Research On Modeling And Steering Technoloy Of Discrete Manufacturing Workshop

Development of Information Technology has been promoting the changes of Production Mode. More and more small and medium discrete manufacturing enterprises want to achieve the goals of improving the production efficiency, reducing the production costs and improving the products’quality by means of the workshop-production-field management with Information Technology. However, many enterprises encountered lots of problems as the Information Technology introduced into the workshop-production-field management thoroughly. To build a remote lean cockpit is the goal of this paper. The controller, without having to visit the workshop-production-field, can get the workshop production state and control the operation of the production process remotely with the lean cockpit.There are three key technologies, which include the modeling of the workshop production state, the analysis of the deviation of the production state and the dynamic production scheduling of the workshop-production-field, to be solved to build the remote lean cockpit. The three key technologies are the problems faced by the production management with Information Technology.The model of the workshop production state is the basis to research on the other key technologies. The fundamental elements of the workshop-production-field include the workpiece and the workstation. The relation between the workpiece and the workstation was built through the working procedure. Information node was the abstraction of the combination of the workpiece, the working procedure and the workstation. The relation between the information nodes has been represented, and the attributes and operations of the information node have been set forth. The workshop production state has defined on the basis of information node as a fundamental unit. The relation named RSD between the production data of the workshop and the state of the workpiece, the working procedure and the workstation has been represented. The relation named RSI between the state of the information node and the state of the workpiece, the working procedure and the workstation has also been set forth. Thus the relation between the production data and the state of the information has been established. The model of the workshop-production-state has been built accordingly. The model of the workshop-production-state is simplified by adopting the model of the information node.The ideal production state of the workshop-production-field is determined by benchmark production process, and the benchmark production process is formulated by production scheduling. The actual production process runs according to the activation sequence of information nodes which is determined by the benchmark production process. That the actual production process is consistent with the benchmark production process is the controller’s expectation. However, the actual production process deviates from the benchmark production process frequently as there are lots of random factors in the workshop-production-field, and the deviation symboled e(t) between actual production state and ideal production state comes into being. It can be compared one variance with the other only they are homogeneous, so the deviation e(t) was subdivided into the deviation of production time and the deviation of production cost etc. The calculation methods of the deviation e(t) was represented. By introducing the concept of the correlative module of information nodes, the mechanism that the deviation e(t) influences the production process was represented. That mechanism is the basis of expounding prediction deviation.It needs to reschedule frequently to meet the demand of actual production with the changes in the actual production process. To improve the production efficiency of the enterprises, to reduce the production costs and to improve the products’quality are the goals of the dynamic production scheduling. That is the multi-objective optimization problem. The concept of equivalent costs was put forward to convert the multi-objective optimization problem into single-objective optimization problem. On the basis of elaborating the relation among the time, the costs and the quality, they are converted into equivalent costs. It is the objective function of the scheduling problem that minimizes the equivalent costs. And the constraints of the scheduling problem are that the deviations of the production state do not exceed the threshold quantity. Several typical situations that trigger dynamic production scheduling have been represented according to the workshop production state. In connection with the characteristics of these situations, the suitable scheduling policy and scheduling algorithm were put forward to achieve the scheduling objective which minimizes the equivalent costs. The scheduling algorithm must be efficient to meet the real-time nature of the dynamic production scheduling. The scheduling algorithm of phased optimization based on information node was put forward, with the efficient nature by combining heuristic rules and neighborhood-search algorithm that takes the optimal solution in the time neighborhood as the heuristic search direction.On the basis of the research above, the architecture of the remote lean cockpit was built, and the theory and methods represented in this paper are verified to be feasible with a experimental case.