Patent Publication Number: US-2022229158-A1

Title: Lidar

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of International Application No. PCT/CN2020/117266, filed Sep. 24, 2020, which claims the benefit of priority to International Application No. PCT/CN2019/107846, filed Sep. 25, 2019, China Patent Application No. CN201910912316.0, filed Sep. 25, 2019, China Patent Application No. CN201910913604.8, filed Sep. 25, 2019, and International Application No. PCT/CN2019/115026, filed Nov. 1, 2019, the contents of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present application relates to the technical field of laser detection, and in particular to a LiDAR. 
     BACKGROUND 
     Light detection and ranging (LiDAR) is a radar system that emits a laser beam to detect the position, speed and other characteristics of an object, its working principle is that an transmitting system first emits an emitted laser to the detection area, and then a receiving system receives the reflected laser reflected back from the object in the detection area, compares the reflected laser with the emitted laser, and after processing, obtains information about the object, such as distance, orientation, height, speed, posture and even shape and other parameters. 
     In order to obtain a larger working range, the LiDAR in the existing technology usually includes a rotating system, which drives a transceiver system to rotate relative to a base so as to obtain a larger field of view. The rotating system in the traditional technology generally includes a housing and a base connected to a lower end of the housing. The base has a positioning column extending upwards, which occupies the central space in the housing. In order to allow the laser generated by a laser transmitting device to be successfully emitted from the housing, certain optical elements need to be provided in the housing to adjust the path of the laser so that the laser in the housing can avoid the positioning column. However, such a structure makes the LiDAR have a complex structure and high production costs. Moreover, the transceiver device of the LiDAR is typically arranged inside the housing, which makes the assembly complicated and further and the disassembly inconvenient. 
     It is therefore necessary to provide a LiDAR without the above technical problems. 
     BRIEF SUMMARY 
     The present application provides a LiDAR. 
     According to a first aspect, the present application provides a LiDAR, including a laser transceiver system and a rotating system. The laser transceiver system is configured to emit an emitted laser and receive a reflected laser, the reflected laser is the laser reflected back by the object in the detection area; and the rotating system is disposed on one side of the laser transceiver system, and is detachably connected to the laser transceiver system. The rotating system may drive the laser transceiver system to rotate so as to change the path of the emitted laser. 
     According to a second aspect, the present application further provides a baffle fixing structure for a LiDAR. The LiDAR includes a transmitting device and a receiving device, the transmitting device is used to emit an emitted laser, the receiving device is used to receive a reflected laser reflected back by the object in the detection area, the baffle fixing structure includes an inner housing, an outer housing, and a baffle, and the transmitting device and the receiving device are all disposed in the inner housing, wherein the outer housing is sleeved outside the inner housing and spaced apart from the inner housing; the baffle includes a first isolation portion and a second isolation portion, the first isolation portion is disposed in the inner housing and isolates the transmitting device and the receiving device; and the second isolation portion extends along the edge of the first isolation portion and to the space between the inner housing and the outer housing, and is used to isolate the emitted laser and the reflected laser between the outer housing and the inner housing. 
     According to a third aspect, the present application further provides a LiDAR, which includes the baffle fixing structure provided by the second aspect of the present application, and a laser transceiver system. The laser transceiver system includes a transmitting device and a receiving device. 
     According to a fourth aspect, the present application further provides a bearing mounting structure used for a LiDAR, including a rotating body, a first housing and a bearing. The rotating body includes a driving body and a shaft body, the driving body is configured to provide driving force, the shaft body is connected to the driving body, and configured to transmit torque to an external element, and the diameter of the shaft body is smaller than the diameter of the driving body. The first housing defines an internal chamber, the rotating body is disposed in the internal chamber, and the fixing structure is disposed in the internal chamber. The bearing includes an inner ring body and an outer ring body, the inner ring body is sleeved on the outer peripheral wall of the driving body, and the outer ring body surrounds the inner ring body, and is connected to the fixing structure, so that the rotating body may rotate relative to the fixing structure while being carried by the fixing structure. 
     According to a fifth aspect, the present application further provides a LiDAR, including a laser transceiver system, a rotating system, and the bearing mounting structure set forth in the fourth aspect of the present application. The laser transceiver system is configured to emit an emitted laser and receive a reflected laser, and the reflected laser is the laser reflected back by the object in the detection area. The rotating system is disposed on one side of the laser transceiver system, and is detachably connected to the laser transceiver system, and the rotating system is configured to drive the laser transceiver system to rotate to change the path of the laser transceiver system and the reflected laser. 
     According to a sixth aspect, the present application further provides an angular displacement measurement device for the LiDAR. The angular displacement measurement device includes a base and a rotating body that rotates relative to the base, and the rotating body includes a peripheral wall that arranged around its own central axis and an end wall that located at one end of the peripheral wall and close to the base. The angular displacement measurement device includes a reflecting part and a light emitting part, the reflecting part is connected to the end wall, and includes a plurality of reflecting tooth extending toward the base and spaced from each other, each reflecting tooth is disposed in a common arc, and the arc extends around the central axis. The light emitting part may be connected to the base. When it works, it may emit and receive measurement light, the path of the measurement light is perpendicular to the central axis. When the reflecting part follows the rotating body and rotates relative to the base, the light emitting part may obtain the angle of rotation of the reflecting part relative to the light emitting part by obtaining a quantity of the reflecting teeth that the measurement light sweeps. 
     According to a seventh aspect, the present application further provides a LiDAR, which includes a base, a rotating body, and the angular displacement measurement device that is connected to the base, and configured to rotate relative to the base as set forth in the sixth aspect. 
     The present application further provides an angle adjustment method for the LiDAR in the seventh aspect, which includes: controlling the rotating body to rotate to an initial position relative to the base; obtaining a rotation angle and a rotation direction of the rotating body from the initial position to a working position; and controlling the rotating body to rotate to the working position according to the rotation angle and the rotation direction. 
     The LiDAR provided in the present application includes a laser transceiver system and a rotating system, and the laser transceiver system includes a transmitting device that may emit an emitted laser and a receiving device that may receive a reflected laser. The rotating system is disposed on one side of the laser transceiver system and is detachably connected to the laser transceiver system. The LiDAR provided in the present application separates the optical path part (that is, the laser transceiver system) from the driving part (that is, the rotating system), so that the two become two relatively independent parts. On the one hand, the path of the laser emitted by the transmitting device and the laser received by the receiving device in the laser transceiver system does not need to avoid other structures (in the prior art, it is necessary to avoid the positioning column at the center), so the structure of the laser transceiver system is simple and inexpensive. On the other hand, due to the fact that in the present application, the laser transceiver system is detachably connected to the rotating system, the two are relatively independent of each other when they are not connected, so the manufacturing processes of the two may also be independent, and both may be manufactured through a modular production process at the same time, thereby greatly increasing efficiency of production of the LiDAR. 
     The baffle fixing structure for the LiDAR provided in the present application includes an inner housing, a baffle and an outer housing. A transmitting device and a receiving device are provided in the inner housing, the transmitting device is configured to emit an emitted laser, and the receiving device is configured to receive a reflected laser. The baffle penetrates the inner housing, and includes a first isolation portion in the inner housing and a second isolation portion between the inner housing and the outer housing. The first isolation portion of the baffle is configured to isolate the emitted laser from the receiving laser, and the second isolation portion of the baffle is configured to isolate the emitted laser from the reflected laser between the outer housing and the inner housing. The foregoing structure not only avoids laser interference in the housing, but also avoids laser interference between the inner housing and the second housing, thereby improving the isolation effect between the emitted laser and the receiving laser of the LiDAR. 
     The bearing mounting structure provided in the present application includes a rotating body, the rotating body includes a driving body and a shaft body, and the shaft body is connected to a laser transceiver system of the LiDAR, and configured to transmit a torque to the LiDAR. In the present application, an inner ring body of a bearing is connected to an outer peripheral wall of the driving body of the rotating body. Compared to the structure that connects the bearing to the shaft body of the rotating body, the length of the rotating body may be reduced, thereby reducing the overall length dimension of the LiDAR. At the same time, since the length of the rotating body is reduced, the deflection of the rotating body when subjected to a bending moment is reduced, and the structural stability is thereof improved. 
     The angular displacement measurement device provided in the present application includes a reflecting part and a light emitting part. The reflecting part is connected to an end wall of the rotating body, and includes a plurality of reflecting teeth spaced from each other, and each reflecting tooth extends toward the direction of a base. The path of a measurement light emitted by the light emitting part is perpendicular to a central axis. When the reflecting part rotates with the rotating body relative to the base, the light emitting part may obtain the angle of rotation of the reflecting part relative to the light emitting part by obtaining a quantity of the reflecting teeth swept by the measurement light. Since one of the two parts of the angular displacement measurement device is disposed on the rotating body and the other one is disposed on the base, the assembly between the light emitting part and the reflecting part may be completed through the assembly of the base and the rotating body, thereby reducing the assembly process between the two parts of the light emitting part and the reflecting part, and improving the assembly efficiency. At the same time, since the reflecting teeth extend toward the direction of the base, dirt can hardly accumulate in the gap between two adjacent teeth, so the problem of low accuracy caused by dirt accumulation on the disc in the existing technology can be solved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective schematic diagram of a LiDAR provided in accordance with an embodiment of the present application; 
         FIG. 2  is a first exploded schematic diagram of a LiDAR provided in accordance with an embodiment of the present application; 
         FIG. 3  is a partial enlarged diagram of  FIG. 2 ; 
         FIG. 4  is a front view diagram of an angular displacement measurement device provided in accordance with an embodiment of the present application; 
         FIG. 5  is a second exploded schematic diagram of a LiDAR provided in accordance with an embodiment of the present application; 
         FIG. 6  is a perspective schematic diagram of a rotating body assembled with an angular displacement measurement device provided in accordance with an embodiment of the present application; 
         FIG. 7  is a top view diagram of an alternative angular displacement measurement device provided in accordance with an embodiment of the present application; 
         FIG. 8  is a partial enlarged diagram of  FIG. 7 ; 
         FIG. 9  is a top view diagram of an alternative angular displacement measurement device provided in accordance with an embodiment of the present application; 
         FIG. 10  is a flow diagram of an angle adjustment method provided in accordance with an embodiment of the present application; 
         FIG. 11  is an exploded schematic diagram of another LiDAR provided in accordance with an embodiment of the present application; 
         FIG. 12  is a first cross-sectional diagram of another type of LiDAR provided in accordance with an embodiment of the present application; 
         FIG. 13  is a second cross-sectional diagram of another type of LiDAR provided in accordance with an embodiment of the present application; 
         FIG. 14  is an exploded schematic diagram of a section view of another type of LiDAR provided in accordance with an embodiment of the present application; 
         FIG. 15  is a partial enlarged diagram of A in  FIG. 14 ; 
         FIG. 16  is a cross-sectional diagram of a base, a rotating body, a first housing, and a second housing provided in an embodiment of the present application; 
         FIG. 17  is an exploded schematic diagram of a baffle fixing structure and a laser transceiver system provided according to an embodiment of the present application; 
         FIG. 18  is a perspective schematic diagram of a combination of an inner housing, a baffle, a transmitting lens, and a receiving lens provided in accordance with an embodiment of the present application; 
         FIG. 19  is an exploded schematic diagram of a combination of an inner housing, a baffle, a transmitting lens, and a receiving lens provided in accordance with an embodiment of the present application; and 
         FIG. 20  is a cross-sectional diagram of a laser transceiver system provided in accordance with an embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION 
     The following description provides specific scenarios and requirements of the present application for the purpose of enabling those skilled in the art to make and use the contents of the present application. Various sectional modifications to the disclosed embodiments are obvious to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments shown, but is consistent with the broadest scope of the claims. 
     The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an” and “the” may include their plural forms as well, unless the context clearly indicates otherwise. When used in this disclosure, the terms “comprises,” “comprising,” “includes” and/or “including” refer to the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used in this disclosure, the term “A on B” means that A is directly adjacent to B (from above or below), and may also mean that A is indirectly adjacent to B (i.e., there is some element between A and B); the term “A in B” means that A is all in B, or it may also mean that A is partially in B. 
     In view of the following description, these and other features of the present disclosure, as well as operations and functions of related elements of the structure, and the economic efficiency of the combination and manufacture of the components, may be significantly improved. All of these form part of the present disclosure with reference to the drawings. However, it should be clearly understood that the drawings are only for the purpose of illustration and description, and are not intended to limit the scope of the present disclosure. 
     The following description can significantly improve these and other features of the present disclosure, the operation and function of related elements of the structure, as well as the economic efficiency of assembly and manufacturing of the components. It is also understood that the drawings are not drawn to scale. 
     Light detection and ranging (LiDAR) is a radar system that emits a laser beam to detect the position, speed and other characteristics of an object. Its working principle is that a transmitting device first emits an emitted laser to the detection area, and then a receiving device receives a reflected laser that is reflected back from the object in the detection area, compares the reflected laser with the emitted laser, and after processing, obtains information about the object, such as distance, orientation, height, speed, posture, and even shape and other parameters. 
     An existing mechanical LiDAR includes a rotating body and a base. The rotating body may rotate relative to the base. A laser transmitting device and a laser receiving device are disposed in the rotating body. Because the rotating body rotates relative to the base, a path of an emitted laser generated by the laser transmitting device is changed, and a purpose of detecting objects in different areas is achieved. In order to accurately detect a predetermined area, precise control of the angle of rotation of the rotating body is needed. In the prior art, an angular displacement measurement device is provided within the LiDAR to measure the angle of rotation of the rotating body relative to the base. A control center of the LiDAR controls the rotation of the rotating body by obtaining the measured value obtained by the angular displacement measurement device. The angular displacement measurement device in the prior art includes a reflective disc and an encoder, but the reflective disc has high environmental requirements, and many accumulate dirt over time, resulting in inaccurate measurements. 
     Therefore, the present application provides an angular displacement measurement device for a LiDAR.  FIGS. 1 to 9  show an angular displacement measurement device  800   a  for a LiDAR  10  according to some embodiments of the present application. The LiDAR  10  may include a base  12  and a rotating body  11  that may rotate relative to the base  12 .  FIGS. 2 to 6  show an angular displacement measurement device  800   a  for the LiDAR  10  provided according to an embodiment of the present application.  FIGS. 7 to 9  show another angular displacement measurement device  800   b  for the LiDAR  10  provided according to an embodiment of the present application. The angular displacement measurement device  800  may be the angular displacement measurement device  800   a  or the angular displacement measurement device  800   b.    
     As shown in  FIG. 1 , the rotating body  11  may rotate relative to the base  12 . A transmitting device and a receiving device (not shown in  FIG. 1 ) may be disposed in the rotating body  11 . Because the rotating body  11  rotates relative to the base  12 , a path of an emitted laser emitted by the transmitting device may be changed, and a purpose of detecting objects in different areas is achieved. Certainly, the transmitting device and the receiving device may also be disposed at other positions of the rotating body  11 , for example, on one side of the rotating body  11 , and are detachably connected to the rotating body  11 . The specific installation positions of the transmitting device and the receiving device are not limited herein. For ease of demonstration, the transmitting device and the receiving device are described in an example in which they are arranged inside the rotating body  11 . 
     The rotating body  11  may include a peripheral wall  14  and an end wall  15 . The peripheral wall  14  is arranged around its own rotating axis. The end wall  15  may be located at one end of the peripheral wall  14  and close to the base  12 . When the rotating body  11  has a cylindrical shape, the wall surface of the peripheral wall  14  may have a cylindrical surface, and the rotating axis thereof is the central axis of the cylindrical surface. In such a case, the wall surface of the end wall  15  is circular. 
     In this embodiment, the angular displacement measurement device  800  may include a reflecting part  820  and a light emitting part  810 . Angular displacement information may be transmitted by cooperation between the light emitting part  810  and the reflecting part  820 . The reflecting part  820  may be connected to the end wall  15 . The reflecting part  820  may include a plurality of reflecting teeth  821  extending toward the base  12  and spaced from each other. The reflecting teeth  821  are arranged on a common arc, and the arc extends around the rotating axis. The sentence “the reflecting teeth  821  are arranged on a common arc” indicates that there is an arc segment that can pass through all the reflecting teeth  821  in sequence. For ease of expression, the “arc” in the following refers to the arc segment passing through the reflecting teeth  821  (specifically, it may pass through the centroid of each reflecting tooth  821 ). The arc segment may have a start point and an end point, and the start point and the end point are provided with a reflecting tooth  821 . Each reflecting tooth  821  is arranged on a common arc, and each reflecting tooth  821  is arranged around the rotating axis of the rotating body  11 . 
     The light emitting part  810  may be connected to the base  12 , and configured to emit and receive a measurement light. The measurement light may specifically be laser, infrared, ultraviolet, etc. (the related principles of using light to measure linear displacement and angular displacement have been published in the prior art, and will not be repeated herein). The path of the measurement light of the light emitting part  810  may be arranged perpendicular to the central axis. Specifically, when the central axis is arranged vertically, the measurement light may be arranged horizontally. After the rotating body  11  is assembled with the base  12 , the path of the measurement light may be parallel to the end wall  15  of the rotating body  11 . 
     After the rotating body  11  is assembled relative to the base  12 , the measurement light of the light emitting part  810  is emitted to the reflecting part  820 . When the measurement light is emitted to the reflecting teeth  821 , the reflected measurement light is received by the light emitting part  810 . When the measurement light is emitted to a gap between two adjacent reflecting teeth  821 , the measurement light is not reflected, but is received by the light emitting part  810 . However, receiving positions of the above two kinds of measurement light are different. Therefore, according to the receiving position of the measurement light, it is possible to know whether the measurement light is emitted to the reflecting teeth  821 . The rotating body  11  rotates relative to the base  12 , the reflecting teeth  821  move with the rotating body  11 , and the measurement light continuously sweeps the reflecting teeth  821 . The light emitting part  810  is configured to obtain a rotation angle of the reflecting part  820  relative to the light emitting part  810  by obtaining a quantity of the reflecting teeth  821  swept by the measurement light. 
     For example, when the central angle of a line that connects the centroid of two reflecting teeth  821  to the rotating axis is ten degrees, and the receiving portion of the measurement light has changed three times (the specific process is not deduced herein since it is known in the prior art), it may be known that the rotating body  11  has rotated a total of ten degrees during the time period of the three times of changes in the receiving portion of the measurement light. The above is only an example of a specific implementation of the angle measurement that use the light emitting part  810  and the reflecting part  820 , and does not limit the structure of the angular displacement measurement device  800 , other principles may also be adopted for angular displacement measurement by using the light emitting part  810  and the reflecting part  820 , and no examples will be given herein. 
     In order to enable the light emitting part  810  to receive both the measurement light reflected by the reflecting teeth  821  and the measurement light not reflected by the reflecting teeth  821 , the light emitting part  810  may include a first working body  811  and a second working body  812  that are disposed opposite to each other. The first working body  811  is configured to transmit and receive the measurement light. The second working body  812  is configured to receive the measurement light. The reflecting teeth  821  are disposed between the first working body  811  and the second working body  812 . When the measurement light is reflected by the reflecting tooth  821 , the first working body  811  receives the reflected measurement light. When the measurement light is not reflected by the reflecting tooth  821 , the second working body  812  receives the measurement light. In particular, the light emitting part  810  may also be connected to a circuit board  13  on the base  12 , and transmits an obtained angular displacement signal of the rotating body  11  to the circuit board  13 . Therefore, the LiDAR  10  can control the rotation of the rotating body  11  according to the angular displacement signal of the rotating body  11 . 
     In this embodiment, since the light emitting part  810  of the angular displacement measurement device  800  is positioned on the base  12  of the LiDAR  10  (that is, the light-emitting part  810  has a specific structure connected to the base  12 ), the light emitting part  810  can be assembled simultaneously with other parts of the base  12 . Thus the assembling process of the light emitting part  810  does not consume too much extra man-hours. Similarly, the reflecting part  820  is mounted on the rotating body  11  (that is, the reflecting part  820  has a specific structure connected to the rotating body  11 ), thus the assembling process of the light emitting part  810  does not consume too much extra man-hours. Since the reflecting teeth  821  in  FIGS. 2 to 6  are arranged vertically (when the rotating axis of the rotating body  11  is arranged vertically), and the measuring light is arranged horizontally, the reflecting teeth  821  and the light emitting part  810  do not have positional interference in the vertical direction. That is, after the rotating body  11  of the LiDAR  10  is assembled on the base  12 , the light emitting part  810  directly cooperates with the reflecting part  820  on the rotating body  11 , and there is no need to adjust the relative positions of the reflecting teeth  821  and the light emitting part  810 . Compared with the existing technology in which the light emitting part  810  and the reflecting part  820  are assembled first (in the existing technology, these two components have positional interference in the vertical direction, so they need to be assembled in advance), and then during the process in which the rotating body  11  is assembled on the base  12 , the reflecting part  820  is installed on the rotating body  11 , and the light emitting part  810  is installed on the base  12 , the present application greatly improves the installation efficiency. 
     In this embodiment, the arc may be a circular arc, and the center of the circle where the circular arc is located is on the rotating axis. That is, there is a circular arc segment that passes through each reflecting tooth  821  (specifically, it may pass through the centroid of each reflecting tooth  821 ), and the center of the circle where the circular arc segment is located is on the rotating axis. Thanks to this structure, the relative distance between each reflecting tooth  821  that reflects the measurement light and the light emitting part  810  does not change when the rotating body  11  rotates. In the case where the reflecting teeth  821  extend between the first working body  811  and the second working body  812  of the light emitting part  810 , no matter how small the angle of rotation of the rotating body  11  is, the relative distance from each reflecting tooth  821  for reflecting the measurement light to the first working body  811  and the second working body  812  does not change, so that the path of the measurement light reflected by each reflecting tooth  821  is substantially the same, therefore the reflected measurement light is more conveniently to be received. 
     The measuring range of the angular displacement measurement device  800  may be set correspondingly according to the rotatable angle of the rotating body  11 . For example, in the case where the rotating body  11  may only rotate within a range of ninety degrees, the central angle of the circular arc that each reflecting teeth  821  is located may only be ninety degrees, that is, the maximum measurement range of the angular displacement measurement device  800  is ninety degrees. In an embodiment, in order to make the angular displacement measurement device  800  more adaptable, the central angle of the circular arc that each reflecting teeth  821  is located may be equal to three hundred and sixty degrees, that is, each reflecting tooth  821  is disposed in a circle around the rotating axis of the rotating body  11 . Specifically, the distance between every two adjacent reflecting teeth  821  may be equal. In this way, the theoretical measuring range of the angular displacement measurement device  800  may be infinite. 
     When the circular arc is less than three hundred and sixty degrees, the circular arc has two ends, so an initial position of the angular displacement measurement may be determined by finding the two ends of the circular arc (the circular arc is an imaged line which does not exist, and actually the initial position is determined by finding the position of the reflecting tooth  821  located at the end of the circular arc.) When the circular arc is three hundred and sixty degrees, and the position of each reflecting tooth  821  is distributed symmetrically about the rotating axis of the rotating body  11 , the initial position of the angular displacement measurement device  800  may not be determined. 
     In order to maximize the measuring range of the angular displacement measurement device  800  and to easily determine the initial position, as shown in  FIGS. 2 to 9 , along the extending direction of the circular arc, the reflection distances of two adjacent reflecting teeth  821  are equal. When the central angle of the circular arc is less than three hundred and sixty degrees, the two reflecting teeth  821  at the two ends of the circular arc are a first initial tooth  8211  and a second initial tooth  8212 , respectively. The distance between the first initial tooth  8211  and the second initial tooth  8212  is greater than the reflection distance and less than or equal to twice the reflection distance. When the distance between the first initial tooth  8211  and the second initial tooth  8212  is equal to twice the reflection distance, with respect to a structure in which each reflecting tooth  821  is disposed on a circle around the rotating axis and the distance between every two adjacent reflecting teeth  821  is equal, the present embodiment is equivalent to the case where one tooth is removed from the foregoing structure. Since the distance between the first initial tooth  8211  and the second initial tooth  8212  is different from the distance between other teeth, this difference may be used to determine the initial position. 
     In some embodiments, the reflecting part  820  may include only the reflecting teeth  821 . The reflecting teeth  821  may be integrated with the end wall  15  of the rotating body  11 . This eliminates the need for additional processing of the reflecting part  820 , and also eliminates the assembly process of the reflecting part  820 . Certainly, the reflecting teeth  821  may also be assembled on the end wall  15  of the rotating body  11  in a one-to-one correspondence. 
     In some embodiments, the reflecting part  820  may further include a connection member  822 . The connection member  822  may be threadedly connected to the end wall  15  of the rotating body  11 . That is, the reflecting part  820  may be connected to the end wall  15  of the rotating body  11  through the connection member  822 . Each reflecting tooth  821  is connected to the connection member  822 , so that each reflecting tooth  821  is fixed to the end wall  15  of the rotating body  11 . The connection member  822  may be integrated with the reflecting teeth  821 . When the reflecting part  820  is assembled, it is only necessary to assemble the connection member  822  on the end wall  15  of the rotating body  11  with a screw fastener. 
     In order to save materials, the connection member  822  may be elongated or curved in a circle arc shape. The central angle of the connection member  822  in shape of circle arc may be determined according to the arrangement position of each reflecting tooth  821 . As shown in  FIGS. 2 to 6 , the connection member  822  may have a circular frame shape, the connection member  822  extends around the rotating axis, and the center of the connection member  822  is located on the rotating axis. Such a structure may make the relative distance between each reflecting tooth  821  that reflect the measurement light and the light emitting part  810  unchanged when the rotating body  11  rotates. When the reflecting teeth  821  extend between the first working body  811  and the second working body  812  of the light emitting part  810 , no matter how small the angle of rotation of the rotating body  11  is, the relative distances from each reflecting tooth  821  reflecting the measurement light to the first working body  811  and the second working body  812  do not change, so that the path of the measurement light reflected by each reflecting tooth  821  is substantially the same, therefore the reflected measurement light is more conveniently to be received. 
     The angular displacement measurement device  800  needs to be disposed between the base  12  and the rotating body  11  of the LiDAR  10 , which may make the gap between the rotating body  11  and the base  12  larger, and thus is not conducive to the positioning of the rotating body  11 . In order to solve this problem, in some embodiments, a sink  16  may be provided on the end wall  15 , and the connection member  822  may be embedded in the sink  16 . The connection member  822  may be partially embedded in the sink  16 . However, in order to reduce the gap between the rotating body  11  and the base  12  as much as possible, the connection member  822  may be completely embedded in the sink  16 , that is, the depth of the sink  16  is greater than the thickness of the connection member  822  in the depth direction of the sink  16 . The reflecting teeth  821  extend out of the sink  16  for reflecting the measurement light, and the part of the reflecting teeth  821  extending out of the sink  16  reflects the measurement light. 
     A shape of the reflecting teeth  821  may be determined according to an actual situation. The reflecting teeth  821  may be rectangular teeth or tapered teeth. When the reflecting teeth  821  are rectangular teeth, a thickness of the reflecting teeth  821  along the extending direction of the arc may be set according to an actual situation. For example, the thickness of the reflecting teeth  821  in the extending direction of the arc may be equal to a distance between two adjacent rectangular teeth. 
     The reflecting teeth  821  may extend perpendicularly to the end wall  15  of the rotating body  11 , or may extend by an acute angle with the end wall  15  of the rotating body  11 . The quantity of the reflecting teeth  821  has a great influence on measurement accuracy of the angular displacement measurement device  800 . The larger the quantity of the reflecting teeth  821 , the higher the measurement accuracy of the angular displacement measurement device  800 . In order to facilitate dividing angles of integer degrees, the quantity of the reflecting teeth  821  may be an integer multiple of thirty-six. For example, the quantity of the reflecting teeth  821  may be thirty-six, seventy-two, or one hundred and eight. 
     The angular displacement measurement device  800   b  is shown in  FIGS. 7 to 9 . Compared with the angular displacement measurement device  800   a  in  FIGS. 2 to 6 , this device changes the structure of the reflecting part  820  and the light emitting direction of the light emitting part  810 . In this embodiment, the reflecting part  820  is connected to an end wall  15  of the rotating body  11 , and the reflecting part  820  also includes reflecting teeth  821  extending in a direction parallel to the end wall  15  of the rotating body  11 . The measurement light emitted by the light emitting part  810  is parallel to the rotating axis of the rotating body  11 . 
     The reflecting part  820  is in the shape of a ring-shaped plate. The outer edge of the reflecting part  820  is formed with a plurality of light transmitting holes  824  arranged in a circular array around a center thereof. Each light transmitting hole  824  has two reflecting teeth  821  on two sides thereof. The measuring light emitted by the light emitting part  810  is parallel to the rotating axis of the rotating body  11 . The measuring light is reflected when it hits the reflecting teeth  821 , while the measuring light is not reflected when it hits the light transmitting hole  824 . Regardless of whether the measuring light is reflected, the measuring light is then received by the light emitting part  810 . By analyzing the reflection of the light, the quantity of the reflecting teeth  821  swept by the measuring light can be obtained, and then the angle rotated by the reflecting part  820  can be obtained, and finally the angular displacement of the rotating body  11  can be obtained. 
     To enable the light emitting part  810  to receive both the measuring light reflected by the reflecting teeth  821  and the measuring light not reflected by the reflecting teeth  821 , the light emitting part  810  may have a first working body  811  and a second working body  812  disposed oppositely. The first working body  811  is used for transmitting and receiving the measuring light, the second working body  812  is used for receiving the measuring light, and the reflecting teeth  821  are arranged between the first working body  811  and the second working body  812 . When the measuring light is reflected by the reflecting teeth  821 , the first working body  811  receives the reflected measuring light. When the measuring light is not reflected by the reflecting tooth  821 , the second working body  812  receives the measuring light. In particular, the light emitting part  810  may also be connected to the circuit board on the base  12 , and transmit the acquired angular displacement signal of the rotating body  11  to the circuit board, so that the LiDAR can be aligned according to the angular displacement signal of the rotating body  11  to control its rotation. 
     When the reflecting teeth  821  of the reflecting part  820  extend in a direction parallel to the end wall of the rotating body  11 , the first working body  811  of the light emitting part  810  is located between the reflecting part  820  and the base  12 , and the second working body  812  of the light emitting part  810  is located between the reflecting part  820  and the end wall of the rotating body  11 . When the rotating axis of the rotating body  11  is arranged vertically, the first working body  811  of the light emitting part  810  is located below the reflecting part  820 , and the second working body  812  of the light emitting part  810  is located above the reflecting part  820 . 
     When the end wall  15  of the rotating body  11  has a sink  16 , the reflecting part  820  in this embodiment can also be embedded in the sink  16 . However, at the same time, since the light emitting part  810  is connected to the base  12 , a part of the light emitting part  810  needs to be embedded in the sink  16 . 
     In order to determine the initial position of the reflecting part  820  shown in  FIGS. 7 to 9 , it is also possible to make the width of one reflecting tooth  821  greater than the width of other reflecting teeth  821 . Specifically, the width of the reflecting tooth  821  with a wider width may be twice that of other reflecting teeth  821 . 
     The present application further provides a LiDAR  10 , which includes a base  12 , a rotating body  11 , and the angular displacement measurement device  800  in any of the foregoing embodiments. The rotating body  11  may rotate relative to the base  12 . The rotating body  11  is provided with a laser transmitting device and a laser receiving device. By rotating the rotating body  11  relative to the base  12 , the path of the laser emitted by the laser transmitting device can be changed, thereby achieving the purpose of detecting objects in different areas. The angular displacement measurement device  800  can accurately control the rotation angle of the rotating body  11 , and can accurately detect a predetermined area. The light emitting part  810  of the angular displacement measurement device  800  is provided on the base  12  of the LiDAR  10 , and the reflecting part  820  is provided on the rotating part of the LiDAR  10 . The angular displacement measurement device  800  is used to measure the rotation angle of the rotating body  11  of the LiDAR  10  relative to the base  12 . 
     It is to be noted that the angular displacement measurement device  800  may be mounted on the mechanical LiDAR  10  shown in  FIGS. 1 to 9 , or may be mounted on any other rotatable LiDAR. It is not limited herein. 
       FIG. 10  is a schematic flow diagram of an angle adjustment method according to an embodiment of the present application, which is used for angle adjustment of the LiDAR  10  shown in  FIGS. 1 to 9 . As described above, the LiDAR  10  may include a base  12  and a rotating body  11 . The rotating body  11  may rotate relative to the base  12 . A laser transmitting device and a laser receiving device are disposed in the rotating body  11 . Because the rotating body  11  rotates relative to the base  12 , a path of an emitted laser emitted by the laser transmitting device can be changed, and a purpose of detecting objects in different areas is achieved. In order to accurately detect a predetermined area, precise control of a rotation angle of the rotating body  11  is needed. The LiDAR  10  further includes an angular displacement measurement device  800 . A light emitting part  810  of the angular displacement measurement device  800  is disposed on the base  12  of the LiDAR  10 , and a reflecting part  820  is disposed on a rotating part of the LiDAR  10 . The angular displacement measurement device  800  is configured to measure the rotation angle of the rotating body  11  of the LiDAR  10  relative to the base  12 . As shown in  FIG. 10 , the angle adjustment method may include the following steps: 
     S 102 : Control the rotating body  11  to rotate to an initial position relative to the base  12 . 
     After the LiDAR  10  is turned on, the rotating body  11  of the LiDAR  10  does not immediately rotate to the working position, but first finds a reference point of the angle. That is, the rotating body  11  may first rotate to an initial position relative to the base  12 , and the initial position may be any reference point for realizing the setting. 
     S 104 : Obtain the rotation angle and the rotation direction of the rotating body  11  from the initial position to the working position. 
     After the rotating body  11  is rotated to the preset initial position, it may be rotate to the working position according to the rotation signal. In addition, since the overall position of the LiDAR  10  relative to the external environment may change, each rotation signal may be different, i.e., the data such as the angle of rotation and the direction of rotation of the rotating body  11  from the initial position to the working position may be different each time. 
     S 106 : Control the rotating body  11  to rotate to the working position according to the rotation angle and the rotation direction. 
     As described above, each reflecting tooth  821  of the angular displacement measurement device  800  of the LiDAR  10  is disposed on a common circular arc, and the center of the circle where the circular arc is located is on the rotating axis. Each reflecting tooth  821  is arranged at an equal interval. Along the extending direction of the circular arc, the distance between two adjacent reflecting teeth  821  is the reflection distance. When the central angle of the circular arc is less than three hundred and sixty degrees, the two reflecting teeth  821  at the two ends of the circular arc are the first initial tooth  8211  and the second initial tooth  8212 , respectively. The distance between the first initial tooth  8211  and the second initial tooth  8212  is greater than the reflection distance and less than or equal to twice the reflection distance. 
     The step of controlling the rotating body  11  to rotate to an initial position includes: controlling the rotating body  11  to rotate to an area that an emission path of measurement light passes through between the first initial tooth  8211  and the second initial tooth  8212 , that is, the initial position of the LiDAR  10  is determined by a difference in the distance between the first initial tooth  8211  and the second initial tooth  8212 . 
     An existing LiDAR includes a transmitting device and a receiving device, where the transmitting device is configured to emit an emitted laser, and the receiving device is configured to receive a reflected laser reflected back by an object in a detection area. To avoid interference between the emitted laser and the reflected laser in the LiDAR, a baffle needs to be disposed in the LiDAR, where the baffle is configured to isolate the emitted laser from the reflected laser, but the existing baffle is less effective in isolation. 
     Therefore, the present application provides a new LiDAR  20  and a baffle fixing structure  600  for the LiDAR  20 . 
       FIGS. 17 to 19  show a baffle fixing structure  600  for a LiDAR  20  according to an embodiment of the present application. The LiDAR  20  includes a laser transceiver system  200 . The laser transceiver system  200  may include a transmitting device and a receiving device, where the transmitting device is configured to emit an emitted laser, and the receiving device is configured to receive a reflected laser reflected back by an object in a detection area. The baffle fixing structure  600  may include an inner housing  240 , an outer housing  400 , and a baffle  670 . 
     The inner housing  240  of the baffle fixing structure  600  may define an accommodating chamber  242 . Both the transmitting device and the receiving device are disposed in the accommodating chamber  242  of the inner housing  240 . The emitted laser generated by the transmitting device may pass through the inner housing  240  to travel outside the accommodating chamber  242 , and the reflected laser may pass through the inner housing  240  to enter the accommodating chamber  242 . The emitted laser and the reflected laser are likely to interfere with each other in the accommodating chamber  242 . 
     As shown in  FIG. 17 , the outer housing  400  is sleeved over the inner housing  240  and spaced apart from the inner housing  240 . The outer housing  400  is configured to protect the inner housing  240  or other components of the LiDAR  20 . In some embodiments, in order to adjust a path of the emitted laser and that of the reflected laser, the transmitting device and the receiving device need to realize a function of rotation in the outer housing  400 . The inner housing  240  rotates together with the transmitting device and the receiving device. Therefore, in order for the inner housing  240  to rotate smoothly, a gap needs to be reserved between the outer housing  400  and the inner housing  240 , and the gap is used to prevent position interference between the inner housing  240  and the outer housing  400  when the inner housing  240  rotates. 
     As shown in  FIGS. 17 to 19 , the baffle  670  may include a first isolation portion  671  and a second isolation portion  672 . The first isolation portion  671  is disposed in the inner housing  240  and configured to isolate the transmitting device from the receiving device. The second isolation portion  672  extends along an edge of the first isolation portion  671  to the space between the inner housing  240  and the outer housing  400 , and is configured to isolate the emitted laser from the reflected laser between the outer housing  400  and the inner housing  240 . 
     The first isolation portion  671  of the baffle  670  may divide the accommodating chamber  242  into two mutually isolated working chambers. The transmitting device and the receiving device are respectively arranged in the two working chambers. Therefore, the first isolation portion  671  of the baffle  670  may be configured to isolate the emitted laser from the incident light in the inner housing  240 . The foregoing structure not only avoids laser interference in the housing, but also avoids laser interference between the inner housing  240  and the outer housing  400 , thereby achieving a better isolation effect. 
     The baffle  670  may be integrated with the inner housing  240  or may be disposed separately from the inner housing  240 . When the baffle  670  is disposed separately from the inner housing  240 , an isolation slit  244  may be disposed on the inner housing  240 . The baffle  670  passes through the isolation slit  244 . After the baffle  670  passes through the isolation slit  244 , a portion of the baffle  670  located between the inner housing  240  and the outer housing  400  is referred to as the second isolation portion  672 , and a portion of the baffle  670  located in the inner housing  240  is referred to as the first isolation portion  671 . 
     The inner housing  240  may further have a recessed portion  246 . The recessed portion  246  is recessed in a direction away from the outer housing  400 , so that a space of a certain size is formed between the inner housing  240  and the outer housing  400 . A working port  248  is disposed at the recessed portion  246  of the inner housing  240 . The LiDAR  20  further includes a transmitting lens  220  and a reflecting lens  230  (it may be understood that the reflecting lens  230  may be configured to receive the reflected laser that is reflected back, and therefore may be referred to as a receiving lens  230  in some embodiments). The emitted laser passes through the transmitting lens  220  to travel outside the inner housing  240 , and the reflected laser passes through the reflecting lens  230  to enter the inner housing  240 . The transmitting lens  220  and the reflecting lens  230  (receiving lens  230 ) are both disposed at the working port  248 . A relatively large space exists between the recessed portion  246  of the inner housing  240  and the outer housing  400 , and the emitted laser and the reflected laser respectively pass through in the space. 
     In order to prevent the emitted laser and the reflected laser in the foregoing space from interfering with each other, the isolation slit  244  of the inner housing  240  may be disposed in the recessed portion  246  of the inner housing  240 . After the baffle  670  passes through the isolation slit  244 , the foregoing space is separated into two relatively independent portions. The transmitting lens  220  and the reflecting lens  230  (receiving lens  230 ) are arranged on two opposite sides of the baffle  670  in a one-to-one correspondence. 
     The working port  248  may be a complete large hole or two independent small holes. When the working port  248  is two independent small holes, the isolation slit  244  may be located between the two small holes. 
     When the working port  248  is a large hole, the isolation slit  244  passes through the working port  248  and has an overlapping portion with the working port  248 . Specifically, the isolation slit  244  may be located in the middle of the working port  248  and divide the working port  248  into two equal parts. The transmitting lens  220  is disposed in one part of the working port  248 , and the receiving lens  230  (receiving lens  230 ) is disposed in the other part. In this case, the transmitting lens  220  and the reflecting lens  230  (receiving lens  230 ) are respectively attached to two opposite surfaces of the baffle  670 , so that the laser passing through the transmitting lens  220  and the laser passing through the reflecting lens  230  (receiving lens  230 ) are unlikely to interfere with each other. When the working port  248  is configured based on the foregoing structure, the transmitting lens  220 , the baffle  670 , and the reflecting lens  230  (receiving lens  230 ) collectively fill the working port  248 . 
     In an embodiment, the second isolation portion  672  of the baffle  670  may include a sealed edge  673  located between the outer housing  400  and the inner housing  240  and facing the outer housing  400 . The sealed edge  673  is spaced apart from an inner side wall of the outer housing  400 , and a distance between the sealed edge  673  and the inner side wall of the outer housing  400  is equal everywhere. To be specific, it may be understood that an edge of the second isolation portion  672  facing the outer housing  400  depends on a shape of an inner surface wall of the outer housing  400 . If no gap is needed between the second isolation portion  672  and the outer housing  400  (the gap is used to facilitate rotation of the baffle  670  relative to the outer housing  400 ), the sealed edge  673  of the baffle  670  may be tightly attached to the inner surface wall of the outer housing  400 . 
     In an embodiment, the outer housing  400  may be a hemispherical housing. When the outer housing  400  is a hemispherical housing, the sealed edge  673  of the baffle  670  has an arc shape that corresponds to the shape of the inner surface wall of the outer housing  400 . The hemispherical housing structure of the outer housing  400  can facilitate rotation of the inner housing  240  therein on the one hand, and can maximally save manufacturing materials on the other hand. The outer housing  400  is made of a transparent material, so that the emitted laser can pass through the outer housing  400  to travel outside the outer housing  400 , and that the reflected laser can pass through the outer housing  400  to enter the outer housing  400 . 
     As described above, the emitted laser may pass through the transmitting lens  220  to travel outside the inner housing  240 , and further pass through the outer housing  400  to travel toward a target object; and the reflected laser passes through the outer housing  400  and further passes through the reflecting lens  230  (receiving lens) to enter the inner housing  240 . 
     It may be understood that the present application further provides a LiDAR  20 , as shown in  FIG. 11  and  FIG. 12 . The LiDAR  20  includes the baffle fixing structure in any one of the foregoing embodiments. Specifically, the LiDAR  20  may further include a laser transceiver system  200  and a rotating system  100 . 
     In this embodiment, because a laser emitted by a transmitting device and a laser received by a receiving device in the laser transceiver system  200  do not need to avoid rotating parts, an optical path is simple, and no optical element for adjusting the path of the laser is needed. Therefore, an overall cost of the LiDAR  20  is reduced. In addition, because the laser transceiver system  200  is detachably connected to the rotating system  100 , the two are relatively independent when they are not connected, manufacturing processes of the two can be independent of each other, and both may be produced by modular production at the same time, thereby greatly increasing efficiency of production of the LiDAR  20 . 
     A rotating system of a LiDAR in the prior art includes a rotating body. The rotating body includes a shaft body connected to a laser transceiver system and a driving body connected to the shaft body. The driving body is configured to obtain a driving force for rotation, and the shaft body is configured to transmit a torque to the laser transceiver system. In order to facilitate the connection, a diameter of the shaft body is relatively small. In the prior art, a bearing is sleeved over the shaft body, which makes a length of the shaft body larger. Therefore, the length of the shaft body is larger, and an overall length of the LiDAR is larger. 
     Therefore, the present application provides a new LiDAR  20  and a bearing mounting structure  700  for the LiDAR  20 . 
     As shown in  FIGS. 11 to 16 , the bearing mounting structure  700  may include a rotating body  110 . In some embodiments, the bearing mounting structure  700  may further include a first housing  300  and a bearing  120 . 
     As shown in  FIGS. 11 to 16 , the rotating body  110  may include a shaft body  112  connected to a laser transceiver system  200  and a driving body  111  connected to the shaft body  112 . The driving body  111  is configured to obtain a driving force for rotation. The shaft body  112  is configured to transmit a torque to the laser transceiver system  200 . The driving body  111  may be connected to a driving device  140  (for example, a driving motor  140 ) of the LiDAR  20  to obtain the driving force of the driving device (driving motor  140 ). In order to facilitate the connection with the laser transceiver system  200  for transmitting the driving force, a diameter of the shaft body  112  is smaller than a diameter of the driving body  111 . 
     The shaft body  112  is connected to an end of the driving body  111 , and an end of the shaft body  112  away from the driving body  111  is screwed to the laser transceiver system  200 . 
     The first housing  300  defines an internal chamber  320 . The rotating body  110  is disposed in the internal chamber  320  of the first housing  300 . The internal chamber  320  of the first housing  300  is further provided with a fixing structure  310 . 
     The bearing  120  includes an inner ring body and an outer ring body surrounding the inner ring body. The inner ring body of the bearing  120  is sleeved over an outer peripheral wall of the driving body  111 , and the outer ring body of the bearing  120  is connected to the fixing structure  310  of the first housing  300 , so that the rotating body  110  can be carried by the fixing structure  310  while rotating relative to the fixing structure  310 . Balls or rollers may be disposed between the outer ring body and the inner ring body of the bearing  120 . A specific structure of the bearing  120  depends on actual needs. 
     Because the inner ring body of the bearing  120  is connected to the outer peripheral wall of the driving body  111 , in comparison with a structure that connects the bearing  120  to the shaft body  112  of the rotating body  110 , a length of the shaft body  112  can be reduced, and the connection between the bearing  120  and the outer peripheral wall of the driving body  111  does not need to increase a length of the driving body  111 . Therefore, the bearing mounting structure  700  provided in the present application can reduce an overall length of the LiDAR  20 . In addition, because the length of the shaft body  112  is reduced, deflection of the shaft body  112  when subjected to bending moments is also reduced, and structural stability thereof is thus improved. Moreover, because a diameter of a horizontal cross-section of the driving body  111  is larger, the bearing  120  may be larger, to increase an ultimate bearing capacity of the bearing  120  and make its transmission stability stronger. 
     The fixing structure  310  only needs to fix the outer ring body of the bearing  120 . However, in order to make the connection to the bearing  120  more stable, the fixing structure  310  may define an accommodating chamber  311  that penetrates both ends. The inner ring body of the bearing  120  is sleeved over the outer peripheral wall of the driving body  111 . The driving body  111  is located in the accommodating chamber  311 . The outer ring body of the bearing  120  is disposed in the accommodating chamber  311  of the fixing structure  310  and connected to an inner peripheral wall of the accommodating chamber  311 , so that the outer ring body can be fixed in all peripheral directions, thereby improving stability of the connection. 
     After the bearing  120  is connected to an inner peripheral wall of the internal chamber  320 , the bearing  120  tends to slide axially toward the inner peripheral wall (that is, when the internal chamber  320  penetrates up and down, the bearing  120  can easily slide up and down). In order to avoid the foregoing problem, an abutment flange  312  may be further provided in the internal chamber  320  of the fixing structure  310 . Specifically, the abutment flange  312  is disposed in the internal chamber  320  of the fixing structure  310 . The abutment flange  312  extends along the inner peripheral wall of the internal chamber  320  toward the center of the internal chamber  320 . The bearing  120  abuts against a surface of the abutment flange  312  that faces an outer side of the internal chamber  320 , to limit freedom of the bearing  120  to slide in an axial direction of the internal chamber  320 . It should be noted that there are two “surfaces of the abutment flange  312  that face an outer side of the internal chamber  320 ,” but in the present application, the foregoing surface specifically refers to one of the two surfaces that is close to a port of the internal chamber  320 . For example, when the internal chamber  320  penetrates up and down, if the abutment flange  312  is close to an upper port of the internal chamber  320 , the foregoing surface refers to an upper surface of the abutment flange  312 . If the abutment flange  312  is close to a lower port of the internal chamber  320 , the foregoing surface refers to a lower surface of the abutment flange  312 . 
     The abutment flange  312  may be in any shape, provided that the abutment flange  312  can restrict the sliding of the bearing  120 . However, in order to allow the abutment flange  312  to withstand a great thrust from the bearing  120 , in the present application, the abutment flange  312  may be in a ring shape, and the abutment flange  312  includes an inner hole, where an inner diameter of the inner hole of the abutment flange  312  is larger than an inner diameter of the outer ring body of the bearing  120 , so that the outer ring body of the bearing  120  is easy to disassemble. 
     The rotating body  110  may be connected to only one bearing  120 . However, when connected to one bearing  120 , the rotating body  110  is easily deflected. In the present application, the bearing mounting structure includes two bearings  120 . Inner ring bodies of the two bearings  120  are respectively sleeved over the outer peripheral wall of the driving body  111 . The two bearings  120  are respectively distributed at two ends of the driving body  111 . Further, when two bearings  120  are provided, the fixing structure  310  includes two abutment flanges  312 . The two abutment flanges  312  are arranged adjacent to two ends of the accommodating chamber  311  respectively. One of the bearings  120  abuts against a surface of one of the two abutment flanges  312  facing an outer side of the accommodating chamber  311 , and the other bearing  120  abuts against a surface of the other abutment flange  312  facing an outer side of the accommodating chamber  311 . 
     The rotating body  110  may be positioned on the fixing structure  310  by the bearing  120 , so that the rotating body  110  can rotate relative to the fixing structure  310 , that is, the fixing structure  310  of the first housing  300  provides the rotating body  110  with an upward bearing force. In addition, the first housing  300  and the rotating body  110  are connected by the bearing  120 , so that the rotating body  110  can further rotate relative to the fixing structure  310  while the fixing structure  310  provides the rotating body  110  with the upward bearing force. 
     A rotatable LiDAR in the prior art includes a housing and a base connected to a lower end of the housing. The base includes a positioning column extending upward, and the positioning column extends into an internal center of the housing. A driving device is connected between the positioning column and the housing to drive the housing to rotate relative to the positioning column. The housing has a laser transmitting device and a laser receiving device. The laser transmitting device and the laser receiving device may rotate together with the housing, to detect objects in different areas. 
       FIGS. 11 to 14  show schematic diagrams of a LiDAR  20  provided according to an embodiment of the present application. As shown in  FIGS. 11 to 14 , the LiDAR  20  may include a laser transceiver system  200 . In some embodiments, the LiDAR  20  may further include a rotating system  100 . In some embodiments, the LiDAR  20  may further include a baffle fixing structure  600  for the LiDAR  20 . In some embodiments, the LiDAR  20  may further include a bearing mounting structure  700  for the LiDAR  20 . In some embodiments, the LiDAR  20  may further include an angular displacement measurement device  800 . 
     The laser transmitting system  200  includes a transmitting device and a receiving device. The transmitting device is configured to emit an emitted laser and the receiving device is configured to receive a reflected laser. The reflected laser is the laser reflected back by an object in a detection area. After the transmitting device emits the emitted laser, the emitted laser hits the detected object in the detection area and is reflected back to the laser transceiver system  200 . The reflected laser that is reflected back is received by the receiving device. By comparing changes of related parameters between the laser emitted by the transmitting device and the laser received by the receiving device, relevant information of the detected object such as distance, orientation, height, speed, posture and even shape may be obtained. 
     The rotating system  100  is disposed on one side of the laser transceiver system  200  and detachably connected to the laser transceiver system  200 . The rotating system  100  is configured to drive the laser transceiver system  200  to rotate, to change a path of the emitted laser and a path of the reflected laser. By changing the path of the emitted laser, the path of the reflected laser is changed. By changing the path of the emitted laser and the path of the reflected laser, a sweep area of the LiDAR  20  may be changed, so that application scenarios of the LiDAR  20  are expanded. 
     The rotating system  100  may be specifically disposed in any position of the laser transceiver system  200 , and the relative positions of the two depend on actual requirements. However, for ease of description, the following uses an example of the rotating system  100  disposed below the laser transceiver system  200  for illustration. It should be noted that the rotating system  100  may also be disposed in other positions, for example, above the laser transceiver system  200  or to the left or right of the laser transceiver system  200 , and is not limited herein. 
     When the rotating system  100  is disposed below the laser transceiver system  200 , an upper end of the rotating system  100  is detachably connected to a lower end of the laser transceiver system  200 . Specifically, the two may be connected by screw connection, snap connection, magnetic attraction, etc. In order to obtain a stable driving force, rotating parts of the rotating system  100  may be screwed to the laser transceiver system  200 . 
     In this embodiment, because the laser emitted by the transmitting device and the laser received by the receiving device in the laser transceiver system  200  do not need to avoid the rotating parts, an optical path is simple, and no optical element for adjusting the path of the laser is needed. Therefore, an overall cost of the LiDAR  20  is reduced. In addition, because the laser transceiver system  200  is detachably connected to the rotating system  100 , the two are relatively independent when they are not connected, manufacturing processes of the two can be independent of each other, and both may be produced by modular production at the same time, thereby greatly increasing efficiency of production of the LiDAR  20 . 
     In an embodiment, the rotating system  100  may include a rotating body  110 . The rotating body  110  may be the rotating body  110  in the foregoing bearing mounting structure  700 . The rotating body  110  rotates around its own central axis. When the rotating system  100  is disposed below the laser transceiver system  200 , the central axis of the rotating body  110  is arranged vertically. An end of the rotating body  110  near the laser transceiver system  200  is screwed to the laser transceiver system  200  to drive the laser transceiver system  200  to rotate around the central axis. When the rotating body  110  rotates around its own central axis, the entire laser transceiver system  200  also rotates around the central axis of the rotating body  110 , and the path of the emitted laser emitted by the transmitting device of the laser transceiver system  200  changes accordingly. 
     In the threaded connection between the rotating body  110  and the laser transceiver system  200 , a screw hole may be provided in the rotating body  110 . A screw or bolt disposed in the laser transceiver system  200  extends from the laser transceiver system  200  into the screw hole in the rotating body  110  and is threadedly connected to the screw hole. Certainly, an outer thread may also be directly provided at an end of the rotating body  110 . For example, an outer thread is provided on a shaft body  112 , a connecting hole is provided on the laser transceiver system  200 , an inner thread is provided on an inner surface wall of the connecting hole, and the outer thread on the rotating body  110  cooperates with the inner thread in the connecting hole to implement a threaded connection between the rotating body  110  and the laser transceiver system  200 . The threaded connection between the rotating body  110  and the laser transceiver system  200  is not limited to the above situation, and will not be repeated herein. 
     After the rotating body  110  is disposed below the laser transceiver system  200 , the rotating body  110  and the laser transceiver system  200  may also be connected only by a shaft and a hole. For example, a connecting shaft is disposed at an upper end of the rotating body  110 , and a connecting hole is disposed at a lower end of the laser transceiver system  200 . The connecting shaft extends into the connecting hole to complete the detachable connection of the rotating body  110  and the laser transceiver system  200 , and horizontal cross sections of the connecting shaft and the connecting hole may not be circular, so that the rotating body  110  may drive the laser transceiver system  200  to rotate. Certainly, the foregoing connecting shaft may be disposed on the laser transceiver system  200 , and the foregoing connecting hole may be disposed on the rotating body  110 . 
     In some embodiments, the rotating system  100  may further include a base  500 . The base  500  may include a positioning column  510  extending in a direction parallel to the central axis of the rotating body  110 . The rotating body  110  includes a rotating cavity having an opening that is away from the laser transceiver system (that is, the opening of the rotating cavity  113  is disposed downward). The positioning column  510  extends into the rotating cavity  113  from the bottom up. After the positioning column  510  extends into the rotating cavity  113 , the positioning column  510  is located at the center of the rotating cavity  113 . 
     In some embodiments, the rotating system  100  may further include a driving motor  140 . The driving motor  140  is positioned on the positioning column  510  of the base  500 , and drives the rotating body  110  to rotate around the positioning column  510 . Specifically, the driving motor  140  may include a stator  141  and a rotor  142 . The stator  141  of the driving motor  140  is sleeved over the positioning column  510 . The rotor  142  of the driving motor  140  is connected to an inner peripheral wall of the rotating cavity  113 . When the driving motor  140  works, the rotor  142  rotates around the stator  141 , such that the rotating body  110  is driven by the rotor  142  to rotate around the positioning column  510  of the base  500 , and then the laser transceiver system  200  is driven by the rotating body  110  to rotate relative to the base  500 , and a purpose of changing the path of the laser emitted by the laser transceiver system  200  is finally achieved. 
     The LiDAR  20  may further include a first housing  300 . The first housing  300  may be the first housing  300  in the foregoing bearing mounting structure  700 . The first housing  300  defines an internal chamber  320 . The rotating system  100  is disposed in the internal chamber  320 , so that the first housing  300  protects the rotating system  100  well. The first housing  300  may include a rotating port  321  at an upper end thereof and a fixed port  322  at a lower end thereof. Both the rotating port  321  and the fixed port  322  penetrate the internal chamber  320  of the first housing  300 . The rotating system  100  is specifically disposed in the internal chamber  320  and near the fixed port  322 . The fixed port  322  of the first housing  300  may be fixedly connected to the base  500 . The laser transceiver system  200  originates a rotary motion at the rotating port  321  of the first housing  300 . 
     In an embodiment, the rotating body  110  may be positioned on the positioning column  510  of the base  500 , that is, the positioning column  510  provides the rotating body  110  with an upward bearing force. However, the positioning column  510  in the foregoing structure needs to provide the rotating body  110  with both a torque and a bearing force. Therefore, high requirements are imposed on mechanical properties of the positioning column  510 . However, because the positioning column  510  is disposed in the rotating cavity  113  of the rotating body  110 , and its size is limited, actual requirements can be hardly met. 
     In this embodiment, the first housing  300  may include a fixing structure  310  disposed in the internal chamber  320 . The rotating body  110  is positioned on the fixing structure  310  by a bearing  120 , so that the rotating body  110  can rotate relative to the fixing structure  310 . To be specific, the fixing structure  310  of the first housing  300  provides the rotating body  110  with an upward bearing force (when the rotating system  100  is disposed in another position of the laser transceiver system  200 , the first housing  300  provides the rotating body  110  with a bearing force in another direction). In addition, the first housing  300  and the rotating body  110  are connected by the bearing  120 , so that the rotating body  110  can further rotate relative to the fixing structure  310  while the fixing structure can provide the rotating body  110  with an upward bearing force. 
     When the rotating system  100  is disposed below the laser transceiver system  200 , the bearing  120  between the rotating body  110  and the fixing structure  310  needs to transmit a vertically upward bearing force. The bearing  120  may be a thrust bearing, and the thrust bearing is disposed at a lower end of the rotating body  110 . One side of the bearing abuts against the rotating body  110  and another side is fixed to the fixing structure  310  of the first housing  300 . The thrust bearing can provide the rotating body  110  with a great thrust while ensuring that the rotating body  110  can rotate relative to the fixing structure  310 . When the bearing  120  connected to the rotating body  110  is a thrust bearing, the thrust bearing may also be fixed to the base  500 . That is, after the positioning column  510  of the base  500  passes through the thrust bearing, an upper surface of the thrust bearing abuts against the rotating body  110 , and a lower surface thereof is positioned on the base  500 . Certainly, a form and specific structure of the bearing  120  depend on actual requirements. 
     In an embodiment, the rotating body  110  may be configured to carry the laser transceiver system  200 . That is, the rotating body  110  provides the laser transceiver system  200  with a vertically upward thrust. In this case, the bearing  120  between the rotating body  110  and the first housing  300  receives a combined gravity of both the rotating body  110  and the laser transceiver system  200 . Certainly, in another embodiment, another structure may be disposed on the first housing  300 , and the bearing  120  is connected between the structure and the laser transceiver system  200 , so that the first housing  300  can also produce relative rotation with the laser transceiver system  200  while carrying the gravity of the laser transceiver system  200 . 
     As described above, the rotating body  110  may include a driving body  111  and a shaft body  112  located on the driving body  111 ; the driving body  111  defines the foregoing rotating cavity  113  with an opening that faces the fixed port  322 ; the shaft body  112  is connected to one end of the driving body  111  away from the fixed port  322 ; and one end of the shaft body  112  away from the driving body  111  is threadedly connected to the laser transceiver system  200 . With this arrangement, an outer peripheral wall of the driving body  111  can be sleeved over the bearing  120 . Because a horizontal cross section of the driving body  111  is relatively large, a relatively large bearing  120  can be provided to increase an ultimate bearing capacity of the bearing  120 . In addition, the bearing  120  is disposed on the peripheral wall of the driving body  111  instead of being disposed in a vertical position of the rotating body  110  (that is, above or below the rotating body  110 ). This can reduce the space vertically occupied by the rotating system  100 , thereby reducing an overall vertical height of the LiDAR  10  (when the laser transceiver system  200  and the rotating system  100  are arranged vertically). 
     The base  500  may be integrated with the first housing  300 . However, in order to facilitate disassembly of the LiDAR  20 , in this embodiment, the base  500  is detachably connected to one end of the first housing  300  at the fixed port  322 . The positioning column  510  extends from the fixed port  322  toward the rotating port  321 . Specifically, the base  500  may be connected to the first housing  300  by using threaded fasteners. When the base  500  is connected to the fixed port  322  of the first housing  300 , the base  500  may cover the fixed port  322  of the first housing  300 , and the base  500  may also be used to carry the first housing  300 . That is, the base  500  provides the first housing  300  with a vertically upward bearing force. In another embodiment, alternatively, the first housing  300  may carry the base  500 . That is, the base  500  is connected to the fixed port  322  of the housing and then suspended, the bearing force of the base  500  is provided by the threaded connection between the base  500  and the first housing  300 , and the overall bearing force of the LiDAR  20  is provided by the first housing  300 . 
     In some embodiments, the fixing structure  310  of the first housing  300  may be a horizontally disposed ring-shaped bearing platform. However, in order to facilitate mounting and fixing of the rotating body  110  and the bearing  120 , in some embodiments, as shown in  FIG. 16 , the fixing structure  310  defines an accommodating chamber  311  that penetrates both ends. The bearing  120  may include an inner ring and an outer ring surrounding the inner ring. Balls or rollers may be provided between the outer ring and the inner ring. The inner ring of the bearing  120  is sleeved over an outer peripheral wall of the rotating body  110 . The outer ring is disposed in the accommodating chamber  311  of the fixing structure  310  and connected to an inner peripheral wall of the fixing structure  310 . 
     As shown in  FIGS. 12 and 13 , in order to facilitate positioning of the bearing  120 , a stepped structure may be disposed in the accommodating chamber  311  of the fixing structure  310 , and the bearing  120  is fixed to the stepped structure. The stepped structure can provide the outer ring of the bearing  120  with a vertically upward bearing force. In addition, in order to make positioning of the rotating body  110  more stable, two bearings  120  may be disposed in the accommodating chamber  311  of the fixing structure  310 , and the two bearings  120  are respectively sleeved over upper and lower ends of the outer peripheral wall of the driving body  111 . 
     The shaft body  112  of the rotating body  110  may extend upward from the first housing  300 , so that the shaft body  112  is detachably connected to the laser transceiver system  200 . However, in order to improve reliability of the connection between the laser transceiver system  200  and the rotating body  110 , in some embodiments, the lower end of the laser transceiver system  200  may be located in the internal chamber  320  and detachably connected to the shaft body  112  of the rotating body  110 . The other end of the laser transceiver system  200  protrudes upward from the internal chamber  320  through the rotating port  321 . The foregoing structure makes the connection between the laser transceiver system  200  and the shaft body  112  of the rotating body  110  covered by the first housing  300 , so that the connection between the two is not susceptible to failures caused by foreign matters. 
     When the lower end of the laser transceiver system  200  extends into the accommodating chamber  311  of the first housing  300 , a transmitting lens  220  for emitting the emitted laser and a receiving lens  230  for receiving the reflected laser in the laser transceiver system  200  are both located outside the internal chamber  320 , that is, the transmitting lens  220  and the receiving lens  230  are respectively disposed at the upper end of the laser transceiver system  200  that protrudes from the internal chamber  320 , to facilitate laser transmission and reception. 
     The laser transceiver system  200  may further include a supporting plate  210 . The supporting plate  210  is horizontally disposed in the internal chamber  320  of the first housing  300 . In addition, one side of the supporting plate  210  faces the fixed port  322 , and the other side thereof faces the rotating port  321 . The supporting plate  210  is disposed at a bottom end of the laser transceiver system  200 . The supporting plate  210  is detachably connected to the rotating system  100 , and is specifically connected to the shaft body  112  of the rotating system  100  by threaded fasteners. Both the transmitting device and the receiving device of the laser transceiver system  200  are disposed on an upper surface of the supporting plate  210 . 
     In order to protect internal components of the laser transceiver system  200 , the laser transceiver system  200  may further include an outer housing  240 . The outer housing  240  may be the inner housing  240  in the foregoing baffle fixing structure  600 . The outer housing  240  may be a protective housing located outside the internal components of the laser transceiver system  200 . The supporting plate  210  is connected to a lower end of the outer housing  240  and covers the lower end of the outer housing  240 . The transmitting device and the receiving device of the laser transceiver system  200  are both disposed in the space enclosed by the outer housing  240  and the supporting plate  210 . Because the space enclosed by the outer housing  240  and the supporting plate  210  does not include other components that block the laser path, the laser generated by the laser transmitting device can be emitted out of the outer housing  240  along a straight line, and the laser entering the outer housing  240  can also follow a straight line to arrive at the receiving device. 
     As shown in  FIGS. 11 to 16 , the LiDAR  20  may further include a second housing  400 . The second housing  400  may be the outer housing  400  in the foregoing baffle fixing structure  600 . The second housing  400  is connected to one end of the first housing  300  near the laser transceiver system  200 . The laser transceiver system  200  is completely located in a cavity enclosed by the second housing  400  and the first housing  300 . Specifically, the second housing  400  may be a spherical housing, and may also be made of a transparent material, so that the emitted laser generated by the transmitting device can travel outside the second housing  400 , and that the reflected laser received by the receiving device can enter the second housing  400 . 
     The emitted laser may pass through the transmitting lens  220  to travel outside the outer housing  240  and further pass through the second housing  400  to travel outside the second housing  400 . The reflected laser passes through the second housing  400  to enter the second housing  400  and further passes through the reflecting lens  230  (receiving lens  230 ) to enter the outer housing  240 . 
     In some embodiments, the laser transceiver system  200  may further include a circuit board  250 . The circuit board  250  is configured to process and transmit laser signals. The circuit board  250  is fixed to the supporting plate  210 . Specifically, the circuit board  250  may be disposed above the supporting plate  210  so that the inner housing  240  of the laser transceiver system  200  can protect the circuit board  25 . Alternatively, the circuit board  250  may be disposed below the supporting plate  210  to make full use of the space below the supporting plate  210 . In order to increase an area of the circuit board  250 , a hole may be provided in the circuit board  250  to allow the shaft body  112  of the rotating system  100  to pass through the hole of the circuit board  250 . In this way, the circuit board  250  may completely cover a lower surface of the supporting plate  210 . 
     The LiDAR  20  may further include a magnetic ring assembly. The magnetic ring assembly may include an inner magnetic ring  151  and an outer magnetic ring  152  arranged around the inner magnetic ring  151 . The inner magnetic ring  151  may be sleeved over the positioning column  510 , and the outer magnetic ring  152  is fixed in a position of the inner peripheral wall of the rotating body  110 . When the rotating body  110  rotates, the outer magnetic ring  152  rotates relative to the inner magnetic ring  151 . The outer magnetic ring  152  is electrically connected to the circuit board  250  of the laser transceiver system  200 , to transmit signals to the outer magnetic ring  152 . The outer magnetic ring  152  then transmits the received signals to the inner magnetic ring  151 , so that the signals of the laser transceiver system  200  can be smoothly transmitted to the outside of the LiDAR  20 . 
     It may be understood that for the laser transceiver system  200 , the laser transceiver system  200  includes the transmitting device and the receiving device, where the transmitting device includes a laser transmitting assembly and the transmitting lens, and the receiving device includes the receiving lens and a receiving assembly. A laser signal transmitted by the laser transmitting assembly first enters the transmitting lens through the space enclosed by the outer housing  240  and the supporting plate  210 , undergoes shaping by the transmitting lens, then enters the space enclosed by the second housing  400  and the outer housing  240 , and finally travels outside the second housing  400  to hit a target object. Therefore, for the laser transceiver system  200 , from a perspective of a propagation path of the laser signal, the laser signal first passes through the space defined by the outer housing  240 , and then passes through the second housing  400  to hit the target object. Therefore, in the following embodiment of the laser transceiver system, the second housing  400  is also referred to as the outer housing  400 , and the outer housing  240  is also referred to as the inner housing  240 . 
     In some embodiments, the LiDAR  20  may further include the foregoing baffle fixing structure  600 . Both the transmitting device and the receiving device of the laser transceiver system  200  are disposed in an accommodating chamber  242  of an inner housing  240  of the baffle fixing structure  600 . The emitted laser generated by the transmitting device passes through the inner housing  240  to travel outside the accommodating chamber  242 , and the reflected laser passes through the inner housing  240  to enter the accommodating chamber  242 . 
     The outer housing  400  is sleeved over the inner housing  240  and spaced apart from the inner housing  240 . The outer housing  400  is configured to protect the inner housing  240  or other components of the LiDAR  20 . When the transmitting device and the receiving device need to realize the function of rotation in the outer housing  400 , a gap needs to be reserved between the outer housing  400  and the inner housing  240 , and the gap is used to prevent position interference between the inner housing  240  and the outer housing  400  when the inner housing  240  rotates. 
     A first isolation portion  671  of a baffle  670  is disposed in the inner housing  240  and is configured to isolate the transmitting device from the receiving device. The first isolation portion  671  of the baffle  670  may divide the accommodating chamber  242  into two mutually isolated working chambers. The transmitting device and the receiving device are respectively arranged in the two working chambers. Therefore, the first isolation portion  671  of the baffle  670  may be configured to isolate the emitted laser from the incident light in the inner housing  240 . A second isolation portion  672  of the baffle  670  extends along an edge of the first isolation portion  671  to the space between the inner housing  240  and the outer housing  400 , and is configured to isolate the emitted laser from the reflected laser between the outer housing  400  and the inner housing  240 . 
     The transmitting lens  220  and the reflecting lens  230  (receiving lens  230 ) are both disposed at a working port  248  of the inner housing  240 . After the baffle  670  passes through an isolation slit  244 , the space between a recessed portion  246  of the inner housing  240  and the outer housing  400  is separated into two relatively independent parts to avoid mutual interference between the emitted laser and the reflected laser. The transmitting lens  220  and the reflecting lens  230  (receiving lens  230 ) are arranged on two opposite sides of the baffle  670  in a one-to-one correspondence. The transmitting lens  220  is disposed in one part of the working port  248 , and the reflecting lens  230  (receiving lens  230 ) is disposed in the other part. In this case, the transmitting lens  220  and the reflecting lens  230  (receiving lens  230 ) are respectively attached to two opposite surfaces of the baffle  670 , so that the laser passing through the transmitting lens  220  and the laser passing through the reflecting lens  230  (receiving lens  230 ) are unlikely to interfere with each other. When the working port  248  is configured based on the foregoing structure, the transmitting lens  220 , the baffle  670 , and the reflecting lens  230  (receiving lens  230 ) collectively fill the working port  248 . 
     In some embodiments, the LiDAR  20  may further include the foregoing bearing mounting structure  700 . 
     A driving body  111  of the bearing mounting structure  700  may be connected to the driving motor  140  of the LiDAR  20  and configured to obtain a driving force of the driving motor. Specifically, the driving body  111  may define a rotating cavity  113 . The driving motor  140  may be located in the rotating cavity  113  defined by the driving body  111 . The positioning column  510  extends into the rotating cavity  113  from the bottom up. After the positioning column  510  extends into the rotating cavity  113 , the positioning column  510  is located at the center of the rotating cavity  113 . The stator  141  of the driving motor  140  is sleeved over the positioning column  510 . The rotor  142  of the driving motor  140  is connected to the inner peripheral wall of the rotating cavity  113 . When the driving motor  140  works, the rotor  142  rotates around the stator  141 , such that the rotating body  110  is driven by the rotor  142  to rotate around the positioning column  510  of the base  500 . 
     The shaft body  112  is connected to an end of the driving body  111 , and an end of the shaft body  112  away from the driving body  111  is detachably connected to the laser transceiver system  200  and configured to transmit a torque to the laser transceiver system  200 . 
     One end of the first housing  300  away from the shaft body  112  may be detachably connected to the base  500 . Specifically, the base  500  may be connected to the first housing  300  by using threaded fasteners. The positioning column  510  extends toward the shaft body  112  from the end of the first housing  300  that is away from the shaft body  112 . The base  500  may cover a port of the first housing  300  away from the shaft body  112 , and the base  500  may also be used to carry the first housing  300 . That is, the base  500  provides the first housing  300  with a vertically upward bearing force. In another embodiment, alternatively, the first housing  300  may carry the base  500 . That is, the base  500  is connected to the port of the first housing  300  away from the shaft body  112  and then suspended, the bearing force of the base  500  is provided by the threaded connection between the base  500  and the first housing  300 , and the overall bearing force of the LiDAR  20  is provided by the first housing  300 . 
     It should be noted that the rotating system  100  may also include the foregoing angular displacement measurement device  800 , configured to measure a rotation angle of the laser transceiver system  200  relative to the base  500 . As described above, the angular displacement measurement device  800  may include a light emitting part  810  and a reflecting part  820 . The angular displacement measurement device  800  may be mounted in any position of the LiDAR. For example, the angular displacement measurement device  800  may be mounted between the rotating system  100  and the laser transceiver system  200 , or may be mounted between the base  500  and the rotating body  110 . 
     When the angular displacement measurement device  800  is mounted between the rotating system  100  and the laser transceiver system  200 , the light emitting part  810  may be indirectly connected to the rotating system  100 , and the reflecting part  820  may be directly or indirectly connected to an end of the laser transceiver system  200  near the rotating system  100 . Specifically, the light emitting part  810  may be directly or indirectly connected to the rotating port  321  at one end of the first housing  300  near the laser transceiver system  200 . Because the first housing  300  is fixedly connected to the base  500 , this is equivalent to indirectly connecting the light emitting part  810  to the rotating system  100  by using the first housing  300 , and specifically equivalent to indirectly connecting the light emitting part  810  to the base  500  by using the first housing  300 . The reflecting part  820  may be directly or indirectly connected to the lower surface of the supporting plate  210  of the laser transceiver system  200  near the rotating system  100 . Because the supporting plate  210  is fixedly connected to the shaft body  112  of the rotating body  110 , this is equivalent to indirectly connecting the reflecting part  820  to the rotating body  110  by using the supporting plate  210 . In this case, a function of the supporting plate  210  is consistent with a function of the foregoing rotating body  11 . In this case, the lower surface (that is, the end of the laser transceiver system  200  near the rotating system  100 ) of the supporting plate  210  near the rotating system  100  is an end wall  15  of the rotating body  11 . When the rotating system  100  drives the laser transceiver system  200  to rotate, the supporting plate  210  drives the reflecting part  820  to rotate relative to the first housing  300  and the light emitting part  810 , thereby measuring the rotation angle of the laser transceiver system  200  relative to the base  500 . 
     When the angular displacement measurement device  800  is mounted between the base  500  and the rotating body  110 , the light emitting part may be directly connected to the rotating system  100 , and the reflecting part  820  may be directly connected to one end of the rotating body  110  near the base  500 . Specifically, the light emitting part  810  may be directly connected to an end of the base  500  of the rotating system  100  near the first housing  300 . Because the first housing  300  is fixedly connected to the base  500 , this is equivalent to indirectly fixedly connecting the light emitting part  810  to the first housing  300 . Because the rotating body  110  is connected to the laser transceiver system  200 , this is equivalent to indirectly connecting the reflecting part  820  to the laser transceiver system  200 . In this case, one end of the rotating body  110  near the base  500  is the end wall  15  of the rotating body  11 . When the rotating system  100  drives the laser transceiver system  200  to rotate, the rotating body  110  drives the reflecting part  820  to rotate relative to the base  500  and the light emitting part  810 , thereby measuring the rotation angle of the laser transceiver system  200  relative to the base  500 . 
     In summary, after reading this detailed disclosure, those skilled in the art can understand that the foregoing detailed disclosure may be presented by way of example only, and may not be limiting. Although not explicitly stated herein, those skilled in the art will understand that the present application is intended to cover various changes, improvements and modifications of the embodiments. These changes, modifications, and improvements are intended to be made by the present disclosure and are within the spirit and scope of the exemplary embodiments of the present disclosure. 
     In addition, some of the terms in this application have been used to describe embodiments of the present disclosure. For example, “one embodiment,” “an embodiment,” and/or “some embodiments” means that a particular feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Therefore, it should be emphasized and understood that in various parts of the present disclosure, two or more references to “an embodiment,” “one embodiment,” or “an alternate embodiment” are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined as appropriate in one or more embodiments of the present disclosure. 
     It should be understood that in the description of the embodiments of the present disclosure, to assist in understanding a feature and for the purpose of simplifying the present disclosure, sometimes various features may be combined in a single embodiment, or drawings, description thereof. Alternatively, various features may be described in different embodiments of the present application. However, this is not to say that a combination of these features is necessary, and it is entirely possible for those skilled in the art to understand that a part of these features may be extracted as a separate embodiment. That is to say, the embodiments in the present application can also be understood as the integration of a plurality of secondary embodiments. It is also true that the content of each of the sub-embodiments may be less than all of the features of a single previously disclosed embodiment. 
     In some embodiments, numbers expressing quantities or properties used to describe or define the embodiments of the present application should be understood as being modified by the terms “about,” “approximate,” or “substantially” in some instances. For example, “about,” “approximately,” or “substantially” may mean a ±20% change in the described value or less, unless otherwise stated. Accordingly, in some embodiments, the numerical parameters set forth in the written description and the appended claims are approximations, which may vary depending upon the desired properties sought to be obtained in a particular embodiment. In some embodiments, numerical parameters should be interpreted in accordance with the value of the parameters and by applying ordinary rounding techniques. Although a number of embodiments of the present application provide a broad range of numerical ranges and parameters that are approximations, the values in the specific examples are as accurate as possible. 
     Each of the patents, patent applications, patent application publications, and other materials, such as articles, books, instructions, publications, documents, products, etc., cited herein are hereby incorporated by reference, which are applicable to all contents used for all purposes, except for any history of prosecution documents associated therewith, any identical, or any identical prosecution document history, which may be inconsistent or conflicting with this document, or any such subject matter that may have a restrictive effect on the broadest scope of the claims associated with this document now or later. For example, if there is any inconsistent or conflicting in descriptions, definitions, and/or use of a term associated with this document and descriptions, definitions, and/or use of the term associated with any materials, the term in this document shall prevail. 
     Finally, it should be understood that the embodiments of the application disclosed herein are merely described to illustrate the principles of the embodiments of the application. Other modified embodiments are also within the scope of this application. Therefore, the embodiments disclosed herein are by way of example only and not limitations. Those skilled in the art can adopt alternative configurations to implement the invention in this application in accordance with the embodiments of the present application. Therefore, the embodiments of the present application are not limited to those embodiments that have been precisely described in this disclosure.