| In recent years,the scale of online shopping users in China continues to grow,and the number of small-scale e-commerce logistics orders also increases.The traditional warehousing logistics operation mode has been difficult to handle such a large number of orders.The mobile manipulator combines the advantages of the flexibility of the mobile platform and the operability of the manipulator,which can sort goods and transport them to the designated place,In this paper,for the process of "goods to people"in warehousing and logistics operations,it is of great significance for the development of modern logistics key technology to carry out the research of mobile manipulator grasping operation.The work of this paper mainly includes the following aspects(1)According to the task requirements of the mobile manipulator,the overall design of the mobile manipulator system is carried out.According to the requirements of mobile manipulator grasping task,the framework of mobile manipulator control system is built,and its main hardware modules are selected.The software system of mobile manipulator is designed,and the upper computer app based on Android is designed and written.(2)Research on positioning and navigation method based on QR code.Aiming at the working environment of logistics warehouse,a positioning and navigation method based on two-dimensional code is designed.Firstly,the grid environment map is constructed,and the path planning is carried out through a*algorithm.Then,according to the two-dimensional code set on the ground,the accurate positioning of mobile manipulator is realized.In the course of dead reckoning,when the two-dimensional code is scanned,the accumulated error of the odometer is corrected to realize the precise positioning of the mobile manipulator.Finally,the positioning experiment of the mobile manipulator is carried out,and the experimental results show that the positioning accuracy meets the design requirements.(3)Kinematics analysis of manipulator.The D-H model of Aubo i5 manipulator is established,the kinematics equation of the manipulator is solved,and the correctness of the kinematics equation is verified in MATLAB.According to the kinematics equation of the manipulator,the end-to-point motion experiment of the manipulator is completed,which makes an important preparation for the motion planning of the manipulator.(4)Research on object recognition and positioning and manipulator motion planning based on ROS(robot operating system).According to the feature that the surface feature of the object to be grasped is not obvious,the object detection and positioning method is designed.The apriltag visual tag is set on the surface of the object to be grasped,and the real-time image obtained by the end camera of the manipulator is processed and decoded to obtain the ID information and pose information of the visual tag,so as to realize the detection and positioning of the object.According to the real working environment of logistics warehouse,a three-dimensional model of mobile manipulator working scene is established in ROS,and RRT(random exploring random trees),RRT*and RRT are compared and analyzed_In order to improve the motion planning performance of connect algorithm in logistics warehouse environment,RRT is selected Connect algorithm as a motion planning algorithm,combined with RRT Connect algorithm and three-dimensional model of working scene make the mobile manipulator avoid the obstacles in the environment and improve the safety of the equipment.(5)Experimental research on the grabbing operation of mobile manipulator.The hardware platform of mobile manipulator is built,and the software node of control system based on ROS is written.Aiming at the problem of large error in traditional visual hand eye calibration,a hand eye calibration method based on ROS is proposed.The experimental results show that the success rate of the task is more than 95%,which can meet the application needs of warehousing logistics. |
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