Launch control optimization of transmissions with automated clutch engagement

Thanks to the physical principle of a hydraulic torque converter, launch in classic automatic transmissions is automatically smooth. In low-cost transmissions with installed friction clutches, however, the engagement of the clutch has to be controlled by the transmission control unit (TCU) which makes the calibration parameters responsible for the launch quality. The growing complexity and diversity of modern powertrains increases the calibration effort dramatically, which is why automation of the calibration process for automatic transmissions becomes increasingly important. Through the automated search for optimal values for the launch parameters, the quality of the launch event and the efficiency of the transmission calibration process can be increased significantly. Therefore, an important aspect of this work is to develop strategies for improving the launch quality as a part of the automated transmission calibration. The concept of numerical optimization has proven to be a promising support tool for the engineer. This requires objectification of the usually subjectively rated launch quality, where the main goal is to achieve a fast and smooth clutch engagement at the same time. Based on these goals, a bi-criterion optimization problem is defined and solved by a multi-objective genetic algorithm. The solution of the problem is not unique but always a set of optimal trade-offs between the two conflicting criteria. Besides, a purely determinism based interpretation of the automated calibration process can only partly meet the requirements of practical application since in reality the properties of technical systems scatter. Therefore, robustness is additionally considered as inherent design goal to generally assure high quality and reliability of launch control.