paper path modeling case in 20 - SIM

ii iii Summary For the design of embedded systems the development of dynamic models of the controlled physical system becomes increasingly important. These models predict the behavior of the system in an early stage of the design process. It is important to use an efficient method for modeling that gives satisfactory results. In this project, a dynamic model has been made of the paper path in an Océ copier system. The modeling language used is bond graphs. 20-SIM software proved to be an excellent tool for the modeling and simulation of the paper path. The most important component for paper transport is the pinch, which thrusts the sheets forwards using two pressing rollers. The modeling of the energetic coupling between sheet and rollers has been the main part of the investigation. For this coupling two options have been considered. First a direct velocity coupling has been investigated. The sheet then follows the velocity of the rollers exactly, when it is pinched. This approach showed an unsatisfactory behavior in the simulations. First the physical behavior was not described well. Secondly this modeling introduced dynamic causality. This flipping of the causality leads to calculation difficulties, while simulating the model. The second approach of modeling the paper-pinch coupling was based on friction. After having investigated friction effects, a one-port model has been made. This model calculates the friction force as a function of the velocity difference between sheet and rollers. With a satisfying physical behavior of the simplified paper path model, an extendible model has been made. This general model can be easily adapted for constructing a specific paper path model. With this model the transport path of the Océ copier has been modeled. A simple form of control has been implemented to imitate several processes in the real copier. This control was based on the assumption that the pinches function as a velocity source for the sheet. Finally, the model behavior has been visualized with a 3D animation. For future use and extension of the models a guide has been written. The main improvements that still can be made in the model are: implementing the path that allows double-sided printing, adding randomness to several processes and reconsidering the control of the pinches.