CN105068085B - High accuracy list motor transmission laser radar three-dimensional scanning instrument - Google Patents

Abstract

The invention discloses a high-precision single-motor driven laser radar three-dimensional scanner. On the one hand, it realizes continuous scanning in the whole space by using a single high-precision servo motor to control the scanner, which makes the scanner more compact and reduces the cost. At the same time, the gears are replaced by worm gears and worms, and the one-way transmission eliminates the return error of the gears, improves the accuracy of the laser radar scanner, reduces the volume of the scanner, and uses two angle sensors with ±0.001° accuracy for horizontal and The vertical scanning angle is recorded, which makes the measurement of the scanning laser radar system more accurate and reliable. At the same time, the use of the wireless dual-axis ultra-high-precision pitch angle sensor also enables the high-precision single-motor drive laser radar 3D scanner to start the scanning head. Automatic horizontal calibration simplifies the preparatory work for measurement and improves the working efficiency of the scanner.

Description

High-precision single motor drive lidar 3D scanner

technical field

The invention relates to the technical field of laser radar, in particular to a high-precision single-motor driven laser radar three-dimensional scanner.

Background technique

With the rapid development of my country's aerospace industry, people's demand for non-contact atmospheric composition measurement, wind field data measurement, distance measurement, speed measurement, image target recognition and other technical methods is increasing. LiDAR is the solution to the above problems good plan. Due to the highly collimated characteristics of the laser, in order to achieve large-area detection, scanning lidar has been widely used. Among them, the 3D scanner is an important part of the scanning lidar.

Three-dimensional scanners are divided into transmissive scanners and reflective scanners. Due to the dispersion difference (absorption) of the transmissive scanner and the different transmittance of different wavelengths of laser light, certain measurement errors occur in the transmissive scanner during use. Reflective scanners are more widely used, in particular, secondary reflective scanners using the periscope principle are the most widely used. The WindTracer coherent wind lidar of CLRphotonics in the United States and the WindCube lidar of LEOSPHERE in France use secondary reflection scanners based on the periscope principle.

However, the reflective scanners currently used on lidar have the following difficulties:

1. The scanning angle error of the scanner will cause the error of the actual detection target range. As shown in Figure 1, there is the following relationship between the scanner angle error Δθ and the error Δd (ie ΔX) between the detection distance L and the detection target range:

Δd＝Δθ·L·π/180°

Therefore, in the case of a detection distance of 10 km, a scanning angle error of ±0.1° will result in an error of ±17.44m in the detection target range, which has a serious impact on the measurement of atmospheric parameters for precise positioning of lidar.

2. The detection target range of the laser radar is directly related to the scanning angle of the scanner. In WindCube, its detection direction (azimuth and elevation angle) is sent by computer to two high-precision servo motors working independently to determine and realize space scanning. In fact, there is a deviation between the detected detection direction and the actual detection direction. The reason is that the existing scanners use pure gear transmission, and under the existing machining accuracy conditions, the return error of the gear cannot be avoided (as shown in Figure 3). Even if high-precision pointing is achieved at the initial stage of assembly and adjustment, as the gears wear out, there will be deviations between the actual scanning angle range of the scanner and the rotation angle range of the servo motor.

3. Use a high-precision servo motor to control the scanning angle of the scanner. If you do not introduce a real-time angle detection system to calibrate the scanning angle and actually obtain the current azimuth angle, it is impossible to avoid vibrations in the transmission process, device manufacturing errors, and gears. Rotation angle error of the scanner caused by return stroke error, thermal expansion and contraction, mechanical wear, etc. Using a traditional angle sensor to detect the rotation angle of the scanner is limited by the cable of the sensor, so that the scanner cannot continuously scan clockwise or counterclockwise.

4. The currently used periscope-type 3D continuous scanner uses two high-precision servo motors to control the horizontal and vertical scanning of the scanner respectively. However, in the specific application of laser radar, the 3D scanner generally performs RHI, VAD or PPI scanning; for Any of the above scanning methods is a scanning of a single degree of freedom in the hemispherical space, so the use of dual motors is redundant, which increases the cost and reduces the operational reliability.

Contents of the invention

The purpose of the present invention is to provide a high-precision single-motor-driven laser radar three-dimensional scanner, which realizes the continuous scanning of the whole space of the scanner controlled by a single high-precision servo motor, improves the precision of the laser radar scanner, and reduces the scanner's size. The volume simplifies the operation process of the scanner and makes the measurement of the scanning laser radar system more accurate and reliable.

The purpose of the present invention is achieved through the following technical solutions:

A high-precision single-motor drive lidar three-dimensional scanner, including: high-precision servo motor 1, worm with clockwise backstop 2, worm with counterclockwise backstop 3, inner cylinder worm wheel 4, scanner inner cylinder 5. Inner cylinder gear sets 6 and 7, wireless two-axis ultra-high precision pitch angle sensor 8, pitch angle sensor power module 9, outer cylinder worm gear 10, scanner outer cylinder 11, ring angle encoder 12, bearing group 13 and laser Radar housing 17;

The high-precision servo motor 1 is respectively connected with the worm 2 with a clockwise backstop and the worm 3 with a counterclockwise backstop, and the worm 2 with a clockwise backstop passes through the worm gear installed at the lower end of the inner cylinder 5 of the scanner. 4. Drive the scanner inner cylinder 5 to rotate, and the upper part of the scanner inner cylinder is equipped with inner cylinder gear sets 6 and 7, so that the horizontally rotating scanner inner cylinder 5 can be converted to scan in the vertical direction of the scanner; with a counterclockwise backstop The worm 3 drives the scanner outer cylinder 11 to rotate horizontally through the outer cylinder worm wheel 10 installed at the lower end of the scanner outer cylinder 3, so as to realize the horizontal scanning of the scanner; the encoder of the ring angle encoder 12 is fixed on the lidar housing 17 , the code disc is fixed on the scanner outer cylinder 11; the wireless dual-axis ultra-high-precision angle sensor 8 is fixed on the outer wall of the scanner inner cylinder 5, and a pitch angle sensor power module 9 is built in it; the scanner inner cylinder 5 and the scanning The outer cylinder 11 of the instrument, and the outer cylinder 11 of the scanner and the lidar housing 17 are connected through a bearing group 13;

The way to achieve horizontal rotation and angle detection is as follows: set a horizontal scanning angle by the control computer, and control the high-precision servo motor 1 to rotate counterclockwise, and the high-precision servo motor 1 drives the worm 3 with counterclockwise backstop to rotate, The worm gear 10 of the outer tube is driven by the worm 3 with a counterclockwise backstop, and the worm gear 10 drives the outer tube 11 of the scanner to rotate. The cylinder rotates together, and the encoder of the ring angle encoder 12 is fixed on the lidar housing 17 to record the rotation angle of the outer cylinder;

The way to achieve vertical rotation and angle detection is as follows: a vertical scanning angle is set by the control computer, and the high-precision servo motor 1 is controlled to rotate clockwise, and the high-precision servo motor 1 drives the worm 2 with a clockwise backstop to rotate, The worm gear 4 of the inner cylinder is driven by the worm 2 with a clockwise backstop, and the worm gear 4 of the inner cylinder drives the inner cylinder 5 of the scanner, and the horizontal rotation of the inner cylinder 5 of the scanner is converted into scanning through the inner cylinder gear set 6 and 7. The head rotates in the vertical direction, while the wireless two-axis ultra-high-precision pitch angle sensor 8 records the vertical rotation angle of the scanning head in real time.

Furthermore, the worm 2 with a clockwise backstop and the worm 3 with a counterclockwise backstop are both used as sockets between the worm and the backstop. By connecting the high-precision servo motor 1, the use of a high-precision servo When the motor rotates clockwise, it controls the scanner to scan in the horizontal direction; when it rotates counterclockwise, it controls the scanner to scan in the vertical direction.

Further, when the scanner is turned on, the wireless two-axis ultra-high-precision pitch angle sensor 8 detects the horizontal orientation of the scanning head, and feeds back to the control computer through a wireless signal, and the control computer controls the high-precision servo motor 1 to rotate clockwise, driving the belt The worm 2 of the clockwise backstop rotates, and the worm gear 4 of the inner cylinder is driven by the worm 2 with the clockwise backstop. The worm gear 4 of the inner cylinder converts the horizontal rotation of the inner cylinder into the vertical rotation of the scanning head through the gear set 6 and 7. Rotate in the direction until the scanning head is at the zero position vertically upward, so as to realize the automatic horizontal calibration of the scanner when it is turned on.

Further, the accuracy of the wireless two-axis ultra-high-precision pitch angle sensor 8 and the ring angle encoder 12 are both ±0.001°, by reading the data of these two sensors, the actual rotation angle of the scanner is recorded in real time, and In subsequent data processing, the rotation angle data is corrected.

Further, it also includes: protective lens 15 and rain shield 16;

The protective lens 15 is arranged above the scanning head, and the rain shield 16 is arranged at the contact position between the lidar casing and the scanner outer cylinder 11 .

As can be seen from the technical scheme provided by the present invention above,

(1) Use a high-precision servo motor to record the scanning angle in real time through a ±0.001° ring encoder in the horizontal rotation direction and a ±0.001° wireless dual-axis ultra-high-precision pitch angle sensor in the vertical direction, which solves the problem caused by the rotation angle of the servo motor The problem of the scanner rotation angle error caused by the discrepancy with the actual rotation angle has achieved an angle error of less than ±0.001° in the horizontal direction and an angle error of less than ±0.001° in the vertical direction, reducing the horizontal detection range error of the laser radar at 10km to ± 0.17m, the vertical detection range error is reduced to ±0.17m.

(2) By using a worm with a backstop, a single high-precision servo motor controls the scanner for 360° uninterrupted continuous three-dimensional scanning. At the same time, due to the one-way rotation scanning characteristic of the backstop, the return error caused by the two-way transmission of the gear is avoided, and under the existing domestic machining level, the manufacturing accuracy and wear resistance of the worm are higher than that of the gear.

(3) Using a single high-precision servo motor reduces the volume and complexity of the scanner.

(4) Using ±0.001° wireless dual-axis ultra-high-precision pitch angle sensor, the automatic horizontal calibration of the scanning head is realized, which avoids manual calibration when used on potholes, and reduces the operation complexity of the scanning laser radar system to improve the measurement accuracy.

(5) A detachable protective lens is added to the light outlet of the scanning head. The optical path of the telescope is connected horizontally with the optical path of the scanning head, which can protect the telescope system. A rainproof device is installed between the outer cylinder of the scanner and the casing to prevent rainwater from intruding into the instrument through the gap between the scanner and the casing.

(6) The vertical scanning is realized by the transmission of the gear set, and the precise angular positioning is realized by a high-precision position sensor. This method avoids the winding problem caused by the dual-motor two-dimensional scanning, making the overall scanning structure more compact and the position pointing accuracy higher Higher degree of freedom of rotation.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings on the premise of not paying creative work.

Fig. 1 is a schematic diagram of the detection target range error caused by the scanning angle error of the scanner provided by the background technology;

Fig. 2 is a schematic diagram of the backstroke error of the gear provided by the background technology;

Fig. 3 is a structural cross-sectional view of a high-precision single-motor driven lidar three-dimensional scanner provided by an embodiment of the present invention;

FIG. 4 is a cross-sectional view of a laser radar provided by an embodiment of the present invention;

5 is a schematic diagram of a wireless two-axis ultra-high-precision pitch angle sensor provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of an annular angle encoder provided by an embodiment of the present invention;

Fig. 7 is a schematic diagram of the data recording format provided by the embodiment of the present invention using the PPI scanning method and using the actual reading value of the sensor as the coordinate value for data recording.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The embodiment of the present invention provides a high-precision single-motor-driven laser radar three-dimensional scanner. Its structural cross-sectional view is shown in Figure 3, which mainly includes: Backstop worm 3, inner tube worm gear 4, scanner inner tube 5, inner tube gear sets 6 and 7, wireless dual-axis ultra-high precision pitch angle sensor 8, pitch angle sensor power module 9, outer tube worm gear 10, scanning Instrument outer cylinder 11, ring angle encoder 12, bearing group 13, internal mirror 14, protective lens 15, rain shield 16, lidar housing 17;

The high-precision servo motor 1 is respectively connected with the worm 2 with a clockwise backstop and the worm 3 with a counterclockwise backstop, and the worm 2 with a clockwise backstop passes through the worm gear installed at the lower end of the inner cylinder 5 of the scanner. 4. Drive the inner cylinder 5 of the scanner to rotate, and the inner cylinder gear set 6 and 7 are installed on the upper part of the inner cylinder of the scanner, so that the horizontally rotating inner cylinder 5 of the scanner can be converted to scan in the vertical direction of the scanner.

The worm 3 with counterclockwise backstop drives the scanner outer cylinder 11 to rotate horizontally through the outer cylinder worm wheel 10 installed at the lower end of the scanner outer cylinder 11, thereby realizing horizontal scanning of the scanner. At the same time, the encoder of the annular angle encoder 12 is fixed on the laser radar housing 17, and its code disc is fixed on the scanner outer cylinder 11, which can rotate together with the scanner outer cylinder 11, thereby scanning the scanner outer cylinder 11 horizontally. The angle is recorded in real time.

The wireless dual-axis ultra-high-precision angle sensor 8 is fixed on the outer wall of the scanner inner cylinder 5 (near the scanning head), and it is built with a pitch angle sensor power module 9, which records the vertical scanning angle of the scanner inner cylinder in real time.

Simultaneously, the inner cylinder 5 of the scanner is connected to the outer cylinder 11 of the scanner through the bearing group 13, and the outer cylinder 11 of the scanner and the lidar shell 17 are also connected through the bearing group 13, and the outer cylinder 11 of the scanner is connected to the laser beam. Between the radar housings, a rain shield 16 is used to protect the interior of the scanner from interference from the external environment. A replaceable protective lens 15 is adopted at the scanning head, which is convenient for future maintenance.

The light propagation principle of the high-precision single-motor-driven laser radar 3D scanner provided by the embodiment of the present invention is similar to the principle of the existing periscope; its shape and structure are similar to the laser radar device described in Figure 1 (the cube device in the lower left corner of Figure 1 ) , in order to facilitate the understanding of its external structure can refer to Figure 4, that is, the laser radar housing 17 described in this embodiment is similar to the cube housing in Figure 1, and the position of the scanner in the laser radar is similar to that of the scanner on the top of the cube in Figure 1 .

In the embodiment of the present invention, a wireless two-axis ultra-high-precision pitch angle sensor 8 is used, so that the high-precision single-motor-driven lidar three-dimensional scanner can realize the automatic level calibration of the scanner when it is turned on. The calibration process is as follows:

When the scanner is turned on, the wireless two-axis ultra-high-precision pitch angle sensor 8 (powered by the pitch angle sensor power module 9) installed near the scan head (the light outlet in Fig. 3) detects the horizontal orientation of the scan head, and passes The wireless signal is fed back to the control computer, and the control computer controls the high-precision servo motor 1 to rotate clockwise, driving the worm 2 with a clockwise backstop to rotate, and the worm 2 with a clockwise backstop to drive the inner tube worm gear 4 to rotate, and the inner cylinder The barrel worm gear 4 is installed at the lower end of the inner barrel 5 of the scanner, and the horizontal rotation of the inner barrel is converted into the vertical rotation of the scanning head through the inner barrel gear sets 6 and 7 until the scanning head is at the vertically upward zero position.

In addition, the way to achieve horizontal rotation and angle detection is as follows: a horizontal scanning angle is set by the control computer, and the high-precision servo motor 1 is controlled to rotate counterclockwise, and the high-precision servo motor 1 drives the worm 3 with a counterclockwise backstop Rotate, and the worm gear 10 of the outer cylinder is driven by the worm 3 with a counterclockwise backstop, the worm gear 10 drives the outer cylinder 11 of the scanner to rotate, and the code disc of the annular angle encoder 12 installed on the outer cylinder follows the scanner outside The cylinder 11 rotates together, and the encoder of the ring angle encoder 12 is fixed on the lidar housing (17), thereby recording the rotation angle of the outer cylinder;

The way to achieve vertical rotation and angle detection is as follows: a vertical scanning angle is set by the control computer, and the high-precision servo motor 1 is controlled to rotate clockwise, and the high-precision servo motor 1 drives the worm 2 with a clockwise backstop to rotate, The inner tube worm gear 4 is driven to rotate by the worm 2 with a clockwise backstop. The inner tube worm gear 4 is installed at the lower end of the inner tube 5 of the scanner, and the horizontal rotation of the inner tube is converted into a scanning head through the inner tube gear set 6 and 7. Rotation in the vertical direction, while the wireless dual-axis ultra-high-precision pitch angle sensor 8 records the vertical rotation angle of the scanning head in real time.

In the embodiment of the present invention, the accuracy of the wireless two-axis ultra-high-precision pitch angle sensor 8 and the ring angle encoder 12 are both ±0.001°, and the schematic diagram of the wireless two-axis ultra-high-precision pitch angle sensor 7 is shown in Figure 5 As shown, the schematic diagram of the ring angle encoder 12 is shown in FIG. 6 . At the same time, in the embodiment of the present invention, the method of directly reading the rotation angle of the scanning head is used to reduce the measurement target range error of the laser radar caused by the angular scanning error of the scanner; for example, as shown in Figure 7, it is Schematic diagram of the data recording format for data recording using the PPI (horizontal) scanning method and using the actual reading value of the sensor as the coordinate value for data recording.

Above-mentioned scheme of the present invention, mainly obtained following beneficial effect:

1) Use a high-precision servo motor to record the scanning angle in real time through a ±0.001° ring encoder in the horizontal rotation direction and a ±0.001° wireless dual-axis ultra-high-precision pitch angle sensor in the vertical direction. The problem of the scanner rotation angle error caused by the discrepancy of the actual rotation angle has achieved an angle error of less than ±0.001° in the horizontal direction and an angle error of less than ±0.001° in the vertical direction, reducing the horizontal detection range error of the laser radar at 10km to ±0.17 m, the vertical detection range error is reduced to ±0.17m.

2) By using a worm with a backstop, a single high-precision servo motor controls the scanner for 360° uninterrupted continuous three-dimensional scanning. At the same time, due to the one-way rotation scanning characteristic of the backstop, the return error caused by the two-way transmission of the gear is avoided, and under the existing domestic machining level, the manufacturing accuracy and wear resistance of the worm are higher than that of the gear.

3) Using a single high-precision servo motor reduces the volume and complexity of the scanner.

4) The use of ±0.001° wireless dual-axis ultra-high-precision pitch angle sensor realizes the automatic horizontal calibration of the scanning head when it is turned on, avoids manual calibration when used on potholes, and reduces the operational complexity of the scanning laser radar system , which improves the measurement accuracy.

5) A detachable protective lens is added to the light outlet of the scanning head. The optical path of the telescope is connected horizontally with the optical path of the scanning head, which can protect the telescope system. Use a rain shield at the contact point between the lidar shell and the scanner outer cylinder to prevent the interior of the instrument from being affected by the adverse external environment.

6) The vertical scanning is realized by the transmission of the gear set, and the precise angular positioning is realized by the high-precision position sensor. This method avoids the winding problem caused by the two-dimensional scanning of the dual motors, making the overall scanning structure more compact and the position pointing accuracy higher , The degree of freedom of rotation is stronger.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (5)

1. A high-precision single-motor transmission laser radar three-dimensional scanner is characterized in that, comprising: a high-precision servo motor (1), a worm screw (2) with a clockwise backstop, a worm screw (2) with a counterclockwise backstop ( 3), inner tube worm gear (4), scanner inner tube (5), inner tube gear set (6) and (7), wireless two-axis ultra-high precision pitch angle sensor (8), pitch angle sensor power module (9 ), outer cylinder worm gear (10), scanner outer cylinder (11), annular angle encoder (12), bearing set (13) and lidar housing (17); The high-precision servo motor (1) is respectively connected with the worm (2) with a clockwise backstop and the worm (3) with a counterclockwise backstop, and the worm (2) with a clockwise backstop is installed on the scanner The inner cylinder worm gear (4) at the lower end of the inner cylinder (5) drives the scanner inner cylinder (5) to rotate, and the inner cylinder gear set (6) and (7) are installed on the upper part of the scanner inner cylinder, so that the horizontally rotating scanner inner cylinder The cylinder (5) is converted into the vertical scanning of the scanner; the worm (3) with a counterclockwise backstop drives the scanner outer cylinder ( 11) Rotate horizontally, so as to realize the horizontal scanning of the scanner; the encoder of the ring angle encoder (12) is fixed on the lidar shell (17), and its code disc is fixed on the outer cylinder (11) of the scanner; the wireless two-axis The ultra-high-precision angle sensor (8) is fixed on the outer wall of the scanner inner cylinder (5), and it has a built-in pitch angle sensor power module (9); the scanner inner cylinder (5) and the scanner outer cylinder (11), and Both the scanner outer cylinder (11) and the laser radar housing (17) are connected through a bearing group (13); The way to achieve horizontal rotation and angle detection is as follows: set a horizontal scanning angle by the control computer, and control the high-precision servo motor (1) to rotate counterclockwise, and the high-precision servo motor (1) drives the counterclockwise backstop The worm (3) rotates, and the worm gear (10) of the outer cylinder is driven by the worm (3) with a counterclockwise backstop, and the worm gear (10) of the outer cylinder (10) drives the rotation of the outer cylinder (11) of the scanner, and is installed outside the scanner The code disc of the annular angle encoder (12) on the cylinder (11) rotates together with the outer cylinder, and the encoder of the annular angle encoder (12) is fixed on the lidar shell (17) to record the rotation angle of the outer cylinder; The way to achieve vertical rotation and angle detection is as follows: set a vertical scanning angle by the control computer, and control the high-precision servo motor (1) to rotate clockwise, and the high-precision servo motor (1) drives the clockwise backstop The worm (2) rotates, and the worm gear (4) of the inner cylinder is driven by the worm (2) with a clockwise backstop, and the inner cylinder worm gear (4) drives the inner cylinder (5) of the scanner, through the inner cylinder gear set (6 ) and (7) convert the horizontal rotation of the inner cylinder (5) of the scanner into the vertical rotation of the scanning head, while the wireless dual-axis ultra-high-precision pitch angle sensor (8) records the vertical rotation angle of the scanning head in real time. 2. The high-precision single motor drive laser radar three-dimensional scanner according to claim 1, characterized in that, The worm (2) with a clockwise backstop and the worm (3) with a counterclockwise backstop are both used as sockets between the worm and the backstop. By connecting the high-precision servo motor (1), the use of one When the high-precision servo motor rotates clockwise, it controls the scanner to scan vertically; when it rotates counterclockwise, it controls the scanner to scan horizontally. 3. The high-precision single motor drive laser radar three-dimensional scanner according to claim 1, characterized in that, When the scanner is turned on, the wireless two-axis ultra-high-precision pitch angle sensor (8) detects the horizontal orientation of the scanning head, and feeds back to the control computer through a wireless signal, and the control computer controls the high-precision servo motor (1) to rotate clockwise and drive The worm (2) with a clockwise backstop rotates, and the worm (2) with a clockwise backstop drives the inner cylinder worm gear (4) to rotate, and the inner cylinder worm gear (4) passes through the gear set (6) and (7) The horizontal rotation of the inner cylinder is converted into the vertical rotation of the scanning head until the scanning head is at the vertically upward zero position, so as to realize automatic horizontal calibration of the scanner when it is turned on. 4. The high-precision single-motor drive lidar three-dimensional scanner according to claim 1, characterized in that, The accuracy of the wireless two-axis ultra-high-precision pitch angle sensor (8) and the ring angle encoder (12) are both ±0.001°. By reading the data of these two sensors, the actual rotation angle of the scanner is recorded in real time, And in the subsequent data processing, the rotation angle data is corrected. 5. The high-precision single-motor drive laser radar three-dimensional scanner according to claim 1, further comprising: a protective lens (15) and a rain shield (16); The protective lens (15) is arranged above the scanning head, and the rain shield (16) is arranged at the contact position between the lidar casing and the scanner outer cylinder (11).