Mapping method, computer-readable storage medium, and robot

Patent metadata

Field	Value
Publication number	US-12535822-B2
Application number	US-202318143596-A
Country	US
Kind code	B2
Filing date	May 4, 2023
Priority date	Nov 6, 2020
Publication date	Jan 27, 2026
Grant date	Jan 27, 2026

Abstract

A mapping method, a computer-readable storage medium, and a robot are provided. The method is applied to a robot including a first lidar and a second lidar, where the first lidar is installed at a position higher than that of the second lidar. The method includes: obtaining a first laser key frame; calculating a current pose of a robot based on the first laser key frame; updating a first probability map based on the current pose and the first laser key frame; obtaining a second laser key frame; updating a second probability map based on the current pose and the second laser key frame; and generating a fused grid map for navigating the robot based on the updated first probability map and the updated second probability map, thereby greatly improving the stability of positioning and navigation.

First claim

What is claimed is:

1 . A computer-implemented mapping method for a robot having a first lidar and a second lidar, wherein the method comprises:
providing the robot comprising a processor electrically coupled to the first lidar and the second lidar, wherein the first lidar is installed at a first position on the robot, the second lidar is installed at a second position on the robot, and the first position is higher than the second position, and wherein the first position prevents the first lidar from detecting a movable object in an external environment where the robot is located, and the second position enables the second lidar to detect the movable object; collecting, by the first lidar, a current laser key frame to take as a first laser key frame; calculating, by the processor, a current pose of the robot based on the first laser key frame; updating, by the processor, a first probability map based on the current pose and the first laser key frame, wherein the first probability map is a probability map corresponding to the first lidar; collecting, by the second lidar, a current laser key frame to take as a second laser key frame; updating, by the processor, a second probability map based on the current pose and the second laser key frame, wherein the second probability map is a probability map corresponding to the second lidar; generating, by the processor, a first grid map corresponding to the updated first probability map; generating, by the processor, a second grid map corresponding to the updated second probability map; and obtaining, by the processor, a fused grid map based on the first grid map and the second grid map, and navigating the robot based on the fused grid map;
wherein obtaining, by the processor, the fused grid map based on the first grid map and the second grid map comprises:
aligning, by the processor, the first grid map and the second grid map according to a preset relative pose conversion relationship between the first lidar and the second lidar;
determining a grid in the fused grid map as a black grid, in response to the grid meeting a first preset condition that the grid corresponds to a black grid in the first grid map;
determining the grid in the fused grid map as a white grid, in response to the grid meeting a second preset condition that the grid corresponds to a grid that is not a black grid in the first grid map but corresponds to a white grid in the second grid map; and
determining the grid in the fused grid map as a gray grid, in response to the grid neither meeting the first preset condition nor meeting the second preset condition.

2 . The method of claim 1 , wherein generating the first grid map corresponding to the updated first probability map comprises:
determining an occupancy probability of a target grid in the updated first probability map, wherein the target grid is any grid in the first grid map; and determining a grid type of the target grid according to the occupancy probability.

3 . The method of claim 2 , wherein determining the grid type of the target grid according to the occupancy probability comprises:
determining the target grid as a black grid, in response to the occupancy probability being larger than or equal to a preset probability threshold; determining the target grid as a white grid, in response to the occupancy probability being smaller than the preset probability threshold; and determining the target grid as a gray grid, in response to the occupancy probability being null.

4 . The method of claim 1 , wherein the relative pose conversion relationship is determined by:
obtaining a first ranging result of the first lidar for a target object and a second ranging result of the second lidar for the target object, wherein the target object is placed vertically; and determining the relative pose conversion relationship based on the first ranging result and the second ranging result.

5 . The method of claim 4 , wherein a difference between the first ranging result and the second ranging result is calculated to obtain a horizontal distance between the first lidar and the second lidar, and the horizontal distance is taken as the relative pose conversion relationship.

6 . The method of claim 1 , wherein updating a first probability map according to the current pose and the first laser key frame comprises:
updating a first count value and a second count value of each raytrace grid in the first probability map corresponding to the first laser key frame according to the current pose, wherein the raytrace grid is a grid of the first probability map where a ray from the first lidar to the obstacle passes, the first count value is an amount of times the grid being hit by the ray emitted from the first lidar, and the second count value is an amount of times the grid is the raytrace grid; and obtaining the updated first probability map by updating an occupancy probability of each link grid in the first probability map based on the updated first count value and the update second count value.

7 . The method of claim 6 , wherein the occupancy probability of each raytrace grid in the first probability map may be calculated using an equation of:
P (hit1)= n 1/visit1; where, n1 denotes the first count value, visit1 denotes the second count value, and P(hit1) is the occupancy probability of the raytrace grid in the first probability map.

8 . The method of claim 1 , wherein calculating, by the processor, the current pose of the robot based on the first laser key frame comprises:
performing, by the processor, iterative optimization by Gauss-Newton matching method so that laser contour points contained in the first laser key frame are aligned with contour points of the first probability map, and obtaining the aligned laser contour points; and back-calculating the current pose of the robot according to the aligned laser contour points.

9 . The method of claim 8 , wherein the first probability map is a probability map created according to each laser key frame collected by the first lidar; and
wherein the first probability map is created when the first lidar captures the first laser key frame, and is updated whenever a laser key frame is collected by the first lidar.

10 . A non-transitory computer-readable storage medium for storing one or more computer programs, wherein the one or more computer programs comprise:
instructions for collecting, by a first lidar of a robot, a current laser key frame to take as a first laser key frame; instructions for calculating a current pose of the robot based on the first laser key frame; instructions for updating a first probability map based on the current pose and the first laser key frame, wherein the first probability map is a probability map corresponding to the first lidar; instructions for collecting, by a second lidar of the robot, a current laser key frame to take as a second laser key frame, wherein the first lidar is installed at a first position on the robot, the second lidar is installed at a second position on the robot, and the first position is higher than the second position, and wherein the first position prevents the first lidar from detecting a movable object in an external environment where the robot is located, and the second position enables the second lidar to detect the movable object; instructions for updating a second probability map based on the current pose and the second laser key frame, wherein the second probability map is a probability map corresponding to the second lidar; instructions for generating a first grid map corresponding to the updated first probability map; instructions for generating a second grid map corresponding to the updated second prob

Assignees

• Ubtech Robotics Corp Ltd

Inventors

• Zhang Simin
• Liu Zhichao

Classifications

• G05D1/024

  in combination with a laser (lasers per se H01S) · CPC title

• G05D1/0214

  in accordance with safety or protection criteria, e.g. avoiding hazardous areas (monitoring the location of vehicles within a certain area, e.g. forbidden or allowed areas, in traffic control systems for road vehicles G08G1/13) · CPC title

• G05D1/0274 Primary

  using mapping information stored in a memory device (navigation using map-matching G01C21/30) · CPC title

• G05D1/246

  using environment maps, e.g. simultaneous localisation and mapping [SLAM] · CPC title

• G01S17/931

  of land vehicles · CPC title