TOF module for sweeping robot and sweeping robot

Abstract

A time-of-flight (TOF) module for a sweeping robot and the sweeping robot. The TOF module for the sweeping robot comprises a projection module and a receiving module. The projection module is adapted to be mounted on the sweeping robot body and is used to project an output light field, wherein the ratio of the horizontal angle to the vertical angle of the output light field is greater than 10. The receiving module is adapted to be mounted on the sweeping robot body and is used to receive the reflected light field, thereby performing distance measurement using the TOF principle.

Description

Technical Field

[0001] The present invention relates to the field of machine vision technology, and more particularly to a TOF module for a sweeping robot and the sweeping robot. Background Art

[0002] The Time of Flight (TOF) method measures the three-dimensional structure or three-dimensional contour of an environmental target by measuring the time interval t between the emission and reception of a pulse signal emitted by a projection module (often called pulse ranging method) or the phase generated by a laser's round trip to an environmental target (phase difference ranging method). As a highly accurate ranging instrument, the TOF module is widely used in many fields such as somatosensory control, behavior analysis, monitoring, autonomous driving, artificial intelligence, machine vision, and automatic 3D modeling. Different application fields or application scenarios have different performance requirements for TOF modules, which requires the design of different TOF modules based on specific application fields or application scenarios.

[0003] With the rapid development of science and technology, sweeping robots have gradually entered the public's field of vision and are playing an increasingly important role. However, in the implementation of the projection receiving module of the sweeping robot, the field of view of the current more mature TOF module is usually small, while the sweeping robot requires a larger field of view in the horizontal direction (i.e., the H direction) in order to measure obstacle information over a larger range. At the same time, the sweeping robot requires a smaller field of view in the vertical direction (i.e., the V direction). This is not only because the sweeping robot does not require a large field of view in the V direction, but also to avoid the TOF module's measurement accuracy being affected by ground reflections, which may even cause the TOF module to malfunction.

[0004] Furthermore, the TOF module of most current robot vacuums is located above the robot, with its vertical (V-direction) field of view (FOV) window above the horizontal line. This makes it difficult for the robot to identify obstacles such as feces and the underside of stair lights, affecting its cleaning performance and safety. If the TOF module is located below the horizontal line, the robot's structure will block the light projected by the projection and receiving module, making it impossible to accurately measure distances and even causing the robot to malfunction. Summary of the Invention

[0005] An object of the present invention is to provide a TOF module for a sweeping robot and a sweeping robot, which can provide a larger horizontal field of view angle and a smaller vertical field of view angle, helping to meet the actual measurement needs of the sweeping robot.

[0006] Another object of the present invention is to provide a TOF module for a sweeping robot and a sweeping robot. In one embodiment of the present invention, the TOF module is suitable for being installed on the side of the sweeping robot body, which helps the sweeping robot to achieve obstacle avoidance function in places such as stairs and feces.

[0007] Another object of the present invention is to provide a TOF module for a sweeping robot and a sweeping robot. In one embodiment of the present invention, the light intensity distribution of the output light field of the projection module of the TOF module in the horizontal direction satisfies And N = cos m (θ max ), m>1, so that the receiving module of the TOF module receives a receiving light field with a relatively uniform light intensity distribution, which helps to improve the measurement accuracy of the TOF module.

[0008] Another object of the present invention is to provide a TOF module and a sweeping robot for a sweeping robot. In one embodiment of the present invention, the ratio between the maximum and minimum values ​​of the light intensity distribution in the horizontal direction of the output light field of the projection module of the TOF module is not less than 3, which helps to take into account the ranging range required by the sweeping robot and the uniformity of the received light field.

[0009] Another object of the present invention is to provide a TOF module and a sweeping robot for a sweeping robot. In one embodiment of the present invention, the receiving module can utilize the light energy of a partially blurred area in the output light field of the projection module, which helps to improve the light energy utilization rate of the TOF module.

[0010] Another object of the present invention is to provide a TOF module and a sweeping robot for a sweeping robot. In one embodiment of the present invention, the angle of the blurred area of ​​the output light field of the projection module in the vertical direction is not greater than 2°, which helps to prevent the measurement results of the TOF module from being affected by ground reflections.

[0011] Another object of the present invention is to provide a TOF module and a sweeping robot for a sweeping robot. In one embodiment of the present invention, the vertical field of view angle of the output light field of the projection module is not greater than 5°, which helps to concentrate the total light intensity of the output light field so as to improve the ranging range of the TOF module.

[0012] Another object of the present invention is to provide a TOF module and a sweeping robot for a sweeping robot. In one embodiment of the present invention, the main light inclination angle of the photosensitive module in the receiving module and the main light inclination angle of the lens module may not match, which helps to increase the relative illumination of the lens module by adjusting the main light inclination angle of the photosensitive module and / or the lens module.

[0013] Another object of the present invention is to provide a TOF module and a sweeping robot for a sweeping robot. In one embodiment of the present invention, the main light inclination angle CRA_S of the photosensitive module in the receiving module and the main light inclination angle CRA_L of the lens module meet the condition: (CRA_S-CRA_L)*RI≥10, which helps to increase the ranging range of the TOF module.

[0014] Another object of the present invention is to provide a TOF module for a sweeping robot and a sweeping robot. In one embodiment of the present invention, the receiving module of the TOF module can compensate the resolution in the vertical resolution direction to the resolution in the horizontal resolution direction, that is, the receiving module can sacrifice the image quality in the vertical direction to improve the image quality in the horizontal direction.

[0015] Another object of the present invention is to provide a TOF module and a sweeping robot for a sweeping robot. In one embodiment of the present invention, the resolution of the receiving module of the TOF module in the vertical resolution direction and the horizontal resolution direction satisfies the relationship: 100*MTF@unin) / (MTF@in*RI)≤3, which helps to effectively improve the relative illumination of the lens module so as to further increase the ranging range of the TOF module.

[0016] Another object of the present invention is to provide a TOF module and a sweeping robot for a sweeping robot. In one embodiment of the present invention, the receiving module can reduce the number of lenses required in the lens module while ensuring that the receiving module has a high resolution, which helps to reduce the structural size of the entire receiving module.

[0017] In order to achieve at least one of the above-mentioned objectives or other objectives and advantages, the present invention provides a TOF module for a sweeping robot, comprising:

[0018] a projection module, wherein the projection module is suitable for being provided on the main body of the sweeping robot, and is used to project an output light field, wherein the ratio of the angle of the output light field in the horizontal direction to the angle in the vertical direction is greater than 10; and

[0019] A receiving module, wherein the receiving module is suitable for being correspondingly arranged on the cleaning robot body, and is used for receiving the reflected receiving light field.

[0020] In one embodiment of the present invention, the projection module is suitable for being installed on the side of the cleaning robot body, and the receiving module is suitable for being correspondingly installed on the side of the cleaning robot.

[0021] In one embodiment of the present invention, the light intensity distribution of the output light field of the projection module in the horizontal direction satisfies Where N = cos m (θ max ), m>1, where θ is the diffraction angle and I is the relative light intensity.

[0022] In one embodiment of the present invention, a ratio between a maximum value and a minimum value of the light intensity distribution of the output light field in the horizontal direction is not less than 3.

[0023] In one embodiment of the present invention, a starting position angle of a blurred area of ​​the output light field in the horizontal direction is smaller than a maximum horizontal field angle of the projection module.

[0024] In one embodiment of the present invention, the angular range of the blurred area of ​​the output light field in the vertical direction is no more than 2°.

[0025] In one embodiment of the present invention, the light intensity distribution of the output light field of the projection module in the horizontal direction satisfies Where m = 1.73.

[0026] In one embodiment of the present invention, the projection module includes a light source module and a diffractive optical element, wherein the diffractive optical element is arranged in the emission path of the light source module and is used to shape the input light field emitted by the light source module to form the output light field.

[0027] In one embodiment of the present invention, the diffractive optical element of the projection module is further used to collimate the input light field emitted by the light source module in a vertical direction.

[0028] In one embodiment of the present invention, the receiving module includes a photosensitive chip and a lens assembly, wherein the lens assembly is correspondingly arranged in the photosensitive path of the photosensitive chip for shaping the received light field, wherein the photosensitive chip and the lens assembly satisfy the condition: (CRA_S-CRA_L)*RI≥10, wherein CRA_S is the main light inclination angle of the photosensitive chip, CRA_L is the main light inclination angle of the lens assembly, and RI is the relative illumination of the lens assembly.

[0029] In one embodiment of the present invention, the relationship between the receiving module and the receiving module satisfies the following: (100*MTF@unin) / (MTF@in*RI)≤3, where MTF@in is the field resolution of the receiving module at 1 Nyquist frequency in the horizontal resolution direction, MTF@unin is the field resolution of the receiving module at 1 Nyquist frequency in the vertical resolution direction, and RI is the relative illumination of the lens assembly.

[0030] In one embodiment of the present invention, the spatial frequency f(MTF>0.5) corresponding to the field resolution MTF>0.5 of the receiving module in the horizontal resolution direction and the number of lenses n of the lens assembly satisfy the relationship: f(MTF>0.5) / (l*n)≥1.0, where l is the total length of the lens assembly.

[0031] According to another aspect of the present invention, the present invention further provides a sweeping robot, comprising:

[0032] A sweeping robot body; and

[0033] Any of the above-mentioned TOF modules, wherein the TOF module is installed on the side of the cleaning robot body.

[0034] Further objects and advantages of the present invention will be fully apparent from an understanding of the following description and accompanying drawings.

[0035] These and other objects, features and advantages of the present invention will be more fully understood from the following detailed description, accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 2 is a schematic structural diagram of a sweeping robot equipped with a TOF module according to an embodiment of the present invention.

[0037] Figure 2 is a system schematic diagram of the TOF module according to the above embodiment of the present invention.

[0038] Figure 3 A schematic diagram of the light intensity distribution in the horizontal direction of the output light field projected by the projection module of the TOF module according to the above embodiment of the present invention is shown.

[0039] Figure 4 A schematic diagram of the light intensity distribution in the vertical direction of the output light field projected by the projection module according to the above embodiment of the present invention is shown.

[0040] Figure 5 A schematic diagram showing the distribution of the output light field projected by the projection module according to the above embodiment of the present invention is shown.

[0041] Figure 6 A schematic diagram of a CRA curve of a lens assembly of a receiving module of the TOF module according to the above embodiment of the present invention is shown.

[0042] Figure 7 A schematic diagram of the RI curve of the lens assembly of the receiving module according to the above embodiment of the present invention is shown.

[0043] Figure 8A schematic diagram of the field of view resolution of the receiving module at 1 Nyquist frequency according to the above embodiment of the present invention is shown. DETAILED DESCRIPTION

[0044] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are for illustrative purposes only, and those skilled in the art will readily appreciate other obvious variations. The basic principles of the present invention defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0045] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0046] In the present invention, the term "a" or "an" in the claims and the specification should be understood as "one or more." That is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple. Unless the disclosure of the present invention clearly indicates that the number of the element is only one, the term "a" or "an" should not be understood as a unique or singular element, and the term "a" or "an" should not be understood as a limitation on the quantity.

[0047] In the description of the present invention, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through a medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0049] As the application scenarios of sweeping robots become more and more complex, people’s expectations for sweeping robots are also getting higher and higher. For example, for duplex or attic rooms, people expect sweeping robots to be able to automatically identify obstacles such as stairs and automatically avoid obstacles. However, the projection receiving module of most sweeping robots is currently located above the sweeping robot, and its vertical field of view window is above the horizontal line, so that the field of view window is located above the sweeping robot, which makes it impossible for the sweeping robot to identify obstacles such as feces and the bottom of stair lights, thereby affecting the cleaning effect and safety performance of the sweeping robot. If a design below the horizontal line is adopted, the structure of the sweeping robot itself will block the light projected by the projection receiving module, making it impossible to accurately measure the distance, and even causing the sweeping robot to fail to work properly.

[0050] In addition, in the implementation scheme of the projection receiving module of the sweeping robot, the field of view of the current more mature TOF module is usually small, while the sweeping robot requires a larger field of view in the horizontal direction (i.e., the H direction) to measure obstacle information over a larger range. At the same time, the sweeping robot needs a smaller field of view in the vertical direction to avoid the TOF module's measurement accuracy being affected by ground reflections, which may even cause the TOF module to malfunction. Therefore, the present invention provides a new implementation scheme to solve the above problems.

[0051] Refer to the attached figure Figures 1 to 8 As shown, a TOF module for a sweeping robot according to an embodiment of the present invention is illustrated. Specifically, Figure 1 As shown, the sweeping robot 1 includes a sweeping robot body 10 and a TOF module 20, wherein the TOF module 20 is arranged on the side of the sweeping robot body 10 to allow the light projected by the TOF module 20 to be placed below the horizontal line, which helps to identify low-height bottom obstacles such as stairs, feces, etc. through the TOF module 20, thereby facilitating the sweeping robot 1 to achieve the obstacle avoidance function of stairs, feces, etc.

[0052] It is worth noting that since the TOF module 20 is arranged on the side of the sweeping robot body 10, there is no protrusion on the top of the sweeping robot body 10. Therefore, the TOF module 20 will not increase the overall height of the sweeping robot. It is not only easy to carry, but also easy to clean in a lower space (such as the ground under the wardrobe, etc.).

[0053] Further, if Figure 1 and Figure 2 As shown, the TOF module 20 includes a projection module 21 and a receiving module 22, wherein the projection module 21 is used to project an output light field 210 toward an environmental target 30, and the receiving module 22 is used to receive a received light field 220 reflected back by the environmental target 30, wherein the horizontal field angle θ of the projection module 21 is H and vertical field angle θ L The ratio between them is greater than 10, so that the output light field 210 of the projection module 21 has a larger angle in the horizontal direction and a smaller angle in the vertical direction, so as to meet the application scenario of the sweeping robot 1 (that is, a larger ranging range is required in the horizontal direction to determine the surrounding environment, while only a smaller ranging range is required in the vertical direction, and the smaller the better). It can be understood that the received light field 220 of the receiving module 21 is the light field received by the receiving module 22 after the output light field 210 is reflected at the environmental target 30.

[0054] For example, Figure 3 and Figure 4 As shown, the horizontal field of view angle θH of the projection module 21 can be, but is not limited to, implemented as 120°, and the vertical field of view angle θL of the projection module 21 can be, but is not limited to, implemented as 5°, so that the ratio between the horizontal field of view angle and the vertical field of view angle of the projection module 21 is 24. At this time, the output light field 210 of the projection module 21 will form a narrow strip of light spot (i.e., a linear light spot) on the surface of the environmental target 30. Such a large horizontal field of view angle can ensure that the sweeping robot 1 obtains a large horizontal ranging range, while the small vertical field of view angle can effectively prevent the measurement accuracy of the TOF module from being affected by bottom surface reflection.

[0055] It's worth noting that due to the large horizontal field of view of the projection module 21, the diffraction angle of the horizontal edge of the output light field 210 at the environmental target 30 will be very large. This results in the light reflected from the environmental target 30 and returning to the receiving module 22 along the original path being very weak. Therefore, if the light intensity distribution of the output light field 210 projected by the projection module 21 is uniform in the horizontal direction, the light intensity distribution of the received light field 220 received by the receiving module 22 will not be uniform in the horizontal direction and will exhibit a high intensity distribution at the center and low intensity distribution at the edges, which will seriously affect the measurement accuracy and ranging range of the TOF module.

[0056] In order to solve the problem of uneven light intensity distribution of the received light field 220, the present invention designs the light intensity distribution of the output light field 210 of the projection module 21 so as to ensure that the light intensity distribution of the received light field 220 received by the receiving module 22 is relatively uniform as much as possible. Specifically, Figure 3 As shown, the light intensity distribution of the output light field 210 of the projection module 21 in the horizontal direction satisfies Where N = cos m (θ max ), m>1, where θ is the diffraction angle and I is the relative light intensity, so that the receiving module 22 of the TOF module 20 can receive the received light field 220 with a relatively uniform light intensity distribution, which helps to improve the measurement accuracy of the TOF module 20. In other words, the relationship between the relative light intensity I of the output light field 210 in the horizontal direction and the diffraction angle θ satisfies Where N = cos m (θ max ), m>1, so as to ensure that the light intensity distribution of the received light field 220 received by the receiving module 22 is basically relatively uniform, which helps to improve the measurement accuracy of the TOF module 20.

[0057] It is worth noting that the light intensity of the output light field 210 of the projection module 21 is the smallest at the center position in the horizontal direction (the position with a smaller diffraction angle), and the light intensity is the largest at the edge position in the horizontal direction (the position with a larger diffraction angle). This can just compensate for the reflection loss of the environmental target 30 (that is, the reflection loss of the environmental target 30 is smaller at the position with a smaller diffraction angle, and the reflection loss of the environmental target 30 is larger at the position with a larger diffraction angle), so that the receiving module 22 receives the received light field 220 with a basically uniform light intensity distribution.

[0058] Furthermore, considering the limitations of the measurement distance of the TOF module 20 and the uniformity of the received light field 220, in this embodiment of the present invention, Figure 3As shown, the ratio between the maximum value (near the edge of the field of view) and the minimum value (at the center of the field of view) of the light intensity distribution of the output light field 210 in the horizontal direction is greater than or equal to 3, so as to ensure that the TOF module 20 has a sufficient measurement distance while ensuring that the light intensity of the received light field 220 in the horizontal direction is uniformly distributed as much as possible.

[0059] In addition, there will inevitably be a blurred area (i.e., Blur area) at the edge of the output light field 210, and the light intensity of the blurred area of ​​the output light field 210 will decrease from the maximum value of the light intensity distribution of the output light field 210 until it decreases to 1 / e of the light intensity at the starting position of the blurred area. 2 times, the angular range of the blurred region of the output light field 210 is correspondingly defined as the diffraction angle range between the starting position of the blurred region and the position where the light intensity is 1 / e2 times the light intensity at the starting position of the blurred region. Since the light intensity near the starting position in the blurred region is close to the maximum light intensity distribution of the output light field 210, this portion of the light intensity in the blurred region can also be utilized to fully utilize the light energy of the projection module 21, which helps to improve the light energy utilization rate of the TOF module 20. Therefore, in this embodiment of the present invention, the starting position angle of the blurred region of the output light field 210 in the horizontal direction should be less than the maximum field of view angle of the projection module 21.

[0060] For example, the specific light intensity distribution of the output light field 210 of the projection module 21 is as follows: Figure 3 As shown. Figure 3 It can be seen that the horizontal viewing angle of the projection module 21 is 120°, wherein the relationship between the relative light intensity I of the output light field 210 in the horizontal direction and the diffraction angle θ satisfies Where m = 1.73; wherein the ratio between the maximum value (near the edge of the field of view) and the minimum value (at the center of the field of view) of the horizontal light intensity distribution of the output light field 210 is 3, the starting position of the blurred region of the output light field 210 corresponds to the position of ±58°, and the ending position of the blurred region corresponds to the position of ±69°, that is, the angular range of the blurred region of the output light field 210 in the horizontal direction is required to be equal to 11°. In addition, the light intensity at ±62.5° in the blurred region should be no less than 0.7 times the maximum value of the light intensity distribution of the output light intensity 210, so that the light intensity of the blurred region between ±58° and ±62.5° meets the requirements of the receiving module 22, so that a portion of the blurred region in the output light field 210 is utilized, which helps to improve the light energy utilization rate of the TOF module 20. That is to say, the present invention only needs to ensure that the angle at which the light intensity in the blurred area is 0.7 times the maximum value of the light intensity distribution of the output light field 210 is not less than 60° or not greater than -60°, and the angle of the starting position of the blurred area is less than 60° or greater than -60°. In this way, it is possible to ensure that the receiving module 22 obtains sufficient light intensity at the edge position of the receiving light field 220 while also utilizing part of the light energy in the blurred area to improve the light energy utilization rate of the TOF module 20.

[0061] It is worth mentioning that in this embodiment of the present invention, the angular range of the blurred area in the vertical direction of the output light field 210 of the projection module 21 should be no greater than 2°. This prevents the output light field 210 from irradiating the bottom surface due to the excessively large angular range of the blurred area in the vertical direction. This helps prevent the measurement results from being disturbed by stray light reflected from the highly reflective ground. At the same time, the smaller the vertical field angle of the output light field 210 and the smaller the angular range of the blurred area, the more concentrated the total light intensity of the output light field 210, and accordingly, the longer the measurement distance of the TOF module 21 can be.

[0062] For example, the light intensity distribution of the output light field 210 of the projection module 21 in the vertical direction is as follows: Figure 4 As shown. Figure 4 It can be seen that the vertical field of view angle of the projection module 21 is 5°, wherein the starting position of the blurred area of ​​the output light field 210 in the vertical direction corresponds to ±2.5°, and the ending position of the blurred area corresponds to ±3.5, that is, the angular range of the blurred area of ​​the output light field 210 in the vertical direction is equal to 1°, which helps to concentrate the total light intensity of the output light field 210 to increase the measurement distance of the TOF module 21.

[0063] According to the above embodiments of the present invention, Figure 2As shown, the projection module 21 of the TOF module 20 may include a light source module 211 and a diffractive optical element 212, wherein the light source module 211 is used to emit an input light field 2110, and the diffractive optical element 212 is correspondingly arranged in the emission path of the light source module 211, and is used to shape the light intensity distribution of the input light field 2110 to obtain the desired output light field 210. It is understandable that the light intensity distribution form of the input light field 2110 is related to the light source module 211, so here it is only necessary to determine the light intensity distribution form of the output light field 210, and the desired diffractive optical element 212 can be designed through optical design technology. It is understandable that when the input light field 2110 emitted by the light source module 211 and the output light field 210 projected by the projection module 21 are known, various existing technologies can be used to manufacture the corresponding diffractive optical element, and the present invention will not go into details about this. In addition, in this embodiment of the present invention, the light source module 211 may be implemented as, but is not limited to, a vertical cavity surface emitting laser (VCSEL).

[0064] For example, the diffractive optical element 212 may be implemented as, but not limited to, a linear diffuser, wherein the light intensity distribution of the long side of the linear diffuser is as follows: Figure 5 As shown, let the reflection coefficient of the central field of view be R, there are 2m+1 full fields of view, where the fields of view are -m, -(m-1), ...0...(m-1), m. Then for the rth field of view, the corresponding field of view angle θ r , let the tangent angle corresponding to the rth field of view be T r =tanθ r , the corresponding light intensity distribution of the elongated rectangular spot on the object surface is A r (θ), then the integral of the light intensity corresponding to each position of the elongated rectangular light spot is the total power. That is:

[0065]

[0066] Here, P is the total optical power of the light source; ω1 is the light utilization rate introduced by the linear diffuser; V is the vertical width of the object surface; L is the distance from the projection module 21 to the environmental target 30 (i.e., the distance from the environmental target 30 to the receiving module 22); and I is the proportional coefficient of the light intensity distribution of the elongated rectangular light spot at the environmental target 30. This yields the light intensity distribution of each field of view of the elongated rectangular light spot.

[0067] Considering that the projected light spot obeys a certain angular distribution when reflected at the environmental target 30, the angular distribution is set to φ(θ), and considering the relative illumination parameter of the receiving module 22, it is set to RI(θ); then the light intensity distribution A of the elongated rectangular light spot on the environmental target 30 is r (θ) has the following relationship with the light intensity distribution Ir of the received light field 220 of the receiving module 22: r ·Ф(θ)·RI(θ)=I r (θ); that is, the light intensity distribution of the output light field of the linear Diffuser is as follows:

[0068]

[0069] According to the above formula and the relevant information such as the entrance pupil of the receiving module 22, A can be determined r (Center): A r (Edge) ratio relationship is 1:N. When the entrance pupil of the receiving module 22 is 1.27mm, the imaging uniformity and distance measurement results of the receiving module 22 (light energy utilization rate is 80%) are shown in Table 1:

[0070] Table 1: Measurement distance between the center and edge of the linear TOF module

[0071] Center-to-edge ratio 1：5 1：3 1：2.5 Uniformity 0.65 0.338 0.26 Center field of view farthest / nearest distance 4.25m / 12.5cm 4.93m / 14.49cm 5.15m / 15.16cm Edge field of view far / near distance threshold 3.4m / 10cm 2.86m / 8.37cm 2.68m / 7.91cm

[0072] Therefore, according to the actual application requirements, the reasonable uniformity and measurement distance can be determined, and A r (Center): A r (edge) to determine the light intensity distribution of the linear diffuser, that is, to determine the light intensity distribution of the output light field 210 in the horizontal direction.

[0073] In addition, the smaller the field of view angle of the projection module 21 in the vertical direction and the smaller the blurred area, the more concentrated the total light intensity of the output light field 210, and the farther the measurement distance of the TOF module 20 can be. At the same time, the field of view angle of the output light field 210 of the projection module 21 in the vertical direction also needs to consider the influence of stray light caused by the smooth bottom surface emission. Since the TOF module 20 of the present invention is located on the side of the sweeping robot body 10, although the lower edge light of the output light field 210 can be made completely parallel to the horizontal plane in an ideal state to avoid the light of the output light field 210 touching the ground, but considering the errors such as assembly, the lower edge light of the output light field 210 may not be completely parallel to the horizontal plane, which results in that when the measurement distance of the TOF module 20 is large, the light of the output light field 210 will be projected to the ground, so that the surface reflection of the ground will cause some stray light to be reflected into the receiving module 22, thereby interfering with the ranging accuracy and precision of the TOF module 20.

[0074] It is worth noting that Figure 2 As shown, the diffractive optical element 212 of the projection module 21 can also be used to collimate the input light field 2110 emitted by the light source module 211 in the vertical direction, so as to reduce the vertical field angle and the angular range of the blurred area of ​​the output light field 210. Preferably, the vertical field angle of the projection module 21 of the TOF module 20 is no greater than 5°, so as to reserve sufficient installation margin for the TOF module 20 to prevent the output light field projected by the projection module 20 from being reflected by a smooth surface.

[0075] According to this embodiment of the present invention, Figure 2 As shown, the receiving module 22 of the TOF module 20 may include a photosensitive chip 221 and a lens assembly 222, wherein the lens assembly 222 is arranged in the photosensitive path of the photosensitive chip 221, and is used to shape the received light field 220 so that it can be received by the photosensitive chip 221. Specifically, in this embodiment of the present invention, the main light tilt angle CRA_S of the photosensitive chip 221 of the receiving module 22 and the main light tilt angle CRA_L and relative illumination RI of the lens assembly 222 meet the condition: (CRA_S-CRA_L)*RI≥10, so as to ensure that the photosensitive chip 221 can normally sense light and obtain higher image quality.

[0076] It is worth noting that, unlike ordinary imaging module designs, the main light tilt angle of the photosensitive chip 221 of the receiving module 22 of the TOF module 20 of the present invention may not match the main light tilt angle of the lens assembly 222, so that the main light tilt angle of the photosensitive chip 221 and the main light tilt angle of the lens assembly 222 can be adjusted accordingly to improve the relative illumination RI of the lens assembly 222 of the receiving module 22, making the depth perception of the edge field of view more sensitive. In other words, the receiving module 22 of the TOF module 20 of the present invention can compensate the matching between the main light tilt angle of the photosensitive chip 221 and the main light tilt angle of the lens assembly 222 to the relative illumination RI of the lens assembly 222, so as to improve the relative illumination RI of the lens assembly 222, so that the TOF module 20 can be more targeted at the reception of single-wavelength infrared signals, which helps to increase the ranging range of the TOF module 20.

[0077] For example, the main light tilt angle CRA_S of the photosensitive chip 221 of the receiving module 22 of the TOF module 20 can be equal to 30; the main light tilt angle CRA_L of the lens assembly 222 of the receiving module 22 can be equal to 9.4 (such as Figure 6 The relative illumination RI of the lens assembly 222 may be equal to 66.7% (as shown); Figure 7 As shown). In this way, (CRA_S-CRA_L)*RI=13.7>10, so that the receiving module 22 meets the condition: (CRA_S-CRA_L)*RI≥10, so as to greatly improve the relative illumination of the lens assembly 222 and make the depth perception of the edge field of view more sensitive.

[0078] It is worth mentioning that in this embodiment of the present invention, due to the needs of actual work, the single pixel size of the photosensitive chip 221 of the TOF module 20 in the vertical direction is usually on the order of tens of microns. Therefore, from a design perspective, it is possible to sacrifice the image quality in the S direction (corresponding to the vertical direction) to improve the image quality in the T direction (corresponding to the horizontal direction) without pseudo-resolution in the S direction (corresponding to the vertical direction), so as to effectively improve the relative illumination and increase the ranging range of the TOF module 20. In other words, according to the application requirements of the sweeping robot 1, the TOF module 20 needs to accurately measure the depth in the horizontal direction, while the depth measurement accuracy in the vertical direction can be ignored. Therefore, the TOF module 20 can sacrifice the resolution in part of the vertical resolution direction (i.e., the non-key resolution direction), which helps to further improve the relative illumination and further increase the ranging range of the TOF module 20.

[0079] Specifically, if the field resolution of the receiving module 22 of the TOF module 20 at 1 Nyquist frequency in the horizontal resolution direction is recorded as MTF@in; the field resolution of the receiving module 22 at 1 Nyquist frequency in the vertical resolution direction is recorded as MTF@unin; and the relative illumination value of 1 field is RI, then the receiving module 22 of the TOF module 20 needs to satisfy the relationship: (100*MTF@unin) / (MTF@in*RI)≤3, so that the resolution in the vertical resolution direction (i.e., the non-key resolution direction) is compensated to the horizontal resolution direction (i.e., the key resolution direction).

[0080] Exemplarily, when the receiving module 22 of the TOF module 20 has a field resolution MTF@in of 45.1% at 1 Nyquist frequency in the horizontal resolution direction; a field resolution MTF@unin of 0.62% at 1 Nyquist frequency in the vertical resolution direction, and relative illumination RI of 66.7%, (100*MTF@unin) / (MTF@in*RI)=2.06, satisfying the relationship: (100*MTF@unin) / (MTF@in*RI)≤3.

[0081] Furthermore, the receiving module 22 of the TOF module 20 also satisfies the relationship: f(MTF>0.5) / (l*n)≥1.0, where f(MTF>0.5) is the spatial frequency corresponding to the receiving module 22 having a horizontal resolution MTF of 1 field of view greater than 0.5, l is the total length of the lens assembly 222, and n is the number of lenses in the lens assembly 222. This allows the number of lenses in the lens assembly 222 to be reduced while maintaining resolution, thereby helping to reduce the overall size of the receiving module 22.

[0082] For example, Figure 8 As shown, when the number of lenses of the receiving module 22 of the TOF module 20 is n=3 and the total length l=10 mm, the spatial frequency f(MTF>0.5) corresponding to the field resolution MTF>0.5 of the receiving module 22 in the key resolution direction l is 36, and at this time f(MTF>0.5) / (l*n)=1.2, satisfying the relationship f(MTF>0.5) / (l*n)≥1.0, where n is the number of lenses of the lens assembly 222, and l is the total length of the lens assembly 222.

[0083] Those skilled in the art will appreciate that the embodiments of the present invention described above and shown in the accompanying drawings are intended to be illustrative only and are not intended to limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and illustrated in the embodiments. Any variations or modifications may be made to the embodiments of the present invention without departing from the principles described.

Claims

1. A TOF module for a sweeping robot, characterized in that: include: a projection module, wherein the projection module is suitable for being provided on the main body of the sweeping robot, and is used to project an output light field, wherein the ratio of the angle of the output light field in the horizontal direction to the angle in the vertical direction is greater than 10; and a receiving module, wherein the receiving module is suitable for being correspondingly arranged on the cleaning robot body, and is used to receive the reflected receiving light field; The receiving module includes a photosensitive chip and a lens assembly, wherein the lens assembly is correspondingly arranged in the photosensitive path of the photosensitive chip for shaping the received light field, wherein the photosensitive chip and the lens assembly satisfy the condition: (CRA_S-CRA_L)*RI≥10, wherein CRA_S is the main light inclination angle of the photosensitive chip, CRA_L is the main light inclination angle of the lens assembly, and RI is the relative illumination of the lens assembly.

2. The TOF module for a sweeping robot according to claim 1, wherein: The projection module is suitable for being installed on the side of the cleaning robot body, and the receiving module is suitable for being installed on the side of the cleaning robot accordingly.

3. The TOF module for a sweeping robot according to claim 1, wherein: The light intensity distribution of the output light field of the projection module in the horizontal direction satisfies Where N = cos m (θ max ), m>1; where θ is the diffraction angle and I is the relative light intensity.

4. The TOF module for a sweeping robot according to claim 2, wherein: The light intensity distribution of the output light field of the projection module in the horizontal direction satisfies Where N = cos m (θ max ), m>1; where θ is the diffraction angle and I is the relative light intensity.

5. The TOF module for a sweeping robot according to claim 4, wherein: The ratio between the maximum value and the minimum value of the light intensity distribution of the output light field in the horizontal direction is not less than 3.

6. The TOF module for a sweeping robot according to claim 5, wherein: The starting position angle of the blurred area of ​​the output light field in the horizontal direction is smaller than the maximum horizontal field angle of the projection module.

7. The TOF module for a sweeping robot according to claim 6, wherein: The angular range of the blurred area of ​​the output light field in the vertical direction is no greater than 2°.

8. The TOF module for a sweeping robot according to claim 7, wherein: The light intensity distribution of the output light field of the projection module in the horizontal direction satisfies Where m = 1.

73.

9. The TOF module for a sweeping robot according to any one of claims 1 to 8, wherein: The projection module includes a light source module and a diffractive optical element, wherein the diffractive optical element is arranged in the emission path of the light source module and is used to shape the input light field emitted by the light source module to form the output light field.

10. The TOF module for a sweeping robot according to claim 9, wherein: The diffractive optical element of the projection module is further used to collimate the input light field emitted by the light source module in a vertical direction.

11. The TOF module for a sweeping robot according to claim 1, wherein: The receiving module satisfies the relationship: (100*MTF@unin) / (MTF@in*RI)≤3, where MTF@in is the field resolution of the receiving module at 1 Nyquist frequency in the horizontal resolution direction, MTF@unin is the field resolution of the receiving module at 1 Nyquist frequency in the vertical resolution direction, and RI is the relative illumination of the lens assembly.

12. The TOF module for a sweeping robot according to claim 11, wherein: The spatial frequency f(MTF>0.5) corresponding to the horizontal resolution of the receiving module 1 field of view resolution MTF>0.5 and the number of lenses n of the lens assembly satisfy the relationship: f(MTF>0.5) / (l*n)≥ 1.0, where l is the total length of the lens assembly.

13. A sweeping robot, characterized in that: include: A sweeping robot body; and The TOF module according to any one of claims 1 to 12, wherein the TOF module is mounted on a side of the sweeping robot body.

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