Flatness-Based Control and Online Trajectory Generation for Electrical Actuators in Combustion Engines

Several different electrical actuators are utilized to influence mass flows in the gas exchange system of modern combustion engines. Control loops for exhaust gas recirculation rate or boost-pressure strongly rely on underlying actuator position control with a high predefined performance level. Position controller design in the industrial practice often builds upon grown, inexplicit controller structures and trial-and-error parametrization methods. The approach presented in this paper uses flatness-based feedforward control as a strategy for systematic integration of a priori system knowledge into an open-loop controller. A major difficulty in this context is the inevitable online generation of appropriate trajectories without unrealistic consumption of computing time and memory. We present two approaches for the trajectory generation, both of which state a realistic compromise between mathematical accuracy, design freedom and computing resources consumption. It will be shown, that a high tracking performance can be realized due to the suggested feedforward controller with only moderate bandwidth of the additional feedback controller.