AU2020103665A4 - Low-altitude Light Small Area Array LiDAR Measuring System - Google Patents
Low-altitude Light Small Area Array LiDAR Measuring System Download PDFInfo
- Publication number
- AU2020103665A4 AU2020103665A4 AU2020103665A AU2020103665A AU2020103665A4 AU 2020103665 A4 AU2020103665 A4 AU 2020103665A4 AU 2020103665 A AU2020103665 A AU 2020103665A AU 2020103665 A AU2020103665 A AU 2020103665A AU 2020103665 A4 AU2020103665 A4 AU 2020103665A4
- Authority
- AU
- Australia
- Prior art keywords
- laser
- module
- measuring
- lens
- measuring system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
Classifications
-
- 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
- G01S17/42—Simultaneous measurement of distance and other co-ordinates
-
- 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
- G01S17/86—Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
-
- 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
- G01S17/88—Lidar systems specially adapted for specific applications
- G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
- G01S17/894—3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
-
- 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
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/53—Determining attitude
-
- 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
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
-
- 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
- G01S7/483—Details of pulse systems
- G01S7/486—Receivers
- G01S7/4861—Circuits for detection, sampling, integration or read-out
- G01S7/4863—Detector arrays, e.g. charge-transfer gates
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C11/00—Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
- G01C11/02—Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures
- G01C11/025—Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures by scanning the object
-
- 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
- G01S17/88—Lidar systems specially adapted for specific applications
- G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/1066—Beam splitting or combining systems for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view
Abstract
The invention discloses a low-altitude light small area array LiDAR measuring system. A
main control subsystem of the measuring system triggers a pulse laser emitting module to emit
laser, and the laser emitting module generates two paths of laser signals through a beam splitter
after being collimated, wherein one path of laser signals is used for determining laser emitting
time and generating a timing start signal, the other path of laser signals irradiates a target
through beam expansion, an echo signal is received by an avalanche photo diode (APD) array
detection module and generates a N2 path stop pulse, and a multi-channel high-precision time
interval measuring module is combined with the start signal to measure the N2 path laser round
trip flight time difference of a rectangular detection area. The position attitude measuring
subsystem, the main control subsystem and the area array LiDAR ranging subsystem of the
measuring system are integrated into a whole, the original 3D information can be obtained in
real time, and assembly and calibration are avoided. The LiDAR measuring system can perform
3D imaging without scanning and with single pulse, has the advantages of high imaging speed,
high measuring precision and working efficiency, small volume and light weight, and is
suitable for carrying a low-altitude light and small remote sensing platform.
1/2
FIGURES
(North
-kI
ZI
Flight
Direction -------
S(North)
Height ... Laser divergence angle (35mrad)
Y
Single Pulse illunination area diameter e
X
Figure I
Description
1/2
-kI ZI (North
Flight Direction -------
S(North)
Height ... Laser divergence angle (35mrad)
Single Pulse illunination diameter area e
Figure I
Low-altitude Light Small Area Array LiDAR Measuring System
The invention relates to a LiDAR technology in the field of active optical aerial remote sensing load, in particular to an area array LiDAR measuring system suitable for being carried by a low-altitude light and small remote sensing platform.
LiDAR measuring is a kind of active optical remote sensing technology, which has been rapidly developed into a hot spot, provides an important means to obtain spatial three-dimensional (3D) data, and is suitable for target detection, earth observation, 3D modeling of urban buildings, and investigation and planning of traffic lines, power lines and oil and gas pipelines. The LiDAR measuring system comprises a laser ranging unit, a position and attitude measuring unit and a main control unit. The method comprises the following steps: measuring distance information by a laser ranging unit; and calculating accurate 3D coordinates of a detection target by combining the position and attitude information obtained by the laser ranging time position and attitude measuring unit, so as to realize 3D imaging. The three units are separated from each other in a conventional LiDAR measuring system, the three units are required to be assembled and disassembled each time of use, parameters are changed each time of disassembly, and if high-precision data are desired to be collected, the three units are required to be re-calibrated before use. This combination of discrete units not only affects the use efficiency, but also results in an increase in volume and weight of the whole LiDAR measuring system, making it difficult to reduce in weight and volume.
A laser ranging unit is the core of a LiDAR measuring system, a laser transmitter emits a beam of laser to irradiate a target object, a receiver converts an echo signal reflected by the target into an electric signal, and a LiDAR processor obtains a distance value from the measuring system to the target object. The traditional laser ranging unit adopts a mode of single-point transmission and single-point reception, has high requirement on laser repetition frequency, needs to be matched with a mechanical scanning device for imaging, has large volume and large power consumption, reduces the imaging speed and limits the application range of the laser ranging unit.
In order to overcome the shortcomings of scanning single-point detection, the area array LiDAR measuring system has begun to be studied internationally. At present, the intensified charge-coupled device (ICCD), which is an image-enhanced charge-coupled element area detector, is mainly used for 3D imaging. The Chinese Invention Patent Specification CN101498786A and the Journal of Optoelectronic Engineering, February 2013, Vol. 40, No. 2 "Staring Imaging LiDAR Based on Area Array Detectors" both disclose the research of ICCD area array detectors for non-scanning 3D imaging. However, there are some shortcomings in this method. First, the ICCD area detector cannot directly obtain the distance information, which needs to adopt the modulation and demodulation method, and at least two intensity images are used to calculate the distance image, which leads to a large amount of data processing and a high demand for processor processing and storage space; Second: due to the use of modulation and demodulation, a modulator with additional high-voltage modulation power must be used when receiving echo signals, and a demodulator for processing intensity images is required when generating 3D information. The additional devices make the LiDAR measuring system complicated to implement, and the volume and weight are still large; Third: the range measuring error obtained in the journal literature above is 0.6m, which cannot meet the low-altitude detection requirements for high range accuracy occasion.
an avalanche photodiode(APD) area array detector, is an NxN APD array detector integrated by a plurality of independent APD unit detectors, which has compact structure, small volume and light weight. Compared with an APD unit detector, scanning-free laser detection can be realized, and 3D imaging can be realized by single pulse; and compared with an ICCD detector, the APD array detector can directly obtain 3D information, so that the imaging speed is higher, and the system structure is simple.
Compared with a single-point laser ranging mode, the single-pulse laser emitted by the area array laser ranging mode needs to illuminate a larger target area, and the single-pulse laser is required to achieve extremely high peak power when the area array laser ranging mode is used for long-distance detection, so that the requirement on the research and development of the laser is high, and the volume, the weight and the cost of the laser are increased.
The invention aims to solve the problems of the prior LiDAR measuring system and provides a low-altitude light small area array LiDAR measuring system. The measuring system provided by the invention does not need scanning, single pulse can be used for 3D imaging, the imaging speed is high, the measuring precision and the working efficiency are high, the volume and the weight are obviously reduced, and the measuring system is suitable for carrying a low-altitude light and small remote sensing platform.
The low-altitude light small area array LiDAR measuring system is realized from the following four aspects: Firstly, an area array LiDAR distance measuring method based on an NxN APD (N >=8) array detector is provided, an APD area array detector that is recently developed in the world is adopted, a direct detection mode is adopted, a scanning device is not needed, single pulse can detect NxN points in a rectangular area, the system is compact in structure, high in imaging speed and high in detection efficiency. Secondly, a multi-channel high-precision time interval measuring module is developed by selecting a high-resolution timing chip, the time difference of N 2 paths of laser to-and-fro flight can be measured in parallel at each time, the distance information of NxN target measuring points on a detection area can be calculated according to a laser distance measuring formula, and the test shows that the distance measuring error is less than 0.12m. Thirdly, the LiDAR measuring system integrates the position attitude measuring subsystem, the main control subsystem and the area array LiDAR ranging subsystem into a whole, thereby reducing the volume of the measuring system, avoiding assembly before use and parameter re-calibration, and improving the use efficiency; and Fourthly, based on the low-altitude remote sensing application, the LiDAR measuring system can select the light small pulse laser with the peak power not very high as the light source, thereby further reducing the size and the weight of the LiDAR measuring system.
The invention relates to a low-altitude light small area array LiDAR measuring system, which comprises a position and attitude measuring subsystem, a main control subsystem and an area array LiDAR ranging subsystem.
The position and attitude measuring subsystem is composed of Global Positioning System (GPS) receiver and attitude measuring module.
The main control subsystem consists of a microcontroller, a timer and a memory.
The area array LiDAR distance measuring subsystem consists of a pulse laser emitting module, a collimating lens, a light splitting sheet, a total reflection mirror, a beam expanding emitting lens, a PIN high-speed photoelectric detection module, a receiving lens, a focal plane adjustable lens, a filter sheet, an APD array detection module and a multi-channel high-precision time interval measuring module.
The GPS receiver is used for providing a pulses per second (PPS), a pulse signal, as a starting signal of the measuring system and acquiring longitude, latitude, elevation and Coordinal Universal Time (UTC) of the measuring system, i. e. coordinated world time information; and the attitude measuring module is used for acquiring heading angle, pitch angle and side rolling angle information of the measuring system.
As the control center of the measuring system, the microcontroller starts the measuring system under the trigger of the PPS signal, controls the timer to time, reads the position information of the GPS receiver, controls the attitude measuring module to work and reads its attitude information, and triggers the pulse laser emission module emits laser, reads the time data of the multi-channel high-precision time interval measuring module and converts it into distance information, and saves these three kinds of information in the memory with the time synchronization tag; the memory is a lightweight and large-capacity memory, which is used to store the data collected by the measuring system; the timer starts timing when the microcontroller receives the PPS signal, and records the time difference between the GPS receiver positioning, the attitude measuring module, and the pulse laser emission module emitting laser. As the three time synchronization tags, the data collected by them are unified to UTC time based on the UTC time provided by GPS, so as to achieve the purpose of synchronization.
The pulse laser emission module has the characteristics of high power, narrow pulse, and adjustable output frequency. As the emission light source of this measuring system, the working wavelength of the pulse laser needs to be matched with the filter and the APD array detection module; the collimating lens and the beam expanding lens form the emitting optical system, and the receiving lens, the focal plane adjustable lens and the filter form the receiving optical system. The emitting optical system and the receiving optical system adopt a transmissive telescope method with a light transmitting/receiving parallel optical path structure; the emitting optical system is used for collimating the laser beam emitted by the pulse laser emission module, expanding the laser beam and irradiating the laser beam to the target. The divergence angle of the laser after collimation is determined according to the detection distance to meet the requirements of the target area required for one detection; the beam splitter and the total reflection mirror constitute a beam splitter for dividing the collimated laser into two lasers with a large splitting ratio; The PIN high-speed photoelectric detection module detects the smaller laser beam split by the beam splitter, which serves as the mark of laser emission time and the start signal of the multi-channel high-precision time interval measuring module; the receiving lens in the receiving optical system is used to receive the laser reflected by the target and focus on the focal plane adjustable lens, which needs to meet the requirements of the APD array detection module to receive the field of view. The focal plane adjustable lens is used to adjust the position and size of the laser focal plane after the receiving lens converges to ensure that the echo signal covers the entire photosensitive surface, and cooperate with the receiving lens to meet the requirements of optical power density and receiving field of view. The filter is used to filter out laser outside the working wavelength and suppress the interference of background light; the APD array detection module is NxN (N ' 8) array avalanche photoelectric detection module, the echo signal generates N 2 stop signal after photodetection and signal processing, the avalanche voltage is provided by low voltage DC power supply through boost, bias voltage and comparator reference level are adjustable, the output impedance and multi-channel high-precision time interval measuring module meets impedance matching; the multi-channel high-precision time interval measuring module is used to measure the N 2 time interval of the laser round-trip flight, and then the distance information of the N 2 targets representing a rectangular area is calculated according to the laser ranging formula, the number of channels of the multi-channel high-precision time interval measuring module is greater than or equal to the number of units of the APD array. In order to obtain high-precision distance information, each channel needs to meet high-precision timing requirements.
The working steps of the low-altitude light small area array LiDAR measuring system are as follows:
(1) When the microcontroller receives the PPS signal generated by the GPS receiver, the microcontroller triggers a timer to start timing.
(2) The microcontroller reads the position information and the UTC time information of the GPS receiver and stores the position information and the UTC time information in the memory, then controls the attitude measuring module to work, reads the attitude information output by the attitude measuring module and adds a time synchronization label to store the attitude information in the memory.
(3) The microcontroller controls the peripheral drive circuit to output the TTL level, triggers the pulse laser emission module to emit laser, the emitted laser is collimated by the collimating lens and then passes through the beam splitter to produce two laser signals, and a small part of the reflected laser passes through the total reflection mirror enters the PIN high-speed photoelectric detection module to generate the start signal and the laser emission time monitoring signal, and respectively input the START end of the multi-channel high-precision time interval measuring module and the interrupt port of the microcontroller, and most of the transmitted laser is irradiated target by the beam expanding emitting lens, the laser reflected by the target is focused on the focal plane adjustable lens through the receiving lens, and then converged to the APD array detection module by the filter to generate N 2 stop signals, which are respectively input to the N2 STOP terminals of the multi-channel high-precision time interval measuring module. The N 2 channels of time data obtained by multi-channel high-precision timing are transmitted to the microcontroller through the serial port, and then converted into N 2 distance values representing a rectangular area by the laser ranging formula, and saved in the memory after adding the time synchronization tag.
(4) Repeating the steps (2) and (3) until the original 3D information of the whole imaging area is obtained.
(5) Data post-processing is performed on the landing ground of the remote sensing platform to generate an accurate 3D image.
Compared with the prior art, the invention mainly has the following advantages:
1) a multi-channel high-precision time interval measuring module is developed by selecting a high-resolution timing chip, N 2 laser round-trip flight time difference can be measured in parallel every time, and the distance error of a target detection area is about 0.12m can be obtained;
2) compared with a single-point scanning LiDAR, the invention realizes non-scanning laser detection, can generate a 3D image by single laser pulse, has high imaging efficiency and low requirement on laser repetition frequency; and compared with an ICCD area array detection LiDAR, the invention does not need modulation and demodulation, simplifies the system structure, can quickly and directly acquire 3D information, and meets the carrying requirement of a light and small remote sensing platform.
3) the position attitude measuring subsystem, the main control subsystem and the area array LiDAR distance measuring subsystem are integrated into a whole, original 3D information can be acquired in real time on a remote sensing platform, and assembly and parameter re-calibration of each subsystem are avoided during use.
4) based on the low-altitude remote sensing application, the light and small pulse laser with the peak power not very high can be selected as the light source, so that the size and the weight of the LiDAR measuring system are further reduced; in addition, the low-altitude operation is less affected by climatic conditions, the airspace is more convenient to apply, therefore, the invention can be put into use more quickly.
Figure 1 is a working schematic diagram of a LiDAR measuring system mounted on an unmanned aerial vehicle according to the present invention.
Figure 2 is a block diagram of the structure and principle of the present invention.
In the figure, reference numerals: 1-position attitude measuring subsystem; 101-GPS receiver; 102-attitude measuring module.
2-main control subsystem; 201-microcontroller; 202-timer; 203-memory.
3-area array LiDAR ranging subsystem; 301-pulse laser emitting module; 302-collimating lens; 303-beam splitter; 304-total reflection mirror; 305- lens of beam expanding emitting; 306-PIN high-speed photoelectric detection module; 307-receiving lens; 308-focal plane adjustable lens; 309-filter; 310-APD array detection module; and 311-multi-channel high-precision time interval measuring module.
The present invention will now be further described with reference to the accompanying drawings and specific embodiments.
Embodiments:
As shown in the working schematic diagram of Figure 1, the LiDAR measuring system of the embodiment is mounted on a 200m low-altitude small unmanned aerial vehicle for 3D data acquisition work, a target area of 5mx5m can be detected by emitting a single laser pulse, the distance error of generated 3D image is less than 0.12m, and the pixel spacing is 0.625m.
As shown in Figure 2, the low-altitude light small area array LiDAR measuring system comprises a position and attitude measuring subsystem 1, a main control subsystem 2 and an area array LiDAR ranging subsystem 3.
The position attitude measuring subsystem 1 is composed of a GPS receiver 101 and an attitude measuring module 102.
The main control subsystem 2 consists of a microcontroller 201, a timer 202 and a memory 203.
The area array LiDAR ranging subsystem 3 consists of a pulse laser emitting module 301, a collimating lens 302, a beam splitter 303, a total reflection mirror 304, a beam expanding emitting lens 305, a PIN high-speed photoelectric detection module 306, a receiving lens 307, a focal plane adjustable lens 308, a filter 309, an APD array detection module 310 and a multi-channel high-precision time interval measuring module 311.
The collimating lens 302 and the beam expanding emitting lens 305 form an emitting optical system, the receiving lens 307, the focal plane adjustable lens 308 and the filter 309 form a receiving optical system, and the emitting optical system and the receiving optical system adopt a transmission type telescope mode with a light emitting/receiving parallel optical path structure.
The GPS receiver 101 is used for providing a PPS signal, UTC time information and position information of the measuring system, adopts a differential GPS receiver of OEMV-2 type from a NovAtel company of Canada, and has a horizontal position precision of 0.45 m, an update frequency of 50 Hz, and uses an RS232 serial interface to communicate with the microcontroller 201.
The attitude measuring module 102 is used for acquiring the attitude information of the measuring system, adopts an inertial measuring unit Inertial Measurement Unit (IMU), namely the inertial measuring unit, the data updating frequency can reach 100Hz, ensures that the acquired three attitude angle errors are less than 0.08 degree under the assistance of a GPS receiver, and uses an RS232 serial interface to communicate with the microcontroller 201.
The microcontroller 201 is a 32-bit ARM core microcontroller, is used as a control center of the measuring system, adopts an STM32 high-phenotype low-power consumption product of STMicroelectronics Company. Its clock frequency is up to 12OMHz.It include two Universal Serial BUS (USB), 15 the communication interfaces, 17 the 16-bit and 32-bit timers, the 1MHz capacity of the flash memory provided by the microcontroller 201, and can easily expand the storage capacity.
The timer 202 starts timing after the microcontroller receives the PPS signal of the GPS receiver 101, records the working time difference of the GPS receiver 101, the attitude measuring module 102 and the pulse laser emission module 301, unifies the time collected by the three to the UTC time so as to achieve the purpose of synchronization, and adopts the 32-bit timer provided by the microcontroller 201.
The memory 203 is a light mass memory for storing data collected by the measuring system. A Secure Digital Memory Card (SD card) is used, which is only 1.5 g in weight, up to 32 GB in capacity, and up to 30 MB/s in access speed.
The pulse laser emitting module 301 is used as an emitting light source of the measuring system, and adopts a pulse microchip laser module with an output center wavelength of 905nm, a pulse width of 8ns, a peak power of 29kw and adjustable repetition frequency.
The transmission type emitting optical system is consisting of the collimating lens 302 and the beam expanding emission lens 305, is used for collimating the laser beam emitted by the pulse laser emission module, expanding the laser beam and irradiating the laser beam to a target, the collimated laser divergence angle is 35mrad, and the collimating lens 302 needs to be plated with a 905nm anti-reflection film in order to improve the emission efficiency.
The beam splitter 303 divides the collimated laser into two beams of laser having a ratio of reflected light to transmitted light of 1: 999.
The total reflection mirror 304 is configured to transmit a smaller path of laser separated by the light splitting sheet 303 to the PIN high-speed photoelectric detection module 306.
The PIN high-speed photoelectric detection module 306 is used for detecting the laser incident from the total reflection mirror 304, generating an electric pulse signal as a mark of the laser emission moment and a start signal of the multi-channel high-precision time interval measuring module 311, detecting the incident laser by adopting a GT106 high-speed PIN photodiode of the China Electronics Technology Group Corporation (CETC) 44 division, and generating the required electric pulse signal by the transimpedance amplifier circuit and the high-speed comparator circuit.
The receiving lens 307 is an aspherical lens with an aperture of 120mm and a focal length of 100mm, is used for receiving laser reflected by a target and focusing on the focal plane adjustable lens 308, and is plated with a 905nm anti-reflection film for improving the receiving efficiency.
The focal plane adjustable lens 308 is used for adjusting the position and the size of a laser focal plane converged by the receiving lens 307, ensuring that an echo signal covers the whole photosensitive surface, meeting the requirements of optical power density and receiving field angle, and plating a 905nm anti-reflection film on the focal plane adjustable lens 308 for improving the receiving efficiency.
The filter 309 is a 905nm filter with a bandwidth of+/-10 nm and a transmittance of more than %, and is used for filtering laser outside the working wavelength and suppressing the interference of background light.
The APD array detection module 310 is an avalanche photoelectric detection module of an NxN array working in a linear mode, receives echo signals in a field-of-view range, carries out photoelectric detection through an 8x8 APD array, and then one-plane photoelectric detection is realized by processing stop signals produced by 64 independent high-speed transimpedance operational amplifiers and comparator two-stage circuits to generate 64 paths of stop signals so as to realize. Using the 8x8 APD array of first sensor company is adopted, the response at 905nm is A/W, the avalanche voltage is 200V, the high voltage bias voltage is obtained by 5V power supply boosting, the bias voltage and comparator reference level are adjustable, and the output impedance is 50 Ohm.
The multi-channel high-precision time interval measuring module 311 has an input impedance of 50 ohms and is used for measuring multi-channel time difference of laser round-trip flight so as to acquire distance information of a target measuring point representing a rectangular area. By using 8-channel TDC-GPX chip with timing resolution 81 picoseconds from ACAM Company of Germany, under the control of ARM core micro control unit or Field-Programmable Gate Array (FPGA), which is a field programmable gate array (FPGA), 8-chip TDC-GPX chip is developed. The time interval of 64-channel stop signal relative to start signal output by APD array detection module 310 can be measured in parallel. The module communicates with microcontroller 201 through USB interface.
The measuring system comprises the following working steps:
(1) When the microcontroller receives the PPS signal generated by the GPS receiver 101, it triggers the timer 202 to start timing.
(2) The microcontroller 201 reads the position information and the UTC time information of the GPS receiver 101 and stores them in the memory 203, then controls the operation of the attitude measuring module 102, reads the attitude information outputted from the attitude measuring module 102, and stores them in the memory 203 with a time synchronization tag.
(3) The microcontroller 201 controls the peripheral drive circuit output TTL level trigger pulse laser emission module 301 to emit laser, the emitted laser is collimated by the collimating lens 302 and then generates two paths of laser signals through the light splitting sheet 303, a small part of reflected laser enters the PIN high-speed photoelectric detection module 306 through the total reflection mirror 304 to generate a start signal and a laser emission time monitoring signal and respectively input the start signal and the laser emission time monitoring signal into the START end of the multi-channel high-precision time interval measuring module 311 and the interrupt port of the microcontroller 201, most transmitted laser is expanded by the beam expanding emitting lens 305 to irradiate a target, the target reflected laser is focused to the focal plane adjustable lens 308 through the receiving lens 307, and converged to an APD array detection module 310 through the filter 309 to obtain 64-path stop signals and respectively input the stop signals into the 64 STOP end of the multi-channel high-precision time interval measuring module 311, the 64-path time data obtained by the multi-channel high-precision time interval measuring module is transferred to the microcontroller 201 through serial port. It is converted into a 64-path distance value by a laser ranging formula representing a 5m*5m square target area, and the 64-path distance value is stored in the memory 203 after being added with a time synchronization tag.
(4) Repeating the steps (2) and (3) until the original 3D information of the imaging area required by the task is acquired.
(5) Data post-processing is performed on the landing ground of the unmanned aerial vehicle to generate an accurate 3D image.
The above disclosure is only one embodiment of the present invention, but the present invention is not limited thereto, any variations made by those skilled in the art without departing from the principles of the present invention are to be considered as being within the scope of the present invention.
Claims (1)
1. The low-altitude light small area array LiDAR measuring system, characterized in that the low-altitude light small area array LiDAR measuring system comprises a position attitude measuring subsystem (1), a main control subsystem (2) and an area array LiDAR ranging subsystem (3);
The position and attitude measuring subsystem (1) consists of a global positioning system (GPS) receiver (101) and an attitude measuring module (102);
The main control subsystem (2) consists of a microcontroller (201), a timer (202) and a memory (203);
The area array LiDAR ranging subsystem (3) consists of a pulse laser emitting module (301), a collimating lens (302), a beam splitter (303), a total reflection mirror (304), a beam expanding emitting lens (305), a PIN high-speed photoelectric detection module (306), a receiving lens (307), a focal plane adjustable lens (308), a filter (309), an avalanche photodiode array (APD) detection module (310) and a multi-channel high-precision time interval measuring module (311);
The GPS receiver (101) is used for providing a PPS (second pulse signal) as a starting signal of the measuring system and acquiring longitude, latitude, elevation and universal coordination (UTC) time information of the measuring system; the attitude measuring module (102) is used for acquiring heading angle, pitch angle and side rolling angle information of the measuring system;
As the control center of the measuring system, the microcontroller (201) starts the measuring system under the trigger of the PPS signal, controls the timer (202) to time, reads the position information of the GPS receiver (101), and controls the work of the attitude measuring module (102) and read the posture information, triggers the pulse laser emission module (301) to emit laser, reads the time data of the multi-channel high-precision time interval measuring module (311) and then converts the time data into distance information, and stores in the memory 203 after being added with a time synchronization tag; the memory (203) is a lightweight and large-capacity memory, used to store the data collected by the measuring system; the timer (202) starts when the microcontroller (201) receives the PPS signal time, records the time difference of the three moments of GPS receiver (101) positioning, attitude measuring module (102) attitude measuring, and pulse laser emission module (301) emitting laser, and uses the time difference as a time synchronization tag for the three, using the provided UTC time by GPS receiver (101) as a benchmark to unify the collected data to UTC time, so as to achieve the purpose of synchronization;
A pulse laser emitting module (301) is used as an emitting light source of the measuring system, and the working wavelength of the pulse laser emitting module (301) needs to be matched with a filter plate and an APD array detection module (310); an emitting optical system is formed by a collimating lens (302) and a beam expanding emitting lens (305); a receiving optical system is formed by a receiving lens (307), a focal plane adjustable lens (308) and a filter plate (309); the emitting optical system and the receiving optical system adopt a transmission type telescope mode of a light emitting/receiving parallel optical path structure; the emitting optical system is used for collimating a laser beam emitted by the pulse laser emitting module (301) and irradiating a target after beam expanding; the divergence angle of the laser after collimation is determined according to the detection distance to meet the requirements of the target area required for one detection; the beam splitter (303) and the total reflection mirror (304) constitute a beam splitter for dividing the collimated laser into two lasers with a large splitting ratio; the PIN high-speed photoelectric detection module (306) detects the smaller laser beam split by the beam splitter (303), which serves as the mark of laser emission time and the start signal of the multi-channel high-precision time interval measuring module (311); the receiving lens (307) in the receiving optical system is used for receiving laser reflected by the target and focus on the focal plane adjustable lens (308), which needs to meet the requirements of the APD array detection module (310) to receive the field of view, wherein the focal plane adjustable lens (308) is used for adjusting the position and the size of a laser focal plane after the receiving lens (307) is converged, ensuring that an echo signal covers the whole photosensitive surface, matching the receiving lens (307) to meet the requirements of optical power density and the receiving view angle, the filter (309) is used for filtering the laser outside the working wavelength and suppressing the interference of background light; the APD array detection module (310) is NxN (N '-8) array avalanche photoelectric detection module, the echo signal generates N 2 stop signal after photodetection and signal processing, the avalanche voltage is provided by low voltage DC power supply through boost, the bias voltage and comparator reference level are adjustable, the output impedance and the multi-channel high-precision time interval measuring module (311) meets impedance matching; the multi-channel high-precision time interval measuring module (311) is used for measuring the N 2 path time interval of laser round-trip flight, calculating the distance information of N 2 target measuring points representing a rectangular area according to a laser ranging formula, wherein the number of channels of the multi-channel high-precision time interval measuring module (311) is greater than or equal to the number of units of the APD array, and each channel needs to meet the high-precision timing requirement in order to acquire the high-precision distance information;
The working steps of the low-altitude light small area array LiDAR measuring system are as follows:
(1) The microcontroller (201) triggers a timer (202) to start timing after receiving a PPS signal generated by a GPS receiver (101);
(2) The microcontroller (201) reads the position information and the UTC time information of the GPS receiver (101) and stores the position information and the UTC time information in the memory (203), then controls the operation of the attitude measuring module (102), reads the attitude information output by the attitude measuring module (102) and stores in the memory (203) after adding a time synchronization tag;
(3) The microcontroller (201) controls the peripheral drive circuit to output TTL level, triggers the pulsed laser emission module (301) to emit laser, and the emitted laser is collimated by the collimating lens (302) and then passed through the beam splitter (303) to produce two laser signals, a small part of the reflected laser enters the PIN high-speed photoelectric detection module (306) through the total mirror (304) to generate the start signal and the laser emission time monitoring signal, and respectively input the START end multi-channel high-precision time interval measuring module (311) and the interrupt port of the microcontroller (201), most of the transmitted laser illuminates the target through the expander emitting lens (305), and the laser reflected from the target is focused on the focal plane adjustable lens (308) through the receiving lens (307), and then converge to the APD array detection module (310) through the filter (309) to generate N 2 stop signals, which are respectively input to the N 2 STOP ends of the multi-channel high-precision time interval measuring module (311), and the N 2 time data obtained by multi-channel high-precision timing is transmitted to the microcontroller (201) through the serial port, and then converted into N 2 distance values representing a rectangular area by the laser ranging formula, and stored in the memory (203) after adding a time synchronization tag;
(4) Repeating the steps (2) and (3) until the original 3D information of the whole imaging area is obtained;
(5) Data post-processing is performed on the landing ground of the remote sensing platform to generate an accurate 3D image.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2020103665A AU2020103665A4 (en) | 2020-11-25 | 2020-11-25 | Low-altitude Light Small Area Array LiDAR Measuring System |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2020103665A AU2020103665A4 (en) | 2020-11-25 | 2020-11-25 | Low-altitude Light Small Area Array LiDAR Measuring System |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| AU2020103665A4 true AU2020103665A4 (en) | 2021-02-04 |
Family
ID=74236367
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2020103665A Ceased AU2020103665A4 (en) | 2020-11-25 | 2020-11-25 | Low-altitude Light Small Area Array LiDAR Measuring System |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU2020103665A4 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113050119A (en) * | 2021-03-18 | 2021-06-29 | 陕西周源光子科技有限公司 | Judgment method suitable for interference of optical flash three-dimensional imaging radar |
| CN113614564A (en) * | 2021-07-09 | 2021-11-05 | 华为技术有限公司 | Detection control method and device |
| CN114296094A (en) * | 2021-12-31 | 2022-04-08 | 探维科技(苏州)有限公司 | Radar detection method, device, system and medium |
| CN114577692A (en) * | 2022-04-21 | 2022-06-03 | 亿慧云智能科技（深圳）股份有限公司 | Intelligent negative ion concentration detection device and detection method |
| CN114994703A (en) * | 2022-08-04 | 2022-09-02 | 浙江航天润博测控技术有限公司 | System for detecting hidden target behind leaf cluster |
| WO2023132903A1 (en) * | 2022-01-07 | 2023-07-13 | Ouster, Inc. | Optical system for full frame flash solid-state lidar system |
-
2020
- 2020-11-25 AU AU2020103665A patent/AU2020103665A4/en not_active Ceased
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113050119A (en) * | 2021-03-18 | 2021-06-29 | 陕西周源光子科技有限公司 | Judgment method suitable for interference of optical flash three-dimensional imaging radar |
| CN113614564A (en) * | 2021-07-09 | 2021-11-05 | 华为技术有限公司 | Detection control method and device |
| CN114296094A (en) * | 2021-12-31 | 2022-04-08 | 探维科技(苏州)有限公司 | Radar detection method, device, system and medium |
| WO2023132903A1 (en) * | 2022-01-07 | 2023-07-13 | Ouster, Inc. | Optical system for full frame flash solid-state lidar system |
| CN114577692A (en) * | 2022-04-21 | 2022-06-03 | 亿慧云智能科技（深圳）股份有限公司 | Intelligent negative ion concentration detection device and detection method |
| CN114577692B (en) * | 2022-04-21 | 2023-03-24 | 亿慧云智能科技（深圳）股份有限公司 | Intelligent negative ion concentration detection device and detection method |
| CN114994703A (en) * | 2022-08-04 | 2022-09-02 | 浙江航天润博测控技术有限公司 | System for detecting hidden target behind leaf cluster |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AU2020103665A4 (en) | Low-altitude Light Small Area Array LiDAR Measuring System | |
| CN103412313B (en) | Small low-altitude light area array laser radar measuring system | |
| CN203385859U (en) | Area array laser radar measuring device | |
| CN109375237B (en) | A kind of all solid state face array three-dimensional imaging laser radar system | |
| CN103744087B (en) | A kind of pulse type N*N-array laser radar system | |
| AU2020103610A4 (en) | N*N Array LiDAR System | |
| CN1316262C (en) | Detection method and laser radar of Raman-Mie scattering laser atmospheric signal | |
| EP1962107B1 (en) | High-speed laser ranging system including a fiber laser | |
| CN1831559B (en) | Satellite laser range-measurement system based on tilt correction | |
| CN100394211C (en) | Multi-frequency synchronous modified large range high precision fast laser ranging method and apparatus | |
| CN110308456A (en) | It is a kind of for improving the bias adjustment device and laser radar system of detection range | |
| CN203688802U (en) | NxN array laser radar device | |
| CN106772315A (en) | Multi-beam scanning apparatus and multibeam scanning method | |
| CN108152830A (en) | A kind of laser radar scanning imaging system and its measuring method | |
| CN100478704C (en) | Chaos laser range-meaurement device and method of LD pumping solid laser | |
| CN206411262U (en) | Multi-beam scanning apparatus | |
| CN114167436B (en) | Single-frequency water measuring laser radar | |
| CN103344962B (en) | Laser pulse distance measurement method based on light path differences | |
| CN112219135A (en) | Distance measuring device, distance measuring method and mobile platform | |
| US20220120899A1 (en) | Ranging device and mobile platform | |
| CN108051796A (en) | A kind of miniaturization coaxial-type laser radar system based on TOF | |
| CN114428239A (en) | Laser radar, method for acquiring flight time of laser radar, method for measuring distance of laser radar, and storage medium | |
| CN207833020U (en) | A kind of laser radar scanning imaging system | |
| CN110687545B (en) | High-precision laser radar system | |
| CN116299510A (en) | MEMS-based frequency modulation continuous wave laser radar system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FGI | Letters patent sealed or granted (innovation patent) | ||
| MK22 | Patent ceased section 143a(d), or expired - non payment of renewal fee or expiry |