Deep neural networks based order completion time prediction by using real-time job shop RFID data

In the traditional order completion time (OCT) prediction methods, some mutable and ideal production data (e.g., the arrival time of work in process (WIP), the planned processing time of all operations, and the expected waiting time per operation) are often used. Thus, the prediction time always deviates from the actual completion time dramatically even though the dynamicity of the production capacity and the real-time load conditions of job shop are considered in the OCT prediction method. On account of this, a new prediction method of OCT using the composition of order and real-time job shop RFID data is proposed in this article. It applies accurate RFID data to depict the real-time load conditions of job shop, and attempts to mine the mapping relationship between RFID data and OCT from historical data. Firstly, RFID devices capture the types and waiting list information of all WIPs which are in the in-stocks and out-stocks of machining workstations, and the real-time processing progress of all WIPs which are under machining at machining workstations. Secondly, a description model of real-time job shop load conditions is put forward by using the RFID data. Next, the mapping model based on the composition of order and real-time RFID data is established. Finally, deep belief network, which is one of the major technologies of deep neural networks, is applied to mine the mapping relationship. To illustrate the advantages of the proposed method, a numerical experiment compared with back-propagation (BP) network based prediction method, multi-hidden-layers BP network based prediction method and the principal components analysis and BP network based prediction method is conducted at last.