| In the warehousing industry,the application of mobile robots can effectively improve the operating efficiency of the warehouse.The navigation and positioning system plays an important role in the autonomous movement of the robot,and is the precondition for the robot to complete various tasks in warehouse.The traditional positioning method has the disadvantages of poor positioning accuracy,cumulative error,slow response speed and the need to store a large amount of environmental information.Compared with traditional positioning methods,landmark positioning has significant advantages such as non-contact,strong flexibility,and speed.AprilTag positioning is a type of landmark positioning.In this study,a monocular camera was used to identify tags of different shapes and sizes,the positioning of the robot can be realized.AprilTag positioning combines a fast detection algorithm with an encoding system,which can improve the robustness of the system and reduce the effects of occlusion and lens distortion.In this paper,based on AprilTag,the robot's motion control,perceptual positioning and path planning algorithms were designed to realize the autonomous movement of mobile robots in the warehouse.The main work is as follows:(1)The main structure of the mobile robot and the sensor installation location were designed according to the warehouse layout.Based on the ROS framework,the overall control plan of the mobile robot navigation and positioning system was formulated.The hardware selection of the mobile robot platform was completed,and the mobile robot platform also was built.The motion control system of the robot was modeled and simulated.Based on the simulation results,the algorithm for motion control and executing instructions was also designed in this study.(2)The QT interface program was designed to realize the establishment and storage of warehouse maps.Based on the preset position and recognition result of the AprilTag,the positioning algorithm was designed,and the positioning of the robot in the warehouse was realized.The path planning algorithm was designed to solve the shortest path that the robot walks in the warehouse,and accurate action instructions were generated according to the path information.Aiming at unknown obstacles in the warehouse,obstacle avoidance algorithms were designed.(3)In Gazebo,the warehouse model was built and the tags were laid out.According to the connection relationship of each part of the mobile robot,a three-dimensional model of the robot was established.The differential drive plug-in was used to control the robot movement in the simulation environment.The camera plug-in and the lidar plug-in were used to realize the perceptual positioning and obstacle avoidance of the simulated robot.Through simulation,the feasibility of the navigation and positioning system algorithm was verified.On the built robot platform,the autonomous mobile experiment was completed,and the feasibility of the system in the real environment was verified.Experimental and simulation results show that the navigation and positioning system based on AprilTag can realize autonomous movement of mobile robots in warehouses;the designed obstacle avoidance algorithm can enable mobile robots to avoid known and unknown obstacles. |
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