| dc.description.abstract | This thesis aims to design an automatic mail sorting system for bill-type letters. This system allows users to place multiple letters into a mail dispensing device, which then sequentially dispatches them to a mail platform. Through image processing, the system recognizes each letter′s postal code. It utilizes a 6-DoF robotic arm to transform the letters into corresponding mail-sorting cabinets.
The research objectives of this thesis are as follows: In hardware, designing structure diagrams and manufacture them by a laser cutting machine, the following three issues have been achieved: (1) Mail dispensing device capable of sequentially sending envelope and storing multiple letters, (2) Mail platform for recognition, and (3) Mail sorting cabinet. In the postal code recognition algorithm section, utilizing two web cameras above and below the mail platform, the following six topics were achieved: (1) Identify the front/back side of the bill-type envelope, (2)Recognize and correct the tilt angle of the envelope, (3) Locate and crop the postal information box, (4) Classifying Chinese and numeric characters, (5) Use deep learning network to recognize digits, and (6) Extract the postal code algorithm. Additionally, in the motion control of the robotic arm, the following techniques were completed: (1) Establish a virtual environment, (2) Compute the transformation matrix of the robotic arm operation model, (3) Obtain the coordinates of each point from picking up the mail to storing it in the mail sorting cabinet by inverse kinematic control of the robotic arm, and (4) Optimize the inverse kinematic path-planning. Combining the above conditions allows the system to accomplish postal code recognition and mail sorting by the robotic arm.
This study develops a software system using the Robot Operating System (ROS) in the Linux environment. It utilizes TCP/IP for information transmission, enabling real-time data exchange among multiple devices to achieve the design of software-hardware integration and collaboration. In practical experiments, the postal code recognition algorithm performed a correct recognition rate of 95.24%, and the overall sorting accuracy of the system was 94.49%. The experimental results demonstrate that this thesis has successfully established a stable and robust automatic sorting system for bill-type letters. | en_US |