# A Study on Design and Control of the Multi-Station Multi-Container Transportation System
## 1 Introduction
According to [5], the Vietnamese mechanical industry has been exposed to several limitations, such as backward technologies, lack of domestic raw materials, insufficient quality of human resources and weak management effectiveness, difficulties in mobilizing capital, and developing markets and competition. After considering the above issues, the design of an ATS based on serial and parallel hung conveyors is selected, as this is the fundamental system in the mechanical industry and is completely achievable. The ATS introduced in this article consists of three different mechanical modules, which are named the forward motion module, the line switching module, and the lifting module. These modules will be operated as independent and controllable mechanical units. With the proposed multi-station ATS, the control system will need to address the complexity of distributing multiple containers to various stations. In addition, the solution for products distribution at the switching points where multiple containers appear at nearly the identical time also needs to be taken into account. For individual container identification, [PERSON] et al., in [6], applied the radio frequency identification (RFID) technology associated with the conveying system. [PERSON] et al., in [7], proposed an arrangement of RFID readers along the conveying lines to determine the crucial location in a complex system, while [PERSON] et al. also proposed a system using RFID technology to identify products with the RFID tags being attached on their surface [8]. According to [PERSON] et al., in [9], RFID systems are presently rapidly developing. The authors in [9] also stated that the radio frequency of 13.56 MHz is used in the access control system and payment systems, as well as for identifying goods in warehouse systems and books in library systems. Based on the previous ideas, the RFID system is selected for the identification of moving containers in the system. In general, the ATS control system proposed in this paper is designed using RFID technology which can identify and locate the containers. For data processing and data management, the server with a database is managed to deal with the logical transportation problem. The actuator system actuators, which are electrical motors, are controlled by a PLC and other expansion modules. In addition, the system needs to be designed to operate stably, even after a power failure, so a database will be managed to store and update information continuously. With the database, the control system will always be able to access the immediate operating status, as well as which stations the containers are heading to. The author's contribution is to integrate the active line switching feature into the traditional conveyor system with an appropriate control system and logic algorithm. Therefore, the products can be automatically redirected to other stations, without depending on a passive guidance mechanism or manual method. This ATS, which employs the overhead conveyors, has corrected the mentioned problem in a more feasible and achievable approach, considering the domestic technology and logistics situation. This system adopts RFID technology to identify containers. RFID is also a technology that has been widely applied in many fields to develop in identification and management. Therefore, we can localize the manufacturing process without depending on the sophisticated foreign system with excessive cost. The novelty of this study is to present a creative solution to the problem of automated freight. This solution includes a mechanical system including overhead conveyors integrated with active line switching mechanisms to change lines leading to various stations. Along with the design of this ATS, the controller, the signal processing block, the information management block, and the logic algorithm for route planning and distributing the containers are presented in detail.