Line obstacle identification method based on line laser

Abstract

The invention discloses a line obstacle recognition method based on line laser, and the method comprises the steps: 1, controlling a line laser sensor to emit line laser in a walking process of a robot in a navigation direction, and sequentially collecting two frames of line laser data formed by the reflection of the line laser through the surface of a to-be-measured object; 2, the robot recognizes the surface of the object to be measured as the existence of a linear obstacle in combination with the laser slope in each frame of line laser data collected in the step 1 and the size relation between the number of repeated angles and the total number of occupied angles; wherein the number of the repetitive angles and the total number of the occupied angles are obtained by counting the condition of the repetitive occupied angles of the obstacle points in the two frames of line laser data sequentially collected in the step 1. And the accuracy of the robot for identifying the line obstacles on the ground by using the line laser is improved.

Description

Technical Field

[0001] The present application relates to the field of line laser technology, and in particular to a line obstacle recognition method based on line laser. Background Art

[0002] Most of the methods of using line laser obstacle avoidance in the prior art require detecting the height of the obstacle. For example, among the multiple laser points scanned by the line laser, as long as the height of the laser point is higher than 20mm, it is considered that an ordinary obstacle is detected, triggering the robot to take obstacle avoidance actions. Low obstacles include linear obstacles. Generally, the main characteristics of linear obstacles are short (generally not higher than 20mm), continuous, and twisted. In the scene where linear obstacles are identified by line laser, if linear obstacles such as wires, network cables, and charging cables are twisted to form stacked lines, they are identified as objects of greater height by the line laser sensor, resulting in misjudgment. In addition, when the prior art may use multiple frames of line laser data to jointly detect low obstacles, each time an additional frame of data is saved for comparison, the amount of calculation and storage will increase, and the distance the robot needs to walk will also increase a lot, which may cause the robot to cross low obstacles. In this way, when the sweeping robot is cleaning the ground and there are linear obstacles, such as electrical wires, mobile phone charging cables and other linear obstacles laid flat on the cleaning ground, the height of the linear obstacles laid flat on the cleaning ground is very low, and it is generally not easy for the robot to directly use the height information to identify them as ropes, causing the sweeping robot to directly cross over the unidentified linear obstacles such as ropes, and the ropes and other linear obstacles will then be entangled in the wheels, main brush, side brush and other parts of the sweeping robot, making it impossible for the sweeping robot to work normally. Summary of the invention

[0003] This application discloses a linear obstacle recognition method based on linear laser, and the specific technical solution is as follows: A linear obstacle recognition method based on a linear laser, wherein a linear laser sensor is installed on the front side of the robot body; the linear obstacle recognition method comprises: step 1, when the robot is walking along the navigation direction, the linear laser sensor is controlled to emit a linear laser, and two frames of linear laser data formed by the reflection of the linear laser on the surface of the object to be measured are collected in sequence; step 2, in combination with the laser slope in each frame of the linear laser data collected in step 1, and the size relationship between the number of repeated angles and the total number of occupied angles, the robot identifies the surface of the object to be measured as having linear obstacles; wherein the number of repeated angles and the total number of occupied angles are obtained by counting the repeated occupation angles of the obstacle points in the two frames of linear laser data collected in sequence in step 1. The present application identifies the linear obstacles in combination with the laser slope in each frame of the linear laser data collected in step 1, and the size relationship between the number of repeated angles and the total number of occupied angles, avoids misidentification as interference from other types of obstacles, and improves the accuracy of the robot using a linear laser to identify linear obstacles on the ground. Moreover, considering the amount of calculation and the walking distance of the robot, only two frames of line laser data collected sequentially are used to detect the linear obstacles, which saves the amount of calculation and prevents the robot from being entangled and stuck by linear obstacles before the type of obstacle is accurately identified due to the large walking distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 This is a flowchart of a linear obstacle recognition method based on line laser disclosed in an embodiment of the present application.

[0005] Figure 2 An embodiment of the present application discloses a schematic diagram of a detection area 103 of a line laser sensor 102 in front of a robot 101 and a preset detection angle range (angle AOB with the center O of the robot body as the vertex) of the line laser sensor 102 .

[0006] Figure 3 An embodiment of the present application discloses a scenario in which a robot walks toward a step-like obstacle 105 and when the robot walks to a first position along a navigation direction OP, a schematic diagram of a line laser being projected onto the step-like obstacle 105 .

[0007] Figure 4 An embodiment of the present application discloses a scenario in which a robot walks toward a step-like obstacle 105 and when the robot walks to a second position along a navigation direction OP, a schematic diagram of a line laser being projected onto the step-like obstacle 105 .

[0008] Figure 5 An embodiment of the present application discloses a scenario in which a robot walks toward a linear obstacle 106 and when the robot walks to a first position along a navigation direction OP, a schematic diagram of a line laser being projected onto the linear obstacle 106 .

[0009] Figure 6 An embodiment of the present application discloses a scenario in which a robot walks toward a linear obstacle 106 and when the robot walks to a second position along a navigation direction OP, a schematic diagram of a line laser being projected onto the linear obstacle 106 .

[0010] Figure 7 An embodiment of the present application discloses a robot in Figure 5 A frame of line laser data collected in Figure 6 Schematic diagram of logical processing of a frame of line laser data collected in accordance with the observation angle ranges divided in sequence within the preset detection angle range.

[0011] Figure 8 yes Figure 1 A flowchart of the execution method of step 2 in the disclosed linear obstacle recognition method. Implementation

[0012] The technical solutions in the embodiments of the present application will be described in detail below in conjunction with the drawings in the embodiments of the present application. To further illustrate the embodiments, the present application provides drawings. These drawings are part of the disclosure of the present application, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in this field should be able to understand other possible implementations and advantages of the present invention.

[0013] In the description of this application, the directions or positional relationships of "left", "right", "up", "down", "clockwise", and "counterclockwise" are based on the attached Figure 2 To Attachment Figure 7 It should be understood that the orientation or positional relationships shown are only for the convenience of describing the present application 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, and therefore should not be understood as a limitation on the present application.

[0014] As an embodiment, a linear obstacle recognition method based on line laser is disclosed. The execution subject of the linear obstacle recognition method is a robot. A line laser sensor is installed on the front side of the robot body. The robot can be a sweeping robot and can have any suitable shape, such as a more traditional round body, a D-shaped body or a rectangular body. The robot is used to control the line laser sensor to emit a line laser to the surface of the object to be measured during walking. The line laser forms a light strip on the surface of the object to be measured; the light strip at the same position is reflected to form a frame of line laser data, and a frame of line laser data is line laser data at each angle within a preset detection angle range; the line laser sensor is used to collect line laser data within the preset detection angle range.

[0015] like Figure 1As shown, the linear obstacle recognition method includes: Step 1: When the robot walks along the navigation direction, the line laser sensor is controlled to emit a line laser, and two frames of line laser data formed by the line laser reflected from the surface of the object to be measured are collected in sequence, and then step 2 is performed. The installation direction of the line laser sensor relative to the center of the body is parallel to the navigation direction. When the navigation direction is set to be parallel to the central axis of the body, the line laser sensor is installed on the front side of the robot body along the central axis of the body. The line laser sensor emits a line laser to the surface of the object to be measured, and the surface of the object to be measured reflects to form a light strip, which forms a corresponding bright section. It can be regarded as composed of projected light spots (i.e., laser spots) of multiple laser beams. The extension direction of the light strip formed on the horizontal ground is set perpendicular to the navigation direction. In some embodiments, the light strip formed by the line laser sensor emitted to the surface of the object to be measured is regarded as being separated on the left and right sides of the central axis of the body (equivalent to being parallel to the navigation direction OP), which can be intersecting, parallel or partially overlapping. The specific distribution form varies depending on the contour shape of the obstacle protruding from the ground.

[0016] Start the line laser sensor, Figure 2 This is a schematic diagram of an embodiment of the present application that discloses a detection area 103 of a line laser sensor 102 in front of a robot 101 and a preset detection angle range (angle AOB with the center O of the body as the vertex) of the line laser sensor 102; within the detection range 103, a line segment 104 is a light bar AB formed in front of the robot by the line laser emitted by the line laser sensor. The installation direction of the line laser sensor 102 relative to the center O of the body is parallel to the navigation direction OP, and the navigation direction OP is perpendicular to the light bar AB.

[0017] For the line laser sensor, the emission angle of the line laser can be 15 degrees, 30 degrees, 45 degrees, 60 degrees, etc. from the horizontal direction. This embodiment does not limit the angle obliquely downward from the walking direction or the value of the emission angle of the line laser. The line laser emitter is configured to illuminate a width area larger than the width of the robot, forming a bright section or a light strip on the surface of the object to be measured. Because some obstacle points protrude from the ground, the projected light strip may not be a straight line or a continuous curve relative to the ground, and there may be a disconnected position, resulting in a discontinuous light strip.

[0018] In the robot, the line laser sensor is also used to collect laser points formed by the reflection of the line laser on the surface of the object to be measured. In essence, the infrared camera collects images of laser points formed by the reflection of the line laser on the surface of the object to be measured, covering all or part of the image of the environment illuminated by the line laser; the infrared camera captures and records multiple frames of line laser data per second, preferably 33 frames per second, and each frame of line laser data includes approximately 120 laser points, and each laser point includes three types of posture data: angle, distance, and height.

[0019] When the robot walks along the navigation direction, the position where the robot is located when collecting the first frame of line laser data is marked as the first position, and the position where the robot is located when collecting the second frame of line laser data is marked as the second position. When the robot walks from the first position to the second position along the navigation direction, the distance between the robot and the surface of the object to be measured becomes smaller. The prior art may use multiple frames (more than two frames) of line laser data to jointly detect low obstacles. Every time an additional frame of data is saved for comparison and matching, the amount of calculation and storage increases, and the distance the robot needs to walk will also increase a lot, resulting in the robot crossing the line obstacle before it has time to identify the line obstacle, resulting in entanglement problems. In this embodiment, two frames of line laser data can be continuously collected.

[0020] Step 2. Combined with the laser slope in each frame of line laser data collected in step 1, and the relationship between the number of repeated angles and the total number of occupied angles, the robot identifies the surface of the object to be measured as having linear obstacles. Linear obstacles include entangled obstacles such as electric wires, network cables, and charging cables, and are placed horizontally on the walking surface of the robot in a curved and uneven form. They are generally not straight. The height of the linear obstacles to be identified in this embodiment is preferably less than the height threshold of the traversable obstacle (less than the installation height of the linear laser sensor in the robot), and are low obstacles; but it is necessary to avoid the linear obstacles by identifying the linear obstacles.

[0021] In the two frames of line laser data collected sequentially, the number of repeated angles and the total number of occupied angles are obtained by counting the repeated occupied angles of obstacle points in the two frames of line laser data collected sequentially in step 1.

[0022] This embodiment first determines the direction characteristics of the laser slope in each frame of line laser data, and then uses the repeated angles occupied by laser points in two frames of line laser data collected successively to identify the linear obstacles on the surface of the object to be measured and eliminate the interference of step obstacles, wherein the step obstacles include round stick-type short steps, square short steps and other obstacles (round stick-type short steps can be guide rails or sliding door rails, and square short steps can be door steps). The contour height distribution characteristics reflected from the surface of the short step identified by the robot walking along a specific oblique direction relative to the short step are relatively similar, and the step-type obstacles are easily mistakenly identified as the linear obstacles.

[0023] In this embodiment, in the required identification of the surface of the object to be measured, it is necessary to distinguish between regular crossable obstacles and winding and continuous ropes (which belong to linear obstacles). In order to reduce the misjudgment problem caused by the single comparison and analysis of the height information of the laser point, this embodiment can distinguish between linear obstacles and wall obstacles based on the number of obstacle points that appear repeatedly at the same angle in two frames of line laser data. Moreover, this is performed during the walking process of the robot. The line laser detects two different areas of the surface of the object to be measured at the same position as the walking position of the robot changes. For example, in two frames of line laser data collected sequentially, the first frame of line laser data reflects the contour within a part of the angle interval of the linear obstacle, and the second frame of line laser data reflects the contour within another part of the angle interval of the linear obstacle. There are repeatedly detected contours in the two parts of the angle interval. Therefore, the obstacle points that appear repeatedly at the same angle are located in the overlapping area of ​​the two different areas. In this embodiment, the number of repeated angles can be expressed by the laser points in the two frames of line laser data collected sequentially and repeatedly occupying angles; preferably, the more the number of obstacle points that appear repeatedly at the same angle, the larger the size of the obstacles on the surface of the object to be measured, including the larger the contour surface and the larger the height. For example, large obstacles such as wall obstacles need to be eliminated first. Therefore, after obtaining the number of repeated angles and the total number of occupied angles, while determining the laser slope in each frame of line laser data, the size relationship between the number of repeated angles and the total number of occupied angles is determined, so that the number of repeated angles obtained is reasonable, at least the size is reasonable and not too large relative to the total number of occupied angles. It can be determined that the height of the laser points in the two frames of line laser data collected sequentially is the obstacle height that the robot is allowed to cross, and it is further determined that there are linear obstacles such as zigzag ropes on the surface of the object to be measured.

[0024] To sum up, in this embodiment, the laser slope in each frame of line laser data collected in step 1 and the relationship between the number of repeated angles and the total number of occupied angles are combined to identify the linear obstacles, avoid misidentification as other types of obstacle interference, and improve the accuracy of the robot using line laser to identify linear obstacles on the ground.

[0025] The main characteristics of the linear obstacles are that they are short (generally not higher than 20 mm), continuous, and curved to the horizontal ground. If the height characteristics of the laser point are directly used for identification, the height is small and the light strip formed by the linear laser emission is straight, which is not enough to form an obvious recognition effect at one time. Therefore, this embodiment only uses two frames of linear laser data collected in sequence to detect the linear obstacles based on the consideration of the calculation amount and the walking distance of the robot, which saves the calculation amount and prevents the robot from being entangled and stuck by the linear obstacles before the type of obstacle is accurately identified due to the excessive walking distance.

[0026] As an embodiment, in step 2, the robot identifies the surface of the object to be measured as having a linear obstacle by combining the laser slope in each frame of line laser data collected in step 1 and the relationship between the number of repeated angles and the total number of occupied angles, such as Figure 8 As shown, including: Step 21, when the robot detects that there are two laser slopes with different directions in at least one frame of line laser data, step 22 is executed; that is, when the robot determines that the lines connecting the laser points in at least one frame of line laser data show an ascending laser slope and a descending laser slope, step 22 is started to identify the linear obstacles, the main characteristics of which are short (generally not higher than 20 mm), continuous, and curved to the horizontal ground, so as to exclude obstacles in which the laser point lines formed by reflection have and only produce a laser slope with one direction.

[0027] Step 22, counting the number of observation angle ranges repeatedly occupied by the obstacle points marked in the two frames of line laser data collected in sequence, obtaining the number of repeated angles, between the two frames of line laser data collected in sequence, the observation angle ranges repeatedly occupied are counted only once, so as to screen out obstacle points in the angle repetition area in the two frames of line laser data; and counting the number of observation angle ranges not repeatedly occupied by the obstacle points marked in the two frames of line laser data collected in sequence, obtaining the total number of occupied angles; extracting obstacle points occupying different observation angle ranges from the two frames of line laser data, and determining that the number of repeated angles and the total number of occupied angles are both obtained by counting the angles repeatedly occupied by the obstacle points in the two frames of line laser data collected in sequence in step 1; and then executing step 23. Among them, the robot marks the laser points in each frame of line laser data whose height is greater than the reference height as obstacle points, and the robot does not mark the laser points in each frame of line laser data whose height is less than or equal to the reference height as obstacle points.

[0028] It should be noted that in this embodiment, the robot marks the laser points in each frame of line laser data whose height is greater than the reference height as obstacle points, which can be recognized by the robot as obstacles and need to be decided whether to cross them to prevent collision or entanglement. The robot does not mark the laser points in each frame of line laser data whose height is less than or equal to the reference height as obstacle points. The laser points whose height is less than or equal to the reference height can be recognized by the robot as ground point clouds, allowing the robot to directly cross them and regard them as horizontal ground. The reference height is preferably 2mm.

[0029] The observation angle range represents the angle feature of a laser point falling into the laser coordinate system, forming an azimuth angle range relative to the center of the robot body that covers the corresponding obstacle contour, located at Figure 2 The angle AOB is within the range and can be used Figure 7 A row of squares in represents. Figure 7 As shown, the squares in the first row represent the situation where the laser points occupying various observation angle ranges in the first frame line laser data are marked as obstacle points, and the squares in the second row represent the situation where the laser points occupying various observation angle ranges in the second frame line laser data are marked as obstacle points. The squares filled with black in the first row and the second row are aligned, and the squares filled with black in the third row represent the observation angle ranges occupied by the laser points marked as obstacle points that are extracted non-repeatedly from the first frame line laser data and the second frame line laser data, corresponding to Figure 7 The total number of occupied angles obtained in is equal to the value 20; the black filled squares in the fourth row represent the observation angle range occupied by the laser points marked as obstacle points in the angle repetition area in the first frame line laser data and the second frame line laser data, corresponding to Figure 7 The number of repetition angles obtained is equal to a value of 5.

[0030] Step 23. Based on the relationship between the number of repeated angles and the total number of occupied angles, the robot identifies the surface of the object to be measured as having linear obstacles. This embodiment uses the angle number information in two frames of line laser data to obtain the number of repeated angles and the total number of occupied angles. Based on this, walls or other large obstacles can be preferentially identified when the number of repeated angles and / or the total number of occupied angles are too large, because this type of large obstacle will occupy a larger angle range in two frames of line laser data (not limited to whether it is repeatedly occupied).

[0031] It should be noted that the rope (a linear obstacle) is very low when placed on the ground, and the laser point connection line formed by the projection is tortuous, which is not very obvious, and is not enough to directly use the laser point connection feature for direct judgment. Otherwise, the recognition result generated is consistent with the obstacle, rather than the linear obstacle; in addition, the linear obstacles such as electric wires, network cables, and charging cables are twisted and can be stacked to a height higher than 20mm. They are not recognized as low obstacles, that is, they are not recognized as obstacles or linear obstacles. Therefore, the height or the laser slope formed by the laser point connection line is not directly used for the identification of obstacles. Therefore, it is necessary to use steps 21 to 23 for multi-gradient screening before formally identifying linear obstacles.

[0032] The linear obstacles identified in this embodiment are mainly lines lying across the floor, which need to be judged by combining the previous and next two frames of line laser data, specifically by utilizing the characteristics of linear obstacles being continuous, curved and flat. For example, when the robot walks along the navigation direction at a certain distance step, it collects the first frame of line laser data when it moves to the first position, and extracts a part of the rope. After moving a distance step, it reaches the second position and collects the second frame of line laser data, and extracts other parts of the rope. The two parts extracted successively by the robot have overlapping angle areas and non-overlapping angle areas, which serve as the angle range basis for determining the relationship between the number of repeated angles and the total number of occupied angles. In summary, on the basis of determining the direction characteristics of the laser point connection line of the two frames of line laser data, the linear obstacles are identified by utilizing the relationship between the number of repeated angles and the total number of occupied angles.

[0033] As an embodiment, in step 23, according to the magnitude relationship between the number of repeated angles and the total number of occupied angles, the method in which the robot identifies the surface of the object to be detected as having linear obstacles includes: When the total number of occupied angles is greater than or equal to the first preset observation angle number threshold, and the number of repeated angles is less than the ratio of the total number of occupied angles to the preset reduction coefficient, the robot identifies the surface of the object to be measured as having linear obstacles, and determines that the height of each laser point in the two frames of line laser data collected in sequence is less than or equal to the surmountable obstacle height threshold, wherein the reference height is less than the surmountable obstacle height threshold, the surmountable obstacle height threshold is less than the installation height of the line laser sensor in the robot, the surmountable obstacle height threshold is preferably 20mm, the reference height is preferably 2mm, and the installation height of the line laser sensor in the robot is preferably 45mm. Thus, in the two frames of line laser data collected in sequence, the relationship between the number of repeated angles and the total number of occupied angles is used to exclude high obstacles such as walls.

[0034] It should be noted that, in the present embodiment, it is necessary to distinguish between regular crossable obstacles and winding and continuous ropes (which belong to line obstacles) in the surface of the object to be measured that needs to be identified. In order to reduce the misjudgment problem caused by comparing and analyzing the height information of the laser point alone, in the present embodiment, based on the detection of two laser slopes with different directions in at least one frame of line laser data in step 21, the number of obstacle points that repeatedly occupy the same observation angle range in the two frames of line laser data is combined to eliminate the influence of wall obstacles. Moreover, this is performed during the walking process of the robot. The line laser detects two different areas of the surface of the object to be measured at the same position as the walking position of the robot changes. For example, in two frames of line laser data collected sequentially, the first frame of line laser data reflects the contour within a part of the angle interval of the surface of the object to be measured, and the second frame of line laser data reflects the contour within another part of the angle interval of the surface of the object to be measured. There are repeatedly detected contour lines in the two parts of the angle interval.

[0035] In this embodiment, the number of repeated angles can be expressed by using the situation that the laser points in the two frames of line laser data collected sequentially repeatedly occupy angles; corresponding to the step 22, the number of repeated angles and the total number of occupied angles are the results of logical analysis and processing of the number of obstacle points in the two frames of line laser data, so as to respectively extract the number of angles repeatedly occupied by the obstacle points in the two frames of line laser data collected sequentially and the number of angles occupied by each obstacle point individually, and by setting the preset reduction coefficient and the first preset observation angle number threshold, the number of repeated angles and the total number of occupied angles are limited to the corresponding numerical range.

[0036] In this embodiment, the more obstacle points that appear repeatedly at the same angle, the larger the size of the obstacles on the surface of the object to be measured, including the larger the contour surface and the larger the height. For example, large obstacles such as wall obstacles need to be eliminated first. Therefore, after obtaining the number of repeated angles and the total number of occupied angles, it is determined whether the total number of occupied angles is greater than or equal to the first preset observation angle number threshold, and it is also determined whether the number of repeated angles is less than the ratio of the total number of occupied angles to the preset reduction coefficient, so as to determine whether the linear obstacles are identified, determine the change characteristics of the laser points in the two frames of line laser data reflected from the surface of the object to be measured as the robot walks, and then determine the height distribution characteristics of the laser points in the two frames of line laser data collected sequentially and the distribution characteristics of the obstacle contours where they are located, so as to improve the accuracy of the linear obstacles.

[0037] As an embodiment, the linear obstacle identification method further includes: in a frame of linear laser data collected in step 1, if it is detected that the number of observation angle ranges occupied by the laser point is greater than or equal to the second preset observation angle number threshold, and the number of observation angle ranges occupied by the laser point is less than or equal to the third preset observation angle number threshold, then the frame of linear laser data collected in step 1 is marked as a legal data frame; if two frames of legal data frames are collected in sequence, then the two frames of legal data frames are marked as two frames of linear laser data collected in sequence required to obtain the number of repeated angles and the total number of occupied angles. The detection operation in this embodiment can be selected to be implemented before executing step 21, so that before the number of relevant observation angle ranges is formally counted in step 21, it is necessary to confirm whether the two frames of linear laser data collected in sequence in step 1 are legal through the information on the number of angles occupied by the obstacle points.

[0038] Specifically, the second preset observation angle number threshold is less than the first preset observation angle number threshold, which means that the number of observation angle ranges occupied by obstacle points in a frame of line laser data is too small and obviously not the line obstacle or the step obstacle; the first preset observation angle number threshold is less than the third preset observation angle number threshold, of course, the number of observation angle ranges occupied by obstacle points in a frame of line laser data is too large and obviously not the line obstacle, for example, the outline of a rope laid on the ground detected by the line laser generally does not occupy a large angle range of a frame. Therefore, in a frame of line laser data collected in step 1, if the number of observation angle ranges occupied by obstacle points detected is greater than or equal to the second preset observation angle number threshold, and the number of observation angle ranges occupied by obstacle points is less than or equal to the third preset observation angle number threshold, then the frame of line laser data collected in step 1 is marked as a legal data frame; further, if two frames of legal data frames are detected successively, the two frames of legal data frames are marked as two frames of line laser data required to be collected to count the number of repeated angles and the total number of occupied angles; wherein, the legal data frames detected successively can be two frames of line laser data collected in sequence in step 1. Then, the two frames of legal data are updated to the two frames of line laser data collected in sequence in step 21, and step 21 is executed again. Illegal data frames are excluded in advance, the processing amount of line laser data is reduced, and the recognition accuracy of the linear obstacle is improved.

[0039] As an embodiment, the robot divides the preset detection angle range of the line laser sensor into the number of observation angle ranges for target detection according to the predetermined clock direction; between two observation angle ranges divided successively, the maximum angle value of the first observation angle range is the minimum angle value of the second observation angle range. In this embodiment, for the same frame of line laser data, each observation angle range remains unchanged while the robot walks along the navigation direction, and the angle between the same position on the surface of the object to be measured and the center of the gradually approaching body changes as the robot approaches the surface of the object to be measured, and the observation angle range is set in advance relative to the center of the body.

[0040] Figure 2 This is a schematic diagram of an embodiment of the present application that discloses the detection area 103 of the line laser sensor 102 in front of the robot 101 and the preset detection angle range of the line laser sensor 102. The preset detection angle range is the angle AOB with the center O of the body as the vertex, which can be symmetrical about the navigation direction OP, that is, the angle of the angle AOP is equal to the angle of the angle BOP; within the detection range 103, the line segment 104 is the light bar AB formed in front of the robot by the line laser emitted by the line laser sensor; the preset detection angle range (angle AOB with the center O of the body as the vertex) is preferably 60 degrees. In the process of the robot walking along the navigation direction OP, the length of the light bar 104 in the vertical direction of the navigation direction OP does not change, and the angle value of the angle AOB does not change.

[0041] If the angle where the ray OP is located is set to 0 degrees and measured in a counterclockwise direction, starting from the middle, the angle range of the left half of the angle AOB is from 0 to 30 degrees, and the angle range on the right is from 330 degrees to 360 degrees and then back to 0 degrees (360 degrees). The preset detection angle range is the line laser coverage angle formed relative to the body center O of the robot to cover the laser point at the corresponding angle, not the angle formed relative to the line laser sensor 102. However, there is a large amount of angle conversion in the calculation and detection of the two angle ranges from 0 to 30 degrees and from 330 to 360 degrees. Therefore, in this embodiment, the preset detection angle range is divided into target detection number observation angle ranges according to the established clockwise direction. For example, the established clockwise direction is preferably counterclockwise, the preset detection angle range is 60 degrees, the target detection number is preferably 60, and the angle span of each observation angle range is 1 degree. According to the counterclockwise direction, the 60-degree angle AOB is divided into 60 observation angle ranges from right to left, and the observation angle ranges formed by 0 to 1 degree, 1 to 2 degrees, 2 to 3 degrees, ..., 59 to 60 degrees are measured in turn. It can be understood that the angle step required for measurement is 1 degree; then there are 120 laser points in a frame of line laser data collected by the line laser sensor, and the 120 laser points can be distributed in 60 observation angle ranges, and at least 1 laser point falls into one observation angle range.

[0042] According to the division rule of the observation angle range within the preset detection angle range, an array can be established, and each element of the array indicates whether the corresponding observation angle range is occupied by an obstacle point. After the laser points falling into the corresponding observation angle range are selected as the laser points occupying the corresponding observation angle range, their angle values ​​are rounded.

[0043] In a frame of line laser data, whenever there is a laser point with a height greater than 2 mm, the robot configures the obstacle mark logic information corresponding to the laser point to logic 1 and marks the laser point as an obstacle point, so that the robot knows the number of obstacle points in a frame of line laser data.

[0044] Corresponding to Figure 7 In the embodiment, an observation angle range is represented by a square in a row where frame1 or frame2 is located, and the laser points occupying the corresponding observation angle range can also be understood as the laser points occupying the square. In some embodiments, the observation angle range of 0 degree to 1 degree is represented by a square in a row where frame1 or frame2 is located. Figure 7The obstacle point is represented by the leftmost square in the row where frame1 or frame2 is located; the obstacle point is represented by a black-filled square in the row where frame1 or frame2 is located. A square can be understood as a bit in a frame of line laser data, so as to facilitate logical calculation using obstacle marking logic information.

[0045] Figure 7 The squares in each column represent the observation angle range of the same angle value; there are 60 squares in each row, representing 60 observation angle ranges; the marking of the squares in the row where frame1 is located reflects Figure 5 The obstacle marking situation generated by the line laser sensor detecting the line obstacle 106, and the marking situation of the squares in the row where frame2 is located reflects Figure 6 The obstacle marking situation generated by the line laser sensor detecting the line obstacle 106 is obvious. The number of black filled squares in the row where frame2 is located is more than that in the row where frame1 is located, especially on the right side of a row of squares. Figure 6 The distribution characteristics of the longer black bold rectangle on the right side of the middle light strip 104 are consistent, thereby generating a longer light spot deviation phenomenon.

[0046] It should be noted that the multiple laser points collected by the line laser sensor generally fall into an observation angle range. Note that the prior art uses "fall into" to indicate the angular distribution characteristics of the laser points, while the present application uses "occupy" to indicate that a laser point occupies an observation angle range, or is understood as a laser point occupying / falling into an observation angle. Specifically, the present embodiment selects a laser point with the smallest angle value from the multiple laser points that fall into the current observation angle range and configures it as the laser point occupying the current observation angle range. In a scenario where the 120 laser points in a frame of line laser data are distributed in a range of 60 observation angles, the points are rotated counterclockwise. Figure 2The angle AOB shown is configured to be in the range of 0 to 60 degrees and the angle step of each observation angle range is 1 degree. Assuming that there are three laser points "falling into" the observation angle range of 1 to 2 degrees, they "fall into" 1.2 degrees, 1.4 degrees, and 1.8 degrees respectively. When the present embodiment traverses to the laser point at 1.2 degrees in the counterclockwise direction, the laser point at 1.2 degrees is regarded as the laser point occupying the observation angle range of 1 to 2 degrees, and can also be regarded as the representative point at the observation angle of 1 degree (correspondingly, it can be regarded as dividing the preset detection angle range into 60 observation angles), and the laser points at angles 1.4 and 1.8 with larger angle values ​​"falling into" the observation angle range of 1 to 2 degrees are ignored in the present embodiment and are not regarded as occupying the observation angle range of 1 to 2 degrees. Therefore, the obstacle points marked in the same frame line laser data are configured not to repeatedly occupy the same observation angle range, so that only one obstacle point is marked in one observation angle range.

[0047] As an embodiment, in step 22, the number of observation angle ranges repeatedly occupied by obstacle points marked in two frames of linear laser data collected sequentially is counted, and the method for obtaining the number of repeated angles includes: The robot divides the two frames of line laser data collected in sequence into a frame of line laser data collected previously and a frame of line laser data collected currently; for each frame of line laser data, the robot divides the preset detection angle range of the line laser sensor into the number of observation angle ranges for target detection in advance according to the established clock direction, and the angle step involved in each observation angle range is equal; in the same frame of line laser data, each observation angle range remains unchanged while the robot walks along the navigation direction; a laser point with the smallest angle value is selected from multiple laser points falling into the current observation angle range and configured as the laser point occupying the current observation angle range. Among them, the robot sets the obstacle marking logic information corresponding to the laser point marked as an obstacle point in each frame of line laser data to logic 1; the robot sets the obstacle marking logic information corresponding to the laser point not marked as an obstacle point in each frame of line laser data to logic 0.

[0048] The robot sequentially controls the obstacle marking logic information corresponding to each laser point in a frame of line laser data collected previously and the obstacle marking logic information corresponding to the laser points occupying the same observation angle range in a frame of line laser data collected currently to perform a logic AND operation, and obtains the obstacle marking logic operation results corresponding to the laser points occupying each observation angle range, and then counts the number of observation angle ranges occupied by the laser points whose obstacle marking logic operation results are logic 1, and then sets the counted number of observation angle ranges as the repeated angle number, so that between two frames of line laser data collected sequentially, the repeatedly occupied observation angle range is counted only once.

[0049] Figure 7 An embodiment of the present application discloses a robot in Figure 5 A frame of line laser data collected in Figure 6 Schematic diagram of the logic processing of a frame of line laser data collected in the image according to the detection angles divided in sequence within the preset detection angle range, where the row of squares where frame1 is located represents the robot Figure 5 The one frame of line laser data collected in the figure is regarded as the observation angle range occupied by the corresponding laser point represented by each square in the first row of the diagram. The squares in the first row represent the situation where each laser point in the one frame of line laser data collected previously is marked as an obstacle point, that is, the squares in the first row are occupied by obstacle points, thereby listing the obstacle marking logic information of each laser point in the one frame of line laser data collected previously, specifically the obstacle marking logic information of the laser points occupying each observation angle range.

[0050] The row of squares where frame2 is located indicates that the robot is Figure 6 The one frame of line laser data collected in the diagram is regarded as the observation angle range occupied by the corresponding laser point represented by each square in the second row of the diagram, and the squares in the second row represent the situation that each laser point in the one frame of line laser data currently collected is marked as an obstacle point, that is, the squares in the second row are occupied by obstacle points; thereby, the obstacle marking logic information of each laser point in the one frame of line laser data currently collected is listed, specifically, the obstacle marking logic information of the laser points occupying each observation angle range.

[0051] exist Figure 7 In each square of frame1, the laser points occupying white squares are not marked as obstacle points, and the laser points occupying black squares are marked as obstacle points. There are 8 black-filled squares in the row of squares where frame1 is located, that is, there are 8 squares occupied by laser points with obstacle marking logic information set to logic 1, and the one-frame line laser data collected previously is a legal data frame. There are 17 black-filled squares in the row of squares where frame2 is located, that is, the number of squares occupied by laser points with obstacle marking logic information set to logic 1 is 17.

[0052] When the second preset observation angle quantity threshold is 8 and the third preset observation angle quantity threshold is 30, whether it is the currently acquired frame of line laser data or the previously acquired frame of line laser data, the number of black-filled squares occupied in each frame of line laser data is greater than or equal to 8, and the number of black-filled squares occupied is less than 30, and the currently acquired frame of line laser data and the previously acquired frame of line laser data both form legal data frames.

[0053] The row of squares where frame1 is located indicates that the robot is Figure 5 A frame of line laser data collected in the diagram is considered to be represented by the first row of squares representing the observation angle range occupied by the corresponding laser point. The squares in the first row that are arranged continuously and filled with black represent Figure 5 The observation angle range occupied by the black bold rectangle (which can be regarded as a black convex dot) generated at the intersection of the middle light bar 104 and the linear obstacle 106 can be represented by at least one square. The longer the black bold rectangle is in the vertical direction of the navigation direction OP, the more black-filled squares are represented and the more they are arranged continuously.

[0054] The row of squares where frame2 is located indicates that the robot is Figure 6 A frame of line laser data collected in the figure is regarded as each square in the second row of the diagram representing the observation angle range occupied by the corresponding laser point, and the squares in the first row of the grid that are arranged continuously and filled with black represent Figure 6 The observation angle range occupied by the black bold rectangle (which can be regarded as a black convex dot) generated at the intersection of the middle light bar 104 and the linear obstacle 106 can be represented by at least one square. The longer the black bold rectangle is in the vertical direction of the navigation direction OP, the more black-filled squares are represented and the more they are arranged continuously.

[0055] Figure 6 The black bold rectangle generated at the intersection of the light bar 104 and the linear obstacle 106 is Figure 5 There are many black bold rectangles generated at the intersection of the light bar 104 and the linear obstacle 106, especially on the right side of the light bar 104, corresponding to Figure 7 In the example, the number of the rightmost consecutive squares filled with black in the second row of squares is at least 13, and the number of the rightmost consecutive squares filled with black in the first row of squares is 2.

[0056] exist Figure 7In the figure, the black-filled squares in the first row and the second row are aligned as the obstacle mark logic information with a logic value of 1 corresponding to the laser points occupying the same observation angle range participating in the logic AND operation in the two frame line laser data; after the obstacle mark logic information corresponding to the squares in the first row and the second row is logically ANDed, the obtained logic AND operation result is represented by the squares in the row where frame1&frame2 are located, and in the squares in the fourth row of the figure, the obstacle mark logic operation result corresponding to the laser points at each observation angle range is obtained, and the black-filled squares in the fourth row of squares cover the observation angle ranges occupied by the laser points marked as obstacle points in the repeated area of ​​the observation angle range in the first frame line laser data (the black-filled squares in the first row) and the second frame line laser data (the black-filled squares in the second row); since the number of black-filled squares in the fourth row of squares is equal to 5, the corresponding number of repeated angles is equal to the value 5, which is equal to the number of observation angle ranges occupied by the laser points whose obstacle mark logic operation result is logic 1. The bitwise "AND" logic operation is used to count the number of obstacle points in the angular overlap area of ​​two adjacent frames of laser data.

[0057] As an embodiment, in step 22, the number of observation angle ranges that are not repeatedly occupied by obstacle points marked in two frames of linear laser data collected sequentially is counted, and the method for obtaining the total number of occupied angles includes: The robot divides the two frames of line laser data collected in sequence into a frame of line laser data collected previously and a frame of line laser data collected currently; for each frame of line laser data, the robot divides the preset detection angle range of the line laser sensor into the number of observation angle ranges for target detection in advance according to the established clock direction, and the angle value of each observation angle range is equal; the preset detection angle range of the line laser sensor forms a fixed angle range on both sides of the robot's body axis; in the same frame of line laser data, each observation angle range remains unchanged while the robot walks along the navigation direction; a laser point with the smallest angle value is selected from multiple laser points falling into the current observation angle range and configured as the laser point occupying the current observation angle range. Among them, the robot sets the obstacle marking logic information corresponding to the laser point marked as an obstacle point in each frame of line laser data to logic 1; the robot sets the obstacle marking logic information corresponding to the laser point not marked as an obstacle point in each frame of line laser data to logic 0.

[0058] The robot sequentially controls the obstacle marking logic information corresponding to each laser point in the first frame of line laser data collected previously and the obstacle marking logic information corresponding to the laser points occupying the same observation angle range in the currently collected frame of line laser data to perform a logical OR operation, and obtains the obstacle marking logic operation results corresponding to the laser points occupying each observation angle range, and then counts the number of observation angle ranges occupied by the laser points whose obstacle marking logic operation results are logic 1, and then sets the counted number of observation angle ranges as the total number of occupied angles, forming the number of observation angle ranges that are not repeatedly occupied by obstacle points in the two frames of line laser data collected sequentially, which is equivalent to the result obtained by subtracting the aforementioned repeated angle number (the number of observation angle ranges that have been repeatedly occupied by laser points whose obstacle marking logic information is set to logic 1) from the total number of observation angle ranges occupied by all laser points in the two frames of line laser data collected sequentially.

[0059] Figure 7 An embodiment of the present application discloses a robot in Figure 5 A frame of line laser data collected in Figure 6 Schematic diagram of the logic processing of a frame of line laser data collected in the image according to the detection angles divided in sequence within the preset detection angle range, where the row of squares where frame1 is located represents the robot Figure 5 The first row of squares in the figure represents the observation angle range occupied by the corresponding laser point. The squares in the first row represent the situation where each laser point in the first frame of line laser data collected is marked as an obstacle point; the squares in the row where frame2 is located represent the situation where the robot is in Figure 6 A frame of line laser data collected in the diagram is regarded as each square in the second row representing the observation angle range occupied by the corresponding laser point, and the squares in the second row represent the obstacle marking logic information corresponding to each laser point in the currently collected frame of line laser data.

[0060] exist Figure 7In each square of frame1, the laser point occupying the white square is not marked as an obstacle point, and the laser point occupying the black-filled square is marked as an obstacle point. There are 8 black-filled squares in the row of squares where frame1 is located, that is, there are 8 squares occupied by laser points whose obstacle marking logic information is set to logic 1, and the previously collected frame of line laser data belongs to a legal data frame. There are 17 black-filled squares in the row of squares where frame2 is located, that is, the number of squares occupied by laser points whose obstacle marking logic information is set to logic 1 in the row of squares where frame2 is located is 17. When the second preset observation angle number threshold is 8 and the third preset observation angle number threshold is 30, whether it is the currently collected frame of line laser data or the previously collected frame of line laser data, the number of black-filled squares occupied in each frame of line laser data is greater than or equal to 8, and the number of black-filled squares occupied is less than 30, and the currently collected frame of line laser data and the previously collected frame of line laser data both form legal data frames.

[0061] Figure 6 The black bold rectangle generated at the intersection of the light bar 104 and the linear obstacle 106 is Figure 5 There are many black bold rectangles generated at the intersection of the light bar 104 and the linear obstacle 106, especially on the right side of the light bar 104, corresponding to Figure 7 In the example, the number of the rightmost consecutive squares filled with black in the second row of squares is at least 13, and the number of the rightmost consecutive squares filled with black in the first row of squares is 2.

[0062] exist Figure 7 In the figure, the black-filled squares in the first and second rows are aligned as the obstacle marking logic information with a logic value of 1 corresponding to the laser points occupying the same observation angle range participating in the logic OR operation in the two frames of line laser data; after the obstacle marking logic information corresponding to the squares in the first and second rows are logically ORed, the obtained logic AND operation result is represented by the squares in the row where frame1|frame2 is located, and in the squares in the third row of the figure, the obstacle marking logic operation result corresponding to the laser points at each observation angle range is obtained, and the black-filled squares in the third row of squares cover the observation angle ranges occupied by all the laser points marked as obstacle points in the first frame of line laser data (black-filled squares in the first row) and the second frame of line laser data (black-filled squares in the second row); since the number of black-filled squares in the third row of squares is equal to 20, the corresponding total number of occupied angles is equal to the value 20. The bitwise "OR" logic operation is used to count the number of observation angle ranges that are not repeatedly occupied by the obstacle points marked in two adjacent frames of laser data.

[0063] It is worth noting that after the line laser sensor detects the wall, the number of obstacle points counted will account for the majority after the logical AND operation required to be performed between the two frames of line laser data corresponding to the obstacle marking logic information. Therefore, this embodiment can be combined with the number of obstacle points in the angular overlapping area of ​​the two adjacent frames of laser data obtained by the bit "AND" logic operation in the aforementioned embodiment to eliminate the influence of walls or other large obstacles (such as rope-like obstacles that are zigzag and laid flat on the ground).

[0064] Based on the above embodiments, Figure 7 In the two frames of line laser data collected sequentially, the total number of occupied angles is greater than or equal to 20, and the number of repeated angles (equal to 5) needs to be less than the ratio (greater than 10) of the total number of occupied angles (equal to 20) to a preset reduction factor (preferably 1.5), then the line obstacle can be identified by executing step 23.

[0065] In some embodiments, the robot marks the position where it is when acquiring the previously acquired frame of line laser data as the first position; the robot marks the position where it is when acquiring the currently acquired frame of line laser data as the second position; schematically, Figure 5 An embodiment of the present application discloses a scene in which a robot walks toward a linear obstacle 106. When the robot walks to a first position along a navigation direction OP, a line laser is projected onto the linear obstacle 106. The linear obstacle 106 is placed horizontally on the walking surface of the robot in a curved and uneven shape. Figure 6 An embodiment of the present application discloses a scene in which a robot walks toward a linear obstacle 106. When the robot walks to a second position along the navigation direction OP, a linear laser is projected onto the linear obstacle 106. The linear obstacle 106 is placed horizontally on the walking surface of the robot in a curved and uneven shape. The second position is relative to Figure 5 The first position of the robot is closer to the linear obstacle 106, which can be understood as the robot walking a distance step from the first position along the navigation direction OP to the second position. During the process of the robot walking from the first position to the second position along the navigation direction, the distance between the robot and the surface of the object to be measured becomes smaller, so that the robot recognizes the surface of the object to be measured as having a linear obstacle at the second position and then starts to change the navigation direction to avoid the linear obstacle.

[0066] In some embodiments, the number of target detections is 60, that is, the number of observation angle ranges that can be divided in a frame of line laser data can reach 60; the first preset observation angle number threshold is 20, and the preset reduction factor is 1.5; the second preset observation angle number threshold is 8, and the third preset observation angle number threshold is 30; the surmountable obstacle height threshold is 20mm, and the reference height is 2mm. Therefore, in order to eliminate the interference of obstacles other than the linear obstacles, the corresponding Figure 7 In the first frame of line laser data frame1 (represented by the squares in the row where frame1 is located) and the second frame of line laser data frame2 (represented by the squares in the row where frame2 is located), the laser point in each frame of line laser data needs to occupy more than or equal to 8 black-filled squares and less than 30 black-filled squares to form a legal data frame, and in two consecutively identified legal data frames, the total number of occupied angles needs to be greater than or equal to 20, and the number of repeated angles needs to be less than the ratio of the total number of occupied angles to 1.5 to identify the linear obstacle, so that the accuracy of identifying the surface of the object to be measured as having linear obstacles is adjusted to a reasonable range according to the relationship between the number of repeated angles and the total number of occupied angles.

[0067] As an embodiment, in step 21, it also includes: judging whether the two frames of line laser data collected in sequence have only laser slopes in the same direction, if so, when the maximum height of the laser point in each frame of line laser data is less than the obstacle height threshold that can be crossed, the robot identifies the surface of the object to be measured as having a step-type obstacle, otherwise it is determined that the robot has detected two laser slopes in different directions in at least one frame of line laser data and executes step 22; wherein, the step-type obstacle has a contour extending along a preset direction with the same height, the preset direction is not parallel to the navigation direction, the preset direction is not perpendicular to the navigation direction, the navigation direction is perpendicular to the extension direction of the light strip formed by the projection of the line laser sensor, and the preset direction is preferably the extension direction of the longest contour of the step-type obstacle. Thus, the robot accurately distinguishes the line obstacle from the step-type obstacle by using the monotonous change characteristics of the connecting line of each laser point in each frame of line laser data.

[0068] Specifically, the method of detecting whether the two frames of line laser data collected in sequence both have only laser slopes in the same direction includes: while the robot keeps walking along the navigation direction, in the two frames of line laser data collected in sequence, judging whether the lines connecting each laser point in each frame of line laser data all show the presence of an ascending laser slope and no descending laser slope, or judging whether the lines connecting each laser point in each frame of line laser data all show the presence of a descending laser slope and no ascending laser slope. Then, when each frame of line laser data shows the presence of an ascending laser slope and no descending laser slope, or each frame of line laser data shows the presence of a descending laser slope and no ascending laser slope, the robot identifies the surface of the object to be measured as having the step-type obstacle, and determines that the placement direction of the step-type obstacle is at a certain inclination angle with the navigation direction.

[0069] It should be noted that the laser slopes in the same direction are rising laser slopes or falling laser slopes. Figure 3 When the light strip 104 is projected onto the step-like obstacle 105, a laser slope 1041 appears, and a line connecting the laser points belonging to the line segment 1041 is formed. Figure 4 When the light strip 104 is projected onto the step-like obstacle 105, a laser slope 1042 appears, and a line connecting the laser points belonging to the line segment 1042 is formed. Figure 3 The laser ramp 1041 and Figure 4 The laser slope 1042 in the figure is a laser slope in the same direction. The clockwise direction is defined as an ascending laser slope, and the counterclockwise direction is defined as a descending laser slope. The connecting line of each laser point in the laser slope in the same direction shows a monotonically changing characteristic. The laser slope 1041 and the laser slope 1042 are both detected by the robot within a continuous period of time, and the position of the robot changes so that the laser slope 1041 and the laser slope 1042 both span multiple angles.

[0070] For identifying obstacles like hills, the inclination direction of the laser slope is stable. When the robot approaches an obstacle, because the robot's walking direction does not change, if the laser slope shows an upward trend, the laser slope detected by the robot in the process of walking along the navigation direction will remain upward; if the laser slope shows a downward trend, the laser slope detected by the robot in the process of walking along the navigation direction will remain downward; anyway, there will not be both an upward and downward trend in the same frame of line laser data. Therefore, the height feature of the laser point of the hill-like obstacle on the ground is a straight line, to distinguish it from a line obstacle.

[0071] When it is determined that the two frames of line laser data collected sequentially have and only have laser slopes in the same direction, that is, the laser slope can be connected in each frame of line laser data and the direction of the slope is the same (either rising or falling, and rising and falling are not allowed to exist at the same time), the robot identifies the surface of the object to be measured as having a step-like obstacle, and determines that the placement direction of the step-like obstacle is at a certain inclination angle with the navigation direction, and can determine that the maximum height of the laser point in each frame of line laser data is less than the height threshold of the surmountable obstacle, and the height threshold of the surmountable obstacle is preferably 20 mm.

[0072] The two frames of line laser data collected sequentially can be understood as two frames of line laser data collected continuously, or two consecutive frames of line laser data, or two adjacent frames of line laser data. There is a collection time sequence between different frames of line laser data, and it is also related to the position of the robot, that is, the robot collects two frames of line laser data at different positions at different times through the line laser sensor.

[0073] In this embodiment, the navigation direction is perpendicular to the extension direction of the light bar formed by the line laser sensor, so that the light bar is not parallel to the placement direction of the step-like obstacle, and the placement direction of the step-like obstacle is the extension direction of the longest contour of the step-like obstacle. Preferably, the step-like obstacle has a contour extending along a preset direction with the same height, the preset direction is not parallel to the navigation direction, and the preset direction is not perpendicular to the navigation direction.

[0074] Obstacles such as Figure 3 As shown, Figure 3 An embodiment of the present application discloses a schematic diagram of a line laser projected onto a step-like obstacle 105 when the robot walks to a first position along a navigation direction OP in a scenario where the robot walks toward a step-like obstacle 105; wherein, when the light bar 104 passes through the step-like obstacle 105, a laser slope 1041 appears (defined as an ascending laser slope in a clockwise direction (monotonically increasing at the height of the laser point), and defined as a descending laser slope in a counterclockwise direction (monotonically decreasing at the height of the laser point)), the placement direction of the step-like obstacle 105 forms a certain angle with the navigation direction OP but is not perpendicular to each other, and the placement direction of the step-like obstacle 105 is regarded as the extension direction of the longest contour of the step-like obstacle 105.

[0075] In some embodiments of identifying the step-like obstacles, if the robot collects one frame of line laser data each time it walks a distance step along the navigation direction, and after collecting two frames of line laser data in sequence, if the lines connecting the laser points in each frame of line laser data collected corresponding to the height less than or equal to the obstacle height threshold all have rising laser slopes and no falling laser slopes, then the robot identifies the surface of the object to be measured in front of it as a step-like obstacle, and determines that the placement direction of the step-like obstacle is at a certain inclination angle with the navigation direction, that is, the walking direction of the robot is diagonally opposite to the step-like obstacle, wherein the placement direction of the step-like obstacle is the extension direction of the longest contour of the step-like obstacle.

[0076] The reference height is less than the surmountable obstacle height threshold, and the surmountable obstacle height threshold is less than the installation height of the line laser sensor in the robot (preferably 45 mm). Each laser point whose height is less than or equal to the surmountable obstacle height threshold (preferably 20 mm) is marked as an obstacle point when its height is greater than the reference height (preferably 2 mm), and is connected to form a surmountable obstacle outline. This surmountable obstacle outline meets the requirements for setting the outline of the step-type obstacle.

[0077] The step-like obstacles extend at the same height along the extension direction of their longest contours to form a crossable and regular obstacle. The extension direction of the longest contour of the step-like obstacles is neither parallel to the navigation direction nor perpendicular to the navigation direction. The robot faces the step-like obstacles diagonally during walking. The extension direction of the longest contour of the step-like obstacles is tilted relative to the robot's body center axis. If the step-like obstacles can be identified based on the laser slope in the same direction, the relationship between the number of repeated angles and the total number of occupied angles will not be detected.

[0078] Indicatively, Figure 3 This is a schematic diagram of a robot walking toward a step-like obstacle 105 in an embodiment of the present application. When the robot walks to the first position along the navigation direction OP, a line laser is projected onto the step-like obstacle 105; wherein, when the light bar 104 passes the step-like obstacle 105, a laser slope 1041 appears (defined as an ascending laser slope in the clockwise direction and a descending laser slope in the counterclockwise direction), and the extension direction of the step-like obstacle 105 forms a certain angle with the navigation direction OP but is not perpendicular to each other. The left and right sides of the laser slope 1041 are both regarded as straight laser lines perpendicular to the navigation direction OP, and the height of the laser point on each side remains unchanged, and is not configured as a laser slope.

[0079] Figure 4An embodiment of the present application discloses a schematic diagram of a scene in which a robot walks toward a step-like obstacle 105, and when the robot walks to a second position along a navigation direction OP, a line laser is projected onto the step-like obstacle 105. The second position is relative to Figure 3 The first position is closer to the step-like obstacle 105, which can be understood as the robot walking a distance step from the first position along the navigation direction OP to the second position; wherein, when the light bar 104 passes the step-like obstacle 105, a laser slope 1042 appears (defined as an ascending laser slope in a clockwise direction and a descending laser slope in a counterclockwise direction), and the extension direction of the step-like obstacle 105 is at a certain angle to the navigation direction OP but not perpendicular to each other. The extension direction of the longest contour of the step-like obstacle 105 is at a certain angle to the navigation direction OP but not perpendicular to each other. The left and right sides of the laser slope 1042 are both regarded as straight laser lines perpendicular to the navigation direction OP, and the height of the laser point on each side remains unchanged and is not configured as a laser slope. The length of the straight laser line distributed on the left side of the laser slope 1042 is greater than Figure 3 The length of the straight laser line distributed on the left side of the laser slope 1041 is short, and the number of corresponding distributed laser points is reduced. The length of the straight laser line distributed on the right side of the laser slope 1042 is shorter than Figure 3 The length of the straight laser line distributed on the right side of the laser slope 1041 is long, and the number of corresponding distributed laser points increases, indicating that the light bar 104 is moving obliquely toward the left end of the hill-like obstacle 105 .

[0080] As an embodiment, when the robot keeps walking along the navigation direction and determines that the lines connecting the laser points in at least one frame of line laser data show both an ascending laser slope and a descending laser slope, and the two frames of line laser data collected successively do not both have and only have laser slopes in the same direction, it is determined that the robot has detected two laser slopes in different directions in at least one frame of line laser data, and then starts to execute step 22 to eliminate the interference of the step-type obstacles on the identification of line obstacles.

[0081] For a scene where the line connecting each laser point in a frame of line laser data presents both an ascending laser slope and a descending laser slope and the necessity for identifying the linear obstacle, the disclosure Figure 5In the scenario where the robot walks toward the linear obstacle 106, in this scenario, when the robot walks to a position along the navigation direction OP, the line laser is projected onto the linear obstacle 106. The linear obstacle 106 is placed horizontally on the robot's walking surface in a tortuous and uneven form. Then the robot can identify the linear obstacle 106 on the surface of the object to be measured. Specifically, the light bar 104 is projected onto the surface of the linear obstacle 106, and it can be regarded that the outline of the linear obstacle 106 passes through the light bar 104 in a curved manner and a light spot offset occurs at the intersection, such as Figure 5 As shown in the black bold rectangle, multiple convex points with different directions are generated on the straight line where the light bar 104 is located; the intersection of the light bar 104 and the linear obstacle 106 can be regarded as the position where the linear obstacle 106 is detected by the linear laser. The light bar 104 changes at the intersection and reflects back to the linear laser sensor to form laser points reflected from the surface of the linear obstacle, and the connection shape reflects the undulating change characteristics of the outline of the linear obstacle.

[0082] Moreover, combined with Figure 5 It can be seen that in the same extension direction, there are rising and falling directions of the light spot. Figure 5 On the line segment 104, the second intersection from left to right (black bold rectangle) has a rising trend of the light spot, and the fourth intersection from left to right (black bold rectangle) has a falling trend of the light spot. It can be understood that the light strip 104 has laser slopes with different directions, for example, there is at least one rising laser slope and at least one falling laser slope at the same time.

[0083] Indicatively, in Figure 5 In the scenario shown, when the robot walks to the first position along the navigation direction OP, the line laser is projected onto the linear obstacle 106, which is placed horizontally on the robot's walking surface in a curved and uneven shape. Figure 6 In the scenario shown, when the robot walks along the navigation direction OP to the second position, the line laser is projected onto the linear obstacle 106, and the linear obstacle 106 is placed horizontally on the walking surface of the robot in a curved and uneven shape. Figure 5 The first position of the robot is closer to the linear obstacle 106, which can be understood as the robot walking a distance step from the first position along the navigation direction OP to the second position; Figure 6 The black bold rectangle generated at the intersection of the light bar 104 and the linear obstacle 106 is Figure 5 There are many black bold rectangles at the intersection of the light bar 104 and the linear obstacle 106, especially on the right side of the light bar 104. Figure 5 and Figure 6On the straight line where the light bar 104 is located, convex points with an ascending trend and convex points with a descending trend are generated. The convex points with an ascending trend indicate the direction in which the light spot deviates upward after being projected on the linear obstacle 106, and the convex points with a descending trend indicate the direction in which the light spot deviates downward after being projected on the linear obstacle 106; thus, the morphological distribution characteristics of the linear obstacle 106 are reflected. The linear obstacle 106 passes from one side of the line segment 104 to the other side. The linear obstacle 106 is laid on the surface of the object to be measured in a curved shape as a whole. The surface of the object to be measured can be regarded as the ground or the walking surface of the robot.

[0084] In some embodiments, the linear obstacles identified are mainly lines across the floor, which need to be judged by combining the previous and next frames of line laser data. Specifically, the linear obstacles are continuous, curved and flat. For example, when the robot walks along the navigation direction at a certain distance step, it collects the first frame of line laser data when it moves to the first position, and extracts part of the rope. After moving a distance step, it reaches the second position and collects the second frame of line laser data, and extracts other parts of the rope. The two parts extracted successively by the robot may have overlapping areas, and the corresponding first judgment is that the lines connecting the laser points in at least one frame of line laser data show rising laser slopes and falling laser slopes. , and then combined with the size relationship between the number of repeated angles and the total number of occupied angles to identify the linear obstacle. The main characteristics of the linear obstacle are that it is short (generally not higher than 20 mm), continuous, and curved to the horizontal ground. If the height feature of the laser point is directly used for identification, since the height is small and the light bar formed by the linear laser emission is a straight line, it is not enough to form an obvious recognition effect at one time. Therefore, this embodiment only uses two frames of line laser data collected in sequence to detect the linear obstacle based on the consideration of the calculation amount and the walking distance of the robot, which saves the calculation amount and prevents the robot from being entangled and stuck by the obstacle before the type of obstacle is identified due to the excessive walking distance.

[0085] Although the regularity of the contour surface of the rope zigzagging and laying on the ground is different from that of the low step, the contour height distribution characteristics of the rope zigzagging and laying on the ground collected by the robot at a specific angle are similar to the contour height distribution characteristics reflected from the low step surface collected by the robot walking along a specific oblique direction relative to the low step. However, at least it can be determined that the obstacles on the surface of the object to be measured are low obstacles, excluding the influence of high obstacles such as wall obstacles, and then the linear obstacles and the step obstacles can be distinguished within the scope of low obstacles. Therefore, this embodiment first determines whether there are step obstacles on the surface of the object to be measured by judging whether the two frames of line laser data collected in sequence have and only have laser slopes in the same direction; and then determines whether there are linear obstacles on the surface of the object to be measured based on the size relationship between the number of repeated angles and the total number of occupied angles. Reduce the probability of misidentification.

[0086] On the basis of step 21 disclosed in the above embodiment, the method for determining the rising laser slope or the falling laser slope includes: During the process of the robot collecting the one frame of line laser data, the robot records the heights of the laser points occupying the corresponding observation angle ranges in turn according to the divided observation angle ranges, and detects the height changes of the laser points occupying the corresponding observation angle ranges in turn according to the predetermined clock direction, mainly to capture the height change characteristics of the laser points in the section where the laser slope exists.

[0087] In the frame of line laser data collected by the robot, it is detected whether there is an increase in height of laser points occupying at least three observation angle ranges that are continuously distributed. If so, it is determined that there is a rising laser slope in the frame of line laser data; otherwise, it is determined that there is no rising laser slope in the frame of line laser data; specifically, if an increase in height of laser points occupying at least three observation angle ranges that are continuously distributed is detected along the predetermined time needle direction, it is determined that there is an ascending laser slope on the line connecting each laser point in the frame of line laser data collected by the robot, which can be understood as the laser points or obstacle points occupying at least three observation angle ranges that are continuously distributed in the frame of line laser data are connected in sequence to form an ascending laser slope; if no increase in height of laser points occupying at least three observation angle ranges that are continuously distributed is detected along the predetermined time needle direction, it is determined that there is no ascending laser slope on the line connecting each laser point in the frame of line laser data collected by the robot.

[0088] It should be noted that the rising laser slope is represented by connecting the laser points rising along the predetermined clock direction in sequence. In this embodiment, the heights of the laser points occupying at least three observation angle ranges of continuous distribution increase gradually, corresponding to Figure 7In the example, there are at least three consecutive squares. In the predetermined clock direction, except for the first square, the height of the laser point corresponding to each square (or the laser point occupying the square) is greater than the height of the laser point corresponding to the previous square. Then, the adjacent laser points occupying the corresponding squares are connected in sequence to form an ascending laser slope, and the slope rises along the predetermined clock direction. If the predetermined clock direction is clockwise, a laser slope can be formed. Figure 5 Middle slope 1041 or Figure 6 The slope in 1042.

[0089] In the frame of line laser data collected by the robot, it is detected whether there is a decrease in height of laser points occupying at least three observation angle ranges that are continuously distributed. If so, it is determined that there is a descending laser slope in the frame of line laser data; otherwise, it is determined that there is no descending laser slope in the frame of line laser data. Specifically, if a decrease in height of laser points occupying at least three observation angle ranges that are continuously distributed is detected along the predetermined clock direction, it is determined that there is a descending laser slope on the line connecting each laser point in the frame of line laser data collected by the robot, which can be understood as the laser points or obstacle points occupying at least three observation angle ranges that are continuously distributed in the frame of line laser data are connected in sequence to form a descending laser slope. If no decrease in height of laser points occupying at least three observation angle ranges that are continuously distributed is detected along the predetermined clock direction, it is determined that there is no descending laser slope on the line connecting each laser point in the frame of line laser data collected by the robot.

[0090] It should be noted that the descending laser slope is represented by connecting the laser points descending along the predetermined clock direction in sequence. In this embodiment, the heights of the laser points occupying at least three observation angle ranges of continuous distribution decrease, corresponding to Figure 7 In the given clockwise direction, there are at least three consecutive squares. In the given clockwise direction, except for the first square, the height of the laser point corresponding to each square (or the laser point occupying the square) is smaller than the height of the laser point corresponding to the previous square. Then, the adjacent laser points occupying the corresponding squares are connected in sequence to form a descending laser slope, and the slope descends along the given clockwise direction. If the given clockwise direction is counterclockwise, a descending laser slope can be formed. Figure 5 Middle slope 1041 or Figure 6 The slope in 1042.

[0091] To summarize, in the two frames of line laser data collected sequentially, for each frame of line laser data, the robot detects that there is an increase in the height of the laser points occupying at least three observation angle ranges of continuous distribution, and detects that there is no decrease in the height of the laser points occupying at least three observation angle ranges of continuous distribution, then it is determined that the lines connecting the laser points in this frame of line laser data all show that there is an ascending laser slope and no descending laser slope. At this time, the robot identifies the surface of the object to be measured as having the step-type obstacle, and determines that the placement direction of the step-type obstacle is at a certain inclination angle with the navigation direction.

[0092] In the two frames of line laser data collected sequentially, for each frame of line laser data, the robot detects that there is no increase in the height of the laser points occupying at least three observation angle ranges of continuous distribution, and detects that there is a decrease in the height of the laser points occupying at least three observation angle ranges of continuous distribution, then it is determined that the lines connecting the laser points in this frame of line laser data all show that there is a descending laser slope and there is no ascending laser slope. At this time, the robot recognizes the surface of the object to be measured as having the step-type obstacle, and determines that the placement direction of the step-type obstacle is at a certain inclination angle with the navigation direction.

[0093] The above is a detailed introduction to an embodiment of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A linear obstacle recognition method based on line laser, wherein a line laser sensor is installed on the front side of the robot body; the method is characterized in that: The linear obstacle recognition method comprises: Step 1: When the robot is walking along the navigation direction, the line laser sensor is controlled to emit a line laser, and two frames of line laser data formed by the line laser being reflected by the surface of the object to be measured are collected in sequence; Step 2: Based on the laser slope in each frame of line laser data collected in step 1 and the relationship between the number of repeated angles and the total number of occupied angles, the robot identifies the surface of the object to be measured as having a linear obstacle; The number of repeated angles and the total number of occupied angles are obtained by counting the repeated occupied angles of obstacle points in the two frames of line laser data collected sequentially in step 1.

2. The linear obstacle recognition method according to claim 1, characterized in that: In step 2, the method for the robot to identify the surface of the object to be measured as having a linear obstacle by combining the laser slope in each frame of line laser data collected in step 1 and the size relationship between the number of repeated angles and the total number of occupied angles includes: Step 21, when the robot detects that there are two laser slopes with different directions in at least one frame of line laser data, execute step 22; Step 22, counting the number of observation angle ranges repeatedly occupied by the obstacle points marked in the two frames of line laser data collected sequentially, to obtain the number of repeated angles; and counting the number of observation angle ranges not repeatedly occupied by the obstacle points marked in the two frames of line laser data collected sequentially, to obtain the total number of occupied angles; then determining that the number of repeated angles and the total number of occupied angles are both obtained by counting the situation of repeated occupied angles by the obstacle points in the two frames of line laser data collected sequentially in step 1; then executing step 23; Step 23: According to the relationship between the number of repeated angles and the total number of occupied angles, the robot identifies the surface of the object to be measured as having a linear obstacle; Among them, the robot marks the laser points in each frame of line laser data whose height is greater than the reference height as obstacle points, and the robot does not mark the laser points in each frame of line laser data whose height is less than or equal to the reference height as obstacle points.

3. The linear obstacle recognition method according to claim 2, characterized in that: In step 23, according to the magnitude relationship between the number of repeated angles and the total number of occupied angles, the method for the robot to identify the surface of the object to be detected as having linear obstacles includes: When the total number of occupied angles is greater than or equal to the first preset observation angle number threshold, and the number of repeated angles is less than the ratio of the total number of occupied angles to the preset reduction coefficient, the robot identifies the surface of the object to be measured as having linear obstacles, and determines that the heights of each laser point in the two frames of line laser data collected sequentially are less than or equal to the traversable obstacle height threshold, wherein the reference height is less than the traversable obstacle height threshold, and the traversable obstacle height threshold is less than the installation height of the line laser sensor in the robot.

4. The linear obstacle recognition method according to claim 3, characterized in that: In a frame of line laser data collected in step 1, if it is detected that the number of observation angle ranges occupied by the laser points is greater than or equal to the second preset observation angle number threshold, and the number of observation angle ranges occupied by the laser points is less than or equal to the third preset observation angle number threshold, then the frame of line laser data collected in step 1 is marked as a legal data frame; If two frames of legal data frames are collected in sequence, the two frames of legal data frames are marked as two frames of line laser data collected in sequence to obtain the number of repeated angles and the total number of occupied angles; Among them, the second preset observation angle quantity threshold is smaller than the first preset observation angle quantity threshold, and the first preset observation angle quantity threshold is smaller than the third preset observation angle quantity threshold.

5. The linear obstacle recognition method according to claim 4, characterized in that: The robot divides the preset detection angle range of the line laser sensor into the number of the target detection observation angle ranges according to the predetermined clock direction, so that each observation angle range remains unchanged during the robot's walking along the navigation direction; wherein the line laser emitted by the line laser sensor forms the preset detection angle range; Before counting the number of repeated angles and the total number of occupied angles in step 22, a laser point with the smallest angle value is selected from multiple laser points falling within a current observation angle range and configured as a laser point occupying a current observation angle range, so that obstacle points marked in the same frame line laser data are configured to not repeatedly occupy the same observation angle range.

6. The linear obstacle recognition method according to claim 5, characterized in that: In step 22, the number of observation angle ranges repeatedly occupied by obstacle points marked in two frames of linear laser data collected sequentially is counted, and the method for obtaining the number of repeated angles includes: The robot divides the two frames of line laser data collected sequentially into a frame of line laser data collected previously and a frame of line laser data collected currently; The robot sequentially controls the obstacle marking logic information corresponding to each laser point in the previously collected frame of line laser data and the obstacle marking logic information corresponding to the laser points occupying the same observation angle range in the currently collected frame of line laser data to perform a logic AND operation, obtains the obstacle marking logic operation results corresponding to the laser points occupying each observation angle range, then counts the number of observation angle ranges occupied by the laser points whose obstacle marking logic operation results are logic 1, and then sets the counted number of observation angle ranges as the number of repeated angles, so that between two frames of line laser data collected sequentially, the observation angle range that is repeatedly occupied is counted only once; Among them, the robot sets the obstacle marking logic information corresponding to the laser points marked as obstacle points in each frame of line laser data to logic 1; the robot sets the obstacle marking logic information corresponding to the laser points not marked as obstacle points in each frame of line laser data to logic 0.

7. The linear obstacle recognition method according to claim 5, characterized in that: In step 22, the number of observation angle ranges that are not repeatedly occupied by obstacle points marked in two frames of linear laser data collected sequentially is counted, and the method for obtaining the total number of occupied angles includes: The robot divides the two frames of line laser data collected sequentially into a frame of line laser data collected previously and a frame of line laser data collected currently; The robot sequentially controls the obstacle marking logic information corresponding to each laser point in the previously collected frame of line laser data and the obstacle marking logic information corresponding to the laser points occupying the same observation angle range in the currently collected frame of line laser data to perform a logical OR operation, and obtains the obstacle marking logic operation results corresponding to the laser points occupying each observation angle range, and then counts the number of observation angle ranges occupied by the laser points whose obstacle marking logic operation results are logic 1, and then sets the counted number of observation angle ranges as the total number of occupied angles, thereby forming the number of observation angle ranges that are not repeatedly occupied by obstacle points in the two frames of line laser data collected sequentially; Among them, the robot sets the obstacle marking logic information corresponding to the laser points marked as obstacle points in each frame of line laser data to logic 1; the robot sets the obstacle marking logic information corresponding to the laser points not marked as obstacle points in each frame of line laser data to logic 0.

8. The linear obstacle recognition method according to claim 6 or 7, characterized in that: The robot marks the position where it is located when acquiring the frame of line laser data collected previously as a first position; The robot marks the position where it is located when acquiring the currently collected frame of line laser data as a second position; When the robot walks from the first position to the second position along the navigation direction, the distance between the robot and the surface of the object to be measured becomes smaller, so that the robot recognizes the surface of the object to be measured as having linear obstacles at the second position and then starts to change the navigation direction to avoid the linear obstacles.

9. The linear obstacle recognition method according to claim 4, characterized in that: The target detection quantity is 60, the first preset observation angle quantity threshold is 20, and the preset reduction coefficient is 1.5; The second preset observation angle quantity threshold is 8, and the third preset observation angle quantity threshold is 30; The surmountable obstacle height threshold is 20 mm, and the reference height is 2 mm.

10. The linear obstacle recognition method according to claim 3, characterized in that: In the step 21, it also includes: detecting whether the two frames of line laser data collected in sequence have and only have laser slopes in the same direction, if so, when the maximum height of the laser point in each frame of line laser data is less than the obstacle height threshold that can be crossed, the robot identifies the surface of the object to be measured as having a step-like obstacle, otherwise, it is determined that the robot detects two laser slopes with different directions in at least one frame of line laser data and executes the step 22; The step-like obstacle has a contour extending along a preset direction at the same height, the preset direction is not parallel to the navigation direction, and the preset direction is not perpendicular to the navigation direction; The navigation direction is perpendicular to the extension direction of the light strip formed by the projection of the line laser sensor.

11. The linear obstacle recognition method according to claim 10, characterized in that: The method of detecting whether two frames of line laser data collected sequentially have only laser slopes in the same direction includes: While the robot keeps walking along the navigation direction, in the two frames of line laser data collected sequentially, it is determined whether the lines connecting the laser points in each frame of line laser data all show the presence of an ascending laser slope and the absence of a descending laser slope, or it is determined whether the lines connecting the laser points in each frame of line laser data all show the presence of a descending laser slope and the absence of an ascending laser slope; The laser ramps in the same direction are rising laser ramps or falling laser ramps.

12. The linear obstacle recognition method according to claim 11, characterized in that: While the robot keeps walking along the navigation direction, in the two frames of line laser data collected sequentially, it is determined that the line connecting the laser points in at least one frame of line laser data shows that there are both an ascending laser slope and a descending laser slope. Then it is determined that the robot has detected two laser slopes with different directions in at least one frame of line laser data, and then the step 22 is started.

13. The linear obstacle recognition method according to claim 12, characterized in that: In the process of the robot collecting the one frame of line laser data, the height of the laser point occupying the corresponding observation angle range is recorded in sequence according to each divided observation angle range, and the height change of the laser point occupying the corresponding observation angle range is detected in sequence according to the predetermined clock direction; In the frame of line laser data collected by the robot, it is detected whether there is a laser point with a height increase occupying at least three observation angle ranges of continuous distribution, and if so, it is determined that there is a rising laser slope in the frame of line laser data, otherwise, it is determined that there is no rising laser slope in the frame of line laser data; the rising laser slope is represented by connecting the laser points that rise along the predetermined clock direction in sequence; In the frame of line laser data collected by the robot, it is detected whether there is a decreasing height of laser points occupying at least three observation angle ranges of continuous distribution. If so, it is determined that there is a descending laser slope in the frame of line laser data; otherwise, it is determined that there is no descending laser slope in the frame of line laser data; the descending laser slope is represented by connecting the laser points descending along the predetermined clock direction in sequence.

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