Two-level Dynamic Scheduling Method For RFID-based Fixed-position Assembly

In order to solve the problem of assembling large complex product, such as the complexity of assembly process, the low level of informatization and the difficulty in workshop scheduling. In this paper, we proposed a RFID-based solution for fixed-position assembly. It can achieve dynamic scheduling process through the initial scheduling and rescheduling implementation to ensure the continuity and stability of workshop assembly. This two-level dynamic workshop scheduling problem with this mode is not only a new problem on the production scheduling field, but also an important research topic in aviation, navigation and generating equipment manufacturing process in our country.The two-level dynamic scheduling model of fixed-position assembly is mainly for large complex product which facing fixed position, limited people and the complex characteristics and multi constraints. Through initial schedule with reasonable plan ensure the decentralized production resources with the production process gradually advancing to the dynamic assembly unit, and start the rescheduling mechanism timely through executing fixed-position assembly executive process and judgment of plan according to the production dynamic data of RFID, so as to achieve the plan, execution and control of dynamic production in the workshop.Firstly, the manufacturing mode of fixed-position assembly is introduced overall. This paper elaborates production characteristics and the whole workshop environment of fixed-position assembly from the workshop production angle different from the traditional. According to the bad real-time information sharing degree and the high production complexity, the assembly operation logic of wireless manufacturing workshop based on RFID is proposed.Secondly, analysis and modeling of the two-level scheduling problem of fixed-position are proposed. Through the analysis of characteristics of fixed-position assembly product with process constraints, using its relation between lateral complex assembly tree process graph (process layer) and longitudinal (process path) structure, and combining with the dual optimization method of lateral optimize process constraints and longitudinal optimization process path, the short time and the critical path scheduling rules are proposed. Then the initial scheduling model is established which is designed for the assembly process, assembly island, assembly personnel and other resources. Thus, in order to solve deviation problem of planning process and the assembly executive process caused by real-time disturbance, it should ensure the disturbance and threshold processing mechanism, and then start the workshop rescheduling model timely through adjusting scheduling process dynamically.Finally, a RFID-based solution for fixed-position assembly is proposed. Namely it introduces the RFID-enabled fixed-position assembly workshop management system. This developed solution is extensible and reconfigurable due to several aspects. This model comprises three typical production processes as planning, execution and logistics with the classic JSP problems, which reflects the typical requirements that a manufacturing workshop has for RFID systems. Therefore, the combination of the processes and implementation approaches could ensure a RFID system achieve maximal fitness when it is put into use in a fixed-position workshop.