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Advanced automatic transmissions are controlled by electronic control units (ECUs) which perform the gear change and furthermore a lot of complex control and diagnostic functions. Hardware-in-the-loop simulation (HIL) is a powerful tool to develop and test the control algorithms implemented in the ECUs. The simulation is based upon mathematical models of the different power train components, adapted to the real-time requirements. In this paper an improved real-time model of an automatic transmission with a Ravigneaux planetary gear train is presented. This transmission contains among other components numerous clutches and brakes. The time-variant states of these nonlinear elements (sliding and static friction) lead to numerical problems with respect to real-time simulation. In the suggested model the transferred torques of the different clutches and brakes are calculated using the methods of multi-variable control.

In the research project “New Exhaust Emission Concept”, supported by the Minister of Research and Technology of the Federal Republic of Germany, the main goal was the minimization of the raw exhaust emission of a gasoline engine by operating the engine in its (HC +NOx)-minimum, as well as the improvement of its fuel economy. With respect to these goals it was necessary to develop new control strategies. To preadjust the appropriate electronic control systems already in the laboratory, a real time simulator was developed, to reproduce the sensor signals of a gasoline engine under steady state, but also under dynamic conditions. The paper gives a survey over the technical specifications of the simulator, the method of mathematical engine modelling, the simulation algorithms and the used hardware solution. Some characteristic results show the performance and the adventages of the use of the simulation system.