Smart Object-based Agile Production Management For Mixed-model Assembly Line

Confronted with fierce competition and constantly changing of globalizing market, more and more enterprises have been employing agile manufacturing (AM) technology to continually strengthen manufacturing process's agility and improve thus accurate and immediate responding ability to dynamic market requirement. Therefore, manufacturing process's agility is the pursuing goal of manufacturing enterprise and advanced manufacturing (AM) research. Optimizing organization and automatically acquiring real-time state information of production resources (such as people, equipments, materials) are the key to achieve this goal. To meet the agility requirements of production management in discrete manufacturing, RFID (Radio frequency identification) and the thoughts of IOT (the Internet of Things) are employed in the dissertation. The aim is to establish innovative production management and organization mode, in order to break through the development bottleneck of current production management.The dissertation takes mixed-model assembly line (MMAL), which is widely adopted in discrete manufacturing, as research background, production management of MMAL as research object, RFID and the thoughts of IOT are brought into workshop. Smart object of manufacturing system is presented and created. Then smart object-based agile production management model is studied. On this basis, the key technical problems of the model is further studied, such as real-time manufacturing data acquiring and processing, production process control and material feeding optimizing. And a series of research results of smart object-based agile production management are formed. The main content is as follows:â‘ A smart object-based agile production management model for MMAL is studied. Abundant real-time manufacturing information is the key to realize agile production management. The asynchronous of material flow and information flow is the bottleneck of automatically acquiring real-time manufacturing information. Therefore, it is proposed to adopt RFID technology to identify and track workshop production objects, and those objects become smart objects with real-time information feedback and interactive function. Then, taking reference from the thoughts of IOT, a smart object-based ubiquitous manufacturing information feedback and sharing architecture is constructed, and it supports workshop production management with abundant real-time manufacturing information.Then, an agile production management model for MMAL which can satisfy the agility requirements for manufacturing process is presented, and its frame, network support system and integration operation mode are established. On one hand, the model can realize the seamless integration of information system, manufacturing environment and people with the support of smart object technology. On the other hand, it supports transparent cooperative manufacture of different workshops of enterprises in virtual enterprise, or between clients and enterprises. So, the agility of responding to manufacturing event can be improved.â‘¡Reliable data is essential for realizing agile production management. To process RFID unreliable data that is caused by wireless communication or complex manufacturing environment, RFID real-time data processing technology in manufacturing environment is researched. Firstly, RFID data flow is transformed into event to process data conveniently, and a RFID event model is established, including RFID basic events and complex events. Then, RFID application reliability in complex manufacturing environment is analyzed and summarized, and a set of indexes for evaluating RFID application reliability are suggested. The technique system of improving RFID application reliability from improving equipment, optimizing RFID deployment scheme and processing data is put forward. Finally, from the aspect of RFID data process and optimization, a layered data processing model is set up to improve RFID application reliability. By cleaning and correcting unreliable data, the model can provide reliable real-time data for back-end agile production management application. The successful application of the model in a manufacturing system proves its feasibility.â‘¢Ineffective production process control of MMAL is the bottleneck of agile production management. Therefore, on the basis of transparent workshop which is constructed by smart object technology, new production process controlling technology of MMAL is studied. Firstly, the product assembly process of MMAL is formally described. Then, a new assembly process visualized method, which is management layer-oriented and smart object-based, is presented to realize transparent monitoring to production process, and agility of responses to production event is improved. Moreover, to solve the problem of ineffective product quality control of manual assembly, with the support of smart object technology and procedure-level digital production task, a new workstation-oriented assembly process quality control method is proposed to strengthen accurate control of production process and improve product quality.â‘£Effective material feeding is the core of realizing agile production management. Traditionally material feeding method, which lacks of real-time production information, is hard to agilely respond to frequent state and plan change in MMAL. To solve the problem, on the basis of the synchronization of material flow and information flow which is realized by smart object technology, a new agile material push and pull feeding model (AMP2FM) is put forward, which integrates real-time production progress information. Following the principle of positive service, the smart object automatically orders material supply center to deliver necessary material to assembly line. The problems of wrong or miss feeding, lack of material and material accumulation, etc. are solved. Moreover, to satisfy the BOM digitalized requirement of workstation material delivery, a workstation-centered material feeding BOM construction method is proposed.The study mentioned above and the designed corresponding agile production management system has been successfully applied to a manufacturing enterprise's motorcycle MMAL. It has contributed a lot to improve manufacturing process agility, enhance manufacturing process stability and improve enterprise's response ability, and the dissertation's research result is testified.