Systematic Model Simplification Procedure Applied to an Electro- Pneumatic Clutch Model

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 their complexity is decreased significantly

H-infinity Backpressure Controller for High Response Engine Exhaust Throttles

Modern engine exhaust restriction valves can be applied not only as retarders. A suitable pressure generation can assist the aftertreatment system (exhaust gas temperature management) and raw emission control as well. To provide these functionalities the exhaust backpressure has to be controlled arbitrarily. In this paper a model-based controller design is demonstrated to minimize calibration effort. A first engineering principle based, mean-value, nonlinear model was described and converted into linear parameter-varying (LPV) form. To satisfy the demands of the above applications the controller needs to be a high dynamic, stabilizing, tracking controller which is robust in the whole relevant engine operation range. The exhaust processes of the individual cylinders generate comparable amplitude pressure oscillations to the expected control accuracy. To fulfill the above requirements and manage the challenge of the exhaust pressure waves an H-infinity controller design method was chosen. In order to handle the saturation of the control signal a high gain anti-windup was applied. Seeking for the lowest possible computational demand the controller order reduction was proposed based on Hankel singular values. Finally the controller performance was demonstrated and evaluated in software-in-the-loop simulations