Three-dimensional laser radar system based on one-dimensional linear array scanning and cam forming method

Abstract

This invention discloses a three-dimensional lidar system based on one-dimensional linear array scanning and a cam forming method. The system includes: a transceiver module for transmitting and receiving linear array laser beams; and a scanning module including a mirror, a driving component, and a cam mechanism. The mirror reflects the linear array laser beams, and the cam mechanism includes a cam body and a rocker arm. The driving component is connected to the cam body and drives it to rotate at a constant speed. The mirror is connected to the rocker arm, and the rocker arm is connected to the cam body. The cam body rotates at a constant speed and drives the mirror to reciprocate at a constant speed within a preset angle, thereby changing the angle at which the transceiver module transmits and receives the linear array laser beams in the horizontal direction. The cam forming method is applied to the aforementioned three-dimensional lidar system based on one-dimensional linear array scanning. The three-dimensional lidar system and cam forming method proposed in this invention enable the lidar system to simultaneously satisfy the requirements of a large field of view in the vertical direction and low system height and complexity.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, and in particular to a three-dimensional lidar system based on one-dimensional linear array scanning and a method for forming a cam. Background Technology

[0002] With the rapid development of autonomous driving, robot navigation, and 3D perception technologies, 3D LiDAR based on one-dimensional linear array scanning is gradually becoming a mainstream technology. A conventional one-dimensional linear array scanning 3D LiDAR achieves scanning through mirror rotation, but such systems cannot simultaneously achieve a large vertical field of view while maintaining a low system height. The typical vertical field of view for this type of LiDAR is 20°-30°, while the typical vertical field of view in this invention is 75°-80°. Another type of one-dimensional linear array scanning 3D LiDAR achieves 360° scanning by rotating the transceiver module, but this type of system requires wireless power supply and wireless communication, resulting in high system complexity. Furthermore, multi-line LiDAR systems handle large amounts of data, placing high demands on wireless communication bandwidth, further increasing system complexity.

[0003] Therefore, how to make a 3D lidar system have a large field of view in the vertical direction while having a low system height and low system complexity has become a technical problem that urgently needs to be solved in the field of lidar. Summary of the Invention

[0004] The main objective of this invention is to provide a three-dimensional lidar system based on one-dimensional linear array scanning, which aims to solve the technical problem that current lidar systems cannot simultaneously satisfy the requirements of having a large field of view in the vertical direction and low system height and complexity.

[0005] To achieve the above objectives, the present invention proposes a three-dimensional lidar system based on one-dimensional linear array scanning, comprising:

[0006] Transceiver module for transmitting and receiving linear laser beams; and The scanning module includes a tilting mirror, a driving component, and a cam mechanism. The tilting mirror reflects the linear laser beam. The cam mechanism is a cam-rocker mechanism and includes a cam body and a rocker arm. The driving component is connected to the cam body and drives the cam body to rotate at a constant speed. The tilting mirror is connected to the rocker arm, and the rocker arm is connected to the cam body. The cam body rotates at a constant speed and drives the tilting mirror to oscillate back and forth at a constant speed within a preset angle through the rocker arm, thereby changing the angle at which the transceiver module transmits and receives the linear laser beam in the horizontal direction.

[0007] In one embodiment, the cam body is provided with a guide portion, and the end of the rocker arm away from the rocker mirror moves along the guide portion.

[0008] In one embodiment, the guide portion is configured as a groove, and one end of the rocker arm is provided with a roller, which is movably disposed in the groove and contacts the inner wall of the groove.

[0009] In one embodiment, the guide portion is arranged around the rotation center of the cam body, and the rocker arm has a first swing limit position and a second swing limit position, which are symmetrically arranged. At the first swing limit position or the second swing limit position, the connection point between the rocker arm and the guide portion is M, and the line connecting point M and the rotation center of the cam is the swing axis of the cam body. When the rocker arm moves from the first swing limit position to the second swing limit position or from the second swing limit position to the first swing limit position, the swing angle of the rocker arm and the rotation angle of the swing axis are a linear function relationship.

[0010] In one embodiment, the guide portion further includes a smooth transition section, which corresponds to the first swing limit position and the second swing limit position.

[0011] In one embodiment, the three-dimensional lidar system further includes a support base with a rotating shaft. The tilting mirror is rotatably connected to the rotating shaft, and the driving component is fixedly mounted on the support base. The output shaft of the driving component is connected to the cam body.

[0012] In one embodiment, the three-dimensional lidar system further includes a motherboard electrically connected to the driving component. The transceiver module includes a transmitting module, a receiving module, and an optical board. The transmitting module and the receiving module are respectively disposed on the optical board, which is electrically connected to the motherboard. The transmitting module is used to emit a linear array laser beam. The linear array laser beam is reflected by the tilting mirror and directed toward the target object. The target object reflects the linear array laser beam and forms an echo beam. The receiving module is used to receive the echo beam reflected by the tilting mirror.

[0013] This invention also proposes a cam forming method, applied to a three-dimensional lidar system based on one-dimensional linear array scanning as described above, wherein the forming method includes: Define the motion target of the cam body and obtain the preset swing angle range of the rocker arm; A connection angle is reserved at the extreme position of the swing angle; A mathematical model of the cam body profile is established based on the rotation angle of the cam body and the swing angle of the rocker arm. The theoretical profile point set of the cam body is obtained based on the mathematical model of the cam body profile. Output the profile of the cam body.

[0014] In one embodiment, the swinging law of the rocker arm includes uniform swinging and smooth transition, and the cam body reserves connection angles at both ends of the uniform swinging angle range of the rocker arm: φ2~φ3, φ4~φ1. During the process of the cam body rotating uniformly around the central axis of the cam body for one revolution, the rocker arm realizes one reciprocating swing within the preset swinging angle range. When the rotation angle φ of the cam body is in the range of φ1~φ2, φ3~φ4, the swinging angle α of the rocker arm and the rotation angle φ of the cam body have a linear function relationship. The contour of the cam body corresponds to the uniform swinging segment of the rocker arm, and the contour of the cam body corresponds to the smooth transition segment of the rocker arm.

[0015] In one embodiment, before outputting the profile of the cam body, the pressure angle between the rocker arm and the cam body is checked and optimized, and the profile of the cam body is optimized through multiple iterations.

[0016] This invention employs a tilting mirror as the core optical element of the scanning module. Its reciprocating oscillation achieves horizontal scanning, avoiding the need for a fully rotating transceiver module or complex optical path folding structures. This reduces the path length of the transmitted and received rays within the module, thereby decreasing the module's vertical height. Furthermore, since the transceiver module is fixed and uses a one-dimensional linear laser array, the vertical field of view is determined by the laser's emission angle and receiving field of view, easily achieving a large vertical field of view without being constrained by the scanning structure. Therefore, the overall system height is reduced. This solution also simplifies electrical and communication design by fixing the transceiver module and driving only the tilting mirror for scanning, allowing direct connection of power and communication lines. The scanning module uses a cam body in conjunction with a swing arm to convert the uniform rotation of the driving component into the uniform reciprocating oscillation of the tilting mirror. This method is simple, reliable, low-cost, and facilitates precise angle control and repeatable positioning. Compared to a drive motor directly driving the tilting mirror, this solution uses a common motor connected to a cam mechanism to achieve oscillation, eliminating the need for motor reciprocating oscillation and reducing overall system complexity and cost. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of a three-dimensional lidar system based on one-dimensional linear array scanning provided by the present invention; Figure 2 An exploded structural diagram of an embodiment of a three-dimensional lidar system based on one-dimensional linear array scanning provided by the present invention; Figure 3 An exploded view of the transceiver module of a three-dimensional lidar system based on one-dimensional linear array scanning, provided by the present invention. Figure 4 An exploded view of the scanning module of a three-dimensional lidar system based on one-dimensional linear array scanning, provided by the present invention; Figure 5 A schematic diagram of the working logic of a three-dimensional lidar system based on one-dimensional linear array scanning provided by the present invention; Figure 6 This is a top view of the scanning limit position of an embodiment of a three-dimensional lidar system based on one-dimensional linear array scanning provided by the present invention; Figure 7 This invention provides a cam forming method and an analytical schematic diagram; Figure 8 This is a schematic diagram of a lidar system structure based on a rotating mirror scheme in the prior art; Figure 9 for Figure 8 Schematic diagram of the scanning limit position of the lidar system in China; Figure 10 This is a schematic diagram of a 360° lidar system in the prior art.

[0019] Explanation of icon numbers: 1. Transceiver module; 11. Transmitter module; 111. Light source; 112. Transmitting optical element; 12. Receiver module; 121. Photoelectric sensor; 122. Receiving optical element; 13. Optical plate; 2. Scanning module; 21. Drive component; 22. Swing mirror; 23. Cam mechanism; 231. Cam body; 2311. Guide part; 232. Swing rod; 233. Roller; 3. Motherboard; 4. Support base; 41. Rotating shaft.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] In existing technologies, a conventional one-dimensional linear array scanning 3D LiDAR achieves scanning by rotating a mirror. However, this type of LiDAR system cannot achieve a large field of view in the vertical direction while maintaining a low system height. Another one-dimensional linear array scanning 3D LiDAR achieves 360° scanning by rotating a transceiver module, but this type of LiDAR system requires wireless power supply and wireless communication, resulting in high system complexity. Furthermore, multi-line LiDAR systems have large data volumes and high bandwidth requirements, further increasing system complexity. Therefore, how to enable a 3D LiDAR system to have a large field of view in the vertical direction while maintaining a low system height and low system complexity has become a pressing technical problem to be solved in the field of LiDAR.

[0025] refer to Figures 8 to 10 As shown, Figure 8 This is a schematic diagram of a lidar system based on a rotating mirror scheme. The lidar system mainly includes a transceiver module 1 and a scanning module 0. The transceiver module 1 includes a transmitting module 11 and a receiving module 12 for transmitting and receiving laser beams. The scanning module 0 includes a drive motor 01 and a rotating mirror 02. The drive motor 01 drives the rotating mirror 02 to rotate, and the rotating mirror 02 changes the horizontal angle of the transmitted and received beams by reflecting the laser beam, thereby achieving one-dimensional scanning.

[0026] Figure 9 yes Figure 8 A schematic diagram of the scanning limit position of a laser radar system. Assume the field of view of the transmitting module in the vertical direction is FOV_V. Figure 9 In this context, h is the height of the rotating mirror 02, s is the baseline between the transmitting module 11 and the receiving module 12, point A is the starting point of the field of view of the emitted beam, l is the length of the line segment of the intersection area between the emitted beam and the edge of the rotating mirror at the extreme position, point P is the center point of the aforementioned line segment l, and the distance from point A to point P is |AP|, therefore l = 2. tan(FOV_V / 2) |AP|. For example... Figure 9 As shown, to ensure the lidar system can scan the target object across the entire field of view, the height h of the rotating mirror 02 must at least satisfy: h ≥ l + s. Since the |AP| value changes continuously during scanning, and is maximum at the right extreme position, the height h of the rotating mirror 02 needs to be designed according to the |AP| value at the right extreme position, resulting in a relatively large height h. Simultaneously, the larger the vertical field of view FOV_V, the larger l becomes, leading to a larger height h of the rotating mirror 02. Furthermore, since the rotating mirror 02 needs to rotate 360°, the transceiver module 1 is typically placed outside the rotation area of ​​the rotating mirror 02 to avoid interference between the transceiver module 1 and the rotating mirror 02. Meanwhile, the drive motor 01 can be placed coaxially inside the rotating mirror 02, and the overall height of the lidar system is approximately the height h of the rotating mirror with the built-in drive motor, further increasing the overall height of the system. Alternatively, the drive motor 01 can be placed below the rotating mirror 02, and the overall height of the lidar system is approximately the height h of the rotating mirror + the thickness of the drive motor + clearance, which also further increases the overall height of the system. Therefore, the typical vertical field of view of the transceiver module in the rotating mirror scheme is 20°-30°, which makes it difficult to balance a large vertical field of view with a relatively low system height.

[0027] Figure 10 This is a schematic diagram of a 360° lidar system. The system mainly includes a transceiver module 09, an upper circuit board 04, a brushless DC motor 05, an optical communication module 06, a wireless power supply module 07, and a lower circuit board 08. The transceiver module 09 and the upper circuit board 04 are used to transmit and receive laser beams. The transceiver module 09 and the upper circuit board 04 are connected to the rotor of the brushless DC motor 05, and the rotor drives the transceiver module 09 and the upper circuit board 04 to rotate, achieving one-dimensional scanning. The power supply and data interface of this lidar system is located on the lower circuit board 08, which, along with the brushless DC motor 05, is fixed. The wireless power supply module 07 is used to supply power from the fixed components to the rotating components, and the optical communication module 06 is used to enable data communication between the fixed and rotating components. Therefore, this type of lidar system requires both wireless power supply and wireless communication, resulting in high system complexity. Furthermore, multi-line lidar systems handle large amounts of data and require high communication bandwidth, further increasing system complexity.

[0028] This invention proposes a three-dimensional lidar system based on one-dimensional linear array scanning.

[0029] Please see Figures 1 to 7 As shown, in one embodiment of the present invention, the three-dimensional lidar system based on one-dimensional linear array scanning includes: a transceiver module 1 and a scanning module. The transceiver module 1 is used to transmit and receive linear array laser beams. The scanning module includes a swing mirror 22, a driving component 21, and a cam mechanism 23. The swing mirror 22 is used to reflect the linear array laser beam. The cam mechanism 23 is a cam-rocker mechanism and includes a rocker arm 232 and a cam body 231. The driving component 21 is connected to the cam body 231 and drives the cam body 231 to rotate at a constant speed. The swing mirror 22 is connected to the rocker arm 232, and the rocker arm 232 is connected to the cam body 231. The cam body 231 rotates at a constant speed and drives the swing mirror 22 to swing back and forth at a constant speed within a preset angle through the rocker arm 232, thereby changing the angle of the transceiver module 1 transmitting and receiving the linear array laser beam in the horizontal direction.

[0030] Please see Figure 1 As shown, in the specific implementation process, the transceiver module 1 is fixedly installed on the system's support base (e.g., Figure 1 The transceiver module 1, located on a housing (not shown), is used to transmit and receive linear array laser beams. Optionally, the transceiver module 1 in this invention has a large field of view in the vertical direction, typically 75°-80°. In this embodiment, since the transceiver module is fixed, it can be powered by a fixed device or circuit board, eliminating the need for wireless power supply. Furthermore, the transceiver module and the motherboard can communicate directly via a wired method such as a flexible printed circuit board (FPC), eliminating the need for high-bandwidth wireless communication.

[0031] The scanning module is used to change the pointing angle of the linear laser beam in the horizontal direction to achieve horizontal scanning. The tilting mirror 22 is preferably a plane mirror, which is oscillatingly mounted on a support or housing via a pivot. The tilting mirror 22 is positioned in the optical path of the linear laser beam emitted by the transceiver module 1 to reflect the beam to the external detection area. The driving component 21, such as a brushless DC motor, stepper motor, or servo motor, has its output shaft connected to the cam body 231. In this embodiment, the driving component 21 preferably drives the cam body 231 to rotate at a constant speed.

[0032] Please see Figures 1 to 4As shown, the cam body 231 is an end-face cam with a specially designed profile curve. A rocker arm 232 is fixedly connected to the mirror 22. One end of the rocker arm 232 is fixedly connected to the rotating shaft of the mirror 22 or to the mirror frame of the mirror 22, while the other end is equipped with a driven component, such as a bearing or slider. This driven component maintains contact with the profile surface of the cam body 231. When the driving component 21 drives the cam body 231 to rotate at a constant speed, the change in the radius of the cam body profile pushes or releases the driven component in contact with it, thereby converting the rotational motion of the cam into the reciprocating oscillation of the mirror 22 around the rotating shaft via the rocker arm 232. By precisely designing the profile curve of the cam body 231, the oscillation angular displacement of the mirror 22 can be made linearly related to time, thus enabling the mirror 22 to reciprocate at a constant speed within a preset angle range.

[0033] Please see Figure 5 As shown, the vertical linear laser beam emitted from transceiver module 1 is reflected by the uniformly oscillating mirror 22, forming a uniformly scanning linear laser beam in the horizontal direction. The linear laser beam is emitted to the target object, and the echo beam from the target object is reflected by the mirror 22 and received by transceiver module 1. By measuring the time of flight (ToF) and combining it with the real-time angle of the mirror 22, the system can calculate the three-dimensional spatial coordinates of each laser point and output point cloud information.

[0034] Please see Figure 6 As shown, point A is the starting point of the field of view of the emitted beam, and point P is the center point of the line segment where the emitted beam intersects with the tilting mirror 22 at the extreme position. When the transceiver module 1 of the lidar system has a large field of view in the vertical direction, the system height largely depends on the height of the tilting mirror 22, which in turn depends on the maximum value of |AP| during the scanning process. In this embodiment, on the one hand, the lidar system uses the tilting mirror 22 as a reflector, and the center of the tilt is close to the back of the tilting mirror 22. Therefore, the reflection point P changes little during the scanning process, i.e., the value of |AP| changes little. On the other hand, the driving component 21, such as the driving motor, is located on the back of the tilting mirror 22 and drives the tilting mirror 22 through a cam mechanism. The horizontal dimension of the tilting mirror 22 can be designed to be small, making the tilting area of ​​the tilting mirror 22 smaller. This allows the transceiver module to be placed closer to the tilting mirror 22, i.e., the distance between point A and point P can be designed to be smaller, resulting in a smaller value of |AP|. Therefore, the lidar system provided in this embodiment has a much smaller |AP| value than the rotating mirror scheme during the scanning process, and the change is not significant. It can take into account both a large field of view in the vertical direction and a relatively low system height.

[0035] Furthermore, this embodiment designs a scanning module based on the cam body 231 and the swing arm 232. The driving component 21 uses a drive motor to convert the uniform rotation of the drive motor into uniform reciprocating oscillation of the swing arm 232 within a preset swing angle range. Therefore, on the one hand, in this embodiment, the drive motor can be a conventional motor and control scheme, such as a low-cost DC brushed motor, which can be directly driven without the need for complex structures and controls such as stepper motors or servo motors. On the other hand, if the swing mirror 22 is directly driven by the drive motor, the drive motor usually needs to frequently change direction to achieve the swing of the swing mirror 22, resulting in high motor control complexity. In this embodiment, the drive motor adopts a uniform speed driving method, using a scheme with lower motor control complexity, and achieving uniform reciprocating oscillation of the swing arm 232 within a preset swing angle range at a lower cost.

[0036] Please see Figure 4 As shown, in one embodiment, the cam body 231 is provided with a guide portion 2311, and the end of the rocker arm 232 that is away from the rocker mirror 22 moves along the guide portion 2311.

[0037] In practical implementation, the guide portion 2311 can be a continuous, closed groove or guide rail, and its trajectory is precisely designed according to the uniform reciprocating oscillation law of the required swing mirror 22. Correspondingly, the end of the swing rod 232 opposite to the swing mirror 22 is provided with a driven head that cooperates with the guide portion 2311, such as a roller 233 or a slider embedded in the groove, which is constrained to move within the guide portion 2311. When the driving component 21 drives the cam body 231 to rotate at a uniform speed, the driven head is restricted to move within the trajectory of the guide portion 2311. The guide portion 2311 provides a clear motion path constraint for the end of the swing rod 232, reduces the backlash and uncertainty in the transmission chain, makes the angle positioning of the swing mirror 22 more accurate, and helps to improve the spatial accuracy of point cloud information.

[0038] Please continue reading. Figure 4 As shown, in one embodiment, the guide portion 2311 is configured as a groove, and one end of the rocker arm 232 is provided with a roller 233, which is movably disposed in the groove and contacts the inner wall of the groove.

[0039] Optionally, the guide portion 2311 on the cam body 231 is specifically configured as a precision-machined annular groove. The trajectory of the groove's centerline is designed according to the horizontal uniform scanning law required by the swing mirror 22. Correspondingly, a roller 233, such as a miniature deep groove ball bearing or needle roller bearing, is fixedly installed at the end of the swing arm 232 away from the swing mirror 22. The circumferential surface of the roller 233 is embedded and accommodated in the annular groove, so that the outer edge of the roller 233 maintains contact with or can switch contact with the inner walls on both sides of the groove. When the cam body 231 rotates at a uniform speed, the inner walls on both sides of the groove act alternately or synergistically on the roller 233, directly and without slippage converting the rotational force into a force that drives the swing arm 232 to move linearly or arcuately. The physical boundary of the groove ensures that the movement path of the roller 233 is uniquely and rigidly defined, resulting in extremely high transmission accuracy and repeatability. Since the roller 233 may contact both sides of the inner wall of the groove, it can obtain a direct force transmission path during both forward drive and reverse return, effectively eliminating the backlash that may occur due to single-sided contact in traditional cam follower mechanisms. The movement of the roller 233 within the groove is rolling friction, which, compared to the sliding friction of sliders or flat-bottomed followers, has lower frictional resistance, lower wear, and smoother operation. This not only reduces the load and power consumption of the drive component 21 but also extends the mechanical life of the entire scanning module, improving the long-term reliability of the product. Designing the guide portion 2311 as a groove, completely accommodating the transmission component (roller 233) within the cam body contour, makes the entire transmission pair structure very compact, which helps to further reduce the radial dimension of the scanning module and achieve a more miniaturized LiDAR design.

[0040] Please continue reading. Figure 6 and Figure 7 As shown, in one embodiment, the guide portion 2311 is arranged around the rotation center of the cam body 231, and the rocker arm 232 has a first swing limit position and a second swing limit position, which are symmetrically arranged. At the first swing limit position or the second swing limit position, the connection point between the rocker arm 232 and the guide portion 2311 is M. The line connecting point M and the rotation center of the cam is the swing axis of the cam body 231. When the rocker arm 232 moves from the first swing limit position to the second swing limit position or from the second swing limit position to the first swing limit position, the swing angle of the rocker arm 232 and the rotation angle of the swing axis are a linear function relationship.

[0041] In a specific implementation, when the rocker arm 232 is at the first swing limit position A (the same applies to position B), the center point of the roller 233 (i.e., the connection point between the rocker arm 232 and the guide part 2311) is located at point M. Connecting point M to the rotation center O1 of the cam body 231, the resulting straight line O1M is defined as a specific reference axis for the cam body 231, which can be the swing initiation reference axis. During the process of the driving component 21 driving the cam body 231 to rotate at a constant angular velocity ω, when the cam body 231 drives the rocker arm 232 from position A to position B, or from position B to position A, the real-time swing angle θ (the angle relative to its center zero position) of the rocker arm 232 and the real-time rotation angle φ (the angle relative to the swing initiation reference axis O1M) of the cam body 231 satisfy a linear function relationship. That is: θ = k φ+b (where k and b are constants).

[0042] The cam rotates at a constant speed, while the oscillation of the rocker arm 232 is linearly proportional to the cam's rotation angle. Therefore, the angular velocity of the rocker arm 232 is dθ / dt = k dφ / dt = kω is also a constant, proving from a kinematic perspective that the oscillation of the pendulum mirror 22 is a uniform motion with a constant angular velocity. Within the scanning cycle of the lidar, the sampling frequency of the laser is fixed. Since the angular velocity of the pendulum mirror 22 is constant, the increment of the angle through which the laser beam rotates in the horizontal direction is the same within the same sampling time interval.

[0043] Please continue reading. Figure 7 As shown, the guide portion 2311 further includes a smooth transition section, which corresponds to the first swing limit position and the second swing limit position.

[0044] Two smooth transition sections are provided on the annular trajectory of the guide section 2311. These two smooth transition sections correspond spatially to the first swing limit position A and the second swing limit position B of the rocker arm 232, respectively. That is, when the roller 233 moves to these two positions, it is within the range of the smooth transition section. This smooth transition section refers to a segment on the groove contour curve of the guide section 2311, whose radius of curvature is continuous and gradually changes. Its purpose is to achieve a smooth and shock-free transition of the rocker arm 232 from forward drive to reverse drive. The smooth transition section is designed so that the velocity direction of the center of the roller 233 changes continuously and smoothly within the transition section, gradually decreasing to zero and then gradually increasing in the opposite direction, avoiding sudden velocity changes and thus eliminating rigid impact.

[0045] Please continue reading. Figure 1As shown, in one embodiment, the three-dimensional lidar system further includes a support base 4, the support base 4 is provided with a rotating shaft 41, the swing mirror 22 is rotatably connected to the rotating shaft 41, the drive component 21 is fixedly provided on the support base 4, and the output shaft of the drive component 21 is connected to the cam body 231.

[0046] In practical implementation, the support base 4 serves as the basic load-bearing structure and installation benchmark for the entire scanning module. It is typically precision-machined from a high-rigidity, low-thermal-expansion-coefficient material (such as aluminum alloy or engineering plastics). A rotating shaft 41 is provided on the support base 4. This shaft 41 can be mounted on the support using precision bearings (such as miniature ball bearings). Its axis position is precisely designed and machined, defining the rotation center of the swing mirror 22. The swing mirror 22 (via its frame or rotating shaft) is rotatably connected to the rotating shaft 41. Understandably, the swing mirror 22 oscillates back and forth around the rotating shaft 41 provided by the support base 4, thus directly integrating the rotational support structure of the swing mirror 22 onto the support base 4. This ensures the stability and rigidity of the swing center, preventing mirror jitter or optical axis drift caused by the flexibility of the support structure.

[0047] The drive component 21 (such as a motor) is fixedly mounted on the support base 4, typically by screws tightening between the mounting holes on the motor flange and the corresponding interface on the support base 4. The output shaft of the drive component 21 is directly connected to the cam body 231 or via a coupling. Since both the drive component 21 and the rotating shaft 41 are mounted on the same support base 4, their relative positional relationship is determined and locked during assembly, ensuring a stable geometric relationship between the rotation center of the cam body 231 and the oscillating system of the mirror 22.

[0048] Please continue reading. Figures 1 to 3 As shown, in one embodiment, the three-dimensional lidar system further includes a motherboard 3, which is electrically connected to a drive component 21. The transceiver module 1 includes a transmitting module 11, a receiving module 12, and an optical board 13. The transmitting module and the receiving module are respectively disposed on the optical board 13, which is electrically connected to the motherboard 3. The transmitting module 11 is used to transmit a linear array laser beam. The linear array laser beam is reflected by a tilting mirror 22 and then directed toward the target object. The target object reflects the linear array laser beam and forms an echo beam. The receiving module 12 is used to receive the echo beam reflected by the tilting mirror 22.

[0049] In practical implementation, the motherboard 3 serves as the control and data processing center of the entire system, typically integrating a main control MCU / FPGA, power management unit, motor drive circuit, and high-speed data interface. The motherboard 3 is electrically connected to the drive component 21, providing power and outputting precise control signals to control its operation at a preset constant speed, thereby driving the cam body 231 to rotate at a uniform speed. The transceiver module 1 is a highly integrated optoelectronic system, mainly comprising a transmitting module 11, a receiving module 12, and an optical board 13. The transmitting module 11 and the receiving module 12 are mounted on the optical board 13 with high-precision positioning, ensuring that their optical axes are parallel or have a fixed spatial relationship.

[0050] Please continue reading. Figure 3 As shown, in the transceiver module 1, the transmitting module 11 may include a light source 111, a transmitting optical element 112, or other transmitting schemes, which are not limited here. The light source 111 is a laser light source 111, which can be a VCSEL (Vertical-Cavity Surface-Emitting Laser), EEL (Edge-Emitting Laser), HCSEL (Horizontal-Cavity Surface-Emitting Laser), etc., and is not limited here. The transmitting optical element 112 is positioned in the light-emitting direction of the light source 111 and is used to shape the laser beam emitted from the light source 111 before projecting the linear array laser beam onto the target object. The receiving module 12 may include a photoelectric sensor 121, a receiving optical element 122, etc., or other receiving schemes, which are not limited here. The photoelectric sensor 121 can be a linear array SPAD-SOC sensor, an area array SPAD-SOC sensor, a linear array SiPM sensor, etc., and is not limited here. After the target object reflects the beam, the echo beam is transmitted to the photoelectric sensor 121 through the receiving optical element 122, generating Time-of-Flight (ToF) data. The optical plate 13 serves as a support for the transmitting module 11 and the receiving module 12, and also provides peripheral circuits for power supply, driving, signal transmission and processing for the transmitting module 11 and the receiving module 12. The transceiver module 1 provided in this embodiment has a large field of view in the vertical direction.

[0051] Please continue reading. Figure 4As shown, in the scanning module, the drive motor provides power to the swing mirror 22. The drive motor can be a DC brushed motor or a DC brushless motor. The cam body 231 is responsible for transmitting the rotation of the drive motor to the swing mirror 22, causing the swing mirror 22 to swing back and forth at a uniform speed and reflect the linear array laser beam. The swing mirror 22 is fixed on the swing rod 232 and moves synchronously with the swing rod 232. The swing rod 232 is mounted on the support base 4 through a hole-shaft fit. The drive motor is fixed on the support base 4, and the cam body 231 is connected to the central shaft of the drive motor through a key connection or other connection methods. It should be noted that the cam body 231 provided in this embodiment not only converts the rotation of the drive motor into the reciprocating swing of the swing mirror 22 within a preset swing angle range, but also, during the uniform rotation of the drive motor, the swing mirror 22 can optionally make both the forward and reverse swings within the preset swing angle range uniform in speed.

[0052] Please continue reading. Figure 1 As shown, the optical board 13 is electrically connected to the main board 3. The main board 3 provides trigger signals and drive current to the transmitting module 11 to control its laser pulse emission. Simultaneously, the receiving module 12 amplifies the received weak photoelectric signal at the front end and transmits it to the main board 3 for processing via the circuitry on the optical board 13. Under the control of the main board 3, the transmitting module 11 emits a linear laser beam, which first strikes a swing mirror 22 at a specific swing angle. After reflection by the swing mirror 22, the direction of the linear laser beam is changed, directing it towards a target object in external space. Because the swing mirror 22 swings at a uniform speed, the laser beam achieves horizontal scanning. The target object reflects some of the laser energy, forming an echo beam that again illuminates the swing mirror 22 at the same position. The swing mirror 22 reflects the echo beam to the fixed receiving module 12, which converts the optical signal into an electrical signal. By integrating the transmitting and receiving modules 12 onto the same optical board 13, the positional and thermal stability of both are ensured. The electrical connection between the optical board 13 and the main board 3 forms a clear and reliable signal transmission path, which improves electromagnetic compatibility and signal quality.

[0053] Please continue reading. Figure 5As shown, this invention provides a schematic diagram of the working logic of a one-dimensional linear array scanning lidar system. The motherboard 3 controls the drive motor of the scanning module to rotate at a constant speed. Simultaneously, the motherboard 3 can selectively acquire the current rotation angle of the drive motor through a photoelectric encoder, Hall effect sensor, or other means. Preferably, the motherboard 3 employs closed-loop control, which can make the rotation speed of the drive motor more stable. The motherboard 3 can trigger a measurement signal based on the horizontal rotation angle value of the drive motor, or it can trigger a measurement signal at fixed time intervals, reading the current rotation angle value of the drive motor simultaneously with the trigger. The motherboard 3 sends the measurement signal to the optical board 13 of the transceiver module 1. The optical board 13 drives the transmitting module 11 to start measurement. The light source 111 generates a narrow pulse laser. The laser beam passes through the transmitting optical element 112 and is emitted to the oscillating mirror 22 of the scanning module, and then reflected by the oscillating mirror 22 towards the target object. After being reflected by the target object, the echo beam is reflected again by the oscillating mirror 22 to the receiving module 12 of the transceiver module 1. Finally, after receiving the signal, the photoelectric sensor 121 of the receiving module 12 generates ToF data and outputs it to the main board 3 through the optical board 13. The main board 3 can output point cloud information based on the ToF data and the angle information.

[0054] Please continue reading. Figure 6 As shown, when the scanning module is in its initial state, for example... Figure 6 When the rocker arm 232 reaches the right limit position of the preset swing angle range shown in (b), the drive motor rotates at a constant speed, driving the cam body 231 to rotate at a constant speed, and the rocker arm 232 swings to the position shown in (b) of the diagram. Figure 6 As shown in (a), the rocker arm 232 swings from the left limit position of the preset swing angle range to the right limit position, repeating this cycle. By designing the contour of the cam body 231, it can be ensured that the rocker arm 232 swings back and forth at a constant speed within the preset swing angle range. At the same time, since the mirror 22 and the rocker arm 232 are rigidly connected, the constant reciprocating swing of the rocker arm 232 can enable the mirror 22 to complete one constant reciprocating swing.

[0055] Each time the optical board 13 of the transceiver module 1 drives the transmitting module 11 to start measurement, the transmitting module 11 generates a linear laser beam, which is reflected by the tilting mirror 22. The uniform reciprocating swing of the tilting mirror 22 can change the horizontal angle of the beam emitted by the transmitting module 11, and at the same time, it can change the horizontal angle of the beam received by the receiving module 12, thereby scanning target objects at different angles and realizing one-dimensional scanning of the linear laser. The lidar system realizes three-dimensional scanning through one-dimensional scanning of the linear laser. After the tilting mirror 22 completes one uniform swing, the main board 3 can output a complete frame of point cloud information.

[0056] This invention employs a tilting mirror as the core optical element of the scanning module. Its reciprocating oscillation achieves horizontal scanning, avoiding the need for a fully rotating transceiver module or complex optical path folding structures. This reduces the path length of the transmitted and received rays within the module, thereby decreasing the module's vertical height. Furthermore, since the transceiver module is fixed and uses a one-dimensional linear laser array, the vertical field of view is determined by the laser's emission angle and receiving field of view, easily achieving a large vertical field of view without being constrained by the scanning structure. Therefore, the overall system height is reduced. This solution also simplifies electrical and communication design by fixing the transceiver module and driving only the tilting mirror for scanning, allowing direct connection of power and communication lines. The scanning module uses a cam body in conjunction with a swing arm to convert the uniform rotation of the driving component into the uniform reciprocating oscillation of the tilting mirror. This method is simple, reliable, low-cost, and facilitates precise angle control and repeatable positioning. Compared to a drive motor directly driving the tilting mirror, this solution uses a common motor connected to a cam mechanism to achieve oscillation, eliminating the need for motor reciprocating oscillation and reducing overall system complexity and cost.

[0057] Furthermore, this invention also proposes a cam forming method, applied to the three-dimensional lidar system based on one-dimensional linear array scanning described in the above embodiments. The specific structure of the one-dimensional linear array scanning three-dimensional lidar system is as described in the above embodiments. The forming method includes: Define the motion target of the cam body and obtain the preset swing angle range of the rocker arm; A connection angle is reserved at the extreme position of the swing angle; A mathematical model of the cam body profile is established based on the rotation angle of the cam body and the swing angle of the rocker arm. The theoretical profile point set of the cam body is obtained based on the mathematical model of the cam body profile. Output the profile of the cam body.

[0058] This embodiment provides a method for forming a cam in the scanning module of the aforementioned three-dimensional LiDAR system. The method follows a logical flow from motion requirements to geometric contour generation, and the specific steps are as follows: S1: Define the motion target of the cam body and obtain the preset swing angle range of the rocker arm; First, based on the overall performance indicators of the 3D LiDAR system, the motion target of the cam body is defined. Specifically, the cam body drives the rocker arm and the mirror to oscillate back and forth at a uniform speed.

[0059] At the same time, key mechanical design input parameters are obtained, mainly including: The preset swing angle range of the rocker arm: that is, the horizontal field of view that the mirror needs to cover. For example, if the rocker arm is set to swing by an angle α_max on both sides of the center position, then its total swing range is ±α_max. The length L of the rocker arm (the distance from the mirror axis to the center of the roller). The reference mounting position of the cam body, that is, the initial relative position (eccentricity e) between its rotation center and the mirror axis.

[0060] S2: A connection angle is reserved at the extreme swing position.

[0061] To ensure smooth movement and considering mechanical tolerances and assembly errors, a small connection angle is reserved at the theoretical swing angle limit positions (first swing limit position A and second swing limit position B) determined in step S1. The reserved connection angle area corresponds to the theoretical design start and end points of the "smooth transition section". This ensures that the roller has entered the smooth transition zone during actual reversal, thereby avoiding impact at the rigid limit position.

[0062] To ensure the smoothness and feasibility of the motion, specific transition angles are reserved at both ends of the uniform swing angle range, for example... Figure 7 In section (b), φ2 to φ3 and φ4 to φ1 are used for the acceleration start, deceleration stop and motion reversal of the pendulum, to ensure the continuity of the pendulum swing speed and acceleration and to avoid rigid impact.

[0063] S3: Establish a mathematical model of the cam body profile.

[0064] The swing pattern of the rocker arm includes uniform swing and smooth transition. The cam body reserves connection angles at both ends of the uniform swing angle range of the rocker arm: φ2~φ3 and φ4~φ1. During the process of the cam body rotating uniformly around the central axis of the cam body for one revolution, the rocker arm realizes one reciprocating swing within the preset swing angle range. When the rotation angle φ of the cam body is in the range of φ1~φ2 and φ3~φ4, the swing angle α of the rocker arm and the rotation angle φ of the cam body have a linear function relationship. The contour of the cam body corresponds to the uniform swing of the rocker arm as the uniform swing segment, and the contour of the cam body corresponds to the smooth transition of the rocker arm as the smooth transition segment.

[0065] Establish an angle mapping function: Based on the requirement of uniform reciprocating oscillation, establish a linear function relationship between the uniform rotation angle φ of the cam body and the swing angle α of the rocker arm. That is, α = k φ+b (where k and b are constants, representing the change in the swing angle of the rocker arm caused by a unit angle of rotation of the cam body).

[0066] Based on the aforementioned functional relationship α = f(φ), and combined with the known rocker arm length L, eccentricity e, and coordinates of the cam body's rotation center, the coordinate design of the theoretical profile of the cam body is performed using the inversion method. For the roller structure, the actual working profile of the cam body is a normal equidistant curve of the theoretical profile, with an offset distance equal to the roller radius.

[0067] S4: Verify and optimize the pressure angle, and perform contour iteration.

[0068] After obtaining the initial theoretical profile point set of the cam body, mechanical performance verification and optimization are performed to ensure good force transmission performance and avoid self-locking. The pressure angle γ refers to the pressure angle between the cam body and the rocker arm, that is, the acute angle between the common normal direction and the center velocity direction of the roller at the contact point between the cam body and the roller. If the pressure angle is too large, it will lead to a decrease in the effective driving force component, an increase in the required driving torque, and even cause the mechanism to jam. Based on the profile obtained in step S3, the change curve of the pressure angle γ(φ) is calculated throughout the entire motion cycle. The pressure angle is checked to ensure that it is always less than the allowable pressure angle [γ]. If the pressure angle is too large at certain positions (especially near the extreme positions), it is necessary to return to step S3 and adjust the initial design parameters, for example, by appropriately increasing the cam base circle radius. The direction or size of the eccentricity e between the rotation center of the cam body and the rocker arm axis is optimized. The slope of the angle mapping function f(φ) near the extreme region is fine-tuned. Then, the profile of the cam body is recalculated based on the new parameters, and the pressure angle is checked again. This process can be iterated and optimized multiple times until a comprehensive optimal cam body profile is obtained that satisfies the motion law (uniform speed), has a smooth transition section, and has pressure angles within an excellent range throughout the entire cycle.

[0069] S5: Output cam body profile.

[0070] The discrete coordinate point set of the theoretical profile of the cam body, which is finally optimized and determined through steps S3 and S4, is output in a data format that meets the requirements of CNC machining. This data can be directly used to drive high-precision CNC machine tools (such as five-axis machining centers and slow wire EDM machines) or precision injection molds to manufacture a solid cam body that meets the design requirements.

[0071] Optionally, such as Figure 7 As shown in (a), during one revolution of the cam body around its central axis at a constant speed, the rocker arm performs one reciprocating oscillation within a preset oscillation angle range, with both forward and reverse oscillations occurring at a constant speed. Figure 7As shown in (b), motion simulation analysis reveals that when the rotation angle φ of the cam body is within the range of φ1~φ2 and φ3~φ4, the swing angle α of the rocker arm has a linear relationship with the rotation angle φ of the cam body. When the cam body rotates at a constant speed, the cam body rotates from φ1 to φ2 at a constant speed, and the rocker arm swings from α1 to α2 at a constant speed; when the cam body rotates from φ3 to φ4 at a constant speed, the rocker arm swings from α2 to α1 at a constant speed, thus achieving the uniform reciprocating swing of the rocker arm.

[0072] The cam forming method proposed in this embodiment precisely defines the motion law of the rocker arm, which includes a uniform oscillation segment and a smooth transition segment. It then uses the principle of motion reversal for mathematical modeling, ultimately calculating the precise contour of the cam body that meets the specific uniform reciprocating oscillation requirements. Its core lies in achieving a controllable and precise transformation of the motion law into the geometry of the mechanism, ensuring that the rocker arm oscillates strictly at a uniform speed within a preset oscillation angle range.

[0073] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of protection of the present invention. Any equivalent structural transformations made based on the inventive concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A three-dimensional lidar system based on one-dimensional linear array scanning, characterized in that, include: The transceiver module is used to transmit and receive linear laser beams; as well as The scanning module includes a tilting mirror, a driving component, and a cam mechanism. The tilting mirror reflects the linear laser beam. The cam mechanism is a cam-rocker mechanism and includes a cam body and a rocker arm. The driving component is connected to the cam body and drives the cam body to rotate at a constant speed. The tilting mirror is connected to the rocker arm, and the rocker arm is connected to the cam body. The cam body rotates at a constant speed and drives the tilting mirror to oscillate back and forth at a constant speed within a preset angle through the rocker arm, thereby changing the angle at which the transceiver module transmits and receives the linear laser beam in the horizontal direction.

2. The three-dimensional lidar system based on one-dimensional linear array scanning as described in claim 1, characterized in that, The cam body is provided with a guide portion, and the end of the rocker arm away from the rocker mirror moves along the guide portion.

3. The three-dimensional lidar system based on one-dimensional linear array scanning as described in claim 2, characterized in that, The guide portion is configured as a groove, and one end of the rocker arm is provided with a roller. The roller is movably disposed in the groove and contacts the inner wall of the groove.

4. The three-dimensional lidar system based on one-dimensional linear array scanning as described in claim 2, characterized in that, The guide portion is arranged around the rotation center of the cam body. The rocker arm has a first swing limit position and a second swing limit position, and the two are arranged symmetrically. At the first swing limit position or the second swing limit position, the connection point between the rocker arm and the guide portion is M. The line connecting point M and the rotation center of the cam body is the swing axis of the cam body. When the rocker arm moves from the first swing limit position to the second swing limit position or from the second swing limit position to the first swing limit position, the swing angle of the rocker arm and the rotation angle of the swing axis are a linear function relationship.

5. The three-dimensional lidar system based on one-dimensional linear array scanning as described in claim 4, characterized in that, The guide section further includes a smooth transition section, which corresponds to the first swing limit position and the second swing limit position.

6. The three-dimensional lidar system based on one-dimensional linear array scanning as described in claim 1, characterized in that, The three-dimensional lidar system also includes a support base with a rotating shaft. The swing mirror is rotatably connected to the rotating shaft. The drive component is fixedly mounted on the support base, and the output shaft of the drive component is connected to the cam body.

7. The three-dimensional lidar system based on one-dimensional linear array scanning as described in claim 1, characterized in that, The three-dimensional lidar system also includes a motherboard electrically connected to the driving component. The transceiver module includes a transmitting module, a receiving module, and an optical board. The transmitting module and the receiving module are respectively disposed on the optical board, which is electrically connected to the motherboard. The transmitting module is used to emit a linear laser beam. The linear laser beam is reflected by the tilting mirror and directed toward the target object. The target object reflects the linear laser beam and forms an echo beam. The receiving module is used to receive the echo beam reflected by the tilting mirror.

8. A method for forming a cam, characterized in that, Applied to the three-dimensional lidar system based on one-dimensional linear array scanning as described in any one of claims 1-7, wherein the forming method includes: Define the motion target of the cam body and obtain the preset swing angle range of the rocker arm; A connection angle is reserved at the extreme position of the swing angle; A mathematical model of the cam body profile is established based on the rotation angle of the cam body and the swing angle of the rocker arm. The theoretical profile point set of the cam body is obtained based on the mathematical model of the cam body profile. Output the profile of the cam body.

9. The cam forming method as described in claim 8, characterized in that, The swing pattern of the rocker arm includes uniform swing and smooth transition. The cam body reserves connection angles at both ends of the uniform swing angle range of the rocker arm: φ2~φ3 and φ4~φ1. During the process of the cam body rotating uniformly around the central axis of the cam body for one revolution, the rocker arm realizes one reciprocating swing within the preset swing angle range. When the rotation angle φ of the cam body is in the range of φ1~φ2 and φ3~φ4, the swing angle α of the rocker arm and the rotation angle φ of the cam body have a linear function relationship. The contour of the cam body corresponds to the uniform swing of the rocker arm as the uniform swing segment, and the contour of the cam body corresponds to the smooth transition of the rocker arm as the smooth transition segment.

10. The cam forming method as described in claim 8, characterized in that, Before outputting the profile of the cam body, the pressure angle between the rocker arm and the cam body is checked and optimized, and the profile of the cam body is optimized through multiple iterations.

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