# Simulation on Cooperative Changeover of Production Team Using Hybrid Modeling Method
## 1 Introduction  
With the increasingly fierce market competition and the diversified demand of customers, the traditional large-scale lot production mode of manufacturing industry has been gradually replaced by production modes such as multi-variety and small-quantity. The decrease of production batches leads to frequent changeover operations during the production process, which affects the overall performance of the production system.  
As an important link in the production process, changeover refers to the process of converting machines in a production line from producing one kind of product to another, involving complex knowledge processing operations such as programming, debugging and inspection. Reference [1] suggests that the changeover time has significant impacts on productivity, lead time, work-in-process inventory and quality. Therefore, it is necessary to improve the level of quick changeover.  
Because the changeover process involves a lot of complicated manual work, it cannot be completely replaced by artificial intelligence and automation equipment; it still needs to rely on a high-quality production team. In addition, the changeover task is easy to decompose and suitable for operators to complete through cooperation, so the changeover operation requires a high degree of human-machine collaboration and human-human collaboration. On account of the cost of skill training, the skills possessed by operators are usually complementary [2], and the cooperative changeover method is oftenused as a way to shorten the changeover time and balance the workload. However, frequent cooperative line-changing would affect the work of too many workers. Therefore, cooperative changeover could not improve the performance of production systems in all scenarios. Additionally, the effectiveness of cooperative changeover depends on the production scenario and the degree of cooperation. For example, with the same cooperative changeover mode, the effect in a production scenario where new products are introduced frequently will certainly differ from the effect in a production scenario where mature products are mass-produced. Starting from this problem, this paper divides cooperative changeover into four modes according to the degree of cooperation: non-cooperation, cooperation for mature products, cooperation for new products and total cooperation. The effects of different cooperative changeover modes on the production system are then studied in various production scenarios. The purpose of this research is to offer managers some quantitative suggestions, so that they can decide which cooperative changeover mode should be adopted in a certain production scenario.  
In addition, the method used to conduct research is another important problem. Given that the production process contains a large number of stochastic, discrete events and nonlinear relationships, and operators are active and collaborative, simulation is considered to be the most effective research method. To describe the operators with autonomy and cooperativity in the production system, it is suitable to use the Agent-Based Simulation (ABS) method [3]. The production team can be constructed into a multi-agent system by the ABS method, describing the cooperative changeover behavior of operators [4]. On the other hand, the whole production process has the characteristics of discrete-event system [5], therefore a single ABS modeling method is not suitable for describing the entire production process. Considering these two factors, this paper proposes a hybrid modeling method consisting of multi-agent systems and discrete events.  
To sum up, this study is done for the purpose of solving two problems: (1) how to construct a hybrid simulation model of a production system to support the simulation study of different cooperative changeover strategies in various scenarios and (2) in a certain production scenario, what kind of cooperative changeover mode is more suitable.