# A Study on Design and Control of the Multi-Station Multi-Container Transportation System
## 5 Conclusions and Future Developments  
### Conclusions  
The ATS using overhead conveyors has proved its feasibility when applied to BK-RECME. In summary, this paper describes the design and the operating principle, as well as presents the achievements of the implementation of the proposed ATS. The results obtained from this study have shown that this system is feasible and can solve the transport and distribution problems mentioned in this paper. The experimental results satisfied the assumptions and related constraints, which were analyzed in the Discussions section. After having researched, assembled, and experimented with the system operation, with the examination on the performance of the control block, the management block, and database, we identified several shortcomings, which are as follows:  
1. The system vibrates while operating: During system performance testing, vibration is generated because the conveyors are not linked together, but rather are independent mechanical components. As a result, the conveyors will slightly oscillate in a narrow range, creating vibrations in the whole system. This problem is combated by creating an interlink frame between the conveyors, helping to keep the absolute system in a unified and stable block. 2. The noise was generated because of the gearing between the sprocket and the chain of the plastic chain. These represent typical characteristics of the chain-conveyor during operation, and it will require some more innovations to overcome this phenomenon. As a result, this noise may cause discomfort to people in the operating environment, or is not sufficient to satisfy the criteria when applied to office buildings, hospitals, etc. 3. The data transmission line between devices (server, PLC, and database) could be upgraded: An increase in a number of stations in a system will lead to many more data and system variables. Hypothetically, the more variables that occur, the more complicated and difficult it becomes to communicate data through manual TCP/IP. Consequently, the system could be much trickier to control due to the senior level of complexity, although the cost when using TCP/IP protocol is completely reasonable. Fortunately, the prototype system in this paper consists of only three stations and could be applied with manual TCP/IP protocol with little problem. 4. The system has only experimented in a three-station prototype: As the system was implemented at Bach Khoa Research Center for Manufacturing Engineering (BK-RECME, Ho Chi Minh City University of Technology (HCMUT), Vietnam), it was built on a scale of three stations (according to the model in Figure 3). The next target is to expand the system on a larger scale with n stations (n > 3) to help transport m containers. This system has been researched and designed to solve the problem of transporting goods utilizing the space above the ceiling, with the feature of automated line switching to coordinate products flexibly between stations. Although this system is not advanced when compared to other modern systems in the world, it has effectively solved the problem with a more feasible approach. With this system, the load capacity and productivity are far beyond that of the pneumatic system, and the flexibility is also higher than that of the AGV system. This ATS will also avoid space inadequacies when frequent people are passing by because many buildings are already designed and do not plan appropriate aisles for the AGV. Another important innovation is the control algorithm of the system. The authors have come up with a control algorithm for routing and handling the situation if many containers are moving in opposite directions at the line switching point. The proposed algorithm is one of the key points determining the performance of the system. This algorithm has opened up many development directions for transport using multi-station systems, as the success of the line switching algorithm will set the foundation for expanding the system to more stations, more containers, and more lines.