Today, OEMs are challenged with an increasing number of powertrain variants and complexity of controls software. They are facing internal pressure to provide mature and refined calibrations earlier in the development process. Until now, it was difficult to respond to these requests as the drivability's calibration tasks are mostly done in vehicles. This paper describes a new methodology designed to answer these challenges by performing automated shift quality calibration prior to the availability of vehicles. This procedure is using a powertrain dynamometer coupled with a real-time vehicle dynamics model.
By using a Power Train Test Bed (PTTB), a physical vehicle is not required. As soon as the vehicle dynamics model and its parameters have been defined, it can be simulated on the PTTB and drivability calibrations can be developed. A complete powertrain is coupled with low inertia and highly dynamic dynamometers. A high fidelity vehicle dynamics model running in real-time simulates the complete vehicle. A Design of Experiments tool performs the maneuvers and modifies the calibration parameters. A drivability assessment tool provides objective scores used as targets for optimization. System response modeling and calibrations optimization is then performed offline creating multiple datasets according to different criteria.
This paper shows that using this methodology, good correlation between a vehicle and the simulated vehicle on the PTTB is achieved. It also demonstrates that the optimum calibration for best drivability is the same between the vehicle and the PTTB. These results confirm that automated calibration for transmission is achievable in a PTTB.