Modeling and Realtime Simulation of an Automatic Gearbox using Modelica
Martin Otter, Clemens Schlegel, E. Elmqvist · elib (German Aerospace Center) · 1997
To speed up the development cycle of electronically controlled mechanical devices, hardware-in-the-loop simulation is used more and more. Applying this method to an automatic gearbox of a car, the electronic transmission control hardware is tested against a model of the gearbox, which is simulated in realtime. Modeling such a system is a demanding task, because its structure varies during gearshift. Since the gearbox investigated has six switching elements (clutches and freewheels) the actual structure has to be found amongst 2 6 = 64 possible configurations. It is shown how such a variable structure system can be modeled with Modelica and how a consistent configuration can be found in realtime after a gearshift occured. The results presented show that it is possible to simulate variable structure systems in realtime using standard realtime simulation hardware and appropriate software tools. INTRODUCTION Comfort standards regarding to gearshift of automatic gearboxes of vehicles inc...