In this paper a systematic approach is presented for model simplification. The approach is applied for simplifying a detailed dynamic hybrid model of an electro-pneumatic clutch system that was originally developed from first engineering principles. The model simplification is performed by applying simplifying assumptions to the model. The top-down way of traversing the model elements using their hierarchy tree ensures the systematic way of the simplification. With this systematic approach the resulted simplified models preserve the physical meaning of the variables and parameters, while they complexity are decreased significantly.
Dynamic system models constructed for dynamic simulation, with high accuracy, are sometimes too detailed and complex for other applications e.g. for model based control design. Moreover the integration of complex models into another ones further increases the ...view middle of the document...
Unfortunately, these methods are purely black-box in nature because the physical meaning of the state variables and parameters in the reduced model is completely lost.
As opposed to the above methods the model structure simplification techniques, reported in  offer a grey-box alternative to model reduction for lumped dynamic models using the hierarchical structure of the model elements. A top-down way of traversing the model elements using their hierarchy tree offers a systematic way of doing model reduction, which can be done more efficiently instead of using heuristics .
The above method is applied in  to obtain a simplified model of a single protection valve in an electronic brake system, where the model elements to be left out are selected based on simulation experiment and engineering insight.
In this paper this systematic model simplification procedure is applied to a dynamic hybrid model of an electro-pneumatic clutch system to derive simplified models for faster simulation and for control design purposes.
In a vehicle driveline, when gear change is demanded, the connection between the engine and the gearbox must be disengaged before any gear shifting procedure is started. This process along with the reconnection of the engine and the gearbox is done by the clutch. The connection is disengaged in the connection point of the engine shaft and the gearbox input shaft, where normally the clutch transmits the momentum through the clutch disc. The clutch friction disc, the pressure plate and the flywheel are rotating together due to the friction force between them. This force is caused by the normal force of a disc spring, which pushes the clutch pressure plate to the friction disc and the flywheel. When the clutching is demanded, Solenoid Magnet Valves (abbreviated as SMV throughout the paper) driven electro-pneumatic actuator pre-stress the disc spring, which lets the clutch pressure plate to move apart from the friction disc, thus terminates the connection. The general layout of the electro-pneumatic clutch (EPC) system  with its close surrounding can be seen in Fig. 1.