Optical scanning system and mobile robot

Abstract

This application discloses an optical scanning system and a mobile robot, relating to the field of environmental perception technology. The optical scanning system includes: a first optical element, including a first reflective surface, rotating around a first rotation axis at a first rotational speed; a second optical element, including a second reflective surface, rotating around a second rotation axis at a second rotational speed different from the first rotational speed; and a transmitting and receiving module for emitting incident light and receiving reflected light from the incident light. The incident light is emitted onto the object to be scanned via the first and second reflective surfaces to generate reflected light, and the reflected light returns to the transmitting and receiving module via the second and first reflective surfaces for reception. This application proposes a novel scanning method that, by setting two optical elements with different rotational speeds, both of which can reflect light, achieves the point cloud effect of traditional multiple lasers using only a few lasers, enabling three-dimensional scanning with lidar.

Description

Technical Field

[0001] This application relates to the field of environmental perception technology, and more specifically to an optical scanning system and a mobile robot. Background Technology

[0002] With the development of fields such as autonomous driving, robot navigation, and geographic mapping, the demand for environmental perception technologies is increasing. For example, LiDAR, as an important remote sensing technology, plays a key role in these fields due to its high precision, long-range detection capabilities, and ability to operate under various lighting conditions.

[0003] However, to improve the resolution of point clouds, traditional multi-line lidar often employs a large number of stacked lasers, requiring multiple laser emitter and receiver arrays to achieve multiple scan lines. This not only increases system complexity but also results in a larger device size. Furthermore, the multiple lasers and complex mechanical structure in traditional multi-line lidar lead to higher maintenance costs, impacting overall cost. Utility Model Content

[0004] The purpose of this application is to provide an optical scanning system and a mobile robot, proposing a new scanning method that can achieve the point cloud effect of traditional multiple lasers using a few lasers, thus realizing three-dimensional scanning of lidar.

[0005] To achieve the above objectives, a first aspect of this application provides an optical scanning system, comprising: a first optical element including a first reflective surface, rotating about a first rotation axis at a first rotational speed; a second optical element including a second reflective surface, rotating about a second rotation axis at a second rotational speed different from the first rotational speed; and a transmit-receive module for emitting incident light and receiving reflected light from the incident light, wherein the incident light is emitted onto an object to be scanned via the first and second reflective surfaces to generate the reflected light, and the reflected light returns to the transmit-receive module via the second and first reflective surfaces for reception.

[0006] In the embodiments of this application, the first rotation axis and the second rotation axis are collinear or not collinear; and / or the rotation directions of the first optical element and the second optical element are the same or opposite.

[0007] In this embodiment of the application, the angle between the first rotation axis and the second rotation axis is 0-30 degrees.

[0008] In this embodiment of the application, the first speed is 3000-18000 rpm, the second speed is 3000-18000 rpm; and / or the speed difference between the first speed and the second speed is greater than or equal to 60 rpm.

[0009] In this embodiment, the transmitting and receiving module is a single laser device or a laser array composed of multiple laser devices; the first optical element is a mirror, prism, or MEMS system, and the first reflecting surface is a plane or a curved surface; and / or the second optical element is a mirror or prism, and the second reflecting surface is a plane or a curved surface.

[0010] In this embodiment of the application, when both the first reflective surface and the second reflective surface are planar, the angle between the first reflective surface and the first rotation axis is greater than 0 degrees and less than or equal to 60 degrees; and / or the angle between the second reflective surface and the second rotation axis is 20-50 degrees.

[0011] In this embodiment, the first optical element is a plane mirror, the second optical element is a right-angle prism, and the second optical element further includes a first refractive surface and a second refractive surface. The second reflective surface is the inclined surface of the right-angle prism, and the first and second refractive surfaces are the right-angle surfaces of the right-angle prism. The incident light is emitted onto the object to be scanned via the first reflective surface, the first refractive surface, the second reflective surface, and the second refractive surface to generate the reflected light. The reflected light returns to the transmitting and receiving module for reception via the second refractive surface, the second reflective surface, the first refractive surface, and the first reflective surface.

[0012] In the embodiments of this application, the longest side dimension of the first optical element is 0.3-30cm; and / or the longest side dimension of the second optical element is 1cm-60cm.

[0013] In this embodiment of the application, the optical scanning system further includes: a control module, used to adjust the rotation direction and the first rotation speed of the first optical element; and / or adjust the rotation direction and the second rotation speed of the second optical element.

[0014] In this embodiment of the application, the optical scanning system further includes: a point cloud analysis module, used to output a point cloud scanning pattern of the object to be scanned based on a first angle between the incident light and the first rotation axis and a second angle between the first rotation axis and the second rotation axis.

[0015] This application also provides a mobile robot, including the optical scanning system described above.

[0016] Through the above technical solution, this application proposes a new scanning method. By setting two optical elements with different rotation speeds, both optical elements can reflect light, thereby achieving the point cloud effect of traditional multiple lasers with a few lasers, and realizing three-dimensional scanning of lidar. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings:

[0018] Figure 1 A schematic diagram of the structure of an optical scanning system according to an embodiment of this application is shown.

[0019] Figure 2 This illustration schematically shows a diagram illustrating the calculation of the reflection angle of an optical scanning system according to an embodiment of this application;

[0020] Figures 3-10 This illustration schematically shows a process by which an optical scanning system according to an embodiment of this application obtains a point cloud scanning pattern;

[0021] Figure 11 This illustration schematically shows a scanning diagram of a lidar according to an embodiment of this application;

[0022] Figure 12 The diagram illustrates the point cloud distribution analysis process according to an embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0024] It should be noted that if the embodiments of this application 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 certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0025] Furthermore, if the embodiments of this application 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. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of 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. If 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 in this application.

[0026] First, embodiments of this application provide an optical scanning system, such as Figure 1 As shown, the optical scanning system may include a first optical element 10, a second optical element 20, and a transmit / receive module 30.

[0027] The first optical element 10 may include a first reflective surface 11, and the first optical element 10 may rotate about a first rotation axis 12 at a first rotational speed. Figure 2 As shown, the first optical element 10 can rotate around the first rotation axis z with an angular velocity ω1. In one embodiment, the first rotational speed can be 3000-18000 rpm (revolutions per minute), such as 3000 rpm, 4000 rpm, 5000 rpm, 10000 rpm, 11000 rpm, 12000 rpm, 15000 rpm, 18000 rpm, etc. The longest side dimension of the first reflecting surface 11 is 0.3-30 cm, such as 0.3 cm, 0.5 cm, 1 cm, 1.1 cm, 1.2 cm, 1.3 cm, 1.5 cm, 2 cm, 3 cm, 5 cm, 10 cm, 15 cm, 20 cm, 30 cm, etc. The first reflecting surface 11 can be, but is not limited to, a mirror, a prism, or a MEMS system, such as a plane mirror. The first reflecting surface 11 can be planar or curved. When the first reflecting surface 11 is a plane, its normal vector is n0, and the incident ray makes an angle θ1 with the normal of the first reflecting surface 11, thereby reflecting the incident ray. In one embodiment, the angle between the first reflecting surface 11 and the first rotation axis 12 is greater than or equal to 60 degrees and less than 90 degrees, that is, 60°≤θ1<90°, for example 60°, 65°, 70°, 75°, 80°, 85°, 89°, etc.

[0028] The second optical element 20 may include a second reflective surface 21, and the second optical element 20 can rotate around a second rotation axis 22 at a second rotational speed different from the first rotational speed. Because the two optical elements rotate at different speeds, three-dimensional scanning of the lidar is achieved. Figure 2As shown, the second optical element 20 rotates around the second rotation axis 22 at an angular velocity ω2, while the first optical element 10 rotates in the same or opposite directions as the second optical element 20. The first rotation axis 12 and the second rotation axis 22 may be collinear or non-collinear. For example, the angle between the first rotation axis 12 and the second rotation axis 22 is 0-30 degrees. In one embodiment, the second rotation speed can be 3000-18000 rpm, such as 3000 rpm, 4000 rpm, 5000 rpm, 10000 rpm, 11000 rpm, 12000 rpm, 15000 rpm, 18000 rpm, etc. The two optical elements need to rotate with a certain speed difference to achieve three-dimensional scanning. For example, the speed difference between the first and second rotation speeds is greater than or equal to 60 rpm, such as 60 rpm, 70 rpm, 80 rpm, 90 rpm, 100 rpm, 150 rpm, 200 rpm, 500 rpm, 1000 rpm, etc. The longest side of the second reflecting surface of the second optical element 20 is 1-60cm, for example, 1cm, 1.5cm, 2cm, 2.5cm, 3cm, 3.5cm, 4cm, 4.5cm, 5cm, 10cm, 15cm, 20cm, 25cm, 30cm, 40cm, 50cm, 60cm, etc., and may include, but is not limited to, mirrors, prisms, or MEMS systems, such as right-angle prisms. The second reflecting surface 21 can be planar or curved. When the second reflecting surface 21 is planar, its normal vector is n2. In one embodiment, the angle between the second reflecting surface 21 and the second rotation axis 22 is 20-50 degrees, for example, 20°, 25°, 30°, 35°, 40°, 45°, 50°, etc.

[0029] The transmitting and receiving module 30 includes a laser emitter and a laser receiver, which can be a single laser device or a laser array composed of multiple laser devices. It is used to emit incident light and receive the reflected light from the incident light. The incident light is emitted onto the object to be scanned via a first reflecting surface 11 and a second reflecting surface 21 to generate reflected light. The reflected light returns to the transmitting and receiving module 30 via the second reflecting surface 21 and the first reflecting surface 11 for reception.

[0030] The applicant has found that traditional multi-line lidar, once designed, typically has a fixed scanning mode, making dynamic adjustment difficult based on specific circumstances. To address this, in this application's embodiment, the optical scanning system may further include a control module. This control module is used to adjust the rotation direction and first rotational speed of the first optical element 10; and / or adjust the rotation direction and second rotational speed of the second optical element 20. Thus, the optical scanning system of this application can have a flexible scanning mode; that is, by controlling the rotational speed and direction of the two optical elements, the scanning density and coverage can be flexibly adjusted to adapt to different application scenarios.

[0031] In the embodiments of this application, such as Figure 2 As shown, the first optical element 10 is a plane mirror, and the second optical element 20 is a right-angled triangular prism. The second optical element 20 may also include a first refractive surface 23 and a second refractive surface 24. The second reflecting surface 21 is the inclined surface of the right-angled triangular prism, and the first refractive surface 23 and the second refractive surface 24 are the right-angled surfaces of the right-angled triangular prism. Incident light rays are emitted onto the object to be scanned via the first reflecting surface 11, the first refractive surface 23, the second reflecting surface 21, and the second refractive surface 24, generating reflected light rays. The reflected light rays return to the transmitting and receiving module 30 for reception via the second refractive surface 24, the second reflecting surface 21, the first refractive surface 23, and the first reflecting surface 11.

[0032] In this embodiment of the application, the optical scanning system may further include: a point cloud analysis module, used to output a point cloud scanning pattern of the object to be scanned based on a first angle between the incident light and the first rotation axis 12 and a second angle between the first rotation axis 12 and the second rotation axis 22.

[0033] Specifically, a world coordinate system can be established at point o in the first reflecting surface 11 of the first optical element 10. The first optical element 10 rotates with an angular velocity ω1, and the rotation angle is... The second optical element 20 is a right-angle prism that rotates at an angular velocity ω2. The rotation angle is... Since light travels through space, according to Snell's theorem, we can deduce that:

[0034] The spatial normal vector of the incident ray is:

[0035]

[0036] The unit vector of the reflected ray OA after reflection by the first reflecting surface 11 of the first optical element 10 is:

[0037]

[0038] After refraction by the first surface (first refractive surface 23) of the second optical element 20, the unit vector of the refracted ray AB is:

[0039]

[0040] Light ray AB is reflected by the second surface of the prism (first reflecting surface 11), and the unit vector of the reflected light ray BC is:

[0041]

[0042] The ray BC is refracted by the third surface (second refractive surface 24) of the prism, and the unit vector of the refracted ray CD is:

[0043]

[0044] Where t is time; γ0 is the angle between the reflecting surface of the first optical element and the horizontal plane; γ1 is the angle between the reflecting surface (i.e., the second surface) of the second optical element and the horizontal plane; n0 is the vector of the reflecting surface of the first optical element; θ1 is the angle between the incident ray and the normal vector n0 of the reflecting surface of the first optical element; n is the refractive index of the first and second optical elements; n2 is the direction of the reflecting surface (i.e., the second surface) of the second optical element; n3 is the direction of the exiting surface (i.e., the third surface) of the second optical element; points A, B, and C are the intersection points of the ray with the first, second, and third surfaces of the second optical element, respectively.

[0045] For example, the angle between the emitted light from the emitting module and the normal to the reflecting surface of the first optical element 10 is 1.2°, and the tilt angle between the first reflecting surface 11 of the first optical element 10 and the horizontal plane is 8.5°; the second optical element 20 is a right-angled prism, with its inclined surface being the second reflecting surface 21, and the tilt angle being 50°. Both optical elements are made of H-ZlaF90, which has a refractive index of approximately 1.9736 at a wavelength of 905 nm. In some embodiments, it is assumed that the rotational speed of the emitting module is v1, and the rotational speed of the scanning optical element is v2, both rotating in the same direction, counterclockwise. For example, in this LiDAR system, the laser emitting module and the scanning element rotate in the same direction at high speed; the rotational speed v1 of the laser emitting module is 11148 rpm, and the rotational speed v2 of the optical scanning element is 11298 rpm. The integration time of the point cloud in the scanned pattern is 1 second, and the simulated distance is 100 meters. An exemplary point cloud scanning pattern can then be obtained using a LiDAR system with a single-line laser diode having a light source emission frequency of 20 kHz. The process can be described as follows: Figures 3-8 As shown:

[0046] Specifically, Figure 3This is a 3D point cloud image with an integration time of 0.2s. The XYZ coordinate system is a spatial coordinate system, and the unit is meters. It shows the radar's scanning trajectory in space as the integration time progresses. The colors in the grayscale bars represent the integration time, in seconds. The horizontal scanning range is 360°, and the vertical scanning range is 12.40° to 53.24°. Figure 4 for Figure 3 Top view.

[0047] Figure 5 The distribution of the lidar point cloud at different angles is shown. The horizontal coordinate (H_angle) represents the horizontal field of view, with the lidar horizontal scanning range of 0 to 360° and the average horizontal angular resolution of the point cloud of 0.34°. The vertical coordinate (V_angle) represents the vertical field of view, with the vertical scanning range of 12.40° to 53.24° and the average vertical angular resolution of 1.11°. Figure 6 This is a 3D point cloud image with an integration time of 1 second. The coordinate system XYZ is a spatial coordinate system, and the unit is meters. It shows the radar's scanning trajectory in space over time, with an integration time of 1 second. Figure 7 The graph shows the change in point cloud coverage rate of lidar as a function of integration time. The vertical axis (cover rate) represents the coverage rate of the point cloud, and the horizontal axis (times) represents the time integration, with the unit being seconds. It indicates that the point cloud coverage rate reaches 92.31% when the integration time is 1 second.

[0048] Figure 8 The point cloud distribution map with an integration time of 1 second is shown. The horizontal axis H_angle represents the horizontal field of view, with an average angular resolution of 0.28°. The vertical axis (V_angle) represents the vertical field of view, with an average vertical angular resolution of 0.27°. Figure 9 for Figure 8 A magnified view of a portion of the image.

[0049] Figure 11 This is a schematic diagram of a lidar scan, from which the following can be calculated. Figure 10 The coverage statistics chart. For example, the coverage of a lidar field of view can be defined as the ratio of the filled grid to the total grid. The chromaticity bar represents the number of laser points falling within the smallest grid. For example, ... Figure 11 As shown, V_angle represents the vertical angle of a point cloud point, and H_angle represents the horizontal angle of a point cloud point. When analyzing point cloud distribution, it is necessary to set an initial grid size and evaluate the point cloud based on whether there are discrete points distributed within different grid cells. For example... Figure 12 As shown, after gridding, each grid contains discrete points, resulting in good point cloud coverage. When a LiDAR laser point falls into a small grid cell, it is considered to have filled that grid cell. Figure 12 As shown by the small black squares in the diagram, the point cloud coverage C is defined as:

[0050]

[0051] As can be seen from the above embodiments, the reflection-based scanning method proposed in this patent can achieve the point cloud effect of multiple lasers with fewer lasers. Beneficial effects include:

[0052] 1) Simplified Structure and Reduced Size: Traditional multi-line lidar typically requires multiple laser emitters and receiver arrays to achieve multiple scan lines. This not only increases the complexity of the system but also results in a larger device size. The scanning method proposed in this patent reduces the number of laser sources required, thereby greatly simplifying the structure and making the entire system more compact.

[0053] 2) Cost Reduction: The multiple lasers and complex mechanical structure in traditional multi-line lidar systems lead to high maintenance costs. Manufacturing costs are reduced by using fewer laser sources and other optical components. Furthermore, the simplified design reduces assembly and calibration work, further lowering production costs.

[0054] 3) Flexible scanning modes: By controlling the rotation speed and angle of the two optical elements, the scanning density and coverage can be flexibly adjusted to adapt to different application scenarios. Traditional multi-line lidar, once designed, typically has a fixed scanning mode, making dynamic adjustment difficult based on specific circumstances.

[0055] Furthermore, the LiDAR based on the scanning mode proposed in this patent has a wide range of applications. For example, it can be used for environmental perception in autonomous vehicles, providing high-precision 3D environmental models to help vehicles identify roads, pedestrians, obstacles, etc. It can also be used for path planning in autonomous vehicles, using real-time generated point cloud data to assist vehicles in dynamic path planning and avoid collisions. Additionally, it can be used for localization and navigation in autonomous vehicles, combining SLAM technology to achieve precise vehicle positioning in complex environments. Furthermore, it can be used for indoor navigation of robots in environments such as warehouses, factories, and hospitals, helping robots avoid obstacles and navigate autonomously. It can also be applied to self-moving devices such as drones, lawnmowers, and robotic vacuum cleaners.

[0056] On the other hand, this application also provides a mobile robot that may include the optical scanning system described above.

[0057] Among them, mobile robots can be cars, robots, factory self-propelled vehicles, sweepers, lawnmowers, drones, etc., and dense point cloud data can build more detailed and accurate environmental maps.

[0058] The beneficial effects of the mobile robot provided in this application can be referred to the above description of the optical scanning system, and will not be repeated here.

[0059] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0060] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. An optical scanning system, characterized in that, The optical scanning system includes: A first optical element, including a first reflective surface, rotates about a first rotation axis at a first rotational speed; A second optical element, including a second reflective surface, rotates about a second rotation axis at a second rotational speed different from the first rotational speed; and A transmit-receive module is used to emit incident light and receive the reflected light of the incident light, wherein the incident light is emitted onto the object to be scanned via a first reflective surface and a second reflective surface to generate the reflected light, and the reflected light returns to the transmit-receive module via the second reflective surface and the first reflective surface for reception.

2. The optical scanning system according to claim 1, characterized in that, The first rotation axis may be collinear with or not collinear with the second rotation axis.

3. The optical scanning system according to claim 2, characterized in that, The angle between the first rotation axis and the second rotation axis is 0-30 degrees.

4. The optical scanning system according to claim 1, characterized in that, The first optical element and the second optical element rotate in the same or opposite directions.

5. The optical scanning system according to claim 1, characterized in that, The first speed is 3000-18000 rpm, and the second speed is 3000-18000 rpm.

6. The optical scanning system according to claim 1, characterized in that, The speed difference between the first speed and the second speed is greater than or equal to 60 rpm.

7. The optical scanning system according to claim 1, characterized in that, The transmitting and receiving module is a single laser device or a laser array composed of multiple laser devices.

8. The optical scanning system according to claim 1, characterized in that, The first optical element is a mirror, prism, or MEMS system, and the first reflecting surface is a plane or a curved surface; The second optical element is a mirror or a prism, and the second reflecting surface is a plane or a curved surface.

9. The optical scanning system according to claim 8, characterized in that, When the first reflecting surface is a plane, the angle between the first reflecting surface and the first rotation axis is greater than or equal to 60 degrees and less than 90 degrees.

10. The optical scanning system according to claim 8, characterized in that, When the second reflecting surface is a plane, the angle between the second reflecting surface and the second rotation axis is 20-50 degrees.

11. The optical scanning system according to claim 8, characterized in that, The first optical element is a plane mirror, and the second optical element is a right-angle prism. The second optical element also includes a first refractive surface and a second refractive surface. Wherein, the second reflecting surface is the inclined surface of the right-angled prism, and the first and second refracting surfaces are the right-angled surfaces of the right-angled prism. The incident light is emitted onto the object to be scanned via a first reflecting surface, a first refractive surface, a second reflecting surface, and a second refractive surface to generate the reflected light. The reflected light then returns to the transmitting and receiving module via a second refractive surface, a second reflecting surface, a first refractive surface, and a first reflecting surface for reception.

12. The optical scanning system according to claim 1, characterized in that, The longest side of the first optical element is 0.3-30cm.

13. The optical scanning system according to claim 1, characterized in that, The longest side of the second optical element is 1cm-60cm.

14. The optical scanning system according to any one of claims 1-13, characterized in that, The optical scanning system further includes: a control module for adjusting the rotation direction of the first optical element and the first rotation speed; or Adjust the rotation direction of the second optical element and the second rotation speed.

15. The optical scanning system according to any one of claims 1-13, characterized in that, The optical scanning system further includes a point cloud analysis module, used to output a point cloud scanning pattern of the object to be scanned based on a first angle between the incident light and the first rotation axis and a second angle between the first rotation axis and the second rotation axis.

16. A mobile robot, characterized in that, Includes the optical scanning system as described in any one of claims 1-15.

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