With help of Matlab/Simulink a model of the monitoring function of the idle speed controller was created. This model was stimulated with data of vehicle measurements and the results were compared with the real vehicle. Nearly the same was done in the Hardware-in-the-Loop simulation. The problem in Hardware-in-the-Loop was not the creation of the model (because here the real engine management unit is used) but to find out all the correct parameters of the vehicle model. To be able to compare the results of simulation and vehicle it is necessary to have identical environmental conditions like the mass of the vehicle, slope of the road but also the current friction losses of the engine.

All three methods were compared. The goal here was a reduction of the very expensive tests with a prototype.