A multi-transmitter and single-receiver low-cost laser radar device

Abstract

The invention discloses a multi-transmitter and single-receiver low-cost laser radar device, comprising: a laser emitting unit, an optical path transceiver unit, a weak light detection unit, a digital camera and a laser radar host; the laser emitting unit is an all-in-one laser emitter, which combines the optical axes of lasers emitted by multiple lasers into the same optical axis, and then sends the emitted laser to the detection target through the optical path transceiver unit, and the echo signal returned by the detection target is sent to the weak light detection unit through the optical path transceiver unit; the digital camera is electrically connected to the laser radar host through a pin to realize time synchronization control, and the digital camera shoots the detection target and transmits the shooting data to the laser radar host. The invention is realized by multiple laser emissions and one weak light detection, and the object measurement rate is increased exponentially by increasing the scanning point density while ensuring that the detection distance remains unchanged, while ensuring low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of laser radar earth observation, and in particular to a multi-transmitter and single-receiver low-cost laser radar device. Background Art

[0002] The laser radar (LiDAR) system is an active detection system that integrates laser ranging, global positioning system, inertial navigation system technology and high-resolution digital imaging technology to quickly obtain high-resolution three-dimensional position information of the target. In recent years, airborne LiDAR technology has been used in the world as a technology for accurately and quickly obtaining three-dimensional surface information. The application scope of domestic drone-mounted laser radar has expanded to multiple civil and military fields. Laser radar has broad development prospects and application needs in many fields such as terrain monitoring, environmental monitoring, land surveying and mapping, emergency surveying and mapping, engineering survey, and three-dimensional smart city construction.

[0003] In actual projects, laser radar, especially the line inspection laser radar used for high-voltage transmission line inspection, has higher and higher requirements for the resolution (laser point cloud density) of the collected laser point cloud. The amount and accuracy of laser point cloud data per square meter must be greatly improved. Currently, there are two main technical methods to achieve this:

[0004] (1) This is achieved by using expensive high-repetition-rate, high-single-pulse-energy lasers. This method requires the use of fiber lasers or solid-state lasers. However, when operating in high-repetition-rate mode, the laser single-pulse energy or peak power decreases significantly, and the laser detection distance also decreases significantly.

[0005] (2) It is achieved by using multiple low-repetition-rate lasers and multiple corresponding weak-light detectors. This method requires leveling multiple corresponding transmitting and receiving optical paths during manufacturing, which not only reduces batch production efficiency but also increases the cost of weak-light echo detection materials. Summary of the invention

[0006] The technical problem to be solved by the present invention is: to provide a multi-transmitter and single-receiver low-cost laser radar device in response to the above-mentioned problems.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A multi-transmitter and single-receiver low-cost laser radar device comprises: a laser emitting unit, an optical path transceiver unit, a weak light detection unit, a digital camera and a laser radar host; the laser emitting unit is an all-in-one laser transmitter, which combines the optical axes of lasers emitted by multiple lasers into the same optical axis, and then sends the emitted laser to the detection target via the optical path transceiver unit, and the echo signal returned by the detection target is sent to the weak light detection unit via the optical path transceiver unit; the digital camera is electrically connected to the laser radar host via a pin, and is used to shoot the detection target and transmit the shooting data to the laser radar host; the laser radar host is used to receive and process the shooting data of the digital camera and to power the digital camera and perform time synchronization control.

[0009] Furthermore, the all-in-one laser transmitter comprises N lasers and a collimating beam expander; the optical axes of the lasers emitted by the N lasers are merged into one optical axis after passing through the collimating beam expander.

[0010] Furthermore, the laser emitting unit also includes a first reflector; the optical path transceiver unit includes a receiving lens, a second reflector and a multi-faceted reflector; the combined optical axis in the laser emitting unit is parallel to the optical axis of the receiving lens; the first reflector and the second reflector are parallel, and both are inclined at 45° to the optical axis of the receiving lens; the outgoing laser of the all-in-one laser transmitter is sent to the detection target via the first reflector, the second reflector and the multi-faceted reflector in sequence, and the echo signal returned by the detection target is sent to the weak light detection unit via the multi-faceted reflector, the second reflector and the receiving lens in sequence.

[0011] Furthermore, the polygonal reflector is mounted on a rotating device, and the rotating device drives the polygonal reflector to rotate to achieve laser scanning detection of the detection target.

[0012] Furthermore, the laser radar device also includes a camera mounting bracket; the digital camera, the camera mounting bracket and the laser radar host are detachably connected via threads.

[0013] Furthermore, the camera mounting frame is provided with a plurality of positioning pins and positioning pin holes for positioning the digital camera, the camera mounting frame and the laser radar host when they are restored and installed.

[0014] Furthermore, the accuracy of the positioning pin and the positioning pin hole is within 0.02 mm.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0016] The present invention is implemented through multiple laser emissions and one weak light detection. Under the condition of ensuring that the detection distance remains unchanged, the object measurement rate is increased exponentially by increasing the scanning point density, while ensuring low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 Schematic diagram of the structure of an all-in-one laser transmitter according to an embodiment of the present invention.

[0019] Figure 2 Schematic diagram of the structure of an optical path transceiver unit according to an embodiment of the present invention.

[0020] Figure 3 Schematic diagram of the connection relationship between the digital camera and the laser radar host according to an embodiment of the present invention.

[0021] Figure 4 FIG. 4 is a schematic structural diagram of a digital camera according to an embodiment of the present invention.

[0022] Figure 5 Schematic diagram of the structure of the laser radar host according to an embodiment of the present invention.

[0023] Figure 6 Schematic diagram of the structure of a camera mounting bracket according to an embodiment of the present invention.

[0024] Figure numerals: 10-laser emitting unit, 11-first reflector, 20-optical path transceiver unit, 21-second reflector, 22-polygonal reflector, 23-receiving lens, 24-rotating device, 30-weak light detection unit, 31-digital camera, 32-laser radar host, 33-camera mounting bracket, 311-camera electrical male interface, 312-grounding wire spring pin, 313-power supply line spring pin, 314-trigger line spring pin, 315-exposure signal line spring pin, 316-positioning pin one, 317-positioning pin two, 318-threaded hole, 321-camera electrical female male interface, 322-grounding wire female head, 323-power supply line female head, 324-trigger line female head, 325-exposure signal line female head, 326-positioning pin hole one, 327-positioning pin hole two. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0026] like Figure 1-3 As shown, a multi-transmitter and single-receiver low-cost laser radar device of the present invention comprises: a laser emitting unit 10, an optical path transceiver unit 20, a weak light detection unit 30, a digital camera 31 and a laser radar host 32; the laser emitting unit 10 is an all-in-one laser transmitter, which combines the optical axes of lasers emitted by multiple lasers into the same optical axis, and then the emitted laser is sent to the detection target via the optical path transceiver unit 20, and the echo signal returned by the detection target is sent to the weak light detection unit 30 via the optical path transceiver unit 20; the digital camera 31 is electrically connected to the laser radar host 32 through a pin, and is used to shoot the detection target and transmit the shooting data to the laser radar host 32; the laser radar host 32 is used to receive and process the shooting data of the digital camera 31 and to power the digital camera 31 and perform time synchronization control.

[0027] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0028] In some embodiments, the all-in-one laser transmitter includes N lasers and a collimating beam expander; the optical axes of the N lasers emitting lasers are merged into one optical axis after passing through the collimating beam expander, so that the receiving optical path and the reflected optical path can adopt existing mature technologies and manufacturing processes.

[0029] like Figure 1 As shown, lasers 1 to N are arranged according to a certain rule (for example, a circular array with a certain axis as the reference), and the optical axes of lasers 1 to N are parallel. After passing through the collimating beam expander, the optical axes of each laser are merged into one optical axis, that is, Figure 1The common optical axis after the multiple laser optical paths in the laser radar are coaxial. The N lasers can be composed of cheap and mature diode pulse lasers, which can realize long-distance measurement greater than 300m while ensuring that the single pulse capability is not reduced, and multiply the measurement rate and the spatial resolution of the original collected data, while reducing the cost of the laser radar. For actual aerial survey operations (including power inspection operations), long-distance measurement is a prerequisite for ensuring flight safety and adaptability to different terrain conditions. At the same time, a weak light detection unit 30 is used to receive and process the echo signals generated by multiple laser emissions, instead of using multiple detectors corresponding to the laser emissions to process the echo signals, which further reduces the cost and difficulty of laser radar implementation. In other words, the present invention is mainly implemented through multiple laser emissions and one weak light detection. While ensuring that the detection distance remains unchanged, the measurement rate of the object is increased exponentially by increasing the scanning point density, while ensuring low cost.

[0030] like Figure 2 As shown, in some embodiments, the laser emitting unit 10 further includes a first reflector 11; the optical path transceiver unit 20 includes a receiving lens 23, a second reflector 21 and a multi-faceted reflector 22; the combined optical axis in the laser emitting unit 10 is parallel to the optical axis of the receiving lens 23; the first reflector 11 and the second reflector 21 are parallel, and both are inclined at 45° to the optical axis of the receiving lens 23; the outgoing laser of the multi-in-one laser transmitter is sent to the detection target through the first reflector 11, the second reflector 21 and the multi-faceted reflector 22 in sequence, and the echo signal returned by the detection target is sent to the weak light detection unit 30 through the multi-faceted reflector 22, the second reflector 21 and the receiving lens 23 in sequence. It should be noted that the size and installation position of the second reflector 21 do not block all echo signals, so the receiving lens 23 can receive the echo signal.

[0031] In some embodiments, the multi-faceted reflector 22 is mounted on a rotating device 24, and the rotating device 24 drives the multi-faceted reflector 22 to rotate to realize laser scanning detection of the detection target. That is to say, the common optical axis after the multiple laser light paths are coaxial, the laser is reflected to the second reflector 21 coaxial with the receiving lens 23 through the first reflector 11; the outgoing laser is reflected to the multi-faceted reflector 22 through the second reflector 21, and the laser outgoing direction is changed by the rotation of the multi-faceted reflector 22 to realize scanning. The multi-faceted reflector 22 can be a four-sided prism, a six-sided prism, etc., and its rotation axis should be perpendicular to the laser emitting unit 10 or the receiving lens 23; and the rotating device 24 is generally controlled by a motor.

[0032] like Figure 4 , Figure 5 As shown, Figure 4The ground wire spring pin 312, the power line spring pin 313, the trigger line spring pin 314 and the exposure signal line spring pin 315 in the camera electrical male interface 311 on the digital camera 31 are respectively connected to Figure 5 The ground wire female connector 322 , the power line female connector 323 , the trigger line female connector 324 and the exposure signal line female connector 325 in the camera electrical female interface in the laser radar host 32 correspond one to one.

[0033] In some embodiments, the laser radar device further includes a camera mounting bracket 33; the digital camera 31, the camera mounting bracket 33 and the laser radar host 32 are detachably connected via threads.

[0034] like Figure 6 As shown, the digital camera 31 is connected to the laser radar host 32 through the camera mounting bracket 33 and fixed in position through the threaded hole 328. When the camera mounting bracket 33 is pressed onto the laser radar host 32 through the thread, the ground wire spring pin 312, the power line spring pin 313, the trigger line spring pin 314 and the exposure signal line spring pin 315 in the camera electrical male interface 311 on the digital camera 31 are pressed by the spring force generated by the spring. Figure 4 The ground wire female connector 322, the power supply wire female connector 323, the trigger wire female connector 324 and the exposure signal wire female connector 325 in the camera electrical female interface in the laser radar host 32 are tightly connected.

[0035] In some embodiments, the camera mounting bracket 33 is provided with a plurality of positioning pins and positioning pin holes for positioning the digital camera 31, the camera mounting bracket 33 and the laser radar host 32 when they are restored and installed.

[0036] During camera installation, Figure 6 The first positioning pin 316 and the second positioning pin 317 of the camera mounting bracket 33 are respectively connected to Figure 5 The first positioning pin hole 326 and the second positioning pin hole 327 in the laser radar host 32 correspond to each other, and the accuracy of the positioning pin and the positioning pin hole is controlled within 0.02mm, ensuring that the spring pin of the camera electrical interface on the digital camera 31 and the female head in the camera electrical interface on the laser radar are accurately positioned and connected. The positioning accuracy of the two positioning pins and the positioning pin holes is 0.02mm, and the relative distance is 60mm, so the rolling error is 3.3×10 -4 rad, when flying at an altitude of 600m, the maximum deviation caused is less than 20cm, which is less than the error requirement of no more than 20cm for surveying and mapping data results in automatic aerial triangulation. In the process of orthophoto processing, the software can automatically find the same-name connection points of adjacent images, so that orthophoto processing can be carried out directly without calibration, simplifying the aerial survey operation process.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-transmitter and single-receiver low-cost laser radar device, characterized in that: include: A laser emitting unit, an optical path transceiver unit, a weak light detection unit, a digital camera and a laser radar host; the laser emitting unit is an all-in-one laser emitter, which combines the optical axes of lasers emitted by multiple lasers into the same optical axis, and then sends the emitted laser to the detection target via the optical path transceiver unit, and the echo signal returned by the detection target is sent to the weak light detection unit via the optical path transceiver unit; the digital camera is electrically connected to the laser radar host through a pin, and is used to shoot the detection target and transmit the shooting data to the laser radar host; the laser radar host is used to receive and process the shooting data of the digital camera, and to power the digital camera and perform time synchronization control; The all-in-one laser transmitter comprises N lasers and a collimating beam expander; the optical axes of the N lasers emitting laser light are merged into one optical axis after passing through the collimating beam expander; The laser emitting unit also includes a first reflector; the optical path transceiver unit includes a receiving lens, a second reflector and a multi-faceted reflector; the combined optical axis in the laser emitting unit is parallel to the optical axis of the receiving lens; the first reflector and the second reflector are parallel, and both are inclined at 45° to the optical axis of the receiving lens; the outgoing laser of the all-in-one laser emitter is sent to the detection target via the first reflector, the second reflector and the multi-faceted reflector in sequence, and the echo signal returned by the detection target is sent to the weak light detection unit via the multi-faceted reflector, the second reflector and the receiving lens in sequence; the multi-faceted reflector is installed on a rotating device, and the multi-faceted reflector is driven to rotate by the rotating device to realize laser scanning detection of the detection target.

2. The multi-transmit and single-receive low-cost laser radar device according to claim 1, characterized in that: The laser radar device also includes a camera mounting frame; the digital camera, the camera mounting frame and the laser radar host are detachably connected via threads.

3. The multi-transmit and single-receive low-cost laser radar device according to claim 2, characterized in that: The camera mounting frame is provided with a plurality of positioning pins and positioning pin holes for positioning the digital camera, the camera mounting frame and the laser radar host when they are restored and installed.

4. The multi-transmit and single-receive low-cost laser radar device according to claim 3 is characterized in that: The accuracy of the positioning pin and the positioning pin hole is within 0.02mm.

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