Obstacle avoidance method for mobile robot

Abstract

The present invention provides an obstacle avoidance method for a mobile robot, which specifically includes the following steps: (1) planning an original path; (2) determining a temporary safe stopping point Q, wherein the method is to obtain the virtual center point O and radius r of the obstacle, and then determine the safe stopping point based on the maximum radius r1 of the mobile robot and the safety distance j; (3) after the mobile robot reaches point Q, scan whether the obstacle has disappeared. If so, the mobile robot moves along the original path; if not, an obstacle avoidance path is planned. Through the invention of the present invention, a suitable temporary safe stopping point can be determined, which not only facilitates more accurate detection of the obstacle status, but also prevents the mobile robot from colliding with the obstacle.

Description

Technical Field

[0001] The present invention relates to the technical field of obstacle avoidance, and in particular to an obstacle avoidance method for a mobile robot. Background Art

[0002] AGVs, as unmanned, intelligent handling equipment, play a vital role in manufacturing, warehousing, and logistics. Single-steering-wheel AGVs, with their simple chassis structure, straightforward drive system, and low cost, are widely used in industrial logistics.

[0003] Among them, the path planning problem has always been one of the core issues in the intelligent research process of AGV mobile robots. The path planning problem requires the AGV mobile robot to find an optimal or near-optimal path that can avoid obstacles in the working environment. It can be divided into global static path planning and local dynamic path planning.

[0004] For example, a patent document with Chinese patent application number 202410011939.1 and publication date of March 19, 2024, discloses an AGV positioning and path planning method and device. The method includes: controlling the target AGV vehicle to travel from a first target position to a second target position, and obtaining the target AGV vehicle's laser radar data, direction angle data, acceleration and angular velocity data; based on the laser radar data, direction angle data, acceleration and angular velocity data, the target AGV vehicle is positioned and identified and path planned to obtain a first target driving path corresponding to driving from the first target position to the second target position; when the target AGV vehicle travels to the second target position, the first target driving path is encoded and converted to obtain a code-converted driving path, and the code-converted driving path is optimized to obtain a second target driving path corresponding to driving from the second target position to the first target position. This application improves the accuracy of AGV positioning and path planning.

[0005] However, the existing technology of the above method avoids static obstacles, but cannot avoid dynamic obstacles. Some existing technologies can avoid dynamic obstacles, but in the existing dynamic obstacle avoidance process, a suitable temporary stop point is not selected, which makes it inconvenient to accurately detect dynamic obstacles within the specified time. Summary of the Invention

[0006] The present invention provides an obstacle avoidance method for a mobile robot. Through the invention, a suitable temporary safe stopping point can be determined, which on the one hand facilitates more accurate detection of the state of the obstacle, and on the other hand can avoid collision between the mobile robot and the obstacle.

[0007] To achieve the above object, the technical solution of the present invention is: a method for avoiding obstacles of a mobile robot, characterized in that the specific steps include:

[0008] S1 uses the mobile robot's lidar to obtain surrounding environment information and form a grid map, and uses the A* algorithm to plan the original path of the mobile robot.

[0009] S2 The mobile robot continuously detects whether there are any obstacles on the original path while walking along the original path. If an obstacle is detected, a temporary safe stopping point Q is determined between the mobile robot and the obstacle. The method for determining the temporary safe stopping point Q is:

[0010] S21 calculates the coordinates of the virtual center point O of the obstacle based on the obstacle coordinate information scanned by the laser radar (x k ,y k ); obstacle virtual center point (x k ,y k ) is the average value of the obstacle coordinates obtained by scanning.

[0011] S22 sets the front edge of the mobile robot perpendicular to the original path at the current mobile robot position as edge e, and determines a center line s that passes through the virtual center point O of the obstacle and is parallel to edge e. In the present invention, if the mobile robot is non-rectangular, the maximum outline of the mobile robot forms a rectangle, and the portion of the rectangle closest to the front edge is edge e. In this case, edge e is perpendicular to the original path.

[0012] S23 uses the laser radar to scan the obstacle edge f on the side of the mobile robot with the center line s as the boundary, and obtains the coordinate point (x z ,y z ).

[0013] S24 According to (x k ,y k ) and (x z ,y z ) Calculate the radius r of the virtual obstacle circle with the virtual center point of the obstacle as the center. The calculation method of the radius r of the virtual obstacle circle is:

[0014] .

[0015] S25 Determine the temporary safe stopping point Q at a distance L from the virtual center point O of the obstacle on the original path, where L = r + r1 + j, where r1 is the maximum radius of the mobile robot, and j is the safe distance between the virtual circle of the obstacle formed by r and the virtual circle of the mobile robot formed by r1. This safe distance is determined by presetting it in the mobile robot. The method for determining r1 is: set the length of the mobile robot to L, set the width of the mobile robot to W, then

[0016] S3: The mobile robot remains at a temporary safety stop Q for a time T and continues to detect obstacles using a lidar. If an obstacle is detected within this time, an obstacle avoidance path is planned. This path allows the mobile robot to avoid the obstacle and then continue along the original path. If the obstacle disappears within this time, the mobile robot continues along the original path. The dwell time T is pre-set in the mobile robot. In the present invention, the avoidance path planning is implemented using existing technologies.

[0017] The above method determines the radius r by approaching one side of the mobile robot, and uses the radius r1 formed by the mobile robot, plus a safety distance j, to allow the mobile robot to get as close to the rear end of the obstacle as possible while avoiding collision between the mobile robot and the obstacle. Within time T, the laser radar can better determine whether the obstacle has moved away, thereby improving the accuracy of the judgment.

[0018] Furthermore, in S21,

[0019] ,

[0020] (x i ,y i ) is the obstacle coordinate information, i is the i-th position on the obstacle, and m is the total number of points in the horizontal and vertical directions of obstacle detection. This can improve the accuracy of determining the virtual center point O of the obstacle.

[0021] Furthermore, in S23, the coordinate point (x k ,y k ) is mapped to the map used by the A* algorithm to plan the original path of the mobile robot, with coordinate points (x k ,y k ) is the center of the circle and passes through the edge f of the obstacle scanned by the laser radar. The edge of the obstacle scanned by the laser radar is the distance from the coordinate point (x k ,y k ) is determined as the point with the largest coordinate (x z ,y z ).

[0022] Furthermore, in S24, the radius r of the virtual obstacle circle is calculated as follows:

[0023] .

[0024] Furthermore, if the length of the mobile robot is set to L and the width of the mobile robot is set to W, then In this way, the maximum size of the mobile robot can be determined.

[0025] Furthermore, j is pre-set in the mobile robot.

[0026] Furthermore, the dwell time T is pre-set in the mobile robot. By setting the dwell time T, once the temporary safe stop point Q is determined, the dwell time can be quickly determined by the mobile robot. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the original path planned by the present invention.

[0028] Figure 2 Schematic diagram of obstacle detection for a mobile robot.

[0029] Figure 3 A schematic diagram for identifying temporary safe stopping points. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] A method for avoiding obstacles of a mobile robot, comprising the following steps:

[0032] S1 Figure 1 As shown, the mobile robot 10 uses a laser radar to obtain information about the surrounding environment and form a grid map 20. The A* algorithm is used to plan the original path 1 of the mobile robot 10 from the starting point N1 to the end point N2. This method is an existing technology for determining the original path of the mobile robot and will not be repeated here.

[0033] S2 Figure 2 As shown, when the mobile robot 10 walks along the original path, it continuously scans the original path 1 through the laser radar to detect whether there is an obstacle 2. If the obstacle 2 is detected, a temporary safe stopping point Q is determined between the mobile robot 10 and the obstacle 2. The method for determining the temporary safe stopping point Q is:

[0034] S21 Figure 3 As shown, the coordinates of the virtual center point O of the obstacle are calculated based on the obstacle coordinate information scanned by the laser radar (x k ,y k); obstacle virtual center point (x k ,y k ) is the average value of the obstacle coordinates obtained by scanning. This is achieved through the following formula:

[0035]

[0036] (x i ,y i ) is the obstacle coordinate information, i is the i-th position point on the obstacle, and m is the total number of points in the horizontal and vertical directions of obstacle detection.

[0037] S22: Set the front edge of the mobile robot 10 perpendicular to the original path of the current mobile robot position as edge e, and determine a center line s passing through the virtual center point O of the obstacle and parallel to edge e.

[0038] S23 uses the laser radar to scan the obstacle edge f on the side of the mobile robot with the center line s as the boundary, and obtains the coordinate point (x z ,y z ).

[0039] S24 According to (x k ,y k ) and (x z ,y z ) Calculate the radius r of the virtual obstacle circle with the virtual center point of the obstacle as the center. The calculation method of the radius r of the virtual obstacle circle is:

[0040] .

[0041] S25 Determine the temporary safe stopping point Q at a distance L from the virtual center point O of the obstacle on the original path, where L=r+r1+j, where r1 is the maximum radius of the mobile robot and j is the safe distance between the virtual circle of the obstacle formed by r and the virtual circle of the mobile robot formed by r1. The method for determining r1 is to set the length of the mobile robot to L and the width of the mobile robot to W, then In this embodiment, the position of the mobile robot is located with the center point of the mobile robot as the center of the circle, that is, the center point of the mobile robot corresponds to the original path. When calculating r1, the center point of the mobile robot is also used as the center of the circle. j is stored in the mobile robot in a preset manner.

[0042] S3: The mobile robot remains at the temporary safety stop Q for time T and continues to detect obstacles using the lidar. If obstacles are detected within time T, an obstacle avoidance path is planned. The obstacle avoidance path allows the mobile robot to avoid the obstacle and then continue along the original path. If the obstacle disappears within time T, the mobile robot continues along the original path. In this embodiment, time T is stored in the mobile robot in a preset manner, and the obstacle avoidance path is planned according to existing methods.

[0043] In this example, by determining the radius r by approaching one side of the mobile robot, and using the radius r1 formed by the mobile robot, plus a safety distance j, the mobile robot can be as close to the rear end of the obstacle as possible while avoiding collision between the mobile robot and the obstacle. Within time T, the laser radar can better determine whether the obstacle has moved away, thereby improving the accuracy of the judgment.

Claims

1. A method for avoiding obstacles for a mobile robot, characterized in that: The specific steps include: S1 uses the mobile robot's lidar to obtain surrounding environment information and form a grid map, and uses the A* algorithm to plan the original path of the mobile robot; S2 The mobile robot continuously detects whether there are any obstacles on the original path while walking along the original path. If an obstacle is detected, a temporary safe stopping point Q is determined between the mobile robot and the obstacle. The method for determining the temporary safe stopping point Q is: S21 calculates the coordinates of the virtual center point O of the obstacle based on the obstacle coordinate information scanned by the laser radar (x k ,y k ); The virtual center point of the obstacle (x k ,y k ) is the average value of the obstacle coordinates obtained by scanning; S22: Set the edge of the front edge of the mobile robot that is perpendicular to the original path of the current mobile robot position as edge e, and determine a center line s that passes through the virtual center point O of the obstacle and is parallel to edge e; S23 uses the laser radar to scan the obstacle edge f on the side of the mobile robot with the center line s as the boundary, and obtains the coordinate point (x z ,y z ); S24 According to (x k ,y k ) and (x z ,y z ) Calculate the radius r of the virtual obstacle circle with the virtual center point of the obstacle as the center; S25 Determine the temporary safe stopping point Q at a distance L from the virtual center point O of the obstacle on the original path, where L = r + r1 + j, where r1 is the maximum radius of the mobile robot, and j is the safe distance between the virtual circle of the obstacle formed by r and the virtual circle of the mobile robot formed by r1; S3 The mobile robot stays at the temporary safety stop Q for time T and continues to detect obstacles through the lidar. If obstacles are detected within time T, an obstacle avoidance path is planned. The obstacle avoidance path allows the mobile robot to avoid the obstacle and then follow the original path. If the obstacle is detected to disappear within time T, the mobile robot continues to follow the original path.

2. The obstacle avoidance method for a mobile robot according to claim 1, wherein: In S21, (x i ,y i ) is the obstacle coordinate information, i is the i-th position point on the obstacle, and m is the total number of points in the horizontal and vertical directions of obstacle detection.

3. The obstacle avoidance method for a mobile robot according to claim 1, wherein: In S23, the coordinate point (x k ,y k ) is mapped to the map used by the A* algorithm to plan the original path of the mobile robot, with coordinate points (x k ,y k ) is the center of the circle and passes through the edge f of the obstacle scanned by the laser radar. The edge of the obstacle scanned by the laser radar is the distance from the coordinate point (x k ,y k ) is determined as the point with the largest coordinate (x z ,y z ).

4. The obstacle avoidance method for a mobile robot according to claim 1, wherein: In S24, the radius r of the obstacle virtual circle is calculated as follows: 。 5. The obstacle avoidance method for a mobile robot according to claim 1, wherein: Assume the length of the mobile robot is L, and the width of the mobile robot is W. .

6. The obstacle avoidance method for a mobile robot according to claim 1, wherein: j is pre-set in the mobile robot.

7. The obstacle avoidance method for a mobile robot according to claim 1, wherein: The dwell time T is preset in the mobile robot.

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