display, a tablet, or a mobile phone, that is, the display module may also be any terminal device including a display interface.

Based on the same conception, the embodiment of the application also provides a contact net detection device. The laser ranging device comprises a vehicle body and the laser ranging device arranged on the vehicle body and provided with the embodiment. When the train body moves on a railway, the laser ranging device arranged on the train body can measure the distance of the contact net. The laser ranging device provided by the embodiment of the application can improve the accuracy of the detected distance.

It can be understood that the laser ranging device provided by the embodiment of the application can be applied to the aerospace field except being applied to the detection field of a contact network, for example, is arranged on an unmanned aerial vehicle and is used for monitoring the flying environment.

Referring to fig. 7, based on the same concept, an embodiment of the present application further provides a laser ranging method applied to a control module in the laser ranging apparatus according to the above embodiment, where a laser in the laser ranging apparatus is a pulse laser, and the method includes: step S101-step S103.

Step S101: receiving a first electrical signal output by the first photodetector and receiving a second electrical signal output by the second photodetector.

Step S102: performing Gaussian fitting on the seed optical waveform corresponding to the first electrical signal and performing Gaussian fitting on the echo waveform corresponding to the second electrical signal; and acquiring the central position of the fitted seed optical waveform and the central position of the fitted echo waveform.

The following is a description of a specific procedure of the above-described gaussian fitting.

The gaussian waveform can be represented by the following formula (1):

wherein y is the amplitude, x is the abscissa value, S, A is the gaussian form factor, and μ is the abscissa of the center point.

Taking logarithm from two sides of the formula at the same time to obtain:

let In y be z;

obtaining:

z＝b₀+b₁x+b₂x²(3)

the n waveform data are written in a matrix form, it should be noted that the subsequent calculation process is to process the seed optical waveform and the echo waveform respectively, and the processing processes are the same, so the n waveforms in this step may refer to the seed optical waveform or the echo waveform. The matrix form is as follows:

is recorded as:

Z＝XB (6)

the least square principle is utilized to obtain:

(X^TXB)＝X^TZ (7)

B＝(X^TX)^-1X^TZ (8)

expanding the formula (7) into a matrix form:

due to the X in the above formula^TX and X^TZ is a known number, and when the equation is solved by using the gaussian elimination method directly, multiple division operations are introduced, one division operation takes several to ten clock cycles, and the integer division loses precision, so optimization is required. Note that x is the continuous abscissa of the waveform, noting the initial x₁After the coordinates of (2), can let x_iI, i.e. (9) is formulated as:

using the summation formula:

substituting the summation formula (11) into the summation formula (10) to obtain:

the equation (12) is simplified by using a Gaussian elimination method to obtain:

the central point mu of the seed light waveform can be obtained by the formula (13)₁And the center point mu of the echo waveform₂Due to the starting point x of the seed light waveform₁And the starting point x of the echo waveform₂It is known, therefore, that the center point μ of the seed light waveform can be based on₁And the starting point x of the seed light waveform₁Obtaining the accurate central position of the seed light waveform and the central point mu based on the echo waveform₂And the starting point x of the echo waveform₂And acquiring the accurate central position of the echo waveform.

Step S103: and acquiring the distance of the target object based on the center position of the fitted seed light waveform and the center position of the fitted echo waveform.

Obtaining the central point mu of the seed light waveform through the above₁And the center point mu of the echo waveform₂Then, based on the center point mu of the seed light waveform₁And the starting point x of the seed light waveform₁Obtaining the accurate central position of the seed light waveform and the central point mu based on the echo waveform₂And the starting point x of the echo waveform₂Acquiring the accurate central position of the echo waveform, and further acquiring a distance value d of a target object:

c is the speed of light traveling in air.

Optionally, if the control module triggers the laser to emit waveforms with different pulse widths within a preset time interval, the receiving the first electrical signal output by the first photodetector and the receiving the second electrical signal output by the second photodetector in step S101 further includes:

receiving a plurality of first electrical signals output by the first photodetector and receiving a plurality of second electrical signals output by the second photodetector.

Correspondingly, step S102, performing gaussian fitting on the seed optical waveform corresponding to the first electrical signal and performing gaussian fitting on the echo waveform corresponding to the second electrical signal includes: acquiring a target seed optical waveform and a target echo waveform which have the same waveform in a seed optical waveform corresponding to the first electric signal and an echo waveform corresponding to the second electric signal; and performing Gaussian fitting on the target seed light waveform and the target echo waveform.

Correspondingly, in step S103, obtaining the distance to the target object based on the center position of the fitted seed optical waveform and the center position of the fitted echo waveform, includes: and acquiring the distance of the target object based on the center position of the fitted target seed optical waveform and the center position of the fitted target echo waveform.

It can be understood that the embodiment of the present application provides a continuous multi-pulse distance measurement method, in which the control module triggers the laser to emit waveforms with different pulse widths within a preset time interval, and then the waveforms with the same pulse width are processed, that is, each seed light and its corresponding echo signal can be distinguished by its pulse width. By the mode, continuous pulse trigger measurement is realized, and the next laser beam is not required to be emitted after the echo signal returned from the target object by the previous laser is received.

Optionally, before performing gaussian fitting on the seed light waveform corresponding to the first electrical signal and performing gaussian fitting on the echo waveform corresponding to the second electrical signal, the method further includes: acquiring a maximum value m of a waveform in the first electric signal and a maximum value n of a waveform in the second electric signal; and filtering the waveform of which the peak value is smaller than m/2 in the first electric signal to obtain the seed optical waveform, and filtering the waveform of which the peak value is smaller than n/2 in the second electric signal to obtain the echo waveform.

That is, the present application adopts a threshold filtering method that performs filtering with half of the maximum value of the acquired waveform as a threshold. Thereby removing interference waveforms smaller than the threshold. In the prior art, the flexibility of a fixed threshold method is poor, if the threshold is too low, data of waveform bottom deformation and low signal-to-noise ratio can be intercepted, the fitting precision and the ranging precision are influenced, and if the threshold is too high, small signal echoes can be ignored, and the ranging range is influenced. Therefore, the filtering method using the half-wave height as the threshold value provided by the application has better flexibility and accuracy.

Of course, in other embodiments, filtering may also be performed according to dimensions such as width and intensity of the waveform, which is not limited in this application.

In summary, the laser ranging method provided by the embodiment of the present application corrects the seed light waveform and the echo waveform through the gaussian waveform fitting algorithm, so that the distance value of the target object obtained through the seed light waveform and the echo waveform is more accurate. In addition, the method can also carry out continuous pulse trigger measurement without waiting for the next laser beam to be emitted after the echo signal returned by the last laser from the target object is received. In addition, the embodiment of the application also performs filtering by taking the half-wave height as a threshold value, so that the overall flexibility and the filtering accuracy are provided.

In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A laser ranging device, comprising:

a laser; for emitting laser light and transmitting the same seed light as the laser light while emitting the laser light;

the emission optical assembly is arranged in the light emitting direction of the laser; the emission optical component is used for adjusting the direction of the laser;

the receiving optical assembly is arranged on an echo path of the laser reflected by the target object;

a first photodetector connected to the laser for receiving the seed light and outputting a first electrical signal based on the seed light;

the second photoelectric detector is arranged on a light condensation path of the receiving optical assembly and used for receiving the echo after being condensed by the receiving optical assembly and outputting a second electric signal based on the echo; and

the control module is respectively electrically connected with the laser, the first photoelectric detector and the second photoelectric detector, and is used for triggering the laser and acquiring the distance of the target object based on the first electric signal and the second electric signal.

2. The laser ranging device as claimed in claim 1, wherein the control module comprises: the device comprises a main controller and an FPGA chip; the main controller is electrically connected with the FPGA chip;

the main controller is electrically connected with the laser, and is used for triggering the laser;

the FPGA chip is electrically connected with the first photoelectric detector and the second photoelectric detector respectively, and is used for processing the first electric signal in parallel, processing the second electric signal in parallel and acquiring the distance of the target object based on the first electric signal and the second electric signal.

3. The laser ranging device as claimed in claim 1, wherein the emission optical assembly comprises: the angle of the first reflector is adjustable, and the first reflector is arranged in the light emitting direction of the laser.

4. The laser ranging device as claimed in claim 3, further comprising a servo motor electrically connected to the control module, wherein the servo motor is connected to the first reflecting mirror, and the servo motor is configured to receive a rotation command sent by the control module, so as to control the first reflecting mirror to rotate.

5. The laser rangefinder according to claim 3, characterized in that the laser rangefinder comprises a second mirror disposed between the laser and the first mirror, and a through hole is disposed at the center of the second mirror, and the laser emitted by the laser is incident on the mirror through the through hole and then incident on the target; the echo reflected by the object is reflected by the first mirror and the second mirror into the receiving optical assembly.

6. The laser ranging device as claimed in claim 1, wherein the laser is a pulsed laser.

7. The laser ranging device as claimed in claim 6, wherein the control module is further configured to trigger the laser to emit a waveform with different pulse widths in each preset time interval.

8. A laser ranging method applied to a control module in the laser ranging device according to claim 1, wherein the laser is a pulse laser, and the method comprises the following steps:

receiving a first electrical signal output by the first photodetector and receiving a second electrical signal output by the second photodetector;

performing Gaussian fitting on the seed optical waveform corresponding to the first electrical signal and performing Gaussian fitting on the echo waveform corresponding to the second electrical signal; acquiring the center position of the fitted seed optical waveform and the center position of the fitted echo waveform;

and acquiring the distance of the target object based on the center position of the fitted seed light waveform and the center position of the fitted echo waveform.

9. The laser ranging method of claim 8, wherein the receiving a first electrical signal output by the first photodetector and receiving a second electrical signal output by the second photodetector comprises:

receiving a plurality of first electrical signals output by the first photodetector and receiving a plurality of second electrical signals output by the second photodetector;

correspondingly, performing gaussian fitting on the seed optical waveform corresponding to the first electrical signal and performing gaussian fitting on the echo waveform corresponding to the second electrical signal includes:

acquiring a target seed optical waveform and a target echo waveform which have the same waveform in a seed optical waveform corresponding to the first electric signal and an echo waveform corresponding to the second electric signal;

performing Gaussian fitting on the target seed light waveform and the target echo waveform;

correspondingly, obtaining the distance of the target object based on the center position of the fitted seed light waveform and the center position of the fitted echo waveform includes:

and acquiring the distance of the target object based on the center position of the fitted target seed optical waveform and the center position of the fitted target echo waveform.

10. The laser ranging method of claim 8, wherein prior to the gaussian fitting of the seed light waveform corresponding to the first electrical signal and the gaussian fitting of the echo waveform corresponding to the second electrical signal, the method further comprises:

acquiring a maximum value m of a waveform in the first electric signal and a maximum value n of a waveform in the second electric signal;

and filtering the waveform of which the peak value is smaller than m/2 in the first electric signal to obtain the seed optical waveform, and filtering the waveform of which the peak value is smaller than n/2 in the second electric signal to obtain the echo waveform.