# Development and Verification of a Simulation Model of an Automated Assembly Line
## 4 Developing the Automated Assembly Line Model  
The design of the simulation model in Tecnomatix Plant Simulation began with the creation of a 2D model. Basic objects like EventController, Source and Drain have been inserted. Assembly stations (ST_1, ST_2, ST_3, ST_4, ST_5, ST_6) were mapped using the Station object and connected using the Conveyor object, which is responsible for the movement of products along the line. All objects have been connected to each other by Connector. In order to simplify the simulation model of the assembly line, the mapping of the vision system and the station with the cooperating robot was omitted. The predesigned appearance of the line is shown in Figure 4.  
Figure 3: Arrangement and numbering of assembly stations. Figure 2: Transport pallet (**A**) and example of the product (**B**). In the next step, it was decided to reflect the time in which the product travels a given section of the conveyor. This is an important step from the point of view of correct model development. To remain clear, the simulation model does not represent the actual dimensions of the assembly line. The actual dimensions would make the model much smaller. Therefore, it was not possible to enter the speed of movement of the product, so the focus was on reflecting time. For this purpose, measurements of the time of the product's passage through a given section of the real conveyor were made and then entered into the Conveyor edit window in the Time cell of each section of the simulation model. The program assigned the appropriate speed of movement of the product for the given time. Then, the number of products that can move on the line at the same time was adjusted. Six objects have been defined in the simulation model, which simulates products transported on pallets. The next stage (one of the most difficult) was to develop a way to make it possible to arrange the order of the product's passage through the stations and determine the time of the assembly operation. The first step was to develop the MyWorkPlan table, in which it is defined which stations a specific product is to pass through and the assembly time. For this purpose, a DataTable object was inserted and the name was changed to MyWorkPlan (Figure 5), where parts (Part) are defined in the first column, and in the second column, by selecting individual Operations for MyPart A-F cells, you can go to the window where the plan and time are set (Figure 6). The first column, Operation for MyPart, defines the stations in the order in which the product is to pass through them. The Setup time column contains the times that are needed in the real model of the assembly line to define the pallet and read the given travel scenario. For ST_1, the time is 3.90 s, for the remaining stations 2.30 s. In the last column, Processing time, you can enter the time needed to perform the assembly operation at the station. A script was then developed for stations to fetch times from MyWorkPlan. The Method object was used for this, thanks to which you can save scripts. The method was called ProcessingTimeInFormula (Figure 7). Workstations, in order to download data from MyWorkPlan, must call the method developed above, which is why a method was assigned to each workstation. Figure 4: Initial design of the assembly line. In the next step, a method was developed which was called MyExitControl (Figure 8). Thanks to it, the correct passage of products through the line is possible. The method refers to MyWorkPlan, from where the positions are read. The product enters the line through the source and then passes through the stations in a predetermined order. Figure 5: MyWorkPlan. Figure 6: A view for defining a travel plan and times after selecting a cell “Operations for MyPart...”. Figure 7: ProcessingTimeInFormula view. The EventController displays the duration of the entire simulation. In a simulation model, you need to track the simulation time of a single product.